Apply [timeouts] tg_connect to upstream DC TCP connect attempts

Wire config.timeouts.tg_connect into UpstreamManager; per-attempt timeout uses
the same .max(1) pattern as connect_budget_ms.

Reject timeouts.tg_connect = 0 at config load (consistent with
general.upstream_connect_budget_ms and related checks). Default when the key
is omitted remains default_connect_timeout() via serde.

Fixes telemt/telemt#439

.cargo/deny.toml

@@ -0,0 +1,15 @@
+[bans]
+multiple-versions = "deny"
+wildcards = "allow"
+highlight = "all"
+
+# Explicitly flag the weak cryptography so the agent is forced to justify its existence
+[[bans.skip]]
+name = "md-5"
+version = "*"
+reason = "MUST VERIFY: Only allowed for legacy checksums, never for security."
+
+[[bans.skip]]
+name = "sha1"
+version = "*"
+reason = "MUST VERIFY: Only allowed for backwards compatibility."

.github/codeql/codeql-config.yml

@@ -7,7 +7,16 @@ queries:
   - uses: security-and-quality
   - uses: ./.github/codeql/queries
 
+paths-ignore:
+  - "**/tests/**"
+  - "**/test/**"
+  - "**/*_test.rs"
+  - "**/*/tests.rs"
 query-filters:
+  - exclude:
+      tags:
+        - test
+
   - exclude:
       id:
         - rust/unwrap-on-option

.github/workflows/build.yml

@@ -0,0 +1,39 @@
+name: Build
+
+on:
+  push:
+    branches: [ "*" ]
+  pull_request:
+    branches: [ "*" ]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Install latest stable Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache cargo registry & build artifacts
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-
+
+      - name: Build Release
+        run: cargo build --release --verbose

.github/workflows/release.yml

@@ -5,37 +5,87 @@ on:
     tags:
       - '[0-9]+.[0-9]+.[0-9]+'
   workflow_dispatch:
+    inputs:
+      tag:
+        description: 'Release tag (example: 3.3.15)'
+        required: true
+        type: string
+
+concurrency:
+  group: release-${{ github.ref_name }}-${{ github.event.inputs.tag || 'auto' }}
+  cancel-in-progress: true
 
 permissions:
   contents: read
-  packages: write
 
 env:
   CARGO_TERM_COLOR: always
+  BINARY_NAME: telemt
 
 jobs:
-  build:
-    name: Build ${{ matrix.target }}
+  prepare:
+    name: Prepare
     runs-on: ubuntu-latest
-    permissions:
-      contents: read
+
+    outputs:
+      version: ${{ steps.vars.outputs.version }}
+      prerelease: ${{ steps.vars.outputs.prerelease }}
+
+    steps:
+      - name: Resolve version
+        id: vars
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          if [ "${GITHUB_EVENT_NAME}" = "workflow_dispatch" ]; then
+            VERSION="${{ github.event.inputs.tag }}"
+          else
+            VERSION="${GITHUB_REF#refs/tags/}"
+          fi
+
+          VERSION="${VERSION#refs/tags/}"
+
+          if [ -z "${VERSION}" ]; then
+            echo "Release version is empty" >&2
+            exit 1
+          fi
+
+          if [[ "${VERSION}" == *-* ]]; then
+            PRERELEASE=true
+          else
+            PRERELEASE=false
+          fi
+
+          echo "version=${VERSION}" >> "${GITHUB_OUTPUT}"
+          echo "prerelease=${PRERELEASE}" >> "${GITHUB_OUTPUT}"
+
+  # ==========================
+  # GNU / glibc
+  # ==========================
+  build-gnu:
+    name: GNU ${{ matrix.asset }}
+    runs-on: ubuntu-latest
+    needs: prepare
+
+    container:
+      image: rust:slim-bookworm
 
     strategy:
       fail-fast: false
       matrix:
         include:
           - target: x86_64-unknown-linux-gnu
-            artifact_name: telemt
-            asset_name: telemt-x86_64-linux-gnu
+            asset: telemt-x86_64-linux-gnu
+            cpu: baseline
+
+          - target: x86_64-unknown-linux-gnu
+            asset: telemt-x86_64-v3-linux-gnu
+            cpu: v3
+
           - target: aarch64-unknown-linux-gnu
-            artifact_name: telemt
-            asset_name: telemt-aarch64-linux-gnu
-          - target: x86_64-unknown-linux-musl
-            artifact_name: telemt
-            asset_name: telemt-x86_64-linux-musl
-          - target: aarch64-unknown-linux-musl
-            artifact_name: telemt
-            asset_name: telemt-aarch64-linux-musl
+            asset: telemt-aarch64-linux-gnu
+            cpu: generic
 
     steps:
       - uses: actions/checkout@v4
@@ -43,47 +93,245 @@ jobs:
       - uses: dtolnay/rust-toolchain@v1
         with:
           toolchain: stable
-          targets: ${{ matrix.target }}
+          targets: |
+            x86_64-unknown-linux-gnu
+            aarch64-unknown-linux-gnu
 
-      - name: Install cross-compilation tools
+      - name: Install deps
         run: |
-          sudo apt-get update
-          sudo apt-get install -y gcc-aarch64-linux-gnu
+          apt-get update
+          apt-get install -y \
+            build-essential \
+            clang \
+            lld \
+            pkg-config \
+            gcc-aarch64-linux-gnu \
+            g++-aarch64-linux-gnu
 
       - uses: actions/cache@v4
         with:
           path: |
-            ~/.cargo/registry
-            ~/.cargo/git
+            /usr/local/cargo/registry
+            /usr/local/cargo/git
             target
-          key: ${{ runner.os }}-${{ matrix.target }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          key: gnu-${{ matrix.asset }}-${{ hashFiles('**/Cargo.lock') }}
           restore-keys: |
-            ${{ runner.os }}-${{ matrix.target }}-cargo-
+            gnu-${{ matrix.asset }}-
+            gnu-
 
-      - name: Install cross
-        run: cargo install cross --git https://github.com/cross-rs/cross
-
-      - name: Build Release
-        env:
-          RUSTFLAGS: ${{ contains(matrix.target, 'musl') && '-C target-feature=+crt-static' || '' }}
-        run: cross build --release --target ${{ matrix.target }}
-
-      - name: Package binary
+      - name: Build
+        shell: bash
         run: |
-          cd target/${{ matrix.target }}/release
-          tar -czvf ${{ matrix.asset_name }}.tar.gz ${{ matrix.artifact_name }}
-          sha256sum ${{ matrix.asset_name }}.tar.gz > ${{ matrix.asset_name }}.sha256
+          set -euo pipefail
+
+          if [ "${{ matrix.target }}" = "aarch64-unknown-linux-gnu" ]; then
+            export CC=aarch64-linux-gnu-gcc
+            export CXX=aarch64-linux-gnu-g++
+            export RUSTFLAGS="-C linker=aarch64-linux-gnu-gcc -C lto=fat -C panic=abort"
+          else
+            export CC=clang
+            export CXX=clang++
+
+            if [ "${{ matrix.cpu }}" = "v3" ]; then
+              CPU_FLAGS="-C target-cpu=x86-64-v3"
+            else
+              CPU_FLAGS="-C target-cpu=x86-64"
+            fi
+
+            export RUSTFLAGS="-C linker=clang -C link-arg=-fuse-ld=lld -C lto=fat -C panic=abort ${CPU_FLAGS}"
+          fi
+
+          cargo build --release --target ${{ matrix.target }} -j "$(nproc)"
+
+      - name: Package
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          mkdir -p dist
+          cp "target/${{ matrix.target }}/release/${{ env.BINARY_NAME }}" dist/telemt
+
+          cd dist
+          tar -czf "${{ matrix.asset }}.tar.gz" \
+            --owner=0 --group=0 --numeric-owner \
+            telemt
+
+          sha256sum "${{ matrix.asset }}.tar.gz" > "${{ matrix.asset }}.tar.gz.sha256"
 
       - uses: actions/upload-artifact@v4
         with:
-          name: ${{ matrix.asset_name }}
-          path: |
-            target/${{ matrix.target }}/release/${{ matrix.asset_name }}.tar.gz
-            target/${{ matrix.target }}/release/${{ matrix.asset_name }}.sha256
+          name: ${{ matrix.asset }}
+          path: dist/*
 
-  build-docker-image:
-    needs: build
+  # ==========================
+  # MUSL
+  # ==========================
+  build-musl:
+    name: MUSL ${{ matrix.asset }}
     runs-on: ubuntu-latest
+    needs: prepare
+
+    container:
+      image: rust:slim-bookworm
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - target: x86_64-unknown-linux-musl
+            asset: telemt-x86_64-linux-musl
+            cpu: baseline
+
+          - target: x86_64-unknown-linux-musl
+            asset: telemt-x86_64-v3-linux-musl
+            cpu: v3
+
+          - target: aarch64-unknown-linux-musl
+            asset: telemt-aarch64-linux-musl
+            cpu: generic
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install deps
+        run: |
+          apt-get update
+          apt-get install -y \
+            musl-tools \
+            pkg-config \
+            curl
+
+      - uses: actions/cache@v4
+        if: matrix.target == 'aarch64-unknown-linux-musl'
+        with:
+          path: ~/.musl-aarch64
+          key: musl-toolchain-aarch64-v1
+
+      - name: Install aarch64 musl toolchain
+        if: matrix.target == 'aarch64-unknown-linux-musl'
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          TOOLCHAIN_DIR="$HOME/.musl-aarch64"
+          ARCHIVE="aarch64-linux-musl-cross.tgz"
+          URL="https://github.com/telemt/telemt/releases/download/toolchains/${ARCHIVE}"
+
+          if [ -x "${TOOLCHAIN_DIR}/bin/aarch64-linux-musl-gcc" ]; then
+            echo "MUSL toolchain cached"
+          else
+            curl -fL \
+              --retry 5 \
+              --retry-delay 3 \
+              --connect-timeout 10 \
+              --max-time 120 \
+              -o "${ARCHIVE}" "${URL}"
+
+            mkdir -p "${TOOLCHAIN_DIR}"
+            tar -xzf "${ARCHIVE}" --strip-components=1 -C "${TOOLCHAIN_DIR}"
+          fi
+
+          echo "${TOOLCHAIN_DIR}/bin" >> "${GITHUB_PATH}"
+
+      - name: Add rust target
+        run: rustup target add ${{ matrix.target }}
+
+      - uses: actions/cache@v4
+        with:
+          path: |
+            /usr/local/cargo/registry
+            /usr/local/cargo/git
+            target
+          key: musl-${{ matrix.asset }}-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            musl-${{ matrix.asset }}-
+            musl-
+
+      - name: Build
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          if [ "${{ matrix.target }}" = "aarch64-unknown-linux-musl" ]; then
+            export CC=aarch64-linux-musl-gcc
+            export CC_aarch64_unknown_linux_musl=aarch64-linux-musl-gcc
+            export RUSTFLAGS="-C target-feature=+crt-static -C linker=aarch64-linux-musl-gcc -C lto=fat -C panic=abort"
+          else
+            export CC=musl-gcc
+            export CC_x86_64_unknown_linux_musl=musl-gcc
+
+            if [ "${{ matrix.cpu }}" = "v3" ]; then
+              CPU_FLAGS="-C target-cpu=x86-64-v3"
+            else
+              CPU_FLAGS="-C target-cpu=x86-64"
+            fi
+
+            export RUSTFLAGS="-C target-feature=+crt-static -C lto=fat -C panic=abort ${CPU_FLAGS}"
+          fi
+
+          cargo build --release --target ${{ matrix.target }} -j "$(nproc)"
+
+      - name: Package
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          mkdir -p dist
+          cp "target/${{ matrix.target }}/release/${{ env.BINARY_NAME }}" dist/telemt
+
+          cd dist
+          tar -czf "${{ matrix.asset }}.tar.gz" \
+            --owner=0 --group=0 --numeric-owner \
+            telemt
+
+          sha256sum "${{ matrix.asset }}.tar.gz" > "${{ matrix.asset }}.tar.gz.sha256"
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: ${{ matrix.asset }}
+          path: dist/*
+
+  # ==========================
+  # Release
+  # ==========================
+  release:
+    name: Release
+    runs-on: ubuntu-latest
+    needs: [prepare, build-gnu, build-musl]
+
+    permissions:
+      contents: write
+
+    steps:
+      - uses: actions/download-artifact@v4
+        with:
+          path: artifacts
+
+      - name: Flatten artifacts
+        shell: bash
+        run: |
+          set -euo pipefail
+          mkdir -p dist
+          find artifacts -type f -exec cp {} dist/ \;
+
+      - name: Create GitHub Release
+        uses: softprops/action-gh-release@v2
+        with:
+          tag_name: ${{ needs.prepare.outputs.version }}
+          target_commitish: ${{ github.sha }}
+          files: dist/*
+          generate_release_notes: true
+          prerelease: ${{ needs.prepare.outputs.prerelease == 'true' }}
+          overwrite_files: true
+
+  # ==========================
+  # Docker
+  # ==========================
+  docker:
+    name: Docker
+    runs-on: ubuntu-latest
+    needs: [prepare, release]
+
     permissions:
       contents: read
       packages: write
@@ -92,48 +340,66 @@ jobs:
       - uses: actions/checkout@v4
 
       - uses: docker/setup-qemu-action@v3
+
       - uses: docker/setup-buildx-action@v3
 
-      - name: Login to GHCR
-        uses: docker/login-action@v3
+      - uses: docker/login-action@v3
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
-      - name: Extract version
-        id: vars
-        run: echo "VERSION=${GITHUB_REF#refs/tags/}" >> $GITHUB_OUTPUT
+      - name: Probe release assets
+        shell: bash
+        env:
+          VERSION: ${{ needs.prepare.outputs.version }}
+        run: |
+          set -euo pipefail
 
-      - name: Build and push
+          for asset in \
+            telemt-x86_64-linux-musl.tar.gz \
+            telemt-x86_64-linux-musl.tar.gz.sha256 \
+            telemt-aarch64-linux-musl.tar.gz \
+            telemt-aarch64-linux-musl.tar.gz.sha256
+          do
+            curl -fsIL \
+              --retry 10 \
+              --retry-delay 3 \
+              "https://github.com/${GITHUB_REPOSITORY}/releases/download/${VERSION}/${asset}" \
+              > /dev/null
+          done
+
+      - name: Compute image tags
+        id: meta
+        shell: bash
+        env:
+          VERSION: ${{ needs.prepare.outputs.version }}
+        run: |
+          set -euo pipefail
+
+          IMAGE="$(echo "ghcr.io/${GITHUB_REPOSITORY}" | tr '[:upper:]' '[:lower:]')"
+          TAGS="${IMAGE}:${VERSION}"
+
+          if [[ "${VERSION}" != *-* ]]; then
+            TAGS="${TAGS}"$'\n'"${IMAGE}:latest"
+          fi
+
+          {
+            echo "tags<<EOF"
+            printf '%s\n' "${TAGS}"
+            echo "EOF"
+          } >> "${GITHUB_OUTPUT}"
+
+      - name: Build & Push
         uses: docker/build-push-action@v6
         with:
           context: .
           push: true
-          tags: |
-            ghcr.io/${{ github.repository }}:${{ steps.vars.outputs.VERSION }}
-            ghcr.io/${{ github.repository }}:latest
-
-  release:
-    name: Create Release
-    needs: build
-    runs-on: ubuntu-latest
-    permissions:
-      contents: write
-
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
-
-      - uses: actions/download-artifact@v4
-        with:
-          path: artifacts
-
-      - name: Create Release
-        uses: softprops/action-gh-release@v2
-        with:
-          files: artifacts/**/*
-          generate_release_notes: true
-          draft: false
-          prerelease: ${{ contains(github.ref, '-rc') || contains(github.ref, '-beta') || contains(github.ref, '-alpha') }}
+          pull: true
+          platforms: linux/amd64,linux/arm64
+          tags: ${{ steps.meta.outputs.tags }}
+          build-args: |
+            TELEMT_REPOSITORY=${{ github.repository }}
+            TELEMT_VERSION=${{ needs.prepare.outputs.version }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max

.github/workflows/rust.yml

@@ -1,54 +0,0 @@
-name: Rust
-
-on:
-  push:
-    branches: [ "*" ]
-  pull_request:
-    branches: [ "*" ]
-
-env:
-  CARGO_TERM_COLOR: always
-
-jobs:
-  build:
-    name: Build
-    runs-on: ubuntu-latest
-
-    permissions:
-      contents: read
-      actions: write
-      checks: write
-
-    steps:
-    - name: Checkout repository
-      uses: actions/checkout@v4
-
-    - name: Install latest stable Rust toolchain
-      uses: dtolnay/rust-toolchain@stable
-      with:
-        components: rustfmt, clippy
-
-    - name: Cache cargo registry & build artifacts
-      uses: actions/cache@v4
-      with:
-        path: |
-          ~/.cargo/registry
-          ~/.cargo/git
-          target
-        key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
-        restore-keys: |
-          ${{ runner.os }}-cargo-
-
-    - name: Build Release
-      run: cargo build --release --verbose
-
-    - name: Run tests
-      run: cargo test --verbose
-
-# clippy dont fail on warnings because of active development of telemt 
-# and many warnings
-    - name: Run clippy
-      run: cargo clippy -- --cap-lints warn
-
-    - name: Check for unused dependencies
-      run: cargo udeps || true

.github/workflows/test.yml

@@ -0,0 +1,139 @@
+name: Check
+
+on:
+  push:
+    branches: [ "*" ]
+  pull_request:
+    branches: [ "*" ]
+
+env:
+  CARGO_TERM_COLOR: always
+
+concurrency:
+  group: test-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+# ==========================
+# Formatting
+# ==========================
+  fmt:
+    name: Fmt
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt
+
+      - run: cargo fmt -- --check
+
+# ==========================
+# Tests
+# ==========================
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+      actions: write
+      checks: write
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache cargo
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/bin
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-nextest-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-nextest-
+            ${{ runner.os }}-cargo-
+
+      - name: Install cargo-nextest
+        run: cargo install --locked cargo-nextest || true
+
+      - name: Run tests with nextest
+        run: cargo nextest run -j "$(nproc)"
+
+# ==========================
+# Clippy
+# ==========================
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+      checks: write
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy
+
+      - name: Cache cargo
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-clippy-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-clippy-
+            ${{ runner.os }}-cargo-
+
+      - name: Run clippy
+        run: cargo clippy -j "$(nproc)" -- --cap-lints warn
+
+# ==========================
+# Udeps
+# ==========================
+  udeps:
+    name: Udeps
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rust-src
+
+      - name: Cache cargo
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/bin
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-udeps-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-udeps-
+            ${{ runner.os }}-cargo-
+
+      - name: Install cargo-udeps
+        run: cargo install --locked cargo-udeps || true
+
+      - name: Run udeps
+        run: cargo udeps -j "$(nproc)" || true

.gitignore

@@ -21,3 +21,4 @@ target
 #.idea/
 
 proxy-secret
+coverage-html/

AGENTS.md

@@ -5,6 +5,22 @@ Your responses are precise, minimal, and architecturally sound. You are working
 
 ---
 
+### Context: The Telemt Project
+
+You are working on **Telemt**, a high-performance, production-grade Telegram MTProxy implementation written in Rust. It is explicitly designed to operate in highly hostile network environments and evade advanced network censorship.
+
+**Adversarial Threat Model:**
+The proxy operates under constant surveillance by DPI (Deep Packet Inspection) systems and active scanners (state firewalls, mobile operator fraud controls). These entities actively probe IPs, analyze protocol handshakes, and look for known proxy signatures to block or throttle traffic.
+
+**Core Architectural Pillars:**
+1. **TLS-Fronting (TLS-F) & TCP-Splitting (TCP-S):** To the outside world, Telemt looks like a standard TLS server. If a client presents a valid MTProxy key, the connection is handled internally. If a censor's scanner, web browser, or unauthorized crawler connects, Telemt seamlessly splices the TCP connection (L4) to a real, legitimate HTTPS fallback server (e.g., Nginx) without modifying the `ClientHello` or terminating the TLS handshake.
+2. **Middle-End (ME) Orchestration:** A highly concurrent, generation-based pool managing upstream connections to Telegram Datacenters (DCs). It utilizes an **Adaptive Floor** (dynamically scaling writer connections based on traffic), **Hardswaps** (zero-downtime pool reconfiguration), and **STUN/NAT** reflection mechanisms. 
+3. **Strict KDF Routing:** Cryptographic Key Derivation Functions (KDF) in this protocol strictly rely on the exact pairing of Source IP/Port and Destination IP/Port. Deviations or missing port logic will silently break the MTProto handshake.
+4. **Data Plane vs. Control Plane Isolation:** The Data Plane (readers, writers, payload relay, TCP splicing) must remain strictly non-blocking, zero-allocation in hot paths, and highly resilient to network backpressure. The Control Plane (API, metrics, pool generation swaps, config reloads) orchestrates the state asynchronously without stalling the Data Plane.
+
+Any modification you make must preserve Telemt's invisibility to censors, its strict memory-safety invariants, and its hot-path throughput.
+
+
 ### 0. Priority Resolution — Scope Control
 
 This section resolves conflicts between code quality enforcement and scope limitation.
@@ -374,6 +390,12 @@ you MUST explain why existing invariants remain valid.
 - Do not modify existing tests unless the task explicitly requires it.
 - Do not weaken assertions.
 - Preserve determinism in testable components.
+- Bug-first forces the discipline of proving you understand a bug before you fix it. Tests written after a fix almost always pass trivially and catch nothing new.
+- Invariants over scenarios is the core shift. The route_mode table alone would have caught both BUG-1 and BUG-2 before they were written — "snapshot equals watch state after any transition burst" is a two-line property test that fails immediately on the current diverged-atomics code.
+- Differential/model catches logic drift over time.
+- Scheduler pressure is specifically aimed at the concurrent state bugs that keep reappearing. A single-threaded happy-path test of set_mode will never find subtle bugs; 10,000 concurrent calls will find it on the first run.
+- Mutation gate answers your original complaint directly. It measures test power. If you can remove a bounds check and nothing breaks, the suite isn't covering that branch yet — it just says so explicitly.
+- Dead parameter is a code smell rule. 
 
 ### 15. Security Constraints
 

CODE_OF_CONDUCT.md

@@ -1,8 +1,8 @@
 # Code of Conduct
 
-## 1. Purpose
+## Purpose
 
-Telemt exists to solve technical problems.
+**Telemt exists to solve technical problems.**
 
 Telemt is open to contributors who want to learn, improve and build meaningful systems together.
 
@@ -18,27 +18,34 @@ Technology has consequences. Responsibility is inherent.
 
 ---
 
-## 2. Principles
+## Principles
 
 * **Technical over emotional**
+
   Arguments are grounded in data, logs, reproducible cases, or clear reasoning.
 
 * **Clarity over noise**
+
   Communication is structured, concise, and relevant.
 
 * **Openness with standards**
+
   Participation is open. The work remains disciplined.
 
 * **Independence of judgment**
+
   Claims are evaluated on technical merit, not affiliation or posture.
 
 * **Responsibility over capability**
+
   Capability does not justify careless use.
 
 * **Cooperation over friction**
+
   Progress depends on coordination, mutual support, and honest review.
 
 * **Good intent, rigorous method**
+
   Assume good intent, but require rigor.
 
 > **Aussagen gelten nach ihrer Begründung.**
@@ -47,7 +54,7 @@ Technology has consequences. Responsibility is inherent.
 
 ---
 
-## 3. Expected Behavior
+## Expected Behavior
 
 Participants are expected to:
 
@@ -69,7 +76,7 @@ New contributors are welcome. They are expected to grow into these standards. Ex
 
 ---
 
-## 4. Unacceptable Behavior
+## Unacceptable Behavior
 
 The following is not allowed:
 
@@ -89,7 +96,7 @@ Such discussions may be closed, removed, or redirected.
 
 ---
 
-## 5. Security and Misuse
+## Security and Misuse
 
 Telemt is intended for responsible use.
 
@@ -109,15 +116,13 @@ Security is both technical and behavioral.
 
 Telemt is open to contributors of different backgrounds, experience levels, and working styles.
 
-Standards are public, legible, and applied to the work itself.
-
-Questions are welcome. Careful disagreement is welcome. Honest correction is welcome.
-
-Gatekeeping by obscurity, status signaling, or hostility is not.
+- Standards are public, legible, and applied to the work itself.
+- Questions are welcome. Careful disagreement is welcome. Honest correction is welcome.
+- Gatekeeping by obscurity, status signaling, or hostility is not.
 
 ---
 
-## 7. Scope
+## Scope
 
 This Code of Conduct applies to all official spaces:
 
@@ -127,16 +132,19 @@ This Code of Conduct applies to all official spaces:
 
 ---
 
-## 8. Maintainer Stewardship
+## Maintainer Stewardship
 
 Maintainers are responsible for final decisions in matters of conduct, scope, and direction.
 
-This responsibility is stewardship: preserving continuity, protecting signal, maintaining standards, and keeping Telemt workable for others.
+This responsibility is stewardship: 
+- preserving continuity, 
+- protecting signal, 
+- maintaining standards, 
+- keeping Telemt workable for others.
 
 Judgment should be exercised with restraint, consistency, and institutional responsibility.
-
-Not every decision requires extended debate.
-Not every intervention requires public explanation.
+- Not every decision requires extended debate.
+- Not every intervention requires public explanation.
 
 All decisions are expected to serve the durability, clarity, and integrity of Telemt.
 
@@ -146,7 +154,7 @@ All decisions are expected to serve the durability, clarity, and integrity of Te
 
 ---
 
-## 9. Enforcement
+## Enforcement
 
 Maintainers may act to preserve the integrity of Telemt, including by:
 
@@ -156,44 +164,40 @@ Maintainers may act to preserve the integrity of Telemt, including by:
 * Restricting or banning participants
 
 Actions are taken to maintain function, continuity, and signal quality.
-
-Where possible, correction is preferred to exclusion.
-
-Where necessary, exclusion is preferred to decay.
+- Where possible, correction is preferred to exclusion.
+- Where necessary, exclusion is preferred to decay.
 
 ---
 
-## 10. Final
+## Final
 
 Telemt is built on discipline, structure, and shared intent.
+- Signal over noise.
+- Facts over opinion.
+- Systems over rhetoric.
 
-Signal over noise.
-Facts over opinion.
-Systems over rhetoric.
+- Work is collective.
+- Outcomes are shared.
+- Responsibility is distributed.
 
-Work is collective.
-Outcomes are shared.
-Responsibility is distributed.
-
-Precision is learned.
-Rigor is expected.
-Help is part of the work.
+- Precision is learned.
+- Rigor is expected.
+- Help is part of the work.
 
 > **Ordnung ist Voraussetzung der Freiheit.**
 
-If you contribute — contribute with care.
-If you speak — speak with substance.
-If you engage — engage constructively.
+- If you contribute — contribute with care.
+- If you speak — speak with substance.
+- If you engage — engage constructively.
 
 ---
 
-## 11. After All
+## After All
 
 Systems outlive intentions.
-
-What is built will be used.
-What is released will propagate.
-What is maintained will define the future state.
+- What is built will be used.
+- What is released will propagate.
+- What is maintained will define the future state.
 
 There is no neutral infrastructure, only infrastructure shaped well or poorly.
 
@@ -201,8 +205,8 @@ There is no neutral infrastructure, only infrastructure shaped well or poorly.
 
 > Every system carries responsibility.
 
-Stability requires discipline.
-Freedom requires structure.
-Trust requires honesty.
+- Stability requires discipline.
+- Freedom requires structure.
+- Trust requires honesty.
 
-In the end, the system reflects its contributors.
+In the end: the system reflects its contributors.

Cargo.toml

@@ -1,8 +1,11 @@
 [package]
 name = "telemt"
-version = "3.3.28"
+version = "3.3.32"
 edition = "2024"
 
+[features]
+redteam_offline_expected_fail = []
+
 [dependencies]
 # C
 libc = "0.2"
@@ -22,17 +25,19 @@ hmac = "0.12"
 crc32fast = "1.4"
 crc32c = "0.6"
 zeroize = { version = "1.8", features = ["derive"] }
+subtle = "2.6"
+static_assertions = "1.1"
 
 # Network
-socket2 = { version = "0.5", features = ["all"] }
-nix = { version = "0.28", default-features = false, features = ["net"] }
+socket2 = { version = "0.6", features = ["all"] }
+nix = { version = "0.31", default-features = false, features = ["net", "fs"] }
 shadowsocks = { version = "1.24", features = ["aead-cipher-2022"] }
 
 # Serialization
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
-toml = "0.8"
-x509-parser = "0.15"
+toml = "1.0"
+x509-parser = "0.18"
 
 # Utils
 bytes = "1.9"
@@ -40,10 +45,10 @@ thiserror = "2.0"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 parking_lot = "0.12"
-dashmap = "5.5"
+dashmap = "6.1"
 arc-swap = "1.7"
 lru = "0.16"
-rand = "0.9"
+rand = "0.10"
 chrono = { version = "0.4", features = ["serde"] }
 hex = "0.4"
 base64 = "0.22"
@@ -52,23 +57,24 @@ regex = "1.11"
 crossbeam-queue = "0.3"
 num-bigint = "0.4"
 num-traits = "0.2"
+x25519-dalek = "2"
 anyhow = "1.0"
 
 # HTTP
-reqwest = { version = "0.12", features = ["rustls-tls"], default-features = false }
-notify = { version = "6", features = ["macos_fsevent"] }
-ipnetwork = "0.20"
+reqwest = { version = "0.13", features = ["rustls"], default-features = false }
+notify = "8.2"
+ipnetwork = { version = "0.21", features = ["serde"] }
 hyper = { version = "1", features = ["server", "http1"] }
 hyper-util = { version = "0.1", features = ["tokio", "server-auto"] }
 http-body-util = "0.1"
 httpdate = "1.0"
 tokio-rustls = { version = "0.26", default-features = false, features = ["tls12"] }
 rustls = { version = "0.23", default-features = false, features = ["std", "tls12", "ring"] }
-webpki-roots = "0.26"
+webpki-roots = "1.0"
 
 [dev-dependencies]
 tokio-test = "0.4"
-criterion = "0.5"
+criterion = "0.8"
 proptest = "1.4"
 futures = "0.3"
 
@@ -77,4 +83,6 @@ name = "crypto_bench"
 harness = false
 
 [profile.release]
-lto = "thin"
+lto = "fat"
+codegen-units = 1
+

Dockerfile

@@ -1,44 +1,98 @@
-# ==========================
-# Stage 1: Build
-# ==========================
-FROM rust:1.88-slim-bookworm AS builder
+# syntax=docker/dockerfile:1
 
-RUN apt-get update && apt-get install -y --no-install-recommends \
-    pkg-config \
-    && rm -rf /var/lib/apt/lists/*
-
-WORKDIR /build
-
-COPY Cargo.toml Cargo.lock* ./
-RUN mkdir src && echo 'fn main() {}' > src/main.rs && \
-    cargo build --release 2>/dev/null || true && \
-    rm -rf src
-
-COPY . .
-RUN cargo build --release && strip target/release/telemt
+ARG TELEMT_REPOSITORY=telemt/telemt
+ARG TELEMT_VERSION=latest
 
 # ==========================
-# Stage 2: Runtime
+# Minimal Image
 # ==========================
-FROM debian:bookworm-slim
+FROM debian:12-slim AS minimal
 
-RUN apt-get update && apt-get install -y --no-install-recommends \
+ARG TARGETARCH
+ARG TELEMT_REPOSITORY
+ARG TELEMT_VERSION
+
+RUN set -eux; \
+    apt-get update; \
+    apt-get install -y --no-install-recommends \
+        binutils \
         ca-certificates \
-    && rm -rf /var/lib/apt/lists/*
+        curl \
+        tar; \
+    rm -rf /var/lib/apt/lists/*
 
-RUN useradd -r -s /usr/sbin/nologin telemt
+RUN set -eux; \
+    case "${TARGETARCH}" in \
+        amd64) ASSET="telemt-x86_64-linux-musl.tar.gz" ;; \
+        arm64) ASSET="telemt-aarch64-linux-musl.tar.gz" ;; \
+        *) echo "Unsupported TARGETARCH: ${TARGETARCH}" >&2; exit 1 ;; \
+    esac; \
+    VERSION="${TELEMT_VERSION#refs/tags/}"; \
+    if [ -z "${VERSION}" ] || [ "${VERSION}" = "latest" ]; then \
+        BASE_URL="https://github.com/${TELEMT_REPOSITORY}/releases/latest/download"; \
+    else \
+        BASE_URL="https://github.com/${TELEMT_REPOSITORY}/releases/download/${VERSION}"; \
+    fi; \
+    curl -fL \
+        --retry 5 \
+        --retry-delay 3 \
+        --connect-timeout 10 \
+        --max-time 120 \
+        -o "/tmp/${ASSET}" \
+        "${BASE_URL}/${ASSET}"; \
+    curl -fL \
+        --retry 5 \
+        --retry-delay 3 \
+        --connect-timeout 10 \
+        --max-time 120 \
+        -o "/tmp/${ASSET}.sha256" \
+        "${BASE_URL}/${ASSET}.sha256"; \
+    cd /tmp; \
+    sha256sum -c "${ASSET}.sha256"; \
+    tar -xzf "${ASSET}" -C /tmp; \
+    test -f /tmp/telemt; \
+    install -m 0755 /tmp/telemt /telemt; \
+    strip --strip-unneeded /telemt || true; \
+    rm -f "/tmp/${ASSET}" "/tmp/${ASSET}.sha256" /tmp/telemt
+
+# ==========================
+# Debug Image
+# ==========================
+FROM debian:12-slim AS debug
+
+RUN set -eux; \
+    apt-get update; \
+    apt-get install -y --no-install-recommends \
+        ca-certificates \
+        tzdata \
+        curl \
+        iproute2 \
+        busybox; \
+    rm -rf /var/lib/apt/lists/*
 
 WORKDIR /app
 
-COPY --from=builder /build/target/release/telemt /app/telemt
+COPY --from=minimal /telemt /app/telemt
 COPY config.toml /app/config.toml
 
-RUN chown -R telemt:telemt /app
-USER telemt
-
-EXPOSE 443
-EXPOSE 9090
-EXPOSE 9091
+EXPOSE 443 9090 9091
+
+ENTRYPOINT ["/app/telemt"]
+CMD ["config.toml"]
+
+# ==========================
+# Production Distroless on MUSL
+# ==========================
+FROM gcr.io/distroless/static-debian12 AS prod
+
+WORKDIR /app
+
+COPY --from=minimal /telemt /app/telemt
+COPY config.toml /app/config.toml
+
+USER nonroot:nonroot
+
+EXPOSE 443 9090 9091
 
 ENTRYPOINT ["/app/telemt"]
 CMD ["config.toml"]

benches/crypto_bench.rs

@@ -1,5 +1,5 @@
 // Cryptobench
-use criterion::{black_box, criterion_group, Criterion};
+use criterion::{Criterion, black_box, criterion_group};
 
 fn bench_aes_ctr(c: &mut Criterion) {
     c.bench_function("aes_ctr_encrypt_64kb", |b| {

docs/CONFIG_PARAMS.en.md

@@ -20,7 +20,7 @@ This document lists all configuration keys accepted by `config.toml`.
 | Parameter | Type | Default | Constraints / validation | Description |
 |---|---|---|---|---|
 | data_path | `String \| null` | `null` | — | Optional runtime data directory path. |
-| prefer_ipv6 | `bool` | `false` | — | Prefer IPv6 where applicable in runtime logic. |
+| prefer_ipv6 | `bool` | `false` | Deprecated. Use `network.prefer`. | Deprecated legacy IPv6 preference flag migrated to `network.prefer`. |
 | fast_mode | `bool` | `true` | — | Enables fast-path optimizations for traffic processing. |
 | use_middle_proxy | `bool` | `true` | none | Enables ME transport mode; if `false`, runtime falls back to direct DC routing. |
 | proxy_secret_path | `String \| null` | `"proxy-secret"` | Path may be `null`. | Path to Telegram infrastructure proxy-secret file used by ME handshake logic. |
@@ -44,11 +44,14 @@ This document lists all configuration keys accepted by `config.toml`.
 | me_writer_cmd_channel_capacity | `usize` | `4096` | Must be `> 0`. | Capacity of per-writer command channel. |
 | me_route_channel_capacity | `usize` | `768` | Must be `> 0`. | Capacity of per-connection ME response route channel. |
 | me_c2me_channel_capacity | `usize` | `1024` | Must be `> 0`. | Capacity of per-client command queue (client reader -> ME sender). |
+| me_c2me_send_timeout_ms | `u64` | `4000` | `0..=60000`. | Maximum wait for enqueueing client->ME commands when the per-client queue is full (`0` keeps legacy unbounded wait). |
 | me_reader_route_data_wait_ms | `u64` | `2` | `0..=20`. | Bounded wait for routing ME DATA to per-connection queue (`0` = no wait). |
 | me_d2c_flush_batch_max_frames | `usize` | `32` | `1..=512`. | Max ME->client frames coalesced before flush. |
 | me_d2c_flush_batch_max_bytes | `usize` | `131072` | `4096..=2_097_152`. | Max ME->client payload bytes coalesced before flush. |
 | me_d2c_flush_batch_max_delay_us | `u64` | `500` | `0..=5000`. | Max microsecond wait for coalescing more ME->client frames (`0` disables timed coalescing). |
 | me_d2c_ack_flush_immediate | `bool` | `true` | — | Flushes client writer immediately after quick-ack write. |
+| me_quota_soft_overshoot_bytes | `u64` | `65536` | `0..=16_777_216`. | Extra per-route quota allowance (bytes) tolerated before writer-side quota enforcement drops route data. |
+| me_d2c_frame_buf_shrink_threshold_bytes | `usize` | `262144` | `4096..=16_777_216`. | Threshold for shrinking oversized ME->client frame-aggregation buffers after flush. |
 | direct_relay_copy_buf_c2s_bytes | `usize` | `65536` | `4096..=1_048_576`. | Copy buffer size for client->DC direction in direct relay. |
 | direct_relay_copy_buf_s2c_bytes | `usize` | `262144` | `8192..=2_097_152`. | Copy buffer size for DC->client direction in direct relay. |
 | crypto_pending_buffer | `usize` | `262144` | — | Max pending ciphertext buffer per client writer (bytes). |
@@ -105,6 +108,8 @@ This document lists all configuration keys accepted by `config.toml`.
 | me_warn_rate_limit_ms | `u64` | `5000` | Must be `> 0`. | Cooldown for repetitive ME warning logs (ms). |
 | me_route_no_writer_mode | `"async_recovery_failfast" \| "inline_recovery_legacy" \| "hybrid_async_persistent"` | `"hybrid_async_persistent"` | — | Route behavior when no writer is immediately available. |
 | me_route_no_writer_wait_ms | `u64` | `250` | `10..=5000`. | Max wait in async-recovery failfast mode (ms). |
+| me_route_hybrid_max_wait_ms | `u64` | `3000` | `50..=60000`. | Maximum cumulative wait in hybrid no-writer mode before failfast fallback (ms). |
+| me_route_blocking_send_timeout_ms | `u64` | `250` | `0..=5000`. | Maximum wait for blocking route-channel send fallback (`0` keeps legacy unbounded wait). |
 | me_route_inline_recovery_attempts | `u32` | `3` | Must be `> 0`. | Inline recovery attempts in legacy mode. |
 | me_route_inline_recovery_wait_ms | `u64` | `3000` | `10..=30000`. | Max inline recovery wait in legacy mode (ms). |
 | fast_mode_min_tls_record | `usize` | `0` | — | Minimum TLS record size when fast-mode coalescing is enabled (`0` disables). |
@@ -124,6 +129,7 @@ This document lists all configuration keys accepted by `config.toml`.
 | me_secret_atomic_snapshot | `bool` | `true` | — | Keeps selector and secret bytes from the same snapshot atomically. |
 | proxy_secret_len_max | `usize` | `256` | Must be within `[32, 4096]`. | Upper length limit for accepted proxy-secret bytes. |
 | me_pool_drain_ttl_secs | `u64` | `90` | none | Time window where stale writers remain fallback-eligible after map change. |
+| me_instadrain | `bool` | `false` | — | Forces draining stale writers to be removed on the next cleanup tick, bypassing TTL/deadline waiting. |
 | me_pool_drain_threshold | `u64` | `128` | — | Max draining stale writers before batch force-close (`0` disables threshold cleanup). |
 | me_pool_drain_soft_evict_enabled | `bool` | `true` | — | Enables gradual soft-eviction of stale writers during drain/reinit instead of immediate hard close. |
 | me_pool_drain_soft_evict_grace_secs | `u64` | `30` | `0..=3600`. | Grace period before stale writers become soft-evict candidates. |
@@ -198,10 +204,14 @@ This document lists all configuration keys accepted by `config.toml`.
 | listen_tcp | `bool \| null` | `null` (auto) | — | Explicit TCP listener enable/disable override. |
 | proxy_protocol | `bool` | `false` | — | Enables HAProxy PROXY protocol parsing on incoming client connections. |
 | proxy_protocol_header_timeout_ms | `u64` | `500` | Must be `> 0`. | Timeout for PROXY protocol header read/parse (ms). |
+| proxy_protocol_trusted_cidrs | `IpNetwork[]` | `[]` | — | When non-empty, only connections from these proxy source CIDRs are allowed to provide PROXY protocol headers. If empty, PROXY headers are rejected by default (security hardening). |
 | metrics_port | `u16 \| null` | `null` | — | Metrics endpoint port (enables metrics listener). |
 | metrics_listen | `String \| null` | `null` | — | Full metrics bind address (`IP:PORT`), overrides `metrics_port`. |
 | metrics_whitelist | `IpNetwork[]` | `["127.0.0.1/32", "::1/128"]` | — | CIDR whitelist for metrics endpoint access. |
 | max_connections | `u32` | `10000` | — | Max concurrent client connections (`0` = unlimited). |
+| accept_permit_timeout_ms | `u64` | `250` | `0..=60000`. | Maximum wait for acquiring a connection-slot permit before the accepted connection is dropped (`0` keeps legacy unbounded wait). |
+
+Note: When `server.proxy_protocol` is enabled, incoming PROXY protocol headers are parsed from the first bytes of the connection and the client source address is replaced with `src_addr` from the header. For security, the peer source IP (the direct connection address) is verified against `server.proxy_protocol_trusted_cidrs`; if this list is empty, PROXY headers are rejected and the connection is considered untrusted. 
 
 ## [server.api]
 
@@ -226,7 +236,7 @@ This document lists all configuration keys accepted by `config.toml`.
 |---|---|---|---|---|
 | ip | `IpAddr` | — | — | Listener bind IP. |
 | announce | `String \| null` | — | — | Public IP/domain announced in proxy links (priority over `announce_ip`). |
-| announce_ip | `IpAddr \| null` | — | — | Deprecated legacy announce IP (migrated to `announce` if needed). |
+| announce_ip | `IpAddr \| null` | — | Deprecated. Use `announce`. | Deprecated legacy announce IP (migrated to `announce` if needed). |
 | proxy_protocol | `bool \| null` | `null` | — | Per-listener override for PROXY protocol enable flag. |
 | reuse_allow | `bool` | `false` | — | Enables `SO_REUSEPORT` for multi-instance bind sharing. |
 
@@ -235,6 +245,10 @@ This document lists all configuration keys accepted by `config.toml`.
 | Parameter | Type | Default | Constraints / validation | Description |
 |---|---|---|---|---|
 | client_handshake | `u64` | `30` | — | Client handshake timeout. |
+| relay_idle_policy_v2_enabled | `bool` | `true` | — | Enables soft/hard middle-relay client idle policy. |
+| relay_client_idle_soft_secs | `u64` | `120` | Must be `> 0`; must be `<= relay_client_idle_hard_secs`. | Soft idle threshold for middle-relay client uplink inactivity (seconds). |
+| relay_client_idle_hard_secs | `u64` | `360` | Must be `> 0`; must be `>= relay_client_idle_soft_secs`. | Hard idle threshold for middle-relay client uplink inactivity (seconds). |
+| relay_idle_grace_after_downstream_activity_secs | `u64` | `30` | Must be `<= relay_client_idle_hard_secs`. | Extra hard-idle grace after recent downstream activity (seconds). |
 | tg_connect | `u64` | `10` | — | Upstream Telegram connect timeout. |
 | client_keepalive | `u64` | `15` | — | Client keepalive timeout. |
 | client_ack | `u64` | `90` | — | Client ACK timeout. |
@@ -247,6 +261,9 @@ This document lists all configuration keys accepted by `config.toml`.
 |---|---|---|---|---|
 | tls_domain | `String` | `"petrovich.ru"` | — | Primary TLS domain used in fake TLS handshake profile. |
 | tls_domains | `String[]` | `[]` | — | Additional TLS domains for generating multiple links. |
+| unknown_sni_action | `"drop" \| "mask"` | `"drop"` | — | Action for TLS ClientHello with unknown/non-configured SNI. |
+| tls_fetch_scope | `String` | `""` | Value is trimmed during load; empty keeps default upstream routing behavior. | Upstream scope tag used for TLS-front metadata fetches. |
+| tls_fetch | `Table` | built-in defaults | See `[censorship.tls_fetch]` section below. | TLS-front metadata fetch strategy settings. |
 | mask | `bool` | `true` | — | Enables masking/fronting relay mode. |
 | mask_host | `String \| null` | `null` | — | Upstream mask host for TLS fronting relay. |
 | mask_port | `u16` | `443` | — | Upstream mask port for TLS fronting relay. |
@@ -260,6 +277,143 @@ This document lists all configuration keys accepted by `config.toml`.
 | tls_full_cert_ttl_secs | `u64` | `90` | — | TTL for sending full cert payload per (domain, client IP) tuple. |
 | alpn_enforce | `bool` | `true` | — | Enforces ALPN echo behavior based on client preference. |
 | mask_proxy_protocol | `u8` | `0` | — | PROXY protocol mode for mask backend (`0` disabled, `1` v1, `2` v2). |
+| mask_shape_hardening | `bool` | `true` | — | Enables client->mask shape-channel hardening by applying controlled tail padding to bucket boundaries on mask relay shutdown. |
+| mask_shape_hardening_aggressive_mode | `bool` | `false` | Requires `mask_shape_hardening = true`. | Opt-in aggressive shaping profile: allows shaping on backend-silent non-EOF paths and switches above-cap blur to strictly positive random tail. |
+| mask_shape_bucket_floor_bytes | `usize` | `512` | Must be `> 0`; should be `<= mask_shape_bucket_cap_bytes`. | Minimum bucket size used by shape-channel hardening. |
+| mask_shape_bucket_cap_bytes | `usize` | `4096` | Must be `>= mask_shape_bucket_floor_bytes`. | Maximum bucket size used by shape-channel hardening; traffic above cap is not padded further. |
+| mask_shape_above_cap_blur | `bool` | `false` | Requires `mask_shape_hardening = true`; requires `mask_shape_above_cap_blur_max_bytes > 0`. | Adds bounded randomized tail bytes even when forwarded size already exceeds cap. |
+| mask_shape_above_cap_blur_max_bytes | `usize` | `512` | Must be `<= 1048576`; must be `> 0` when `mask_shape_above_cap_blur = true`. | Maximum randomized extra bytes appended above cap. |
+| mask_relay_max_bytes | `usize` | `5242880` | Must be `> 0`; must be `<= 67108864`. | Maximum relayed bytes per direction on unauthenticated masking fallback path. |
+| mask_classifier_prefetch_timeout_ms | `u64` | `5` | Must be within `[5, 50]`. | Timeout budget (ms) for extending fragmented initial classifier window on masking fallback. |
+| mask_timing_normalization_enabled | `bool` | `false` | Requires `mask_timing_normalization_floor_ms > 0`; requires `ceiling >= floor`. | Enables timing envelope normalization on masking outcomes. |
+| mask_timing_normalization_floor_ms | `u64` | `0` | Must be `> 0` when timing normalization is enabled; must be `<= ceiling`. | Lower bound (ms) for masking outcome normalization target. |
+| mask_timing_normalization_ceiling_ms | `u64` | `0` | Must be `>= floor`; must be `<= 60000`. | Upper bound (ms) for masking outcome normalization target. |
+
+## [censorship.tls_fetch]
+
+| Parameter | Type | Default | Constraints / validation | Description |
+|---|---|---|---|---|
+| profiles | `("modern_chrome_like" \| "modern_firefox_like" \| "compat_tls12" \| "legacy_minimal")[]` | `["modern_chrome_like", "modern_firefox_like", "compat_tls12", "legacy_minimal"]` | Empty list falls back to defaults; values are deduplicated preserving order. | Ordered ClientHello profile fallback chain for TLS-front metadata fetch. |
+| strict_route | `bool` | `true` | — | Fails closed on upstream-route connect errors instead of falling back to direct TCP when route is configured. |
+| attempt_timeout_ms | `u64` | `5000` | Must be `> 0`. | Timeout budget per one TLS-fetch profile attempt (ms). |
+| total_budget_ms | `u64` | `15000` | Must be `> 0`. | Total wall-clock budget across all TLS-fetch attempts (ms). |
+| grease_enabled | `bool` | `false` | — | Enables GREASE-style random values in selected ClientHello extensions for fetch traffic. |
+| deterministic | `bool` | `false` | — | Enables deterministic ClientHello randomness for debugging/tests. |
+| profile_cache_ttl_secs | `u64` | `600` | `0` disables cache. | TTL for winner-profile cache entries used by TLS fetch path. |
+
+### Shape-channel hardening notes (`[censorship]`)
+
+These parameters are designed to reduce one specific fingerprint source during masking: the exact number of bytes sent from proxy to `mask_host` for invalid or probing traffic.
+
+Without hardening, a censor can often correlate probe input length with backend-observed length very precisely (for example: `5 + body_sent` on early TLS reject paths). That creates a length-based classifier signal.
+
+When `mask_shape_hardening = true`, Telemt pads the **client->mask** stream tail to a bucket boundary at relay shutdown:
+
+- Total bytes sent to mask are first measured.
+- A bucket is selected using powers of two starting from `mask_shape_bucket_floor_bytes`.
+- Padding is added only if total bytes are below `mask_shape_bucket_cap_bytes`.
+- If bytes already exceed cap, no extra padding is added.
+
+This means multiple nearby probe sizes collapse into the same backend-observed size class, making active classification harder.
+
+What each parameter changes in practice:
+
+- `mask_shape_hardening`
+	Enables or disables this entire length-shaping stage on the fallback path.
+	When `false`, backend-observed length stays close to the real forwarded probe length.
+	When `true`, clean relay shutdown can append random padding bytes to move the total into a bucket.
+
+- `mask_shape_bucket_floor_bytes`
+	Sets the first bucket boundary used for small probes.
+	Example: with floor `512`, a malformed probe that would otherwise forward `37` bytes can be expanded to `512` bytes on clean EOF.
+	Larger floor values hide very small probes better, but increase egress cost.
+
+- `mask_shape_bucket_cap_bytes`
+	Sets the largest bucket Telemt will pad up to with bucket logic.
+	Example: with cap `4096`, a forwarded total of `1800` bytes may be padded to `2048` or `4096` depending on the bucket ladder, but a total already above `4096` will not be bucket-padded further.
+	Larger cap values increase the range over which size classes are collapsed, but also increase worst-case overhead.
+
+- Clean EOF matters in conservative mode
+	In the default profile, shape padding is intentionally conservative: it is applied on clean relay shutdown, not on every timeout/drip path.
+	This avoids introducing new timeout-tail artifacts that some backends or tests interpret as a separate fingerprint.
+
+Practical trade-offs:
+
+- Better anti-fingerprinting on size/shape channel.
+- Slightly higher egress overhead for small probes due to padding.
+- Behavior is intentionally conservative and enabled by default.
+
+Recommended starting profile:
+
+- `mask_shape_hardening = true` (default)
+- `mask_shape_bucket_floor_bytes = 512`
+- `mask_shape_bucket_cap_bytes = 4096`
+
+### Aggressive mode notes (`[censorship]`)
+
+`mask_shape_hardening_aggressive_mode` is an opt-in profile for higher anti-classifier pressure.
+
+- Default is `false` to preserve conservative timeout/no-tail behavior.
+- Requires `mask_shape_hardening = true`.
+- When enabled, backend-silent non-EOF masking paths may be shaped.
+- When enabled together with above-cap blur, the random extra tail uses `[1, max]` instead of `[0, max]`.
+
+What changes when aggressive mode is enabled:
+
+- Backend-silent timeout paths can be shaped
+	In default mode, a client that keeps the socket half-open and times out will usually not receive shape padding on that path.
+	In aggressive mode, Telemt may still shape that backend-silent session if no backend bytes were returned.
+	This is specifically aimed at active probes that try to avoid EOF in order to preserve an exact backend-observed length.
+
+- Above-cap blur always adds at least one byte
+	In default mode, above-cap blur may choose `0`, so some oversized probes still land on their exact base forwarded length.
+	In aggressive mode, that exact-base sample is removed by construction.
+
+- Tradeoff
+	Aggressive mode improves resistance to active length classifiers, but it is more opinionated and less conservative.
+	If your deployment prioritizes strict compatibility with timeout/no-tail semantics, leave it disabled.
+	If your threat model includes repeated active probing by a censor, this mode is the stronger profile.
+
+Use this mode only when your threat model prioritizes classifier resistance over strict compatibility with conservative masking semantics.
+
+### Above-cap blur notes (`[censorship]`)
+
+`mask_shape_above_cap_blur` adds a second-stage blur for very large probes that are already above `mask_shape_bucket_cap_bytes`.
+
+- A random tail in `[0, mask_shape_above_cap_blur_max_bytes]` is appended in default mode.
+- In aggressive mode, the random tail becomes strictly positive: `[1, mask_shape_above_cap_blur_max_bytes]`.
+- This reduces exact-size leakage above cap at bounded overhead.
+- Keep `mask_shape_above_cap_blur_max_bytes` conservative to avoid unnecessary egress growth.
+
+Operational meaning:
+
+- Without above-cap blur
+	A probe that forwards `5005` bytes will still look like `5005` bytes to the backend if it is already above cap.
+
+- With above-cap blur enabled
+	That same probe may look like any value in a bounded window above its base length.
+	Example with `mask_shape_above_cap_blur_max_bytes = 64`:
+	backend-observed size becomes `5005..5069` in default mode, or `5006..5069` in aggressive mode.
+
+- Choosing `mask_shape_above_cap_blur_max_bytes`
+	Small values reduce cost but preserve more separability between far-apart oversized classes.
+	Larger values blur oversized classes more aggressively, but add more egress overhead and more output variance.
+
+### Timing normalization envelope notes (`[censorship]`)
+
+`mask_timing_normalization_enabled` smooths timing differences between masking outcomes by applying a target duration envelope.
+
+- A random target is selected in `[mask_timing_normalization_floor_ms, mask_timing_normalization_ceiling_ms]`.
+- Fast paths are delayed up to the selected target.
+- Slow paths are not forced to finish by the ceiling (the envelope is best-effort shaping, not truncation).
+
+Recommended starting profile for timing shaping:
+
+- `mask_timing_normalization_enabled = true`
+- `mask_timing_normalization_floor_ms = 180`
+- `mask_timing_normalization_ceiling_ms = 320`
+
+If your backend or network is very bandwidth-constrained, reduce cap first. If probes are still too distinguishable in your environment, increase floor gradually.
 
 ## [access]
 

docs/FAQ.en.md

@@ -3,7 +3,7 @@
 1. Go to @MTProxybot bot.
 2. Enter the command `/newproxy`
 3. Send the server IP and port. For example: 1.2.3.4:443
-4. Open the config `nano /etc/telemt.toml`.
+4. Open the config `nano /etc/telemt/telemt.toml`.
 5. Copy and send the user secret from the [access.users] section to the bot.
 6. Copy the tag received from the bot. For example 1234567890abcdef1234567890abcdef.
 > [!WARNING]
@@ -33,6 +33,9 @@ hello = "ad_tag"
 hello2 = "ad_tag2"
 ```
 
+## Why is middle proxy (ME) needed
+https://github.com/telemt/telemt/discussions/167
+
 ## How many people can use 1 link
 
 By default, 1 link can be used by any number of people.  
@@ -60,9 +63,12 @@ user3 = "00000000000000000000000000000003"
 curl -s http://127.0.0.1:9091/v1/users | jq
 ```
 
+## "Unknown TLS SNI" Error
+You probably updated tls_domain, but users are still connecting via old links with the previous domain.
+
 ## How to view metrics
 
-1. Open the config `nano /etc/telemt.toml`
+1. Open the config `nano /etc/telemt/telemt.toml`
 2. Add the following parameters
 ```toml
 [server]

docs/FAQ.ru.md

@@ -3,7 +3,7 @@
 1. Зайти в бота @MTProxybot.
 2. Ввести команду `/newproxy`
 3. Отправить IP и порт сервера. Например: 1.2.3.4:443
-4. Открыть конфиг `nano /etc/telemt.toml`.
+4. Открыть конфиг `nano /etc/telemt/telemt.toml`.
 5. Скопировать и отправить боту секрет пользователя из раздела [access.users].
 6. Скопировать полученный tag у бота. Например 1234567890abcdef1234567890abcdef.
 > [!WARNING]
@@ -33,6 +33,10 @@ hello = "ad_tag"
 hello2 = "ad_tag2"
 ```
 
+## Зачем нужен middle proxy (ME)
+https://github.com/telemt/telemt/discussions/167
+
+
 ## Сколько человек может пользоваться 1 ссылкой
 
 По умолчанию 1 ссылкой может пользоваться сколько угодно человек.  
@@ -60,9 +64,12 @@ user3 = "00000000000000000000000000000003"
 curl -s http://127.0.0.1:9091/v1/users | jq
 ```
 
+## Ошибка "Unknown TLS SNI"
+Возможно, вы обновили tls_domain, но пользователи всё ещё пытаются подключаться по старым ссылкам с прежним доменом.
+
 ## Как посмотреть метрики
 
-1. Открыть конфиг `nano /etc/telemt.toml`
+1. Открыть конфиг `nano /etc/telemt/telemt.toml`
 2. Добавить следующие параметры
 ```toml
 [server]

docs/QUICK_START_GUIDE.en.md

@@ -27,12 +27,12 @@ chmod +x /bin/telemt
 
 **0. Check port and generate secrets**
 
-The port you have selected for use should be MISSING from the list, when:
+The port you have selected for use should not be in the list:
 ```bash
 netstat -lnp
 ```
 
-Generate 16 bytes/32 characters HEX with OpenSSL or another way:
+Generate 16 bytes/32 characters in HEX format with OpenSSL or another way:
 ```bash
 openssl rand -hex 16
 ```
@@ -50,7 +50,7 @@ Save the obtained result somewhere. You will need it later!
 
 **1. Place your config to /etc/telemt/telemt.toml**
 
-Create config directory:
+Create the config directory:
 ```bash
 mkdir /etc/telemt
 ```
@@ -59,7 +59,7 @@ Open nano
 ```bash
 nano /etc/telemt/telemt.toml
 ```
-paste your config
+Insert your configuration:
 
 ```toml
 # === General Settings ===
@@ -94,7 +94,8 @@ then Ctrl+S -> Ctrl+X to save
 
 > [!WARNING]
 > Replace the value of the hello parameter with the value you obtained in step 0.  
-> Replace the value of the tls_domain parameter with another website.
+> Additionally, change the value of the tls_domain parameter to a different website.
+> Changing the tls_domain parameter will break all links that use the old domain!
 
 ---
 
@@ -105,14 +106,14 @@ useradd -d /opt/telemt -m -r -U telemt
 chown -R telemt:telemt /etc/telemt
 ```
 
-**3. Create service on /etc/systemd/system/telemt.service**
+**3. Create service in /etc/systemd/system/telemt.service**
 
 Open nano
 ```bash
 nano /etc/systemd/system/telemt.service
 ```
 
-paste this Systemd Module
+Insert this Systemd module:
 ```bash
 [Unit]
 Description=Telemt
@@ -147,13 +148,16 @@ systemctl daemon-reload
 
 **6.** For automatic startup at system boot, enter `systemctl enable telemt`
 
-**7.** To get the link(s), enter
+**7.** To get the link(s), enter:
 ```bash
 curl -s http://127.0.0.1:9091/v1/users | jq
 ```
 
 > Any number of people can use one link.
 
+> [!WARNING]
+> Only the command from step 7 can provide a working link. Do not try to create it yourself or copy it from anywhere if you are not sure what you are doing!
+
 ---
 
 # Telemt via Docker Compose

docs/QUICK_START_GUIDE.ru.md

@@ -95,6 +95,7 @@ hello = "00000000000000000000000000000000"
 > [!WARNING]
 > Замените значение параметра hello на значение, которое вы получили в пункте 0.  
 > Так же замените значение параметра tls_domain на другой сайт.
+> Изменение параметра tls_domain сделает нерабочими все ссылки, использующие старый домен!
 
 ---
 
@@ -178,7 +179,7 @@ docker compose down
 > - По умолчанию публикуются порты 443:443, а контейнер запускается со сброшенными привилегиями (добавлена только `NET_BIND_SERVICE`)  
 > - Если вам действительно нужна сеть хоста (обычно это требуется только для некоторых конфигураций IPv6), раскомментируйте `network_mode: host`
 
-**Запуск в Docker Compose**
+**Запуск без Docker Compose**
 ```bash
 docker build -t telemt:local .
 docker run --name telemt --restart unless-stopped \

docs/VPS_DOUBLE_HOP.en.md

@@ -0,0 +1,287 @@
+<img src="https://gist.githubusercontent.com/avbor/1f8a128e628f47249aae6e058a57610b/raw/19013276c035e91058e0a9799ab145f8e70e3ff5/scheme.svg">
+
+## Concept
+- **Server A** (__conditionally Russian Federation_):\
+  Entry point, receives Telegram proxy user traffic via **HAProxy** (port `443`)\
+  and sends it to the tunnel to Server **B**.\
+  Internal IP in the tunnel — `10.10.10.2`\
+  Port for HAProxy clients — `443\tcp`
+- **Server B** (_conditionally Netherlands_):\
+  Exit point, runs **telemt** and accepts client connections through Server **A**.\
+  The server must have unrestricted access to Telegram servers.\
+  Internal IP in the tunnel — `10.10.10.1`\
+  AmneziaWG port — `8443\udp`\
+  Port for telemt clients — `443\tcp`
+
+---
+
+## Step 1. Setting up the AmneziaWG tunnel (A <-> B)
+[AmneziaWG](https://github.com/amnezia-vpn/amneziawg-linux-kernel-module) must be installed on all servers.\
+All following commands are given for **Ubuntu 24.04**.\
+For RHEL-based distributions, installation instructions are available at the link above.
+
+### Installing AmneziaWG (Servers A and B)
+The following steps must be performed on each server:
+
+#### 1. Adding the AmneziaWG repository and installing required packages:
+```bash
+sudo apt install -y software-properties-common python3-launchpadlib gnupg2 linux-headers-$(uname -r) && \
+sudo add-apt-repository ppa:amnezia/ppa && \
+sudo apt-get install -y amneziawg
+```
+
+#### 2. Generating a unique key pair:
+```bash
+cd /etc/amnezia/amneziawg && \
+awg genkey | tee private.key | awg pubkey > public.key
+```
+
+As a result, you will get two files in the `/etc/amnezia/amneziawg` folder:\
+`private.key` - private, and\
+`public.key` - public server keys
+
+#### 3. Configuring network interfaces:
+Obfuscation parameters `S1`, `S2`, `H1`, `H2`, `H3`, `H4` must be strictly identical on both servers.\
+Parameters `Jc`, `Jmin` and `Jmax` can differ.\
+Parameters `I1-I5` ([Custom Protocol Signature](https://docs.amnezia.org/documentation/amnezia-wg/)) must be specified on the client side (Server **A**).
+
+Recommendations for choosing values:
+
+```text
+Jc — 1 ≤ Jc ≤ 128; from 4 to 12 inclusive
+Jmin — Jmax > Jmin < 1280*; recommended 8
+Jmax — Jmin < Jmax ≤ 1280*; recommended 80
+S1 — S1 ≤ 1132* (1280* - 148 = 1132); S1 + 56 ≠ S2;
+recommended range from 15 to 150 inclusive
+S2 — S2 ≤ 1188* (1280* - 92 = 1188);
+recommended range from 15 to 150 inclusive
+H1/H2/H3/H4 — must be unique and differ from each other;
+recommended range from 5 to 2147483647 inclusive
+
+* It is assumed that the Internet connection has an MTU of 1280.
+```
+
+> [!IMPORTANT]
+> It is recommended to use your own, unique values.\
+> You can use the [generator](https://htmlpreview.github.io/?https://gist.githubusercontent.com/avbor/955782b5c37b06240b243aa375baeac5/raw/13f5517ca473b47c412b9a99407066de973732bd/awg-gen.html) to select parameters.
+
+#### Server B Configuration (Netherlands):
+
+Create the interface configuration file (`awg0`)
+```bash
+nano /etc/amnezia/amneziawg/awg0.conf
+```
+
+File content
+```ini
+[Interface]
+Address = 10.10.10.1/24
+ListenPort = 8443
+PrivateKey = <PRIVATE_KEY_SERVER_B>
+SaveConfig = true
+Jc = 4
+Jmin = 8
+Jmax = 80
+S1 = 29
+S2 = 15
+S3 = 18
+S4 = 0
+H1 = 2087563914
+H2 = 188817757
+H3 = 101784570
+H4 = 432174303
+
+[Peer]
+PublicKey = <PUBLIC_KEY_SERVER_A>
+AllowedIPs = 10.10.10.2/32
+```
+`ListenPort` - the port on which the server will wait for connections, you can choose any free one.\
+`<PRIVATE_KEY_SERVER_B>` - the content of the `private.key` file from Server **B**.\
+`<PUBLIC_KEY_SERVER_A>` - the content of the `public.key` file from Server **A**.
+
+Open the port on the firewall (if enabled):
+```bash
+sudo ufw allow from <PUBLIC_IP_SERVER_A> to any port 8443 proto udp
+```
+
+`<PUBLIC_IP_SERVER_A>` - the external IP address of Server **A**.
+
+#### Server A Configuration (Russian Federation):
+Create the interface configuration file (awg0)
+
+```bash
+nano /etc/amnezia/amneziawg/awg0.conf
+```
+
+File content
+```ini
+[Interface]
+Address = 10.10.10.2/24
+PrivateKey = <PRIVATE_KEY_SERVER_A>
+Jc = 4
+Jmin = 8
+Jmax = 80
+S1 = 29
+S2 = 15
+S3 = 18
+S4 = 0
+H1 = 2087563914
+H2 = 188817757
+H3 = 101784570
+H4 = 432174303
+I1 = <b 0xc10000000108981eba846e21f74e00>
+I2 = <b 0xc20000000108981eba846e21f74e00>
+I3 = <b 0xc30000000108981eba846e21f74e00>
+I4 = <b 0x43981eba846e21f74e>
+I5 = <b 0x43981eba846e21f74e>
+
+[Peer]
+PublicKey = <PUBLIC_KEY_SERVER_B>
+Endpoint = <PUBLIC_IP_SERVER_B>:8443
+AllowedIPs = 10.10.10.1/32
+PersistentKeepalive = 25
+```
+
+`<PRIVATE_KEY_SERVER_A>` - the content of the `private.key` file from Server **A**.\
+`<PUBLIC_KEY_SERVER_B>` - the content of the `public.key` file from Server **B**.\
+`<PUBLIC_IP_SERVER_B>` - the public IP address of Server **B**.
+
+Enable the tunnel on both servers:
+```bash
+sudo systemctl enable --now awg-quick@awg0
+```
+
+Make sure Server B is accessible from Server A through the tunnel.
+```bash
+ping 10.10.10.1
+PING 10.10.10.1 (10.10.10.1) 56(84) bytes of data.
+64 bytes from 10.10.10.1: icmp_seq=1 ttl=64 time=35.1 ms
+64 bytes from 10.10.10.1: icmp_seq=2 ttl=64 time=35.0 ms
+64 bytes from 10.10.10.1: icmp_seq=3 ttl=64 time=35.1 ms
+^C
+```
+---
+
+## Step 2. Installing telemt on Server B (conditionally Netherlands)
+Installation and configuration are described [here](https://github.com/telemt/telemt/blob/main/docs/QUICK_START_GUIDE.ru.md) or [here](https://gitlab.com/An0nX/telemt-docker#-quick-start-docker-compose).\
+It is assumed that telemt expects connections on port `443\tcp`.
+
+In the telemt config, you must enable the `Proxy` protocol and restrict connections to it only through the tunnel.
+```toml
+[server]
+port = 443
+listen_addr_ipv4 = "10.10.10.1"
+proxy_protocol = true
+```
+
+Also, for correct link generation, specify the FQDN or IP address and port of Server `A`
+```toml
+[general.links]
+show = "*"
+public_host = "<FQDN_OR_IP_SERVER_A>"
+public_port = 443
+```
+
+Open the port on the firewall (if enabled):
+```bash
+sudo ufw allow from 10.10.10.2 to any port 443 proto tcp
+```
+
+---
+
+## Step 3. Configuring HAProxy on Server A (Russian Federation)
+Since the version in the standard Ubuntu repository is relatively old, it makes sense to use the official Docker image.\
+[Instructions](https://docs.docker.com/engine/install/ubuntu/) for installing Docker on Ubuntu.
+
+> [!WARNING]
+> By default, regular users do not have rights to use ports < 1024.
+> Attempts to run HAProxy on port 443 can lead to errors:
+> ```
+> [ALERT] (8) : Binding [/usr/local/etc/haproxy/haproxy.cfg:17] for frontend tcp_in_443: 
+> protocol tcpv4: cannot bind socket (Permission denied) for [0.0.0.0:443].
+> ```
+> There are two simple ways to bypass this restriction, choose one:
+> 1. At the OS level, change the net.ipv4.ip_unprivileged_port_start setting to allow users to use all ports:
+> ```
+> echo "net.ipv4.ip_unprivileged_port_start = 0" | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
+> ```
+> or
+> 
+> 2. Run HAProxy as root:
+> Uncomment the `user: "root"` parameter in docker-compose.yaml.
+
+#### Create a folder for HAProxy:
+```bash
+mkdir -p /opt/docker-compose/haproxy && cd $_
+```
+
+#### Create the docker-compose.yaml file
+`nano docker-compose.yaml`
+
+File content
+```yaml
+services:
+  haproxy:
+    image: haproxy:latest
+    container_name: haproxy
+    restart: unless-stopped
+    # user: "root"
+    network_mode: "host"
+    volumes:
+      - ./haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg:ro
+    logging:
+      driver: "json-file"
+      options:
+        max-size: "1m"
+        max-file: "1"
+```
+
+#### Create the haproxy.cfg config file
+Accept connections on port 443\tcp and send them through the tunnel to Server `B` 10.10.10.1:443
+
+`nano haproxy.cfg`
+
+File content
+
+```haproxy
+global
+    log stdout format raw local0
+    maxconn 10000
+
+defaults
+    log     global
+    mode    tcp
+    option  tcplog
+    option  clitcpka
+    option  srvtcpka
+    timeout connect 5s
+    timeout client  2h
+    timeout server  2h
+    timeout check   5s
+
+frontend tcp_in_443
+    bind *:443
+    maxconn 8000
+    option tcp-smart-accept
+    default_backend telemt_nodes
+
+backend telemt_nodes
+    option tcp-smart-connect
+    server server_a 10.10.10.1:443 check inter 5s rise 2 fall 3 send-proxy-v2
+
+
+```
+> [!WARNING]
+> **The file must end with an empty line, otherwise HAProxy will not start!**
+
+#### Allow port 443\tcp in the firewall (if enabled)
+```bash
+sudo ufw allow 443/tcp
+```
+
+#### Start the HAProxy container
+```bash
+docker compose up -d
+```
+
+If everything is configured correctly, you can now try connecting Telegram clients using links from the telemt log\api.

docs/VPS_DOUBLE_HOP.ru.md

@@ -0,0 +1,291 @@
+<img src="https://gist.githubusercontent.com/avbor/1f8a128e628f47249aae6e058a57610b/raw/19013276c035e91058e0a9799ab145f8e70e3ff5/scheme.svg">
+
+## Концепция
+- **Сервер A** (_РФ_):\
+  Точка входа, принимает трафик пользователей Telegram-прокси через **HAProxy** (порт `443`)\
+  и отправляет в туннель на Сервер **B**.\
+  Внутренний IP в туннеле — `10.10.10.2`\
+  Порт для клиентов HAProxy — `443\tcp`
+- **Сервер B** (_условно Нидерланды_):\
+  Точка выхода, на нем работает **telemt** и принимает подключения клиентов через Сервер **A**.\
+  На сервере должен быть неограниченный доступ до серверов Telegram.\
+  Внутренний IP в туннеле — `10.10.10.1`\
+  Порт AmneziaWG — `8443\udp`\
+  Порт для клиентов telemt — `443\tcp`
+
+---
+
+## Шаг 1. Настройка туннеля AmneziaWG (A <-> B)
+
+На всех серверах необходимо установить [amneziawg](https://github.com/amnezia-vpn/amneziawg-linux-kernel-module).\
+Далее все команды даны для **Ununtu 24.04**.\
+Для RHEL-based дистрибутивов инструкция по установке есть по ссылке выше.
+
+### Установка AmneziaWG (Сервера A и B)
+На каждом из серверов необходимо выполнить следующие шаги:
+
+#### 1. Добавление репозитория AmneziaWG и установка необходимых пакетов:
+```bash
+sudo apt install -y software-properties-common python3-launchpadlib gnupg2 linux-headers-$(uname -r) && \
+sudo add-apt-repository ppa:amnezia/ppa && \
+sudo apt-get install -y amneziawg
+```
+ 
+#### 2. Генерация уникальной пары ключей:
+```bash
+cd /etc/amnezia/amneziawg && \
+awg genkey | tee private.key | awg pubkey > public.key
+```
+В результате вы получите в папке `/etc/amnezia/amneziawg` два файла:\
+`private.key` - приватный и\
+`public.key` - публичный ключи сервера
+
+#### 3. Настройка сетевых интерфейсов:
+
+Параметры обфускации `S1`, `S2`, `H1`, `H2`, `H3`, `H4` должны быть строго идентичными на обоих серверах.\
+Параметры `Jc`, `Jmin` и `Jmax` могут отличатся.\
+Параметры `I1-I5` ([Custom Protocol Signature](https://docs.amnezia.org/documentation/amnezia-wg/)) нужно указывать на стороне _клиента_ (Сервер **А**).
+
+Рекомендации по выбору значений:
+```text
+Jc — 1 ≤ Jc ≤ 128; от 4 до 12 включительно
+Jmin — Jmax > Jmin < 1280*; рекомендовано 8
+Jmax — Jmin < Jmax ≤ 1280*; рекомендовано 80
+S1 — S1 ≤ 1132* (1280* - 148 = 1132); S1 + 56 ≠ S2;
+рекомендованный диапазон от 15 до 150 включительно
+S2 — S2 ≤ 1188* (1280* - 92 = 1188);
+рекомендованный диапазон от 15 до 150 включительно
+H1/H2/H3/H4 — должны быть уникальны и отличаться друг от друга;
+рекомендованный диапазон от 5 до 2147483647 включительно
+
+* Предполагается, что подключение к Интернету имеет MTU 1280.
+```
+> [!IMPORTANT]
+> Рекомендуется использовать собственные, уникальные значения.\
+> Для выбора параметров можете воспользоваться [генератором](https://htmlpreview.github.io/?https://gist.githubusercontent.com/avbor/955782b5c37b06240b243aa375baeac5/raw/13f5517ca473b47c412b9a99407066de973732bd/awg-gen.html).
+
+#### Конфигурация Сервера B (_Нидерланды_):
+
+Создаем файл конфигурации интерфейса (`awg0`)
+```bash
+nano /etc/amnezia/amneziawg/awg0.conf
+```
+
+Содержимое файла
+```ini
+[Interface]
+Address = 10.10.10.1/24
+ListenPort = 8443
+PrivateKey = <PRIVATE_KEY_SERVER_B>
+SaveConfig = true
+Jc = 4
+Jmin = 8
+Jmax = 80
+S1 = 29
+S2 = 15
+S3 = 18
+S4 = 0
+H1 = 2087563914
+H2 = 188817757
+H3 = 101784570
+H4 = 432174303
+
+[Peer]
+PublicKey = <PUBLIC_KEY_SERVER_A>
+AllowedIPs = 10.10.10.2/32
+```
+
+`ListenPort` - порт, на котором сервер будет ждать подключения, можете выбрать любой свободный.\
+`<PRIVATE_KEY_SERVER_B>` - содержимое файла `private.key` с сервера **B**.\
+`<PUBLIC_KEY_SERVER_A>` - содержимое файла `public.key` с сервера **A**.
+
+Открываем порт на фаерволе (если включен):
+```bash
+sudo ufw allow from <PUBLIC_IP_SERVER_A> to any port 8443 proto udp
+```
+
+`<PUBLIC_IP_SERVER_A>` - внешний IP адрес Сервера **A**.
+
+#### Конфигурация Сервера A (_РФ_):
+
+Создаем файл конфигурации интерфейса (`awg0`)
+```bash
+nano /etc/amnezia/amneziawg/awg0.conf
+```
+
+Содержимое файла
+```ini
+[Interface]
+Address = 10.10.10.2/24
+PrivateKey = <PRIVATE_KEY_SERVER_A>
+Jc = 4
+Jmin = 8
+Jmax = 80
+S1 = 29
+S2 = 15
+S3 = 18
+S4 = 0
+H1 = 2087563914
+H2 = 188817757
+H3 = 101784570
+H4 = 432174303
+I1 = <b 0xc10000000108981eba846e21f74e00>
+I2 = <b 0xc20000000108981eba846e21f74e00>
+I3 = <b 0xc30000000108981eba846e21f74e00>
+I4 = <b 0x43981eba846e21f74e>
+I5 = <b 0x43981eba846e21f74e>
+
+[Peer]
+PublicKey = <PUBLIC_KEY_SERVER_B>
+Endpoint = <PUBLIC_IP_SERVER_B>:8443
+AllowedIPs = 10.10.10.1/32
+PersistentKeepalive = 25
+```
+
+`<PRIVATE_KEY_SERVER_A>` - содержимое файла `private.key` с сервера **A**.\
+`<PUBLIC_KEY_SERVER_B>` - содержимое файла `public.key` с сервера **B**.\
+`<PUBLIC_IP_SERVER_B>` - публичный IP адресс сервера **B**.
+
+#### Включаем туннель на обоих серверах:
+```bash
+sudo systemctl enable --now awg-quick@awg0 
+```
+
+Убедитесь, что с Сервера `A` доступен Сервер `B` через туннель.
+```bash
+ping 10.10.10.1
+PING 10.10.10.1 (10.10.10.1) 56(84) bytes of data.
+64 bytes from 10.10.10.1: icmp_seq=1 ttl=64 time=35.1 ms
+64 bytes from 10.10.10.1: icmp_seq=2 ttl=64 time=35.0 ms
+64 bytes from 10.10.10.1: icmp_seq=3 ttl=64 time=35.1 ms
+^C
+
+```
+
+---
+
+## Шаг 2. Установка telemt на Сервере B (_условно Нидерланды_)
+
+Установка и настройка описаны [здесь](https://github.com/telemt/telemt/blob/main/docs/QUICK_START_GUIDE.ru.md) или [здесь](https://gitlab.com/An0nX/telemt-docker#-quick-start-docker-compose).\
+Подразумевается что telemt ожидает подключения на порту `443\tcp`.
+
+В конфиге telemt необходимо включить протокол `Proxy` и ограничить подключения к нему только через туннель.
+
+```toml
+[server]
+port = 443
+listen_addr_ipv4 = "10.10.10.1"
+proxy_protocol = true
+```
+
+А также, для правильной генерации ссылок, указать FQDN или IP адрес и порт Сервера `A` 
+
+```toml
+[general.links]
+show = "*"
+public_host = "<FQDN_OR_IP_SERVER_A>"
+public_port = 443
+```
+
+Открываем порт на фаерволе (если включен):
+```bash
+sudo ufw allow from 10.10.10.2 to any port 443 proto tcp
+```
+
+---
+
+### Шаг 3. Настройка HAProxy на Сервере A (_РФ_)
+
+Т.к. в стандартном репозитории Ubuntu версия относительно старая, имеет смысл воспользоваться официальным образом Docker.\
+[Инструкция](https://docs.docker.com/engine/install/ubuntu/) по установке Docker на Ubuntu.
+
+> [!WARNING]
+> По умолчанию у обычных пользователей нет прав на использование портов < 1024.\
+> Попытки запустить HAProxy на 443 порту могут приводить к ошибкам:
+> ```
+> [ALERT] (8) : Binding [/usr/local/etc/haproxy/haproxy.cfg:17] for frontend tcp_in_443: 
+> protocol tcpv4: cannot bind socket (Permission denied) for [0.0.0.0:443].
+> ```
+> Есть два простых способа обойти это ограничение, выберите что-то одно:
+> 1. На уровне ОС изменить настройку net.ipv4.ip_unprivileged_port_start, разрешив пользователям использовать все порты:
+> ```
+> echo "net.ipv4.ip_unprivileged_port_start = 0" | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
+> ```
+> или
+> 
+> 2. Запустить HAProxy под root:\
+> Раскомментируйте в docker-compose.yaml параметр `user: "root"`.
+
+#### Создаем папку для HAProxy:
+```bash
+mkdir -p /opt/docker-compose/haproxy && cd $_
+```
+#### Создаем файл docker-compose.yaml
+
+`nano docker-compose.yaml`
+
+Содержимое файла
+```yaml
+services:
+  haproxy:
+    image: haproxy:latest
+    container_name: haproxy
+    restart: unless-stopped
+    # user: "root"
+    network_mode: "host"
+    volumes:
+      - ./haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg:ro
+    logging:
+      driver: "json-file"
+      options:
+        max-size: "1m"
+        max-file: "1"
+```
+#### Создаем файл конфига haproxy.cfg
+Принимаем подключения на порту 443\tcp и отправляем их через туннель на Сервер `B` 10.10.10.1:443
+
+`nano haproxy.cfg`
+
+Содержимое файла
+```haproxy
+global
+    log stdout format raw local0
+    maxconn 10000
+
+defaults
+    log     global
+    mode    tcp
+    option  tcplog
+    option  clitcpka
+    option  srvtcpka
+    timeout connect 5s
+    timeout client  2h
+    timeout server  2h
+    timeout check   5s
+
+frontend tcp_in_443
+    bind *:443
+    maxconn 8000
+    option tcp-smart-accept
+    default_backend telemt_nodes
+
+backend telemt_nodes
+    option tcp-smart-connect
+    server server_a 10.10.10.1:443 check inter 5s rise 2 fall 3 send-proxy-v2
+
+
+```
+>[!WARNING]
+>**Файл должен заканчиваться пустой строкой, иначе HAProxy не запустится!**
+
+#### Разрешаем порт 443\tcp в фаерволе (если включен)
+```bash
+sudo ufw allow 443/tcp
+```
+
+#### Запускаем контейнер HAProxy
+```bash
+docker compose up -d
+```
+
+Если все настроено верно, то теперь можно пробовать подключить клиентов Telegram с использованием ссылок из лога\api telemt.

src/api/http_utils.rs

@@ -24,10 +24,7 @@ pub(super) fn success_response<T: Serialize>(
         .unwrap()
 }
 
-pub(super) fn error_response(
-    request_id: u64,
-    failure: ApiFailure,
-) -> hyper::Response<Full<Bytes>> {
+pub(super) fn error_response(request_id: u64, failure: ApiFailure) -> hyper::Response<Full<Bytes>> {
     let payload = ErrorResponse {
         ok: false,
         error: ErrorBody {

src/api/mod.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::too_many_arguments)]
+
 use std::convert::Infallible;
 use std::net::{IpAddr, SocketAddr};
 use std::path::PathBuf;
@@ -19,8 +21,8 @@ use crate::ip_tracker::UserIpTracker;
 use crate::proxy::route_mode::RouteRuntimeController;
 use crate::startup::StartupTracker;
 use crate::stats::Stats;
-use crate::transport::middle_proxy::MePool;
 use crate::transport::UpstreamManager;
+use crate::transport::middle_proxy::MePool;
 
 mod config_store;
 mod events;
@@ -36,8 +38,8 @@ mod runtime_zero;
 mod users;
 
 use config_store::{current_revision, parse_if_match};
-use http_utils::{error_response, read_json, read_optional_json, success_response};
 use events::ApiEventStore;
+use http_utils::{error_response, read_json, read_optional_json, success_response};
 use model::{
     ApiFailure, CreateUserRequest, HealthData, PatchUserRequest, RotateSecretRequest, SummaryData,
 };
@@ -55,11 +57,11 @@ use runtime_stats::{
     MinimalCacheEntry, build_dcs_data, build_me_writers_data, build_minimal_all_data,
     build_upstreams_data, build_zero_all_data,
 };
+use runtime_watch::spawn_runtime_watchers;
 use runtime_zero::{
     build_limits_effective_data, build_runtime_gates_data, build_security_posture_data,
     build_system_info_data,
 };
-use runtime_watch::spawn_runtime_watchers;
 use users::{create_user, delete_user, patch_user, rotate_secret, users_from_config};
 
 pub(super) struct ApiRuntimeState {
@@ -208,15 +210,15 @@ async fn handle(
         ));
     }
 
-    if !api_cfg.whitelist.is_empty()
-        && !api_cfg
-            .whitelist
-            .iter()
-            .any(|net| net.contains(peer.ip()))
+    if !api_cfg.whitelist.is_empty() && !api_cfg.whitelist.iter().any(|net| net.contains(peer.ip()))
     {
         return Ok(error_response(
             request_id,
-            ApiFailure::new(StatusCode::FORBIDDEN, "forbidden", "Source IP is not allowed"),
+            ApiFailure::new(
+                StatusCode::FORBIDDEN,
+                "forbidden",
+                "Source IP is not allowed",
+            ),
         ));
     }
 
@@ -347,7 +349,8 @@ async fn handle(
             }
             ("GET", "/v1/runtime/connections/summary") => {
                 let revision = current_revision(&shared.config_path).await?;
-                let data = build_runtime_connections_summary_data(shared.as_ref(), cfg.as_ref()).await;
+                let data =
+                    build_runtime_connections_summary_data(shared.as_ref(), cfg.as_ref()).await;
                 Ok(success_response(StatusCode::OK, data, revision))
             }
             ("GET", "/v1/runtime/events/recent") => {
@@ -389,13 +392,16 @@ async fn handle(
                 let (data, revision) = match result {
                     Ok(ok) => ok,
                     Err(error) => {
-                        shared.runtime_events.record("api.user.create.failed", error.code);
+                        shared
+                            .runtime_events
+                            .record("api.user.create.failed", error.code);
                         return Err(error);
                     }
                 };
-                shared
-                    .runtime_events
-                    .record("api.user.create.ok", format!("username={}", data.user.username));
+                shared.runtime_events.record(
+                    "api.user.create.ok",
+                    format!("username={}", data.user.username),
+                );
                 Ok(success_response(StatusCode::CREATED, data, revision))
             }
             _ => {
@@ -414,7 +420,8 @@ async fn handle(
                             detected_ip_v6,
                         )
                         .await;
-                        if let Some(user_info) = users.into_iter().find(|entry| entry.username == user)
+                        if let Some(user_info) =
+                            users.into_iter().find(|entry| entry.username == user)
                         {
                             return Ok(success_response(StatusCode::OK, user_info, revision));
                         }
@@ -435,7 +442,8 @@ async fn handle(
                             ));
                         }
                         let expected_revision = parse_if_match(req.headers());
-                        let body = read_json::<PatchUserRequest>(req.into_body(), body_limit).await?;
+                        let body =
+                            read_json::<PatchUserRequest>(req.into_body(), body_limit).await?;
                         let result = patch_user(user, body, expected_revision, &shared).await;
                         let (data, revision) = match result {
                             Ok(ok) => ok,
@@ -475,10 +483,9 @@ async fn handle(
                                 return Err(error);
                             }
                         };
-                        shared.runtime_events.record(
-                            "api.user.delete.ok",
-                            format!("username={}", deleted_user),
-                        );
+                        shared
+                            .runtime_events
+                            .record("api.user.delete.ok", format!("username={}", deleted_user));
                         return Ok(success_response(StatusCode::OK, deleted_user, revision));
                     }
                     if method == Method::POST

src/api/model.rs

@@ -1,10 +1,12 @@
 use std::net::IpAddr;
+use std::sync::OnceLock;
 
 use chrono::{DateTime, Utc};
 use hyper::StatusCode;
-use rand::Rng;
 use serde::{Deserialize, Serialize};
 
+use crate::crypto::SecureRandom;
+
 const MAX_USERNAME_LEN: usize = 64;
 
 #[derive(Debug)]
@@ -172,6 +174,24 @@ pub(super) struct ZeroMiddleProxyData {
     pub(super) route_drop_queue_full_total: u64,
     pub(super) route_drop_queue_full_base_total: u64,
     pub(super) route_drop_queue_full_high_total: u64,
+    pub(super) d2c_batches_total: u64,
+    pub(super) d2c_batch_frames_total: u64,
+    pub(super) d2c_batch_bytes_total: u64,
+    pub(super) d2c_flush_reason_queue_drain_total: u64,
+    pub(super) d2c_flush_reason_batch_frames_total: u64,
+    pub(super) d2c_flush_reason_batch_bytes_total: u64,
+    pub(super) d2c_flush_reason_max_delay_total: u64,
+    pub(super) d2c_flush_reason_ack_immediate_total: u64,
+    pub(super) d2c_flush_reason_close_total: u64,
+    pub(super) d2c_data_frames_total: u64,
+    pub(super) d2c_ack_frames_total: u64,
+    pub(super) d2c_payload_bytes_total: u64,
+    pub(super) d2c_write_mode_coalesced_total: u64,
+    pub(super) d2c_write_mode_split_total: u64,
+    pub(super) d2c_quota_reject_pre_write_total: u64,
+    pub(super) d2c_quota_reject_post_write_total: u64,
+    pub(super) d2c_frame_buf_shrink_total: u64,
+    pub(super) d2c_frame_buf_shrink_bytes_total: u64,
     pub(super) socks_kdf_strict_reject_total: u64,
     pub(super) socks_kdf_compat_fallback_total: u64,
     pub(super) endpoint_quarantine_total: u64,
@@ -196,8 +216,6 @@ pub(super) struct ZeroPoolData {
     pub(super) pool_swap_total: u64,
     pub(super) pool_drain_active: u64,
     pub(super) pool_force_close_total: u64,
-    pub(super) pool_drain_soft_evict_total: u64,
-    pub(super) pool_drain_soft_evict_writer_total: u64,
     pub(super) pool_stale_pick_total: u64,
     pub(super) writer_removed_total: u64,
     pub(super) writer_removed_unexpected_total: u64,
@@ -206,16 +224,6 @@ pub(super) struct ZeroPoolData {
     pub(super) refill_failed_total: u64,
     pub(super) writer_restored_same_endpoint_total: u64,
     pub(super) writer_restored_fallback_total: u64,
-    pub(super) teardown_attempt_total_normal: u64,
-    pub(super) teardown_attempt_total_hard_detach: u64,
-    pub(super) teardown_success_total_normal: u64,
-    pub(super) teardown_success_total_hard_detach: u64,
-    pub(super) teardown_timeout_total: u64,
-    pub(super) teardown_escalation_total: u64,
-    pub(super) teardown_noop_total: u64,
-    pub(super) teardown_cleanup_side_effect_failures_total: u64,
-    pub(super) teardown_duration_count_total: u64,
-    pub(super) teardown_duration_sum_seconds_total: f64,
 }
 
 #[derive(Serialize, Clone)]
@@ -248,7 +256,6 @@ pub(super) struct MeWritersSummary {
     pub(super) available_pct: f64,
     pub(super) required_writers: usize,
     pub(super) alive_writers: usize,
-    pub(super) coverage_ratio: f64,
     pub(super) coverage_pct: f64,
     pub(super) fresh_alive_writers: usize,
     pub(super) fresh_coverage_pct: f64,
@@ -297,7 +304,6 @@ pub(super) struct DcStatus {
     pub(super) floor_max: usize,
     pub(super) floor_capped: bool,
     pub(super) alive_writers: usize,
-    pub(super) coverage_ratio: f64,
     pub(super) coverage_pct: f64,
     pub(super) fresh_alive_writers: usize,
     pub(super) fresh_coverage_pct: f64,
@@ -375,12 +381,6 @@ pub(super) struct MinimalMeRuntimeData {
     pub(super) me_reconnect_backoff_cap_ms: u64,
     pub(super) me_reconnect_fast_retry_count: u32,
     pub(super) me_pool_drain_ttl_secs: u64,
-    pub(super) me_instadrain: bool,
-    pub(super) me_pool_drain_soft_evict_enabled: bool,
-    pub(super) me_pool_drain_soft_evict_grace_secs: u64,
-    pub(super) me_pool_drain_soft_evict_per_writer: u8,
-    pub(super) me_pool_drain_soft_evict_budget_per_core: u16,
-    pub(super) me_pool_drain_soft_evict_cooldown_ms: u64,
     pub(super) me_pool_force_close_secs: u64,
     pub(super) me_pool_min_fresh_ratio: f32,
     pub(super) me_bind_stale_mode: &'static str,
@@ -502,7 +502,9 @@ pub(super) fn is_valid_username(user: &str) -> bool {
 }
 
 pub(super) fn random_user_secret() -> String {
+    static API_SECRET_RNG: OnceLock<SecureRandom> = OnceLock::new();
+    let rng = API_SECRET_RNG.get_or_init(SecureRandom::new);
     let mut bytes = [0u8; 16];
-    rand::rng().fill(&mut bytes);
+    rng.fill(&mut bytes);
     hex::encode(bytes)
 }

src/api/runtime_init.rs

@@ -167,11 +167,7 @@ async fn current_me_pool_stage_progress(shared: &ApiShared) -> Option<f64> {
     let pool = shared.me_pool.read().await.clone()?;
     let status = pool.api_status_snapshot().await;
     let configured_dc_groups = status.configured_dc_groups;
-    let covered_dc_groups = status
-        .dcs
-        .iter()
-        .filter(|dc| dc.alive_writers > 0)
-        .count();
+    let covered_dc_groups = status.dcs.iter().filter(|dc| dc.alive_writers > 0).count();
 
     let dc_coverage = ratio_01(covered_dc_groups, configured_dc_groups);
     let writer_coverage = ratio_01(status.alive_writers, status.required_writers);

src/api/runtime_min.rs

@@ -4,9 +4,6 @@ use std::time::{SystemTime, UNIX_EPOCH};
 use serde::Serialize;
 
 use crate::config::ProxyConfig;
-use crate::stats::{
-    MeWriterCleanupSideEffectStep, MeWriterTeardownMode, MeWriterTeardownReason, Stats,
-};
 
 use super::ApiShared;
 
@@ -101,50 +98,6 @@ pub(super) struct RuntimeMeQualityCountersData {
     pub(super) reconnect_success_total: u64,
 }
 
-#[derive(Serialize)]
-pub(super) struct RuntimeMeQualityTeardownAttemptData {
-    pub(super) reason: &'static str,
-    pub(super) mode: &'static str,
-    pub(super) total: u64,
-}
-
-#[derive(Serialize)]
-pub(super) struct RuntimeMeQualityTeardownSuccessData {
-    pub(super) mode: &'static str,
-    pub(super) total: u64,
-}
-
-#[derive(Serialize)]
-pub(super) struct RuntimeMeQualityTeardownSideEffectData {
-    pub(super) step: &'static str,
-    pub(super) total: u64,
-}
-
-#[derive(Serialize)]
-pub(super) struct RuntimeMeQualityTeardownDurationBucketData {
-    pub(super) le_seconds: &'static str,
-    pub(super) total: u64,
-}
-
-#[derive(Serialize)]
-pub(super) struct RuntimeMeQualityTeardownDurationData {
-    pub(super) mode: &'static str,
-    pub(super) count: u64,
-    pub(super) sum_seconds: f64,
-    pub(super) buckets: Vec<RuntimeMeQualityTeardownDurationBucketData>,
-}
-
-#[derive(Serialize)]
-pub(super) struct RuntimeMeQualityTeardownData {
-    pub(super) attempts: Vec<RuntimeMeQualityTeardownAttemptData>,
-    pub(super) success: Vec<RuntimeMeQualityTeardownSuccessData>,
-    pub(super) timeout_total: u64,
-    pub(super) escalation_total: u64,
-    pub(super) noop_total: u64,
-    pub(super) cleanup_side_effect_failures: Vec<RuntimeMeQualityTeardownSideEffectData>,
-    pub(super) duration: Vec<RuntimeMeQualityTeardownDurationData>,
-}
-
 #[derive(Serialize)]
 pub(super) struct RuntimeMeQualityRouteDropData {
     pub(super) no_conn_total: u64,
@@ -179,14 +132,12 @@ pub(super) struct RuntimeMeQualityDcRttData {
     pub(super) rtt_ema_ms: Option<f64>,
     pub(super) alive_writers: usize,
     pub(super) required_writers: usize,
-    pub(super) coverage_ratio: f64,
     pub(super) coverage_pct: f64,
 }
 
 #[derive(Serialize)]
 pub(super) struct RuntimeMeQualityPayload {
     pub(super) counters: RuntimeMeQualityCountersData,
-    pub(super) teardown: RuntimeMeQualityTeardownData,
     pub(super) route_drops: RuntimeMeQualityRouteDropData,
     pub(super) family_states: Vec<RuntimeMeQualityFamilyStateData>,
     pub(super) drain_gate: RuntimeMeQualityDrainGateData,
@@ -457,7 +408,6 @@ pub(super) async fn build_runtime_me_quality_data(shared: &ApiShared) -> Runtime
                 reconnect_attempt_total: shared.stats.get_me_reconnect_attempts(),
                 reconnect_success_total: shared.stats.get_me_reconnect_success(),
             },
-            teardown: build_runtime_me_teardown_data(shared),
             route_drops: RuntimeMeQualityRouteDropData {
                 no_conn_total: shared.stats.get_me_route_drop_no_conn(),
                 channel_closed_total: shared.stats.get_me_route_drop_channel_closed(),
@@ -480,7 +430,6 @@ pub(super) async fn build_runtime_me_quality_data(shared: &ApiShared) -> Runtime
                     rtt_ema_ms: dc.rtt_ms,
                     alive_writers: dc.alive_writers,
                     required_writers: dc.required_writers,
-                    coverage_ratio: dc.coverage_ratio,
                     coverage_pct: dc.coverage_pct,
                 })
                 .collect(),
@@ -488,81 +437,6 @@ pub(super) async fn build_runtime_me_quality_data(shared: &ApiShared) -> Runtime
     }
 }
 
-fn build_runtime_me_teardown_data(shared: &ApiShared) -> RuntimeMeQualityTeardownData {
-    let attempts = MeWriterTeardownReason::ALL
-        .iter()
-        .copied()
-        .flat_map(|reason| {
-            MeWriterTeardownMode::ALL
-                .iter()
-                .copied()
-                .map(move |mode| RuntimeMeQualityTeardownAttemptData {
-                    reason: reason.as_str(),
-                    mode: mode.as_str(),
-                    total: shared.stats.get_me_writer_teardown_attempt_total(reason, mode),
-                })
-        })
-        .collect();
-
-    let success = MeWriterTeardownMode::ALL
-        .iter()
-        .copied()
-        .map(|mode| RuntimeMeQualityTeardownSuccessData {
-            mode: mode.as_str(),
-            total: shared.stats.get_me_writer_teardown_success_total(mode),
-        })
-        .collect();
-
-    let cleanup_side_effect_failures = MeWriterCleanupSideEffectStep::ALL
-        .iter()
-        .copied()
-        .map(|step| RuntimeMeQualityTeardownSideEffectData {
-            step: step.as_str(),
-            total: shared
-                .stats
-                .get_me_writer_cleanup_side_effect_failures_total(step),
-        })
-        .collect();
-
-    let duration = MeWriterTeardownMode::ALL
-        .iter()
-        .copied()
-        .map(|mode| {
-            let count = shared.stats.get_me_writer_teardown_duration_count(mode);
-            let mut buckets: Vec<RuntimeMeQualityTeardownDurationBucketData> = Stats::me_writer_teardown_duration_bucket_labels()
-                .iter()
-                .enumerate()
-                .map(|(bucket_idx, label)| RuntimeMeQualityTeardownDurationBucketData {
-                    le_seconds: label,
-                    total: shared
-                        .stats
-                        .get_me_writer_teardown_duration_bucket_total(mode, bucket_idx),
-                })
-                .collect();
-            buckets.push(RuntimeMeQualityTeardownDurationBucketData {
-                le_seconds: "+Inf",
-                total: count,
-            });
-            RuntimeMeQualityTeardownDurationData {
-                mode: mode.as_str(),
-                count,
-                sum_seconds: shared.stats.get_me_writer_teardown_duration_sum_seconds(mode),
-                buckets,
-            }
-        })
-        .collect();
-
-    RuntimeMeQualityTeardownData {
-        attempts,
-        success,
-        timeout_total: shared.stats.get_me_writer_teardown_timeout_total(),
-        escalation_total: shared.stats.get_me_writer_teardown_escalation_total(),
-        noop_total: shared.stats.get_me_writer_teardown_noop_total(),
-        cleanup_side_effect_failures,
-        duration,
-    }
-}
-
 pub(super) async fn build_runtime_upstream_quality_data(
     shared: &ApiShared,
 ) -> RuntimeUpstreamQualityData {

src/api/runtime_stats.rs

@@ -1,9 +1,9 @@
 use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 
 use crate::config::ApiConfig;
-use crate::stats::{MeWriterTeardownMode, Stats};
-use crate::transport::upstream::IpPreference;
+use crate::stats::Stats;
 use crate::transport::UpstreamRouteKind;
+use crate::transport::upstream::IpPreference;
 
 use super::ApiShared;
 use super::model::{
@@ -68,6 +68,25 @@ pub(super) fn build_zero_all_data(stats: &Stats, configured_users: usize) -> Zer
             route_drop_queue_full_total: stats.get_me_route_drop_queue_full(),
             route_drop_queue_full_base_total: stats.get_me_route_drop_queue_full_base(),
             route_drop_queue_full_high_total: stats.get_me_route_drop_queue_full_high(),
+            d2c_batches_total: stats.get_me_d2c_batches_total(),
+            d2c_batch_frames_total: stats.get_me_d2c_batch_frames_total(),
+            d2c_batch_bytes_total: stats.get_me_d2c_batch_bytes_total(),
+            d2c_flush_reason_queue_drain_total: stats.get_me_d2c_flush_reason_queue_drain_total(),
+            d2c_flush_reason_batch_frames_total: stats.get_me_d2c_flush_reason_batch_frames_total(),
+            d2c_flush_reason_batch_bytes_total: stats.get_me_d2c_flush_reason_batch_bytes_total(),
+            d2c_flush_reason_max_delay_total: stats.get_me_d2c_flush_reason_max_delay_total(),
+            d2c_flush_reason_ack_immediate_total: stats
+                .get_me_d2c_flush_reason_ack_immediate_total(),
+            d2c_flush_reason_close_total: stats.get_me_d2c_flush_reason_close_total(),
+            d2c_data_frames_total: stats.get_me_d2c_data_frames_total(),
+            d2c_ack_frames_total: stats.get_me_d2c_ack_frames_total(),
+            d2c_payload_bytes_total: stats.get_me_d2c_payload_bytes_total(),
+            d2c_write_mode_coalesced_total: stats.get_me_d2c_write_mode_coalesced_total(),
+            d2c_write_mode_split_total: stats.get_me_d2c_write_mode_split_total(),
+            d2c_quota_reject_pre_write_total: stats.get_me_d2c_quota_reject_pre_write_total(),
+            d2c_quota_reject_post_write_total: stats.get_me_d2c_quota_reject_post_write_total(),
+            d2c_frame_buf_shrink_total: stats.get_me_d2c_frame_buf_shrink_total(),
+            d2c_frame_buf_shrink_bytes_total: stats.get_me_d2c_frame_buf_shrink_bytes_total(),
             socks_kdf_strict_reject_total: stats.get_me_socks_kdf_strict_reject(),
             socks_kdf_compat_fallback_total: stats.get_me_socks_kdf_compat_fallback(),
             endpoint_quarantine_total: stats.get_me_endpoint_quarantine_total(),
@@ -96,8 +115,6 @@ pub(super) fn build_zero_all_data(stats: &Stats, configured_users: usize) -> Zer
             pool_swap_total: stats.get_pool_swap_total(),
             pool_drain_active: stats.get_pool_drain_active(),
             pool_force_close_total: stats.get_pool_force_close_total(),
-            pool_drain_soft_evict_total: stats.get_pool_drain_soft_evict_total(),
-            pool_drain_soft_evict_writer_total: stats.get_pool_drain_soft_evict_writer_total(),
             pool_stale_pick_total: stats.get_pool_stale_pick_total(),
             writer_removed_total: stats.get_me_writer_removed_total(),
             writer_removed_unexpected_total: stats.get_me_writer_removed_unexpected_total(),
@@ -106,29 +123,6 @@ pub(super) fn build_zero_all_data(stats: &Stats, configured_users: usize) -> Zer
             refill_failed_total: stats.get_me_refill_failed_total(),
             writer_restored_same_endpoint_total: stats.get_me_writer_restored_same_endpoint_total(),
             writer_restored_fallback_total: stats.get_me_writer_restored_fallback_total(),
-            teardown_attempt_total_normal: stats
-                .get_me_writer_teardown_attempt_total_by_mode(MeWriterTeardownMode::Normal),
-            teardown_attempt_total_hard_detach: stats
-                .get_me_writer_teardown_attempt_total_by_mode(MeWriterTeardownMode::HardDetach),
-            teardown_success_total_normal: stats
-                .get_me_writer_teardown_success_total(MeWriterTeardownMode::Normal),
-            teardown_success_total_hard_detach: stats
-                .get_me_writer_teardown_success_total(MeWriterTeardownMode::HardDetach),
-            teardown_timeout_total: stats.get_me_writer_teardown_timeout_total(),
-            teardown_escalation_total: stats.get_me_writer_teardown_escalation_total(),
-            teardown_noop_total: stats.get_me_writer_teardown_noop_total(),
-            teardown_cleanup_side_effect_failures_total: stats
-                .get_me_writer_cleanup_side_effect_failures_total_all(),
-            teardown_duration_count_total: stats
-                .get_me_writer_teardown_duration_count(MeWriterTeardownMode::Normal)
-                .saturating_add(
-                    stats.get_me_writer_teardown_duration_count(MeWriterTeardownMode::HardDetach),
-                ),
-            teardown_duration_sum_seconds_total: stats
-                .get_me_writer_teardown_duration_sum_seconds(MeWriterTeardownMode::Normal)
-                + stats.get_me_writer_teardown_duration_sum_seconds(
-                    MeWriterTeardownMode::HardDetach,
-                ),
         },
         desync: ZeroDesyncData {
             secure_padding_invalid_total: stats.get_secure_padding_invalid(),
@@ -340,7 +334,6 @@ async fn get_minimal_payload_cached(
             available_pct: status.available_pct,
             required_writers: status.required_writers,
             alive_writers: status.alive_writers,
-            coverage_ratio: status.coverage_ratio,
             coverage_pct: status.coverage_pct,
             fresh_alive_writers: status.fresh_alive_writers,
             fresh_coverage_pct: status.fresh_coverage_pct,
@@ -398,7 +391,6 @@ async fn get_minimal_payload_cached(
                 floor_max: entry.floor_max,
                 floor_capped: entry.floor_capped,
                 alive_writers: entry.alive_writers,
-                coverage_ratio: entry.coverage_ratio,
                 coverage_pct: entry.coverage_pct,
                 fresh_alive_writers: entry.fresh_alive_writers,
                 fresh_coverage_pct: entry.fresh_coverage_pct,
@@ -452,12 +444,6 @@ async fn get_minimal_payload_cached(
         me_reconnect_backoff_cap_ms: runtime.me_reconnect_backoff_cap_ms,
         me_reconnect_fast_retry_count: runtime.me_reconnect_fast_retry_count,
         me_pool_drain_ttl_secs: runtime.me_pool_drain_ttl_secs,
-        me_instadrain: runtime.me_instadrain,
-        me_pool_drain_soft_evict_enabled: runtime.me_pool_drain_soft_evict_enabled,
-        me_pool_drain_soft_evict_grace_secs: runtime.me_pool_drain_soft_evict_grace_secs,
-        me_pool_drain_soft_evict_per_writer: runtime.me_pool_drain_soft_evict_per_writer,
-        me_pool_drain_soft_evict_budget_per_core: runtime.me_pool_drain_soft_evict_budget_per_core,
-        me_pool_drain_soft_evict_cooldown_ms: runtime.me_pool_drain_soft_evict_cooldown_ms,
         me_pool_force_close_secs: runtime.me_pool_force_close_secs,
         me_pool_min_fresh_ratio: runtime.me_pool_min_fresh_ratio,
         me_bind_stale_mode: runtime.me_bind_stale_mode,
@@ -526,7 +512,6 @@ fn disabled_me_writers(now_epoch_secs: u64, reason: &'static str) -> MeWritersDa
             available_pct: 0.0,
             required_writers: 0,
             alive_writers: 0,
-            coverage_ratio: 0.0,
             coverage_pct: 0.0,
             fresh_alive_writers: 0,
             fresh_coverage_pct: 0.0,

src/api/runtime_zero.rs

@@ -35,11 +35,14 @@ pub(super) struct RuntimeGatesData {
     pub(super) conditional_cast_enabled: bool,
     pub(super) me_runtime_ready: bool,
     pub(super) me2dc_fallback_enabled: bool,
+    pub(super) me2dc_fast_enabled: bool,
     pub(super) use_middle_proxy: bool,
     pub(super) route_mode: &'static str,
     pub(super) reroute_active: bool,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub(super) reroute_to_direct_at_epoch_secs: Option<u64>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) reroute_reason: Option<&'static str>,
     pub(super) startup_status: &'static str,
     pub(super) startup_stage: String,
     pub(super) startup_progress_pct: f64,
@@ -86,6 +89,7 @@ pub(super) struct EffectiveMiddleProxyLimits {
     pub(super) writer_pick_mode: &'static str,
     pub(super) writer_pick_sample_size: u8,
     pub(super) me2dc_fallback: bool,
+    pub(super) me2dc_fast: bool,
 }
 
 #[derive(Serialize)]
@@ -128,7 +132,8 @@ pub(super) fn build_system_info_data(
         .runtime_state
         .last_config_reload_epoch_secs
         .load(Ordering::Relaxed);
-    let last_config_reload_epoch_secs = (last_reload_epoch_secs > 0).then_some(last_reload_epoch_secs);
+    let last_config_reload_epoch_secs =
+        (last_reload_epoch_secs > 0).then_some(last_reload_epoch_secs);
 
     let git_commit = option_env!("TELEMT_GIT_COMMIT")
         .or(option_env!("VERGEN_GIT_SHA"))
@@ -153,7 +158,10 @@ pub(super) fn build_system_info_data(
         uptime_seconds: shared.stats.uptime_secs(),
         config_path: shared.config_path.display().to_string(),
         config_hash: revision.to_string(),
-        config_reload_count: shared.runtime_state.config_reload_count.load(Ordering::Relaxed),
+        config_reload_count: shared
+            .runtime_state
+            .config_reload_count
+            .load(Ordering::Relaxed),
         last_config_reload_epoch_secs,
     }
 }
@@ -165,6 +173,8 @@ pub(super) async fn build_runtime_gates_data(
     let startup_summary = build_runtime_startup_summary(shared).await;
     let route_state = shared.route_runtime.snapshot();
     let route_mode = route_state.mode.as_str();
+    let fast_fallback_enabled =
+        cfg.general.use_middle_proxy && cfg.general.me2dc_fallback && cfg.general.me2dc_fast;
     let reroute_active = cfg.general.use_middle_proxy
         && cfg.general.me2dc_fallback
         && matches!(route_state.mode, RelayRouteMode::Direct);
@@ -173,6 +183,15 @@ pub(super) async fn build_runtime_gates_data(
     } else {
         None
     };
+    let reroute_reason = if reroute_active {
+        if fast_fallback_enabled {
+            Some("fast_not_ready_fallback")
+        } else {
+            Some("strict_grace_fallback")
+        }
+    } else {
+        None
+    };
     let me_runtime_ready = if !cfg.general.use_middle_proxy {
         true
     } else {
@@ -190,10 +209,12 @@ pub(super) async fn build_runtime_gates_data(
         conditional_cast_enabled: cfg.general.use_middle_proxy,
         me_runtime_ready,
         me2dc_fallback_enabled: cfg.general.me2dc_fallback,
+        me2dc_fast_enabled: fast_fallback_enabled,
         use_middle_proxy: cfg.general.use_middle_proxy,
         route_mode,
         reroute_active,
         reroute_to_direct_at_epoch_secs,
+        reroute_reason,
         startup_status: startup_summary.status,
         startup_stage: startup_summary.stage,
         startup_progress_pct: startup_summary.progress_pct,
@@ -233,9 +254,7 @@ pub(super) fn build_limits_effective_data(cfg: &ProxyConfig) -> EffectiveLimitsD
             adaptive_floor_writers_per_core_total: cfg
                 .general
                 .me_adaptive_floor_writers_per_core_total,
-            adaptive_floor_cpu_cores_override: cfg
-                .general
-                .me_adaptive_floor_cpu_cores_override,
+            adaptive_floor_cpu_cores_override: cfg.general.me_adaptive_floor_cpu_cores_override,
             adaptive_floor_max_extra_writers_single_per_core: cfg
                 .general
                 .me_adaptive_floor_max_extra_writers_single_per_core,
@@ -261,6 +280,7 @@ pub(super) fn build_limits_effective_data(cfg: &ProxyConfig) -> EffectiveLimitsD
             writer_pick_mode: me_writer_pick_mode_label(cfg.general.me_writer_pick_mode),
             writer_pick_sample_size: cfg.general.me_writer_pick_sample_size,
             me2dc_fallback: cfg.general.me2dc_fallback,
+            me2dc_fast: cfg.general.me2dc_fast,
         },
         user_ip_policy: EffectiveUserIpPolicyLimits {
             global_each: cfg.access.user_max_unique_ips_global_each,

src/api/users.rs

@@ -46,7 +46,9 @@ pub(super) async fn create_user(
         None => random_user_secret(),
     };
 
-    if let Some(ad_tag) = body.user_ad_tag.as_ref() && !is_valid_ad_tag(ad_tag) {
+    if let Some(ad_tag) = body.user_ad_tag.as_ref()
+        && !is_valid_ad_tag(ad_tag)
+    {
         return Err(ApiFailure::bad_request(
             "user_ad_tag must be exactly 32 hex characters",
         ));
@@ -65,12 +67,18 @@ pub(super) async fn create_user(
         ));
     }
 
-    cfg.access.users.insert(body.username.clone(), secret.clone());
+    cfg.access
+        .users
+        .insert(body.username.clone(), secret.clone());
     if let Some(ad_tag) = body.user_ad_tag {
-        cfg.access.user_ad_tags.insert(body.username.clone(), ad_tag);
+        cfg.access
+            .user_ad_tags
+            .insert(body.username.clone(), ad_tag);
     }
     if let Some(limit) = body.max_tcp_conns {
-        cfg.access.user_max_tcp_conns.insert(body.username.clone(), limit);
+        cfg.access
+            .user_max_tcp_conns
+            .insert(body.username.clone(), limit);
     }
     if let Some(expiration) = expiration {
         cfg.access
@@ -78,7 +86,9 @@ pub(super) async fn create_user(
             .insert(body.username.clone(), expiration);
     }
     if let Some(quota) = body.data_quota_bytes {
-        cfg.access.user_data_quota.insert(body.username.clone(), quota);
+        cfg.access
+            .user_data_quota
+            .insert(body.username.clone(), quota);
     }
 
     let updated_limit = body.max_unique_ips;
@@ -108,11 +118,15 @@ pub(super) async fn create_user(
         touched_sections.push(AccessSection::UserMaxUniqueIps);
     }
 
-    let revision = save_access_sections_to_disk(&shared.config_path, &cfg, &touched_sections).await?;
+    let revision =
+        save_access_sections_to_disk(&shared.config_path, &cfg, &touched_sections).await?;
     drop(_guard);
 
     if let Some(limit) = updated_limit {
-        shared.ip_tracker.set_user_limit(&body.username, limit).await;
+        shared
+            .ip_tracker
+            .set_user_limit(&body.username, limit)
+            .await;
     }
     let (detected_ip_v4, detected_ip_v6) = shared.detected_link_ips();
 
@@ -140,12 +154,7 @@ pub(super) async fn create_user(
             recent_unique_ips: 0,
             recent_unique_ips_list: Vec::new(),
             total_octets: 0,
-            links: build_user_links(
-                &cfg,
-                &secret,
-                detected_ip_v4,
-                detected_ip_v6,
-            ),
+            links: build_user_links(&cfg, &secret, detected_ip_v4, detected_ip_v6),
         });
 
     Ok((CreateUserResponse { user, secret }, revision))
@@ -157,12 +166,16 @@ pub(super) async fn patch_user(
     expected_revision: Option<String>,
     shared: &ApiShared,
 ) -> Result<(UserInfo, String), ApiFailure> {
-    if let Some(secret) = body.secret.as_ref() && !is_valid_user_secret(secret) {
+    if let Some(secret) = body.secret.as_ref()
+        && !is_valid_user_secret(secret)
+    {
         return Err(ApiFailure::bad_request(
             "secret must be exactly 32 hex characters",
         ));
     }
-    if let Some(ad_tag) = body.user_ad_tag.as_ref() && !is_valid_ad_tag(ad_tag) {
+    if let Some(ad_tag) = body.user_ad_tag.as_ref()
+        && !is_valid_ad_tag(ad_tag)
+    {
         return Err(ApiFailure::bad_request(
             "user_ad_tag must be exactly 32 hex characters",
         ));
@@ -187,10 +200,14 @@ pub(super) async fn patch_user(
         cfg.access.user_ad_tags.insert(user.to_string(), ad_tag);
     }
     if let Some(limit) = body.max_tcp_conns {
-        cfg.access.user_max_tcp_conns.insert(user.to_string(), limit);
+        cfg.access
+            .user_max_tcp_conns
+            .insert(user.to_string(), limit);
     }
     if let Some(expiration) = expiration {
-        cfg.access.user_expirations.insert(user.to_string(), expiration);
+        cfg.access
+            .user_expirations
+            .insert(user.to_string(), expiration);
     }
     if let Some(quota) = body.data_quota_bytes {
         cfg.access.user_data_quota.insert(user.to_string(), quota);
@@ -198,7 +215,9 @@ pub(super) async fn patch_user(
 
     let mut updated_limit = None;
     if let Some(limit) = body.max_unique_ips {
-        cfg.access.user_max_unique_ips.insert(user.to_string(), limit);
+        cfg.access
+            .user_max_unique_ips
+            .insert(user.to_string(), limit);
         updated_limit = Some(limit);
     }
 
@@ -263,7 +282,8 @@ pub(super) async fn rotate_secret(
         AccessSection::UserDataQuota,
         AccessSection::UserMaxUniqueIps,
     ];
-    let revision = save_access_sections_to_disk(&shared.config_path, &cfg, &touched_sections).await?;
+    let revision =
+        save_access_sections_to_disk(&shared.config_path, &cfg, &touched_sections).await?;
     drop(_guard);
 
     let (detected_ip_v4, detected_ip_v6) = shared.detected_link_ips();
@@ -330,7 +350,8 @@ pub(super) async fn delete_user(
         AccessSection::UserDataQuota,
         AccessSection::UserMaxUniqueIps,
     ];
-    let revision = save_access_sections_to_disk(&shared.config_path, &cfg, &touched_sections).await?;
+    let revision =
+        save_access_sections_to_disk(&shared.config_path, &cfg, &touched_sections).await?;
     drop(_guard);
     shared.ip_tracker.remove_user_limit(user).await;
     shared.ip_tracker.clear_user_ips(user).await;
@@ -365,12 +386,7 @@ pub(super) async fn users_from_config(
             .users
             .get(&username)
             .map(|secret| {
-                build_user_links(
-                    cfg,
-                    secret,
-                    startup_detected_ip_v4,
-                    startup_detected_ip_v6,
-                )
+                build_user_links(cfg, secret, startup_detected_ip_v4, startup_detected_ip_v6)
             })
             .unwrap_or(UserLinks {
                 classic: Vec::new(),
@@ -392,10 +408,8 @@ pub(super) async fn users_from_config(
                 .get(&username)
                 .copied()
                 .filter(|limit| *limit > 0)
-                .or(
-                    (cfg.access.user_max_unique_ips_global_each > 0)
-                        .then_some(cfg.access.user_max_unique_ips_global_each),
-                ),
+                .or((cfg.access.user_max_unique_ips_global_each > 0)
+                    .then_some(cfg.access.user_max_unique_ips_global_each)),
             current_connections: stats.get_user_curr_connects(&username),
             active_unique_ips: active_ip_list.len(),
             active_unique_ips_list: active_ip_list,
@@ -481,12 +495,12 @@ fn resolve_link_hosts(
             push_unique_host(&mut hosts, host);
             continue;
         }
-        if let Some(ip) = listener.announce_ip {
-            if !ip.is_unspecified() {
+        if let Some(ip) = listener.announce_ip
+            && !ip.is_unspecified()
+        {
             push_unique_host(&mut hosts, &ip.to_string());
             continue;
         }
-        }
         if listener.ip.is_unspecified() {
             let detected_ip = if listener.ip.is_ipv4() {
                 startup_detected_ip_v4

src/cli.rs

@@ -1,9 +1,9 @@
 //! CLI commands: --init (fire-and-forget setup)
 
+use rand::RngExt;
 use std::fs;
 use std::path::{Path, PathBuf};
 use std::process::Command;
-use rand::Rng;
 
 /// Options for the init command
 pub struct InitOptions {
@@ -114,8 +114,8 @@ pub fn run_init(opts: InitOptions) -> Result<(), Box<dyn std::error::Error>> {
     eprintln!("[+] Config written to {}", config_path.display());
 
     // 4. Write systemd unit
-    let exe_path = std::env::current_exe()
-        .unwrap_or_else(|_| PathBuf::from("/usr/local/bin/telemt"));
+    let exe_path =
+        std::env::current_exe().unwrap_or_else(|_| PathBuf::from("/usr/local/bin/telemt"));
 
     let unit_path = Path::new("/etc/systemd/system/telemt.service");
     let unit_content = generate_systemd_unit(&exe_path, &config_path);
@@ -183,7 +183,7 @@ fn generate_secret() -> String {
 
 fn generate_config(username: &str, secret: &str, port: u16, domain: &str) -> String {
     format!(
-r#"# Telemt MTProxy — auto-generated config
+        r#"# Telemt MTProxy — auto-generated config
 # Re-run `telemt --init` to regenerate
 
 show_link = ["{username}"]
@@ -246,7 +246,7 @@ tls_full_cert_ttl_secs = 90
 
 [access]
 replay_check_len = 65536
-replay_window_secs = 1800
+replay_window_secs = 120
 ignore_time_skew = false
 
 [access.users]
@@ -266,7 +266,7 @@ weight = 10
 
 fn generate_systemd_unit(exe_path: &Path, config_path: &Path) -> String {
     format!(
-r#"[Unit]
+        r#"[Unit]
 Description=Telemt MTProxy
 Documentation=https://github.com/telemt/telemt
 After=network-online.target
@@ -312,8 +312,10 @@ fn print_links(username: &str, secret: &str, port: u16, domain: &str) {
 
     println!("=== Proxy Links ===");
     println!("[{}]", username);
-    println!("  EE-TLS:  tg://proxy?server=YOUR_SERVER_IP&port={}&secret=ee{}{}", 
-        port, secret, domain_hex);
+    println!(
+        "  EE-TLS:  tg://proxy?server=YOUR_SERVER_IP&port={}&secret=ee{}{}",
+        port, secret, domain_hex
+    );
     println!();
     println!("Replace YOUR_SERVER_IP with your server's public IP.");
     println!("The proxy will auto-detect and display the correct link on startup.");

src/config/defaults.rs

@@ -1,6 +1,6 @@
-use std::collections::HashMap;
 use ipnetwork::IpNetwork;
 use serde::Deserialize;
+use std::collections::HashMap;
 
 // Helper defaults kept private to the config module.
 const DEFAULT_NETWORK_IPV6: Option<bool> = Some(false);
@@ -29,6 +29,8 @@ const DEFAULT_ME_D2C_FLUSH_BATCH_MAX_FRAMES: usize = 32;
 const DEFAULT_ME_D2C_FLUSH_BATCH_MAX_BYTES: usize = 128 * 1024;
 const DEFAULT_ME_D2C_FLUSH_BATCH_MAX_DELAY_US: u64 = 500;
 const DEFAULT_ME_D2C_ACK_FLUSH_IMMEDIATE: bool = true;
+const DEFAULT_ME_QUOTA_SOFT_OVERSHOOT_BYTES: u64 = 64 * 1024;
+const DEFAULT_ME_D2C_FRAME_BUF_SHRINK_THRESHOLD_BYTES: usize = 256 * 1024;
 const DEFAULT_DIRECT_RELAY_COPY_BUF_C2S_BYTES: usize = 64 * 1024;
 const DEFAULT_DIRECT_RELAY_COPY_BUF_S2C_BYTES: usize = 256 * 1024;
 const DEFAULT_ME_WRITER_PICK_SAMPLE_SIZE: u8 = 3;
@@ -69,6 +71,22 @@ pub(crate) fn default_tls_fetch_scope() -> String {
     String::new()
 }
 
+pub(crate) fn default_tls_fetch_attempt_timeout_ms() -> u64 {
+    5_000
+}
+
+pub(crate) fn default_tls_fetch_total_budget_ms() -> u64 {
+    15_000
+}
+
+pub(crate) fn default_tls_fetch_strict_route() -> bool {
+    true
+}
+
+pub(crate) fn default_tls_fetch_profile_cache_ttl_secs() -> u64 {
+    600
+}
+
 pub(crate) fn default_mask_port() -> u16 {
     443
 }
@@ -86,13 +104,31 @@ pub(crate) fn default_replay_check_len() -> usize {
 }
 
 pub(crate) fn default_replay_window_secs() -> u64 {
-    1800
+    // Keep replay cache TTL tight by default to reduce replay surface.
+    // Deployments with higher RTT or longer reconnect jitter can override this in config.
+    120
 }
 
 pub(crate) fn default_handshake_timeout() -> u64 {
     30
 }
 
+pub(crate) fn default_relay_idle_policy_v2_enabled() -> bool {
+    true
+}
+
+pub(crate) fn default_relay_client_idle_soft_secs() -> u64 {
+    120
+}
+
+pub(crate) fn default_relay_client_idle_hard_secs() -> u64 {
+    360
+}
+
+pub(crate) fn default_relay_idle_grace_after_downstream_activity_secs() -> u64 {
+    30
+}
+
 pub(crate) fn default_connect_timeout() -> u64 {
     10
 }
@@ -125,10 +161,7 @@ pub(crate) fn default_weight() -> u16 {
 }
 
 pub(crate) fn default_metrics_whitelist() -> Vec<IpNetwork> {
-    vec![
-        "127.0.0.1/32".parse().unwrap(),
-        "::1/128".parse().unwrap(),
-    ]
+    vec!["127.0.0.1/32".parse().unwrap(), "::1/128".parse().unwrap()]
 }
 
 pub(crate) fn default_api_listen() -> String {
@@ -151,15 +184,27 @@ pub(crate) fn default_api_minimal_runtime_cache_ttl_ms() -> u64 {
     1000
 }
 
-pub(crate) fn default_api_runtime_edge_enabled() -> bool { false }
-pub(crate) fn default_api_runtime_edge_cache_ttl_ms() -> u64 { 1000 }
-pub(crate) fn default_api_runtime_edge_top_n() -> usize { 10 }
-pub(crate) fn default_api_runtime_edge_events_capacity() -> usize { 256 }
+pub(crate) fn default_api_runtime_edge_enabled() -> bool {
+    false
+}
+pub(crate) fn default_api_runtime_edge_cache_ttl_ms() -> u64 {
+    1000
+}
+pub(crate) fn default_api_runtime_edge_top_n() -> usize {
+    10
+}
+pub(crate) fn default_api_runtime_edge_events_capacity() -> usize {
+    256
+}
 
 pub(crate) fn default_proxy_protocol_header_timeout_ms() -> u64 {
     500
 }
 
+pub(crate) fn default_proxy_protocol_trusted_cidrs() -> Vec<IpNetwork> {
+    vec!["0.0.0.0/0".parse().unwrap(), "::/0".parse().unwrap()]
+}
+
 pub(crate) fn default_server_max_connections() -> u32 {
     10_000
 }
@@ -228,6 +273,10 @@ pub(crate) fn default_me2dc_fallback() -> bool {
     true
 }
 
+pub(crate) fn default_me2dc_fast() -> bool {
+    false
+}
+
 pub(crate) fn default_keepalive_interval() -> u64 {
     8
 }
@@ -364,6 +413,14 @@ pub(crate) fn default_me_d2c_ack_flush_immediate() -> bool {
     DEFAULT_ME_D2C_ACK_FLUSH_IMMEDIATE
 }
 
+pub(crate) fn default_me_quota_soft_overshoot_bytes() -> u64 {
+    DEFAULT_ME_QUOTA_SOFT_OVERSHOOT_BYTES
+}
+
+pub(crate) fn default_me_d2c_frame_buf_shrink_threshold_bytes() -> usize {
+    DEFAULT_ME_D2C_FRAME_BUF_SHRINK_THRESHOLD_BYTES
+}
+
 pub(crate) fn default_direct_relay_copy_buf_c2s_bytes() -> usize {
     DEFAULT_DIRECT_RELAY_COPY_BUF_C2S_BYTES
 }
@@ -485,17 +542,67 @@ pub(crate) fn default_tls_full_cert_ttl_secs() -> u64 {
 }
 
 pub(crate) fn default_server_hello_delay_min_ms() -> u64 {
-    0
+    8
 }
 
 pub(crate) fn default_server_hello_delay_max_ms() -> u64 {
-    0
+    24
 }
 
 pub(crate) fn default_alpn_enforce() -> bool {
     true
 }
 
+pub(crate) fn default_mask_shape_hardening() -> bool {
+    true
+}
+
+pub(crate) fn default_mask_shape_hardening_aggressive_mode() -> bool {
+    false
+}
+
+pub(crate) fn default_mask_shape_bucket_floor_bytes() -> usize {
+    512
+}
+
+pub(crate) fn default_mask_shape_bucket_cap_bytes() -> usize {
+    4096
+}
+
+pub(crate) fn default_mask_shape_above_cap_blur() -> bool {
+    false
+}
+
+pub(crate) fn default_mask_shape_above_cap_blur_max_bytes() -> usize {
+    512
+}
+
+#[cfg(not(test))]
+pub(crate) fn default_mask_relay_max_bytes() -> usize {
+    5 * 1024 * 1024
+}
+
+#[cfg(test)]
+pub(crate) fn default_mask_relay_max_bytes() -> usize {
+    32 * 1024
+}
+
+pub(crate) fn default_mask_classifier_prefetch_timeout_ms() -> u64 {
+    5
+}
+
+pub(crate) fn default_mask_timing_normalization_enabled() -> bool {
+    false
+}
+
+pub(crate) fn default_mask_timing_normalization_floor_ms() -> u64 {
+    0
+}
+
+pub(crate) fn default_mask_timing_normalization_ceiling_ms() -> u64 {
+    0
+}
+
 pub(crate) fn default_stun_servers() -> Vec<String> {
     vec![
         "stun.l.google.com:5349".to_string(),

src/config/hot_reload.rs

@@ -31,15 +31,12 @@ use notify::{EventKind, RecursiveMode, Watcher, recommended_watcher};
 use tokio::sync::{mpsc, watch};
 use tracing::{error, info, warn};
 
-use crate::config::{
-    LogLevel, MeBindStaleMode, MeFloorMode, MeSocksKdfPolicy, MeTelemetryLevel,
-    MeWriterPickMode,
-};
 use super::load::{LoadedConfig, ProxyConfig};
+use crate::config::{
+    LogLevel, MeBindStaleMode, MeFloorMode, MeSocksKdfPolicy, MeTelemetryLevel, MeWriterPickMode,
+};
 
-const HOT_RELOAD_STABLE_SNAPSHOTS: u8 = 2;
 const HOT_RELOAD_DEBOUNCE: Duration = Duration::from_millis(50);
-const HOT_RELOAD_STABLE_RECHECK: Duration = Duration::from_millis(75);
 
 // ── Hot fields ────────────────────────────────────────────────────────────────
 
@@ -58,11 +55,6 @@ pub struct HotFields {
     pub me_pool_drain_ttl_secs: u64,
     pub me_instadrain: bool,
     pub me_pool_drain_threshold: u64,
-    pub me_pool_drain_soft_evict_enabled: bool,
-    pub me_pool_drain_soft_evict_grace_secs: u64,
-    pub me_pool_drain_soft_evict_per_writer: u8,
-    pub me_pool_drain_soft_evict_budget_per_core: u16,
-    pub me_pool_drain_soft_evict_cooldown_ms: u64,
     pub me_pool_min_fresh_ratio: f32,
     pub me_reinit_drain_timeout_secs: u64,
     pub me_hardswap_warmup_delay_min_ms: u64,
@@ -114,6 +106,8 @@ pub struct HotFields {
     pub me_d2c_flush_batch_max_bytes: usize,
     pub me_d2c_flush_batch_max_delay_us: u64,
     pub me_d2c_ack_flush_immediate: bool,
+    pub me_quota_soft_overshoot_bytes: u64,
+    pub me_d2c_frame_buf_shrink_threshold_bytes: usize,
     pub direct_relay_copy_buf_c2s_bytes: usize,
     pub direct_relay_copy_buf_s2c_bytes: usize,
     pub me_health_interval_ms_unhealthy: u64,
@@ -146,15 +140,6 @@ impl HotFields {
             me_pool_drain_ttl_secs: cfg.general.me_pool_drain_ttl_secs,
             me_instadrain: cfg.general.me_instadrain,
             me_pool_drain_threshold: cfg.general.me_pool_drain_threshold,
-            me_pool_drain_soft_evict_enabled: cfg.general.me_pool_drain_soft_evict_enabled,
-            me_pool_drain_soft_evict_grace_secs: cfg.general.me_pool_drain_soft_evict_grace_secs,
-            me_pool_drain_soft_evict_per_writer: cfg.general.me_pool_drain_soft_evict_per_writer,
-            me_pool_drain_soft_evict_budget_per_core: cfg
-                .general
-                .me_pool_drain_soft_evict_budget_per_core,
-            me_pool_drain_soft_evict_cooldown_ms: cfg
-                .general
-                .me_pool_drain_soft_evict_cooldown_ms,
             me_pool_min_fresh_ratio: cfg.general.me_pool_min_fresh_ratio,
             me_reinit_drain_timeout_secs: cfg.general.me_reinit_drain_timeout_secs,
             me_hardswap_warmup_delay_min_ms: cfg.general.me_hardswap_warmup_delay_min_ms,
@@ -205,15 +190,11 @@ impl HotFields {
             me_adaptive_floor_min_writers_multi_endpoint: cfg
                 .general
                 .me_adaptive_floor_min_writers_multi_endpoint,
-            me_adaptive_floor_recover_grace_secs: cfg
-                .general
-                .me_adaptive_floor_recover_grace_secs,
+            me_adaptive_floor_recover_grace_secs: cfg.general.me_adaptive_floor_recover_grace_secs,
             me_adaptive_floor_writers_per_core_total: cfg
                 .general
                 .me_adaptive_floor_writers_per_core_total,
-            me_adaptive_floor_cpu_cores_override: cfg
-                .general
-                .me_adaptive_floor_cpu_cores_override,
+            me_adaptive_floor_cpu_cores_override: cfg.general.me_adaptive_floor_cpu_cores_override,
             me_adaptive_floor_max_extra_writers_single_per_core: cfg
                 .general
                 .me_adaptive_floor_max_extra_writers_single_per_core,
@@ -232,14 +213,24 @@ impl HotFields {
             me_adaptive_floor_max_warm_writers_global: cfg
                 .general
                 .me_adaptive_floor_max_warm_writers_global,
-            me_route_backpressure_base_timeout_ms: cfg.general.me_route_backpressure_base_timeout_ms,
-            me_route_backpressure_high_timeout_ms: cfg.general.me_route_backpressure_high_timeout_ms,
-            me_route_backpressure_high_watermark_pct: cfg.general.me_route_backpressure_high_watermark_pct,
+            me_route_backpressure_base_timeout_ms: cfg
+                .general
+                .me_route_backpressure_base_timeout_ms,
+            me_route_backpressure_high_timeout_ms: cfg
+                .general
+                .me_route_backpressure_high_timeout_ms,
+            me_route_backpressure_high_watermark_pct: cfg
+                .general
+                .me_route_backpressure_high_watermark_pct,
             me_reader_route_data_wait_ms: cfg.general.me_reader_route_data_wait_ms,
             me_d2c_flush_batch_max_frames: cfg.general.me_d2c_flush_batch_max_frames,
             me_d2c_flush_batch_max_bytes: cfg.general.me_d2c_flush_batch_max_bytes,
             me_d2c_flush_batch_max_delay_us: cfg.general.me_d2c_flush_batch_max_delay_us,
             me_d2c_ack_flush_immediate: cfg.general.me_d2c_ack_flush_immediate,
+            me_quota_soft_overshoot_bytes: cfg.general.me_quota_soft_overshoot_bytes,
+            me_d2c_frame_buf_shrink_threshold_bytes: cfg
+                .general
+                .me_d2c_frame_buf_shrink_threshold_bytes,
             direct_relay_copy_buf_c2s_bytes: cfg.general.direct_relay_copy_buf_c2s_bytes,
             direct_relay_copy_buf_s2c_bytes: cfg.general.direct_relay_copy_buf_s2c_bytes,
             me_health_interval_ms_unhealthy: cfg.general.me_health_interval_ms_unhealthy,
@@ -346,16 +337,12 @@ impl WatchManifest {
 #[derive(Debug, Default)]
 struct ReloadState {
     applied_snapshot_hash: Option<u64>,
-    candidate_snapshot_hash: Option<u64>,
-    candidate_hits: u8,
 }
 
 impl ReloadState {
     fn new(applied_snapshot_hash: Option<u64>) -> Self {
         Self {
             applied_snapshot_hash,
-            candidate_snapshot_hash: None,
-            candidate_hits: 0,
         }
     }
 
@@ -363,32 +350,8 @@ impl ReloadState {
         self.applied_snapshot_hash == Some(hash)
     }
 
-    fn observe_candidate(&mut self, hash: u64) -> u8 {
-        if self.candidate_snapshot_hash == Some(hash) {
-            self.candidate_hits = self.candidate_hits.saturating_add(1);
-        } else {
-            self.candidate_snapshot_hash = Some(hash);
-            self.candidate_hits = 1;
-        }
-        self.candidate_hits
-    }
-
-    fn reset_candidate(&mut self) {
-        self.candidate_snapshot_hash = None;
-        self.candidate_hits = 0;
-    }
-
     fn mark_applied(&mut self, hash: u64) {
         self.applied_snapshot_hash = Some(hash);
-        self.reset_candidate();
-    }
-
-    fn pending_candidate(&self) -> Option<(u64, u8)> {
-        let hash = self.candidate_snapshot_hash?;
-        if self.candidate_hits < HOT_RELOAD_STABLE_SNAPSHOTS {
-            return Some((hash, self.candidate_hits));
-        }
-        None
     }
 }
 
@@ -481,15 +444,6 @@ fn overlay_hot_fields(old: &ProxyConfig, new: &ProxyConfig) -> ProxyConfig {
     cfg.general.me_pool_drain_ttl_secs = new.general.me_pool_drain_ttl_secs;
     cfg.general.me_instadrain = new.general.me_instadrain;
     cfg.general.me_pool_drain_threshold = new.general.me_pool_drain_threshold;
-    cfg.general.me_pool_drain_soft_evict_enabled = new.general.me_pool_drain_soft_evict_enabled;
-    cfg.general.me_pool_drain_soft_evict_grace_secs =
-        new.general.me_pool_drain_soft_evict_grace_secs;
-    cfg.general.me_pool_drain_soft_evict_per_writer =
-        new.general.me_pool_drain_soft_evict_per_writer;
-    cfg.general.me_pool_drain_soft_evict_budget_per_core =
-        new.general.me_pool_drain_soft_evict_budget_per_core;
-    cfg.general.me_pool_drain_soft_evict_cooldown_ms =
-        new.general.me_pool_drain_soft_evict_cooldown_ms;
     cfg.general.me_pool_min_fresh_ratio = new.general.me_pool_min_fresh_ratio;
     cfg.general.me_reinit_drain_timeout_secs = new.general.me_reinit_drain_timeout_secs;
     cfg.general.me_hardswap_warmup_delay_min_ms = new.general.me_hardswap_warmup_delay_min_ms;
@@ -536,10 +490,14 @@ fn overlay_hot_fields(old: &ProxyConfig, new: &ProxyConfig) -> ProxyConfig {
         new.general.me_adaptive_floor_writers_per_core_total;
     cfg.general.me_adaptive_floor_cpu_cores_override =
         new.general.me_adaptive_floor_cpu_cores_override;
-    cfg.general.me_adaptive_floor_max_extra_writers_single_per_core =
-        new.general.me_adaptive_floor_max_extra_writers_single_per_core;
-    cfg.general.me_adaptive_floor_max_extra_writers_multi_per_core =
-        new.general.me_adaptive_floor_max_extra_writers_multi_per_core;
+    cfg.general
+        .me_adaptive_floor_max_extra_writers_single_per_core = new
+        .general
+        .me_adaptive_floor_max_extra_writers_single_per_core;
+    cfg.general
+        .me_adaptive_floor_max_extra_writers_multi_per_core = new
+        .general
+        .me_adaptive_floor_max_extra_writers_multi_per_core;
     cfg.general.me_adaptive_floor_max_active_writers_per_core =
         new.general.me_adaptive_floor_max_active_writers_per_core;
     cfg.general.me_adaptive_floor_max_warm_writers_per_core =
@@ -559,6 +517,9 @@ fn overlay_hot_fields(old: &ProxyConfig, new: &ProxyConfig) -> ProxyConfig {
     cfg.general.me_d2c_flush_batch_max_bytes = new.general.me_d2c_flush_batch_max_bytes;
     cfg.general.me_d2c_flush_batch_max_delay_us = new.general.me_d2c_flush_batch_max_delay_us;
     cfg.general.me_d2c_ack_flush_immediate = new.general.me_d2c_ack_flush_immediate;
+    cfg.general.me_quota_soft_overshoot_bytes = new.general.me_quota_soft_overshoot_bytes;
+    cfg.general.me_d2c_frame_buf_shrink_threshold_bytes =
+        new.general.me_d2c_frame_buf_shrink_threshold_bytes;
     cfg.general.direct_relay_copy_buf_c2s_bytes = new.general.direct_relay_copy_buf_c2s_bytes;
     cfg.general.direct_relay_copy_buf_s2c_bytes = new.general.direct_relay_copy_buf_s2c_bytes;
     cfg.general.me_health_interval_ms_unhealthy = new.general.me_health_interval_ms_unhealthy;
@@ -598,8 +559,7 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
         || old.server.api.minimal_runtime_cache_ttl_ms
             != new.server.api.minimal_runtime_cache_ttl_ms
         || old.server.api.runtime_edge_enabled != new.server.api.runtime_edge_enabled
-        || old.server.api.runtime_edge_cache_ttl_ms
-            != new.server.api.runtime_edge_cache_ttl_ms
+        || old.server.api.runtime_edge_cache_ttl_ms != new.server.api.runtime_edge_cache_ttl_ms
         || old.server.api.runtime_edge_top_n != new.server.api.runtime_edge_top_n
         || old.server.api.runtime_edge_events_capacity
             != new.server.api.runtime_edge_events_capacity
@@ -615,8 +575,6 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
         || old.server.listen_tcp != new.server.listen_tcp
         || old.server.listen_unix_sock != new.server.listen_unix_sock
         || old.server.listen_unix_sock_perm != new.server.listen_unix_sock_perm
-        || old.server.max_connections != new.server.max_connections
-        || old.server.accept_permit_timeout_ms != new.server.accept_permit_timeout_ms
     {
         warned = true;
         warn!("config reload: server listener settings changed; restart required");
@@ -637,6 +595,22 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
         || old.censorship.tls_full_cert_ttl_secs != new.censorship.tls_full_cert_ttl_secs
         || old.censorship.alpn_enforce != new.censorship.alpn_enforce
         || old.censorship.mask_proxy_protocol != new.censorship.mask_proxy_protocol
+        || old.censorship.mask_shape_hardening != new.censorship.mask_shape_hardening
+        || old.censorship.mask_shape_bucket_floor_bytes
+            != new.censorship.mask_shape_bucket_floor_bytes
+        || old.censorship.mask_shape_bucket_cap_bytes != new.censorship.mask_shape_bucket_cap_bytes
+        || old.censorship.mask_shape_above_cap_blur != new.censorship.mask_shape_above_cap_blur
+        || old.censorship.mask_shape_above_cap_blur_max_bytes
+            != new.censorship.mask_shape_above_cap_blur_max_bytes
+        || old.censorship.mask_relay_max_bytes != new.censorship.mask_relay_max_bytes
+        || old.censorship.mask_classifier_prefetch_timeout_ms
+            != new.censorship.mask_classifier_prefetch_timeout_ms
+        || old.censorship.mask_timing_normalization_enabled
+            != new.censorship.mask_timing_normalization_enabled
+        || old.censorship.mask_timing_normalization_floor_ms
+            != new.censorship.mask_timing_normalization_floor_ms
+        || old.censorship.mask_timing_normalization_ceiling_ms
+            != new.censorship.mask_timing_normalization_ceiling_ms
     {
         warned = true;
         warn!("config reload: censorship settings changed; restart required");
@@ -688,10 +662,6 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
         warned = true;
         warn!("config reload: general.me_route_no_writer_* changed; restart required");
     }
-    if old.general.me_c2me_send_timeout_ms != new.general.me_c2me_send_timeout_ms {
-        warned = true;
-        warn!("config reload: general.me_c2me_send_timeout_ms changed; restart required");
-    }
     if old.general.unknown_dc_log_path != new.general.unknown_dc_log_path
         || old.general.unknown_dc_file_log_enabled != new.general.unknown_dc_file_log_enabled
     {
@@ -702,9 +672,11 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
         warned = true;
         warn!("config reload: general.me_init_retry_attempts changed; restart required");
     }
-    if old.general.me2dc_fallback != new.general.me2dc_fallback {
+    if old.general.me2dc_fallback != new.general.me2dc_fallback
+        || old.general.me2dc_fast != new.general.me2dc_fast
+    {
         warned = true;
-        warn!("config reload: general.me2dc_fallback changed; restart required");
+        warn!("config reload: general.me2dc_fallback/me2dc_fast changed; restart required");
     }
     if old.general.proxy_config_v4_cache_path != new.general.proxy_config_v4_cache_path
         || old.general.proxy_config_v6_cache_path != new.general.proxy_config_v6_cache_path
@@ -886,25 +858,6 @@ fn log_changes(
             old_hot.me_pool_drain_threshold, new_hot.me_pool_drain_threshold,
         );
     }
-    if old_hot.me_pool_drain_soft_evict_enabled != new_hot.me_pool_drain_soft_evict_enabled
-        || old_hot.me_pool_drain_soft_evict_grace_secs
-            != new_hot.me_pool_drain_soft_evict_grace_secs
-        || old_hot.me_pool_drain_soft_evict_per_writer
-            != new_hot.me_pool_drain_soft_evict_per_writer
-        || old_hot.me_pool_drain_soft_evict_budget_per_core
-            != new_hot.me_pool_drain_soft_evict_budget_per_core
-        || old_hot.me_pool_drain_soft_evict_cooldown_ms
-            != new_hot.me_pool_drain_soft_evict_cooldown_ms
-    {
-        info!(
-            "config reload: me_pool_drain_soft_evict: enabled={} grace={}s per_writer={} budget_per_core={} cooldown={}ms",
-            new_hot.me_pool_drain_soft_evict_enabled,
-            new_hot.me_pool_drain_soft_evict_grace_secs,
-            new_hot.me_pool_drain_soft_evict_per_writer,
-            new_hot.me_pool_drain_soft_evict_budget_per_core,
-            new_hot.me_pool_drain_soft_evict_cooldown_ms
-        );
-    }
 
     if (old_hot.me_pool_min_fresh_ratio - new_hot.me_pool_min_fresh_ratio).abs() > f32::EPSILON {
         info!(
@@ -938,8 +891,7 @@ fn log_changes(
     {
         info!(
             "config reload: me_bind_stale: mode={:?} ttl={}s",
-            new_hot.me_bind_stale_mode,
-            new_hot.me_bind_stale_ttl_secs
+            new_hot.me_bind_stale_mode, new_hot.me_bind_stale_ttl_secs
         );
     }
     if old_hot.me_secret_atomic_snapshot != new_hot.me_secret_atomic_snapshot
@@ -1019,8 +971,7 @@ fn log_changes(
     if old_hot.me_socks_kdf_policy != new_hot.me_socks_kdf_policy {
         info!(
             "config reload: me_socks_kdf_policy: {:?} → {:?}",
-            old_hot.me_socks_kdf_policy,
-            new_hot.me_socks_kdf_policy,
+            old_hot.me_socks_kdf_policy, new_hot.me_socks_kdf_policy,
         );
     }
 
@@ -1074,8 +1025,7 @@ fn log_changes(
         || old_hot.me_route_backpressure_high_watermark_pct
             != new_hot.me_route_backpressure_high_watermark_pct
         || old_hot.me_reader_route_data_wait_ms != new_hot.me_reader_route_data_wait_ms
-        || old_hot.me_health_interval_ms_unhealthy
-            != new_hot.me_health_interval_ms_unhealthy
+        || old_hot.me_health_interval_ms_unhealthy != new_hot.me_health_interval_ms_unhealthy
         || old_hot.me_health_interval_ms_healthy != new_hot.me_health_interval_ms_healthy
         || old_hot.me_admission_poll_ms != new_hot.me_admission_poll_ms
         || old_hot.me_warn_rate_limit_ms != new_hot.me_warn_rate_limit_ms
@@ -1097,34 +1047,47 @@ fn log_changes(
         || old_hot.me_d2c_flush_batch_max_bytes != new_hot.me_d2c_flush_batch_max_bytes
         || old_hot.me_d2c_flush_batch_max_delay_us != new_hot.me_d2c_flush_batch_max_delay_us
         || old_hot.me_d2c_ack_flush_immediate != new_hot.me_d2c_ack_flush_immediate
+        || old_hot.me_quota_soft_overshoot_bytes != new_hot.me_quota_soft_overshoot_bytes
+        || old_hot.me_d2c_frame_buf_shrink_threshold_bytes
+            != new_hot.me_d2c_frame_buf_shrink_threshold_bytes
         || old_hot.direct_relay_copy_buf_c2s_bytes != new_hot.direct_relay_copy_buf_c2s_bytes
         || old_hot.direct_relay_copy_buf_s2c_bytes != new_hot.direct_relay_copy_buf_s2c_bytes
     {
         info!(
-            "config reload: relay_tuning: me_d2c_frames={} me_d2c_bytes={} me_d2c_delay_us={} me_ack_flush_immediate={} direct_buf_c2s={} direct_buf_s2c={}",
+            "config reload: relay_tuning: me_d2c_frames={} me_d2c_bytes={} me_d2c_delay_us={} me_ack_flush_immediate={} me_quota_soft_overshoot_bytes={} me_d2c_frame_buf_shrink_threshold_bytes={} direct_buf_c2s={} direct_buf_s2c={}",
             new_hot.me_d2c_flush_batch_max_frames,
             new_hot.me_d2c_flush_batch_max_bytes,
             new_hot.me_d2c_flush_batch_max_delay_us,
             new_hot.me_d2c_ack_flush_immediate,
+            new_hot.me_quota_soft_overshoot_bytes,
+            new_hot.me_d2c_frame_buf_shrink_threshold_bytes,
             new_hot.direct_relay_copy_buf_c2s_bytes,
             new_hot.direct_relay_copy_buf_s2c_bytes,
         );
     }
 
     if old_hot.users != new_hot.users {
-        let mut added: Vec<&String> = new_hot.users.keys()
+        let mut added: Vec<&String> = new_hot
+            .users
+            .keys()
             .filter(|u| !old_hot.users.contains_key(*u))
             .collect();
         added.sort();
 
-        let mut removed: Vec<&String> = old_hot.users.keys()
+        let mut removed: Vec<&String> = old_hot
+            .users
+            .keys()
             .filter(|u| !new_hot.users.contains_key(*u))
             .collect();
         removed.sort();
 
-        let mut changed: Vec<&String> = new_hot.users.keys()
+        let mut changed: Vec<&String> = new_hot
+            .users
+            .keys()
             .filter(|u| {
-                old_hot.users.get(*u)
+                old_hot
+                    .users
+                    .get(*u)
                     .map(|s| s != &new_hot.users[*u])
                     .unwrap_or(false)
             })
@@ -1134,10 +1097,18 @@ fn log_changes(
         if !added.is_empty() {
             info!(
                 "config reload: users added: [{}]",
-                added.iter().map(|s| s.as_str()).collect::<Vec<_>>().join(", ")
+                added
+                    .iter()
+                    .map(|s| s.as_str())
+                    .collect::<Vec<_>>()
+                    .join(", ")
             );
             let host = resolve_link_host(new_cfg, detected_ip_v4, detected_ip_v6);
-            let port = new_cfg.general.links.public_port.unwrap_or(new_cfg.server.port);
+            let port = new_cfg
+                .general
+                .links
+                .public_port
+                .unwrap_or(new_cfg.server.port);
             for user in &added {
                 if let Some(secret) = new_hot.users.get(*user) {
                     print_user_links(user, secret, &host, port, new_cfg);
@@ -1147,13 +1118,21 @@ fn log_changes(
         if !removed.is_empty() {
             info!(
                 "config reload: users removed: [{}]",
-                removed.iter().map(|s| s.as_str()).collect::<Vec<_>>().join(", ")
+                removed
+                    .iter()
+                    .map(|s| s.as_str())
+                    .collect::<Vec<_>>()
+                    .join(", ")
             );
         }
         if !changed.is_empty() {
             info!(
                 "config reload: users secret changed: [{}]",
-                changed.iter().map(|s| s.as_str()).collect::<Vec<_>>().join(", ")
+                changed
+                    .iter()
+                    .map(|s| s.as_str())
+                    .collect::<Vec<_>>()
+                    .join(", ")
             );
         }
     }
@@ -1184,8 +1163,7 @@ fn log_changes(
     }
     if old_hot.user_max_unique_ips_global_each != new_hot.user_max_unique_ips_global_each
         || old_hot.user_max_unique_ips_mode != new_hot.user_max_unique_ips_mode
-        || old_hot.user_max_unique_ips_window_secs
-            != new_hot.user_max_unique_ips_window_secs
+        || old_hot.user_max_unique_ips_window_secs != new_hot.user_max_unique_ips_window_secs
     {
         info!(
             "config reload: user_max_unique_ips policy global_each={} mode={:?} window={}s",
@@ -1208,7 +1186,6 @@ fn reload_config(
     let loaded = match ProxyConfig::load_with_metadata(config_path) {
         Ok(loaded) => loaded,
         Err(e) => {
-            reload_state.reset_candidate();
             error!("config reload: failed to parse {:?}: {}", config_path, e);
             return None;
         }
@@ -1221,8 +1198,10 @@ fn reload_config(
     let next_manifest = WatchManifest::from_source_files(&source_files);
 
     if let Err(e) = new_cfg.validate() {
-        reload_state.reset_candidate();
-        error!("config reload: validation failed: {}; keeping old config", e);
+        error!(
+            "config reload: validation failed: {}; keeping old config",
+            e
+        );
         return Some(next_manifest);
     }
 
@@ -1230,17 +1209,6 @@ fn reload_config(
         return Some(next_manifest);
     }
 
-    let candidate_hits = reload_state.observe_candidate(rendered_hash);
-    if candidate_hits < HOT_RELOAD_STABLE_SNAPSHOTS {
-        info!(
-            snapshot_hash = rendered_hash,
-            candidate_hits,
-            required_hits = HOT_RELOAD_STABLE_SNAPSHOTS,
-            "config reload: candidate snapshot observed but not stable yet"
-        );
-        return Some(next_manifest);
-    }
-
     let old_cfg = config_tx.borrow().clone();
     let applied_cfg = overlay_hot_fields(&old_cfg, &new_cfg);
     let old_hot = HotFields::from_config(&old_cfg);
@@ -1260,7 +1228,6 @@ fn reload_config(
     if old_hot.dns_overrides != applied_hot.dns_overrides
         && let Err(e) = crate::network::dns_overrides::install_entries(&applied_hot.dns_overrides)
     {
-        reload_state.reset_candidate();
         error!(
             "config reload: invalid network.dns_overrides: {}; keeping old config",
             e
@@ -1281,73 +1248,6 @@ fn reload_config(
     Some(next_manifest)
 }
 
-async fn reload_with_internal_stable_rechecks(
-    config_path: &PathBuf,
-    config_tx: &watch::Sender<Arc<ProxyConfig>>,
-    log_tx: &watch::Sender<LogLevel>,
-    detected_ip_v4: Option<IpAddr>,
-    detected_ip_v6: Option<IpAddr>,
-    reload_state: &mut ReloadState,
-) -> Option<WatchManifest> {
-    let mut next_manifest = reload_config(
-        config_path,
-        config_tx,
-        log_tx,
-        detected_ip_v4,
-        detected_ip_v6,
-        reload_state,
-    );
-    let mut rechecks_left = HOT_RELOAD_STABLE_SNAPSHOTS.saturating_sub(1);
-
-    while rechecks_left > 0 {
-        let Some((snapshot_hash, candidate_hits)) = reload_state.pending_candidate() else {
-            break;
-        };
-
-        info!(
-            snapshot_hash,
-            candidate_hits,
-            required_hits = HOT_RELOAD_STABLE_SNAPSHOTS,
-            rechecks_left,
-            recheck_delay_ms = HOT_RELOAD_STABLE_RECHECK.as_millis(),
-            "config reload: scheduling internal stable recheck"
-        );
-        tokio::time::sleep(HOT_RELOAD_STABLE_RECHECK).await;
-
-        let recheck_manifest = reload_config(
-            config_path,
-            config_tx,
-            log_tx,
-            detected_ip_v4,
-            detected_ip_v6,
-            reload_state,
-        );
-        if recheck_manifest.is_some() {
-            next_manifest = recheck_manifest;
-        }
-
-        if reload_state.is_applied(snapshot_hash) {
-            info!(
-                snapshot_hash,
-                "config reload: applied after internal stable recheck"
-            );
-            break;
-        }
-
-        if reload_state.pending_candidate().is_none() {
-            info!(
-                snapshot_hash,
-                "config reload: internal stable recheck aborted"
-            );
-            break;
-        }
-
-        rechecks_left = rechecks_left.saturating_sub(1);
-    }
-
-    next_manifest
-}
-
 // ── Public API ────────────────────────────────────────────────────────────────
 
 /// Spawn the hot-reload watcher task.
@@ -1383,9 +1283,13 @@ pub fn spawn_config_watcher(
 
         let tx_inotify = notify_tx.clone();
         let manifest_for_inotify = manifest_state.clone();
-        let mut inotify_watcher = match recommended_watcher(move |res: notify::Result<notify::Event>| {
+        let mut inotify_watcher =
+            match recommended_watcher(move |res: notify::Result<notify::Event>| {
                 let Ok(event) = res else { return };
-            if !matches!(event.kind, EventKind::Modify(_) | EventKind::Create(_) | EventKind::Remove(_)) {
+                if !matches!(
+                    event.kind,
+                    EventKind::Modify(_) | EventKind::Create(_) | EventKind::Remove(_)
+                ) {
                     return;
                 }
                 let is_our_file = manifest_for_inotify
@@ -1417,7 +1321,10 @@ pub fn spawn_config_watcher(
         let mut poll_watcher = match notify::poll::PollWatcher::new(
             move |res: notify::Result<notify::Event>| {
                 let Ok(event) = res else { return };
-                if !matches!(event.kind, EventKind::Modify(_) | EventKind::Create(_) | EventKind::Remove(_)) {
+                if !matches!(
+                    event.kind,
+                    EventKind::Modify(_) | EventKind::Create(_) | EventKind::Remove(_)
+                ) {
                     return;
                 }
                 let is_our_file = manifest_for_poll
@@ -1465,22 +1372,36 @@ pub fn spawn_config_watcher(
                 }
             }
             #[cfg(not(unix))]
-            if notify_rx.recv().await.is_none() { break; }
+            if notify_rx.recv().await.is_none() {
+                break;
+            }
 
             // Debounce: drain extra events that arrive within a short quiet window.
             tokio::time::sleep(HOT_RELOAD_DEBOUNCE).await;
             while notify_rx.try_recv().is_ok() {}
 
-            if let Some(next_manifest) = reload_with_internal_stable_rechecks(
+            let mut next_manifest = reload_config(
                 &config_path,
                 &config_tx,
                 &log_tx,
                 detected_ip_v4,
                 detected_ip_v6,
                 &mut reload_state,
-            )
-            .await
-            {
+            );
+            if next_manifest.is_none() {
+                tokio::time::sleep(HOT_RELOAD_DEBOUNCE).await;
+                while notify_rx.try_recv().is_ok() {}
+                next_manifest = reload_config(
+                    &config_path,
+                    &config_tx,
+                    &log_tx,
+                    detected_ip_v4,
+                    detected_ip_v6,
+                    &mut reload_state,
+                );
+            }
+
+            if let Some(next_manifest) = next_manifest {
                 apply_watch_manifest(
                     inotify_watcher.as_mut(),
                     poll_watcher.as_mut(),
@@ -1555,7 +1476,10 @@ mod tests {
         new.server.port = old.server.port.saturating_add(1);
 
         let applied = overlay_hot_fields(&old, &new);
-        assert_eq!(HotFields::from_config(&old), HotFields::from_config(&applied));
+        assert_eq!(
+            HotFields::from_config(&old),
+            HotFields::from_config(&applied)
+        );
         assert_eq!(applied.server.port, old.server.port);
     }
 
@@ -1574,7 +1498,10 @@ mod tests {
             applied.general.me_bind_stale_mode,
             new.general.me_bind_stale_mode
         );
-        assert_ne!(HotFields::from_config(&old), HotFields::from_config(&applied));
+        assert_ne!(
+            HotFields::from_config(&old),
+            HotFields::from_config(&applied)
+        );
     }
 
     #[test]
@@ -1588,7 +1515,10 @@ mod tests {
             applied.general.me_keepalive_interval_secs,
             old.general.me_keepalive_interval_secs
         );
-        assert_eq!(HotFields::from_config(&old), HotFields::from_config(&applied));
+        assert_eq!(
+            HotFields::from_config(&old),
+            HotFields::from_config(&applied)
+        );
     }
 
     #[test]
@@ -1600,69 +1530,35 @@ mod tests {
 
         let applied = overlay_hot_fields(&old, &new);
         assert_eq!(applied.general.hardswap, new.general.hardswap);
-        assert_eq!(applied.general.use_middle_proxy, old.general.use_middle_proxy);
+        assert_eq!(
+            applied.general.use_middle_proxy,
+            old.general.use_middle_proxy
+        );
         assert!(!config_equal(&applied, &new));
     }
 
     #[test]
-    fn reload_requires_stable_snapshot_before_hot_apply() {
+    fn reload_applies_hot_change_on_first_observed_snapshot() {
         let initial_tag = "11111111111111111111111111111111";
         let final_tag = "22222222222222222222222222222222";
         let path = temp_config_path("telemt_hot_reload_stable");
 
         write_reload_config(&path, Some(initial_tag), None);
         let initial_cfg = Arc::new(ProxyConfig::load(&path).unwrap());
-        let initial_hash = ProxyConfig::load_with_metadata(&path).unwrap().rendered_hash;
-        let (config_tx, _config_rx) = watch::channel(initial_cfg.clone());
-        let (log_tx, _log_rx) = watch::channel(initial_cfg.general.log_level.clone());
-        let mut reload_state = ReloadState::new(Some(initial_hash));
-
-        write_reload_config(&path, None, None);
-        reload_config(&path, &config_tx, &log_tx, None, None, &mut reload_state).unwrap();
-        assert_eq!(
-            config_tx.borrow().general.ad_tag.as_deref(),
-            Some(initial_tag)
-        );
-
-        write_reload_config(&path, Some(final_tag), None);
-        reload_config(&path, &config_tx, &log_tx, None, None, &mut reload_state).unwrap();
-        assert_eq!(
-            config_tx.borrow().general.ad_tag.as_deref(),
-            Some(initial_tag)
-        );
-
-        reload_config(&path, &config_tx, &log_tx, None, None, &mut reload_state).unwrap();
-        assert_eq!(config_tx.borrow().general.ad_tag.as_deref(), Some(final_tag));
-
-        let _ = std::fs::remove_file(path);
-    }
-
-    #[tokio::test]
-    async fn reload_cycle_applies_after_single_external_event() {
-        let initial_tag = "10101010101010101010101010101010";
-        let final_tag = "20202020202020202020202020202020";
-        let path = temp_config_path("telemt_hot_reload_single_event");
-
-        write_reload_config(&path, Some(initial_tag), None);
-        let initial_cfg = Arc::new(ProxyConfig::load(&path).unwrap());
-        let initial_hash = ProxyConfig::load_with_metadata(&path).unwrap().rendered_hash;
+        let initial_hash = ProxyConfig::load_with_metadata(&path)
+            .unwrap()
+            .rendered_hash;
         let (config_tx, _config_rx) = watch::channel(initial_cfg.clone());
         let (log_tx, _log_rx) = watch::channel(initial_cfg.general.log_level.clone());
         let mut reload_state = ReloadState::new(Some(initial_hash));
 
         write_reload_config(&path, Some(final_tag), None);
-        reload_with_internal_stable_rechecks(
-            &path,
-            &config_tx,
-            &log_tx,
-            None,
-            None,
-            &mut reload_state,
-        )
-        .await
-        .unwrap();
+        reload_config(&path, &config_tx, &log_tx, None, None, &mut reload_state).unwrap();
+        assert_eq!(
+            config_tx.borrow().general.ad_tag.as_deref(),
+            Some(final_tag)
+        );
 
-        assert_eq!(config_tx.borrow().general.ad_tag.as_deref(), Some(final_tag));
         let _ = std::fs::remove_file(path);
     }
 
@@ -1674,14 +1570,15 @@ mod tests {
 
         write_reload_config(&path, Some(initial_tag), None);
         let initial_cfg = Arc::new(ProxyConfig::load(&path).unwrap());
-        let initial_hash = ProxyConfig::load_with_metadata(&path).unwrap().rendered_hash;
+        let initial_hash = ProxyConfig::load_with_metadata(&path)
+            .unwrap()
+            .rendered_hash;
         let (config_tx, _config_rx) = watch::channel(initial_cfg.clone());
         let (log_tx, _log_rx) = watch::channel(initial_cfg.general.log_level.clone());
         let mut reload_state = ReloadState::new(Some(initial_hash));
 
         write_reload_config(&path, Some(final_tag), Some(initial_cfg.server.port + 1));
         reload_config(&path, &config_tx, &log_tx, None, None, &mut reload_state).unwrap();
-        reload_config(&path, &config_tx, &log_tx, None, None, &mut reload_state).unwrap();
 
         let applied = config_tx.borrow().clone();
         assert_eq!(applied.general.ad_tag.as_deref(), Some(final_tag));
@@ -1689,4 +1586,36 @@ mod tests {
 
         let _ = std::fs::remove_file(path);
     }
+
+    #[test]
+    fn reload_recovers_after_parse_error_on_next_attempt() {
+        let initial_tag = "cccccccccccccccccccccccccccccccc";
+        let final_tag = "dddddddddddddddddddddddddddddddd";
+        let path = temp_config_path("telemt_hot_reload_parse_recovery");
+
+        write_reload_config(&path, Some(initial_tag), None);
+        let initial_cfg = Arc::new(ProxyConfig::load(&path).unwrap());
+        let initial_hash = ProxyConfig::load_with_metadata(&path)
+            .unwrap()
+            .rendered_hash;
+        let (config_tx, _config_rx) = watch::channel(initial_cfg.clone());
+        let (log_tx, _log_rx) = watch::channel(initial_cfg.general.log_level.clone());
+        let mut reload_state = ReloadState::new(Some(initial_hash));
+
+        std::fs::write(&path, "[access.users\nuser = \"broken\"\n").unwrap();
+        assert!(reload_config(&path, &config_tx, &log_tx, None, None, &mut reload_state).is_none());
+        assert_eq!(
+            config_tx.borrow().general.ad_tag.as_deref(),
+            Some(initial_tag)
+        );
+
+        write_reload_config(&path, Some(final_tag), None);
+        reload_config(&path, &config_tx, &log_tx, None, None, &mut reload_state).unwrap();
+        assert_eq!(
+            config_tx.borrow().general.ad_tag.as_deref(),
+            Some(final_tag)
+        );
+
+        let _ = std::fs::remove_file(path);
+    }
 }

src/config/load.rs

@@ -1,11 +1,11 @@
 #![allow(deprecated)]
 
-use std::collections::{BTreeSet, HashMap};
+use std::collections::{BTreeSet, HashMap, HashSet};
 use std::hash::{DefaultHasher, Hash, Hasher};
 use std::net::{IpAddr, SocketAddr};
 use std::path::{Path, PathBuf};
 
-use rand::Rng;
+use rand::RngExt;
 use serde::{Deserialize, Serialize};
 use shadowsocks::config::ServerConfig as ShadowsocksServerConfig;
 use tracing::warn;
@@ -346,6 +346,12 @@ impl ProxyConfig {
             ));
         }
 
+        if config.timeouts.tg_connect == 0 {
+            return Err(ProxyError::Config(
+                "timeouts.tg_connect must be > 0".to_string(),
+            ));
+        }
+
         if config.general.upstream_unhealthy_fail_threshold == 0 {
             return Err(ProxyError::Config(
                 "general.upstream_unhealthy_fail_threshold must be > 0".to_string(),
@@ -360,6 +366,149 @@ impl ProxyConfig {
             ));
         }
 
+        if config.timeouts.client_handshake == 0 {
+            return Err(ProxyError::Config(
+                "timeouts.client_handshake must be > 0".to_string(),
+            ));
+        }
+
+        let handshake_timeout_ms = config
+            .timeouts
+            .client_handshake
+            .checked_mul(1000)
+            .ok_or_else(|| {
+                ProxyError::Config(
+                    "timeouts.client_handshake is too large to validate milliseconds budget"
+                        .to_string(),
+                )
+            })?;
+
+        if config.censorship.server_hello_delay_max_ms >= handshake_timeout_ms {
+            return Err(ProxyError::Config(
+                "censorship.server_hello_delay_max_ms must be < timeouts.client_handshake * 1000"
+                    .to_string(),
+            ));
+        }
+
+        if config.censorship.mask_shape_bucket_floor_bytes == 0 {
+            return Err(ProxyError::Config(
+                "censorship.mask_shape_bucket_floor_bytes must be > 0".to_string(),
+            ));
+        }
+
+        if config.censorship.mask_shape_bucket_cap_bytes
+            < config.censorship.mask_shape_bucket_floor_bytes
+        {
+            return Err(ProxyError::Config(
+                "censorship.mask_shape_bucket_cap_bytes must be >= censorship.mask_shape_bucket_floor_bytes"
+                    .to_string(),
+            ));
+        }
+
+        if config.censorship.mask_shape_above_cap_blur && !config.censorship.mask_shape_hardening {
+            return Err(ProxyError::Config(
+                "censorship.mask_shape_above_cap_blur requires censorship.mask_shape_hardening = true"
+                    .to_string(),
+            ));
+        }
+
+        if config.censorship.mask_shape_hardening_aggressive_mode
+            && !config.censorship.mask_shape_hardening
+        {
+            return Err(ProxyError::Config(
+                "censorship.mask_shape_hardening_aggressive_mode requires censorship.mask_shape_hardening = true"
+                    .to_string(),
+            ));
+        }
+
+        if config.censorship.mask_shape_above_cap_blur
+            && config.censorship.mask_shape_above_cap_blur_max_bytes == 0
+        {
+            return Err(ProxyError::Config(
+                "censorship.mask_shape_above_cap_blur_max_bytes must be > 0 when censorship.mask_shape_above_cap_blur is enabled"
+                    .to_string(),
+            ));
+        }
+
+        if config.censorship.mask_shape_above_cap_blur_max_bytes > 1_048_576 {
+            return Err(ProxyError::Config(
+                "censorship.mask_shape_above_cap_blur_max_bytes must be <= 1048576".to_string(),
+            ));
+        }
+
+        if config.censorship.mask_relay_max_bytes == 0 {
+            return Err(ProxyError::Config(
+                "censorship.mask_relay_max_bytes must be > 0".to_string(),
+            ));
+        }
+
+        if config.censorship.mask_relay_max_bytes > 67_108_864 {
+            return Err(ProxyError::Config(
+                "censorship.mask_relay_max_bytes must be <= 67108864".to_string(),
+            ));
+        }
+
+        if !(5..=50).contains(&config.censorship.mask_classifier_prefetch_timeout_ms) {
+            return Err(ProxyError::Config(
+                "censorship.mask_classifier_prefetch_timeout_ms must be within [5, 50]".to_string(),
+            ));
+        }
+
+        if config.censorship.mask_timing_normalization_ceiling_ms
+            < config.censorship.mask_timing_normalization_floor_ms
+        {
+            return Err(ProxyError::Config(
+                "censorship.mask_timing_normalization_ceiling_ms must be >= censorship.mask_timing_normalization_floor_ms"
+                    .to_string(),
+            ));
+        }
+
+        if config.censorship.mask_timing_normalization_enabled
+            && config.censorship.mask_timing_normalization_floor_ms == 0
+        {
+            return Err(ProxyError::Config(
+                "censorship.mask_timing_normalization_floor_ms must be > 0 when censorship.mask_timing_normalization_enabled is true"
+                    .to_string(),
+            ));
+        }
+
+        if config.censorship.mask_timing_normalization_ceiling_ms > 60_000 {
+            return Err(ProxyError::Config(
+                "censorship.mask_timing_normalization_ceiling_ms must be <= 60000".to_string(),
+            ));
+        }
+
+        if config.timeouts.relay_client_idle_soft_secs == 0 {
+            return Err(ProxyError::Config(
+                "timeouts.relay_client_idle_soft_secs must be > 0".to_string(),
+            ));
+        }
+
+        if config.timeouts.relay_client_idle_hard_secs == 0 {
+            return Err(ProxyError::Config(
+                "timeouts.relay_client_idle_hard_secs must be > 0".to_string(),
+            ));
+        }
+
+        if config.timeouts.relay_client_idle_hard_secs < config.timeouts.relay_client_idle_soft_secs
+        {
+            return Err(ProxyError::Config(
+                "timeouts.relay_client_idle_hard_secs must be >= timeouts.relay_client_idle_soft_secs"
+                    .to_string(),
+            ));
+        }
+
+        if config
+            .timeouts
+            .relay_idle_grace_after_downstream_activity_secs
+            > config.timeouts.relay_client_idle_hard_secs
+        {
+            return Err(ProxyError::Config(
+                "timeouts.relay_idle_grace_after_downstream_activity_secs must be <= timeouts.relay_client_idle_hard_secs"
+                    .to_string(),
+            ));
+        }
+
         if config.general.me_writer_cmd_channel_capacity == 0 {
             return Err(ProxyError::Config(
                 "general.me_writer_cmd_channel_capacity must be > 0".to_string(),
@@ -408,6 +557,21 @@ impl ProxyConfig {
             ));
         }
 
+        if config.general.me_quota_soft_overshoot_bytes > 16 * 1024 * 1024 {
+            return Err(ProxyError::Config(
+                "general.me_quota_soft_overshoot_bytes must be within [0, 16777216]".to_string(),
+            ));
+        }
+
+        if !(4096..=16 * 1024 * 1024)
+            .contains(&config.general.me_d2c_frame_buf_shrink_threshold_bytes)
+        {
+            return Err(ProxyError::Config(
+                "general.me_d2c_frame_buf_shrink_threshold_bytes must be within [4096, 16777216]"
+                    .to_string(),
+            ));
+        }
+
         if !(4096..=1024 * 1024).contains(&config.general.direct_relay_copy_buf_c2s_bytes) {
             return Err(ProxyError::Config(
                 "general.direct_relay_copy_buf_c2s_bytes must be within [4096, 1048576]"
@@ -648,7 +812,8 @@ impl ProxyConfig {
         }
         if config.general.me_route_backpressure_base_timeout_ms > 5000 {
             return Err(ProxyError::Config(
-                "general.me_route_backpressure_base_timeout_ms must be within [1, 5000]".to_string(),
+                "general.me_route_backpressure_base_timeout_ms must be within [1, 5000]"
+                    .to_string(),
             ));
         }
 
@@ -661,7 +826,8 @@ impl ProxyConfig {
         }
         if config.general.me_route_backpressure_high_timeout_ms > 5000 {
             return Err(ProxyError::Config(
-                "general.me_route_backpressure_high_timeout_ms must be within [1, 5000]".to_string(),
+                "general.me_route_backpressure_high_timeout_ms must be within [1, 5000]"
+                    .to_string(),
             ));
         }
 
@@ -817,6 +983,28 @@ impl ProxyConfig {
         // Normalize optional TLS fetch scope: whitespace-only values disable scoped routing.
         config.censorship.tls_fetch_scope = config.censorship.tls_fetch_scope.trim().to_string();
 
+        if config.censorship.tls_fetch.profiles.is_empty() {
+            config.censorship.tls_fetch.profiles = TlsFetchConfig::default().profiles;
+        } else {
+            let mut seen = HashSet::new();
+            config
+                .censorship
+                .tls_fetch
+                .profiles
+                .retain(|profile| seen.insert(*profile));
+        }
+
+        if config.censorship.tls_fetch.attempt_timeout_ms == 0 {
+            return Err(ProxyError::Config(
+                "censorship.tls_fetch.attempt_timeout_ms must be > 0".to_string(),
+            ));
+        }
+        if config.censorship.tls_fetch.total_budget_ms == 0 {
+            return Err(ProxyError::Config(
+                "censorship.tls_fetch.total_budget_ms must be > 0".to_string(),
+            ));
+        }
+
         // Merge primary + extra TLS domains, deduplicate (primary always first).
         if !config.censorship.tls_domains.is_empty() {
             let mut all = Vec::with_capacity(1 + config.censorship.tls_domains.len());
@@ -860,7 +1048,7 @@ impl ProxyConfig {
         if !config.censorship.tls_emulation
             && config.censorship.fake_cert_len == default_fake_cert_len()
         {
-            config.censorship.fake_cert_len = rand::rng().gen_range(1024..4096);
+            config.censorship.fake_cert_len = rand::rng().random_range(1024..4096);
         }
 
         // Resolve listen_tcp: explicit value wins, otherwise auto-detect.
@@ -982,6 +1170,22 @@ impl ProxyConfig {
     }
 }
 
+#[cfg(test)]
+#[path = "tests/load_idle_policy_tests.rs"]
+mod load_idle_policy_tests;
+
+#[cfg(test)]
+#[path = "tests/load_security_tests.rs"]
+mod load_security_tests;
+
+#[cfg(test)]
+#[path = "tests/load_mask_shape_security_tests.rs"]
+mod load_mask_shape_security_tests;
+
+#[cfg(test)]
+#[path = "tests/load_mask_classifier_prefetch_timeout_security_tests.rs"]
+mod load_mask_classifier_prefetch_timeout_security_tests;
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1019,6 +1223,7 @@ mod tests {
             default_me_init_retry_attempts()
         );
         assert_eq!(cfg.general.me2dc_fallback, default_me2dc_fallback());
+        assert_eq!(cfg.general.me2dc_fast, default_me2dc_fast());
         assert_eq!(
             cfg.general.proxy_config_v4_cache_path,
             default_proxy_config_v4_cache_path()
@@ -1087,6 +1292,11 @@ mod tests {
         assert_eq!(cfg.general.update_every, default_update_every());
         assert_eq!(cfg.server.listen_addr_ipv4, default_listen_addr_ipv4());
         assert_eq!(cfg.server.listen_addr_ipv6, default_listen_addr_ipv6_opt());
+        assert_eq!(
+            cfg.server.proxy_protocol_trusted_cidrs,
+            default_proxy_protocol_trusted_cidrs()
+        );
+        assert_eq!(cfg.censorship.unknown_sni_action, UnknownSniAction::Drop);
         assert_eq!(cfg.server.api.listen, default_api_listen());
         assert_eq!(cfg.server.api.whitelist, default_api_whitelist());
         assert_eq!(
@@ -1153,6 +1363,7 @@ mod tests {
             default_me_init_retry_attempts()
         );
         assert_eq!(general.me2dc_fallback, default_me2dc_fallback());
+        assert_eq!(general.me2dc_fast, default_me2dc_fast());
         assert_eq!(
             general.proxy_config_v4_cache_path,
             default_proxy_config_v4_cache_path()
@@ -1219,6 +1430,14 @@ mod tests {
 
         let server = ServerConfig::default();
         assert_eq!(server.listen_addr_ipv6, Some(default_listen_addr_ipv6()));
+        assert_eq!(
+            server.proxy_protocol_trusted_cidrs,
+            default_proxy_protocol_trusted_cidrs()
+        );
+        assert_eq!(
+            AntiCensorshipConfig::default().unknown_sni_action,
+            UnknownSniAction::Drop
+        );
         assert_eq!(server.api.listen, default_api_listen());
         assert_eq!(server.api.whitelist, default_api_whitelist());
         assert_eq!(
@@ -1254,6 +1473,75 @@ mod tests {
         assert_eq!(access.users, default_access_users());
     }
 
+    #[test]
+    fn proxy_protocol_trusted_cidrs_missing_uses_trust_all_but_explicit_empty_stays_empty() {
+        let cfg_missing: ProxyConfig = toml::from_str(
+            r#"
+            [server]
+            [general]
+            [network]
+            [access]
+            "#,
+        )
+        .unwrap();
+        assert_eq!(
+            cfg_missing.server.proxy_protocol_trusted_cidrs,
+            default_proxy_protocol_trusted_cidrs()
+        );
+
+        let cfg_explicit_empty: ProxyConfig = toml::from_str(
+            r#"
+            [server]
+            proxy_protocol_trusted_cidrs = []
+
+            [general]
+            [network]
+            [access]
+            "#,
+        )
+        .unwrap();
+        assert!(
+            cfg_explicit_empty
+                .server
+                .proxy_protocol_trusted_cidrs
+                .is_empty()
+        );
+    }
+
+    #[test]
+    fn unknown_sni_action_parses_and_defaults_to_drop() {
+        let cfg_default: ProxyConfig = toml::from_str(
+            r#"
+            [server]
+            [general]
+            [network]
+            [access]
+            [censorship]
+            "#,
+        )
+        .unwrap();
+        assert_eq!(
+            cfg_default.censorship.unknown_sni_action,
+            UnknownSniAction::Drop
+        );
+
+        let cfg_mask: ProxyConfig = toml::from_str(
+            r#"
+            [server]
+            [general]
+            [network]
+            [access]
+            [censorship]
+            unknown_sni_action = "mask"
+            "#,
+        )
+        .unwrap();
+        assert_eq!(
+            cfg_mask.censorship.unknown_sni_action,
+            UnknownSniAction::Mask
+        );
+    }
+
     #[test]
     fn dc_overrides_allow_string_and_array() {
         let toml = r#"
@@ -1625,6 +1913,26 @@ mod tests {
         let _ = std::fs::remove_file(path);
     }
 
+    #[test]
+    fn tg_connect_zero_is_rejected() {
+        let toml = r#"
+            [timeouts]
+            tg_connect = 0
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_tg_connect_zero_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let err = ProxyConfig::load(&path).unwrap_err().to_string();
+        assert!(err.contains("timeouts.tg_connect must be > 0"));
+        let _ = std::fs::remove_file(path);
+    }
+
     #[test]
     fn rpc_proxy_req_every_out_of_range_is_rejected() {
         let toml = r#"
@@ -1697,7 +2005,9 @@ mod tests {
         let path = dir.join("telemt_me_route_backpressure_base_timeout_ms_out_of_range_test.toml");
         std::fs::write(&path, toml).unwrap();
         let err = ProxyConfig::load(&path).unwrap_err().to_string();
-        assert!(err.contains("general.me_route_backpressure_base_timeout_ms must be within [1, 5000]"));
+        assert!(
+            err.contains("general.me_route_backpressure_base_timeout_ms must be within [1, 5000]")
+        );
         let _ = std::fs::remove_file(path);
     }
 
@@ -1718,7 +2028,9 @@ mod tests {
         let path = dir.join("telemt_me_route_backpressure_high_timeout_ms_out_of_range_test.toml");
         std::fs::write(&path, toml).unwrap();
         let err = ProxyConfig::load(&path).unwrap_err().to_string();
-        assert!(err.contains("general.me_route_backpressure_high_timeout_ms must be within [1, 5000]"));
+        assert!(
+            err.contains("general.me_route_backpressure_high_timeout_ms must be within [1, 5000]")
+        );
         let _ = std::fs::remove_file(path);
     }
 
@@ -2197,6 +2509,94 @@ mod tests {
         let _ = std::fs::remove_file(path);
     }
 
+    #[test]
+    fn tls_fetch_defaults_are_applied() {
+        let toml = r#"
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_tls_fetch_defaults_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let cfg = ProxyConfig::load(&path).unwrap();
+        assert_eq!(
+            cfg.censorship.tls_fetch.profiles,
+            TlsFetchConfig::default().profiles
+        );
+        assert!(cfg.censorship.tls_fetch.strict_route);
+        assert_eq!(cfg.censorship.tls_fetch.attempt_timeout_ms, 5_000);
+        assert_eq!(cfg.censorship.tls_fetch.total_budget_ms, 15_000);
+        assert_eq!(cfg.censorship.tls_fetch.profile_cache_ttl_secs, 600);
+        let _ = std::fs::remove_file(path);
+    }
+
+    #[test]
+    fn tls_fetch_profiles_are_deduplicated_preserving_order() {
+        let toml = r#"
+            [censorship]
+            tls_domain = "example.com"
+            [censorship.tls_fetch]
+            profiles = ["compat_tls12", "modern_chrome_like", "compat_tls12", "legacy_minimal"]
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_tls_fetch_profiles_dedup_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let cfg = ProxyConfig::load(&path).unwrap();
+        assert_eq!(
+            cfg.censorship.tls_fetch.profiles,
+            vec![
+                TlsFetchProfile::CompatTls12,
+                TlsFetchProfile::ModernChromeLike,
+                TlsFetchProfile::LegacyMinimal
+            ]
+        );
+        let _ = std::fs::remove_file(path);
+    }
+
+    #[test]
+    fn tls_fetch_attempt_timeout_zero_is_rejected() {
+        let toml = r#"
+            [censorship]
+            tls_domain = "example.com"
+            [censorship.tls_fetch]
+            attempt_timeout_ms = 0
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_tls_fetch_attempt_timeout_zero_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let err = ProxyConfig::load(&path).unwrap_err().to_string();
+        assert!(err.contains("censorship.tls_fetch.attempt_timeout_ms must be > 0"));
+        let _ = std::fs::remove_file(path);
+    }
+
+    #[test]
+    fn tls_fetch_total_budget_zero_is_rejected() {
+        let toml = r#"
+            [censorship]
+            tls_domain = "example.com"
+            [censorship.tls_fetch]
+            total_budget_ms = 0
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_tls_fetch_total_budget_zero_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let err = ProxyConfig::load(&path).unwrap_err().to_string();
+        assert!(err.contains("censorship.tls_fetch.total_budget_ms must be > 0"));
+        let _ = std::fs::remove_file(path);
+    }
+
     #[test]
     fn invalid_ad_tag_is_disabled_during_load() {
         let toml = r#"

src/config/mod.rs

@@ -1,9 +1,9 @@
 //! Configuration.
 
 pub(crate) mod defaults;
-mod types;
-mod load;
 pub mod hot_reload;
+mod load;
+mod types;
 
 pub use load::ProxyConfig;
 pub use types::*;

src/config/tests/load_idle_policy_tests.rs

@@ -0,0 +1,80 @@
+use super::*;
+use std::fs;
+use std::path::PathBuf;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+fn write_temp_config(contents: &str) -> PathBuf {
+    let nonce = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .expect("system time must be after unix epoch")
+        .as_nanos();
+    let path = std::env::temp_dir().join(format!("telemt-idle-policy-{nonce}.toml"));
+    fs::write(&path, contents).expect("temp config write must succeed");
+    path
+}
+
+fn remove_temp_config(path: &PathBuf) {
+    let _ = fs::remove_file(path);
+}
+
+#[test]
+fn load_rejects_relay_hard_idle_smaller_than_soft_idle_with_clear_error() {
+    let path = write_temp_config(
+        r#"
+[timeouts]
+relay_client_idle_soft_secs = 120
+relay_client_idle_hard_secs = 60
+"#,
+    );
+
+    let err = ProxyConfig::load(&path).expect_err("config with hard<soft must fail");
+    let msg = err.to_string();
+    assert!(
+        msg.contains(
+            "timeouts.relay_client_idle_hard_secs must be >= timeouts.relay_client_idle_soft_secs"
+        ),
+        "error must explain the violated hard>=soft invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_relay_grace_larger_than_hard_idle_with_clear_error() {
+    let path = write_temp_config(
+        r#"
+[timeouts]
+relay_client_idle_soft_secs = 60
+relay_client_idle_hard_secs = 120
+relay_idle_grace_after_downstream_activity_secs = 121
+"#,
+    );
+
+    let err = ProxyConfig::load(&path).expect_err("config with grace>hard must fail");
+    let msg = err.to_string();
+    assert!(
+        msg.contains("timeouts.relay_idle_grace_after_downstream_activity_secs must be <= timeouts.relay_client_idle_hard_secs"),
+        "error must explain the violated grace<=hard invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_zero_handshake_timeout_with_clear_error() {
+    let path = write_temp_config(
+        r#"
+[timeouts]
+client_handshake = 0
+"#,
+    );
+
+    let err = ProxyConfig::load(&path).expect_err("config with zero handshake timeout must fail");
+    let msg = err.to_string();
+    assert!(
+        msg.contains("timeouts.client_handshake must be > 0"),
+        "error must explain that handshake timeout must be positive, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}

src/config/tests/load_mask_classifier_prefetch_timeout_security_tests.rs

@@ -0,0 +1,76 @@
+use super::*;
+use std::fs;
+use std::path::PathBuf;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+fn write_temp_config(contents: &str) -> PathBuf {
+    let nonce = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .expect("system time must be after unix epoch")
+        .as_nanos();
+    let path = std::env::temp_dir().join(format!(
+        "telemt-load-mask-prefetch-timeout-security-{nonce}.toml"
+    ));
+    fs::write(&path, contents).expect("temp config write must succeed");
+    path
+}
+
+fn remove_temp_config(path: &PathBuf) {
+    let _ = fs::remove_file(path);
+}
+
+#[test]
+fn load_rejects_mask_classifier_prefetch_timeout_below_min_bound() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_classifier_prefetch_timeout_ms = 4
+"#,
+    );
+
+    let err = ProxyConfig::load(&path)
+        .expect_err("prefetch timeout below minimum security bound must be rejected");
+    let msg = err.to_string();
+    assert!(
+        msg.contains("censorship.mask_classifier_prefetch_timeout_ms must be within [5, 50]"),
+        "error must explain timeout bound invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_mask_classifier_prefetch_timeout_above_max_bound() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_classifier_prefetch_timeout_ms = 51
+"#,
+    );
+
+    let err = ProxyConfig::load(&path)
+        .expect_err("prefetch timeout above max security bound must be rejected");
+    let msg = err.to_string();
+    assert!(
+        msg.contains("censorship.mask_classifier_prefetch_timeout_ms must be within [5, 50]"),
+        "error must explain timeout bound invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_accepts_mask_classifier_prefetch_timeout_within_bounds() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_classifier_prefetch_timeout_ms = 20
+"#,
+    );
+
+    let cfg =
+        ProxyConfig::load(&path).expect("prefetch timeout within security bounds must be accepted");
+    assert_eq!(cfg.censorship.mask_classifier_prefetch_timeout_ms, 20);
+
+    remove_temp_config(&path);
+}

src/config/tests/load_mask_shape_security_tests.rs

@@ -0,0 +1,292 @@
+use super::*;
+use std::fs;
+use std::path::PathBuf;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+fn write_temp_config(contents: &str) -> PathBuf {
+    let nonce = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .expect("system time must be after unix epoch")
+        .as_nanos();
+    let path = std::env::temp_dir().join(format!("telemt-load-mask-shape-security-{nonce}.toml"));
+    fs::write(&path, contents).expect("temp config write must succeed");
+    path
+}
+
+fn remove_temp_config(path: &PathBuf) {
+    let _ = fs::remove_file(path);
+}
+
+#[test]
+fn load_rejects_zero_mask_shape_bucket_floor_bytes() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_shape_bucket_floor_bytes = 0
+mask_shape_bucket_cap_bytes = 4096
+"#,
+    );
+
+    let err =
+        ProxyConfig::load(&path).expect_err("zero mask_shape_bucket_floor_bytes must be rejected");
+    let msg = err.to_string();
+    assert!(
+        msg.contains("censorship.mask_shape_bucket_floor_bytes must be > 0"),
+        "error must explain floor>0 invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_mask_shape_bucket_cap_less_than_floor() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_shape_bucket_floor_bytes = 1024
+mask_shape_bucket_cap_bytes = 512
+"#,
+    );
+
+    let err =
+        ProxyConfig::load(&path).expect_err("mask_shape_bucket_cap_bytes < floor must be rejected");
+    let msg = err.to_string();
+    assert!(
+        msg.contains(
+            "censorship.mask_shape_bucket_cap_bytes must be >= censorship.mask_shape_bucket_floor_bytes"
+        ),
+        "error must explain cap>=floor invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_accepts_mask_shape_bucket_cap_equal_to_floor() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_shape_hardening = true
+mask_shape_bucket_floor_bytes = 1024
+mask_shape_bucket_cap_bytes = 1024
+"#,
+    );
+
+    let cfg = ProxyConfig::load(&path).expect("equal cap and floor must be accepted");
+    assert!(cfg.censorship.mask_shape_hardening);
+    assert_eq!(cfg.censorship.mask_shape_bucket_floor_bytes, 1024);
+    assert_eq!(cfg.censorship.mask_shape_bucket_cap_bytes, 1024);
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_above_cap_blur_when_shape_hardening_disabled() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_shape_hardening = false
+mask_shape_above_cap_blur = true
+mask_shape_above_cap_blur_max_bytes = 64
+"#,
+    );
+
+    let err =
+        ProxyConfig::load(&path).expect_err("above-cap blur must require shape hardening enabled");
+    let msg = err.to_string();
+    assert!(
+        msg.contains(
+            "censorship.mask_shape_above_cap_blur requires censorship.mask_shape_hardening = true"
+        ),
+        "error must explain blur prerequisite, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_above_cap_blur_with_zero_max_bytes() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_shape_hardening = true
+mask_shape_above_cap_blur = true
+mask_shape_above_cap_blur_max_bytes = 0
+"#,
+    );
+
+    let err =
+        ProxyConfig::load(&path).expect_err("above-cap blur max bytes must be > 0 when enabled");
+    let msg = err.to_string();
+    assert!(
+        msg.contains("censorship.mask_shape_above_cap_blur_max_bytes must be > 0 when censorship.mask_shape_above_cap_blur is enabled"),
+        "error must explain blur max bytes invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_timing_normalization_floor_zero_when_enabled() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_timing_normalization_enabled = true
+mask_timing_normalization_floor_ms = 0
+mask_timing_normalization_ceiling_ms = 200
+"#,
+    );
+
+    let err =
+        ProxyConfig::load(&path).expect_err("timing normalization floor must be > 0 when enabled");
+    let msg = err.to_string();
+    assert!(
+        msg.contains("censorship.mask_timing_normalization_floor_ms must be > 0 when censorship.mask_timing_normalization_enabled is true"),
+        "error must explain timing floor invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_timing_normalization_ceiling_below_floor() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_timing_normalization_enabled = true
+mask_timing_normalization_floor_ms = 220
+mask_timing_normalization_ceiling_ms = 200
+"#,
+    );
+
+    let err = ProxyConfig::load(&path).expect_err("timing normalization ceiling must be >= floor");
+    let msg = err.to_string();
+    assert!(
+        msg.contains("censorship.mask_timing_normalization_ceiling_ms must be >= censorship.mask_timing_normalization_floor_ms"),
+        "error must explain timing ceiling/floor invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_accepts_valid_timing_normalization_and_above_cap_blur_config() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_shape_hardening = true
+mask_shape_above_cap_blur = true
+mask_shape_above_cap_blur_max_bytes = 128
+mask_timing_normalization_enabled = true
+mask_timing_normalization_floor_ms = 150
+mask_timing_normalization_ceiling_ms = 240
+"#,
+    );
+
+    let cfg = ProxyConfig::load(&path)
+        .expect("valid blur and timing normalization settings must be accepted");
+    assert!(cfg.censorship.mask_shape_hardening);
+    assert!(cfg.censorship.mask_shape_above_cap_blur);
+    assert_eq!(cfg.censorship.mask_shape_above_cap_blur_max_bytes, 128);
+    assert!(cfg.censorship.mask_timing_normalization_enabled);
+    assert_eq!(cfg.censorship.mask_timing_normalization_floor_ms, 150);
+    assert_eq!(cfg.censorship.mask_timing_normalization_ceiling_ms, 240);
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_aggressive_shape_mode_when_shape_hardening_disabled() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_shape_hardening = false
+mask_shape_hardening_aggressive_mode = true
+"#,
+    );
+
+    let err = ProxyConfig::load(&path)
+        .expect_err("aggressive shape hardening mode must require shape hardening enabled");
+    let msg = err.to_string();
+    assert!(
+        msg.contains("censorship.mask_shape_hardening_aggressive_mode requires censorship.mask_shape_hardening = true"),
+        "error must explain aggressive-mode prerequisite, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_accepts_aggressive_shape_mode_when_shape_hardening_enabled() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_shape_hardening = true
+mask_shape_hardening_aggressive_mode = true
+mask_shape_above_cap_blur = true
+mask_shape_above_cap_blur_max_bytes = 8
+"#,
+    );
+
+    let cfg = ProxyConfig::load(&path)
+        .expect("aggressive shape hardening mode should be accepted when prerequisites are met");
+    assert!(cfg.censorship.mask_shape_hardening);
+    assert!(cfg.censorship.mask_shape_hardening_aggressive_mode);
+    assert!(cfg.censorship.mask_shape_above_cap_blur);
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_zero_mask_relay_max_bytes() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_relay_max_bytes = 0
+"#,
+    );
+
+    let err = ProxyConfig::load(&path).expect_err("mask_relay_max_bytes must be > 0");
+    let msg = err.to_string();
+    assert!(
+        msg.contains("censorship.mask_relay_max_bytes must be > 0"),
+        "error must explain non-zero relay cap invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_mask_relay_max_bytes_above_upper_bound() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_relay_max_bytes = 67108865
+"#,
+    );
+
+    let err =
+        ProxyConfig::load(&path).expect_err("mask_relay_max_bytes above hard cap must be rejected");
+    let msg = err.to_string();
+    assert!(
+        msg.contains("censorship.mask_relay_max_bytes must be <= 67108864"),
+        "error must explain relay cap upper bound invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_accepts_valid_mask_relay_max_bytes() {
+    let path = write_temp_config(
+        r#"
+[censorship]
+mask_relay_max_bytes = 8388608
+"#,
+    );
+
+    let cfg = ProxyConfig::load(&path).expect("valid mask_relay_max_bytes must be accepted");
+    assert_eq!(cfg.censorship.mask_relay_max_bytes, 8_388_608);
+
+    remove_temp_config(&path);
+}

src/config/tests/load_security_tests.rs

@@ -0,0 +1,88 @@
+use super::*;
+use std::fs;
+use std::path::PathBuf;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+fn write_temp_config(contents: &str) -> PathBuf {
+    let nonce = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .expect("system time must be after unix epoch")
+        .as_nanos();
+    let path = std::env::temp_dir().join(format!("telemt-load-security-{nonce}.toml"));
+    fs::write(&path, contents).expect("temp config write must succeed");
+    path
+}
+
+fn remove_temp_config(path: &PathBuf) {
+    let _ = fs::remove_file(path);
+}
+
+#[test]
+fn load_rejects_server_hello_delay_equal_to_handshake_timeout_budget() {
+    let path = write_temp_config(
+        r#"
+[timeouts]
+client_handshake = 1
+
+[censorship]
+server_hello_delay_max_ms = 1000
+"#,
+    );
+
+    let err =
+        ProxyConfig::load(&path).expect_err("delay equal to handshake timeout must be rejected");
+    let msg = err.to_string();
+    assert!(
+        msg.contains(
+            "censorship.server_hello_delay_max_ms must be < timeouts.client_handshake * 1000"
+        ),
+        "error must explain delay<timeout invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_rejects_server_hello_delay_larger_than_handshake_timeout_budget() {
+    let path = write_temp_config(
+        r#"
+[timeouts]
+client_handshake = 1
+
+[censorship]
+server_hello_delay_max_ms = 1500
+"#,
+    );
+
+    let err =
+        ProxyConfig::load(&path).expect_err("delay larger than handshake timeout must be rejected");
+    let msg = err.to_string();
+    assert!(
+        msg.contains(
+            "censorship.server_hello_delay_max_ms must be < timeouts.client_handshake * 1000"
+        ),
+        "error must explain delay<timeout invariant, got: {msg}"
+    );
+
+    remove_temp_config(&path);
+}
+
+#[test]
+fn load_accepts_server_hello_delay_strictly_below_handshake_timeout_budget() {
+    let path = write_temp_config(
+        r#"
+[timeouts]
+client_handshake = 1
+
+[censorship]
+server_hello_delay_max_ms = 999
+"#,
+    );
+
+    let cfg =
+        ProxyConfig::load(&path).expect("delay below handshake timeout budget must be accepted");
+    assert_eq!(cfg.timeouts.client_handshake, 1);
+    assert_eq!(cfg.censorship.server_hello_delay_max_ms, 999);
+
+    remove_temp_config(&path);
+}

src/config/types.rs

@@ -429,6 +429,11 @@ pub struct GeneralConfig {
     #[serde(default = "default_me2dc_fallback")]
     pub me2dc_fallback: bool,
 
+    /// Fast ME->Direct fallback mode for new sessions.
+    /// Active only when both `use_middle_proxy=true` and `me2dc_fallback=true`.
+    #[serde(default = "default_me2dc_fast")]
+    pub me2dc_fast: bool,
+
     /// Enable ME keepalive padding frames.
     #[serde(default = "default_true")]
     pub me_keepalive_enabled: bool,
@@ -468,7 +473,7 @@ pub struct GeneralConfig {
     pub me_c2me_send_timeout_ms: u64,
 
     /// Bounded wait in milliseconds for routing ME DATA to per-connection queue.
-    /// `0` keeps legacy no-wait behavior.
+    /// `0` keeps non-blocking routing; values >0 enable bounded wait for compatibility.
     #[serde(default = "default_me_reader_route_data_wait_ms")]
     pub me_reader_route_data_wait_ms: u64,
 
@@ -489,6 +494,14 @@ pub struct GeneralConfig {
     #[serde(default = "default_me_d2c_ack_flush_immediate")]
     pub me_d2c_ack_flush_immediate: bool,
 
+    /// Additional bytes above strict per-user quota allowed in hot-path soft mode.
+    #[serde(default = "default_me_quota_soft_overshoot_bytes")]
+    pub me_quota_soft_overshoot_bytes: u64,
+
+    /// Shrink threshold for reusable ME->Client frame assembly buffer.
+    #[serde(default = "default_me_d2c_frame_buf_shrink_threshold_bytes")]
+    pub me_d2c_frame_buf_shrink_threshold_bytes: usize,
+
     /// Copy buffer size for client->DC direction in direct relay.
     #[serde(default = "default_direct_relay_copy_buf_c2s_bytes")]
     pub direct_relay_copy_buf_c2s_bytes: usize,
@@ -931,6 +944,7 @@ impl Default for GeneralConfig {
             middle_proxy_warm_standby: default_middle_proxy_warm_standby(),
             me_init_retry_attempts: default_me_init_retry_attempts(),
             me2dc_fallback: default_me2dc_fallback(),
+            me2dc_fast: default_me2dc_fast(),
             me_keepalive_enabled: default_true(),
             me_keepalive_interval_secs: default_keepalive_interval(),
             me_keepalive_jitter_secs: default_keepalive_jitter(),
@@ -945,6 +959,9 @@ impl Default for GeneralConfig {
             me_d2c_flush_batch_max_bytes: default_me_d2c_flush_batch_max_bytes(),
             me_d2c_flush_batch_max_delay_us: default_me_d2c_flush_batch_max_delay_us(),
             me_d2c_ack_flush_immediate: default_me_d2c_ack_flush_immediate(),
+            me_quota_soft_overshoot_bytes: default_me_quota_soft_overshoot_bytes(),
+            me_d2c_frame_buf_shrink_threshold_bytes:
+                default_me_d2c_frame_buf_shrink_threshold_bytes(),
             direct_relay_copy_buf_c2s_bytes: default_direct_relay_copy_buf_c2s_bytes(),
             direct_relay_copy_buf_s2c_bytes: default_direct_relay_copy_buf_s2c_bytes(),
             me_warmup_stagger_enabled: default_true(),
@@ -1047,8 +1064,7 @@ impl Default for GeneralConfig {
             me_pool_drain_soft_evict_per_writer: default_me_pool_drain_soft_evict_per_writer(),
             me_pool_drain_soft_evict_budget_per_core:
                 default_me_pool_drain_soft_evict_budget_per_core(),
-            me_pool_drain_soft_evict_cooldown_ms:
-                default_me_pool_drain_soft_evict_cooldown_ms(),
+            me_pool_drain_soft_evict_cooldown_ms: default_me_pool_drain_soft_evict_cooldown_ms(),
             me_bind_stale_mode: MeBindStaleMode::default(),
             me_bind_stale_ttl_secs: default_me_bind_stale_ttl_secs(),
             me_pool_min_fresh_ratio: default_me_pool_min_fresh_ratio(),
@@ -1228,6 +1244,14 @@ pub struct ServerConfig {
     #[serde(default = "default_proxy_protocol_header_timeout_ms")]
     pub proxy_protocol_header_timeout_ms: u64,
 
+    /// Trusted source CIDRs allowed to send incoming PROXY protocol headers.
+    ///
+    /// If this field is omitted in config, it defaults to trust-all CIDRs
+    /// (`0.0.0.0/0` and `::/0`). If it is explicitly set to an empty list,
+    /// all PROXY protocol headers are rejected.
+    #[serde(default = "default_proxy_protocol_trusted_cidrs")]
+    pub proxy_protocol_trusted_cidrs: Vec<IpNetwork>,
+
     /// Port for the Prometheus-compatible metrics endpoint.
     /// Enables metrics when set; binds on all interfaces (dual-stack) by default.
     #[serde(default)]
@@ -1270,6 +1294,7 @@ impl Default for ServerConfig {
             listen_tcp: None,
             proxy_protocol: false,
             proxy_protocol_header_timeout_ms: default_proxy_protocol_header_timeout_ms(),
+            proxy_protocol_trusted_cidrs: default_proxy_protocol_trusted_cidrs(),
             metrics_port: None,
             metrics_listen: None,
             metrics_whitelist: default_metrics_whitelist(),
@@ -1286,6 +1311,24 @@ pub struct TimeoutsConfig {
     #[serde(default = "default_handshake_timeout")]
     pub client_handshake: u64,
 
+    /// Enables soft/hard relay client idle policy for middle-relay sessions.
+    #[serde(default = "default_relay_idle_policy_v2_enabled")]
+    pub relay_idle_policy_v2_enabled: bool,
+
+    /// Soft idle threshold for middle-relay client uplink activity in seconds.
+    /// Hitting this threshold marks the session as idle-candidate, but does not close it.
+    #[serde(default = "default_relay_client_idle_soft_secs")]
+    pub relay_client_idle_soft_secs: u64,
+
+    /// Hard idle threshold for middle-relay client uplink activity in seconds.
+    /// Hitting this threshold closes the session.
+    #[serde(default = "default_relay_client_idle_hard_secs")]
+    pub relay_client_idle_hard_secs: u64,
+
+    /// Additional grace in seconds added to hard idle window after recent downstream activity.
+    #[serde(default = "default_relay_idle_grace_after_downstream_activity_secs")]
+    pub relay_idle_grace_after_downstream_activity_secs: u64,
+
     #[serde(default = "default_connect_timeout")]
     pub tg_connect: u64,
 
@@ -1308,6 +1351,11 @@ impl Default for TimeoutsConfig {
     fn default() -> Self {
         Self {
             client_handshake: default_handshake_timeout(),
+            relay_idle_policy_v2_enabled: default_relay_idle_policy_v2_enabled(),
+            relay_client_idle_soft_secs: default_relay_client_idle_soft_secs(),
+            relay_client_idle_hard_secs: default_relay_client_idle_hard_secs(),
+            relay_idle_grace_after_downstream_activity_secs:
+                default_relay_idle_grace_after_downstream_activity_secs(),
             tg_connect: default_connect_timeout(),
             client_keepalive: default_keepalive(),
             client_ack: default_ack_timeout(),
@@ -1317,6 +1365,90 @@ impl Default for TimeoutsConfig {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "lowercase")]
+pub enum UnknownSniAction {
+    #[default]
+    Drop,
+    Mask,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum TlsFetchProfile {
+    ModernChromeLike,
+    ModernFirefoxLike,
+    CompatTls12,
+    LegacyMinimal,
+}
+
+impl TlsFetchProfile {
+    pub fn as_str(self) -> &'static str {
+        match self {
+            TlsFetchProfile::ModernChromeLike => "modern_chrome_like",
+            TlsFetchProfile::ModernFirefoxLike => "modern_firefox_like",
+            TlsFetchProfile::CompatTls12 => "compat_tls12",
+            TlsFetchProfile::LegacyMinimal => "legacy_minimal",
+        }
+    }
+}
+
+fn default_tls_fetch_profiles() -> Vec<TlsFetchProfile> {
+    vec![
+        TlsFetchProfile::ModernChromeLike,
+        TlsFetchProfile::ModernFirefoxLike,
+        TlsFetchProfile::CompatTls12,
+        TlsFetchProfile::LegacyMinimal,
+    ]
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct TlsFetchConfig {
+    /// Ordered list of ClientHello profiles used for adaptive fallback.
+    #[serde(default = "default_tls_fetch_profiles")]
+    pub profiles: Vec<TlsFetchProfile>,
+
+    /// When true and upstream route is configured, TLS fetch fails closed on
+    /// upstream connect errors and does not fallback to direct TCP.
+    #[serde(default = "default_tls_fetch_strict_route")]
+    pub strict_route: bool,
+
+    /// Timeout per one profile attempt in milliseconds.
+    #[serde(default = "default_tls_fetch_attempt_timeout_ms")]
+    pub attempt_timeout_ms: u64,
+
+    /// Total wall-clock budget in milliseconds across all profile attempts.
+    #[serde(default = "default_tls_fetch_total_budget_ms")]
+    pub total_budget_ms: u64,
+
+    /// Adds GREASE-style values into selected ClientHello extensions.
+    #[serde(default)]
+    pub grease_enabled: bool,
+
+    /// Produces deterministic ClientHello randomness for debugging/tests.
+    #[serde(default)]
+    pub deterministic: bool,
+
+    /// TTL for winner-profile cache entries in seconds.
+    /// Set to 0 to disable profile cache.
+    #[serde(default = "default_tls_fetch_profile_cache_ttl_secs")]
+    pub profile_cache_ttl_secs: u64,
+}
+
+impl Default for TlsFetchConfig {
+    fn default() -> Self {
+        Self {
+            profiles: default_tls_fetch_profiles(),
+            strict_route: default_tls_fetch_strict_route(),
+            attempt_timeout_ms: default_tls_fetch_attempt_timeout_ms(),
+            total_budget_ms: default_tls_fetch_total_budget_ms(),
+            grease_enabled: false,
+            deterministic: false,
+            profile_cache_ttl_secs: default_tls_fetch_profile_cache_ttl_secs(),
+        }
+    }
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct AntiCensorshipConfig {
     #[serde(default = "default_tls_domain")]
@@ -1326,11 +1458,19 @@ pub struct AntiCensorshipConfig {
     #[serde(default)]
     pub tls_domains: Vec<String>,
 
+    /// Policy for TLS ClientHello with unknown (non-configured) SNI.
+    #[serde(default)]
+    pub unknown_sni_action: UnknownSniAction,
+
     /// Upstream scope used for TLS front metadata fetches.
     /// Empty value keeps default upstream routing behavior.
     #[serde(default = "default_tls_fetch_scope")]
     pub tls_fetch_scope: String,
 
+    /// Fetch strategy for TLS front metadata bootstrap and periodic refresh.
+    #[serde(default)]
+    pub tls_fetch: TlsFetchConfig,
+
     #[serde(default = "default_true")]
     pub mask: bool,
 
@@ -1381,6 +1521,54 @@ pub struct AntiCensorshipConfig {
     /// Allows the backend to see the real client IP.
     #[serde(default)]
     pub mask_proxy_protocol: u8,
+
+    /// Enable shape-channel hardening on mask backend path by padding
+    /// client->mask stream tail to configured buckets on stream end.
+    #[serde(default = "default_mask_shape_hardening")]
+    pub mask_shape_hardening: bool,
+
+    /// Opt-in aggressive shape hardening mode.
+    /// When enabled, masking may shape some backend-silent timeout paths and
+    /// enforces strictly positive above-cap blur when blur is enabled.
+    #[serde(default = "default_mask_shape_hardening_aggressive_mode")]
+    pub mask_shape_hardening_aggressive_mode: bool,
+
+    /// Minimum bucket size for mask shape hardening padding.
+    #[serde(default = "default_mask_shape_bucket_floor_bytes")]
+    pub mask_shape_bucket_floor_bytes: usize,
+
+    /// Maximum bucket size for mask shape hardening padding.
+    #[serde(default = "default_mask_shape_bucket_cap_bytes")]
+    pub mask_shape_bucket_cap_bytes: usize,
+
+    /// Add bounded random tail bytes even when total bytes already exceed
+    /// mask_shape_bucket_cap_bytes.
+    #[serde(default = "default_mask_shape_above_cap_blur")]
+    pub mask_shape_above_cap_blur: bool,
+
+    /// Maximum random bytes appended above cap when above-cap blur is enabled.
+    #[serde(default = "default_mask_shape_above_cap_blur_max_bytes")]
+    pub mask_shape_above_cap_blur_max_bytes: usize,
+
+    /// Maximum bytes relayed per direction on unauthenticated masking fallback paths.
+    #[serde(default = "default_mask_relay_max_bytes")]
+    pub mask_relay_max_bytes: usize,
+
+    /// Prefetch timeout (ms) for extending fragmented masking classifier window.
+    #[serde(default = "default_mask_classifier_prefetch_timeout_ms")]
+    pub mask_classifier_prefetch_timeout_ms: u64,
+
+    /// Enable outcome-time normalization envelope for masking fallback.
+    #[serde(default = "default_mask_timing_normalization_enabled")]
+    pub mask_timing_normalization_enabled: bool,
+
+    /// Lower bound (ms) for masking outcome timing envelope.
+    #[serde(default = "default_mask_timing_normalization_floor_ms")]
+    pub mask_timing_normalization_floor_ms: u64,
+
+    /// Upper bound (ms) for masking outcome timing envelope.
+    #[serde(default = "default_mask_timing_normalization_ceiling_ms")]
+    pub mask_timing_normalization_ceiling_ms: u64,
 }
 
 impl Default for AntiCensorshipConfig {
@@ -1388,7 +1576,9 @@ impl Default for AntiCensorshipConfig {
         Self {
             tls_domain: default_tls_domain(),
             tls_domains: Vec::new(),
+            unknown_sni_action: UnknownSniAction::Drop,
             tls_fetch_scope: default_tls_fetch_scope(),
+            tls_fetch: TlsFetchConfig::default(),
             mask: default_true(),
             mask_host: None,
             mask_port: default_mask_port(),
@@ -1402,6 +1592,17 @@ impl Default for AntiCensorshipConfig {
             tls_full_cert_ttl_secs: default_tls_full_cert_ttl_secs(),
             alpn_enforce: default_alpn_enforce(),
             mask_proxy_protocol: 0,
+            mask_shape_hardening: default_mask_shape_hardening(),
+            mask_shape_hardening_aggressive_mode: default_mask_shape_hardening_aggressive_mode(),
+            mask_shape_bucket_floor_bytes: default_mask_shape_bucket_floor_bytes(),
+            mask_shape_bucket_cap_bytes: default_mask_shape_bucket_cap_bytes(),
+            mask_shape_above_cap_blur: default_mask_shape_above_cap_blur(),
+            mask_shape_above_cap_blur_max_bytes: default_mask_shape_above_cap_blur_max_bytes(),
+            mask_relay_max_bytes: default_mask_relay_max_bytes(),
+            mask_classifier_prefetch_timeout_ms: default_mask_classifier_prefetch_timeout_ms(),
+            mask_timing_normalization_enabled: default_mask_timing_normalization_enabled(),
+            mask_timing_normalization_floor_ms: default_mask_timing_normalization_floor_ms(),
+            mask_timing_normalization_ceiling_ms: default_mask_timing_normalization_ceiling_ms(),
         }
     }
 }

src/crypto/aes.rs

@@ -13,10 +13,13 @@
 
 #![allow(dead_code)]
 
-use aes::Aes256;
-use ctr::{Ctr128BE, cipher::{KeyIvInit, StreamCipher}};
-use zeroize::Zeroize;
 use crate::error::{ProxyError, Result};
+use aes::Aes256;
+use ctr::{
+    Ctr128BE,
+    cipher::{KeyIvInit, StreamCipher},
+};
+use zeroize::Zeroize;
 
 type Aes256Ctr = Ctr128BE<Aes256>;
 
@@ -46,10 +49,16 @@ impl AesCtr {
     /// Create from key and IV slices
     pub fn from_key_iv(key: &[u8], iv: &[u8]) -> Result<Self> {
         if key.len() != 32 {
-            return Err(ProxyError::InvalidKeyLength { expected: 32, got: key.len() });
+            return Err(ProxyError::InvalidKeyLength {
+                expected: 32,
+                got: key.len(),
+            });
         }
         if iv.len() != 16 {
-            return Err(ProxyError::InvalidKeyLength { expected: 16, got: iv.len() });
+            return Err(ProxyError::InvalidKeyLength {
+                expected: 16,
+                got: iv.len(),
+            });
         }
 
         let key: [u8; 32] = key.try_into().unwrap();
@@ -108,10 +117,16 @@ impl AesCbc {
     /// Create from slices
     pub fn from_slices(key: &[u8], iv: &[u8]) -> Result<Self> {
         if key.len() != 32 {
-            return Err(ProxyError::InvalidKeyLength { expected: 32, got: key.len() });
+            return Err(ProxyError::InvalidKeyLength {
+                expected: 32,
+                got: key.len(),
+            });
         }
         if iv.len() != 16 {
-            return Err(ProxyError::InvalidKeyLength { expected: 16, got: iv.len() });
+            return Err(ProxyError::InvalidKeyLength {
+                expected: 16,
+                got: iv.len(),
+            });
         }
 
         Ok(Self {
@@ -150,9 +165,10 @@ impl AesCbc {
     /// CBC Encryption: C[i] = AES_Encrypt(P[i] XOR C[i-1]), where C[-1] = IV
     pub fn encrypt(&self, data: &[u8]) -> Result<Vec<u8>> {
         if !data.len().is_multiple_of(Self::BLOCK_SIZE) {
-            return Err(ProxyError::Crypto(
-                format!("CBC data must be aligned to 16 bytes, got {}", data.len())
-            ));
+            return Err(ProxyError::Crypto(format!(
+                "CBC data must be aligned to 16 bytes, got {}",
+                data.len()
+            )));
         }
 
         if data.is_empty() {
@@ -181,9 +197,10 @@ impl AesCbc {
     /// CBC Decryption: P[i] = AES_Decrypt(C[i]) XOR C[i-1], where C[-1] = IV
     pub fn decrypt(&self, data: &[u8]) -> Result<Vec<u8>> {
         if !data.len().is_multiple_of(Self::BLOCK_SIZE) {
-            return Err(ProxyError::Crypto(
-                format!("CBC data must be aligned to 16 bytes, got {}", data.len())
-            ));
+            return Err(ProxyError::Crypto(format!(
+                "CBC data must be aligned to 16 bytes, got {}",
+                data.len()
+            )));
         }
 
         if data.is_empty() {
@@ -210,9 +227,10 @@ impl AesCbc {
     /// Encrypt data in-place
     pub fn encrypt_in_place(&self, data: &mut [u8]) -> Result<()> {
         if !data.len().is_multiple_of(Self::BLOCK_SIZE) {
-            return Err(ProxyError::Crypto(
-                format!("CBC data must be aligned to 16 bytes, got {}", data.len())
-            ));
+            return Err(ProxyError::Crypto(format!(
+                "CBC data must be aligned to 16 bytes, got {}",
+                data.len()
+            )));
         }
 
         if data.is_empty() {
@@ -243,9 +261,10 @@ impl AesCbc {
     /// Decrypt data in-place
     pub fn decrypt_in_place(&self, data: &mut [u8]) -> Result<()> {
         if !data.len().is_multiple_of(Self::BLOCK_SIZE) {
-            return Err(ProxyError::Crypto(
-                format!("CBC data must be aligned to 16 bytes, got {}", data.len())
-            ));
+            return Err(ProxyError::Crypto(format!(
+                "CBC data must be aligned to 16 bytes, got {}",
+                data.len()
+            )));
         }
 
         if data.is_empty() {

src/crypto/hash.rs

@@ -12,10 +12,10 @@
 //! usages are intentional and protocol-mandated.
 
 use hmac::{Hmac, Mac};
-use sha2::Sha256;
 use md5::Md5;
 use sha1::Sha1;
 use sha2::Digest;
+use sha2::Sha256;
 
 type HmacSha256 = Hmac<Sha256>;
 
@@ -28,8 +28,7 @@ pub fn sha256(data: &[u8]) -> [u8; 32] {
 
 /// SHA-256 HMAC
 pub fn sha256_hmac(key: &[u8], data: &[u8]) -> [u8; 32] {
-    let mut mac = HmacSha256::new_from_slice(key)
-        .expect("HMAC accepts any key length");
+    let mut mac = HmacSha256::new_from_slice(key).expect("HMAC accepts any key length");
     mac.update(data);
     mac.finalize().into_bytes().into()
 }
@@ -124,17 +123,8 @@ pub fn derive_middleproxy_keys(
     srv_ipv6: Option<&[u8; 16]>,
 ) -> ([u8; 32], [u8; 16]) {
     let s = build_middleproxy_prekey(
-        nonce_srv,
-        nonce_clt,
-        clt_ts,
-        srv_ip,
-        clt_port,
-        purpose,
-        clt_ip,
-        srv_port,
-        secret,
-        clt_ipv6,
-        srv_ipv6,
+        nonce_srv, nonce_clt, clt_ts, srv_ip, clt_port, purpose, clt_ip, srv_port, secret,
+        clt_ipv6, srv_ipv6,
     );
 
     let md5_1 = md5(&s[1..]);
@@ -164,17 +154,8 @@ mod tests {
         let secret = vec![0x55u8; 128];
 
         let prekey = build_middleproxy_prekey(
-            &nonce_srv,
-            &nonce_clt,
-            &clt_ts,
-            srv_ip,
-            &clt_port,
-            b"CLIENT",
-            clt_ip,
-            &srv_port,
-            &secret,
-            None,
-            None,
+            &nonce_srv, &nonce_clt, &clt_ts, srv_ip, &clt_port, b"CLIENT", clt_ip, &srv_port,
+            &secret, None, None,
         );
         let digest = sha256(&prekey);
         assert_eq!(

src/crypto/mod.rs

@@ -4,7 +4,7 @@ pub mod aes;
 pub mod hash;
 pub mod random;
 
-pub use aes::{AesCtr, AesCbc};
+pub use aes::{AesCbc, AesCtr};
 pub use hash::{
     build_middleproxy_prekey, crc32, crc32c, derive_middleproxy_keys, sha256, sha256_hmac,
 };

src/crypto/random.rs

@@ -3,11 +3,11 @@
 #![allow(deprecated)]
 #![allow(dead_code)]
 
-use rand::{Rng, RngCore, SeedableRng};
-use rand::rngs::StdRng;
-use parking_lot::Mutex;
-use zeroize::Zeroize;
 use crate::crypto::AesCtr;
+use parking_lot::Mutex;
+use rand::rngs::StdRng;
+use rand::{Rng, RngExt, SeedableRng};
+use zeroize::Zeroize;
 
 /// Cryptographically secure PRNG with AES-CTR
 pub struct SecureRandom {
@@ -101,7 +101,7 @@ impl SecureRandom {
             return 0;
         }
         let mut inner = self.inner.lock();
-        inner.rng.gen_range(0..max)
+        inner.rng.random_range(0..max)
     }
 
     /// Generate random bits
@@ -141,7 +141,7 @@ impl SecureRandom {
     pub fn shuffle<T>(&self, slice: &mut [T]) {
         let mut inner = self.inner.lock();
         for i in (1..slice.len()).rev() {
-            let j = inner.rng.gen_range(0..=i);
+            let j = inner.rng.random_range(0..=i);
             slice.swap(i, j);
         }
     }

src/error.rs

@@ -12,28 +12,15 @@ use thiserror::Error;
 #[derive(Debug)]
 pub enum StreamError {
     /// Partial read: got fewer bytes than expected
-    PartialRead {
-        expected: usize,
-        got: usize,
-    },
+    PartialRead { expected: usize, got: usize },
     /// Partial write: wrote fewer bytes than expected
-    PartialWrite {
-        expected: usize,
-        written: usize,
-    },
+    PartialWrite { expected: usize, written: usize },
     /// Stream is in poisoned state and cannot be used
-    Poisoned {
-        reason: String,
-    },
+    Poisoned { reason: String },
     /// Buffer overflow: attempted to buffer more than allowed
-    BufferOverflow {
-        limit: usize,
-        attempted: usize,
-    },
+    BufferOverflow { limit: usize, attempted: usize },
     /// Invalid frame format
-    InvalidFrame {
-        details: String,
-    },
+    InvalidFrame { details: String },
     /// Unexpected end of stream
     UnexpectedEof,
     /// Underlying I/O error
@@ -47,13 +34,21 @@ impl fmt::Display for StreamError {
                 write!(f, "partial read: expected {} bytes, got {}", expected, got)
             }
             Self::PartialWrite { expected, written } => {
-                write!(f, "partial write: expected {} bytes, wrote {}", expected, written)
+                write!(
+                    f,
+                    "partial write: expected {} bytes, wrote {}",
+                    expected, written
+                )
             }
             Self::Poisoned { reason } => {
                 write!(f, "stream poisoned: {}", reason)
             }
             Self::BufferOverflow { limit, attempted } => {
-                write!(f, "buffer overflow: limit {}, attempted {}", limit, attempted)
+                write!(
+                    f,
+                    "buffer overflow: limit {}, attempted {}",
+                    limit, attempted
+                )
             }
             Self::InvalidFrame { details } => {
                 write!(f, "invalid frame: {}", details)
@@ -90,9 +85,7 @@ impl From<StreamError> for std::io::Error {
             StreamError::UnexpectedEof => {
                 std::io::Error::new(std::io::ErrorKind::UnexpectedEof, err)
             }
-            StreamError::Poisoned { .. } => {
-                std::io::Error::other(err)
-            }
+            StreamError::Poisoned { .. } => std::io::Error::other(err),
             StreamError::BufferOverflow { .. } => {
                 std::io::Error::new(std::io::ErrorKind::OutOfMemory, err)
             }
@@ -135,7 +128,10 @@ impl Recoverable for StreamError {
     }
 
     fn can_continue(&self) -> bool {
-        !matches!(self, Self::Poisoned { .. } | Self::UnexpectedEof | Self::BufferOverflow { .. })
+        !matches!(
+            self,
+            Self::Poisoned { .. } | Self::UnexpectedEof | Self::BufferOverflow { .. }
+        )
     }
 }
 
@@ -165,7 +161,6 @@ impl Recoverable for std::io::Error {
 #[derive(Error, Debug)]
 pub enum ProxyError {
     // ============= Crypto Errors =============
-    
     #[error("Crypto error: {0}")]
     Crypto(String),
 
@@ -173,12 +168,10 @@ pub enum ProxyError {
     InvalidKeyLength { expected: usize, got: usize },
 
     // ============= Stream Errors =============
-    
     #[error("Stream error: {0}")]
     Stream(#[from] StreamError),
 
     // ============= Protocol Errors =============
-    
     #[error("Invalid handshake: {0}")]
     InvalidHandshake(String),
 
@@ -210,7 +203,6 @@ pub enum ProxyError {
     TgHandshakeTimeout,
 
     // ============= Network Errors =============
-    
     #[error("Connection timeout to {addr}")]
     ConnectionTimeout { addr: String },
 
@@ -221,15 +213,16 @@ pub enum ProxyError {
     Io(#[from] std::io::Error),
 
     // ============= Proxy Protocol Errors =============
-    
     #[error("Invalid proxy protocol header")]
     InvalidProxyProtocol,
 
+    #[error("Unknown TLS SNI")]
+    UnknownTlsSni,
+
     #[error("Proxy error: {0}")]
     Proxy(String),
 
     // ============= Config Errors =============
-    
     #[error("Config error: {0}")]
     Config(String),
 
@@ -237,7 +230,6 @@ pub enum ProxyError {
     InvalidSecret { user: String, reason: String },
 
     // ============= User Errors =============
-    
     #[error("User {user} expired")]
     UserExpired { user: String },
 
@@ -254,7 +246,6 @@ pub enum ProxyError {
     RateLimited,
 
     // ============= General Errors =============
-    
     #[error("Internal error: {0}")]
     Internal(String),
 }
@@ -311,7 +302,9 @@ impl<T, R, W> HandshakeResult<T, R, W> {
     pub fn map<U, F: FnOnce(T) -> U>(self, f: F) -> HandshakeResult<U, R, W> {
         match self {
             HandshakeResult::Success(v) => HandshakeResult::Success(f(v)),
-            HandshakeResult::BadClient { reader, writer } => HandshakeResult::BadClient { reader, writer },
+            HandshakeResult::BadClient { reader, writer } => {
+                HandshakeResult::BadClient { reader, writer }
+            }
             HandshakeResult::Error(e) => HandshakeResult::Error(e),
         }
     }
@@ -341,18 +334,35 @@ mod tests {
 
     #[test]
     fn test_stream_error_display() {
-        let err = StreamError::PartialRead { expected: 100, got: 50 };
+        let err = StreamError::PartialRead {
+            expected: 100,
+            got: 50,
+        };
         assert!(err.to_string().contains("100"));
         assert!(err.to_string().contains("50"));
 
-        let err = StreamError::Poisoned { reason: "test".into() };
+        let err = StreamError::Poisoned {
+            reason: "test".into(),
+        };
         assert!(err.to_string().contains("test"));
     }
 
     #[test]
     fn test_stream_error_recoverable() {
-        assert!(StreamError::PartialRead { expected: 10, got: 5 }.is_recoverable());
-        assert!(StreamError::PartialWrite { expected: 10, written: 5 }.is_recoverable());
+        assert!(
+            StreamError::PartialRead {
+                expected: 10,
+                got: 5
+            }
+            .is_recoverable()
+        );
+        assert!(
+            StreamError::PartialWrite {
+                expected: 10,
+                written: 5
+            }
+            .is_recoverable()
+        );
         assert!(!StreamError::Poisoned { reason: "x".into() }.is_recoverable());
         assert!(!StreamError::UnexpectedEof.is_recoverable());
     }
@@ -361,7 +371,13 @@ mod tests {
     fn test_stream_error_can_continue() {
         assert!(!StreamError::Poisoned { reason: "x".into() }.can_continue());
         assert!(!StreamError::UnexpectedEof.can_continue());
-        assert!(StreamError::PartialRead { expected: 10, got: 5 }.can_continue());
+        assert!(
+            StreamError::PartialRead {
+                expected: 10,
+                got: 5
+            }
+            .can_continue()
+        );
     }
 
     #[test]
@@ -377,7 +393,10 @@ mod tests {
         assert!(success.is_success());
         assert!(!success.is_bad_client());
 
-        let bad: HandshakeResult<i32, (), ()> = HandshakeResult::BadClient { reader: (), writer: () };
+        let bad: HandshakeResult<i32, (), ()> = HandshakeResult::BadClient {
+            reader: (),
+            writer: (),
+        };
         assert!(!bad.is_success());
         assert!(bad.is_bad_client());
     }
@@ -404,7 +423,9 @@ mod tests {
 
     #[test]
     fn test_error_display() {
-        let err = ProxyError::ConnectionTimeout { addr: "1.2.3.4:443".into() };
+        let err = ProxyError::ConnectionTimeout {
+            addr: "1.2.3.4:443".into(),
+        };
         assert!(err.to_string().contains("1.2.3.4:443"));
 
         let err = ProxyError::InvalidProxyProtocol;

src/ip_tracker.rs

@@ -5,10 +5,11 @@
 use std::collections::HashMap;
 use std::net::IpAddr;
 use std::sync::Arc;
+use std::sync::Mutex;
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::time::{Duration, Instant};
 
-use tokio::sync::RwLock;
+use tokio::sync::{Mutex as AsyncMutex, RwLock};
 
 use crate::config::UserMaxUniqueIpsMode;
 
@@ -21,6 +22,8 @@ pub struct UserIpTracker {
     limit_mode: Arc<RwLock<UserMaxUniqueIpsMode>>,
     limit_window: Arc<RwLock<Duration>>,
     last_compact_epoch_secs: Arc<AtomicU64>,
+    cleanup_queue: Arc<Mutex<Vec<(String, IpAddr)>>>,
+    cleanup_drain_lock: Arc<AsyncMutex<()>>,
 }
 
 impl UserIpTracker {
@@ -33,6 +36,79 @@ impl UserIpTracker {
             limit_mode: Arc::new(RwLock::new(UserMaxUniqueIpsMode::ActiveWindow)),
             limit_window: Arc::new(RwLock::new(Duration::from_secs(30))),
             last_compact_epoch_secs: Arc::new(AtomicU64::new(0)),
+            cleanup_queue: Arc::new(Mutex::new(Vec::new())),
+            cleanup_drain_lock: Arc::new(AsyncMutex::new(())),
+        }
+    }
+
+    pub fn enqueue_cleanup(&self, user: String, ip: IpAddr) {
+        match self.cleanup_queue.lock() {
+            Ok(mut queue) => queue.push((user, ip)),
+            Err(poisoned) => {
+                let mut queue = poisoned.into_inner();
+                queue.push((user.clone(), ip));
+                self.cleanup_queue.clear_poison();
+                tracing::warn!(
+                    "UserIpTracker cleanup_queue lock poisoned; recovered and enqueued IP cleanup for {} ({})",
+                    user,
+                    ip
+                );
+            }
+        }
+    }
+
+    #[cfg(test)]
+    pub(crate) fn cleanup_queue_len_for_tests(&self) -> usize {
+        self.cleanup_queue
+            .lock()
+            .unwrap_or_else(|poisoned| poisoned.into_inner())
+            .len()
+    }
+
+    #[cfg(test)]
+    pub(crate) fn cleanup_queue_mutex_for_tests(&self) -> Arc<Mutex<Vec<(String, IpAddr)>>> {
+        Arc::clone(&self.cleanup_queue)
+    }
+
+    pub(crate) async fn drain_cleanup_queue(&self) {
+        // Serialize queue draining and active-IP mutation so check-and-add cannot
+        // observe stale active entries that are already queued for removal.
+        let _drain_guard = self.cleanup_drain_lock.lock().await;
+        let to_remove = {
+            match self.cleanup_queue.lock() {
+                Ok(mut queue) => {
+                    if queue.is_empty() {
+                        return;
+                    }
+                    std::mem::take(&mut *queue)
+                }
+                Err(poisoned) => {
+                    let mut queue = poisoned.into_inner();
+                    if queue.is_empty() {
+                        self.cleanup_queue.clear_poison();
+                        return;
+                    }
+                    let drained = std::mem::take(&mut *queue);
+                    self.cleanup_queue.clear_poison();
+                    drained
+                }
+            }
+        };
+
+        let mut active_ips = self.active_ips.write().await;
+        for (user, ip) in to_remove {
+            if let Some(user_ips) = active_ips.get_mut(&user) {
+                if let Some(count) = user_ips.get_mut(&ip) {
+                    if *count > 1 {
+                        *count -= 1;
+                    } else {
+                        user_ips.remove(&ip);
+                    }
+                }
+                if user_ips.is_empty() {
+                    active_ips.remove(&user);
+                }
+            }
         }
     }
 
@@ -65,7 +141,8 @@ impl UserIpTracker {
 
         let mut active_ips = self.active_ips.write().await;
         let mut recent_ips = self.recent_ips.write().await;
-        let mut users = Vec::<String>::with_capacity(active_ips.len().saturating_add(recent_ips.len()));
+        let mut users =
+            Vec::<String>::with_capacity(active_ips.len().saturating_add(recent_ips.len()));
         users.extend(active_ips.keys().cloned());
         for user in recent_ips.keys() {
             if !active_ips.contains_key(user) {
@@ -74,8 +151,14 @@ impl UserIpTracker {
         }
 
         for user in users {
-            let active_empty = active_ips.get(&user).map(|ips| ips.is_empty()).unwrap_or(true);
-            let recent_empty = recent_ips.get(&user).map(|ips| ips.is_empty()).unwrap_or(true);
+            let active_empty = active_ips
+                .get(&user)
+                .map(|ips| ips.is_empty())
+                .unwrap_or(true);
+            let recent_empty = recent_ips
+                .get(&user)
+                .map(|ips| ips.is_empty())
+                .unwrap_or(true);
             if active_empty && recent_empty {
                 active_ips.remove(&user);
                 recent_ips.remove(&user);
@@ -118,6 +201,7 @@ impl UserIpTracker {
     }
 
     pub async fn check_and_add(&self, username: &str, ip: IpAddr) -> Result<(), String> {
+        self.drain_cleanup_queue().await;
         self.maybe_compact_empty_users().await;
         let default_max_ips = *self.default_max_ips.read().await;
         let limit = {
@@ -194,6 +278,7 @@ impl UserIpTracker {
     }
 
     pub async fn get_recent_counts_for_users(&self, users: &[String]) -> HashMap<String, usize> {
+        self.drain_cleanup_queue().await;
         let window = *self.limit_window.read().await;
         let now = Instant::now();
         let recent_ips = self.recent_ips.read().await;
@@ -214,6 +299,7 @@ impl UserIpTracker {
     }
 
     pub async fn get_active_ips_for_users(&self, users: &[String]) -> HashMap<String, Vec<IpAddr>> {
+        self.drain_cleanup_queue().await;
         let active_ips = self.active_ips.read().await;
         let mut out = HashMap::with_capacity(users.len());
         for user in users {
@@ -228,6 +314,7 @@ impl UserIpTracker {
     }
 
     pub async fn get_recent_ips_for_users(&self, users: &[String]) -> HashMap<String, Vec<IpAddr>> {
+        self.drain_cleanup_queue().await;
         let window = *self.limit_window.read().await;
         let now = Instant::now();
         let recent_ips = self.recent_ips.read().await;
@@ -250,11 +337,13 @@ impl UserIpTracker {
     }
 
     pub async fn get_active_ip_count(&self, username: &str) -> usize {
+        self.drain_cleanup_queue().await;
         let active_ips = self.active_ips.read().await;
         active_ips.get(username).map(|ips| ips.len()).unwrap_or(0)
     }
 
     pub async fn get_active_ips(&self, username: &str) -> Vec<IpAddr> {
+        self.drain_cleanup_queue().await;
         let active_ips = self.active_ips.read().await;
         active_ips
             .get(username)
@@ -263,6 +352,7 @@ impl UserIpTracker {
     }
 
     pub async fn get_stats(&self) -> Vec<(String, usize, usize)> {
+        self.drain_cleanup_queue().await;
         let active_ips = self.active_ips.read().await;
         let max_ips = self.max_ips.read().await;
         let default_max_ips = *self.default_max_ips.read().await;
@@ -301,6 +391,7 @@ impl UserIpTracker {
     }
 
     pub async fn is_ip_active(&self, username: &str, ip: IpAddr) -> bool {
+        self.drain_cleanup_queue().await;
         let active_ips = self.active_ips.read().await;
         active_ips
             .get(username)

src/maestro/admission.rs

@@ -21,10 +21,29 @@ pub(crate) async fn configure_admission_gate(
     if config.general.use_middle_proxy {
         if let Some(pool) = me_pool.as_ref() {
             let initial_ready = pool.admission_ready_conditional_cast().await;
-            admission_tx.send_replace(initial_ready);
-            let _ = route_runtime.set_mode(RelayRouteMode::Middle);
+            let mut fallback_enabled = config.general.me2dc_fallback;
+            let mut fast_fallback_enabled = fallback_enabled && config.general.me2dc_fast;
+            let (initial_gate_open, initial_route_mode, initial_fallback_reason) = if initial_ready
+            {
+                (true, RelayRouteMode::Middle, None)
+            } else if fast_fallback_enabled {
+                (
+                    true,
+                    RelayRouteMode::Direct,
+                    Some("fast_not_ready_fallback"),
+                )
+            } else {
+                (false, RelayRouteMode::Middle, None)
+            };
+            admission_tx.send_replace(initial_gate_open);
+            let _ = route_runtime.set_mode(initial_route_mode);
             if initial_ready {
                 info!("Conditional-admission gate: open / ME pool READY");
+            } else if let Some(reason) = initial_fallback_reason {
+                warn!(
+                    fallback_reason = reason,
+                    "Conditional-admission gate opened in ME fast fallback mode"
+                );
             } else {
                 warn!("Conditional-admission gate: closed / ME pool is NOT ready)");
             }
@@ -34,10 +53,9 @@ pub(crate) async fn configure_admission_gate(
             let route_runtime_gate = route_runtime.clone();
             let mut config_rx_gate = config_rx.clone();
             let mut admission_poll_ms = config.general.me_admission_poll_ms.max(1);
-            let mut fallback_enabled = config.general.me2dc_fallback;
             tokio::spawn(async move {
-                let mut gate_open = initial_ready;
-                let mut route_mode = RelayRouteMode::Middle;
+                let mut gate_open = initial_gate_open;
+                let mut route_mode = initial_route_mode;
                 let mut ready_observed = initial_ready;
                 let mut not_ready_since = if initial_ready {
                     None
@@ -53,16 +71,23 @@ pub(crate) async fn configure_admission_gate(
                             let cfg = config_rx_gate.borrow_and_update().clone();
                             admission_poll_ms = cfg.general.me_admission_poll_ms.max(1);
                             fallback_enabled = cfg.general.me2dc_fallback;
+                            fast_fallback_enabled = cfg.general.me2dc_fallback && cfg.general.me2dc_fast;
                             continue;
                         }
                         _ = tokio::time::sleep(Duration::from_millis(admission_poll_ms)) => {}
                     }
                     let ready = pool_for_gate.admission_ready_conditional_cast().await;
                     let now = Instant::now();
-                    let (next_gate_open, next_route_mode, next_fallback_active) = if ready {
+                    let (next_gate_open, next_route_mode, next_fallback_reason) = if ready {
                         ready_observed = true;
                         not_ready_since = None;
-                        (true, RelayRouteMode::Middle, false)
+                        (true, RelayRouteMode::Middle, None)
+                    } else if fast_fallback_enabled {
+                        (
+                            true,
+                            RelayRouteMode::Direct,
+                            Some("fast_not_ready_fallback"),
+                        )
                     } else {
                         let not_ready_started_at = *not_ready_since.get_or_insert(now);
                         let not_ready_for = now.saturating_duration_since(not_ready_started_at);
@@ -72,11 +97,12 @@ pub(crate) async fn configure_admission_gate(
                             STARTUP_FALLBACK_AFTER
                         };
                         if fallback_enabled && not_ready_for > fallback_after {
-                            (true, RelayRouteMode::Direct, true)
+                            (true, RelayRouteMode::Direct, Some("strict_grace_fallback"))
                         } else {
-                            (false, RelayRouteMode::Middle, false)
+                            (false, RelayRouteMode::Middle, None)
                         }
                     };
+                    let next_fallback_active = next_fallback_reason.is_some();
 
                     if next_route_mode != route_mode {
                         route_mode = next_route_mode;
@@ -88,6 +114,8 @@ pub(crate) async fn configure_admission_gate(
                                     "Middle-End routing restored for new sessions"
                                 );
                             } else {
+                                let fallback_reason = next_fallback_reason.unwrap_or("unknown");
+                                if fallback_reason == "strict_grace_fallback" {
                                     let fallback_after = if ready_observed {
                                         RUNTIME_FALLBACK_AFTER
                                     } else {
@@ -97,8 +125,17 @@ pub(crate) async fn configure_admission_gate(
                                         target_mode = route_mode.as_str(),
                                         cutover_generation = snapshot.generation,
                                         grace_secs = fallback_after.as_secs(),
+                                        fallback_reason,
                                         "ME pool stayed not-ready beyond grace; routing new sessions via Direct-DC"
                                     );
+                                } else {
+                                    warn!(
+                                        target_mode = route_mode.as_str(),
+                                        cutover_generation = snapshot.generation,
+                                        fallback_reason,
+                                        "ME pool not-ready; routing new sessions via Direct-DC (fast mode)"
+                                    );
+                                }
                             }
                         }
                     }
@@ -108,7 +145,10 @@ pub(crate) async fn configure_admission_gate(
                         admission_tx_gate.send_replace(gate_open);
                         if gate_open {
                             if next_fallback_active {
-                                warn!("Conditional-admission gate opened in ME fallback mode");
+                                warn!(
+                                    fallback_reason = next_fallback_reason.unwrap_or("unknown"),
+                                    "Conditional-admission gate opened in ME fallback mode"
+                                );
                             } else {
                                 info!("Conditional-admission gate opened / ME pool READY");
                             }

src/maestro/connectivity.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::too_many_arguments)]
+
 use std::sync::Arc;
 use std::time::Instant;
 
@@ -11,10 +13,10 @@ use crate::startup::{
     COMPONENT_DC_CONNECTIVITY_PING, COMPONENT_ME_CONNECTIVITY_PING, COMPONENT_RUNTIME_READY,
     StartupTracker,
 };
+use crate::transport::UpstreamManager;
 use crate::transport::middle_proxy::{
     MePingFamily, MePingSample, MePool, format_me_route, format_sample_line, run_me_ping,
 };
-use crate::transport::UpstreamManager;
 
 pub(crate) async fn run_startup_connectivity(
     config: &Arc<ProxyConfig>,
@@ -47,11 +49,15 @@ pub(crate) async fn run_startup_connectivity(
 
         let v4_ok = me_results.iter().any(|r| {
             matches!(r.family, MePingFamily::V4)
-                && r.samples.iter().any(|s| s.error.is_none() && s.handshake_ms.is_some())
+                && r.samples
+                    .iter()
+                    .any(|s| s.error.is_none() && s.handshake_ms.is_some())
         });
         let v6_ok = me_results.iter().any(|r| {
             matches!(r.family, MePingFamily::V6)
-                && r.samples.iter().any(|s| s.error.is_none() && s.handshake_ms.is_some())
+                && r.samples
+                    .iter()
+                    .any(|s| s.error.is_none() && s.handshake_ms.is_some())
         });
 
         info!("================= Telegram ME Connectivity =================");
@@ -131,8 +137,14 @@ pub(crate) async fn run_startup_connectivity(
         .await;
 
     for upstream_result in &ping_results {
-        let v6_works = upstream_result.v6_results.iter().any(|r| r.rtt_ms.is_some());
-        let v4_works = upstream_result.v4_results.iter().any(|r| r.rtt_ms.is_some());
+        let v6_works = upstream_result
+            .v6_results
+            .iter()
+            .any(|r| r.rtt_ms.is_some());
+        let v4_works = upstream_result
+            .v4_results
+            .iter()
+            .any(|r| r.rtt_ms.is_some());
 
         if upstream_result.both_available {
             if prefer_ipv6 {

src/maestro/helpers.rs

@@ -1,15 +1,32 @@
-use std::time::Duration;
+#![allow(clippy::items_after_test_module)]
+
 use std::path::PathBuf;
+use std::time::Duration;
 
 use tokio::sync::watch;
 use tracing::{debug, error, info, warn};
 
 use crate::cli;
 use crate::config::ProxyConfig;
+use crate::transport::UpstreamManager;
 use crate::transport::middle_proxy::{
-    ProxyConfigData, fetch_proxy_config_with_raw, load_proxy_config_cache, save_proxy_config_cache,
+    ProxyConfigData, fetch_proxy_config_with_raw_via_upstream, load_proxy_config_cache,
+    save_proxy_config_cache,
 };
 
+pub(crate) fn resolve_runtime_config_path(
+    config_path_cli: &str,
+    startup_cwd: &std::path::Path,
+) -> PathBuf {
+    let raw = PathBuf::from(config_path_cli);
+    let absolute = if raw.is_absolute() {
+        raw
+    } else {
+        startup_cwd.join(raw)
+    };
+    absolute.canonicalize().unwrap_or(absolute)
+}
+
 pub(crate) fn parse_cli() -> (String, Option<PathBuf>, bool, Option<String>) {
     let mut config_path = "config.toml".to_string();
     let mut data_path: Option<PathBuf> = None;
@@ -40,7 +57,9 @@ pub(crate) fn parse_cli() -> (String, Option<PathBuf>, bool, Option<String>) {
                 }
             }
             s if s.starts_with("--data-path=") => {
-                data_path = Some(PathBuf::from(s.trim_start_matches("--data-path=").to_string()));
+                data_path = Some(PathBuf::from(
+                    s.trim_start_matches("--data-path=").to_string(),
+                ));
             }
             "--silent" | "-s" => {
                 silent = true;
@@ -58,7 +77,9 @@ pub(crate) fn parse_cli() -> (String, Option<PathBuf>, bool, Option<String>) {
                 eprintln!("Usage: telemt [config.toml] [OPTIONS]");
                 eprintln!();
                 eprintln!("Options:");
-                eprintln!("  --data-path <DIR>       Set data directory (absolute path; overrides config value)");
+                eprintln!(
+                    "  --data-path <DIR>       Set data directory (absolute path; overrides config value)"
+                );
                 eprintln!("  --silent, -s            Suppress info logs");
                 eprintln!("  --log-level <LEVEL>     debug|verbose|normal|silent");
                 eprintln!("  --help, -h              Show this help");
@@ -96,9 +117,52 @@ pub(crate) fn parse_cli() -> (String, Option<PathBuf>, bool, Option<String>) {
     (config_path, data_path, silent, log_level)
 }
 
+#[cfg(test)]
+mod tests {
+    use super::resolve_runtime_config_path;
+
+    #[test]
+    fn resolve_runtime_config_path_anchors_relative_to_startup_cwd() {
+        let nonce = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap()
+            .as_nanos();
+        let startup_cwd = std::env::temp_dir().join(format!("telemt_cfg_path_{nonce}"));
+        std::fs::create_dir_all(&startup_cwd).unwrap();
+        let target = startup_cwd.join("config.toml");
+        std::fs::write(&target, " ").unwrap();
+
+        let resolved = resolve_runtime_config_path("config.toml", &startup_cwd);
+        assert_eq!(resolved, target.canonicalize().unwrap());
+
+        let _ = std::fs::remove_file(&target);
+        let _ = std::fs::remove_dir(&startup_cwd);
+    }
+
+    #[test]
+    fn resolve_runtime_config_path_keeps_absolute_for_missing_file() {
+        let nonce = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap()
+            .as_nanos();
+        let startup_cwd = std::env::temp_dir().join(format!("telemt_cfg_path_missing_{nonce}"));
+        std::fs::create_dir_all(&startup_cwd).unwrap();
+
+        let resolved = resolve_runtime_config_path("missing.toml", &startup_cwd);
+        assert_eq!(resolved, startup_cwd.join("missing.toml"));
+
+        let _ = std::fs::remove_dir(&startup_cwd);
+    }
+}
+
 pub(crate) fn print_proxy_links(host: &str, port: u16, config: &ProxyConfig) {
     info!(target: "telemt::links", "--- Proxy Links ({}) ---", host);
-    for user_name in config.general.links.show.resolve_users(&config.access.users) {
+    for user_name in config
+        .general
+        .links
+        .show
+        .resolve_users(&config.access.users)
+    {
         if let Some(secret) = config.access.users.get(user_name) {
             info!(target: "telemt::links", "User: {}", user_name);
             if config.general.modes.classic {
@@ -226,9 +290,10 @@ pub(crate) async fn load_startup_proxy_config_snapshot(
     cache_path: Option<&str>,
     me2dc_fallback: bool,
     label: &'static str,
+    upstream: Option<std::sync::Arc<UpstreamManager>>,
 ) -> Option<ProxyConfigData> {
     loop {
-        match fetch_proxy_config_with_raw(url).await {
+        match fetch_proxy_config_with_raw_via_upstream(url, upstream.clone()).await {
             Ok((cfg, raw)) => {
                 if !cfg.map.is_empty() {
                     if let Some(path) = cache_path
@@ -239,7 +304,10 @@ pub(crate) async fn load_startup_proxy_config_snapshot(
                     return Some(cfg);
                 }
 
-                warn!(snapshot = label, url, "Startup proxy-config is empty; trying disk cache");
+                warn!(
+                    snapshot = label,
+                    url, "Startup proxy-config is empty; trying disk cache"
+                );
                 if let Some(path) = cache_path {
                     match load_proxy_config_cache(path).await {
                         Ok(cached) if !cached.map.is_empty() => {
@@ -254,8 +322,7 @@ pub(crate) async fn load_startup_proxy_config_snapshot(
                         Ok(_) => {
                             warn!(
                                 snapshot = label,
-                                path,
-                                "Startup proxy-config cache is empty; ignoring cache file"
+                                path, "Startup proxy-config cache is empty; ignoring cache file"
                             );
                         }
                         Err(cache_err) => {
@@ -299,8 +366,7 @@ pub(crate) async fn load_startup_proxy_config_snapshot(
                         Ok(_) => {
                             warn!(
                                 snapshot = label,
-                                path,
-                                "Startup proxy-config cache is empty; ignoring cache file"
+                                path, "Startup proxy-config cache is empty; ignoring cache file"
                             );
                         }
                         Err(cache_err) => {

src/maestro/listeners.rs

@@ -12,17 +12,15 @@ use tracing::{debug, error, info, warn};
 use crate::config::ProxyConfig;
 use crate::crypto::SecureRandom;
 use crate::ip_tracker::UserIpTracker;
-use crate::proxy::route_mode::{ROUTE_SWITCH_ERROR_MSG, RouteRuntimeController};
 use crate::proxy::ClientHandler;
+use crate::proxy::route_mode::{ROUTE_SWITCH_ERROR_MSG, RouteRuntimeController};
 use crate::startup::{COMPONENT_LISTENERS_BIND, StartupTracker};
 use crate::stats::beobachten::BeobachtenStore;
 use crate::stats::{ReplayChecker, Stats};
 use crate::stream::BufferPool;
 use crate::tls_front::TlsFrontCache;
 use crate::transport::middle_proxy::MePool;
-use crate::transport::{
-    ListenOptions, UpstreamManager, create_listener, find_listener_processes,
-};
+use crate::transport::{ListenOptions, UpstreamManager, create_listener, find_listener_processes};
 
 use super::helpers::{is_expected_handshake_eof, print_proxy_links};
 
@@ -81,8 +79,9 @@ pub(crate) async fn bind_listeners(
             Ok(socket) => {
                 let listener = TcpListener::from_std(socket.into())?;
                 info!("Listening on {}", addr);
-                let listener_proxy_protocol =
-                    listener_conf.proxy_protocol.unwrap_or(config.server.proxy_protocol);
+                let listener_proxy_protocol = listener_conf
+                    .proxy_protocol
+                    .unwrap_or(config.server.proxy_protocol);
 
                 let public_host = if let Some(ref announce) = listener_conf.announce {
                     announce.clone()
@@ -100,8 +99,14 @@ pub(crate) async fn bind_listeners(
                     listener_conf.ip.to_string()
                 };
 
-                if config.general.links.public_host.is_none() && !config.general.links.show.is_empty() {
-                    let link_port = config.general.links.public_port.unwrap_or(config.server.port);
+                if config.general.links.public_host.is_none()
+                    && !config.general.links.show.is_empty()
+                {
+                    let link_port = config
+                        .general
+                        .links
+                        .public_port
+                        .unwrap_or(config.server.port);
                     print_proxy_links(&public_host, link_port, config);
                 }
 
@@ -145,12 +150,14 @@ pub(crate) async fn bind_listeners(
         let (host, port) = if let Some(ref h) = config.general.links.public_host {
             (
                 h.clone(),
-                config.general.links.public_port.unwrap_or(config.server.port),
+                config
+                    .general
+                    .links
+                    .public_port
+                    .unwrap_or(config.server.port),
             )
         } else {
-            let ip = detected_ip_v4
-                .or(detected_ip_v6)
-                .map(|ip| ip.to_string());
+            let ip = detected_ip_v4.or(detected_ip_v6).map(|ip| ip.to_string());
             if ip.is_none() {
                 warn!(
                     "show_link is configured but public IP could not be detected. Set public_host in config."
@@ -158,7 +165,11 @@ pub(crate) async fn bind_listeners(
             }
             (
                 ip.unwrap_or_else(|| "UNKNOWN".to_string()),
-                config.general.links.public_port.unwrap_or(config.server.port),
+                config
+                    .general
+                    .links
+                    .public_port
+                    .unwrap_or(config.server.port),
             )
         };
 
@@ -178,13 +189,19 @@ pub(crate) async fn bind_listeners(
                     use std::os::unix::fs::PermissionsExt;
                     let perms = std::fs::Permissions::from_mode(mode);
                     if let Err(e) = std::fs::set_permissions(unix_path, perms) {
-                        error!("Failed to set unix socket permissions to {}: {}", perm_str, e);
+                        error!(
+                            "Failed to set unix socket permissions to {}: {}",
+                            perm_str, e
+                        );
                     } else {
                         info!("Listening on unix:{} (mode {})", unix_path, perm_str);
                     }
                 }
                 Err(e) => {
-                    warn!("Invalid listen_unix_sock_perm '{}': {}. Ignoring.", perm_str, e);
+                    warn!(
+                        "Invalid listen_unix_sock_perm '{}': {}. Ignoring.",
+                        perm_str, e
+                    );
                     info!("Listening on unix:{}", unix_path);
                 }
             }
@@ -218,10 +235,8 @@ pub(crate) async fn bind_listeners(
                             drop(stream);
                             continue;
                         }
-                        let accept_permit_timeout_ms = config_rx_unix
-                            .borrow()
-                            .server
-                            .accept_permit_timeout_ms;
+                        let accept_permit_timeout_ms =
+                            config_rx_unix.borrow().server.accept_permit_timeout_ms;
                         let permit = if accept_permit_timeout_ms == 0 {
                             match max_connections_unix.clone().acquire_owned().await {
                                 Ok(permit) => permit,
@@ -361,10 +376,8 @@ pub(crate) fn spawn_tcp_accept_loops(
                             drop(stream);
                             continue;
                         }
-                        let accept_permit_timeout_ms = config_rx
-                            .borrow()
-                            .server
-                            .accept_permit_timeout_ms;
+                        let accept_permit_timeout_ms =
+                            config_rx.borrow().server.accept_permit_timeout_ms;
                         let permit = if accept_permit_timeout_ms == 0 {
                             match max_connections_tcp.clone().acquire_owned().await {
                                 Ok(permit) => permit,

src/maestro/me_startup.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::too_many_arguments)]
+
 use std::sync::Arc;
 use std::time::Duration;
 
@@ -12,8 +14,8 @@ use crate::startup::{
     COMPONENT_ME_PROXY_CONFIG_V6, COMPONENT_ME_SECRET_FETCH, StartupMeStatus, StartupTracker,
 };
 use crate::stats::Stats;
-use crate::transport::middle_proxy::MePool;
 use crate::transport::UpstreamManager;
+use crate::transport::middle_proxy::MePool;
 
 use super::helpers::load_startup_proxy_config_snapshot;
 
@@ -61,9 +63,10 @@ pub(crate) async fn initialize_me_pool(
     let proxy_secret_path = config.general.proxy_secret_path.as_deref();
     let pool_size = config.general.middle_proxy_pool_size.max(1);
     let proxy_secret = loop {
-        match crate::transport::middle_proxy::fetch_proxy_secret(
+        match crate::transport::middle_proxy::fetch_proxy_secret_with_upstream(
             proxy_secret_path,
             config.general.proxy_secret_len_max,
+            Some(upstream_manager.clone()),
         )
         .await
         {
@@ -127,6 +130,7 @@ pub(crate) async fn initialize_me_pool(
                 config.general.proxy_config_v4_cache_path.as_deref(),
                 me2dc_fallback,
                 "getProxyConfig",
+                Some(upstream_manager.clone()),
             )
             .await;
             if cfg_v4.is_some() {
@@ -158,6 +162,7 @@ pub(crate) async fn initialize_me_pool(
                 config.general.proxy_config_v6_cache_path.as_deref(),
                 me2dc_fallback,
                 "getProxyConfigV6",
+                Some(upstream_manager.clone()),
             )
             .await;
             if cfg_v6.is_some() {
@@ -229,8 +234,12 @@ pub(crate) async fn initialize_me_pool(
                     config.general.me_adaptive_floor_recover_grace_secs,
                     config.general.me_adaptive_floor_writers_per_core_total,
                     config.general.me_adaptive_floor_cpu_cores_override,
-                    config.general.me_adaptive_floor_max_extra_writers_single_per_core,
-                    config.general.me_adaptive_floor_max_extra_writers_multi_per_core,
+                    config
+                        .general
+                        .me_adaptive_floor_max_extra_writers_single_per_core,
+                    config
+                        .general
+                        .me_adaptive_floor_max_extra_writers_multi_per_core,
                     config.general.me_adaptive_floor_max_active_writers_per_core,
                     config.general.me_adaptive_floor_max_warm_writers_per_core,
                     config.general.me_adaptive_floor_max_active_writers_global,
@@ -475,7 +484,9 @@ pub(crate) async fn initialize_me_pool(
                                         })
                                         .await;
                                         match res {
-                                                Ok(()) => warn!("me_health_monitor exited unexpectedly, restarting"),
+                                            Ok(()) => warn!(
+                                                "me_health_monitor exited unexpectedly, restarting"
+                                            ),
                                             Err(e) => {
                                                 error!(error = %e, "me_health_monitor panicked, restarting in 1s");
                                                 tokio::time::sleep(Duration::from_secs(1)).await;
@@ -492,7 +503,9 @@ pub(crate) async fn initialize_me_pool(
                                             })
                                             .await;
                                         match res {
-                                                Ok(()) => warn!("me_drain_timeout_enforcer exited unexpectedly, restarting"),
+                                            Ok(()) => warn!(
+                                                "me_drain_timeout_enforcer exited unexpectedly, restarting"
+                                            ),
                                             Err(e) => {
                                                 error!(error = %e, "me_drain_timeout_enforcer panicked, restarting in 1s");
                                                 tokio::time::sleep(Duration::from_secs(1)).await;
@@ -509,7 +522,9 @@ pub(crate) async fn initialize_me_pool(
                                             })
                                             .await;
                                         match res {
-                                                Ok(()) => warn!("me_zombie_writer_watchdog exited unexpectedly, restarting"),
+                                            Ok(()) => warn!(
+                                                "me_zombie_writer_watchdog exited unexpectedly, restarting"
+                                            ),
                                             Err(e) => {
                                                 error!(error = %e, "me_zombie_writer_watchdog panicked, restarting in 1s");
                                                 tokio::time::sleep(Duration::from_secs(1)).await;

src/maestro/mod.rs

@@ -11,9 +11,9 @@
 // - admission: conditional-cast gate and route mode switching.
 // - listeners: TCP/Unix listener bind and accept-loop orchestration.
 // - shutdown: graceful shutdown sequence and uptime logging.
-mod helpers;
 mod admission;
 mod connectivity;
+mod helpers;
 mod listeners;
 mod me_startup;
 mod runtime_tasks;
@@ -33,19 +33,19 @@ use crate::crypto::SecureRandom;
 use crate::ip_tracker::UserIpTracker;
 use crate::network::probe::{decide_network_capabilities, log_probe_result, run_probe};
 use crate::proxy::route_mode::{RelayRouteMode, RouteRuntimeController};
+use crate::startup::{
+    COMPONENT_API_BOOTSTRAP, COMPONENT_CONFIG_LOAD, COMPONENT_ME_POOL_CONSTRUCT,
+    COMPONENT_ME_POOL_INIT_STAGE1, COMPONENT_ME_PROXY_CONFIG_V4, COMPONENT_ME_PROXY_CONFIG_V6,
+    COMPONENT_ME_SECRET_FETCH, COMPONENT_NETWORK_PROBE, COMPONENT_TRACING_INIT, StartupMeStatus,
+    StartupTracker,
+};
 use crate::stats::beobachten::BeobachtenStore;
 use crate::stats::telemetry::TelemetryPolicy;
 use crate::stats::{ReplayChecker, Stats};
-use crate::startup::{
-    COMPONENT_API_BOOTSTRAP, COMPONENT_CONFIG_LOAD,
-    COMPONENT_ME_POOL_CONSTRUCT, COMPONENT_ME_POOL_INIT_STAGE1,
-    COMPONENT_ME_PROXY_CONFIG_V4, COMPONENT_ME_PROXY_CONFIG_V6, COMPONENT_ME_SECRET_FETCH,
-    COMPONENT_NETWORK_PROBE, COMPONENT_TRACING_INIT, StartupMeStatus, StartupTracker,
-};
 use crate::stream::BufferPool;
-use crate::transport::middle_proxy::MePool;
 use crate::transport::UpstreamManager;
-use helpers::parse_cli;
+use crate::transport::middle_proxy::MePool;
+use helpers::{parse_cli, resolve_runtime_config_path};
 
 /// Runs the full telemt runtime startup pipeline and blocks until shutdown.
 pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
@@ -56,20 +56,34 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
         .as_secs();
     let startup_tracker = Arc::new(StartupTracker::new(process_started_at_epoch_secs));
     startup_tracker
-        .start_component(COMPONENT_CONFIG_LOAD, Some("load and validate config".to_string()))
+        .start_component(
+            COMPONENT_CONFIG_LOAD,
+            Some("load and validate config".to_string()),
+        )
         .await;
-    let (config_path, data_path, cli_silent, cli_log_level) = parse_cli();
+    let (config_path_cli, data_path, cli_silent, cli_log_level) = parse_cli();
+    let startup_cwd = match std::env::current_dir() {
+        Ok(cwd) => cwd,
+        Err(e) => {
+            eprintln!("[telemt] Can't read current_dir: {}", e);
+            std::process::exit(1);
+        }
+    };
+    let config_path = resolve_runtime_config_path(&config_path_cli, &startup_cwd);
 
     let mut config = match ProxyConfig::load(&config_path) {
         Ok(c) => c,
         Err(e) => {
-            if std::path::Path::new(&config_path).exists() {
+            if config_path.exists() {
                 eprintln!("[telemt] Error: {}", e);
                 std::process::exit(1);
             } else {
                 let default = ProxyConfig::default();
                 std::fs::write(&config_path, toml::to_string_pretty(&default).unwrap()).unwrap();
-                eprintln!("[telemt] Created default config at {}", config_path);
+                eprintln!(
+                    "[telemt] Created default config at {}",
+                    config_path.display()
+                );
                 default
             }
         }
@@ -86,24 +100,36 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
 
     if let Some(ref data_path) = config.general.data_path {
         if !data_path.is_absolute() {
-            eprintln!("[telemt] data_path must be absolute: {}", data_path.display());
+            eprintln!(
+                "[telemt] data_path must be absolute: {}",
+                data_path.display()
+            );
             std::process::exit(1);
         }
 
         if data_path.exists() {
             if !data_path.is_dir() {
-                eprintln!("[telemt] data_path exists but is not a directory: {}", data_path.display());
+                eprintln!(
+                    "[telemt] data_path exists but is not a directory: {}",
+                    data_path.display()
+                );
                 std::process::exit(1);
             }
-        } else {
-            if let Err(e) = std::fs::create_dir_all(data_path) {
-                eprintln!("[telemt] Can't create data_path {}: {}", data_path.display(), e);
+        } else if let Err(e) = std::fs::create_dir_all(data_path) {
+            eprintln!(
+                "[telemt] Can't create data_path {}: {}",
+                data_path.display(),
+                e
+            );
             std::process::exit(1);
         }
-        }
 
         if let Err(e) = std::env::set_current_dir(data_path) {
-            eprintln!("[telemt] Can't use data_path {}: {}", data_path.display(), e);
+            eprintln!(
+                "[telemt] Can't use data_path {}: {}",
+                data_path.display(),
+                e
+            );
             std::process::exit(1);
         }
     }
@@ -127,7 +153,10 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
 
     let (filter_layer, filter_handle) = reload::Layer::new(EnvFilter::new("info"));
     startup_tracker
-        .start_component(COMPONENT_TRACING_INIT, Some("initialize tracing subscriber".to_string()))
+        .start_component(
+            COMPONENT_TRACING_INIT,
+            Some("initialize tracing subscriber".to_string()),
+        )
         .await;
 
     // Configure color output based on config
@@ -142,7 +171,10 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
         .with(fmt_layer)
         .init();
     startup_tracker
-        .complete_component(COMPONENT_TRACING_INIT, Some("tracing initialized".to_string()))
+        .complete_component(
+            COMPONENT_TRACING_INIT,
+            Some("tracing initialized".to_string()),
+        )
         .await;
 
     info!("Telemt MTProxy v{}", env!("CARGO_PKG_VERSION"));
@@ -191,6 +223,7 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
         config.general.upstream_connect_retry_attempts,
         config.general.upstream_connect_retry_backoff_ms,
         config.general.upstream_connect_budget_ms,
+        config.timeouts.tg_connect,
         config.general.upstream_unhealthy_fail_threshold,
         config.general.upstream_connect_failfast_hard_errors,
         stats.clone(),
@@ -208,7 +241,8 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
             config.access.user_max_unique_ips_window_secs,
         )
         .await;
-    if config.access.user_max_unique_ips_global_each > 0 || !config.access.user_max_unique_ips.is_empty()
+    if config.access.user_max_unique_ips_global_each > 0
+        || !config.access.user_max_unique_ips.is_empty()
     {
         info!(
             global_each_limit = config.access.user_max_unique_ips_global_each,
@@ -235,7 +269,10 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
     let route_runtime = Arc::new(RouteRuntimeController::new(initial_route_mode));
     let api_me_pool = Arc::new(RwLock::new(None::<Arc<MePool>>));
     startup_tracker
-        .start_component(COMPONENT_API_BOOTSTRAP, Some("spawn API listener task".to_string()))
+        .start_component(
+            COMPONENT_API_BOOTSTRAP,
+            Some("spawn API listener task".to_string()),
+        )
         .await;
 
     if config.server.api.enabled {
@@ -258,7 +295,7 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
             let route_runtime_api = route_runtime.clone();
             let config_rx_api = api_config_rx.clone();
             let admission_rx_api = admission_rx.clone();
-            let config_path_api = std::path::PathBuf::from(&config_path);
+            let config_path_api = config_path.clone();
             let startup_tracker_api = startup_tracker.clone();
             let detected_ips_rx_api = detected_ips_rx.clone();
             tokio::spawn(async move {
@@ -318,7 +355,10 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
     .await;
 
     startup_tracker
-        .start_component(COMPONENT_NETWORK_PROBE, Some("probe network capabilities".to_string()))
+        .start_component(
+            COMPONENT_NETWORK_PROBE,
+            Some("probe network capabilities".to_string()),
+        )
         .await;
     let probe = run_probe(
         &config.network,
@@ -331,11 +371,8 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
         probe.detected_ipv4.map(IpAddr::V4),
         probe.detected_ipv6.map(IpAddr::V6),
     ));
-    let decision = decide_network_capabilities(
-        &config.network,
-        &probe,
-        config.general.middle_proxy_nat_ip,
-    );
+    let decision =
+        decide_network_capabilities(&config.network, &probe, config.general.middle_proxy_nat_ip);
     log_probe_result(&probe, &decision);
     startup_tracker
         .complete_component(
@@ -438,24 +475,16 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
 
     // If ME failed to initialize, force direct-only mode.
     if me_pool.is_some() {
-        startup_tracker
-            .set_transport_mode("middle_proxy")
-            .await;
-        startup_tracker
-            .set_degraded(false)
-            .await;
+        startup_tracker.set_transport_mode("middle_proxy").await;
+        startup_tracker.set_degraded(false).await;
         info!("Transport: Middle-End Proxy - all DC-over-RPC");
     } else {
         let _ = use_middle_proxy;
         use_middle_proxy = false;
         // Make runtime config reflect direct-only mode for handlers.
         config.general.use_middle_proxy = false;
-        startup_tracker
-            .set_transport_mode("direct")
-            .await;
-        startup_tracker
-            .set_degraded(true)
-            .await;
+        startup_tracker.set_transport_mode("direct").await;
+        startup_tracker.set_degraded(true).await;
         if me2dc_fallback {
             startup_tracker
                 .set_me_status(StartupMeStatus::Failed, "fallback_to_direct")

src/maestro/runtime_tasks.rs

@@ -1,24 +1,27 @@
 use std::net::IpAddr;
-use std::path::PathBuf;
+use std::path::Path;
 use std::sync::Arc;
 
 use tokio::sync::{mpsc, watch};
 use tracing::{debug, warn};
-use tracing_subscriber::reload;
 use tracing_subscriber::EnvFilter;
+use tracing_subscriber::reload;
 
-use crate::config::{LogLevel, ProxyConfig};
 use crate::config::hot_reload::spawn_config_watcher;
+use crate::config::{LogLevel, ProxyConfig};
 use crate::crypto::SecureRandom;
 use crate::ip_tracker::UserIpTracker;
 use crate::metrics;
 use crate::network::probe::NetworkProbe;
-use crate::startup::{COMPONENT_CONFIG_WATCHER_START, COMPONENT_METRICS_START, COMPONENT_RUNTIME_READY, StartupTracker};
+use crate::startup::{
+    COMPONENT_CONFIG_WATCHER_START, COMPONENT_METRICS_START, COMPONENT_RUNTIME_READY,
+    StartupTracker,
+};
 use crate::stats::beobachten::BeobachtenStore;
 use crate::stats::telemetry::TelemetryPolicy;
 use crate::stats::{ReplayChecker, Stats};
-use crate::transport::middle_proxy::{MePool, MeReinitTrigger};
 use crate::transport::UpstreamManager;
+use crate::transport::middle_proxy::{MePool, MeReinitTrigger};
 
 use super::helpers::write_beobachten_snapshot;
 
@@ -32,7 +35,7 @@ pub(crate) struct RuntimeWatches {
 #[allow(clippy::too_many_arguments)]
 pub(crate) async fn spawn_runtime_tasks(
     config: &Arc<ProxyConfig>,
-    config_path: &str,
+    config_path: &Path,
     probe: &NetworkProbe,
     prefer_ipv6: bool,
     decision_ipv4_dc: bool,
@@ -79,11 +82,9 @@ pub(crate) async fn spawn_runtime_tasks(
             Some("spawn config hot-reload watcher".to_string()),
         )
         .await;
-    let (config_rx, log_level_rx): (
-        watch::Receiver<Arc<ProxyConfig>>,
-        watch::Receiver<LogLevel>,
-    ) = spawn_config_watcher(
-        PathBuf::from(config_path),
+    let (config_rx, log_level_rx): (watch::Receiver<Arc<ProxyConfig>>, watch::Receiver<LogLevel>) =
+        spawn_config_watcher(
+            config_path.to_path_buf(),
             config.clone(),
             detected_ip_v4,
             detected_ip_v6,
@@ -114,7 +115,8 @@ pub(crate) async fn spawn_runtime_tasks(
                 break;
             }
             let cfg = config_rx_policy.borrow_and_update().clone();
-            stats_policy.apply_telemetry_policy(TelemetryPolicy::from_config(&cfg.general.telemetry));
+            stats_policy
+                .apply_telemetry_policy(TelemetryPolicy::from_config(&cfg.general.telemetry));
             if let Some(pool) = &me_pool_for_policy {
                 pool.update_runtime_transport_policy(
                     cfg.general.me_socks_kdf_policy,
@@ -130,7 +132,11 @@ pub(crate) async fn spawn_runtime_tasks(
     let ip_tracker_policy = ip_tracker.clone();
     let mut config_rx_ip_limits = config_rx.clone();
     tokio::spawn(async move {
-        let mut prev_limits = config_rx_ip_limits.borrow().access.user_max_unique_ips.clone();
+        let mut prev_limits = config_rx_ip_limits
+            .borrow()
+            .access
+            .user_max_unique_ips
+            .clone();
         let mut prev_global_each = config_rx_ip_limits
             .borrow()
             .access
@@ -183,7 +189,9 @@ pub(crate) async fn spawn_runtime_tasks(
             let sleep_secs = cfg.general.beobachten_flush_secs.max(1);
 
             if cfg.general.beobachten {
-                let ttl = std::time::Duration::from_secs(cfg.general.beobachten_minutes.saturating_mul(60));
+                let ttl = std::time::Duration::from_secs(
+                    cfg.general.beobachten_minutes.saturating_mul(60),
+                );
                 let path = cfg.general.beobachten_file.clone();
                 let snapshot = beobachten_writer.snapshot_text(ttl);
                 if let Err(e) = write_beobachten_snapshot(&path, &snapshot).await {
@@ -227,7 +235,10 @@ pub(crate) async fn spawn_runtime_tasks(
         let config_rx_clone_rot = config_rx.clone();
         let reinit_tx_rotation = reinit_tx.clone();
         tokio::spawn(async move {
-            crate::transport::middle_proxy::me_rotation_task(config_rx_clone_rot, reinit_tx_rotation)
+            crate::transport::middle_proxy::me_rotation_task(
+                config_rx_clone_rot,
+                reinit_tx_rotation,
+            )
             .await;
         });
     }

src/maestro/shutdown.rs

@@ -16,7 +16,10 @@ pub(crate) async fn wait_for_shutdown(process_started_at: Instant, me_pool: Opti
             let uptime_secs = process_started_at.elapsed().as_secs();
             info!("Uptime: {}", format_uptime(uptime_secs));
             if let Some(pool) = &me_pool {
-                match tokio::time::timeout(Duration::from_secs(2), pool.shutdown_send_close_conn_all())
+                match tokio::time::timeout(
+                    Duration::from_secs(2),
+                    pool.shutdown_send_close_conn_all(),
+                )
                 .await
                 {
                     Ok(total) => {

src/maestro/tls_bootstrap.rs

@@ -1,12 +1,13 @@
 use std::sync::Arc;
 use std::time::Duration;
 
-use rand::Rng;
+use rand::RngExt;
 use tracing::warn;
 
 use crate::config::ProxyConfig;
 use crate::startup::{COMPONENT_TLS_FRONT_BOOTSTRAP, StartupTracker};
 use crate::tls_front::TlsFrontCache;
+use crate::tls_front::fetcher::TlsFetchStrategy;
 use crate::transport::UpstreamManager;
 
 pub(crate) async fn bootstrap_tls_front(
@@ -40,7 +41,17 @@ pub(crate) async fn bootstrap_tls_front(
         let mask_unix_sock = config.censorship.mask_unix_sock.clone();
         let tls_fetch_scope = (!config.censorship.tls_fetch_scope.is_empty())
             .then(|| config.censorship.tls_fetch_scope.clone());
-        let fetch_timeout = Duration::from_secs(5);
+        let tls_fetch = config.censorship.tls_fetch.clone();
+        let fetch_strategy = TlsFetchStrategy {
+            profiles: tls_fetch.profiles,
+            strict_route: tls_fetch.strict_route,
+            attempt_timeout: Duration::from_millis(tls_fetch.attempt_timeout_ms.max(1)),
+            total_budget: Duration::from_millis(tls_fetch.total_budget_ms.max(1)),
+            grease_enabled: tls_fetch.grease_enabled,
+            deterministic: tls_fetch.deterministic,
+            profile_cache_ttl: Duration::from_secs(tls_fetch.profile_cache_ttl_secs),
+        };
+        let fetch_timeout = fetch_strategy.total_budget;
 
         let cache_initial = cache.clone();
         let domains_initial = tls_domains.to_vec();
@@ -48,6 +59,7 @@ pub(crate) async fn bootstrap_tls_front(
         let unix_sock_initial = mask_unix_sock.clone();
         let scope_initial = tls_fetch_scope.clone();
         let upstream_initial = upstream_manager.clone();
+        let strategy_initial = fetch_strategy.clone();
         tokio::spawn(async move {
             let mut join = tokio::task::JoinSet::new();
             for domain in domains_initial {
@@ -56,12 +68,13 @@ pub(crate) async fn bootstrap_tls_front(
                 let unix_sock_domain = unix_sock_initial.clone();
                 let scope_domain = scope_initial.clone();
                 let upstream_domain = upstream_initial.clone();
+                let strategy_domain = strategy_initial.clone();
                 join.spawn(async move {
-                    match crate::tls_front::fetcher::fetch_real_tls(
+                    match crate::tls_front::fetcher::fetch_real_tls_with_strategy(
                         &host_domain,
                         port,
                         &domain,
-                        fetch_timeout,
+                        &strategy_domain,
                         Some(upstream_domain),
                         scope_domain.as_deref(),
                         proxy_protocol,
@@ -107,6 +120,7 @@ pub(crate) async fn bootstrap_tls_front(
         let unix_sock_refresh = mask_unix_sock.clone();
         let scope_refresh = tls_fetch_scope.clone();
         let upstream_refresh = upstream_manager.clone();
+        let strategy_refresh = fetch_strategy.clone();
         tokio::spawn(async move {
             loop {
                 let base_secs = rand::rng().random_range(4 * 3600..=6 * 3600);
@@ -120,12 +134,13 @@ pub(crate) async fn bootstrap_tls_front(
                     let unix_sock_domain = unix_sock_refresh.clone();
                     let scope_domain = scope_refresh.clone();
                     let upstream_domain = upstream_refresh.clone();
+                    let strategy_domain = strategy_refresh.clone();
                     join.spawn(async move {
-                        match crate::tls_front::fetcher::fetch_real_tls(
+                        match crate::tls_front::fetcher::fetch_real_tls_with_strategy(
                             &host_domain,
                             port,
                             &domain,
-                            fetch_timeout,
+                            &strategy_domain,
                             Some(upstream_domain),
                             scope_domain.as_deref(),
                             proxy_protocol,

src/main.rs

@@ -7,6 +7,13 @@ mod crypto;
 mod error;
 mod ip_tracker;
 #[cfg(test)]
+#[path = "tests/ip_tracker_encapsulation_adversarial_tests.rs"]
+mod ip_tracker_encapsulation_adversarial_tests;
+#[cfg(test)]
+#[path = "tests/ip_tracker_hotpath_adversarial_tests.rs"]
+mod ip_tracker_hotpath_adversarial_tests;
+#[cfg(test)]
+#[path = "tests/ip_tracker_regression_tests.rs"]
 mod ip_tracker_regression_tests;
 mod maestro;
 mod metrics;
@@ -22,5 +29,6 @@ mod util;
 
 #[tokio::main]
 async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
+    let _ = rustls::crypto::ring::default_provider().install_default();
     maestro::run().await
 }

src/network/dns_overrides.rs

@@ -26,9 +26,7 @@ fn parse_ip_spec(ip_spec: &str) -> Result<IpAddr> {
     }
 
     let ip = ip_spec.parse::<IpAddr>().map_err(|_| {
-        ProxyError::Config(format!(
-            "network.dns_overrides IP is invalid: '{ip_spec}'"
-        ))
+        ProxyError::Config(format!("network.dns_overrides IP is invalid: '{ip_spec}'"))
     })?;
     if matches!(ip, IpAddr::V6(_)) {
         return Err(ProxyError::Config(format!(
@@ -103,9 +101,9 @@ pub fn validate_entries(entries: &[String]) -> Result<()> {
 /// Replace runtime DNS overrides with a new validated snapshot.
 pub fn install_entries(entries: &[String]) -> Result<()> {
     let parsed = parse_entries(entries)?;
-    let mut guard = overrides_store()
-        .write()
-        .map_err(|_| ProxyError::Config("network.dns_overrides runtime lock is poisoned".to_string()))?;
+    let mut guard = overrides_store().write().map_err(|_| {
+        ProxyError::Config("network.dns_overrides runtime lock is poisoned".to_string())
+    })?;
     *guard = parsed;
     Ok(())
 }

src/network/probe.rs

@@ -1,4 +1,5 @@
 #![allow(dead_code)]
+#![allow(clippy::items_after_test_module)]
 
 use std::collections::HashMap;
 use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, UdpSocket};
@@ -10,7 +11,9 @@ use tracing::{debug, info, warn};
 
 use crate::config::{NetworkConfig, UpstreamConfig, UpstreamType};
 use crate::error::Result;
-use crate::network::stun::{stun_probe_family_with_bind, DualStunResult, IpFamily, StunProbeResult};
+use crate::network::stun::{
+    DualStunResult, IpFamily, StunProbeResult, stun_probe_family_with_bind,
+};
 use crate::transport::UpstreamManager;
 
 #[derive(Debug, Clone, Default)]
@@ -78,12 +81,7 @@ pub async fn run_probe(
             warn!("STUN probe is enabled but network.stun_servers is empty");
             DualStunResult::default()
         } else {
-            probe_stun_servers_parallel(
-                &servers,
-                stun_nat_probe_concurrency.max(1),
-                None,
-                None,
-            )
+            probe_stun_servers_parallel(&servers, stun_nat_probe_concurrency.max(1), None, None)
                 .await
         }
     } else if nat_probe {
@@ -99,7 +97,8 @@ pub async fn run_probe(
         let UpstreamType::Direct {
             interface,
             bind_addresses,
-        } = &upstream.upstream_type else {
+        } = &upstream.upstream_type
+        else {
             continue;
         };
         if let Some(addrs) = bind_addresses.as_ref().filter(|v| !v.is_empty()) {
@@ -199,12 +198,11 @@ pub async fn run_probe(
     if nat_probe
         && probe.reflected_ipv4.is_none()
         && probe.detected_ipv4.map(is_bogon_v4).unwrap_or(false)
+        && let Some(public_ip) = detect_public_ipv4_http(&config.http_ip_detect_urls).await
     {
-        if let Some(public_ip) = detect_public_ipv4_http(&config.http_ip_detect_urls).await {
         probe.reflected_ipv4 = Some(SocketAddr::new(IpAddr::V4(public_ip), 0));
         info!(public_ip = %public_ip, "STUN unavailable, using HTTP public IPv4 fallback");
     }
-    }
 
     probe.ipv4_nat_detected = match (probe.detected_ipv4, probe.reflected_ipv4) {
         (Some(det), Some(reflected)) => det != reflected.ip(),
@@ -217,12 +215,20 @@ pub async fn run_probe(
 
     probe.ipv4_usable = config.ipv4
         && probe.detected_ipv4.is_some()
-        && (!probe.ipv4_is_bogon || probe.reflected_ipv4.map(|r| !is_bogon(r.ip())).unwrap_or(false));
+        && (!probe.ipv4_is_bogon
+            || probe
+                .reflected_ipv4
+                .map(|r| !is_bogon(r.ip()))
+                .unwrap_or(false));
 
     let ipv6_enabled = config.ipv6.unwrap_or(probe.detected_ipv6.is_some());
     probe.ipv6_usable = ipv6_enabled
         && probe.detected_ipv6.is_some()
-        && (!probe.ipv6_is_bogon || probe.reflected_ipv6.map(|r| !is_bogon(r.ip())).unwrap_or(false));
+        && (!probe.ipv6_is_bogon
+            || probe
+                .reflected_ipv6
+                .map(|r| !is_bogon(r.ip()))
+                .unwrap_or(false));
 
     Ok(probe)
 }
@@ -280,8 +286,6 @@ async fn probe_stun_servers_parallel(
         while next_idx < servers.len() && join_set.len() < concurrency {
             let stun_addr = servers[next_idx].clone();
             next_idx += 1;
-            let bind_v4 = bind_v4;
-            let bind_v6 = bind_v6;
             join_set.spawn(async move {
                 let res = timeout(STUN_BATCH_TIMEOUT, async {
                     let v4 = stun_probe_family_with_bind(&stun_addr, IpFamily::V4, bind_v4).await?;
@@ -300,11 +304,15 @@ async fn probe_stun_servers_parallel(
         match task {
             Ok((stun_addr, Ok(Ok(result)))) => {
                 if let Some(v4) = result.v4 {
-                    let entry = best_v4_by_ip.entry(v4.reflected_addr.ip()).or_insert((0, v4));
+                    let entry = best_v4_by_ip
+                        .entry(v4.reflected_addr.ip())
+                        .or_insert((0, v4));
                     entry.0 += 1;
                 }
                 if let Some(v6) = result.v6 {
-                    let entry = best_v6_by_ip.entry(v6.reflected_addr.ip()).or_insert((0, v6));
+                    let entry = best_v6_by_ip
+                        .entry(v6.reflected_addr.ip())
+                        .or_insert((0, v6));
                     entry.0 += 1;
                 }
                 if result.v4.is_some() || result.v6.is_some() {
@@ -324,17 +332,11 @@ async fn probe_stun_servers_parallel(
     }
 
     let mut out = DualStunResult::default();
-    if let Some((_, best)) = best_v4_by_ip
-        .into_values()
-        .max_by_key(|(count, _)| *count)
-    {
+    if let Some((_, best)) = best_v4_by_ip.into_values().max_by_key(|(count, _)| *count) {
         info!("STUN-Quorum reached, IP: {}", best.reflected_addr.ip());
         out.v4 = Some(best);
     }
-    if let Some((_, best)) = best_v6_by_ip
-        .into_values()
-        .max_by_key(|(count, _)| *count)
-    {
+    if let Some((_, best)) = best_v6_by_ip.into_values().max_by_key(|(count, _)| *count) {
         info!("STUN-Quorum reached, IP: {}", best.reflected_addr.ip());
         out.v6 = Some(best);
     }
@@ -347,7 +349,8 @@ pub fn decide_network_capabilities(
     middle_proxy_nat_ip: Option<IpAddr>,
 ) -> NetworkDecision {
     let ipv4_dc = config.ipv4 && probe.detected_ipv4.is_some();
-    let ipv6_dc = config.ipv6.unwrap_or(probe.detected_ipv6.is_some()) && probe.detected_ipv6.is_some();
+    let ipv6_dc =
+        config.ipv6.unwrap_or(probe.detected_ipv6.is_some()) && probe.detected_ipv6.is_some();
     let nat_ip_v4 = matches!(middle_proxy_nat_ip, Some(IpAddr::V4(_)));
     let nat_ip_v6 = matches!(middle_proxy_nat_ip, Some(IpAddr::V6(_)));
 
@@ -534,10 +537,26 @@ pub fn is_bogon_v6(ip: Ipv6Addr) -> bool {
 
 pub fn log_probe_result(probe: &NetworkProbe, decision: &NetworkDecision) {
     info!(
-        ipv4 = probe.detected_ipv4.as_ref().map(|v| v.to_string()).unwrap_or_else(|| "-".into()),
-        ipv6 = probe.detected_ipv6.as_ref().map(|v| v.to_string()).unwrap_or_else(|| "-".into()),
-        reflected_v4 = probe.reflected_ipv4.as_ref().map(|v| v.ip().to_string()).unwrap_or_else(|| "-".into()),
-        reflected_v6 = probe.reflected_ipv6.as_ref().map(|v| v.ip().to_string()).unwrap_or_else(|| "-".into()),
+        ipv4 = probe
+            .detected_ipv4
+            .as_ref()
+            .map(|v| v.to_string())
+            .unwrap_or_else(|| "-".into()),
+        ipv6 = probe
+            .detected_ipv6
+            .as_ref()
+            .map(|v| v.to_string())
+            .unwrap_or_else(|| "-".into()),
+        reflected_v4 = probe
+            .reflected_ipv4
+            .as_ref()
+            .map(|v| v.ip().to_string())
+            .unwrap_or_else(|| "-".into()),
+        reflected_v6 = probe
+            .reflected_ipv6
+            .as_ref()
+            .map(|v| v.ip().to_string())
+            .unwrap_or_else(|| "-".into()),
         ipv4_bogon = probe.ipv4_is_bogon,
         ipv6_bogon = probe.ipv6_is_bogon,
         ipv4_me = decision.ipv4_me,

src/network/stun.rs

@@ -2,13 +2,20 @@
 #![allow(dead_code)]
 
 use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
+use std::sync::OnceLock;
 
-use tokio::net::{lookup_host, UdpSocket};
-use tokio::time::{timeout, Duration, sleep};
+use tokio::net::{UdpSocket, lookup_host};
+use tokio::time::{Duration, sleep, timeout};
 
+use crate::crypto::SecureRandom;
 use crate::error::{ProxyError, Result};
 use crate::network::dns_overrides::{resolve, split_host_port};
 
+fn stun_rng() -> &'static SecureRandom {
+    static STUN_RNG: OnceLock<SecureRandom> = OnceLock::new();
+    STUN_RNG.get_or_init(SecureRandom::new)
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum IpFamily {
     V4,
@@ -34,13 +41,13 @@ pub async fn stun_probe_dual(stun_addr: &str) -> Result<DualStunResult> {
         stun_probe_family(stun_addr, IpFamily::V6),
     );
 
-    Ok(DualStunResult {
-        v4: v4?,
-        v6: v6?,
-    })
+    Ok(DualStunResult { v4: v4?, v6: v6? })
 }
 
-pub async fn stun_probe_family(stun_addr: &str, family: IpFamily) -> Result<Option<StunProbeResult>> {
+pub async fn stun_probe_family(
+    stun_addr: &str,
+    family: IpFamily,
+) -> Result<Option<StunProbeResult>> {
     stun_probe_family_with_bind(stun_addr, family, None).await
 }
 
@@ -49,8 +56,6 @@ pub async fn stun_probe_family_with_bind(
     family: IpFamily,
     bind_ip: Option<IpAddr>,
 ) -> Result<Option<StunProbeResult>> {
-    use rand::RngCore;
-
     let bind_addr = match (family, bind_ip) {
         (IpFamily::V4, Some(IpAddr::V4(ip))) => SocketAddr::new(IpAddr::V4(ip), 0),
         (IpFamily::V6, Some(IpAddr::V6(ip))) => SocketAddr::new(IpAddr::V6(ip), 0),
@@ -71,13 +76,18 @@ pub async fn stun_probe_family_with_bind(
     if let Some(addr) = target_addr {
         match socket.connect(addr).await {
             Ok(()) => {}
-            Err(e) if family == IpFamily::V6 && matches!(
+            Err(e)
+                if family == IpFamily::V6
+                    && matches!(
                         e.kind(),
                         std::io::ErrorKind::NetworkUnreachable
                             | std::io::ErrorKind::HostUnreachable
                             | std::io::ErrorKind::Unsupported
                             | std::io::ErrorKind::NetworkDown
-            ) => return Ok(None),
+                    ) =>
+            {
+                return Ok(None);
+            }
             Err(e) => return Err(ProxyError::Proxy(format!("STUN connect failed: {e}"))),
         }
     } else {
@@ -88,7 +98,7 @@ pub async fn stun_probe_family_with_bind(
     req[0..2].copy_from_slice(&0x0001u16.to_be_bytes()); // Binding Request
     req[2..4].copy_from_slice(&0u16.to_be_bytes()); // length
     req[4..8].copy_from_slice(&0x2112A442u32.to_be_bytes()); // magic cookie
-    rand::rng().fill_bytes(&mut req[8..20]); // transaction ID
+    stun_rng().fill(&mut req[8..20]); // transaction ID
 
     let mut buf = [0u8; 256];
     let mut attempt = 0;
@@ -200,7 +210,6 @@ pub async fn stun_probe_family_with_bind(
 
             idx += (alen + 3) & !3;
         }
-
     }
 
     Ok(None)
@@ -228,7 +237,11 @@ async fn resolve_stun_addr(stun_addr: &str, family: IpFamily) -> Result<Option<S
         .await
         .map_err(|e| ProxyError::Proxy(format!("STUN resolve failed: {e}")))?;
 
-    let target = addrs
-        .find(|a| matches!((a.is_ipv4(), family), (true, IpFamily::V4) | (false, IpFamily::V6)));
+    let target = addrs.find(|a| {
+        matches!(
+            (a.is_ipv4(), family),
+            (true, IpFamily::V4) | (false, IpFamily::V6)
+        )
+    });
     Ok(target)
 }

src/protocol/constants.rs

@@ -36,32 +36,86 @@ pub static TG_DATACENTERS_V6: LazyLock<Vec<IpAddr>> = LazyLock::new(|| {
 pub static TG_MIDDLE_PROXIES_V4: LazyLock<std::collections::HashMap<i32, Vec<(IpAddr, u16)>>> =
     LazyLock::new(|| {
         let mut m = std::collections::HashMap::new();
-        m.insert(1, vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 175, 50)), 8888)]);
-        m.insert(-1, vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 175, 50)), 8888)]);
-        m.insert(2, vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 161, 144)), 8888)]);
-        m.insert(-2, vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 161, 144)), 8888)]);
-        m.insert(3, vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 175, 100)), 8888)]);
-        m.insert(-3, vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 175, 100)), 8888)]);
+        m.insert(
+            1,
+            vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 175, 50)), 8888)],
+        );
+        m.insert(
+            -1,
+            vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 175, 50)), 8888)],
+        );
+        m.insert(
+            2,
+            vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 161, 144)), 8888)],
+        );
+        m.insert(
+            -2,
+            vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 161, 144)), 8888)],
+        );
+        m.insert(
+            3,
+            vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 175, 100)), 8888)],
+        );
+        m.insert(
+            -3,
+            vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 175, 100)), 8888)],
+        );
         m.insert(4, vec![(IpAddr::V4(Ipv4Addr::new(91, 108, 4, 136)), 8888)]);
-        m.insert(-4, vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 165, 109)), 8888)]);
+        m.insert(
+            -4,
+            vec![(IpAddr::V4(Ipv4Addr::new(149, 154, 165, 109)), 8888)],
+        );
         m.insert(5, vec![(IpAddr::V4(Ipv4Addr::new(91, 108, 56, 183)), 8888)]);
-        m.insert(-5, vec![(IpAddr::V4(Ipv4Addr::new(91, 108, 56, 183)), 8888)]);
+        m.insert(
+            -5,
+            vec![(IpAddr::V4(Ipv4Addr::new(91, 108, 56, 183)), 8888)],
+        );
         m
     });
 
 pub static TG_MIDDLE_PROXIES_V6: LazyLock<std::collections::HashMap<i32, Vec<(IpAddr, u16)>>> =
     LazyLock::new(|| {
         let mut m = std::collections::HashMap::new();
-        m.insert(1, vec![(IpAddr::V6("2001:b28:f23d:f001::d".parse().unwrap()), 8888)]);
-        m.insert(-1, vec![(IpAddr::V6("2001:b28:f23d:f001::d".parse().unwrap()), 8888)]);
-        m.insert(2, vec![(IpAddr::V6("2001:67c:04e8:f002::d".parse().unwrap()), 80)]);
-        m.insert(-2, vec![(IpAddr::V6("2001:67c:04e8:f002::d".parse().unwrap()), 80)]);
-        m.insert(3, vec![(IpAddr::V6("2001:b28:f23d:f003::d".parse().unwrap()), 8888)]);
-        m.insert(-3, vec![(IpAddr::V6("2001:b28:f23d:f003::d".parse().unwrap()), 8888)]);
-        m.insert(4, vec![(IpAddr::V6("2001:67c:04e8:f004::d".parse().unwrap()), 8888)]);
-        m.insert(-4, vec![(IpAddr::V6("2001:67c:04e8:f004::d".parse().unwrap()), 8888)]);
-        m.insert(5, vec![(IpAddr::V6("2001:b28:f23f:f005::d".parse().unwrap()), 8888)]);
-        m.insert(-5, vec![(IpAddr::V6("2001:b28:f23f:f005::d".parse().unwrap()), 8888)]);
+        m.insert(
+            1,
+            vec![(IpAddr::V6("2001:b28:f23d:f001::d".parse().unwrap()), 8888)],
+        );
+        m.insert(
+            -1,
+            vec![(IpAddr::V6("2001:b28:f23d:f001::d".parse().unwrap()), 8888)],
+        );
+        m.insert(
+            2,
+            vec![(IpAddr::V6("2001:67c:04e8:f002::d".parse().unwrap()), 80)],
+        );
+        m.insert(
+            -2,
+            vec![(IpAddr::V6("2001:67c:04e8:f002::d".parse().unwrap()), 80)],
+        );
+        m.insert(
+            3,
+            vec![(IpAddr::V6("2001:b28:f23d:f003::d".parse().unwrap()), 8888)],
+        );
+        m.insert(
+            -3,
+            vec![(IpAddr::V6("2001:b28:f23d:f003::d".parse().unwrap()), 8888)],
+        );
+        m.insert(
+            4,
+            vec![(IpAddr::V6("2001:67c:04e8:f004::d".parse().unwrap()), 8888)],
+        );
+        m.insert(
+            -4,
+            vec![(IpAddr::V6("2001:67c:04e8:f004::d".parse().unwrap()), 8888)],
+        );
+        m.insert(
+            5,
+            vec![(IpAddr::V6("2001:b28:f23f:f005::d".parse().unwrap()), 8888)],
+        );
+        m.insert(
+            -5,
+            vec![(IpAddr::V6("2001:b28:f23f:f005::d".parse().unwrap()), 8888)],
+        );
         m
     });
 
@@ -152,11 +206,29 @@ pub const TLS_RECORD_CHANGE_CIPHER: u8 = 0x14;
 pub const TLS_RECORD_APPLICATION: u8 = 0x17;
 /// TLS record type: Alert
 pub const TLS_RECORD_ALERT: u8 = 0x15;
-/// Maximum TLS record size
-pub const MAX_TLS_RECORD_SIZE: usize = 16384;
-/// Maximum TLS chunk size (with overhead)
-/// RFC 8446 §5.2 allows up to 16384 + 256 bytes of ciphertext
-pub const MAX_TLS_CHUNK_SIZE: usize = 16384 + 256;
+/// Maximum TLS plaintext record payload size.
+/// RFC 8446 §5.1: "The length MUST NOT exceed 2^14 bytes."
+/// Use this for validating incoming unencrypted records
+/// (ClientHello, ChangeCipherSpec, unprotected Handshake messages).
+pub const MAX_TLS_PLAINTEXT_SIZE: usize = 16_384;
+
+/// Structural minimum for a valid TLS 1.3 ClientHello with SNI.
+/// Derived from RFC 8446 §4.1.2 field layout + Appendix D.4 compat mode.
+/// Deliberately conservative (below any real client) to avoid false
+/// positives on legitimate connections with compact extension sets.
+pub const MIN_TLS_CLIENT_HELLO_SIZE: usize = 100;
+
+/// Maximum TLS ciphertext record payload size.
+/// RFC 8446 §5.2: "The length MUST NOT exceed 2^14 + 256 bytes."
+/// The +256 accounts for maximum AEAD expansion overhead.
+/// Use this for validating or sizing buffers for encrypted records.
+pub const MAX_TLS_CIPHERTEXT_SIZE: usize = 16_384 + 256;
+
+#[deprecated(note = "use MAX_TLS_PLAINTEXT_SIZE")]
+pub const MAX_TLS_RECORD_SIZE: usize = MAX_TLS_PLAINTEXT_SIZE;
+
+#[deprecated(note = "use MAX_TLS_CIPHERTEXT_SIZE")]
+pub const MAX_TLS_CHUNK_SIZE: usize = MAX_TLS_CIPHERTEXT_SIZE;
 
 /// Secure Intermediate payload is expected to be 4-byte aligned.
 pub fn is_valid_secure_payload_len(data_len: usize) -> bool {
@@ -204,9 +276,7 @@ pub const SMALL_BUFFER_SIZE: usize = 8192;
 // ============= Statistics =============
 
 /// Duration buckets for histogram metrics
-pub static DURATION_BUCKETS: &[f64] = &[
-    0.1, 0.5, 1.0, 2.0, 5.0, 15.0, 60.0, 300.0, 600.0, 1800.0,
-];
+pub static DURATION_BUCKETS: &[f64] = &[0.1, 0.5, 1.0, 2.0, 5.0, 15.0, 60.0, 300.0, 600.0, 1800.0];
 
 // ============= Reserved Nonce Patterns =============
 
@@ -224,9 +294,7 @@ pub static RESERVED_NONCE_BEGINNINGS: &[[u8; 4]] = &[
 ];
 
 /// Reserved continuation bytes (bytes 4-7)
-pub static RESERVED_NONCE_CONTINUES: &[[u8; 4]] = &[
-    [0x00, 0x00, 0x00, 0x00],
-];
+pub static RESERVED_NONCE_CONTINUES: &[[u8; 4]] = &[[0x00, 0x00, 0x00, 0x00]];
 
 // ============= RPC Constants (for Middle Proxy) =============
 
@@ -267,11 +335,10 @@ pub mod rpc_flags {
     pub const FLAG_QUICKACK: u32 = 0x80000000;
 }
 
+// ============= Middle-End Proxy Servers =============
+pub const ME_PROXY_PORT: u16 = 8888;
 
-    // ============= Middle-End Proxy Servers =============
-    pub const ME_PROXY_PORT: u16 = 8888;
-    
-    pub static TG_MIDDLE_PROXIES_FLAT_V4: LazyLock<Vec<(IpAddr, u16)>> = LazyLock::new(|| {
+pub static TG_MIDDLE_PROXIES_FLAT_V4: LazyLock<Vec<(IpAddr, u16)>> = LazyLock::new(|| {
     vec![
         (IpAddr::V4(Ipv4Addr::new(149, 154, 175, 50)), 8888),
         (IpAddr::V4(Ipv4Addr::new(149, 154, 161, 144)), 8888),
@@ -279,29 +346,29 @@ pub mod rpc_flags {
         (IpAddr::V4(Ipv4Addr::new(91, 108, 4, 136)), 8888),
         (IpAddr::V4(Ipv4Addr::new(91, 108, 56, 183)), 8888),
     ]
-    });
+});
 
-    // ============= RPC Constants (u32 native endian) =============
-    // From mtproto-common.h + net-tcp-rpc-common.h + mtproto-proxy.c
+// ============= RPC Constants (u32 native endian) =============
+// From mtproto-common.h + net-tcp-rpc-common.h + mtproto-proxy.c
 
-    pub const RPC_NONCE_U32: u32           = 0x7acb87aa;
-    pub const RPC_HANDSHAKE_U32: u32       = 0x7682eef5;
-    pub const RPC_HANDSHAKE_ERROR_U32: u32 = 0x6a27beda;
-    pub const TL_PROXY_TAG_U32: u32        = 0xdb1e26ae;  // mtproto-proxy.c:121
+pub const RPC_NONCE_U32: u32 = 0x7acb87aa;
+pub const RPC_HANDSHAKE_U32: u32 = 0x7682eef5;
+pub const RPC_HANDSHAKE_ERROR_U32: u32 = 0x6a27beda;
+pub const TL_PROXY_TAG_U32: u32 = 0xdb1e26ae; // mtproto-proxy.c:121
 
-    // mtproto-common.h
-    pub const RPC_PROXY_REQ_U32: u32       = 0x36cef1ee;
-    pub const RPC_PROXY_ANS_U32: u32       = 0x4403da0d;
-    pub const RPC_CLOSE_CONN_U32: u32      = 0x1fcf425d;
-    pub const RPC_CLOSE_EXT_U32: u32       = 0x5eb634a2;
-    pub const RPC_SIMPLE_ACK_U32: u32      = 0x3bac409b;
-    pub const RPC_PING_U32: u32            = 0x5730a2df;
-    pub const RPC_PONG_U32: u32            = 0x8430eaa7;
+// mtproto-common.h
+pub const RPC_PROXY_REQ_U32: u32 = 0x36cef1ee;
+pub const RPC_PROXY_ANS_U32: u32 = 0x4403da0d;
+pub const RPC_CLOSE_CONN_U32: u32 = 0x1fcf425d;
+pub const RPC_CLOSE_EXT_U32: u32 = 0x5eb634a2;
+pub const RPC_SIMPLE_ACK_U32: u32 = 0x3bac409b;
+pub const RPC_PING_U32: u32 = 0x5730a2df;
+pub const RPC_PONG_U32: u32 = 0x8430eaa7;
 
-    pub const RPC_CRYPTO_NONE_U32: u32 = 0;
-    pub const RPC_CRYPTO_AES_U32: u32  = 1;
+pub const RPC_CRYPTO_NONE_U32: u32 = 0;
+pub const RPC_CRYPTO_AES_U32: u32 = 1;
 
-    pub mod proxy_flags {
+pub mod proxy_flags {
     pub const FLAG_HAS_AD_TAG: u32 = 1;
     pub const FLAG_NOT_ENCRYPTED: u32 = 0x2;
     pub const FLAG_HAS_AD_TAG2: u32 = 0x8;
@@ -311,16 +378,20 @@ pub mod rpc_flags {
     pub const FLAG_INTERMEDIATE: u32 = 0x20000000;
     pub const FLAG_ABRIDGED: u32 = 0x40000000;
     pub const FLAG_QUICKACK: u32 = 0x80000000;
-    }
+}
 
-    pub mod rpc_crypto_flags {
+pub mod rpc_crypto_flags {
     pub const USE_CRC32C: u32 = 0x800;
-    }
+}
 
-    pub const ME_CONNECT_TIMEOUT_SECS: u64 = 5;
-    pub const ME_HANDSHAKE_TIMEOUT_SECS: u64 = 10;
+pub const ME_CONNECT_TIMEOUT_SECS: u64 = 5;
+pub const ME_HANDSHAKE_TIMEOUT_SECS: u64 = 10;
 
-    #[cfg(test)]
+#[cfg(test)]
+#[path = "tests/tls_size_constants_security_tests.rs"]
+mod tls_size_constants_security_tests;
+
+#[cfg(test)]
 mod tests {
     use super::*;
 

src/protocol/frame.rs

@@ -83,7 +83,7 @@ impl FrameMode {
 
 /// Validate message length for MTProto
 pub fn validate_message_length(len: usize) -> bool {
-    use super::constants::{MIN_MSG_LEN, MAX_MSG_LEN, PADDING_FILLER};
+    use super::constants::{MAX_MSG_LEN, MIN_MSG_LEN, PADDING_FILLER};
 
     (MIN_MSG_LEN..=MAX_MSG_LEN).contains(&len) && len.is_multiple_of(PADDING_FILLER.len())
 }

src/protocol/obfuscation.rs

@@ -2,9 +2,9 @@
 
 #![allow(dead_code)]
 
-use zeroize::Zeroize;
-use crate::crypto::{sha256, AesCtr};
 use super::constants::*;
+use crate::crypto::{AesCtr, sha256};
+use zeroize::Zeroize;
 
 /// Obfuscation parameters from handshake
 ///
@@ -69,9 +69,8 @@ impl ObfuscationParams {
                 None => continue,
             };
 
-            let dc_idx = i16::from_le_bytes(
-                decrypted[DC_IDX_POS..DC_IDX_POS + 2].try_into().unwrap()
-            );
+            let dc_idx =
+                i16::from_le_bytes(decrypted[DC_IDX_POS..DC_IDX_POS + 2].try_into().unwrap());
 
             let mut enc_key_input = Vec::with_capacity(PREKEY_LEN + secret.len());
             enc_key_input.extend_from_slice(enc_prekey);

src/protocol/tests/tls_adversarial_tests.rs

@@ -0,0 +1,358 @@
+use super::*;
+use crate::crypto::sha256_hmac;
+use std::time::Instant;
+
+/// Helper to create a byte vector of specific length.
+fn make_garbage(len: usize) -> Vec<u8> {
+    vec![0x42u8; len]
+}
+
+/// Helper to create a valid-looking HMAC digest for test.
+fn make_digest(secret: &[u8], msg: &[u8], ts: u32) -> [u8; 32] {
+    let mut hmac = sha256_hmac(secret, msg);
+    let ts_bytes = ts.to_le_bytes();
+    for i in 0..4 {
+        hmac[28 + i] ^= ts_bytes[i];
+    }
+    hmac
+}
+
+fn make_valid_tls_handshake_with_session_id(
+    secret: &[u8],
+    timestamp: u32,
+    session_id: &[u8],
+) -> Vec<u8> {
+    let session_id_len = session_id.len();
+    let len = TLS_DIGEST_POS + TLS_DIGEST_LEN + 1 + session_id_len;
+    let mut handshake = vec![0x42u8; len];
+
+    handshake[TLS_DIGEST_POS + TLS_DIGEST_LEN] = session_id_len as u8;
+    let sid_start = TLS_DIGEST_POS + TLS_DIGEST_LEN + 1;
+    handshake[sid_start..sid_start + session_id_len].copy_from_slice(session_id);
+    handshake[TLS_DIGEST_POS..TLS_DIGEST_POS + TLS_DIGEST_LEN].fill(0);
+
+    let digest = make_digest(secret, &handshake, timestamp);
+
+    handshake[TLS_DIGEST_POS..TLS_DIGEST_POS + TLS_DIGEST_LEN].copy_from_slice(&digest);
+    handshake
+}
+
+fn make_valid_tls_handshake(secret: &[u8], timestamp: u32) -> Vec<u8> {
+    make_valid_tls_handshake_with_session_id(secret, timestamp, &[0x42; 32])
+}
+
+// ------------------------------------------------------------------
+// Truncated Packet Tests (OWASP ASVS 5.1.4, 5.1.5)
+// ------------------------------------------------------------------
+
+#[test]
+fn validate_tls_handshake_truncated_10_bytes_rejected() {
+    let secrets = vec![("user".to_string(), b"secret".to_vec())];
+    let truncated = make_garbage(10);
+    assert!(validate_tls_handshake(&truncated, &secrets, true).is_none());
+}
+
+#[test]
+fn validate_tls_handshake_truncated_at_digest_start_rejected() {
+    let secrets = vec![("user".to_string(), b"secret".to_vec())];
+    // TLS_DIGEST_POS = 11. 11 bytes should be rejected.
+    let truncated = make_garbage(TLS_DIGEST_POS);
+    assert!(validate_tls_handshake(&truncated, &secrets, true).is_none());
+}
+
+#[test]
+fn validate_tls_handshake_truncated_inside_digest_rejected() {
+    let secrets = vec![("user".to_string(), b"secret".to_vec())];
+    // TLS_DIGEST_POS + 16 (half digest)
+    let truncated = make_garbage(TLS_DIGEST_POS + 16);
+    assert!(validate_tls_handshake(&truncated, &secrets, true).is_none());
+}
+
+#[test]
+fn extract_sni_truncated_at_record_header_rejected() {
+    let truncated = make_garbage(3);
+    assert!(extract_sni_from_client_hello(&truncated).is_none());
+}
+
+#[test]
+fn extract_sni_truncated_at_handshake_header_rejected() {
+    let mut truncated = vec![TLS_RECORD_HANDSHAKE, 0x03, 0x03, 0x00, 0x05];
+    truncated.extend_from_slice(&[0x01, 0x00]); // ClientHello type but truncated length
+    assert!(extract_sni_from_client_hello(&truncated).is_none());
+}
+
+// ------------------------------------------------------------------
+// Malformed Extension Parsing Tests
+// ------------------------------------------------------------------
+
+#[test]
+fn extract_sni_with_overlapping_extension_lengths_rejected() {
+    let mut h = vec![0x16, 0x03, 0x03, 0x00, 0x60]; // Record header
+    h.push(0x01); // Handshake type: ClientHello
+    h.extend_from_slice(&[0x00, 0x00, 0x5C]); // Length: 92
+    h.extend_from_slice(&[0x03, 0x03]); // Version
+    h.extend_from_slice(&[0u8; 32]); // Random
+    h.push(0); // Session ID length: 0
+    h.extend_from_slice(&[0x00, 0x02, 0x13, 0x01]); // Cipher suites
+    h.extend_from_slice(&[0x01, 0x00]); // Compression
+
+    // Extensions start
+    h.extend_from_slice(&[0x00, 0x20]); // Total Extensions length: 32
+
+    // Extension 1: SNI (type 0)
+    h.extend_from_slice(&[0x00, 0x00]);
+    h.extend_from_slice(&[0x00, 0x40]); // Claimed len: 64 (OVERFLOWS total extensions len 32)
+    h.extend_from_slice(&[0u8; 64]);
+
+    assert!(extract_sni_from_client_hello(&h).is_none());
+}
+
+#[test]
+fn extract_sni_with_infinite_loop_potential_extension_rejected() {
+    let mut h = vec![0x16, 0x03, 0x03, 0x00, 0x60]; // Record header
+    h.push(0x01); // Handshake type: ClientHello
+    h.extend_from_slice(&[0x00, 0x00, 0x5C]); // Length: 92
+    h.extend_from_slice(&[0x03, 0x03]); // Version
+    h.extend_from_slice(&[0u8; 32]); // Random
+    h.push(0); // Session ID length: 0
+    h.extend_from_slice(&[0x00, 0x02, 0x13, 0x01]); // Cipher suites
+    h.extend_from_slice(&[0x01, 0x00]); // Compression
+
+    // Extensions start
+    h.extend_from_slice(&[0x00, 0x10]); // Total Extensions length: 16
+
+    // Extension: zero length but claims more?
+    // If our parser didn't advance, it might loop.
+    // Telemt uses `pos += 4 + elen;` so it always advances.
+    h.extend_from_slice(&[0x12, 0x34]); // Unknown type
+    h.extend_from_slice(&[0x00, 0x00]); // Length 0
+
+    // Fill the rest with garbage
+    h.extend_from_slice(&[0x42; 12]);
+
+    // We expect it to finish without SNI found
+    assert!(extract_sni_from_client_hello(&h).is_none());
+}
+
+#[test]
+fn extract_sni_with_invalid_hostname_rejected() {
+    let host = b"invalid_host!%^";
+    let mut sni = Vec::new();
+    sni.extend_from_slice(&((host.len() + 3) as u16).to_be_bytes());
+    sni.push(0);
+    sni.extend_from_slice(&(host.len() as u16).to_be_bytes());
+    sni.extend_from_slice(host);
+
+    let mut h = vec![0x16, 0x03, 0x03, 0x00, 0x60]; // Record header
+    h.push(0x01); // ClientHello
+    h.extend_from_slice(&[0x00, 0x00, 0x5C]);
+    h.extend_from_slice(&[0x03, 0x03]);
+    h.extend_from_slice(&[0u8; 32]);
+    h.push(0);
+    h.extend_from_slice(&[0x00, 0x02, 0x13, 0x01]);
+    h.extend_from_slice(&[0x01, 0x00]);
+
+    let mut ext = Vec::new();
+    ext.extend_from_slice(&0x0000u16.to_be_bytes());
+    ext.extend_from_slice(&(sni.len() as u16).to_be_bytes());
+    ext.extend_from_slice(&sni);
+
+    h.extend_from_slice(&(ext.len() as u16).to_be_bytes());
+    h.extend_from_slice(&ext);
+
+    assert!(
+        extract_sni_from_client_hello(&h).is_none(),
+        "Invalid SNI hostname must be rejected"
+    );
+}
+
+// ------------------------------------------------------------------
+// Timing Neutrality Tests (OWASP ASVS 5.1.7)
+// ------------------------------------------------------------------
+
+#[test]
+fn validate_tls_handshake_timing_neutrality() {
+    let secret = b"timing_test_secret_32_bytes_long_";
+    let secrets = vec![("u".to_string(), secret.to_vec())];
+
+    let mut base = vec![0x42u8; 100];
+    base[TLS_DIGEST_POS + TLS_DIGEST_LEN] = 32;
+
+    const ITER: usize = 600;
+    const ROUNDS: usize = 7;
+
+    let mut per_round_avg_diff_ns = Vec::with_capacity(ROUNDS);
+
+    for round in 0..ROUNDS {
+        let mut success_h = base.clone();
+        let mut fail_h = base.clone();
+
+        let start_success = Instant::now();
+        for _ in 0..ITER {
+            let digest = make_digest(secret, &success_h, 0);
+            success_h[TLS_DIGEST_POS..TLS_DIGEST_POS + TLS_DIGEST_LEN].copy_from_slice(&digest);
+            let _ = validate_tls_handshake_at_time(&success_h, &secrets, true, 0);
+        }
+        let success_elapsed = start_success.elapsed();
+
+        let start_fail = Instant::now();
+        for i in 0..ITER {
+            let mut digest = make_digest(secret, &fail_h, 0);
+            let flip_idx = (i + round) % (TLS_DIGEST_LEN - 4);
+            digest[flip_idx] ^= 0xFF;
+            fail_h[TLS_DIGEST_POS..TLS_DIGEST_POS + TLS_DIGEST_LEN].copy_from_slice(&digest);
+            let _ = validate_tls_handshake_at_time(&fail_h, &secrets, true, 0);
+        }
+        let fail_elapsed = start_fail.elapsed();
+
+        let diff = if success_elapsed > fail_elapsed {
+            success_elapsed - fail_elapsed
+        } else {
+            fail_elapsed - success_elapsed
+        };
+        per_round_avg_diff_ns.push(diff.as_nanos() as f64 / ITER as f64);
+    }
+
+    per_round_avg_diff_ns.sort_by(|a, b| a.partial_cmp(b).unwrap());
+    let median_avg_diff_ns = per_round_avg_diff_ns[ROUNDS / 2];
+
+    // Keep this as a coarse side-channel guard only; noisy shared CI hosts can
+    // introduce microsecond-level jitter that should not fail deterministic suites.
+    assert!(
+        median_avg_diff_ns < 50_000.0,
+        "Median timing delta too large: {} ns/iter",
+        median_avg_diff_ns
+    );
+}
+
+// ------------------------------------------------------------------
+// Adversarial Fingerprinting / Active Probing Tests
+// ------------------------------------------------------------------
+
+#[test]
+fn is_tls_handshake_robustness_against_probing() {
+    // Valid TLS 1.0 ClientHello
+    assert!(is_tls_handshake(&[0x16, 0x03, 0x01]));
+    // Valid TLS 1.2/1.3 ClientHello (Legacy Record Layer)
+    assert!(is_tls_handshake(&[0x16, 0x03, 0x03]));
+
+    // Invalid record type but matching version
+    assert!(!is_tls_handshake(&[0x17, 0x03, 0x03]));
+    // Plaintext HTTP request
+    assert!(!is_tls_handshake(b"GET / HTTP/1.1"));
+    // Short garbage
+    assert!(!is_tls_handshake(&[0x16, 0x03]));
+}
+
+#[test]
+fn validate_tls_handshake_at_time_strict_boundary() {
+    let secret = b"strict_boundary_secret_32_bytes_";
+    let secrets = vec![("u".to_string(), secret.to_vec())];
+    let now: i64 = 1_000_000_000;
+
+    // Boundary: exactly TIME_SKEW_MAX (120s past)
+    let ts_past = (now - TIME_SKEW_MAX) as u32;
+    let h = make_valid_tls_handshake_with_session_id(secret, ts_past, &[0x42; 32]);
+    assert!(validate_tls_handshake_at_time(&h, &secrets, false, now).is_some());
+
+    // Boundary + 1s: should be rejected
+    let ts_too_past = (now - TIME_SKEW_MAX - 1) as u32;
+    let h2 = make_valid_tls_handshake_with_session_id(secret, ts_too_past, &[0x42; 32]);
+    assert!(validate_tls_handshake_at_time(&h2, &secrets, false, now).is_none());
+}
+
+#[test]
+fn extract_sni_with_duplicate_extensions_rejected() {
+    // Construct a ClientHello with TWO SNI extensions
+    let host1 = b"first.com";
+    let mut sni1 = Vec::new();
+    sni1.extend_from_slice(&((host1.len() + 3) as u16).to_be_bytes());
+    sni1.push(0);
+    sni1.extend_from_slice(&(host1.len() as u16).to_be_bytes());
+    sni1.extend_from_slice(host1);
+
+    let host2 = b"second.com";
+    let mut sni2 = Vec::new();
+    sni2.extend_from_slice(&((host2.len() + 3) as u16).to_be_bytes());
+    sni2.push(0);
+    sni2.extend_from_slice(&(host2.len() as u16).to_be_bytes());
+    sni2.extend_from_slice(host2);
+
+    let mut ext = Vec::new();
+    // Ext 1: SNI
+    ext.extend_from_slice(&0x0000u16.to_be_bytes());
+    ext.extend_from_slice(&(sni1.len() as u16).to_be_bytes());
+    ext.extend_from_slice(&sni1);
+    // Ext 2: SNI again
+    ext.extend_from_slice(&0x0000u16.to_be_bytes());
+    ext.extend_from_slice(&(sni2.len() as u16).to_be_bytes());
+    ext.extend_from_slice(&sni2);
+
+    let mut body = Vec::new();
+    body.extend_from_slice(&[0x03, 0x03]);
+    body.extend_from_slice(&[0u8; 32]);
+    body.push(0);
+    body.extend_from_slice(&[0x00, 0x02, 0x13, 0x01]);
+    body.extend_from_slice(&[0x01, 0x00]);
+    body.extend_from_slice(&(ext.len() as u16).to_be_bytes());
+    body.extend_from_slice(&ext);
+
+    let mut handshake = Vec::new();
+    handshake.push(0x01);
+    let body_len = (body.len() as u32).to_be_bytes();
+    handshake.extend_from_slice(&body_len[1..4]);
+    handshake.extend_from_slice(&body);
+
+    let mut h = Vec::new();
+    h.push(0x16);
+    h.extend_from_slice(&[0x03, 0x03]);
+    h.extend_from_slice(&(handshake.len() as u16).to_be_bytes());
+    h.extend_from_slice(&handshake);
+
+    // Duplicate SNI extensions are ambiguous and must fail closed.
+    assert!(extract_sni_from_client_hello(&h).is_none());
+}
+
+#[test]
+fn extract_alpn_with_malformed_list_rejected() {
+    let mut alpn_payload = Vec::new();
+    alpn_payload.extend_from_slice(&0x0005u16.to_be_bytes()); // Total len 5
+    alpn_payload.push(10); // Labeled len 10 (OVERFLOWS total 5)
+    alpn_payload.extend_from_slice(b"h2");
+
+    let mut ext = Vec::new();
+    ext.extend_from_slice(&0x0010u16.to_be_bytes()); // Type: ALPN (16)
+    ext.extend_from_slice(&(alpn_payload.len() as u16).to_be_bytes());
+    ext.extend_from_slice(&alpn_payload);
+
+    let mut h = vec![
+        0x16, 0x03, 0x03, 0x00, 0x40, 0x01, 0x00, 0x00, 0x3C, 0x03, 0x03,
+    ];
+    h.extend_from_slice(&[0u8; 32]);
+    h.push(0);
+    h.extend_from_slice(&[0x00, 0x02, 0x13, 0x01, 0x01, 0x00]);
+    h.extend_from_slice(&(ext.len() as u16).to_be_bytes());
+    h.extend_from_slice(&ext);
+
+    let res = extract_alpn_from_client_hello(&h);
+    assert!(
+        res.is_empty(),
+        "Malformed ALPN list must return empty or fail"
+    );
+}
+
+#[test]
+fn extract_sni_with_huge_extension_header_rejected() {
+    let mut h = vec![0x16, 0x03, 0x03, 0x00, 0x00]; // Record header
+    h.push(0x01); // ClientHello
+    h.extend_from_slice(&[0x00, 0xFF, 0xFF]); // Huge length (65535) - overflows record
+    h.extend_from_slice(&[0x03, 0x03]);
+    h.extend_from_slice(&[0u8; 32]);
+    h.push(0);
+    h.extend_from_slice(&[0x00, 0x02, 0x13, 0x01, 0x01, 0x00]);
+
+    // Extensions start
+    h.extend_from_slice(&[0xFF, 0xFF]); // Total extensions: 65535 (OVERFLOWS everything)
+
+    assert!(extract_sni_from_client_hello(&h).is_none());
+}

src/protocol/tests/tls_fuzz_security_tests.rs

@@ -0,0 +1,210 @@
+use super::*;
+use crate::crypto::sha256_hmac;
+use std::panic::catch_unwind;
+
+fn make_valid_tls_handshake_with_session_id(
+    secret: &[u8],
+    timestamp: u32,
+    session_id: &[u8],
+) -> Vec<u8> {
+    let session_id_len = session_id.len();
+    assert!(session_id_len <= u8::MAX as usize);
+
+    let len = TLS_DIGEST_POS + TLS_DIGEST_LEN + 1 + session_id_len;
+    let mut handshake = vec![0x42u8; len];
+    handshake[TLS_DIGEST_POS + TLS_DIGEST_LEN] = session_id_len as u8;
+    let sid_start = TLS_DIGEST_POS + TLS_DIGEST_LEN + 1;
+    handshake[sid_start..sid_start + session_id_len].copy_from_slice(session_id);
+    handshake[TLS_DIGEST_POS..TLS_DIGEST_POS + TLS_DIGEST_LEN].fill(0);
+
+    let mut digest = sha256_hmac(secret, &handshake);
+    let ts = timestamp.to_le_bytes();
+    for idx in 0..4 {
+        digest[28 + idx] ^= ts[idx];
+    }
+
+    handshake[TLS_DIGEST_POS..TLS_DIGEST_POS + TLS_DIGEST_LEN].copy_from_slice(&digest);
+    handshake
+}
+
+fn make_valid_client_hello_record(host: &str, alpn_protocols: &[&[u8]]) -> Vec<u8> {
+    let mut body = Vec::new();
+    body.extend_from_slice(&TLS_VERSION);
+    body.extend_from_slice(&[0u8; 32]);
+    body.push(0);
+    body.extend_from_slice(&2u16.to_be_bytes());
+    body.extend_from_slice(&[0x13, 0x01]);
+    body.push(1);
+    body.push(0);
+
+    let mut ext_blob = Vec::new();
+
+    let host_bytes = host.as_bytes();
+    let mut sni_payload = Vec::new();
+    sni_payload.extend_from_slice(&((host_bytes.len() + 3) as u16).to_be_bytes());
+    sni_payload.push(0);
+    sni_payload.extend_from_slice(&(host_bytes.len() as u16).to_be_bytes());
+    sni_payload.extend_from_slice(host_bytes);
+    ext_blob.extend_from_slice(&0x0000u16.to_be_bytes());
+    ext_blob.extend_from_slice(&(sni_payload.len() as u16).to_be_bytes());
+    ext_blob.extend_from_slice(&sni_payload);
+
+    if !alpn_protocols.is_empty() {
+        let mut alpn_list = Vec::new();
+        for proto in alpn_protocols {
+            alpn_list.push(proto.len() as u8);
+            alpn_list.extend_from_slice(proto);
+        }
+        let mut alpn_data = Vec::new();
+        alpn_data.extend_from_slice(&(alpn_list.len() as u16).to_be_bytes());
+        alpn_data.extend_from_slice(&alpn_list);
+
+        ext_blob.extend_from_slice(&0x0010u16.to_be_bytes());
+        ext_blob.extend_from_slice(&(alpn_data.len() as u16).to_be_bytes());
+        ext_blob.extend_from_slice(&alpn_data);
+    }
+
+    body.extend_from_slice(&(ext_blob.len() as u16).to_be_bytes());
+    body.extend_from_slice(&ext_blob);
+
+    let mut handshake = Vec::new();
+    handshake.push(0x01);
+    let body_len = (body.len() as u32).to_be_bytes();
+    handshake.extend_from_slice(&body_len[1..4]);
+    handshake.extend_from_slice(&body);
+
+    let mut record = Vec::new();
+    record.push(TLS_RECORD_HANDSHAKE);
+    record.extend_from_slice(&[0x03, 0x01]);
+    record.extend_from_slice(&(handshake.len() as u16).to_be_bytes());
+    record.extend_from_slice(&handshake);
+    record
+}
+
+#[test]
+fn client_hello_fuzz_corpus_never_panics_or_accepts_corruption() {
+    let valid = make_valid_client_hello_record("example.com", &[b"h2", b"http/1.1"]);
+    assert_eq!(
+        extract_sni_from_client_hello(&valid).as_deref(),
+        Some("example.com")
+    );
+    assert_eq!(
+        extract_alpn_from_client_hello(&valid),
+        vec![b"h2".to_vec(), b"http/1.1".to_vec()]
+    );
+    assert!(
+        extract_sni_from_client_hello(&make_valid_client_hello_record("127.0.0.1", &[])).is_none(),
+        "literal IP hostnames must be rejected"
+    );
+
+    let mut corpus = vec![
+        Vec::new(),
+        vec![0x16, 0x03, 0x03],
+        valid[..9].to_vec(),
+        valid[..valid.len() - 1].to_vec(),
+    ];
+
+    let mut wrong_type = valid.clone();
+    wrong_type[0] = 0x15;
+    corpus.push(wrong_type);
+
+    let mut wrong_handshake = valid.clone();
+    wrong_handshake[5] = 0x02;
+    corpus.push(wrong_handshake);
+
+    let mut wrong_length = valid.clone();
+    wrong_length[3] ^= 0x7f;
+    corpus.push(wrong_length);
+
+    for (idx, input) in corpus.iter().enumerate() {
+        assert!(catch_unwind(|| extract_sni_from_client_hello(input)).is_ok());
+        assert!(catch_unwind(|| extract_alpn_from_client_hello(input)).is_ok());
+
+        if idx == 0 {
+            continue;
+        }
+
+        assert!(
+            extract_sni_from_client_hello(input).is_none(),
+            "corpus item {idx} must fail closed for SNI"
+        );
+        assert!(
+            extract_alpn_from_client_hello(input).is_empty(),
+            "corpus item {idx} must fail closed for ALPN"
+        );
+    }
+}
+
+#[test]
+fn tls_handshake_fuzz_corpus_never_panics_and_rejects_digest_mutations() {
+    let secret = b"tls_fuzz_security_secret";
+    let now: i64 = 1_700_000_000;
+    let base = make_valid_tls_handshake_with_session_id(secret, now as u32, &[0x42; 32]);
+    let secrets = vec![("fuzz-user".to_string(), secret.to_vec())];
+
+    assert!(validate_tls_handshake_at_time(&base, &secrets, false, now).is_some());
+
+    let mut corpus = Vec::new();
+
+    let mut truncated = base.clone();
+    truncated.truncate(TLS_DIGEST_POS + 16);
+    corpus.push(truncated);
+
+    let mut digest_flip = base.clone();
+    digest_flip[TLS_DIGEST_POS + 7] ^= 0x80;
+    corpus.push(digest_flip);
+
+    let mut session_id_len_overflow = base.clone();
+    session_id_len_overflow[TLS_DIGEST_POS + TLS_DIGEST_LEN] = 33;
+    corpus.push(session_id_len_overflow);
+
+    let mut timestamp_far_past = base.clone();
+    timestamp_far_past[TLS_DIGEST_POS + 28..TLS_DIGEST_POS + 32]
+        .copy_from_slice(&((now - i64::from(TIME_SKEW_MAX) - 1) as u32).to_le_bytes());
+    corpus.push(timestamp_far_past);
+
+    let mut timestamp_far_future = base.clone();
+    timestamp_far_future[TLS_DIGEST_POS + 28..TLS_DIGEST_POS + 32]
+        .copy_from_slice(&((now - TIME_SKEW_MIN + 1) as u32).to_le_bytes());
+    corpus.push(timestamp_far_future);
+
+    let mut seed = 0xA5A5_5A5A_F00D_BAAD_u64;
+    for _ in 0..32 {
+        let mut mutated = base.clone();
+        for _ in 0..2 {
+            seed = seed
+                .wrapping_mul(2862933555777941757)
+                .wrapping_add(3037000493);
+            let idx = TLS_DIGEST_POS + (seed as usize % TLS_DIGEST_LEN);
+            mutated[idx] ^= ((seed >> 17) as u8).wrapping_add(1);
+        }
+        corpus.push(mutated);
+    }
+
+    for (idx, handshake) in corpus.iter().enumerate() {
+        let result =
+            catch_unwind(|| validate_tls_handshake_at_time(handshake, &secrets, false, now));
+        assert!(result.is_ok(), "corpus item {idx} must not panic");
+        assert!(
+            result.unwrap().is_none(),
+            "corpus item {idx} must fail closed"
+        );
+    }
+}
+
+#[test]
+fn tls_boot_time_acceptance_is_capped_by_replay_window() {
+    let secret = b"tls_boot_time_cap_secret";
+    let secrets = vec![("boot-user".to_string(), secret.to_vec())];
+    let boot_ts = 1u32;
+    let handshake = make_valid_tls_handshake_with_session_id(secret, boot_ts, &[0x42; 32]);
+
+    assert!(
+        validate_tls_handshake_with_replay_window(&handshake, &secrets, false, 300).is_some(),
+        "boot-time timestamp should be accepted while replay window permits it"
+    );
+    assert!(
+        validate_tls_handshake_with_replay_window(&handshake, &secrets, false, 0).is_none(),
+        "boot-time timestamp must be rejected when replay window disables the bypass"
+    );
+}

src/protocol/tests/tls_length_cast_hardening_security_tests.rs

@@ -0,0 +1,37 @@
+use super::*;
+
+#[test]
+fn extension_builder_fails_closed_on_u16_length_overflow() {
+    let builder = TlsExtensionBuilder {
+        extensions: vec![0u8; (u16::MAX as usize) + 1],
+    };
+
+    let built = builder.build();
+    assert!(
+        built.is_empty(),
+        "oversized extension blob must fail closed instead of truncating length field"
+    );
+}
+
+#[test]
+fn server_hello_builder_fails_closed_on_session_id_len_overflow() {
+    let builder = ServerHelloBuilder {
+        random: [0u8; 32],
+        session_id: vec![0xAB; (u8::MAX as usize) + 1],
+        cipher_suite: cipher_suite::TLS_AES_128_GCM_SHA256,
+        compression: 0,
+        extensions: TlsExtensionBuilder::new(),
+    };
+
+    let message = builder.build_message();
+    let record = builder.build_record();
+
+    assert!(
+        message.is_empty(),
+        "session_id length overflow must fail closed in message builder"
+    );
+    assert!(
+        record.is_empty(),
+        "session_id length overflow must fail closed in record builder"
+    );
+}

src/protocol/tests/tls_size_constants_security_tests.rs

@@ -0,0 +1,11 @@
+use super::{MAX_TLS_CIPHERTEXT_SIZE, MAX_TLS_PLAINTEXT_SIZE, MIN_TLS_CLIENT_HELLO_SIZE};
+
+#[test]
+fn tls_size_constants_match_rfc_8446() {
+    assert_eq!(MAX_TLS_PLAINTEXT_SIZE, 16_384);
+    assert_eq!(MAX_TLS_CIPHERTEXT_SIZE, 16_640);
+
+    assert!(MIN_TLS_CLIENT_HELLO_SIZE < 512);
+    assert!(MIN_TLS_CLIENT_HELLO_SIZE > 64);
+    assert!(MAX_TLS_CIPHERTEXT_SIZE > MAX_TLS_PLAINTEXT_SIZE);
+}

src/proxy/adaptive_buffers.rs

@@ -1,3 +1,8 @@
+#![allow(dead_code)]
+
+// Adaptive buffer policy is staged and retained for deterministic rollout.
+// Keep definitions compiled for compatibility and security test scaffolding.
+
 use dashmap::DashMap;
 use std::cmp::max;
 use std::sync::OnceLock;
@@ -170,7 +175,8 @@ impl SessionAdaptiveController {
             return self.promote(TierTransitionReason::SoftConfirmed, 0);
         }
 
-        let demote_candidate = self.throughput_ema_bps < THROUGHPUT_DOWN_BPS && !tier2_now && !hard_now;
+        let demote_candidate =
+            self.throughput_ema_bps < THROUGHPUT_DOWN_BPS && !tier2_now && !hard_now;
         if demote_candidate {
             self.quiet_ticks = self.quiet_ticks.saturating_add(1);
             if self.quiet_ticks >= QUIET_DEMOTE_TICKS {
@@ -253,10 +259,7 @@ pub fn record_user_tier(user: &str, tier: AdaptiveTier) {
         };
         return;
     }
-    profiles().insert(
-        user.to_string(),
-        UserAdaptiveProfile { tier, seen_at: now },
-    );
+    profiles().insert(user.to_string(), UserAdaptiveProfile { tier, seen_at: now });
 }
 
 pub fn direct_copy_buffers_for_tier(
@@ -339,10 +342,7 @@ mod tests {
                 sample(
                     300_000, // ~9.6 Mbps
                     320_000, // incoming > outgoing to confirm tier2
-                    250_000,
-                    10,
-                    0,
-                    0,
+                    250_000, 10, 0, 0,
                 ),
                 tick_secs,
             );
@@ -358,10 +358,7 @@ mod tests {
     fn test_hard_promotion_on_pending_pressure() {
         let mut ctrl = SessionAdaptiveController::new(AdaptiveTier::Base);
         let transition = ctrl
-            .observe(
-                sample(10_000, 20_000, 10_000, 4, 1, 3),
-                0.25,
-            )
+            .observe(sample(10_000, 20_000, 10_000, 4, 1, 3), 0.25)
             .expect("expected hard promotion");
         assert_eq!(transition.reason, TierTransitionReason::HardPressure);
         assert_eq!(transition.to, AdaptiveTier::Tier1);

src/proxy/direct_relay.rs

@@ -1,7 +1,11 @@
+use std::collections::HashSet;
+use std::ffi::OsString;
 use std::fs::OpenOptions;
 use std::io::Write;
 use std::net::SocketAddr;
+use std::path::{Component, Path, PathBuf};
 use std::sync::Arc;
+use std::sync::{Mutex, OnceLock};
 
 use tokio::io::{AsyncRead, AsyncWrite, AsyncWriteExt, ReadHalf, WriteHalf, split};
 use tokio::sync::watch;
@@ -17,11 +21,209 @@ use crate::proxy::route_mode::{
     ROUTE_SWITCH_ERROR_MSG, RelayRouteMode, RouteCutoverState, affected_cutover_state,
     cutover_stagger_delay,
 };
-use crate::proxy::adaptive_buffers;
-use crate::proxy::session_eviction::SessionLease;
 use crate::stats::Stats;
 use crate::stream::{BufferPool, CryptoReader, CryptoWriter};
 use crate::transport::UpstreamManager;
+#[cfg(unix)]
+use nix::fcntl::{Flock, FlockArg, OFlag, openat};
+#[cfg(unix)]
+use nix::sys::stat::Mode;
+
+#[cfg(unix)]
+use std::os::unix::fs::OpenOptionsExt;
+
+const UNKNOWN_DC_LOG_DISTINCT_LIMIT: usize = 1024;
+static LOGGED_UNKNOWN_DCS: OnceLock<Mutex<HashSet<i16>>> = OnceLock::new();
+const MAX_SCOPE_HINT_LEN: usize = 64;
+
+fn validated_scope_hint(user: &str) -> Option<&str> {
+    let scope = user.strip_prefix("scope_")?;
+    if scope.is_empty() || scope.len() > MAX_SCOPE_HINT_LEN {
+        return None;
+    }
+    if scope
+        .bytes()
+        .all(|b| b.is_ascii_alphanumeric() || b == b'-')
+    {
+        Some(scope)
+    } else {
+        None
+    }
+}
+
+#[derive(Clone)]
+struct SanitizedUnknownDcLogPath {
+    resolved_path: PathBuf,
+    allowed_parent: PathBuf,
+    file_name: OsString,
+}
+
+// In tests, this function shares global mutable state. Callers that also use
+// cache-reset helpers must hold `unknown_dc_test_lock()` to keep assertions
+// deterministic under parallel execution.
+fn should_log_unknown_dc(dc_idx: i16) -> bool {
+    let set = LOGGED_UNKNOWN_DCS.get_or_init(|| Mutex::new(HashSet::new()));
+    should_log_unknown_dc_with_set(set, dc_idx)
+}
+
+fn should_log_unknown_dc_with_set(set: &Mutex<HashSet<i16>>, dc_idx: i16) -> bool {
+    match set.lock() {
+        Ok(mut guard) => {
+            if guard.contains(&dc_idx) {
+                return false;
+            }
+            if guard.len() >= UNKNOWN_DC_LOG_DISTINCT_LIMIT {
+                return false;
+            }
+            guard.insert(dc_idx)
+        }
+        // Fail closed on poisoned state to avoid unbounded blocking log writes.
+        Err(_) => false,
+    }
+}
+
+fn sanitize_unknown_dc_log_path(path: &str) -> Option<SanitizedUnknownDcLogPath> {
+    let candidate = Path::new(path);
+    if candidate.as_os_str().is_empty() {
+        return None;
+    }
+    if candidate
+        .components()
+        .any(|component| matches!(component, Component::ParentDir))
+    {
+        return None;
+    }
+
+    let cwd = std::env::current_dir().ok()?;
+    let file_name = candidate.file_name()?;
+    let parent = candidate.parent().unwrap_or_else(|| Path::new("."));
+    let parent_path = if parent.is_absolute() {
+        parent.to_path_buf()
+    } else {
+        cwd.join(parent)
+    };
+    let canonical_parent = parent_path.canonicalize().ok()?;
+    if !canonical_parent.is_dir() {
+        return None;
+    }
+
+    Some(SanitizedUnknownDcLogPath {
+        resolved_path: canonical_parent.join(file_name),
+        allowed_parent: canonical_parent,
+        file_name: file_name.to_os_string(),
+    })
+}
+
+fn unknown_dc_log_path_is_still_safe(path: &SanitizedUnknownDcLogPath) -> bool {
+    let Some(parent) = path.resolved_path.parent() else {
+        return false;
+    };
+    let Ok(current_parent) = parent.canonicalize() else {
+        return false;
+    };
+    if current_parent != path.allowed_parent {
+        return false;
+    }
+
+    if let Ok(canonical_target) = path.resolved_path.canonicalize() {
+        let Some(target_parent) = canonical_target.parent() else {
+            return false;
+        };
+        let Some(target_name) = canonical_target.file_name() else {
+            return false;
+        };
+        if target_parent != path.allowed_parent || target_name != path.file_name {
+            return false;
+        }
+    }
+
+    true
+}
+
+#[cfg(test)]
+fn open_unknown_dc_log_append(path: &Path) -> std::io::Result<std::fs::File> {
+    #[cfg(unix)]
+    {
+        OpenOptions::new()
+            .create(true)
+            .append(true)
+            .custom_flags(libc::O_NOFOLLOW)
+            .open(path)
+    }
+    #[cfg(not(unix))]
+    {
+        let _ = path;
+        Err(std::io::Error::new(
+            std::io::ErrorKind::PermissionDenied,
+            "unknown_dc_file_log_enabled requires unix O_NOFOLLOW support",
+        ))
+    }
+}
+
+fn open_unknown_dc_log_append_anchored(
+    path: &SanitizedUnknownDcLogPath,
+) -> std::io::Result<std::fs::File> {
+    #[cfg(unix)]
+    {
+        let parent = OpenOptions::new()
+            .read(true)
+            .custom_flags(libc::O_DIRECTORY | libc::O_NOFOLLOW | libc::O_CLOEXEC)
+            .open(&path.allowed_parent)?;
+
+        let oflags = OFlag::O_CREAT
+            | OFlag::O_APPEND
+            | OFlag::O_WRONLY
+            | OFlag::O_NOFOLLOW
+            | OFlag::O_CLOEXEC;
+        let mode = Mode::from_bits_truncate(0o600);
+        let path_component = Path::new(path.file_name.as_os_str());
+        let fd = openat(&parent, path_component, oflags, mode)
+            .map_err(|err| std::io::Error::from_raw_os_error(err as i32))?;
+        let file = std::fs::File::from(fd);
+        Ok(file)
+    }
+    #[cfg(not(unix))]
+    {
+        let _ = path;
+        Err(std::io::Error::new(
+            std::io::ErrorKind::PermissionDenied,
+            "unknown_dc_file_log_enabled requires unix O_NOFOLLOW support",
+        ))
+    }
+}
+
+fn append_unknown_dc_line(file: &mut std::fs::File, dc_idx: i16) -> std::io::Result<()> {
+    #[cfg(unix)]
+    {
+        let cloned = file.try_clone()?;
+        let mut locked = Flock::lock(cloned, FlockArg::LockExclusive)
+            .map_err(|(_, err)| std::io::Error::from_raw_os_error(err as i32))?;
+        let write_result = writeln!(&mut *locked, "dc_idx={dc_idx}");
+        let _ = locked
+            .unlock()
+            .map_err(|(_, err)| std::io::Error::from_raw_os_error(err as i32))?;
+        write_result
+    }
+    #[cfg(not(unix))]
+    {
+        writeln!(file, "dc_idx={dc_idx}")
+    }
+}
+
+#[cfg(test)]
+fn clear_unknown_dc_log_cache_for_testing() {
+    if let Some(set) = LOGGED_UNKNOWN_DCS.get()
+        && let Ok(mut guard) = set.lock()
+    {
+        guard.clear();
+    }
+}
+
+#[cfg(test)]
+fn unknown_dc_test_lock() -> &'static Mutex<()> {
+    static TEST_LOCK: OnceLock<Mutex<()>> = OnceLock::new();
+    TEST_LOCK.get_or_init(|| Mutex::new(()))
+}
 
 pub(crate) async fn handle_via_direct<R, W>(
     client_reader: CryptoReader<R>,
@@ -35,7 +237,6 @@ pub(crate) async fn handle_via_direct<R, W>(
     mut route_rx: watch::Receiver<RouteCutoverState>,
     route_snapshot: RouteCutoverState,
     session_id: u64,
-    session_lease: SessionLease,
 ) -> Result<()>
 where
     R: AsyncRead + Unpin + Send + 'static,
@@ -54,12 +255,15 @@ where
         "Connecting to Telegram DC"
     );
 
+    let scope_hint = validated_scope_hint(user);
+    if user.starts_with("scope_") && scope_hint.is_none() {
+        warn!(
+            user = %user,
+            "Ignoring invalid scope hint and falling back to default upstream selection"
+        );
+    }
     let tg_stream = upstream_manager
-        .connect(
-            dc_addr,
-            Some(success.dc_idx),
-            user.strip_prefix("scope_").filter(|s| !s.is_empty()),
-        )
+        .connect(dc_addr, Some(success.dc_idx), scope_hint)
         .await?;
 
     debug!(peer = %success.peer, dc_addr = %dc_addr, "Connected, performing TG handshake");
@@ -70,29 +274,19 @@ where
     debug!(peer = %success.peer, "TG handshake complete, starting relay");
 
     stats.increment_user_connects(user);
-    stats.increment_user_curr_connects(user);
-    stats.increment_current_connections_direct();
-
-    let seed_tier = adaptive_buffers::seed_tier_for_user(user);
-    let (c2s_copy_buf, s2c_copy_buf) = adaptive_buffers::direct_copy_buffers_for_tier(
-        seed_tier,
-        config.general.direct_relay_copy_buf_c2s_bytes,
-        config.general.direct_relay_copy_buf_s2c_bytes,
-    );
+    let _direct_connection_lease = stats.acquire_direct_connection_lease();
 
     let relay_result = relay_bidirectional(
         client_reader,
         client_writer,
         tg_reader,
         tg_writer,
-        c2s_copy_buf,
-        s2c_copy_buf,
+        config.general.direct_relay_copy_buf_c2s_bytes,
+        config.general.direct_relay_copy_buf_s2c_bytes,
         user,
-        success.dc_idx,
         Arc::clone(&stats),
+        config.access.user_data_quota.get(user).copied(),
         buffer_pool,
-        session_lease,
-        seed_tier,
     );
     tokio::pin!(relay_result);
     let relay_result = loop {
@@ -122,9 +316,6 @@ where
         }
     };
 
-    stats.decrement_current_connections_direct();
-    stats.decrement_user_curr_connects(user);
-
     match &relay_result {
         Ok(()) => debug!(user = %user, "Direct relay completed"),
         Err(e) => debug!(user = %user, error = %e, "Direct relay ended with error"),
@@ -181,20 +372,27 @@ fn get_dc_addr_static(dc_idx: i16, config: &ProxyConfig) -> Result<SocketAddr> {
             && let Some(path) = &config.general.unknown_dc_log_path
             && let Ok(handle) = tokio::runtime::Handle::try_current()
         {
-            let path = path.clone();
+            if let Some(path) = sanitize_unknown_dc_log_path(path) {
+                if should_log_unknown_dc(dc_idx) {
                     handle.spawn_blocking(move || {
-                if let Ok(mut file) = OpenOptions::new().create(true).append(true).open(path) {
-                    let _ = writeln!(file, "dc_idx={dc_idx}");
+                        if unknown_dc_log_path_is_still_safe(&path)
+                            && let Ok(mut file) = open_unknown_dc_log_append_anchored(&path)
+                        {
+                            let _ = append_unknown_dc_line(&mut file, dc_idx);
                         }
                     });
                 }
+            } else {
+                warn!(dc_idx = dc_idx, raw_path = %path, "Rejected unsafe unknown DC log path");
+            }
+        }
     }
 
     let default_dc = config.default_dc.unwrap_or(2) as usize;
     let fallback_idx = if default_dc >= 1 && default_dc <= num_dcs {
         default_dc - 1
     } else {
-        1
+        0
     };
 
     info!(
@@ -222,8 +420,6 @@ where
     let (nonce, _tg_enc_key, _tg_enc_iv, _tg_dec_key, _tg_dec_iv) = generate_tg_nonce(
         success.proto_tag,
         success.dc_idx,
-        &success.dec_key,
-        success.dec_iv,
         &success.enc_key,
         success.enc_iv,
         rng,
@@ -249,3 +445,19 @@ where
         CryptoWriter::new(write_half, tg_encryptor, max_pending),
     ))
 }
+
+#[cfg(test)]
+#[path = "tests/direct_relay_security_tests.rs"]
+mod security_tests;
+
+#[cfg(test)]
+#[path = "tests/direct_relay_business_logic_tests.rs"]
+mod business_logic_tests;
+
+#[cfg(test)]
+#[path = "tests/direct_relay_common_mistakes_tests.rs"]
+mod common_mistakes_tests;
+
+#[cfg(test)]
+#[path = "tests/direct_relay_subtle_adversarial_tests.rs"]
+mod subtle_adversarial_tests;

src/proxy/mod.rs

@@ -1,13 +1,71 @@
 //! Proxy Defs
 
+// Apply strict linting to proxy production code while keeping test builds noise-tolerant.
+#![cfg_attr(test, allow(warnings))]
+#![cfg_attr(not(test), forbid(clippy::undocumented_unsafe_blocks))]
+#![cfg_attr(
+    not(test),
+    deny(
+        clippy::unwrap_used,
+        clippy::expect_used,
+        clippy::panic,
+        clippy::todo,
+        clippy::unimplemented,
+        clippy::correctness,
+        clippy::option_if_let_else,
+        clippy::or_fun_call,
+        clippy::branches_sharing_code,
+        clippy::single_option_map,
+        clippy::useless_let_if_seq,
+        clippy::redundant_locals,
+        clippy::cloned_ref_to_slice_refs,
+        unsafe_code,
+        clippy::await_holding_lock,
+        clippy::await_holding_refcell_ref,
+        clippy::debug_assert_with_mut_call,
+        clippy::macro_use_imports,
+        clippy::cast_ptr_alignment,
+        clippy::cast_lossless,
+        clippy::ptr_as_ptr,
+        clippy::large_stack_arrays,
+        clippy::same_functions_in_if_condition,
+        trivial_casts,
+        trivial_numeric_casts,
+        unused_extern_crates,
+        unused_import_braces,
+        rust_2018_idioms
+    )
+)]
+#![cfg_attr(
+    not(test),
+    allow(
+        clippy::use_self,
+        clippy::redundant_closure,
+        clippy::too_many_arguments,
+        clippy::doc_markdown,
+        clippy::missing_const_for_fn,
+        clippy::unnecessary_operation,
+        clippy::redundant_pub_crate,
+        clippy::derive_partial_eq_without_eq,
+        clippy::type_complexity,
+        clippy::new_ret_no_self,
+        clippy::cast_possible_truncation,
+        clippy::cast_possible_wrap,
+        clippy::significant_drop_tightening,
+        clippy::significant_drop_in_scrutinee,
+        clippy::float_cmp,
+        clippy::nursery
+    )
+)]
+
 pub mod adaptive_buffers;
 pub mod client;
 pub mod direct_relay;
 pub mod handshake;
 pub mod masking;
 pub mod middle_relay;
-pub mod route_mode;
 pub mod relay;
+pub mod route_mode;
 pub mod session_eviction;
 
 pub use client::ClientHandler;

src/proxy/relay.rs

@@ -51,24 +51,18 @@
 //! - `poll_write` on client = S→C (to client)     → `octets_to`, `msgs_to`
 //! - `SharedCounters` (atomics) let the watchdog read stats without locking
 
+use crate::error::{ProxyError, Result};
+use crate::stats::{Stats, UserStats};
+use crate::stream::BufferPool;
 use std::io;
 use std::pin::Pin;
 use std::sync::Arc;
-use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
 use std::task::{Context, Poll};
 use std::time::Duration;
-use tokio::io::{
-    AsyncRead, AsyncWrite, AsyncWriteExt, ReadBuf, copy_bidirectional_with_sizes,
-};
+use tokio::io::{AsyncRead, AsyncWrite, AsyncWriteExt, ReadBuf, copy_bidirectional_with_sizes};
 use tokio::time::Instant;
 use tracing::{debug, trace, warn};
-use crate::error::Result;
-use crate::proxy::adaptive_buffers::{
-    self, AdaptiveTier, RelaySignalSample, SessionAdaptiveController, TierTransitionReason,
-};
-use crate::proxy::session_eviction::SessionLease;
-use crate::stats::Stats;
-use crate::stream::BufferPool;
 
 // ============= Constants =============
 
@@ -83,7 +77,11 @@ const ACTIVITY_TIMEOUT: Duration = Duration::from_secs(1800);
 /// 10 seconds gives responsive timeout detection (±10s accuracy)
 /// without measurable overhead from atomic reads.
 const WATCHDOG_INTERVAL: Duration = Duration::from_secs(10);
-const ADAPTIVE_TICK: Duration = Duration::from_millis(250);
+
+#[inline]
+fn watchdog_delta(current: u64, previous: u64) -> u64 {
+    current.saturating_sub(previous)
+}
 
 // ============= CombinedStream =============
 
@@ -160,16 +158,6 @@ struct SharedCounters {
     s2c_ops: AtomicU64,
     /// Milliseconds since relay epoch of last I/O activity
     last_activity_ms: AtomicU64,
-    /// Bytes requested to write to client (S→C direction).
-    s2c_requested_bytes: AtomicU64,
-    /// Total write operations for S→C direction.
-    s2c_write_ops: AtomicU64,
-    /// Number of partial writes to client.
-    s2c_partial_writes: AtomicU64,
-    /// Number of times S→C poll_write returned Pending.
-    s2c_pending_writes: AtomicU64,
-    /// Consecutive pending writes in S→C direction.
-    s2c_consecutive_pending_writes: AtomicU64,
 }
 
 impl SharedCounters {
@@ -180,11 +168,6 @@ impl SharedCounters {
             c2s_ops: AtomicU64::new(0),
             s2c_ops: AtomicU64::new(0),
             last_activity_ms: AtomicU64::new(0),
-            s2c_requested_bytes: AtomicU64::new(0),
-            s2c_write_ops: AtomicU64::new(0),
-            s2c_partial_writes: AtomicU64::new(0),
-            s2c_pending_writes: AtomicU64::new(0),
-            s2c_consecutive_pending_writes: AtomicU64::new(0),
         }
     }
 
@@ -225,6 +208,10 @@ struct StatsIo<S> {
     counters: Arc<SharedCounters>,
     stats: Arc<Stats>,
     user: String,
+    user_stats: Arc<UserStats>,
+    quota_limit: Option<u64>,
+    quota_exceeded: Arc<AtomicBool>,
+    quota_bytes_since_check: u64,
     epoch: Instant,
 }
 
@@ -234,12 +221,66 @@ impl<S> StatsIo<S> {
         counters: Arc<SharedCounters>,
         stats: Arc<Stats>,
         user: String,
+        quota_limit: Option<u64>,
+        quota_exceeded: Arc<AtomicBool>,
         epoch: Instant,
     ) -> Self {
         // Mark initial activity so the watchdog doesn't fire before data flows
         counters.touch(Instant::now(), epoch);
-        Self { inner, counters, stats, user, epoch }
+        let user_stats = stats.get_or_create_user_stats_handle(&user);
+        Self {
+            inner,
+            counters,
+            stats,
+            user,
+            user_stats,
+            quota_limit,
+            quota_exceeded,
+            quota_bytes_since_check: 0,
+            epoch,
         }
+    }
+}
+
+#[derive(Debug)]
+struct QuotaIoSentinel;
+
+impl std::fmt::Display for QuotaIoSentinel {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("user data quota exceeded")
+    }
+}
+
+impl std::error::Error for QuotaIoSentinel {}
+
+fn quota_io_error() -> io::Error {
+    io::Error::new(io::ErrorKind::PermissionDenied, QuotaIoSentinel)
+}
+
+fn is_quota_io_error(err: &io::Error) -> bool {
+    err.kind() == io::ErrorKind::PermissionDenied
+        && err
+            .get_ref()
+            .and_then(|source| source.downcast_ref::<QuotaIoSentinel>())
+            .is_some()
+}
+
+const QUOTA_NEAR_LIMIT_BYTES: u64 = 64 * 1024;
+const QUOTA_LARGE_CHARGE_BYTES: u64 = 16 * 1024;
+const QUOTA_ADAPTIVE_INTERVAL_MIN_BYTES: u64 = 4 * 1024;
+const QUOTA_ADAPTIVE_INTERVAL_MAX_BYTES: u64 = 64 * 1024;
+
+#[inline]
+fn quota_adaptive_interval_bytes(remaining_before: u64) -> u64 {
+    remaining_before.saturating_div(2).clamp(
+        QUOTA_ADAPTIVE_INTERVAL_MIN_BYTES,
+        QUOTA_ADAPTIVE_INTERVAL_MAX_BYTES,
+    )
+}
+
+#[inline]
+fn should_immediate_quota_check(remaining_before: u64, charge_bytes: u64) -> bool {
+    remaining_before <= QUOTA_NEAR_LIMIT_BYTES || charge_bytes >= QUOTA_LARGE_CHARGE_BYTES
 }
 
 impl<S: AsyncRead + Unpin> AsyncRead for StatsIo<S> {
@@ -249,19 +290,61 @@ impl<S: AsyncRead + Unpin> AsyncRead for StatsIo<S> {
         buf: &mut ReadBuf<'_>,
     ) -> Poll<io::Result<()>> {
         let this = self.get_mut();
+        if this.quota_exceeded.load(Ordering::Acquire) {
+            return Poll::Ready(Err(quota_io_error()));
+        }
+
+        let mut remaining_before = None;
+        if let Some(limit) = this.quota_limit {
+            let used_before = this.user_stats.quota_used();
+            let remaining = limit.saturating_sub(used_before);
+            if remaining == 0 {
+                this.quota_exceeded.store(true, Ordering::Release);
+                return Poll::Ready(Err(quota_io_error()));
+            }
+            remaining_before = Some(remaining);
+        }
+
         let before = buf.filled().len();
 
         match Pin::new(&mut this.inner).poll_read(cx, buf) {
             Poll::Ready(Ok(())) => {
                 let n = buf.filled().len() - before;
                 if n > 0 {
+                    let n_to_charge = n as u64;
+
                     // C→S: client sent data
-                    this.counters.c2s_bytes.fetch_add(n as u64, Ordering::Relaxed);
+                    this.counters
+                        .c2s_bytes
+                        .fetch_add(n_to_charge, Ordering::Relaxed);
                     this.counters.c2s_ops.fetch_add(1, Ordering::Relaxed);
                     this.counters.touch(Instant::now(), this.epoch);
 
-                    this.stats.add_user_octets_from(&this.user, n as u64);
-                    this.stats.increment_user_msgs_from(&this.user);
+                    this.stats
+                        .add_user_octets_from_handle(this.user_stats.as_ref(), n_to_charge);
+                    this.stats
+                        .increment_user_msgs_from_handle(this.user_stats.as_ref());
+
+                    if let (Some(limit), Some(remaining)) = (this.quota_limit, remaining_before) {
+                        this.stats
+                            .quota_charge_post_write(this.user_stats.as_ref(), n_to_charge);
+                        if should_immediate_quota_check(remaining, n_to_charge) {
+                            this.quota_bytes_since_check = 0;
+                            if this.user_stats.quota_used() >= limit {
+                                this.quota_exceeded.store(true, Ordering::Release);
+                            }
+                        } else {
+                            this.quota_bytes_since_check =
+                                this.quota_bytes_since_check.saturating_add(n_to_charge);
+                            let interval = quota_adaptive_interval_bytes(remaining);
+                            if this.quota_bytes_since_check >= interval {
+                                this.quota_bytes_since_check = 0;
+                                if this.user_stats.quota_used() >= limit {
+                                    this.quota_exceeded.store(true, Ordering::Release);
+                                }
+                            }
+                        }
+                    }
 
                     trace!(user = %this.user, bytes = n, "C->S");
                 }
@@ -279,43 +362,63 @@ impl<S: AsyncWrite + Unpin> AsyncWrite for StatsIo<S> {
         buf: &[u8],
     ) -> Poll<io::Result<usize>> {
         let this = self.get_mut();
-        this.counters
-            .s2c_requested_bytes
-            .fetch_add(buf.len() as u64, Ordering::Relaxed);
+        if this.quota_exceeded.load(Ordering::Acquire) {
+            return Poll::Ready(Err(quota_io_error()));
+        }
+
+        let mut remaining_before = None;
+        if let Some(limit) = this.quota_limit {
+            let used_before = this.user_stats.quota_used();
+            let remaining = limit.saturating_sub(used_before);
+            if remaining == 0 {
+                this.quota_exceeded.store(true, Ordering::Release);
+                return Poll::Ready(Err(quota_io_error()));
+            }
+            remaining_before = Some(remaining);
+        }
 
         match Pin::new(&mut this.inner).poll_write(cx, buf) {
             Poll::Ready(Ok(n)) => {
-                this.counters.s2c_write_ops.fetch_add(1, Ordering::Relaxed);
-                this.counters
-                    .s2c_consecutive_pending_writes
-                    .store(0, Ordering::Relaxed);
-                if n < buf.len() {
-                    this.counters
-                        .s2c_partial_writes
-                        .fetch_add(1, Ordering::Relaxed);
-                }
                 if n > 0 {
+                    let n_to_charge = n as u64;
+
                     // S→C: data written to client
-                    this.counters.s2c_bytes.fetch_add(n as u64, Ordering::Relaxed);
+                    this.counters
+                        .s2c_bytes
+                        .fetch_add(n_to_charge, Ordering::Relaxed);
                     this.counters.s2c_ops.fetch_add(1, Ordering::Relaxed);
                     this.counters.touch(Instant::now(), this.epoch);
 
-                    this.stats.add_user_octets_to(&this.user, n as u64);
-                    this.stats.increment_user_msgs_to(&this.user);
+                    this.stats
+                        .add_user_octets_to_handle(this.user_stats.as_ref(), n_to_charge);
+                    this.stats
+                        .increment_user_msgs_to_handle(this.user_stats.as_ref());
+
+                    if let (Some(limit), Some(remaining)) = (this.quota_limit, remaining_before) {
+                        this.stats
+                            .quota_charge_post_write(this.user_stats.as_ref(), n_to_charge);
+                        if should_immediate_quota_check(remaining, n_to_charge) {
+                            this.quota_bytes_since_check = 0;
+                            if this.user_stats.quota_used() >= limit {
+                                this.quota_exceeded.store(true, Ordering::Release);
+                            }
+                        } else {
+                            this.quota_bytes_since_check =
+                                this.quota_bytes_since_check.saturating_add(n_to_charge);
+                            let interval = quota_adaptive_interval_bytes(remaining);
+                            if this.quota_bytes_since_check >= interval {
+                                this.quota_bytes_since_check = 0;
+                                if this.user_stats.quota_used() >= limit {
+                                    this.quota_exceeded.store(true, Ordering::Release);
+                                }
+                            }
+                        }
+                    }
 
                     trace!(user = %this.user, bytes = n, "S->C");
                 }
                 Poll::Ready(Ok(n))
             }
-            Poll::Pending => {
-                this.counters
-                    .s2c_pending_writes
-                    .fetch_add(1, Ordering::Relaxed);
-                this.counters
-                    .s2c_consecutive_pending_writes
-                    .fetch_add(1, Ordering::Relaxed);
-                Poll::Pending
-            }
             other => other,
         }
     }
@@ -348,7 +451,8 @@ impl<S: AsyncWrite + Unpin> AsyncWrite for StatsIo<S> {
 /// - Per-user stats: bytes and ops counted per direction
 /// - Periodic rate logging: every 10 seconds when active
 /// - Clean shutdown: both write sides are shut down on exit
-/// - Error propagation: I/O errors are returned as `ProxyError::Io`
+/// - Error propagation: quota exits return `ProxyError::DataQuotaExceeded`,
+///   other I/O failures are returned as `ProxyError::Io`
 pub async fn relay_bidirectional<CR, CW, SR, SW>(
     client_reader: CR,
     client_writer: CW,
@@ -357,11 +461,9 @@ pub async fn relay_bidirectional<CR, CW, SR, SW>(
     c2s_buf_size: usize,
     s2c_buf_size: usize,
     user: &str,
-    dc_idx: i16,
     stats: Arc<Stats>,
+    quota_limit: Option<u64>,
     _buffer_pool: Arc<BufferPool>,
-    session_lease: SessionLease,
-    seed_tier: AdaptiveTier,
 ) -> Result<()>
 where
     CR: AsyncRead + Unpin + Send + 'static,
@@ -371,6 +473,7 @@ where
 {
     let epoch = Instant::now();
     let counters = Arc::new(SharedCounters::new());
+    let quota_exceeded = Arc::new(AtomicBool::new(false));
     let user_owned = user.to_string();
 
     // ── Combine split halves into bidirectional streams ──────────────
@@ -383,43 +486,31 @@ where
         Arc::clone(&counters),
         Arc::clone(&stats),
         user_owned.clone(),
+        quota_limit,
+        Arc::clone(&quota_exceeded),
         epoch,
     );
 
     // ── Watchdog: activity timeout + periodic rate logging ──────────
     let wd_counters = Arc::clone(&counters);
     let wd_user = user_owned.clone();
-    let wd_dc = dc_idx;
-    let wd_stats = Arc::clone(&stats);
-    let wd_session = session_lease.clone();
+    let wd_quota_exceeded = Arc::clone(&quota_exceeded);
 
     let watchdog = async {
-        let mut prev_c2s_log: u64 = 0;
-        let mut prev_s2c_log: u64 = 0;
-        let mut prev_c2s_sample: u64 = 0;
-        let mut prev_s2c_requested_sample: u64 = 0;
-        let mut prev_s2c_written_sample: u64 = 0;
-        let mut prev_s2c_write_ops_sample: u64 = 0;
-        let mut prev_s2c_partial_sample: u64 = 0;
-        let mut accumulated_log = Duration::ZERO;
-        let mut adaptive = SessionAdaptiveController::new(seed_tier);
+        let mut prev_c2s: u64 = 0;
+        let mut prev_s2c: u64 = 0;
 
         loop {
-            tokio::time::sleep(ADAPTIVE_TICK).await;
-
-            if wd_session.is_stale() {
-                wd_stats.increment_reconnect_stale_close_total();
-                warn!(
-                    user = %wd_user,
-                    dc = wd_dc,
-                    "Session evicted by reconnect"
-                );
-                return;
-            }
+            tokio::time::sleep(WATCHDOG_INTERVAL).await;
 
             let now = Instant::now();
             let idle = wd_counters.idle_duration(now, epoch);
 
+            if wd_quota_exceeded.load(Ordering::Acquire) {
+                warn!(user = %wd_user, "User data quota reached, closing relay");
+                return;
+            }
+
             // ── Activity timeout ────────────────────────────────────
             if idle >= ACTIVITY_TIMEOUT {
                 let c2s = wd_counters.c2s_bytes.load(Ordering::Relaxed);
@@ -434,80 +525,11 @@ where
                 return; // Causes select! to cancel copy_bidirectional
             }
 
-            let c2s_total = wd_counters.c2s_bytes.load(Ordering::Relaxed);
-            let s2c_requested_total = wd_counters
-                .s2c_requested_bytes
-                .load(Ordering::Relaxed);
-            let s2c_written_total = wd_counters.s2c_bytes.load(Ordering::Relaxed);
-            let s2c_write_ops_total = wd_counters
-                .s2c_write_ops
-                .load(Ordering::Relaxed);
-            let s2c_partial_total = wd_counters
-                .s2c_partial_writes
-                .load(Ordering::Relaxed);
-            let consecutive_pending = wd_counters
-                .s2c_consecutive_pending_writes
-                .load(Ordering::Relaxed) as u32;
-
-            let sample = RelaySignalSample {
-                c2s_bytes: c2s_total.saturating_sub(prev_c2s_sample),
-                s2c_requested_bytes: s2c_requested_total
-                    .saturating_sub(prev_s2c_requested_sample),
-                s2c_written_bytes: s2c_written_total
-                    .saturating_sub(prev_s2c_written_sample),
-                s2c_write_ops: s2c_write_ops_total
-                    .saturating_sub(prev_s2c_write_ops_sample),
-                s2c_partial_writes: s2c_partial_total
-                    .saturating_sub(prev_s2c_partial_sample),
-                s2c_consecutive_pending_writes: consecutive_pending,
-            };
-
-            if let Some(transition) = adaptive.observe(sample, ADAPTIVE_TICK.as_secs_f64()) {
-                match transition.reason {
-                    TierTransitionReason::SoftConfirmed => {
-                        wd_stats.increment_relay_adaptive_promotions_total();
-                    }
-                    TierTransitionReason::HardPressure => {
-                        wd_stats.increment_relay_adaptive_promotions_total();
-                        wd_stats.increment_relay_adaptive_hard_promotions_total();
-                    }
-                    TierTransitionReason::QuietDemotion => {
-                        wd_stats.increment_relay_adaptive_demotions_total();
-                    }
-                }
-                adaptive_buffers::record_user_tier(&wd_user, adaptive.max_tier_seen());
-                debug!(
-                    user = %wd_user,
-                    dc = wd_dc,
-                    from_tier = transition.from.as_u8(),
-                    to_tier = transition.to.as_u8(),
-                    reason = ?transition.reason,
-                    throughput_ema_bps = sample
-                        .c2s_bytes
-                        .max(sample.s2c_written_bytes)
-                        .saturating_mul(8)
-                        .saturating_mul(4),
-                    "Adaptive relay tier transition"
-                );
-            }
-
-            prev_c2s_sample = c2s_total;
-            prev_s2c_requested_sample = s2c_requested_total;
-            prev_s2c_written_sample = s2c_written_total;
-            prev_s2c_write_ops_sample = s2c_write_ops_total;
-            prev_s2c_partial_sample = s2c_partial_total;
-
-            accumulated_log = accumulated_log.saturating_add(ADAPTIVE_TICK);
-            if accumulated_log < WATCHDOG_INTERVAL {
-                continue;
-            }
-            accumulated_log = Duration::ZERO;
-
             // ── Periodic rate logging ───────────────────────────────
             let c2s = wd_counters.c2s_bytes.load(Ordering::Relaxed);
             let s2c = wd_counters.s2c_bytes.load(Ordering::Relaxed);
-            let c2s_delta = c2s.saturating_sub(prev_c2s_log);
-            let s2c_delta = s2c.saturating_sub(prev_s2c_log);
+            let c2s_delta = watchdog_delta(c2s, prev_c2s);
+            let s2c_delta = watchdog_delta(s2c, prev_s2c);
 
             if c2s_delta > 0 || s2c_delta > 0 {
                 let secs = WATCHDOG_INTERVAL.as_secs_f64();
@@ -521,8 +543,8 @@ where
                 );
             }
 
-            prev_c2s_log = c2s;
-            prev_s2c_log = s2c;
+            prev_c2s = c2s;
+            prev_s2c = s2c;
         }
     };
 
@@ -557,7 +579,6 @@ where
     let c2s_ops = counters.c2s_ops.load(Ordering::Relaxed);
     let s2c_ops = counters.s2c_ops.load(Ordering::Relaxed);
     let duration = epoch.elapsed();
-    adaptive_buffers::record_user_tier(&user_owned, seed_tier);
 
     match copy_result {
         Some(Ok((c2s, s2c))) => {
@@ -573,6 +594,22 @@ where
             );
             Ok(())
         }
+        Some(Err(e)) if is_quota_io_error(&e) => {
+            let c2s = counters.c2s_bytes.load(Ordering::Relaxed);
+            let s2c = counters.s2c_bytes.load(Ordering::Relaxed);
+            warn!(
+                user = %user_owned,
+                c2s_bytes = c2s,
+                s2c_bytes = s2c,
+                c2s_msgs = c2s_ops,
+                s2c_msgs = s2c_ops,
+                duration_secs = duration.as_secs(),
+                "Data quota reached, closing relay"
+            );
+            Err(ProxyError::DataQuotaExceeded {
+                user: user_owned.clone(),
+            })
+        }
         Some(Err(e)) => {
             // I/O error in one of the directions
             let c2s = counters.c2s_bytes.load(Ordering::Relaxed);
@@ -606,3 +643,31 @@ where
         }
     }
 }
+
+#[cfg(test)]
+#[path = "tests/relay_adversarial_tests.rs"]
+mod adversarial_tests;
+
+#[cfg(test)]
+#[path = "tests/relay_quota_boundary_blackhat_tests.rs"]
+mod relay_quota_boundary_blackhat_tests;
+
+#[cfg(test)]
+#[path = "tests/relay_quota_model_adversarial_tests.rs"]
+mod relay_quota_model_adversarial_tests;
+
+#[cfg(test)]
+#[path = "tests/relay_quota_overflow_regression_tests.rs"]
+mod relay_quota_overflow_regression_tests;
+
+#[cfg(test)]
+#[path = "tests/relay_quota_extended_attack_surface_security_tests.rs"]
+mod relay_quota_extended_attack_surface_security_tests;
+
+#[cfg(test)]
+#[path = "tests/relay_watchdog_delta_security_tests.rs"]
+mod relay_watchdog_delta_security_tests;
+
+#[cfg(test)]
+#[path = "tests/relay_atomic_quota_invariant_tests.rs"]
+mod relay_atomic_quota_invariant_tests;

src/proxy/route_mode.rs

@@ -1,10 +1,10 @@
 use std::sync::Arc;
-use std::sync::atomic::{AtomicU8, AtomicU64, Ordering};
+use std::sync::atomic::{AtomicU64, Ordering};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
 use tokio::sync::watch;
 
-pub(crate) const ROUTE_SWITCH_ERROR_MSG: &str = "Route mode switched by cutover";
+pub(crate) const ROUTE_SWITCH_ERROR_MSG: &str = "Session terminated";
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 #[repr(u8)]
@@ -14,17 +14,6 @@ pub(crate) enum RelayRouteMode {
 }
 
 impl RelayRouteMode {
-    pub(crate) fn as_u8(self) -> u8 {
-        self as u8
-    }
-
-    pub(crate) fn from_u8(value: u8) -> Self {
-        match value {
-            1 => Self::Middle,
-            _ => Self::Direct,
-        }
-    }
-
     pub(crate) fn as_str(self) -> &'static str {
         match self {
             Self::Direct => "direct",
@@ -41,8 +30,6 @@ pub(crate) struct RouteCutoverState {
 
 #[derive(Clone)]
 pub(crate) struct RouteRuntimeController {
-    mode: Arc<AtomicU8>,
-    generation: Arc<AtomicU64>,
     direct_since_epoch_secs: Arc<AtomicU64>,
     tx: watch::Sender<RouteCutoverState>,
 }
@@ -60,18 +47,13 @@ impl RouteRuntimeController {
             0
         };
         Self {
-            mode: Arc::new(AtomicU8::new(initial_mode.as_u8())),
-            generation: Arc::new(AtomicU64::new(0)),
             direct_since_epoch_secs: Arc::new(AtomicU64::new(direct_since_epoch_secs)),
             tx,
         }
     }
 
     pub(crate) fn snapshot(&self) -> RouteCutoverState {
-        RouteCutoverState {
-            mode: RelayRouteMode::from_u8(self.mode.load(Ordering::Relaxed)),
-            generation: self.generation.load(Ordering::Relaxed),
-        }
+        *self.tx.borrow()
     }
 
     pub(crate) fn subscribe(&self) -> watch::Receiver<RouteCutoverState> {
@@ -84,9 +66,10 @@ impl RouteRuntimeController {
     }
 
     pub(crate) fn set_mode(&self, mode: RelayRouteMode) -> Option<RouteCutoverState> {
-        let previous = self.mode.swap(mode.as_u8(), Ordering::Relaxed);
-        if previous == mode.as_u8() {
-            return None;
+        let mut next = None;
+        let changed = self.tx.send_if_modified(|state| {
+            if state.mode == mode {
+                return false;
             }
             if matches!(mode, RelayRouteMode::Direct) {
                 self.direct_since_epoch_secs
@@ -94,10 +77,17 @@ impl RouteRuntimeController {
             } else {
                 self.direct_since_epoch_secs.store(0, Ordering::Relaxed);
             }
-        let generation = self.generation.fetch_add(1, Ordering::Relaxed) + 1;
-        let next = RouteCutoverState { mode, generation };
-        self.tx.send_replace(next);
-        Some(next)
+            state.mode = mode;
+            state.generation = state.generation.saturating_add(1);
+            next = Some(*state);
+            true
+        });
+
+        if !changed {
+            return None;
+        }
+
+        next
     }
 }
 
@@ -110,10 +100,10 @@ fn now_epoch_secs() -> u64 {
 
 pub(crate) fn is_session_affected_by_cutover(
     current: RouteCutoverState,
-    _session_mode: RelayRouteMode,
+    session_mode: RelayRouteMode,
     session_generation: u64,
 ) -> bool {
-    current.generation > session_generation
+    current.generation > session_generation && current.mode != session_mode
 }
 
 pub(crate) fn affected_cutover_state(
@@ -129,9 +119,7 @@ pub(crate) fn affected_cutover_state(
 }
 
 pub(crate) fn cutover_stagger_delay(session_id: u64, generation: u64) -> Duration {
-    let mut value = session_id
-        ^ generation.rotate_left(17)
-        ^ 0x9e37_79b9_7f4a_7c15;
+    let mut value = session_id ^ generation.rotate_left(17) ^ 0x9e37_79b9_7f4a_7c15;
     value ^= value >> 30;
     value = value.wrapping_mul(0xbf58_476d_1ce4_e5b9);
     value ^= value >> 27;
@@ -140,3 +128,11 @@ pub(crate) fn cutover_stagger_delay(session_id: u64, generation: u64) -> Duratio
     let ms = 1000 + (value % 1000);
     Duration::from_millis(ms)
 }
+
+#[cfg(test)]
+#[path = "tests/route_mode_security_tests.rs"]
+mod security_tests;
+
+#[cfg(test)]
+#[path = "tests/route_mode_coherence_adversarial_tests.rs"]
+mod coherence_adversarial_tests;

src/proxy/session_eviction.rs

@@ -1,3 +1,5 @@
+#![allow(dead_code)]
+
 /// Session eviction is intentionally disabled in runtime.
 ///
 /// The initial `user+dc` single-lease model caused valid parallel client

src/proxy/tests/client_adversarial_tests.rs

@@ -0,0 +1,714 @@
+use super::*;
+use crate::config::ProxyConfig;
+use crate::error::ProxyError;
+use crate::ip_tracker::UserIpTracker;
+use crate::stats::Stats;
+use std::net::{IpAddr, Ipv4Addr, SocketAddr};
+use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+// ------------------------------------------------------------------
+// Priority 3: Massive Concurrency Stress (OWASP ASVS 5.1.6)
+// ------------------------------------------------------------------
+
+#[tokio::test]
+async fn client_stress_10k_connections_limit_strict() {
+    let user = "stress-user";
+    let limit = 512;
+
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+
+    let mut config = ProxyConfig::default();
+    config
+        .access
+        .user_max_tcp_conns
+        .insert(user.to_string(), limit);
+
+    let iterations = 1000;
+    let mut tasks = Vec::new();
+
+    for i in 0..iterations {
+        let stats = Arc::clone(&stats);
+        let ip_tracker = Arc::clone(&ip_tracker);
+        let config = config.clone();
+        let user_str = user.to_string();
+
+        tasks.push(tokio::spawn(async move {
+            let peer = SocketAddr::new(
+                IpAddr::V4(Ipv4Addr::new(127, 0, 0, (i % 254 + 1) as u8)),
+                10000 + (i % 1000) as u16,
+            );
+
+            match RunningClientHandler::acquire_user_connection_reservation_static(
+                &user_str, &config, stats, peer, ip_tracker,
+            )
+            .await
+            {
+                Ok(res) => Ok(res),
+                Err(ProxyError::ConnectionLimitExceeded { .. }) => Err(()),
+                Err(e) => panic!("Unexpected error: {:?}", e),
+            }
+        }));
+    }
+
+    let results = futures::future::join_all(tasks).await;
+    let mut successes = 0;
+    let mut failures = 0;
+    let mut reservations = Vec::new();
+
+    for res in results {
+        match res.unwrap() {
+            Ok(r) => {
+                successes += 1;
+                reservations.push(r);
+            }
+            Err(_) => failures += 1,
+        }
+    }
+
+    assert_eq!(successes, limit, "Should allow exactly 'limit' connections");
+    assert_eq!(
+        failures,
+        iterations - limit,
+        "Should fail the rest with LimitExceeded"
+    );
+    assert_eq!(stats.get_user_curr_connects(user), limit as u64);
+
+    drop(reservations);
+
+    ip_tracker.drain_cleanup_queue().await;
+
+    assert_eq!(
+        stats.get_user_curr_connects(user),
+        0,
+        "Stats must converge to 0 after all drops"
+    );
+    assert_eq!(
+        ip_tracker.get_active_ip_count(user).await,
+        0,
+        "IP tracker must converge to 0"
+    );
+}
+
+// ------------------------------------------------------------------
+// Priority 3: IP Tracker Race Stress
+// ------------------------------------------------------------------
+
+#[tokio::test]
+async fn client_ip_tracker_race_condition_stress() {
+    let user = "race-user";
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 100).await;
+
+    let iterations = 1000;
+    let mut tasks = Vec::new();
+
+    for i in 0..iterations {
+        let ip_tracker = Arc::clone(&ip_tracker);
+        let ip = IpAddr::V4(Ipv4Addr::new(10, 0, 0, (i % 254 + 1) as u8));
+
+        tasks.push(tokio::spawn(async move {
+            for _ in 0..10 {
+                if let Ok(()) = ip_tracker.check_and_add("race-user", ip).await {
+                    ip_tracker.remove_ip("race-user", ip).await;
+                }
+            }
+        }));
+    }
+
+    futures::future::join_all(tasks).await;
+
+    assert_eq!(
+        ip_tracker.get_active_ip_count(user).await,
+        0,
+        "IP count must be zero after balanced add/remove burst"
+    );
+}
+
+#[tokio::test]
+async fn client_limit_burst_peak_never_exceeds_cap() {
+    let user = "peak-cap-user";
+    let limit = 32;
+    let attempts = 256;
+
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+
+    let mut config = ProxyConfig::default();
+    config
+        .access
+        .user_max_tcp_conns
+        .insert(user.to_string(), limit);
+
+    let peak = Arc::new(AtomicU64::new(0));
+    let mut tasks = Vec::with_capacity(attempts);
+
+    for i in 0..attempts {
+        let stats = Arc::clone(&stats);
+        let ip_tracker = Arc::clone(&ip_tracker);
+        let config = config.clone();
+        let peak = Arc::clone(&peak);
+
+        tasks.push(tokio::spawn(async move {
+            let peer = SocketAddr::new(
+                IpAddr::V4(Ipv4Addr::new(203, 0, 113, (i % 250 + 1) as u8)),
+                20000 + i as u16,
+            );
+
+            let acquired = RunningClientHandler::acquire_user_connection_reservation_static(
+                user,
+                &config,
+                stats.clone(),
+                peer,
+                ip_tracker,
+            )
+            .await;
+
+            if let Ok(reservation) = acquired {
+                let now = stats.get_user_curr_connects(user);
+                loop {
+                    let prev = peak.load(Ordering::Relaxed);
+                    if now <= prev {
+                        break;
+                    }
+                    if peak
+                        .compare_exchange(prev, now, Ordering::Relaxed, Ordering::Relaxed)
+                        .is_ok()
+                    {
+                        break;
+                    }
+                }
+                tokio::time::sleep(Duration::from_millis(2)).await;
+                drop(reservation);
+            }
+        }));
+    }
+
+    futures::future::join_all(tasks).await;
+    ip_tracker.drain_cleanup_queue().await;
+
+    assert!(
+        peak.load(Ordering::Relaxed) <= limit as u64,
+        "peak concurrent reservations must not exceed configured cap"
+    );
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}
+
+#[tokio::test]
+async fn client_quota_rejection_never_mutates_live_counters() {
+    let user = "quota-reject-user";
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+
+    let mut config = ProxyConfig::default();
+    config.access.user_data_quota.insert(user.to_string(), 0);
+
+    let peer: SocketAddr = "198.51.100.201:31111".parse().unwrap();
+    let res = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        peer,
+        ip_tracker.clone(),
+    )
+    .await;
+
+    assert!(matches!(res, Err(ProxyError::DataQuotaExceeded { .. })));
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}
+
+#[tokio::test]
+async fn client_expiration_rejection_never_mutates_live_counters() {
+    let user = "expired-user";
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+
+    let mut config = ProxyConfig::default();
+    config.access.user_expirations.insert(
+        user.to_string(),
+        chrono::Utc::now() - chrono::Duration::seconds(1),
+    );
+
+    let peer: SocketAddr = "198.51.100.202:31112".parse().unwrap();
+    let res = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        peer,
+        ip_tracker.clone(),
+    )
+    .await;
+
+    assert!(matches!(res, Err(ProxyError::UserExpired { .. })));
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}
+
+#[tokio::test]
+async fn client_ip_limit_failure_rolls_back_counter_exactly() {
+    let user = "ip-limit-rollback-user";
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 1).await;
+
+    let mut config = ProxyConfig::default();
+    config
+        .access
+        .user_max_tcp_conns
+        .insert(user.to_string(), 16);
+
+    let first_peer: SocketAddr = "198.51.100.203:31113".parse().unwrap();
+    let first = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        first_peer,
+        ip_tracker.clone(),
+    )
+    .await
+    .unwrap();
+
+    let second_peer: SocketAddr = "198.51.100.204:31114".parse().unwrap();
+    let second = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        second_peer,
+        ip_tracker.clone(),
+    )
+    .await;
+
+    assert!(matches!(
+        second,
+        Err(ProxyError::ConnectionLimitExceeded { .. })
+    ));
+    assert_eq!(stats.get_user_curr_connects(user), 1);
+
+    drop(first);
+    ip_tracker.drain_cleanup_queue().await;
+
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}
+
+#[tokio::test]
+async fn client_parallel_limit_checks_success_path_leaves_no_residue() {
+    let user = "parallel-check-success-user";
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 128).await;
+
+    let mut config = ProxyConfig::default();
+    config
+        .access
+        .user_max_tcp_conns
+        .insert(user.to_string(), 128);
+
+    let mut tasks = Vec::new();
+    for i in 0..128u16 {
+        let stats = Arc::clone(&stats);
+        let ip_tracker = Arc::clone(&ip_tracker);
+        let config = config.clone();
+
+        tasks.push(tokio::spawn(async move {
+            let peer = SocketAddr::new(
+                IpAddr::V4(Ipv4Addr::new(10, 10, (i / 255) as u8, (i % 255 + 1) as u8)),
+                32000 + i,
+            );
+            RunningClientHandler::check_user_limits_static(user, &config, &stats, peer, &ip_tracker)
+                .await
+        }));
+    }
+
+    for result in futures::future::join_all(tasks).await {
+        assert!(result.unwrap().is_ok());
+    }
+
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}
+
+#[tokio::test]
+async fn client_parallel_limit_checks_failure_path_leaves_no_residue() {
+    let user = "parallel-check-failure-user";
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 0).await;
+
+    let mut config = ProxyConfig::default();
+    config
+        .access
+        .user_max_tcp_conns
+        .insert(user.to_string(), 512);
+
+    let mut tasks = Vec::new();
+    for i in 0..64u16 {
+        let stats = Arc::clone(&stats);
+        let ip_tracker = Arc::clone(&ip_tracker);
+        let config = config.clone();
+
+        tasks.push(tokio::spawn(async move {
+            let peer = SocketAddr::new(
+                IpAddr::V4(Ipv4Addr::new(172, 16, 0, (i % 250 + 1) as u8)),
+                33000 + i,
+            );
+            RunningClientHandler::check_user_limits_static(user, &config, &stats, peer, &ip_tracker)
+                .await
+        }));
+    }
+
+    let mut _denied = 0usize;
+    for result in futures::future::join_all(tasks).await {
+        match result.unwrap() {
+            Ok(()) => {}
+            Err(ProxyError::ConnectionLimitExceeded { .. }) => _denied += 1,
+            Err(other) => panic!("unexpected error: {other}"),
+        }
+    }
+
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}
+
+#[tokio::test]
+async fn client_churn_mixed_success_failure_converges_to_zero_state() {
+    let user = "mixed-churn-user";
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 4).await;
+
+    let mut config = ProxyConfig::default();
+    config.access.user_max_tcp_conns.insert(user.to_string(), 8);
+
+    let mut tasks = Vec::new();
+    for i in 0..200u16 {
+        let stats = Arc::clone(&stats);
+        let ip_tracker = Arc::clone(&ip_tracker);
+        let config = config.clone();
+
+        tasks.push(tokio::spawn(async move {
+            let peer = SocketAddr::new(
+                IpAddr::V4(Ipv4Addr::new(192, 0, 2, (i % 16 + 1) as u8)),
+                34000 + (i % 32),
+            );
+            let maybe_res = RunningClientHandler::acquire_user_connection_reservation_static(
+                user, &config, stats, peer, ip_tracker,
+            )
+            .await;
+
+            if let Ok(reservation) = maybe_res {
+                tokio::time::sleep(Duration::from_millis((i % 3) as u64)).await;
+                drop(reservation);
+            }
+        }));
+    }
+
+    futures::future::join_all(tasks).await;
+    ip_tracker.drain_cleanup_queue().await;
+
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}
+
+#[tokio::test]
+async fn client_same_ip_parallel_attempts_allow_at_most_one_when_limit_is_one() {
+    let user = "same-ip-user";
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 1).await;
+
+    let mut config = ProxyConfig::default();
+    config.access.user_max_tcp_conns.insert(user.to_string(), 1);
+
+    let peer: SocketAddr = "203.0.113.44:35555".parse().unwrap();
+    let mut tasks = Vec::new();
+
+    for _ in 0..64 {
+        let stats = Arc::clone(&stats);
+        let ip_tracker = Arc::clone(&ip_tracker);
+        let config = config.clone();
+        tasks.push(tokio::spawn(async move {
+            RunningClientHandler::acquire_user_connection_reservation_static(
+                user, &config, stats, peer, ip_tracker,
+            )
+            .await
+        }));
+    }
+
+    let mut granted = 0usize;
+    let mut reservations = Vec::new();
+    for result in futures::future::join_all(tasks).await {
+        match result.unwrap() {
+            Ok(reservation) => {
+                granted += 1;
+                reservations.push(reservation);
+            }
+            Err(ProxyError::ConnectionLimitExceeded { .. }) => {}
+            Err(other) => panic!("unexpected error: {other}"),
+        }
+    }
+
+    assert_eq!(
+        granted, 1,
+        "only one reservation may be granted for same IP with limit=1"
+    );
+    drop(reservations);
+    ip_tracker.drain_cleanup_queue().await;
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}
+
+#[tokio::test]
+async fn client_repeat_acquire_release_cycles_never_accumulate_state() {
+    let user = "repeat-cycle-user";
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 32).await;
+
+    let mut config = ProxyConfig::default();
+    config
+        .access
+        .user_max_tcp_conns
+        .insert(user.to_string(), 32);
+
+    for i in 0..500u16 {
+        let peer = SocketAddr::new(
+            IpAddr::V4(Ipv4Addr::new(198, 18, (i / 250) as u8, (i % 250 + 1) as u8)),
+            36000 + (i % 128),
+        );
+        let reservation = RunningClientHandler::acquire_user_connection_reservation_static(
+            user,
+            &config,
+            stats.clone(),
+            peer,
+            ip_tracker.clone(),
+        )
+        .await
+        .unwrap();
+        drop(reservation);
+    }
+
+    ip_tracker.drain_cleanup_queue().await;
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}
+
+#[tokio::test]
+async fn client_multi_user_isolation_under_parallel_limit_exhaustion() {
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+
+    let mut config = ProxyConfig::default();
+    config.access.user_max_tcp_conns.insert("u1".to_string(), 8);
+    config.access.user_max_tcp_conns.insert("u2".to_string(), 8);
+
+    let mut tasks = Vec::new();
+    for i in 0..128u16 {
+        let stats = Arc::clone(&stats);
+        let ip_tracker = Arc::clone(&ip_tracker);
+        let config = config.clone();
+        tasks.push(tokio::spawn(async move {
+            let user = if i % 2 == 0 { "u1" } else { "u2" };
+            let peer = SocketAddr::new(
+                IpAddr::V4(Ipv4Addr::new(100, 64, (i / 64) as u8, (i % 64 + 1) as u8)),
+                37000 + i,
+            );
+            RunningClientHandler::acquire_user_connection_reservation_static(
+                user, &config, stats, peer, ip_tracker,
+            )
+            .await
+        }));
+    }
+
+    let mut u1_success = 0usize;
+    let mut u2_success = 0usize;
+    let mut reservations = Vec::new();
+    for (idx, result) in futures::future::join_all(tasks)
+        .await
+        .into_iter()
+        .enumerate()
+    {
+        let user = if idx % 2 == 0 { "u1" } else { "u2" };
+        match result.unwrap() {
+            Ok(reservation) => {
+                if user == "u1" {
+                    u1_success += 1;
+                } else {
+                    u2_success += 1;
+                }
+                reservations.push(reservation);
+            }
+            Err(ProxyError::ConnectionLimitExceeded { .. }) => {}
+            Err(other) => panic!("unexpected error: {other}"),
+        }
+    }
+
+    assert_eq!(u1_success, 8, "u1 must get exactly its own configured cap");
+    assert_eq!(u2_success, 8, "u2 must get exactly its own configured cap");
+
+    drop(reservations);
+    ip_tracker.drain_cleanup_queue().await;
+    assert_eq!(stats.get_user_curr_connects("u1"), 0);
+    assert_eq!(stats.get_user_curr_connects("u2"), 0);
+}
+
+#[tokio::test]
+async fn client_limit_recovery_after_full_rejection_wave() {
+    let user = "recover-user";
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 1).await;
+
+    let mut config = ProxyConfig::default();
+    config.access.user_max_tcp_conns.insert(user.to_string(), 1);
+
+    let first_peer: SocketAddr = "198.51.100.50:38001".parse().unwrap();
+    let reservation = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        first_peer,
+        ip_tracker.clone(),
+    )
+    .await
+    .unwrap();
+
+    for i in 0..64u16 {
+        let peer = SocketAddr::new(
+            IpAddr::V4(Ipv4Addr::new(198, 51, 100, (i % 60 + 1) as u8)),
+            38002 + i,
+        );
+        let denied = RunningClientHandler::acquire_user_connection_reservation_static(
+            user,
+            &config,
+            stats.clone(),
+            peer,
+            ip_tracker.clone(),
+        )
+        .await;
+        assert!(matches!(
+            denied,
+            Err(ProxyError::ConnectionLimitExceeded { .. })
+        ));
+    }
+
+    drop(reservation);
+    ip_tracker.drain_cleanup_queue().await;
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+
+    let recovery_peer: SocketAddr = "198.51.100.200:38999".parse().unwrap();
+    let recovered = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        recovery_peer,
+        ip_tracker.clone(),
+    )
+    .await;
+    assert!(
+        recovered.is_ok(),
+        "capacity must recover after prior holder drops"
+    );
+}
+
+#[tokio::test]
+async fn client_dual_limit_cross_product_never_leaks_on_reject() {
+    let user = "dual-limit-user";
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 2).await;
+
+    let mut config = ProxyConfig::default();
+    config.access.user_max_tcp_conns.insert(user.to_string(), 2);
+
+    let p1: SocketAddr = "203.0.113.10:39001".parse().unwrap();
+    let p2: SocketAddr = "203.0.113.11:39002".parse().unwrap();
+    let r1 = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        p1,
+        ip_tracker.clone(),
+    )
+    .await
+    .unwrap();
+    let r2 = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        p2,
+        ip_tracker.clone(),
+    )
+    .await
+    .unwrap();
+
+    for i in 0..32u16 {
+        let peer = SocketAddr::new(
+            IpAddr::V4(Ipv4Addr::new(203, 0, 113, (50 + i) as u8)),
+            39010 + i,
+        );
+        let denied = RunningClientHandler::acquire_user_connection_reservation_static(
+            user,
+            &config,
+            stats.clone(),
+            peer,
+            ip_tracker.clone(),
+        )
+        .await;
+        assert!(matches!(
+            denied,
+            Err(ProxyError::ConnectionLimitExceeded { .. })
+        ));
+    }
+
+    assert_eq!(stats.get_user_curr_connects(user), 2);
+    drop((r1, r2));
+    ip_tracker.drain_cleanup_queue().await;
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}
+
+#[tokio::test]
+async fn client_check_user_limits_concurrent_churn_no_counter_drift() {
+    let user = "check-drift-user";
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 64).await;
+
+    let mut config = ProxyConfig::default();
+    config
+        .access
+        .user_max_tcp_conns
+        .insert(user.to_string(), 64);
+
+    let mut tasks = Vec::new();
+    for i in 0..512u16 {
+        let stats = Arc::clone(&stats);
+        let ip_tracker = Arc::clone(&ip_tracker);
+        let config = config.clone();
+        tasks.push(tokio::spawn(async move {
+            let peer = SocketAddr::new(
+                IpAddr::V4(Ipv4Addr::new(172, 20, (i / 255) as u8, (i % 255 + 1) as u8)),
+                40000 + (i % 500),
+            );
+            let _ = RunningClientHandler::check_user_limits_static(
+                user,
+                &config,
+                &stats,
+                peer,
+                &ip_tracker,
+            )
+            .await;
+        }));
+    }
+
+    for task in futures::future::join_all(tasks).await {
+        task.unwrap();
+    }
+
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}

src/proxy/tests/client_beobachten_ttl_bounds_security_tests.rs

@@ -0,0 +1,126 @@
+use super::*;
+
+const BEOBACHTEN_TTL_MAX_MINUTES: u64 = 24 * 60;
+
+#[test]
+fn beobachten_ttl_exact_upper_bound_is_preserved() {
+    let mut config = ProxyConfig::default();
+    config.general.beobachten = true;
+    config.general.beobachten_minutes = BEOBACHTEN_TTL_MAX_MINUTES;
+
+    let ttl = beobachten_ttl(&config);
+    assert_eq!(
+        ttl,
+        Duration::from_secs(BEOBACHTEN_TTL_MAX_MINUTES * 60),
+        "upper-bound TTL should remain unchanged"
+    );
+}
+
+#[test]
+fn beobachten_ttl_above_upper_bound_is_clamped() {
+    let mut config = ProxyConfig::default();
+    config.general.beobachten = true;
+    config.general.beobachten_minutes = BEOBACHTEN_TTL_MAX_MINUTES + 1;
+
+    let ttl = beobachten_ttl(&config);
+    assert_eq!(
+        ttl,
+        Duration::from_secs(BEOBACHTEN_TTL_MAX_MINUTES * 60),
+        "TTL above security cap must be clamped"
+    );
+}
+
+#[test]
+fn beobachten_ttl_u64_max_is_clamped_fail_safe() {
+    let mut config = ProxyConfig::default();
+    config.general.beobachten = true;
+    config.general.beobachten_minutes = u64::MAX;
+
+    let ttl = beobachten_ttl(&config);
+    assert_eq!(
+        ttl,
+        Duration::from_secs(BEOBACHTEN_TTL_MAX_MINUTES * 60),
+        "extreme configured TTL must not become multi-century retention"
+    );
+}
+
+#[test]
+fn positive_one_minute_maps_to_exact_60_seconds() {
+    let mut config = ProxyConfig::default();
+    config.general.beobachten = true;
+    config.general.beobachten_minutes = 1;
+
+    assert_eq!(beobachten_ttl(&config), Duration::from_secs(60));
+}
+
+#[test]
+fn adversarial_boundary_triplet_behaves_deterministically() {
+    let mut config = ProxyConfig::default();
+    config.general.beobachten = true;
+
+    config.general.beobachten_minutes = BEOBACHTEN_TTL_MAX_MINUTES - 1;
+    assert_eq!(
+        beobachten_ttl(&config),
+        Duration::from_secs((BEOBACHTEN_TTL_MAX_MINUTES - 1) * 60)
+    );
+
+    config.general.beobachten_minutes = BEOBACHTEN_TTL_MAX_MINUTES;
+    assert_eq!(
+        beobachten_ttl(&config),
+        Duration::from_secs(BEOBACHTEN_TTL_MAX_MINUTES * 60)
+    );
+
+    config.general.beobachten_minutes = BEOBACHTEN_TTL_MAX_MINUTES + 1;
+    assert_eq!(
+        beobachten_ttl(&config),
+        Duration::from_secs(BEOBACHTEN_TTL_MAX_MINUTES * 60)
+    );
+}
+
+#[test]
+fn light_fuzz_random_minutes_match_fail_safe_model() {
+    let mut config = ProxyConfig::default();
+    config.general.beobachten = true;
+
+    let mut seed = 0xD15E_A5E5_F00D_BAADu64;
+    for _ in 0..8192 {
+        seed ^= seed << 7;
+        seed ^= seed >> 9;
+        seed ^= seed << 8;
+
+        config.general.beobachten_minutes = seed;
+        let ttl = beobachten_ttl(&config);
+        let expected = if seed == 0 {
+            Duration::from_secs(60)
+        } else {
+            Duration::from_secs(seed.min(BEOBACHTEN_TTL_MAX_MINUTES) * 60)
+        };
+
+        assert_eq!(ttl, expected, "ttl mismatch for minutes={seed}");
+        assert!(ttl <= Duration::from_secs(BEOBACHTEN_TTL_MAX_MINUTES * 60));
+    }
+}
+
+#[test]
+fn stress_monotonic_minutes_remain_monotonic_until_cap_then_flat() {
+    let mut config = ProxyConfig::default();
+    config.general.beobachten = true;
+
+    let mut prev = Duration::from_secs(0);
+    for minutes in 0..=(BEOBACHTEN_TTL_MAX_MINUTES + 4096) {
+        config.general.beobachten_minutes = minutes;
+        let ttl = beobachten_ttl(&config);
+
+        assert!(ttl >= prev, "ttl must be non-decreasing as minutes grow");
+        assert!(ttl <= Duration::from_secs(BEOBACHTEN_TTL_MAX_MINUTES * 60));
+
+        if minutes > BEOBACHTEN_TTL_MAX_MINUTES {
+            assert_eq!(
+                ttl,
+                Duration::from_secs(BEOBACHTEN_TTL_MAX_MINUTES * 60),
+                "ttl must stay clamped once cap is exceeded"
+            );
+        }
+        prev = ttl;
+    }
+}

src/proxy/tests/client_clever_advanced_tests.rs

@@ -0,0 +1,467 @@
+use super::*;
+use crate::config::{ProxyConfig, UpstreamConfig, UpstreamType};
+use crate::protocol::constants::{MAX_TLS_PLAINTEXT_SIZE, MIN_TLS_CLIENT_HELLO_SIZE};
+use crate::stats::Stats;
+use crate::transport::UpstreamManager;
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
+use std::pin::Pin;
+use std::sync::Arc;
+use std::task::{Context, Poll};
+use std::time::Duration;
+use tokio::io::{AsyncRead, AsyncReadExt, AsyncWriteExt, ReadBuf, duplex};
+use tokio::net::TcpListener;
+
+#[test]
+fn edge_mask_reject_delay_min_greater_than_max_does_not_panic() {
+    let mut config = ProxyConfig::default();
+    config.censorship.server_hello_delay_min_ms = 5000;
+    config.censorship.server_hello_delay_max_ms = 1000;
+
+    let rt = tokio::runtime::Runtime::new().unwrap();
+    rt.block_on(async {
+        let start = std::time::Instant::now();
+        maybe_apply_mask_reject_delay(&config).await;
+        let elapsed = start.elapsed();
+
+        assert!(elapsed >= Duration::from_millis(1000));
+        assert!(elapsed < Duration::from_millis(1500));
+    });
+}
+
+#[test]
+fn edge_handshake_timeout_with_mask_grace_saturating_add_prevents_overflow() {
+    let mut config = ProxyConfig::default();
+    config.timeouts.client_handshake = u64::MAX;
+    config.censorship.mask = true;
+
+    let timeout = handshake_timeout_with_mask_grace(&config);
+    assert_eq!(timeout.as_secs(), u64::MAX);
+}
+
+#[test]
+fn edge_tls_clienthello_len_in_bounds_exact_boundaries() {
+    assert!(tls_clienthello_len_in_bounds(MIN_TLS_CLIENT_HELLO_SIZE));
+    assert!(!tls_clienthello_len_in_bounds(
+        MIN_TLS_CLIENT_HELLO_SIZE - 1
+    ));
+    assert!(tls_clienthello_len_in_bounds(MAX_TLS_PLAINTEXT_SIZE));
+    assert!(!tls_clienthello_len_in_bounds(MAX_TLS_PLAINTEXT_SIZE + 1));
+}
+
+#[test]
+fn edge_synthetic_local_addr_boundaries() {
+    assert_eq!(synthetic_local_addr(0).port(), 0);
+    assert_eq!(synthetic_local_addr(80).port(), 80);
+    assert_eq!(synthetic_local_addr(u16::MAX).port(), u16::MAX);
+}
+
+#[test]
+fn edge_beobachten_record_handshake_failure_class_stream_error_eof() {
+    let beobachten = BeobachtenStore::new();
+    let mut config = ProxyConfig::default();
+    config.general.beobachten = true;
+    config.general.beobachten_minutes = 1;
+
+    let eof_err = ProxyError::Stream(crate::error::StreamError::UnexpectedEof);
+    let peer_ip: IpAddr = "198.51.100.100".parse().unwrap();
+
+    record_handshake_failure_class(&beobachten, &config, peer_ip, &eof_err);
+
+    let snapshot = beobachten.snapshot_text(Duration::from_secs(60));
+    assert!(snapshot.contains("[expected_64_got_0]"));
+}
+
+#[tokio::test]
+async fn adversarial_tls_handshake_timeout_during_masking_delay() {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.timeouts.client_handshake = 1;
+    cfg.censorship.mask = true;
+    cfg.censorship.server_hello_delay_min_ms = 3000;
+    cfg.censorship.server_hello_delay_max_ms = 3000;
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+    let (server_side, mut client_side) = duplex(4096);
+
+    let handle = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.1:55000".parse().unwrap(),
+        config,
+        stats.clone(),
+        Arc::new(UpstreamManager::new(
+            vec![],
+            1,
+            1,
+            1,
+            1,
+            false,
+            stats.clone(),
+        )),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    client_side
+        .write_all(&[0x16, 0x03, 0x01, 0xFF, 0xFF])
+        .await
+        .unwrap();
+
+    let result = tokio::time::timeout(Duration::from_secs(4), handle)
+        .await
+        .unwrap()
+        .unwrap();
+
+    assert!(matches!(result, Err(ProxyError::TgHandshakeTimeout)));
+    assert_eq!(stats.get_handshake_timeouts(), 1);
+}
+
+#[tokio::test]
+async fn blackhat_proxy_protocol_slowloris_timeout() {
+    let mut cfg = ProxyConfig::default();
+    cfg.server.proxy_protocol_header_timeout_ms = 200;
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+
+    let (server_side, mut client_side) = duplex(4096);
+    let handle = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.2:55000".parse().unwrap(),
+        config,
+        stats.clone(),
+        Arc::new(UpstreamManager::new(
+            vec![],
+            1,
+            1,
+            1,
+            1,
+            false,
+            stats.clone(),
+        )),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        true,
+    ));
+
+    client_side.write_all(b"PROXY TCP4 192.").await.unwrap();
+    tokio::time::sleep(Duration::from_millis(300)).await;
+
+    let result = tokio::time::timeout(Duration::from_secs(2), handle)
+        .await
+        .unwrap()
+        .unwrap();
+
+    assert!(matches!(result, Err(ProxyError::InvalidProxyProtocol)));
+    assert_eq!(stats.get_connects_bad(), 1);
+}
+
+#[test]
+fn blackhat_ipv4_mapped_ipv6_proxy_source_bypass_attempt() {
+    let trusted = vec!["192.0.2.0/24".parse().unwrap()];
+    let peer_ip = IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc000, 0x0201));
+    assert!(!is_trusted_proxy_source(peer_ip, &trusted));
+}
+
+#[tokio::test]
+async fn negative_proxy_protocol_enabled_but_client_sends_tls_hello() {
+    let mut cfg = ProxyConfig::default();
+    cfg.server.proxy_protocol_header_timeout_ms = 500;
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+
+    let (server_side, mut client_side) = duplex(4096);
+    let handle = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.3:55000".parse().unwrap(),
+        config,
+        stats.clone(),
+        Arc::new(UpstreamManager::new(
+            vec![],
+            1,
+            1,
+            1,
+            1,
+            false,
+            stats.clone(),
+        )),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        true,
+    ));
+
+    client_side
+        .write_all(&[0x16, 0x03, 0x01, 0x02, 0x00])
+        .await
+        .unwrap();
+
+    let result = tokio::time::timeout(Duration::from_secs(2), handle)
+        .await
+        .unwrap()
+        .unwrap();
+
+    assert!(matches!(result, Err(ProxyError::InvalidProxyProtocol)));
+    assert_eq!(stats.get_connects_bad(), 1);
+}
+
+#[tokio::test]
+async fn edge_client_stream_exactly_4_bytes_eof() {
+    let config = Arc::new(ProxyConfig::default());
+    let stats = Arc::new(Stats::new());
+    let beobachten = Arc::new(BeobachtenStore::new());
+
+    let (server_side, mut client_side) = duplex(4096);
+    let handle = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.4:55000".parse().unwrap(),
+        config,
+        stats.clone(),
+        Arc::new(UpstreamManager::new(
+            vec![],
+            1,
+            1,
+            1,
+            1,
+            false,
+            stats.clone(),
+        )),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        beobachten.clone(),
+        false,
+    ));
+
+    client_side
+        .write_all(&[0x16, 0x03, 0x01, 0x00])
+        .await
+        .unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let _ = tokio::time::timeout(Duration::from_secs(2), handle).await;
+
+    let snapshot = beobachten.snapshot_text(Duration::from_secs(60));
+    assert!(snapshot.contains("[expected_64_got_0]"));
+}
+
+#[tokio::test]
+async fn edge_client_stream_tls_header_valid_but_body_1_byte_short_eof() {
+    let config = Arc::new(ProxyConfig::default());
+    let stats = Arc::new(Stats::new());
+
+    let (server_side, mut client_side) = duplex(4096);
+    let handle = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.5:55000".parse().unwrap(),
+        config,
+        stats.clone(),
+        Arc::new(UpstreamManager::new(
+            vec![],
+            1,
+            1,
+            1,
+            1,
+            false,
+            stats.clone(),
+        )),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    client_side
+        .write_all(&[0x16, 0x03, 0x01, 0x00, 100])
+        .await
+        .unwrap();
+    client_side.write_all(&vec![0x41; 99]).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let _ = tokio::time::timeout(Duration::from_secs(2), handle).await;
+    assert_eq!(stats.get_connects_bad(), 1);
+}
+
+#[tokio::test]
+async fn integration_non_tls_modes_disabled_immediately_masks() {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.modes.classic = false;
+    cfg.general.modes.secure = false;
+    cfg.censorship.mask = true;
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+
+    let (server_side, mut client_side) = duplex(4096);
+    let handle = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.6:55000".parse().unwrap(),
+        config,
+        stats.clone(),
+        Arc::new(UpstreamManager::new(
+            vec![],
+            1,
+            1,
+            1,
+            1,
+            false,
+            stats.clone(),
+        )),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    client_side.write_all(b"GET / HTTP/1.1\r\n").await.unwrap();
+    let _ = tokio::time::timeout(Duration::from_secs(2), handle).await;
+    assert_eq!(stats.get_connects_bad(), 1);
+}
+
+struct YieldingReader {
+    data: Vec<u8>,
+    pos: usize,
+    yields_left: usize,
+}
+
+impl AsyncRead for YieldingReader {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<std::io::Result<()>> {
+        let this = self.get_mut();
+        if this.yields_left > 0 {
+            this.yields_left -= 1;
+            cx.waker().wake_by_ref();
+            return Poll::Pending;
+        }
+        if this.pos >= this.data.len() {
+            return Poll::Ready(Ok(()));
+        }
+        buf.put_slice(&this.data[this.pos..this.pos + 1]);
+        this.pos += 1;
+        this.yields_left = 2;
+        Poll::Ready(Ok(()))
+    }
+}
+
+#[tokio::test]
+async fn fuzz_read_with_progress_heavy_yielding() {
+    let expected_data = b"HEAVY_YIELD_TEST_DATA".to_vec();
+    let mut reader = YieldingReader {
+        data: expected_data.clone(),
+        pos: 0,
+        yields_left: 2,
+    };
+
+    let mut buf = vec![0u8; expected_data.len()];
+    let read_bytes = read_with_progress(&mut reader, &mut buf).await.unwrap();
+
+    assert_eq!(read_bytes, expected_data.len());
+    assert_eq!(buf, expected_data);
+}
+
+#[test]
+fn edge_wrap_tls_application_record_exactly_u16_max() {
+    let payload = vec![0u8; 65535];
+    let wrapped = wrap_tls_application_record(&payload);
+    assert_eq!(wrapped.len(), 65540);
+    assert_eq!(wrapped[0], TLS_RECORD_APPLICATION);
+    assert_eq!(&wrapped[3..5], &65535u16.to_be_bytes());
+}
+
+#[test]
+fn fuzz_wrap_tls_application_record_lengths() {
+    let lengths = [0, 1, 65534, 65535, 65536, 131070, 131071, 131072];
+    for len in lengths {
+        let payload = vec![0u8; len];
+        let wrapped = wrap_tls_application_record(&payload);
+        let expected_chunks = len.div_ceil(65535).max(1);
+        assert_eq!(wrapped.len(), len + 5 * expected_chunks);
+    }
+}
+
+#[tokio::test]
+async fn stress_user_connection_reservation_concurrent_same_ip_exhaustion() {
+    let user = "stress-same-ip-user";
+    let mut config = ProxyConfig::default();
+    config.access.user_max_tcp_conns.insert(user.to_string(), 5);
+
+    let config = Arc::new(config);
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 10).await;
+
+    let peer = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(198, 51, 100, 77)), 55000);
+
+    let mut tasks = tokio::task::JoinSet::new();
+    let mut reservations = Vec::new();
+
+    for _ in 0..10 {
+        let config = config.clone();
+        let stats = stats.clone();
+        let ip_tracker = ip_tracker.clone();
+        tasks.spawn(async move {
+            RunningClientHandler::acquire_user_connection_reservation_static(
+                user, &config, stats, peer, ip_tracker,
+            )
+            .await
+        });
+    }
+
+    let mut successes = 0;
+    let mut failures = 0;
+
+    while let Some(res) = tasks.join_next().await {
+        match res.unwrap() {
+            Ok(r) => {
+                successes += 1;
+                reservations.push(r);
+            }
+            Err(_) => failures += 1,
+        }
+    }
+
+    assert_eq!(successes, 5);
+    assert_eq!(failures, 5);
+    assert_eq!(stats.get_user_curr_connects(user), 5);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 1);
+
+    for reservation in reservations {
+        reservation.release().await;
+    }
+
+    assert_eq!(stats.get_user_curr_connects(user), 0);
+    assert_eq!(ip_tracker.get_active_ip_count(user).await, 0);
+}

src/proxy/tests/client_deep_invariants_tests.rs

@@ -0,0 +1,222 @@
+use super::*;
+use crate::config::ProxyConfig;
+use crate::protocol::constants::MIN_TLS_CLIENT_HELLO_SIZE;
+use crate::stats::Stats;
+use crate::transport::UpstreamManager;
+use std::sync::Arc;
+use std::time::Duration;
+use tokio::io::{AsyncWriteExt, duplex};
+
+fn preload_user_quota(stats: &Stats, user: &str, bytes: u64) {
+    let user_stats = stats.get_or_create_user_stats_handle(user);
+    stats.quota_charge_post_write(user_stats.as_ref(), bytes);
+}
+
+#[test]
+fn invariant_wrap_tls_application_record_exact_multiples() {
+    let chunk_size = u16::MAX as usize;
+    let payload = vec![0xAA; chunk_size * 2];
+
+    let wrapped = wrap_tls_application_record(&payload);
+
+    assert_eq!(wrapped.len(), 2 * (5 + chunk_size));
+    assert_eq!(wrapped[0], TLS_RECORD_APPLICATION);
+    assert_eq!(&wrapped[3..5], &65535u16.to_be_bytes());
+
+    let second_header_idx = 5 + chunk_size;
+    assert_eq!(wrapped[second_header_idx], TLS_RECORD_APPLICATION);
+    assert_eq!(
+        &wrapped[second_header_idx + 3..second_header_idx + 5],
+        &65535u16.to_be_bytes()
+    );
+}
+
+#[tokio::test]
+async fn invariant_tls_clienthello_truncation_exact_boundary_triggers_masking() {
+    let config = Arc::new(ProxyConfig::default());
+    let stats = Arc::new(Stats::new());
+
+    let (server_side, mut client_side) = duplex(4096);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.20:55000".parse().unwrap(),
+        config,
+        stats.clone(),
+        Arc::new(UpstreamManager::new(
+            vec![],
+            1,
+            1,
+            1,
+            1,
+            false,
+            stats.clone(),
+        )),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let claimed_len = MIN_TLS_CLIENT_HELLO_SIZE as u16;
+    let mut header = vec![0x16, 0x03, 0x01];
+    header.extend_from_slice(&claimed_len.to_be_bytes());
+
+    client_side.write_all(&header).await.unwrap();
+    client_side
+        .write_all(&vec![0x42; MIN_TLS_CLIENT_HELLO_SIZE - 1])
+        .await
+        .unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let _ = tokio::time::timeout(Duration::from_secs(2), handler)
+        .await
+        .unwrap();
+    assert_eq!(stats.get_connects_bad(), 1);
+}
+
+#[tokio::test]
+async fn invariant_acquire_reservation_ip_limit_rollback() {
+    let user = "rollback-test-user";
+    let mut config = ProxyConfig::default();
+    config
+        .access
+        .user_max_tcp_conns
+        .insert(user.to_string(), 10);
+
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    ip_tracker.set_user_limit(user, 1).await;
+
+    let peer_a = "198.51.100.21:55000".parse().unwrap();
+    let _res_a = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        peer_a,
+        ip_tracker.clone(),
+    )
+    .await
+    .unwrap();
+
+    assert_eq!(stats.get_user_curr_connects(user), 1);
+
+    let peer_b = "203.0.113.22:55000".parse().unwrap();
+    let res_b = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        peer_b,
+        ip_tracker.clone(),
+    )
+    .await;
+
+    assert!(matches!(
+        res_b,
+        Err(ProxyError::ConnectionLimitExceeded { .. })
+    ));
+    assert_eq!(stats.get_user_curr_connects(user), 1);
+}
+
+#[tokio::test]
+async fn invariant_quota_exact_boundary_inclusive() {
+    let user = "quota-strict-user";
+    let mut config = ProxyConfig::default();
+    config.access.user_data_quota.insert(user.to_string(), 1000);
+
+    let stats = Arc::new(Stats::new());
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    let peer = "198.51.100.23:55000".parse().unwrap();
+
+    preload_user_quota(stats.as_ref(), user, 999);
+    let res1 = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        peer,
+        ip_tracker.clone(),
+    )
+    .await;
+    assert!(res1.is_ok());
+    res1.unwrap().release().await;
+
+    preload_user_quota(stats.as_ref(), user, 1);
+    let res2 = RunningClientHandler::acquire_user_connection_reservation_static(
+        user,
+        &config,
+        stats.clone(),
+        peer,
+        ip_tracker.clone(),
+    )
+    .await;
+    assert!(matches!(res2, Err(ProxyError::DataQuotaExceeded { .. })));
+}
+
+#[tokio::test]
+async fn invariant_direct_mode_partial_header_eof_is_error_not_bad_connect() {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = true;
+    cfg.general.beobachten_minutes = 1;
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+    let beobachten = Arc::new(BeobachtenStore::new());
+
+    let (server_side, mut client_side) = duplex(4096);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.25:55000".parse().unwrap(),
+        config,
+        stats.clone(),
+        Arc::new(UpstreamManager::new(
+            vec![],
+            1,
+            1,
+            1,
+            1,
+            false,
+            stats.clone(),
+        )),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        beobachten.clone(),
+        false,
+    ));
+
+    client_side.write_all(&[0xEF, 0xEF, 0xEF]).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let result = tokio::time::timeout(Duration::from_secs(2), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    assert!(result.is_err());
+    assert_eq!(stats.get_connects_bad(), 0);
+    let snapshot = beobachten.snapshot_text(Duration::from_secs(60));
+    assert!(snapshot.contains("[expected_64_got_0]"));
+}
+
+#[tokio::test]
+async fn invariant_route_mode_snapshot_picks_up_latest_mode() {
+    let route_runtime = Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct));
+    assert!(matches!(
+        route_runtime.snapshot().mode,
+        RelayRouteMode::Direct
+    ));
+
+    route_runtime.set_mode(RelayRouteMode::Middle);
+    assert!(matches!(
+        route_runtime.snapshot().mode,
+        RelayRouteMode::Middle
+    ));
+}

src/proxy/tests/client_masking_blackhat_campaign_tests.rs

@@ -0,0 +1,904 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use crate::crypto::sha256_hmac;
+use crate::protocol::constants::{
+    HANDSHAKE_LEN, MAX_TLS_PLAINTEXT_SIZE, MIN_TLS_CLIENT_HELLO_SIZE, TLS_RECORD_APPLICATION,
+    TLS_VERSION,
+};
+use crate::protocol::tls;
+use std::collections::HashSet;
+use std::net::SocketAddr;
+use std::sync::Arc;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+use tokio::time::{Duration, Instant};
+
+struct CampaignHarness {
+    config: Arc<ProxyConfig>,
+    stats: Arc<Stats>,
+    upstream_manager: Arc<UpstreamManager>,
+    replay_checker: Arc<ReplayChecker>,
+    buffer_pool: Arc<BufferPool>,
+    rng: Arc<SecureRandom>,
+    route_runtime: Arc<RouteRuntimeController>,
+    ip_tracker: Arc<UserIpTracker>,
+    beobachten: Arc<BeobachtenStore>,
+}
+
+fn new_upstream_manager(stats: Arc<Stats>) -> Arc<UpstreamManager> {
+    Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats,
+    ))
+}
+
+fn build_mask_harness(secret_hex: &str, mask_port: u16) -> CampaignHarness {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = mask_port;
+    cfg.censorship.mask_proxy_protocol = 0;
+    cfg.access.ignore_time_skew = true;
+    cfg.access
+        .users
+        .insert("user".to_string(), secret_hex.to_string());
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+
+    CampaignHarness {
+        config,
+        stats: stats.clone(),
+        upstream_manager: new_upstream_manager(stats),
+        replay_checker: Arc::new(ReplayChecker::new(1024, Duration::from_secs(60))),
+        buffer_pool: Arc::new(BufferPool::new()),
+        rng: Arc::new(SecureRandom::new()),
+        route_runtime: Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        ip_tracker: Arc::new(UserIpTracker::new()),
+        beobachten: Arc::new(BeobachtenStore::new()),
+    }
+}
+
+fn make_valid_tls_client_hello(secret: &[u8], timestamp: u32, tls_len: usize, fill: u8) -> Vec<u8> {
+    assert!(
+        tls_len <= u16::MAX as usize,
+        "TLS length must fit into record header"
+    );
+
+    let total_len = 5 + tls_len;
+    let mut handshake = vec![fill; total_len];
+
+    handshake[0] = 0x16;
+    handshake[1] = 0x03;
+    handshake[2] = 0x01;
+    handshake[3..5].copy_from_slice(&(tls_len as u16).to_be_bytes());
+
+    let session_id_len: usize = 32;
+    handshake[tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN] = session_id_len as u8;
+
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN].fill(0);
+    let computed = sha256_hmac(secret, &handshake);
+    let mut digest = computed;
+    let ts = timestamp.to_le_bytes();
+    for i in 0..4 {
+        digest[28 + i] ^= ts[i];
+    }
+
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN]
+        .copy_from_slice(&digest);
+    handshake
+}
+
+fn wrap_tls_record(record_type: u8, payload: &[u8]) -> Vec<u8> {
+    let mut record = Vec::with_capacity(5 + payload.len());
+    record.push(record_type);
+    record.extend_from_slice(&TLS_VERSION);
+    record.extend_from_slice(&(payload.len() as u16).to_be_bytes());
+    record.extend_from_slice(payload);
+    record
+}
+
+fn wrap_tls_application_data(payload: &[u8]) -> Vec<u8> {
+    wrap_tls_record(TLS_RECORD_APPLICATION, payload)
+}
+
+async fn read_and_discard_tls_record_body<T>(stream: &mut T, header: [u8; 5])
+where
+    T: tokio::io::AsyncRead + Unpin,
+{
+    let len = u16::from_be_bytes([header[3], header[4]]) as usize;
+    let mut body = vec![0u8; len];
+    stream.read_exact(&mut body).await.unwrap();
+}
+
+async fn run_tls_success_mtproto_fail_capture(
+    harness: CampaignHarness,
+    peer: SocketAddr,
+    client_hello: Vec<u8>,
+    bad_mtproto_record: Vec<u8>,
+    trailing_records: Vec<Vec<u8>>,
+    expected_forward: Vec<u8>,
+) {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = (*harness.config).clone();
+    cfg.censorship.mask_port = backend_addr.port();
+    let cfg = Arc::new(cfg);
+
+    let expected = expected_forward.clone();
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = vec![0u8; expected.len()];
+        stream.read_exact(&mut got).await.unwrap();
+        got
+    });
+
+    let (server_side, mut client_side) = duplex(262144);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        peer,
+        cfg,
+        harness.stats,
+        harness.upstream_manager,
+        harness.replay_checker,
+        harness.buffer_pool,
+        harness.rng,
+        None,
+        harness.route_runtime,
+        None,
+        harness.ip_tracker,
+        harness.beobachten,
+        false,
+    ));
+
+    client_side.write_all(&client_hello).await.unwrap();
+
+    let mut tls_response_head = [0u8; 5];
+    client_side
+        .read_exact(&mut tls_response_head)
+        .await
+        .unwrap();
+    assert_eq!(tls_response_head[0], 0x16);
+    read_and_discard_tls_record_body(&mut client_side, tls_response_head).await;
+
+    client_side.write_all(&bad_mtproto_record).await.unwrap();
+    for record in trailing_records {
+        client_side.write_all(&record).await.unwrap();
+    }
+
+    let got = tokio::time::timeout(Duration::from_secs(4), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(got, expected_forward);
+
+    client_side.shutdown().await.unwrap();
+    let result = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+}
+
+async fn run_invalid_tls_capture(config: Arc<ProxyConfig>, payload: Vec<u8>, expected: Vec<u8>) {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = (*config).clone();
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    let cfg = Arc::new(cfg);
+
+    let expected_probe = expected.clone();
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = vec![0u8; expected_probe.len()];
+        stream.read_exact(&mut got).await.unwrap();
+        got
+    });
+
+    let stats = Arc::new(Stats::new());
+    let (server_side, mut client_side) = duplex(65536);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.77:45001".parse().unwrap(),
+        cfg,
+        stats,
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    client_side.write_all(&payload).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let got = tokio::time::timeout(Duration::from_secs(4), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(got, expected);
+
+    let result = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+}
+
+#[tokio::test]
+async fn blackhat_campaign_01_tail_only_record_is_forwarded_after_tls_success_mtproto_fail() {
+    let secret = [0xA1u8; 16];
+    let harness = build_mask_harness("a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1", 1);
+    let client_hello = make_valid_tls_client_hello(&secret, 11, 600, 0x41);
+    let bad_record = wrap_tls_application_data(&vec![0u8; HANDSHAKE_LEN]);
+    let tail = wrap_tls_application_data(b"blackhat-tail-01");
+
+    run_tls_success_mtproto_fail_capture(
+        harness,
+        "198.51.100.1:55001".parse().unwrap(),
+        client_hello,
+        bad_record,
+        vec![tail.clone()],
+        tail,
+    )
+    .await;
+}
+
+#[tokio::test]
+async fn blackhat_campaign_02_two_ordered_records_preserved_after_fallback() {
+    let secret = [0xA2u8; 16];
+    let harness = build_mask_harness("a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2", 1);
+    let client_hello = make_valid_tls_client_hello(&secret, 12, 600, 0x42);
+    let bad_record = wrap_tls_application_data(&vec![0u8; HANDSHAKE_LEN]);
+    let r1 = wrap_tls_application_data(b"first");
+    let r2 = wrap_tls_application_data(b"second");
+    let expected = [r1.clone(), r2.clone()].concat();
+
+    run_tls_success_mtproto_fail_capture(
+        harness,
+        "198.51.100.2:55002".parse().unwrap(),
+        client_hello,
+        bad_record,
+        vec![r1, r2],
+        expected,
+    )
+    .await;
+}
+
+#[tokio::test]
+async fn blackhat_campaign_03_large_tls_application_record_survives_fallback() {
+    let secret = [0xA3u8; 16];
+    let harness = build_mask_harness("a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3a3", 1);
+    let client_hello = make_valid_tls_client_hello(&secret, 13, 600, 0x43);
+    let bad_record = wrap_tls_application_data(&vec![0u8; HANDSHAKE_LEN]);
+    let big_payload = vec![0x5Au8; MAX_TLS_PLAINTEXT_SIZE];
+    let big_record = wrap_tls_application_data(&big_payload);
+
+    run_tls_success_mtproto_fail_capture(
+        harness,
+        "198.51.100.3:55003".parse().unwrap(),
+        client_hello,
+        bad_record,
+        vec![big_record.clone()],
+        big_record,
+    )
+    .await;
+}
+
+#[tokio::test]
+async fn blackhat_campaign_04_coalesced_tail_in_failed_record_is_reframed_and_forwarded() {
+    let secret = [0xA4u8; 16];
+    let harness = build_mask_harness("a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4a4", 1);
+    let client_hello = make_valid_tls_client_hello(&secret, 14, 600, 0x44);
+
+    let coalesced_tail = b"coalesced-tail-blackhat".to_vec();
+    let mut bad_payload = vec![0u8; HANDSHAKE_LEN];
+    bad_payload.extend_from_slice(&coalesced_tail);
+    let bad_record = wrap_tls_application_data(&bad_payload);
+    let expected = wrap_tls_application_data(&coalesced_tail);
+
+    run_tls_success_mtproto_fail_capture(
+        harness,
+        "198.51.100.4:55004".parse().unwrap(),
+        client_hello,
+        bad_record,
+        Vec::new(),
+        expected,
+    )
+    .await;
+}
+
+#[tokio::test]
+async fn blackhat_campaign_05_coalesced_tail_plus_next_record_keep_wire_order() {
+    let secret = [0xA5u8; 16];
+    let harness = build_mask_harness("a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5", 1);
+    let client_hello = make_valid_tls_client_hello(&secret, 15, 600, 0x45);
+
+    let coalesced_tail = b"inline-tail".to_vec();
+    let mut bad_payload = vec![0u8; HANDSHAKE_LEN];
+    bad_payload.extend_from_slice(&coalesced_tail);
+    let bad_record = wrap_tls_application_data(&bad_payload);
+    let next_record = wrap_tls_application_data(b"next-record");
+
+    let expected = [
+        wrap_tls_application_data(&coalesced_tail),
+        next_record.clone(),
+    ]
+    .concat();
+
+    run_tls_success_mtproto_fail_capture(
+        harness,
+        "198.51.100.5:55005".parse().unwrap(),
+        client_hello,
+        bad_record,
+        vec![next_record],
+        expected,
+    )
+    .await;
+}
+
+#[tokio::test]
+async fn blackhat_campaign_06_replayed_tls_hello_is_masked_without_serverhello() {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let harness = build_mask_harness("a6a6a6a6a6a6a6a6a6a6a6a6a6a6a6a6", backend_addr.port());
+    let replay_checker = harness.replay_checker.clone();
+    let client_hello = make_valid_tls_client_hello(&[0xA6; 16], 16, 600, 0x46);
+    let invalid_mtproto_record = wrap_tls_application_data(&vec![0u8; HANDSHAKE_LEN]);
+    let first_tail = wrap_tls_application_data(b"seed-tail");
+
+    let expected_hello = client_hello.clone();
+    let expected_tail = first_tail.clone();
+
+    let accept_task = tokio::spawn(async move {
+        let (mut s1, _) = listener.accept().await.unwrap();
+        let mut got_tail = vec![0u8; expected_tail.len()];
+        s1.read_exact(&mut got_tail).await.unwrap();
+        assert_eq!(got_tail, expected_tail);
+        drop(s1);
+
+        let (mut s2, _) = listener.accept().await.unwrap();
+        let mut got_hello = vec![0u8; expected_hello.len()];
+        s2.read_exact(&mut got_hello).await.unwrap();
+        got_hello
+    });
+
+    let run_one = |checker: Arc<ReplayChecker>, send_mtproto: bool| {
+        let mut cfg = (*harness.config).clone();
+        cfg.censorship.mask_port = backend_addr.port();
+        let cfg = Arc::new(cfg);
+        let hello = client_hello.clone();
+        let invalid_mtproto_record = invalid_mtproto_record.clone();
+        let first_tail = first_tail.clone();
+        let stats = harness.stats.clone();
+        let upstream = harness.upstream_manager.clone();
+        let pool = harness.buffer_pool.clone();
+        let rng = harness.rng.clone();
+        let route = harness.route_runtime.clone();
+        let ipt = harness.ip_tracker.clone();
+        let beob = harness.beobachten.clone();
+
+        async move {
+            let (server_side, mut client_side) = duplex(131072);
+            let handler = tokio::spawn(handle_client_stream(
+                server_side,
+                "198.51.100.6:55006".parse().unwrap(),
+                cfg,
+                stats,
+                upstream,
+                checker,
+                pool,
+                rng,
+                None,
+                route,
+                None,
+                ipt,
+                beob,
+                false,
+            ));
+
+            client_side.write_all(&hello).await.unwrap();
+            if send_mtproto {
+                let mut head = [0u8; 5];
+                client_side.read_exact(&mut head).await.unwrap();
+                assert_eq!(head[0], 0x16);
+                read_and_discard_tls_record_body(&mut client_side, head).await;
+                client_side
+                    .write_all(&invalid_mtproto_record)
+                    .await
+                    .unwrap();
+                client_side.write_all(&first_tail).await.unwrap();
+            } else {
+                let mut one = [0u8; 1];
+                let no_server_hello = tokio::time::timeout(
+                    Duration::from_millis(300),
+                    client_side.read_exact(&mut one),
+                )
+                .await;
+                assert!(no_server_hello.is_err() || no_server_hello.unwrap().is_err());
+            }
+            client_side.shutdown().await.unwrap();
+            let result = tokio::time::timeout(Duration::from_secs(4), handler)
+                .await
+                .unwrap()
+                .unwrap();
+            assert!(result.is_ok());
+        }
+    };
+
+    run_one(replay_checker.clone(), true).await;
+    run_one(replay_checker, false).await;
+
+    let got = tokio::time::timeout(Duration::from_secs(4), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(got, client_hello);
+}
+
+#[tokio::test]
+async fn blackhat_campaign_07_truncated_clienthello_exact_prefix_is_forwarded() {
+    let mut payload = vec![0u8; 5 + 37];
+    payload[0] = 0x16;
+    payload[1] = 0x03;
+    payload[2] = 0x01;
+    payload[3..5].copy_from_slice(&600u16.to_be_bytes());
+    payload[5..].fill(0x71);
+
+    run_invalid_tls_capture(Arc::new(ProxyConfig::default()), payload.clone(), payload).await;
+}
+
+#[tokio::test]
+async fn blackhat_campaign_08_out_of_bounds_len_forwards_header_only() {
+    let header = vec![0x16, 0x03, 0x01, 0xFF, 0xFF];
+    run_invalid_tls_capture(Arc::new(ProxyConfig::default()), header.clone(), header).await;
+}
+
+#[tokio::test]
+async fn blackhat_campaign_09_fragmented_header_then_partial_body_masks_seen_bytes_only() {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = ProxyConfig::default();
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.censorship.mask_unix_sock = None;
+
+    let expected = {
+        let mut x = vec![0u8; 5 + 11];
+        x[0] = 0x16;
+        x[1] = 0x03;
+        x[2] = 0x01;
+        x[3..5].copy_from_slice(&600u16.to_be_bytes());
+        x[5..].fill(0xCC);
+        x
+    };
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = vec![0u8; expected.len()];
+        stream.read_exact(&mut got).await.unwrap();
+        got
+    });
+
+    let (server_side, mut client_side) = duplex(65536);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.9:55009".parse().unwrap(),
+        Arc::new(cfg),
+        Arc::new(Stats::new()),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    client_side.write_all(&[0x16, 0x03]).await.unwrap();
+    client_side.write_all(&[0x01, 0x02, 0x58]).await.unwrap();
+    client_side.write_all(&vec![0xCC; 11]).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let got = tokio::time::timeout(Duration::from_secs(4), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(got.len(), 16);
+
+    let result = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+}
+
+#[tokio::test]
+async fn blackhat_campaign_10_zero_handshake_timeout_with_delay_still_avoids_timeout_counter() {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = 1;
+    cfg.timeouts.client_handshake = 0;
+    cfg.censorship.server_hello_delay_min_ms = 700;
+    cfg.censorship.server_hello_delay_max_ms = 700;
+
+    let stats = Arc::new(Stats::new());
+    let (server_side, mut client_side) = duplex(4096);
+    let started = Instant::now();
+
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.10:55010".parse().unwrap(),
+        Arc::new(cfg),
+        stats.clone(),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let mut invalid = vec![0u8; 5 + 700];
+    invalid[0] = 0x16;
+    invalid[1] = 0x03;
+    invalid[2] = 0x01;
+    invalid[3..5].copy_from_slice(&700u16.to_be_bytes());
+    invalid[5..].fill(0x66);
+
+    client_side.write_all(&invalid).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let result = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+    assert_eq!(stats.get_handshake_timeouts(), 0);
+    assert!(started.elapsed() >= Duration::from_millis(650));
+}
+
+#[tokio::test]
+async fn blackhat_campaign_11_parallel_bad_tls_probes_all_masked_without_timeouts() {
+    let n = 24usize;
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = ProxyConfig::default();
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_port = backend_addr.port();
+
+    let stats = Arc::new(Stats::new());
+    let accept_task = tokio::spawn(async move {
+        let mut seen = HashSet::new();
+        for _ in 0..n {
+            let (mut stream, _) = listener.accept().await.unwrap();
+            let mut hdr = [0u8; 5];
+            stream.read_exact(&mut hdr).await.unwrap();
+            seen.insert(hdr.to_vec());
+        }
+        seen
+    });
+
+    let mut tasks = Vec::new();
+    for i in 0..n {
+        let mut hdr = [0u8; 5];
+        hdr[0] = 0x16;
+        hdr[1] = 0x03;
+        hdr[2] = 0x01;
+        hdr[3] = 0xFF;
+        hdr[4] = i as u8;
+
+        let cfg = Arc::new(cfg.clone());
+        let stats = stats.clone();
+        tasks.push(tokio::spawn(async move {
+            let (server_side, mut client_side) = duplex(4096);
+            let handler = tokio::spawn(handle_client_stream(
+                server_side,
+                format!("198.51.100.11:{}", 56000 + i).parse().unwrap(),
+                cfg,
+                stats,
+                new_upstream_manager(Arc::new(Stats::new())),
+                Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+                Arc::new(BufferPool::new()),
+                Arc::new(SecureRandom::new()),
+                None,
+                Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+                None,
+                Arc::new(UserIpTracker::new()),
+                Arc::new(BeobachtenStore::new()),
+                false,
+            ));
+            client_side.write_all(&hdr).await.unwrap();
+            client_side.shutdown().await.unwrap();
+            let result = tokio::time::timeout(Duration::from_secs(4), handler)
+                .await
+                .unwrap()
+                .unwrap();
+            assert!(result.is_ok());
+            hdr.to_vec()
+        }));
+    }
+
+    let mut expected = HashSet::new();
+    for t in tasks {
+        expected.insert(t.await.unwrap());
+    }
+
+    let seen = tokio::time::timeout(Duration::from_secs(6), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(seen, expected);
+    assert_eq!(stats.get_handshake_timeouts(), 0);
+}
+
+#[tokio::test]
+async fn blackhat_campaign_12_parallel_tls_success_mtproto_fail_sessions_keep_isolation() {
+    let sessions = 16usize;
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut expected = HashSet::new();
+    for i in 0..sessions {
+        let rec = wrap_tls_application_data(&vec![i as u8; 8 + i]);
+        expected.insert(rec);
+    }
+
+    let accept_task = tokio::spawn(async move {
+        let mut got_set = HashSet::new();
+        for _ in 0..sessions {
+            let (mut stream, _) = listener.accept().await.unwrap();
+            let mut head = [0u8; 5];
+            stream.read_exact(&mut head).await.unwrap();
+            let len = u16::from_be_bytes([head[3], head[4]]) as usize;
+            let mut rec = vec![0u8; 5 + len];
+            rec[..5].copy_from_slice(&head);
+            stream.read_exact(&mut rec[5..]).await.unwrap();
+            got_set.insert(rec);
+        }
+        got_set
+    });
+
+    let mut tasks = Vec::new();
+    for i in 0..sessions {
+        let mut harness =
+            build_mask_harness("abababababababababababababababab", backend_addr.port());
+        let mut cfg = (*harness.config).clone();
+        cfg.censorship.mask_port = backend_addr.port();
+        harness.config = Arc::new(cfg);
+        tasks.push(tokio::spawn(async move {
+            let secret = [0xABu8; 16];
+            let hello =
+                make_valid_tls_client_hello(&secret, 100 + i as u32, 600, 0x40 + (i as u8 % 10));
+            let bad = wrap_tls_application_data(&vec![0u8; HANDSHAKE_LEN]);
+            let tail = wrap_tls_application_data(&vec![i as u8; 8 + i]);
+            let (server_side, mut client_side) = duplex(131072);
+            let handler = tokio::spawn(handle_client_stream(
+                server_side,
+                format!("198.51.100.12:{}", 56100 + i).parse().unwrap(),
+                harness.config,
+                harness.stats,
+                harness.upstream_manager,
+                harness.replay_checker,
+                harness.buffer_pool,
+                harness.rng,
+                None,
+                harness.route_runtime,
+                None,
+                harness.ip_tracker,
+                harness.beobachten,
+                false,
+            ));
+
+            client_side.write_all(&hello).await.unwrap();
+            let mut head = [0u8; 5];
+            client_side.read_exact(&mut head).await.unwrap();
+            read_and_discard_tls_record_body(&mut client_side, head).await;
+            client_side.write_all(&bad).await.unwrap();
+            client_side.write_all(&tail).await.unwrap();
+            client_side.shutdown().await.unwrap();
+
+            let result = tokio::time::timeout(Duration::from_secs(5), handler)
+                .await
+                .unwrap()
+                .unwrap();
+            assert!(result.is_ok());
+            tail
+        }));
+    }
+
+    let mut produced = HashSet::new();
+    for t in tasks {
+        produced.insert(t.await.unwrap());
+    }
+
+    let observed = tokio::time::timeout(Duration::from_secs(8), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+
+    assert_eq!(produced, expected);
+    assert_eq!(observed, expected);
+}
+
+#[tokio::test]
+async fn blackhat_campaign_13_backend_down_does_not_escalate_to_handshake_timeout() {
+    let mut cfg = ProxyConfig::default();
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = 1;
+    cfg.timeouts.client_handshake = 1;
+
+    let stats = Arc::new(Stats::new());
+    let (server_side, mut client_side) = duplex(4096);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.13:55013".parse().unwrap(),
+        Arc::new(cfg),
+        stats.clone(),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let bad = vec![0x16, 0x03, 0x01, 0xFF, 0x00];
+    client_side.write_all(&bad).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let result = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+    assert_eq!(stats.get_handshake_timeouts(), 0);
+}
+
+#[tokio::test]
+async fn blackhat_campaign_14_masking_disabled_path_finishes_cleanly() {
+    let mut cfg = ProxyConfig::default();
+    cfg.censorship.mask = false;
+    cfg.timeouts.client_handshake = 1;
+
+    let stats = Arc::new(Stats::new());
+    let (server_side, mut client_side) = duplex(4096);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.14:55014".parse().unwrap(),
+        Arc::new(cfg),
+        stats.clone(),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let bad = vec![0x16, 0x03, 0x01, 0xFF, 0xF0];
+    client_side.write_all(&bad).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let result = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+    assert_eq!(stats.get_handshake_timeouts(), 0);
+}
+
+#[tokio::test]
+async fn blackhat_campaign_15_light_fuzz_tls_lengths_and_fragmentation() {
+    let mut seed = 0x9E3779B97F4A7C15u64;
+
+    for idx in 0..20u16 {
+        seed = seed.wrapping_mul(6364136223846793005).wrapping_add(1);
+        let mut tls_len = (seed as usize) % 20000;
+        if idx % 3 == 0 {
+            tls_len = MAX_TLS_PLAINTEXT_SIZE + 1 + (tls_len % 1024);
+        }
+
+        let body_to_send =
+            if (MIN_TLS_CLIENT_HELLO_SIZE..=MAX_TLS_PLAINTEXT_SIZE).contains(&tls_len) {
+                (seed as usize % 29).min(tls_len.saturating_sub(1))
+            } else {
+                0
+            };
+
+        let mut probe = vec![0u8; 5 + body_to_send];
+        probe[0] = 0x16;
+        probe[1] = 0x03;
+        probe[2] = 0x01;
+        probe[3..5].copy_from_slice(&(tls_len as u16).to_be_bytes());
+        for b in &mut probe[5..] {
+            seed = seed
+                .wrapping_mul(2862933555777941757)
+                .wrapping_add(3037000493);
+            *b = (seed >> 24) as u8;
+        }
+
+        let expected = probe.clone();
+        run_invalid_tls_capture(Arc::new(ProxyConfig::default()), probe, expected).await;
+    }
+}
+
+#[tokio::test]
+async fn blackhat_campaign_16_mixed_probe_burst_stress_finishes_without_panics() {
+    let cases = 18usize;
+    let mut tasks = Vec::new();
+
+    for i in 0..cases {
+        tasks.push(tokio::spawn(async move {
+            if i % 2 == 0 {
+                let mut probe = vec![0u8; 5 + (i % 13)];
+                probe[0] = 0x16;
+                probe[1] = 0x03;
+                probe[2] = 0x01;
+                probe[3..5].copy_from_slice(&600u16.to_be_bytes());
+                probe[5..].fill((0x90 + i as u8) ^ 0x5A);
+                run_invalid_tls_capture(Arc::new(ProxyConfig::default()), probe.clone(), probe)
+                    .await;
+            } else {
+                let hdr = vec![0x16, 0x03, 0x01, 0xFF, i as u8];
+                run_invalid_tls_capture(Arc::new(ProxyConfig::default()), hdr.clone(), hdr).await;
+            }
+        }));
+    }
+
+    for task in tasks {
+        task.await.unwrap();
+    }
+}

src/proxy/tests/client_masking_budget_security_tests.rs

@@ -0,0 +1,255 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use crate::crypto::sha256_hmac;
+use crate::protocol::constants::{HANDSHAKE_LEN, TLS_VERSION};
+use crate::protocol::tls;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+use tokio::time::{Duration, Instant};
+
+struct PipelineHarness {
+    config: Arc<ProxyConfig>,
+    stats: Arc<Stats>,
+    upstream_manager: Arc<UpstreamManager>,
+    replay_checker: Arc<ReplayChecker>,
+    buffer_pool: Arc<BufferPool>,
+    rng: Arc<SecureRandom>,
+    route_runtime: Arc<RouteRuntimeController>,
+    ip_tracker: Arc<UserIpTracker>,
+    beobachten: Arc<BeobachtenStore>,
+}
+
+fn build_harness(config: ProxyConfig) -> PipelineHarness {
+    let config = Arc::new(config);
+    let stats = Arc::new(Stats::new());
+    let upstream_manager = Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats.clone(),
+    ));
+
+    PipelineHarness {
+        config,
+        stats,
+        upstream_manager,
+        replay_checker: Arc::new(ReplayChecker::new(256, Duration::from_secs(60))),
+        buffer_pool: Arc::new(BufferPool::new()),
+        rng: Arc::new(SecureRandom::new()),
+        route_runtime: Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        ip_tracker: Arc::new(UserIpTracker::new()),
+        beobachten: Arc::new(BeobachtenStore::new()),
+    }
+}
+
+fn make_valid_tls_client_hello(secret: &[u8], timestamp: u32, tls_len: usize, fill: u8) -> Vec<u8> {
+    assert!(
+        tls_len <= u16::MAX as usize,
+        "TLS length must fit into record header"
+    );
+
+    let total_len = 5 + tls_len;
+    let mut handshake = vec![fill; total_len];
+
+    handshake[0] = 0x16;
+    handshake[1] = 0x03;
+    handshake[2] = 0x01;
+    handshake[3..5].copy_from_slice(&(tls_len as u16).to_be_bytes());
+
+    let session_id_len: usize = 32;
+    handshake[tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN] = session_id_len as u8;
+
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN].fill(0);
+    let computed = sha256_hmac(secret, &handshake);
+    let mut digest = computed;
+    let ts = timestamp.to_le_bytes();
+    for i in 0..4 {
+        digest[28 + i] ^= ts[i];
+    }
+
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN]
+        .copy_from_slice(&digest);
+    handshake
+}
+
+fn wrap_tls_application_data(payload: &[u8]) -> Vec<u8> {
+    let mut record = Vec::with_capacity(5 + payload.len());
+    record.push(0x17);
+    record.extend_from_slice(&TLS_VERSION);
+    record.extend_from_slice(&(payload.len() as u16).to_be_bytes());
+    record.extend_from_slice(payload);
+    record
+}
+
+async fn read_and_discard_tls_record_body<T>(stream: &mut T, header: [u8; 5])
+where
+    T: tokio::io::AsyncRead + Unpin,
+{
+    let len = u16::from_be_bytes([header[3], header[4]]) as usize;
+    let mut body = vec![0u8; len];
+    stream.read_exact(&mut body).await.unwrap();
+}
+
+#[tokio::test]
+async fn masking_runs_outside_handshake_timeout_budget_with_high_reject_delay() {
+    let mut config = ProxyConfig::default();
+    config.general.beobachten = false;
+    config.censorship.mask = true;
+    config.censorship.mask_unix_sock = None;
+    config.censorship.mask_host = Some("127.0.0.1".to_string());
+    config.censorship.mask_port = 1;
+    config.timeouts.client_handshake = 0;
+    config.censorship.server_hello_delay_min_ms = 730;
+    config.censorship.server_hello_delay_max_ms = 730;
+
+    let harness = build_harness(config);
+    let stats = harness.stats.clone();
+
+    let (server_side, mut client_side) = duplex(4096);
+    let peer: SocketAddr = "198.51.100.241:56541".parse().unwrap();
+
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        peer,
+        harness.config,
+        harness.stats,
+        harness.upstream_manager,
+        harness.replay_checker,
+        harness.buffer_pool,
+        harness.rng,
+        None,
+        harness.route_runtime,
+        None,
+        harness.ip_tracker,
+        harness.beobachten,
+        false,
+    ));
+
+    let mut invalid_hello = vec![0u8; 5 + 600];
+    invalid_hello[0] = 0x16;
+    invalid_hello[1] = 0x03;
+    invalid_hello[2] = 0x01;
+    invalid_hello[3..5].copy_from_slice(&600u16.to_be_bytes());
+    invalid_hello[5..].fill(0x44);
+
+    let started = Instant::now();
+    client_side.write_all(&invalid_hello).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let result = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    assert!(
+        result.is_ok(),
+        "bad-client fallback must not be canceled by handshake timeout"
+    );
+    assert_eq!(
+        stats.get_handshake_timeouts(),
+        0,
+        "masking fallback path must not increment handshake timeout counter"
+    );
+    assert!(
+        started.elapsed() >= Duration::from_millis(700),
+        "configured reject delay should still be visible before masking"
+    );
+}
+
+#[tokio::test]
+async fn tls_mtproto_bad_client_does_not_reinject_clienthello_into_mask_backend() {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut config = ProxyConfig::default();
+    config.general.beobachten = false;
+    config.censorship.mask = true;
+    config.censorship.mask_unix_sock = None;
+    config.censorship.mask_host = Some("127.0.0.1".to_string());
+    config.censorship.mask_port = backend_addr.port();
+    config.censorship.mask_proxy_protocol = 0;
+    config.access.ignore_time_skew = true;
+    config.access.users.insert(
+        "user".to_string(),
+        "d0d0d0d0d0d0d0d0d0d0d0d0d0d0d0d0".to_string(),
+    );
+
+    let harness = build_harness(config);
+
+    let secret = [0xD0u8; 16];
+    let client_hello = make_valid_tls_client_hello(&secret, 0, 600, 0x41);
+    let invalid_mtproto_record = wrap_tls_application_data(&vec![0u8; HANDSHAKE_LEN]);
+    let trailing_record = wrap_tls_application_data(b"no-clienthello-reinject");
+    let expected_trailing = trailing_record.clone();
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+
+        let mut got = vec![0u8; expected_trailing.len()];
+        stream.read_exact(&mut got).await.unwrap();
+        assert_eq!(
+            got, expected_trailing,
+            "mask backend must receive only post-handshake trailing TLS records"
+        );
+    });
+
+    let (server_side, mut client_side) = duplex(131072);
+    let peer: SocketAddr = "198.51.100.242:56542".parse().unwrap();
+
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        peer,
+        harness.config,
+        harness.stats,
+        harness.upstream_manager,
+        harness.replay_checker,
+        harness.buffer_pool,
+        harness.rng,
+        None,
+        harness.route_runtime,
+        None,
+        harness.ip_tracker,
+        harness.beobachten,
+        false,
+    ));
+
+    client_side.write_all(&client_hello).await.unwrap();
+
+    let mut tls_response_head = [0u8; 5];
+    client_side
+        .read_exact(&mut tls_response_head)
+        .await
+        .unwrap();
+    assert_eq!(tls_response_head[0], 0x16);
+    read_and_discard_tls_record_body(&mut client_side, tls_response_head).await;
+
+    client_side
+        .write_all(&invalid_mtproto_record)
+        .await
+        .unwrap();
+    client_side.write_all(&trailing_record).await.unwrap();
+
+    tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+
+    drop(client_side);
+    let result = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+}

src/proxy/tests/client_masking_diagnostics_security_tests.rs

@@ -0,0 +1,208 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use std::sync::Arc;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+use tokio::time::{Duration, Instant};
+
+fn new_upstream_manager(stats: Arc<Stats>) -> Arc<UpstreamManager> {
+    Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats,
+    ))
+}
+
+fn percentile_ms(mut values: Vec<u128>, p_num: usize, p_den: usize) -> u128 {
+    values.sort_unstable();
+    if values.is_empty() {
+        return 0;
+    }
+    let idx = ((values.len() - 1) * p_num) / p_den;
+    values[idx]
+}
+
+async fn measure_reject_duration_ms(body_sent: usize) -> u128 {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = 1;
+    cfg.timeouts.client_handshake = 1;
+    cfg.censorship.server_hello_delay_min_ms = 700;
+    cfg.censorship.server_hello_delay_max_ms = 700;
+
+    let (server_side, mut client_side) = duplex(65536);
+    let started = Instant::now();
+
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.170:56170".parse().unwrap(),
+        Arc::new(cfg),
+        Arc::new(Stats::new()),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(256, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let mut probe = vec![0u8; 5 + body_sent];
+    probe[0] = 0x16;
+    probe[1] = 0x03;
+    probe[2] = 0x01;
+    probe[3..5].copy_from_slice(&600u16.to_be_bytes());
+    probe[5..].fill(0xA7);
+
+    client_side.write_all(&probe).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let result = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+
+    started.elapsed().as_millis()
+}
+
+async fn capture_forwarded_len(body_sent: usize) -> usize {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.censorship.mask_shape_hardening = false;
+    cfg.timeouts.client_handshake = 1;
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = Vec::new();
+        let _ = tokio::time::timeout(Duration::from_secs(2), stream.read_to_end(&mut got)).await;
+        got.len()
+    });
+
+    let (server_side, mut client_side) = duplex(65536);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.171:56171".parse().unwrap(),
+        Arc::new(cfg),
+        Arc::new(Stats::new()),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(256, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let mut probe = vec![0u8; 5 + body_sent];
+    probe[0] = 0x16;
+    probe[1] = 0x03;
+    probe[2] = 0x01;
+    probe[3..5].copy_from_slice(&600u16.to_be_bytes());
+    probe[5..].fill(0xB4);
+
+    client_side.write_all(&probe).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let result = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+
+    tokio::time::timeout(Duration::from_secs(4), accept_task)
+        .await
+        .unwrap()
+        .unwrap()
+}
+
+#[tokio::test]
+async fn diagnostic_timing_profiles_are_within_realistic_guardrails() {
+    let classes = [17usize, 511usize, 1023usize, 4095usize];
+    for class in classes {
+        let mut samples = Vec::new();
+        for _ in 0..8 {
+            samples.push(measure_reject_duration_ms(class).await);
+        }
+
+        let p50 = percentile_ms(samples.clone(), 50, 100);
+        let p95 = percentile_ms(samples.clone(), 95, 100);
+        let max = *samples.iter().max().unwrap();
+        println!(
+            "diagnostic_timing class={} p50={}ms p95={}ms max={}ms",
+            class, p50, p95, max
+        );
+
+        assert!(p50 >= 650, "p50 too low for delayed reject class={}", class);
+        assert!(
+            p95 <= 1200,
+            "p95 too high for delayed reject class={}",
+            class
+        );
+        assert!(
+            max <= 1500,
+            "max too high for delayed reject class={}",
+            class
+        );
+    }
+}
+
+#[tokio::test]
+async fn diagnostic_forwarded_size_profiles_by_probe_class() {
+    let classes = [
+        0usize, 1usize, 7usize, 17usize, 63usize, 511usize, 1023usize, 2047usize,
+    ];
+    let mut observed = Vec::new();
+
+    for class in classes {
+        let len = capture_forwarded_len(class).await;
+        println!("diagnostic_shape class={} forwarded_len={}", class, len);
+        observed.push(len as u128);
+        assert_eq!(
+            len,
+            5 + class,
+            "unexpected forwarded len for class={}",
+            class
+        );
+    }
+
+    let p50 = percentile_ms(observed.clone(), 50, 100);
+    let p95 = percentile_ms(observed.clone(), 95, 100);
+    let max = *observed.iter().max().unwrap();
+    println!(
+        "diagnostic_shape_summary p50={}bytes p95={}bytes max={}bytes",
+        p50, p95, max
+    );
+
+    assert!(p95 >= p50);
+    assert!(max >= p95);
+}

src/proxy/tests/client_masking_fragmented_classifier_security_tests.rs

@@ -0,0 +1,100 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use std::sync::Arc;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+use tokio::time::Duration;
+
+fn new_upstream_manager(stats: Arc<Stats>) -> Arc<UpstreamManager> {
+    Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats,
+    ))
+}
+
+#[tokio::test]
+async fn fragmented_connect_probe_is_classified_as_http_via_prefetch_window() {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = Vec::new();
+        stream.read_to_end(&mut got).await.unwrap();
+        got
+    });
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = true;
+    cfg.general.beobachten_minutes = 1;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.general.modes.classic = false;
+    cfg.general.modes.secure = false;
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+    let beobachten = Arc::new(BeobachtenStore::new());
+
+    let (server_side, mut client_side) = duplex(4096);
+    let peer: SocketAddr = "198.51.100.251:57501".parse().unwrap();
+
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        peer,
+        config,
+        stats.clone(),
+        new_upstream_manager(stats),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        beobachten.clone(),
+        false,
+    ));
+
+    client_side.write_all(b"CONNE").await.unwrap();
+    client_side
+        .write_all(b"CT example.org:443 HTTP/1.1\r\nHost: example.org\r\n\r\n")
+        .await
+        .unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let forwarded = tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(
+        forwarded.starts_with(b"CONNECT example.org:443 HTTP/1.1"),
+        "mask backend must receive the full fragmented CONNECT probe"
+    );
+
+    let result = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+
+    let snapshot = beobachten.snapshot_text(Duration::from_secs(60));
+    assert!(snapshot.contains("[HTTP]"));
+    assert!(snapshot.contains("198.51.100.251-1"));
+}

src/proxy/tests/client_masking_hard_adversarial_tests.rs

@@ -0,0 +1,767 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use crate::crypto::sha256_hmac;
+use crate::protocol::constants::{HANDSHAKE_LEN, TLS_RECORD_APPLICATION, TLS_VERSION};
+use crate::protocol::tls;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+use tokio::time::{Duration, Instant};
+
+struct Harness {
+    config: Arc<ProxyConfig>,
+    stats: Arc<Stats>,
+    upstream_manager: Arc<UpstreamManager>,
+    replay_checker: Arc<ReplayChecker>,
+    buffer_pool: Arc<BufferPool>,
+    rng: Arc<SecureRandom>,
+    route_runtime: Arc<RouteRuntimeController>,
+    ip_tracker: Arc<UserIpTracker>,
+    beobachten: Arc<BeobachtenStore>,
+}
+
+fn new_upstream_manager(stats: Arc<Stats>) -> Arc<UpstreamManager> {
+    Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats,
+    ))
+}
+
+fn build_harness(secret_hex: &str, mask_port: u16) -> Harness {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = mask_port;
+    cfg.censorship.mask_proxy_protocol = 0;
+    cfg.access.ignore_time_skew = true;
+    cfg.access
+        .users
+        .insert("user".to_string(), secret_hex.to_string());
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+
+    Harness {
+        config,
+        stats: stats.clone(),
+        upstream_manager: new_upstream_manager(stats),
+        replay_checker: Arc::new(ReplayChecker::new(512, Duration::from_secs(60))),
+        buffer_pool: Arc::new(BufferPool::new()),
+        rng: Arc::new(SecureRandom::new()),
+        route_runtime: Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        ip_tracker: Arc::new(UserIpTracker::new()),
+        beobachten: Arc::new(BeobachtenStore::new()),
+    }
+}
+
+fn make_valid_tls_client_hello(secret: &[u8], timestamp: u32, tls_len: usize, fill: u8) -> Vec<u8> {
+    assert!(
+        tls_len <= u16::MAX as usize,
+        "TLS length must fit into record header"
+    );
+
+    let total_len = 5 + tls_len;
+    let mut handshake = vec![fill; total_len];
+
+    handshake[0] = 0x16;
+    handshake[1] = 0x03;
+    handshake[2] = 0x01;
+    handshake[3..5].copy_from_slice(&(tls_len as u16).to_be_bytes());
+
+    let session_id_len: usize = 32;
+    handshake[tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN] = session_id_len as u8;
+
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN].fill(0);
+    let computed = sha256_hmac(secret, &handshake);
+    let mut digest = computed;
+    let ts = timestamp.to_le_bytes();
+    for i in 0..4 {
+        digest[28 + i] ^= ts[i];
+    }
+
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN]
+        .copy_from_slice(&digest);
+    handshake
+}
+
+fn wrap_tls_application_data(payload: &[u8]) -> Vec<u8> {
+    let mut record = Vec::with_capacity(5 + payload.len());
+    record.push(TLS_RECORD_APPLICATION);
+    record.extend_from_slice(&TLS_VERSION);
+    record.extend_from_slice(&(payload.len() as u16).to_be_bytes());
+    record.extend_from_slice(payload);
+    record
+}
+
+async fn read_tls_record_body<T>(stream: &mut T, header: [u8; 5])
+where
+    T: tokio::io::AsyncRead + Unpin,
+{
+    let len = u16::from_be_bytes([header[3], header[4]]) as usize;
+    let mut body = vec![0u8; len];
+    stream.read_exact(&mut body).await.unwrap();
+}
+
+async fn run_tls_success_mtproto_fail_capture(
+    secret_hex: &str,
+    secret: [u8; 16],
+    timestamp: u32,
+    trailing_records: Vec<Vec<u8>>,
+) -> Vec<u8> {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let expected_len = trailing_records.iter().map(Vec::len).sum::<usize>();
+    let expected_concat = trailing_records.concat();
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = vec![0u8; expected_len];
+        stream.read_exact(&mut got).await.unwrap();
+        got
+    });
+
+    let harness = build_harness(secret_hex, backend_addr.port());
+    let client_hello = make_valid_tls_client_hello(&secret, timestamp, 600, 0x42);
+    let invalid_mtproto_record = wrap_tls_application_data(&vec![0u8; HANDSHAKE_LEN]);
+
+    let (server_side, mut client_side) = duplex(262144);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.210:56010".parse().unwrap(),
+        harness.config,
+        harness.stats,
+        harness.upstream_manager,
+        harness.replay_checker,
+        harness.buffer_pool,
+        harness.rng,
+        None,
+        harness.route_runtime,
+        None,
+        harness.ip_tracker,
+        harness.beobachten,
+        false,
+    ));
+
+    client_side.write_all(&client_hello).await.unwrap();
+
+    let mut tls_response_head = [0u8; 5];
+    client_side
+        .read_exact(&mut tls_response_head)
+        .await
+        .unwrap();
+    assert_eq!(tls_response_head[0], 0x16);
+    read_tls_record_body(&mut client_side, tls_response_head).await;
+
+    client_side
+        .write_all(&invalid_mtproto_record)
+        .await
+        .unwrap();
+    for record in trailing_records {
+        client_side.write_all(&record).await.unwrap();
+    }
+
+    let got = tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(got, expected_concat);
+
+    drop(client_side);
+    let _ = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    got
+}
+
+#[tokio::test]
+async fn masking_budget_survives_zero_handshake_timeout_with_delay() {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.timeouts.client_handshake = 0;
+    cfg.censorship.server_hello_delay_min_ms = 720;
+    cfg.censorship.server_hello_delay_max_ms = 720;
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = vec![0u8; 605];
+        stream.read_exact(&mut got).await.unwrap();
+        got
+    });
+
+    let (server_side, mut client_side) = duplex(65536);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.211:56011".parse().unwrap(),
+        config,
+        stats.clone(),
+        new_upstream_manager(stats.clone()),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let mut invalid_hello = vec![0u8; 605];
+    invalid_hello[0] = 0x16;
+    invalid_hello[1] = 0x03;
+    invalid_hello[2] = 0x01;
+    invalid_hello[3..5].copy_from_slice(&600u16.to_be_bytes());
+    invalid_hello[5..].fill(0xA1);
+
+    let started = Instant::now();
+    client_side.write_all(&invalid_hello).await.unwrap();
+
+    let _ = tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+
+    client_side.shutdown().await.unwrap();
+    let result = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    assert!(result.is_ok());
+    assert_eq!(stats.get_handshake_timeouts(), 0);
+    assert!(started.elapsed() >= Duration::from_millis(680));
+}
+
+#[tokio::test]
+async fn tls_mtproto_fail_forwards_only_trailing_record() {
+    let tail = wrap_tls_application_data(b"tail-only");
+    let got = run_tls_success_mtproto_fail_capture(
+        "c1c1c1c1c1c1c1c1c1c1c1c1c1c1c1c1",
+        [0xC1; 16],
+        1,
+        vec![tail.clone()],
+    )
+    .await;
+    assert_eq!(got, tail);
+}
+
+#[tokio::test]
+async fn replayed_tls_hello_gets_no_serverhello_and_is_masked() {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let harness = build_harness("c2c2c2c2c2c2c2c2c2c2c2c2c2c2c2c2", backend_addr.port());
+    let secret = [0xC2u8; 16];
+    let hello = make_valid_tls_client_hello(&secret, 2, 600, 0x41);
+    let invalid_mtproto_record = wrap_tls_application_data(&vec![0u8; HANDSHAKE_LEN]);
+    let first_tail = wrap_tls_application_data(b"seed");
+
+    let expected_hello = hello.clone();
+    let expected_tail = first_tail.clone();
+
+    let accept_task = tokio::spawn(async move {
+        let (mut s1, _) = listener.accept().await.unwrap();
+        let mut got_tail = vec![0u8; expected_tail.len()];
+        s1.read_exact(&mut got_tail).await.unwrap();
+        assert_eq!(got_tail, expected_tail);
+        drop(s1);
+
+        let (mut s2, _) = listener.accept().await.unwrap();
+        let mut got_hello = vec![0u8; expected_hello.len()];
+        s2.read_exact(&mut got_hello).await.unwrap();
+        assert_eq!(got_hello, expected_hello);
+    });
+
+    let run_session = |send_mtproto: bool| {
+        let (server_side, mut client_side) = duplex(131072);
+        let config = harness.config.clone();
+        let stats = harness.stats.clone();
+        let upstream = harness.upstream_manager.clone();
+        let replay = harness.replay_checker.clone();
+        let pool = harness.buffer_pool.clone();
+        let rng = harness.rng.clone();
+        let route = harness.route_runtime.clone();
+        let ipt = harness.ip_tracker.clone();
+        let beob = harness.beobachten.clone();
+        let hello = hello.clone();
+        let invalid_mtproto_record = invalid_mtproto_record.clone();
+        let first_tail = first_tail.clone();
+
+        async move {
+            let handler = tokio::spawn(handle_client_stream(
+                server_side,
+                "198.51.100.212:56012".parse().unwrap(),
+                config,
+                stats,
+                upstream,
+                replay,
+                pool,
+                rng,
+                None,
+                route,
+                None,
+                ipt,
+                beob,
+                false,
+            ));
+
+            client_side.write_all(&hello).await.unwrap();
+            if send_mtproto {
+                let mut head = [0u8; 5];
+                client_side.read_exact(&mut head).await.unwrap();
+                assert_eq!(head[0], 0x16);
+                read_tls_record_body(&mut client_side, head).await;
+                client_side
+                    .write_all(&invalid_mtproto_record)
+                    .await
+                    .unwrap();
+                client_side.write_all(&first_tail).await.unwrap();
+            } else {
+                let mut one = [0u8; 1];
+                let no_server_hello = tokio::time::timeout(
+                    Duration::from_millis(300),
+                    client_side.read_exact(&mut one),
+                )
+                .await;
+                assert!(no_server_hello.is_err() || no_server_hello.unwrap().is_err());
+            }
+
+            client_side.shutdown().await.unwrap();
+            let _ = tokio::time::timeout(Duration::from_secs(3), handler)
+                .await
+                .unwrap()
+                .unwrap();
+        }
+    };
+
+    run_session(true).await;
+    run_session(false).await;
+
+    tokio::time::timeout(Duration::from_secs(5), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+}
+
+#[tokio::test]
+async fn connects_bad_increments_once_per_invalid_mtproto() {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let harness = build_harness("c3c3c3c3c3c3c3c3c3c3c3c3c3c3c3c3", backend_addr.port());
+    let stats = harness.stats.clone();
+    let bad_before = stats.get_connects_bad();
+
+    let tail = wrap_tls_application_data(b"accounting");
+    let expected_tail = tail.clone();
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = vec![0u8; expected_tail.len()];
+        stream.read_exact(&mut got).await.unwrap();
+        assert_eq!(got, expected_tail);
+    });
+
+    let hello = make_valid_tls_client_hello(&[0xC3; 16], 3, 600, 0x42);
+    let invalid_mtproto_record = wrap_tls_application_data(&vec![0u8; HANDSHAKE_LEN]);
+
+    let (server_side, mut client_side) = duplex(131072);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.213:56013".parse().unwrap(),
+        harness.config,
+        harness.stats,
+        harness.upstream_manager,
+        harness.replay_checker,
+        harness.buffer_pool,
+        harness.rng,
+        None,
+        harness.route_runtime,
+        None,
+        harness.ip_tracker,
+        harness.beobachten,
+        false,
+    ));
+
+    client_side.write_all(&hello).await.unwrap();
+    let mut head = [0u8; 5];
+    client_side.read_exact(&mut head).await.unwrap();
+    read_tls_record_body(&mut client_side, head).await;
+    client_side
+        .write_all(&invalid_mtproto_record)
+        .await
+        .unwrap();
+    client_side.write_all(&tail).await.unwrap();
+
+    tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+
+    client_side.shutdown().await.unwrap();
+    let _ = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    assert_eq!(stats.get_connects_bad(), bad_before + 1);
+}
+
+#[tokio::test]
+async fn truncated_clienthello_forwards_only_seen_prefix() {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.censorship.mask_unix_sock = None;
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+
+    let expected_prefix_len = 5 + 17;
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = vec![0u8; expected_prefix_len];
+        stream.read_exact(&mut got).await.unwrap();
+        got
+    });
+
+    let (server_side, mut client_side) = duplex(65536);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.214:56014".parse().unwrap(),
+        config,
+        stats,
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let mut hello = vec![0u8; 5 + 17];
+    hello[0] = 0x16;
+    hello[1] = 0x03;
+    hello[2] = 0x01;
+    hello[3..5].copy_from_slice(&600u16.to_be_bytes());
+    hello[5..].fill(0x55);
+
+    client_side.write_all(&hello).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let got = tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(got, hello);
+
+    let _ = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+}
+
+#[tokio::test]
+async fn out_of_bounds_tls_len_forwards_header_only() {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.censorship.mask_unix_sock = None;
+
+    let config = Arc::new(cfg);
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = [0u8; 5];
+        stream.read_exact(&mut got).await.unwrap();
+        got
+    });
+
+    let (server_side, mut client_side) = duplex(8192);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.215:56015".parse().unwrap(),
+        config,
+        Arc::new(Stats::new()),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let hdr = [0x16, 0x03, 0x01, 0x42, 0x69];
+    client_side.write_all(&hdr).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let got = tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(got, hdr);
+
+    let _ = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+}
+
+#[tokio::test]
+async fn non_tls_with_modes_disabled_is_masked() {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.censorship.mask_unix_sock = None;
+    cfg.general.modes.classic = false;
+    cfg.general.modes.secure = false;
+
+    let config = Arc::new(cfg);
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = [0u8; 5];
+        stream.read_exact(&mut got).await.unwrap();
+        got
+    });
+
+    let (server_side, mut client_side) = duplex(8192);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.216:56016".parse().unwrap(),
+        config,
+        Arc::new(Stats::new()),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let probe = *b"HELLO";
+    client_side.write_all(&probe).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let got = tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(got, probe);
+
+    let _ = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+}
+
+#[tokio::test]
+async fn concurrent_tls_mtproto_fail_sessions_are_isolated() {
+    let sessions = 12usize;
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut expected = std::collections::HashSet::new();
+    for idx in 0..sessions {
+        let payload = vec![idx as u8; 32 + idx];
+        expected.insert(wrap_tls_application_data(&payload));
+    }
+
+    let accept_task = tokio::spawn(async move {
+        let mut remaining = expected;
+        for _ in 0..sessions {
+            let (mut stream, _) = listener.accept().await.unwrap();
+            let mut header = [0u8; 5];
+            stream.read_exact(&mut header).await.unwrap();
+            assert_eq!(header[0], TLS_RECORD_APPLICATION);
+            let len = u16::from_be_bytes([header[3], header[4]]) as usize;
+            let mut record = vec![0u8; 5 + len];
+            record[..5].copy_from_slice(&header);
+            stream.read_exact(&mut record[5..]).await.unwrap();
+            assert!(remaining.remove(&record));
+        }
+        assert!(remaining.is_empty());
+    });
+
+    let mut tasks = Vec::with_capacity(sessions);
+    for idx in 0..sessions {
+        let secret_hex = "c4c4c4c4c4c4c4c4c4c4c4c4c4c4c4c4";
+        let harness = build_harness(secret_hex, backend_addr.port());
+        let hello =
+            make_valid_tls_client_hello(&[0xC4; 16], 20 + idx as u32, 600, 0x40 + idx as u8);
+        let invalid_mtproto = wrap_tls_application_data(&vec![0u8; HANDSHAKE_LEN]);
+        let trailing = wrap_tls_application_data(&vec![idx as u8; 32 + idx]);
+        let peer: SocketAddr = format!("198.51.100.217:{}", 56100 + idx as u16)
+            .parse()
+            .unwrap();
+
+        tasks.push(tokio::spawn(async move {
+            let (server_side, mut client_side) = duplex(131072);
+            let handler = tokio::spawn(handle_client_stream(
+                server_side,
+                peer,
+                harness.config,
+                harness.stats,
+                harness.upstream_manager,
+                harness.replay_checker,
+                harness.buffer_pool,
+                harness.rng,
+                None,
+                harness.route_runtime,
+                None,
+                harness.ip_tracker,
+                harness.beobachten,
+                false,
+            ));
+
+            client_side.write_all(&hello).await.unwrap();
+            let mut head = [0u8; 5];
+            client_side.read_exact(&mut head).await.unwrap();
+            read_tls_record_body(&mut client_side, head).await;
+            client_side.write_all(&invalid_mtproto).await.unwrap();
+            client_side.write_all(&trailing).await.unwrap();
+            client_side.shutdown().await.unwrap();
+
+            let _ = tokio::time::timeout(Duration::from_secs(3), handler)
+                .await
+                .unwrap()
+                .unwrap();
+        }));
+    }
+
+    for task in tasks {
+        task.await.unwrap();
+    }
+
+    tokio::time::timeout(Duration::from_secs(6), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+}
+
+macro_rules! tail_length_case {
+    ($name:ident, $hex:expr, $secret:expr, $ts:expr, $len:expr) => {
+        #[tokio::test]
+        async fn $name() {
+            let mut payload = vec![0u8; $len];
+            for (i, b) in payload.iter_mut().enumerate() {
+                *b = (i as u8).wrapping_mul(17).wrapping_add(5);
+            }
+            let record = wrap_tls_application_data(&payload);
+            let got =
+                run_tls_success_mtproto_fail_capture($hex, $secret, $ts, vec![record.clone()])
+                    .await;
+            assert_eq!(got, record);
+        }
+    };
+}
+
+tail_length_case!(
+    tail_len_1_preserved,
+    "d1d1d1d1d1d1d1d1d1d1d1d1d1d1d1d1",
+    [0xD1; 16],
+    30,
+    1
+);
+tail_length_case!(
+    tail_len_2_preserved,
+    "d2d2d2d2d2d2d2d2d2d2d2d2d2d2d2d2",
+    [0xD2; 16],
+    31,
+    2
+);
+tail_length_case!(
+    tail_len_3_preserved,
+    "d3d3d3d3d3d3d3d3d3d3d3d3d3d3d3d3",
+    [0xD3; 16],
+    32,
+    3
+);
+tail_length_case!(
+    tail_len_7_preserved,
+    "d4d4d4d4d4d4d4d4d4d4d4d4d4d4d4d4",
+    [0xD4; 16],
+    33,
+    7
+);
+tail_length_case!(
+    tail_len_31_preserved,
+    "d5d5d5d5d5d5d5d5d5d5d5d5d5d5d5d5",
+    [0xD5; 16],
+    34,
+    31
+);
+tail_length_case!(
+    tail_len_127_preserved,
+    "d6d6d6d6d6d6d6d6d6d6d6d6d6d6d6d6",
+    [0xD6; 16],
+    35,
+    127
+);
+tail_length_case!(
+    tail_len_511_preserved,
+    "d7d7d7d7d7d7d7d7d7d7d7d7d7d7d7d7",
+    [0xD7; 16],
+    36,
+    511
+);
+tail_length_case!(
+    tail_len_1023_preserved,
+    "d8d8d8d8d8d8d8d8d8d8d8d8d8d8d8d8",
+    [0xD8; 16],
+    37,
+    1023
+);

src/proxy/tests/client_masking_http2_fragmented_preface_security_tests.rs

@@ -0,0 +1,122 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use std::sync::Arc;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+use tokio::time::{Duration, sleep};
+
+fn new_upstream_manager(stats: Arc<Stats>) -> Arc<UpstreamManager> {
+    Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats,
+    ))
+}
+
+async fn run_http2_fragment_case(split_at: usize, delay_ms: u64, peer: SocketAddr) {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+    let preface = b"PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n".to_vec();
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = Vec::new();
+        stream.read_to_end(&mut got).await.unwrap();
+        got
+    });
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = true;
+    cfg.general.beobachten_minutes = 1;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.general.modes.classic = false;
+    cfg.general.modes.secure = false;
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+    let beobachten = Arc::new(BeobachtenStore::new());
+
+    let (server_side, mut client_side) = duplex(4096);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        peer,
+        config,
+        stats.clone(),
+        new_upstream_manager(stats),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        beobachten.clone(),
+        false,
+    ));
+
+    let first = split_at.min(preface.len());
+    client_side.write_all(&preface[..first]).await.unwrap();
+    if first < preface.len() {
+        sleep(Duration::from_millis(delay_ms)).await;
+        client_side.write_all(&preface[first..]).await.unwrap();
+    }
+    client_side.shutdown().await.unwrap();
+
+    let forwarded = tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(
+        forwarded.starts_with(&preface),
+        "mask backend must receive an intact HTTP/2 preface prefix"
+    );
+
+    let result = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+
+    let snapshot = beobachten.snapshot_text(Duration::from_secs(60));
+    assert!(snapshot.contains("[HTTP]"));
+    assert!(snapshot.contains(&format!("{}-1", peer.ip())));
+}
+
+#[tokio::test]
+async fn http2_preface_fragmentation_matrix_is_classified_and_forwarded() {
+    let cases = [(2usize, 0u64), (3, 0), (4, 0), (2, 7), (3, 7), (8, 1)];
+
+    for (i, (split_at, delay_ms)) in cases.into_iter().enumerate() {
+        let peer: SocketAddr = format!("198.51.100.{}:58{}", 140 + i, 100 + i)
+            .parse()
+            .unwrap();
+        run_http2_fragment_case(split_at, delay_ms, peer).await;
+    }
+}
+
+#[tokio::test]
+async fn http2_preface_splitpoint_light_fuzz_classifies_http() {
+    for split_at in 2usize..=12 {
+        let delay_ms = if split_at % 3 == 0 { 7 } else { 1 };
+        let peer: SocketAddr = format!("198.51.101.{}:59{}", split_at, 10 + split_at)
+            .parse()
+            .unwrap();
+        run_http2_fragment_case(split_at, delay_ms, peer).await;
+    }
+}

src/proxy/tests/client_masking_prefetch_config_pipeline_integration_security_tests.rs

@@ -0,0 +1,150 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use std::sync::Arc;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+use tokio::time::{Duration, sleep};
+
+fn new_upstream_manager(stats: Arc<Stats>) -> Arc<UpstreamManager> {
+    Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats,
+    ))
+}
+
+async fn run_pipeline_prefetch_case(
+    prefetch_timeout_ms: u64,
+    delayed_tail_ms: u64,
+    peer: SocketAddr,
+) -> (Vec<u8>, String) {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = Vec::new();
+        stream.read_to_end(&mut got).await.unwrap();
+        got
+    });
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = true;
+    cfg.general.beobachten_minutes = 1;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.censorship.mask_classifier_prefetch_timeout_ms = prefetch_timeout_ms;
+    cfg.general.modes.classic = false;
+    cfg.general.modes.secure = false;
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+    let beobachten = Arc::new(BeobachtenStore::new());
+
+    let (server_side, mut client_side) = duplex(4096);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        peer,
+        config,
+        stats.clone(),
+        new_upstream_manager(stats),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        beobachten.clone(),
+        false,
+    ));
+
+    client_side.write_all(b"C").await.unwrap();
+    sleep(Duration::from_millis(delayed_tail_ms)).await;
+
+    client_side
+        .write_all(b"ONNECT example.org:443 HTTP/1.1\r\nHost: example.org\r\n\r\n")
+        .await
+        .unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let forwarded = tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+
+    let result = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+
+    let snapshot = beobachten.snapshot_text(Duration::from_secs(60));
+    (forwarded, snapshot)
+}
+
+#[tokio::test]
+async fn tdd_pipeline_prefetch_5ms_misses_15ms_tail_and_classifies_as_port_scanner() {
+    let peer: SocketAddr = "198.51.100.171:58071".parse().unwrap();
+    let (forwarded, snapshot) = run_pipeline_prefetch_case(5, 15, peer).await;
+
+    assert!(
+        forwarded.starts_with(b"CONNECT"),
+        "mask backend must still receive full payload bytes in-order"
+    );
+    assert!(
+        snapshot.contains("[HTTP]") || snapshot.contains("[port-scanner]"),
+        "unexpected classifier snapshot for 5ms delayed-tail case: {snapshot}"
+    );
+}
+
+#[tokio::test]
+async fn tdd_pipeline_prefetch_20ms_recovers_15ms_tail_and_classifies_as_http() {
+    let peer: SocketAddr = "198.51.100.172:58072".parse().unwrap();
+    let (forwarded, snapshot) = run_pipeline_prefetch_case(20, 15, peer).await;
+
+    assert!(
+        forwarded.starts_with(b"CONNECT"),
+        "mask backend must receive full CONNECT payload"
+    );
+    assert!(
+        snapshot.contains("[HTTP]"),
+        "20ms budget should recover delayed fragmented prefix and classify as HTTP"
+    );
+}
+
+#[tokio::test]
+async fn matrix_pipeline_prefetch_budget_behavior_5_20_50ms() {
+    let peer5: SocketAddr = "198.51.100.173:58073".parse().unwrap();
+    let peer20: SocketAddr = "198.51.100.174:58074".parse().unwrap();
+    let peer50: SocketAddr = "198.51.100.175:58075".parse().unwrap();
+
+    let (_, snap5) = run_pipeline_prefetch_case(5, 35, peer5).await;
+    let (_, snap20) = run_pipeline_prefetch_case(20, 35, peer20).await;
+    let (_, snap50) = run_pipeline_prefetch_case(50, 35, peer50).await;
+
+    assert!(
+        snap5.contains("[HTTP]") || snap5.contains("[port-scanner]"),
+        "unexpected 5ms snapshot: {snap5}"
+    );
+    assert!(
+        snap20.contains("[HTTP]") || snap20.contains("[port-scanner]"),
+        "unexpected 20ms snapshot: {snap20}"
+    );
+    assert!(snap50.contains("[HTTP]"));
+}

src/proxy/tests/client_masking_prefetch_config_runtime_security_tests.rs

@@ -0,0 +1,88 @@
+use super::*;
+use tokio::io::{AsyncWriteExt, duplex};
+use tokio::time::{Duration, sleep};
+
+#[test]
+fn prefetch_timeout_budget_reads_from_config() {
+    let mut cfg = ProxyConfig::default();
+    assert_eq!(
+        mask_classifier_prefetch_timeout(&cfg),
+        Duration::from_millis(5),
+        "default prefetch timeout budget must remain 5ms"
+    );
+
+    cfg.censorship.mask_classifier_prefetch_timeout_ms = 20;
+    assert_eq!(
+        mask_classifier_prefetch_timeout(&cfg),
+        Duration::from_millis(20),
+        "runtime prefetch timeout budget must follow configured value"
+    );
+}
+
+#[tokio::test]
+async fn configured_prefetch_budget_20ms_recovers_tail_delayed_15ms() {
+    let (mut reader, mut writer) = duplex(1024);
+
+    let writer_task = tokio::spawn(async move {
+        sleep(Duration::from_millis(15)).await;
+        writer
+            .write_all(b"ONNECT example.org:443 HTTP/1.1\r\n")
+            .await
+            .expect("tail bytes must be writable");
+        writer
+            .shutdown()
+            .await
+            .expect("writer shutdown must succeed");
+    });
+
+    let mut initial_data = b"C".to_vec();
+    extend_masking_initial_window_with_timeout(
+        &mut reader,
+        &mut initial_data,
+        Duration::from_millis(20),
+    )
+    .await;
+
+    writer_task
+        .await
+        .expect("writer task must not panic in runtime timeout test");
+
+    assert!(
+        initial_data.starts_with(b"CONNECT"),
+        "20ms configured prefetch budget should recover 15ms delayed CONNECT tail"
+    );
+}
+
+#[tokio::test]
+async fn configured_prefetch_budget_5ms_misses_tail_delayed_15ms() {
+    let (mut reader, mut writer) = duplex(1024);
+
+    let writer_task = tokio::spawn(async move {
+        sleep(Duration::from_millis(15)).await;
+        writer
+            .write_all(b"ONNECT example.org:443 HTTP/1.1\r\n")
+            .await
+            .expect("tail bytes must be writable");
+        writer
+            .shutdown()
+            .await
+            .expect("writer shutdown must succeed");
+    });
+
+    let mut initial_data = b"C".to_vec();
+    extend_masking_initial_window_with_timeout(
+        &mut reader,
+        &mut initial_data,
+        Duration::from_millis(5),
+    )
+    .await;
+
+    writer_task
+        .await
+        .expect("writer task must not panic in runtime timeout test");
+
+    assert!(
+        !initial_data.starts_with(b"CONNECT"),
+        "5ms configured prefetch budget should miss 15ms delayed CONNECT tail"
+    );
+}

src/proxy/tests/client_masking_prefetch_invariant_security_tests.rs

@@ -0,0 +1,264 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use crate::crypto::sha256_hmac;
+use crate::protocol::constants::{HANDSHAKE_LEN, TLS_VERSION};
+use crate::protocol::tls;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+
+struct PipelineHarness {
+    config: Arc<ProxyConfig>,
+    stats: Arc<Stats>,
+    upstream_manager: Arc<UpstreamManager>,
+    replay_checker: Arc<ReplayChecker>,
+    buffer_pool: Arc<BufferPool>,
+    rng: Arc<SecureRandom>,
+    route_runtime: Arc<RouteRuntimeController>,
+    ip_tracker: Arc<UserIpTracker>,
+    beobachten: Arc<BeobachtenStore>,
+}
+
+fn build_harness(secret_hex: &str, mask_port: u16) -> PipelineHarness {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = mask_port;
+    cfg.censorship.mask_proxy_protocol = 0;
+    cfg.access.ignore_time_skew = true;
+    cfg.access
+        .users
+        .insert("user".to_string(), secret_hex.to_string());
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+    let upstream_manager = Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats.clone(),
+    ));
+
+    PipelineHarness {
+        config,
+        stats,
+        upstream_manager,
+        replay_checker: Arc::new(ReplayChecker::new(256, Duration::from_secs(60))),
+        buffer_pool: Arc::new(BufferPool::new()),
+        rng: Arc::new(SecureRandom::new()),
+        route_runtime: Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        ip_tracker: Arc::new(UserIpTracker::new()),
+        beobachten: Arc::new(BeobachtenStore::new()),
+    }
+}
+
+fn make_valid_tls_client_hello(secret: &[u8], timestamp: u32, tls_len: usize, fill: u8) -> Vec<u8> {
+    let total_len = 5 + tls_len;
+    let mut handshake = vec![fill; total_len];
+
+    handshake[0] = 0x16;
+    handshake[1] = 0x03;
+    handshake[2] = 0x01;
+    handshake[3..5].copy_from_slice(&(tls_len as u16).to_be_bytes());
+
+    let session_id_len: usize = 32;
+    handshake[tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN] = session_id_len as u8;
+
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN].fill(0);
+    let computed = sha256_hmac(secret, &handshake);
+    let mut digest = computed;
+    let ts = timestamp.to_le_bytes();
+    for i in 0..4 {
+        digest[28 + i] ^= ts[i];
+    }
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN]
+        .copy_from_slice(&digest);
+
+    handshake
+}
+
+fn wrap_tls_application_data(payload: &[u8]) -> Vec<u8> {
+    let mut record = Vec::with_capacity(5 + payload.len());
+    record.push(0x17);
+    record.extend_from_slice(&TLS_VERSION);
+    record.extend_from_slice(&(payload.len() as u16).to_be_bytes());
+    record.extend_from_slice(payload);
+    record
+}
+
+async fn read_and_discard_tls_record_body<T>(stream: &mut T, header: [u8; 5])
+where
+    T: tokio::io::AsyncRead + Unpin,
+{
+    let len = u16::from_be_bytes([header[3], header[4]]) as usize;
+    let mut body = vec![0u8; len];
+    stream.read_exact(&mut body).await.unwrap();
+}
+
+#[test]
+fn empty_initial_data_prefetch_gate_is_fail_closed() {
+    assert!(
+        !should_prefetch_mask_classifier_window(&[]),
+        "empty initial_data must not trigger classifier prefetch"
+    );
+}
+
+#[tokio::test]
+async fn blackhat_empty_initial_data_prefetch_must_not_consume_fallback_payload() {
+    let payload = b"\x17\x03\x03\x00\x10coalesced-tail-bytes".to_vec();
+    let (mut reader, mut writer) = duplex(1024);
+
+    writer.write_all(&payload).await.unwrap();
+    writer.shutdown().await.unwrap();
+
+    let mut initial_data = Vec::new();
+    extend_masking_initial_window(&mut reader, &mut initial_data).await;
+
+    assert!(
+        initial_data.is_empty(),
+        "empty initial_data must remain empty after prefetch stage"
+    );
+
+    let mut remaining = Vec::new();
+    reader.read_to_end(&mut remaining).await.unwrap();
+    assert_eq!(
+        remaining, payload,
+        "prefetch stage must not consume fallback payload when initial_data is empty"
+    );
+}
+
+#[tokio::test]
+async fn positive_fragmented_http_prefix_still_prefetches_within_window() {
+    let (mut reader, mut writer) = duplex(1024);
+    writer
+        .write_all(b"NECT example.org:443 HTTP/1.1\r\n")
+        .await
+        .unwrap();
+    writer.shutdown().await.unwrap();
+
+    let mut initial_data = b"CON".to_vec();
+    extend_masking_initial_window(&mut reader, &mut initial_data).await;
+
+    assert!(
+        initial_data.starts_with(b"CONNECT"),
+        "fragmented HTTP method prefix should still be recoverable by prefetch"
+    );
+    assert!(
+        initial_data.len() <= 16,
+        "prefetch window must remain bounded"
+    );
+}
+
+#[tokio::test]
+async fn light_fuzz_empty_initial_data_never_prefetches_any_bytes() {
+    let mut seed = 0xD15C_A11E_2026_0322u64;
+
+    for _ in 0..128 {
+        seed ^= seed << 7;
+        seed ^= seed >> 9;
+        seed ^= seed << 8;
+
+        let len = ((seed & 0x3f) as usize).saturating_add(1);
+        let mut payload = vec![0u8; len];
+        for (idx, byte) in payload.iter_mut().enumerate() {
+            *byte = (seed as u8).wrapping_add(idx as u8).wrapping_mul(17);
+        }
+
+        let (mut reader, mut writer) = duplex(1024);
+        writer.write_all(&payload).await.unwrap();
+        writer.shutdown().await.unwrap();
+
+        let mut initial_data = Vec::new();
+        extend_masking_initial_window(&mut reader, &mut initial_data).await;
+        assert!(initial_data.is_empty());
+
+        let mut remaining = Vec::new();
+        reader.read_to_end(&mut remaining).await.unwrap();
+        assert_eq!(remaining, payload);
+    }
+}
+
+#[tokio::test]
+async fn blackhat_integration_empty_initial_data_path_is_byte_exact_and_eof_clean() {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let secret = [0xD3u8; 16];
+    let client_hello = make_valid_tls_client_hello(&secret, 411, 600, 0x2B);
+    let mut invalid_payload = vec![0u8; HANDSHAKE_LEN];
+    invalid_payload[0] = 0xFF;
+    let invalid_mtproto_record = wrap_tls_application_data(&invalid_payload);
+    let trailing_record = wrap_tls_application_data(b"empty-prefetch-invariant");
+    let expected = trailing_record.clone();
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+
+        let mut got = vec![0u8; expected.len()];
+        stream.read_exact(&mut got).await.unwrap();
+        assert_eq!(got, expected);
+
+        let mut one = [0u8; 1];
+        let n = stream.read(&mut one).await.unwrap();
+        assert_eq!(
+            n, 0,
+            "fallback stream must not append synthetic bytes on empty initial_data path"
+        );
+    });
+
+    let harness = build_harness("d3d3d3d3d3d3d3d3d3d3d3d3d3d3d3d3", backend_addr.port());
+    let (server_side, mut client_side) = duplex(131072);
+
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.245:56145".parse().unwrap(),
+        harness.config,
+        harness.stats,
+        harness.upstream_manager,
+        harness.replay_checker,
+        harness.buffer_pool,
+        harness.rng,
+        None,
+        harness.route_runtime,
+        None,
+        harness.ip_tracker,
+        harness.beobachten,
+        false,
+    ));
+
+    client_side.write_all(&client_hello).await.unwrap();
+    let mut head = [0u8; 5];
+    client_side.read_exact(&mut head).await.unwrap();
+    assert_eq!(head[0], 0x16);
+    read_and_discard_tls_record_body(&mut client_side, head).await;
+
+    client_side
+        .write_all(&invalid_mtproto_record)
+        .await
+        .unwrap();
+    client_side.write_all(&trailing_record).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+
+    let _ = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+}

src/proxy/tests/client_masking_prefetch_strict_boundary_security_tests.rs

@@ -0,0 +1,72 @@
+use super::*;
+use tokio::io::{AsyncWriteExt, duplex};
+use tokio::time::{Duration, advance, sleep};
+
+async fn run_strict_prefetch_case(prefetch_ms: u64, tail_delay_ms: u64) -> Vec<u8> {
+    let (mut reader, mut writer) = duplex(1024);
+
+    let writer_task = tokio::spawn(async move {
+        sleep(Duration::from_millis(tail_delay_ms)).await;
+        let _ = writer
+            .write_all(b"ONNECT example.org:443 HTTP/1.1\r\n")
+            .await;
+        let _ = writer.shutdown().await;
+    });
+
+    let mut initial_data = b"C".to_vec();
+    let mut prefetch_task = tokio::spawn(async move {
+        extend_masking_initial_window_with_timeout(
+            &mut reader,
+            &mut initial_data,
+            Duration::from_millis(prefetch_ms),
+        )
+        .await;
+        initial_data
+    });
+
+    tokio::task::yield_now().await;
+
+    if tail_delay_ms > 0 {
+        advance(Duration::from_millis(tail_delay_ms)).await;
+        tokio::task::yield_now().await;
+    }
+
+    if prefetch_ms > tail_delay_ms {
+        advance(Duration::from_millis(prefetch_ms - tail_delay_ms)).await;
+        tokio::task::yield_now().await;
+    }
+
+    let result = prefetch_task.await.expect("prefetch task must not panic");
+    writer_task.await.expect("writer task must not panic");
+    result
+}
+
+#[tokio::test(start_paused = true)]
+async fn strict_prefetch_5ms_misses_15ms_tail() {
+    let got = run_strict_prefetch_case(5, 15).await;
+    assert_eq!(got, b"C".to_vec());
+}
+
+#[tokio::test(start_paused = true)]
+async fn strict_prefetch_20ms_recovers_15ms_tail() {
+    let got = run_strict_prefetch_case(20, 15).await;
+    assert!(got.starts_with(b"CONNECT"));
+}
+
+#[tokio::test(start_paused = true)]
+async fn strict_prefetch_50ms_recovers_35ms_tail() {
+    let got = run_strict_prefetch_case(50, 35).await;
+    assert!(got.starts_with(b"CONNECT"));
+}
+
+#[tokio::test(start_paused = true)]
+async fn strict_prefetch_equal_budget_and_delay_recovers_tail() {
+    let got = run_strict_prefetch_case(20, 20).await;
+    assert!(got.starts_with(b"CONNECT"));
+}
+
+#[tokio::test(start_paused = true)]
+async fn strict_prefetch_one_ms_after_budget_misses_tail() {
+    let got = run_strict_prefetch_case(20, 21).await;
+    assert_eq!(got, b"C".to_vec());
+}

src/proxy/tests/client_masking_prefetch_timing_matrix_security_tests.rs

@@ -0,0 +1,98 @@
+use super::*;
+use tokio::io::{AsyncRead, AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::time::{Duration, sleep, timeout};
+
+async fn extend_masking_initial_window_with_budget<R>(
+    reader: &mut R,
+    initial_data: &mut Vec<u8>,
+    prefetch_timeout: Duration,
+) where
+    R: AsyncRead + Unpin,
+{
+    if !should_prefetch_mask_classifier_window(initial_data) {
+        return;
+    }
+
+    let need = 16usize.saturating_sub(initial_data.len());
+    if need == 0 {
+        return;
+    }
+
+    let mut extra = [0u8; 16];
+    if let Ok(Ok(n)) = timeout(prefetch_timeout, reader.read(&mut extra[..need])).await
+        && n > 0
+    {
+        initial_data.extend_from_slice(&extra[..n]);
+    }
+}
+
+async fn run_prefetch_budget_case(prefetch_budget_ms: u64, delayed_tail_ms: u64) -> bool {
+    let (mut reader, mut writer) = duplex(1024);
+
+    let writer_task = tokio::spawn(async move {
+        sleep(Duration::from_millis(delayed_tail_ms)).await;
+        writer
+            .write_all(b"ONNECT example.org:443 HTTP/1.1\r\n")
+            .await
+            .expect("tail bytes must be writable");
+        writer
+            .shutdown()
+            .await
+            .expect("writer shutdown must succeed");
+    });
+
+    let mut initial_data = b"C".to_vec();
+    extend_masking_initial_window_with_budget(
+        &mut reader,
+        &mut initial_data,
+        Duration::from_millis(prefetch_budget_ms),
+    )
+    .await;
+
+    writer_task
+        .await
+        .expect("writer task must not panic during matrix case");
+
+    initial_data.starts_with(b"CONNECT")
+}
+
+#[tokio::test]
+async fn adversarial_prefetch_budget_matrix_5_20_50ms_for_fragmented_connect_tail() {
+    let cases = [
+        // (tail-delay-ms, expected CONNECT recovery for budgets [5, 20, 50])
+        (2u64, [true, true, true]),
+        (15u64, [false, true, true]),
+        (35u64, [false, false, true]),
+    ];
+
+    for (tail_delay_ms, expected) in cases {
+        let got_5 = run_prefetch_budget_case(5, tail_delay_ms).await;
+        let got_20 = run_prefetch_budget_case(20, tail_delay_ms).await;
+        let got_50 = run_prefetch_budget_case(50, tail_delay_ms).await;
+
+        assert_eq!(
+            got_5, expected[0],
+            "5ms prefetch budget mismatch for tail delay {}ms",
+            tail_delay_ms
+        );
+        assert_eq!(
+            got_20, expected[1],
+            "20ms prefetch budget mismatch for tail delay {}ms",
+            tail_delay_ms
+        );
+        assert_eq!(
+            got_50, expected[2],
+            "50ms prefetch budget mismatch for tail delay {}ms",
+            tail_delay_ms
+        );
+    }
+}
+
+#[tokio::test]
+async fn control_current_runtime_prefetch_budget_is_5ms() {
+    assert_eq!(
+        MASK_CLASSIFIER_PREFETCH_TIMEOUT,
+        Duration::from_millis(5),
+        "matrix assumptions require current runtime prefetch budget to stay at 5ms"
+    );
+}

src/proxy/tests/client_masking_probe_evasion_blackhat_tests.rs

@@ -0,0 +1,358 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use rand::rngs::StdRng;
+use rand::{Rng, SeedableRng};
+use std::net::SocketAddr;
+use std::sync::Arc;
+use std::time::Duration;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::{TcpListener, TcpStream};
+
+const REPLY_404: &[u8] = b"HTTP/1.1 404 Not Found\r\nContent-Length: 0\r\n\r\n";
+
+fn make_test_upstream_manager(stats: Arc<Stats>) -> Arc<UpstreamManager> {
+    Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats,
+    ))
+}
+
+fn masking_config(mask_port: u16) -> Arc<ProxyConfig> {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.timeouts.client_handshake = 1;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = mask_port;
+    cfg.censorship.mask_proxy_protocol = 0;
+    Arc::new(cfg)
+}
+
+async fn run_generic_probe_and_capture_prefix(payload: Vec<u8>, expected_prefix: Vec<u8>) {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let reply = REPLY_404.to_vec();
+    let prefix_len = expected_prefix.len();
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = vec![0u8; prefix_len];
+        stream.read_exact(&mut got).await.unwrap();
+        stream.write_all(&reply).await.unwrap();
+        got
+    });
+
+    let config = masking_config(backend_addr.port());
+    let stats = Arc::new(Stats::new());
+    let upstream_manager = make_test_upstream_manager(stats.clone());
+    let replay_checker = Arc::new(ReplayChecker::new(128, Duration::from_secs(60)));
+    let buffer_pool = Arc::new(BufferPool::new());
+    let rng = Arc::new(SecureRandom::new());
+    let route_runtime = Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct));
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    let beobachten = Arc::new(BeobachtenStore::new());
+
+    let (server_side, mut client_side) = duplex(4096);
+    let peer: SocketAddr = "203.0.113.210:55110".parse().unwrap();
+
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        peer,
+        config,
+        stats,
+        upstream_manager,
+        replay_checker,
+        buffer_pool,
+        rng,
+        None,
+        route_runtime,
+        None,
+        ip_tracker,
+        beobachten,
+        false,
+    ));
+
+    client_side.write_all(&payload).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let mut observed = vec![0u8; REPLY_404.len()];
+    tokio::time::timeout(
+        Duration::from_secs(2),
+        client_side.read_exact(&mut observed),
+    )
+    .await
+    .unwrap()
+    .unwrap();
+    assert_eq!(observed, REPLY_404);
+
+    let got = tokio::time::timeout(Duration::from_secs(2), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(got, expected_prefix);
+
+    let result = tokio::time::timeout(Duration::from_secs(2), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+}
+
+async fn read_http_probe_header(stream: &mut TcpStream) -> Vec<u8> {
+    let mut out = Vec::with_capacity(96);
+    let mut one = [0u8; 1];
+
+    loop {
+        stream.read_exact(&mut one).await.unwrap();
+        out.push(one[0]);
+        if out.ends_with(b"\r\n\r\n") {
+            break;
+        }
+        assert!(
+            out.len() <= 512,
+            "probe header exceeded sane limit while waiting for terminator"
+        );
+    }
+
+    out
+}
+
+#[tokio::test]
+async fn blackhat_fragmented_plain_http_probe_masks_and_preserves_prefix() {
+    let payload = b"GET /probe-evasion HTTP/1.1\r\nHost: front.example\r\n\r\n".to_vec();
+    run_generic_probe_and_capture_prefix(payload.clone(), payload).await;
+}
+
+#[tokio::test]
+async fn blackhat_invalid_tls_like_probe_masks_and_preserves_header_prefix() {
+    let payload = vec![0x16, 0x03, 0x03, 0x00, 0x64, 0x01, 0x00];
+    run_generic_probe_and_capture_prefix(payload.clone(), payload).await;
+}
+
+#[tokio::test]
+async fn integration_client_handler_plain_probe_masks_and_preserves_prefix() {
+    let mask_listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = mask_listener.local_addr().unwrap();
+
+    let front_listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let front_addr = front_listener.local_addr().unwrap();
+
+    let payload = b"GET /integration-probe HTTP/1.1\r\nHost: a.example\r\n\r\n".to_vec();
+    let expected_prefix = payload.clone();
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = mask_listener.accept().await.unwrap();
+        let mut got = vec![0u8; expected_prefix.len()];
+        stream.read_exact(&mut got).await.unwrap();
+        stream.write_all(REPLY_404).await.unwrap();
+        got
+    });
+
+    let config = masking_config(backend_addr.port());
+    let stats = Arc::new(Stats::new());
+    let upstream_manager = make_test_upstream_manager(stats.clone());
+    let replay_checker = Arc::new(ReplayChecker::new(128, Duration::from_secs(60)));
+    let buffer_pool = Arc::new(BufferPool::new());
+    let rng = Arc::new(SecureRandom::new());
+    let route_runtime = Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct));
+    let ip_tracker = Arc::new(UserIpTracker::new());
+    let beobachten = Arc::new(BeobachtenStore::new());
+
+    let server_task = {
+        let config = config.clone();
+        let stats = stats.clone();
+        let upstream_manager = upstream_manager.clone();
+        let replay_checker = replay_checker.clone();
+        let buffer_pool = buffer_pool.clone();
+        let rng = rng.clone();
+        let route_runtime = route_runtime.clone();
+        let ip_tracker = ip_tracker.clone();
+        let beobachten = beobachten.clone();
+
+        tokio::spawn(async move {
+            let (stream, peer) = front_listener.accept().await.unwrap();
+            let real_peer_report = Arc::new(std::sync::Mutex::new(None));
+            ClientHandler::new(
+                stream,
+                peer,
+                config,
+                stats,
+                upstream_manager,
+                replay_checker,
+                buffer_pool,
+                rng,
+                None,
+                route_runtime,
+                None,
+                ip_tracker,
+                beobachten,
+                false,
+                real_peer_report,
+            )
+            .run()
+            .await
+        })
+    };
+
+    let mut client = TcpStream::connect(front_addr).await.unwrap();
+    client.write_all(&payload).await.unwrap();
+    client.shutdown().await.unwrap();
+
+    let mut observed = vec![0u8; REPLY_404.len()];
+    tokio::time::timeout(Duration::from_secs(2), client.read_exact(&mut observed))
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(observed, REPLY_404);
+
+    let got = tokio::time::timeout(Duration::from_secs(2), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(got, payload);
+
+    let result = tokio::time::timeout(Duration::from_secs(2), server_task)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+}
+
+#[tokio::test]
+async fn light_fuzz_small_probe_variants_always_mask_and_preserve_declared_prefix() {
+    let mut rng = StdRng::seed_from_u64(0xA11E_5EED_F0F0_CAFE);
+
+    for i in 0..24usize {
+        let mut payload = if rng.random::<bool>() {
+            b"GET /fuzz HTTP/1.1\r\nHost: fuzz.example\r\n\r\n".to_vec()
+        } else {
+            vec![0x16, 0x03, 0x03, 0x00, 0x64]
+        };
+
+        let tail_len = rng.random_range(0..=8usize);
+        for _ in 0..tail_len {
+            payload.push(rng.random::<u8>());
+        }
+
+        let expected_prefix = payload.clone();
+        run_generic_probe_and_capture_prefix(payload, expected_prefix).await;
+
+        if i % 6 == 0 {
+            tokio::task::yield_now().await;
+        }
+    }
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+async fn stress_parallel_probe_mix_masks_all_sessions_without_cross_leakage() {
+    let session_count = 12usize;
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut expected = std::collections::HashSet::new();
+    for idx in 0..session_count {
+        let probe =
+            format!("GET /stress-{idx} HTTP/1.1\r\nHost: s{idx}.example\r\n\r\n").into_bytes();
+        expected.insert(probe);
+    }
+
+    let accept_task = tokio::spawn(async move {
+        let mut remaining = expected;
+        for _ in 0..session_count {
+            let (mut stream, _) = listener.accept().await.unwrap();
+            let head = read_http_probe_header(&mut stream).await;
+            stream.write_all(REPLY_404).await.unwrap();
+            assert!(
+                remaining.remove(&head),
+                "backend received unexpected or duplicated probe prefix"
+            );
+        }
+        assert!(
+            remaining.is_empty(),
+            "all session prefixes must be observed exactly once"
+        );
+    });
+
+    let mut tasks = Vec::with_capacity(session_count);
+    for idx in 0..session_count {
+        let config = masking_config(backend_addr.port());
+        let stats = Arc::new(Stats::new());
+        let upstream_manager = make_test_upstream_manager(stats.clone());
+        let replay_checker = Arc::new(ReplayChecker::new(128, Duration::from_secs(60)));
+        let buffer_pool = Arc::new(BufferPool::new());
+        let rng = Arc::new(SecureRandom::new());
+        let route_runtime = Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct));
+        let ip_tracker = Arc::new(UserIpTracker::new());
+        let beobachten = Arc::new(BeobachtenStore::new());
+
+        let probe =
+            format!("GET /stress-{idx} HTTP/1.1\r\nHost: s{idx}.example\r\n\r\n").into_bytes();
+        let peer: SocketAddr = format!("203.0.113.{}:{}", 30 + idx, 56000 + idx)
+            .parse()
+            .unwrap();
+
+        tasks.push(tokio::spawn(async move {
+            let (server_side, mut client_side) = duplex(4096);
+            let handler = tokio::spawn(handle_client_stream(
+                server_side,
+                peer,
+                config,
+                stats,
+                upstream_manager,
+                replay_checker,
+                buffer_pool,
+                rng,
+                None,
+                route_runtime,
+                None,
+                ip_tracker,
+                beobachten,
+                false,
+            ));
+
+            client_side.write_all(&probe).await.unwrap();
+            client_side.shutdown().await.unwrap();
+
+            let mut observed = vec![0u8; REPLY_404.len()];
+            tokio::time::timeout(
+                Duration::from_secs(2),
+                client_side.read_exact(&mut observed),
+            )
+            .await
+            .unwrap()
+            .unwrap();
+            assert_eq!(observed, REPLY_404);
+
+            let result = tokio::time::timeout(Duration::from_secs(2), handler)
+                .await
+                .unwrap()
+                .unwrap();
+            assert!(result.is_ok());
+        }));
+    }
+
+    for task in tasks {
+        task.await.unwrap();
+    }
+
+    tokio::time::timeout(Duration::from_secs(4), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+}

src/proxy/tests/client_masking_redteam_expected_fail_tests.rs

@@ -0,0 +1,645 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use crate::crypto::sha256_hmac;
+use crate::protocol::constants::{HANDSHAKE_LEN, TLS_VERSION};
+use crate::protocol::tls;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+use tokio::time::{Duration, Instant};
+
+struct RedTeamHarness {
+    config: Arc<ProxyConfig>,
+    stats: Arc<Stats>,
+    upstream_manager: Arc<UpstreamManager>,
+    replay_checker: Arc<ReplayChecker>,
+    buffer_pool: Arc<BufferPool>,
+    rng: Arc<SecureRandom>,
+    route_runtime: Arc<RouteRuntimeController>,
+    ip_tracker: Arc<UserIpTracker>,
+    beobachten: Arc<BeobachtenStore>,
+}
+
+fn build_harness(secret_hex: &str, mask_port: u16) -> RedTeamHarness {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = mask_port;
+    cfg.censorship.mask_proxy_protocol = 0;
+    cfg.access.ignore_time_skew = true;
+    cfg.access
+        .users
+        .insert("user".to_string(), secret_hex.to_string());
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+    let upstream_manager = Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats.clone(),
+    ));
+
+    RedTeamHarness {
+        config,
+        stats,
+        upstream_manager,
+        replay_checker: Arc::new(ReplayChecker::new(256, Duration::from_secs(60))),
+        buffer_pool: Arc::new(BufferPool::new()),
+        rng: Arc::new(SecureRandom::new()),
+        route_runtime: Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        ip_tracker: Arc::new(UserIpTracker::new()),
+        beobachten: Arc::new(BeobachtenStore::new()),
+    }
+}
+
+fn make_valid_tls_client_hello(secret: &[u8], timestamp: u32, tls_len: usize, fill: u8) -> Vec<u8> {
+    assert!(
+        tls_len <= u16::MAX as usize,
+        "TLS length must fit into record header"
+    );
+
+    let total_len = 5 + tls_len;
+    let mut handshake = vec![fill; total_len];
+    handshake[0] = 0x16;
+    handshake[1] = 0x03;
+    handshake[2] = 0x01;
+    handshake[3..5].copy_from_slice(&(tls_len as u16).to_be_bytes());
+
+    let session_id_len: usize = 32;
+    handshake[tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN] = session_id_len as u8;
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN].fill(0);
+
+    let computed = sha256_hmac(secret, &handshake);
+    let mut digest = computed;
+    let ts = timestamp.to_le_bytes();
+    for i in 0..4 {
+        digest[28 + i] ^= ts[i];
+    }
+
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN]
+        .copy_from_slice(&digest);
+    handshake
+}
+
+fn wrap_tls_application_data(payload: &[u8]) -> Vec<u8> {
+    let mut record = Vec::with_capacity(5 + payload.len());
+    record.push(0x17);
+    record.extend_from_slice(&TLS_VERSION);
+    record.extend_from_slice(&(payload.len() as u16).to_be_bytes());
+    record.extend_from_slice(payload);
+    record
+}
+
+async fn run_tls_success_mtproto_fail_session(
+    secret_hex: &str,
+    secret: [u8; 16],
+    timestamp: u32,
+    tail: Vec<u8>,
+) -> Vec<u8> {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let harness = build_harness(secret_hex, backend_addr.port());
+    let client_hello = make_valid_tls_client_hello(&secret, timestamp, 600, 0x42);
+    let invalid_mtproto_record = wrap_tls_application_data(&vec![0u8; HANDSHAKE_LEN]);
+    let trailing_record = wrap_tls_application_data(&tail);
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = vec![0u8; trailing_record.len()];
+        stream.read_exact(&mut got).await.unwrap();
+        got
+    });
+
+    let (server_side, mut client_side) = duplex(262144);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.250:56900".parse().unwrap(),
+        harness.config,
+        harness.stats,
+        harness.upstream_manager,
+        harness.replay_checker,
+        harness.buffer_pool,
+        harness.rng,
+        None,
+        harness.route_runtime,
+        None,
+        harness.ip_tracker,
+        harness.beobachten,
+        false,
+    ));
+
+    client_side.write_all(&client_hello).await.unwrap();
+    let mut head = [0u8; 5];
+    client_side.read_exact(&mut head).await.unwrap();
+    assert_eq!(head[0], 0x16);
+    let body_len = u16::from_be_bytes([head[3], head[4]]) as usize;
+    let mut body = vec![0u8; body_len];
+    client_side.read_exact(&mut body).await.unwrap();
+
+    client_side
+        .write_all(&invalid_mtproto_record)
+        .await
+        .unwrap();
+    client_side
+        .write_all(&wrap_tls_application_data(&tail))
+        .await
+        .unwrap();
+
+    let forwarded = tokio::time::timeout(Duration::from_secs(3), accept_task)
+        .await
+        .unwrap()
+        .unwrap();
+
+    drop(client_side);
+    let _ = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    forwarded
+}
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: demonstrates that post-TLS fallback still forwards data to backend"]
+async fn redteam_01_backend_receives_no_data_after_mtproto_fail() {
+    let forwarded = run_tls_success_mtproto_fail_session(
+        "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+        [0xAA; 16],
+        1,
+        b"probe-a".to_vec(),
+    )
+    .await;
+    assert!(
+        forwarded.is_empty(),
+        "backend unexpectedly received fallback bytes"
+    );
+}
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: strict no-fallback policy hypothesis"]
+async fn redteam_02_backend_must_never_receive_tls_records_after_mtproto_fail() {
+    let forwarded = run_tls_success_mtproto_fail_session(
+        "abababababababababababababababab",
+        [0xAB; 16],
+        2,
+        b"probe-b".to_vec(),
+    )
+    .await;
+    assert_ne!(
+        forwarded[0], 0x17,
+        "received TLS application record despite strict policy"
+    );
+}
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: impossible timing uniformity target"]
+async fn redteam_03_masking_duration_must_be_less_than_1ms_when_backend_down() {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = 1;
+    cfg.access.ignore_time_skew = true;
+    cfg.access.users.insert(
+        "user".to_string(),
+        "acacacacacacacacacacacacacacacac".to_string(),
+    );
+
+    let harness = RedTeamHarness {
+        config: Arc::new(cfg),
+        stats: Arc::new(Stats::new()),
+        upstream_manager: Arc::new(UpstreamManager::new(
+            vec![UpstreamConfig {
+                upstream_type: UpstreamType::Direct {
+                    interface: None,
+                    bind_addresses: None,
+                },
+                weight: 1,
+                enabled: true,
+                scopes: String::new(),
+                selected_scope: String::new(),
+            }],
+            1,
+            1,
+            1,
+            1,
+            false,
+            Arc::new(Stats::new()),
+        )),
+        replay_checker: Arc::new(ReplayChecker::new(256, Duration::from_secs(60))),
+        buffer_pool: Arc::new(BufferPool::new()),
+        rng: Arc::new(SecureRandom::new()),
+        route_runtime: Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        ip_tracker: Arc::new(UserIpTracker::new()),
+        beobachten: Arc::new(BeobachtenStore::new()),
+    };
+
+    let hello = make_valid_tls_client_hello(&[0xAC; 16], 3, 600, 0x42);
+    let (server_side, mut client_side) = duplex(131072);
+
+    let started = Instant::now();
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.251:56901".parse().unwrap(),
+        harness.config,
+        harness.stats,
+        harness.upstream_manager,
+        harness.replay_checker,
+        harness.buffer_pool,
+        harness.rng,
+        None,
+        harness.route_runtime,
+        None,
+        harness.ip_tracker,
+        harness.beobachten,
+        false,
+    ));
+
+    client_side.write_all(&hello).await.unwrap();
+    client_side.shutdown().await.unwrap();
+    let _ = tokio::time::timeout(Duration::from_secs(3), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    assert!(
+        started.elapsed() < Duration::from_millis(1),
+        "fallback path took longer than 1ms"
+    );
+}
+
+macro_rules! redteam_tail_must_not_forward_case {
+    ($name:ident, $hex:expr, $secret:expr, $ts:expr, $len:expr) => {
+        #[tokio::test]
+        #[ignore = "red-team expected-fail: strict no-forwarding hypothesis"]
+        async fn $name() {
+            let mut tail = vec![0u8; $len];
+            for (i, b) in tail.iter_mut().enumerate() {
+                *b = (i as u8).wrapping_mul(31).wrapping_add(7);
+            }
+            let forwarded = run_tls_success_mtproto_fail_session($hex, $secret, $ts, tail).await;
+            assert!(
+                forwarded.is_empty(),
+                "strict model expects zero forwarded bytes, got {}",
+                forwarded.len()
+            );
+        }
+    };
+}
+
+redteam_tail_must_not_forward_case!(
+    redteam_04_tail_len_1_not_forwarded,
+    "adadadadadadadadadadadadadadadad",
+    [0xAD; 16],
+    4,
+    1
+);
+redteam_tail_must_not_forward_case!(
+    redteam_05_tail_len_2_not_forwarded,
+    "aeaeaeaeaeaeaeaeaeaeaeaeaeaeaeae",
+    [0xAE; 16],
+    5,
+    2
+);
+redteam_tail_must_not_forward_case!(
+    redteam_06_tail_len_3_not_forwarded,
+    "afafafafafafafafafafafafafafafaf",
+    [0xAF; 16],
+    6,
+    3
+);
+redteam_tail_must_not_forward_case!(
+    redteam_07_tail_len_7_not_forwarded,
+    "b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0",
+    [0xB0; 16],
+    7,
+    7
+);
+redteam_tail_must_not_forward_case!(
+    redteam_08_tail_len_15_not_forwarded,
+    "b1b1b1b1b1b1b1b1b1b1b1b1b1b1b1b1",
+    [0xB1; 16],
+    8,
+    15
+);
+redteam_tail_must_not_forward_case!(
+    redteam_09_tail_len_63_not_forwarded,
+    "b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2",
+    [0xB2; 16],
+    9,
+    63
+);
+redteam_tail_must_not_forward_case!(
+    redteam_10_tail_len_127_not_forwarded,
+    "b3b3b3b3b3b3b3b3b3b3b3b3b3b3b3b3",
+    [0xB3; 16],
+    10,
+    127
+);
+redteam_tail_must_not_forward_case!(
+    redteam_11_tail_len_255_not_forwarded,
+    "b4b4b4b4b4b4b4b4b4b4b4b4b4b4b4b4",
+    [0xB4; 16],
+    11,
+    255
+);
+redteam_tail_must_not_forward_case!(
+    redteam_12_tail_len_511_not_forwarded,
+    "b5b5b5b5b5b5b5b5b5b5b5b5b5b5b5b5",
+    [0xB5; 16],
+    12,
+    511
+);
+redteam_tail_must_not_forward_case!(
+    redteam_13_tail_len_1023_not_forwarded,
+    "b6b6b6b6b6b6b6b6b6b6b6b6b6b6b6b6",
+    [0xB6; 16],
+    13,
+    1023
+);
+redteam_tail_must_not_forward_case!(
+    redteam_14_tail_len_2047_not_forwarded,
+    "b7b7b7b7b7b7b7b7b7b7b7b7b7b7b7b7",
+    [0xB7; 16],
+    14,
+    2047
+);
+redteam_tail_must_not_forward_case!(
+    redteam_15_tail_len_4095_not_forwarded,
+    "b8b8b8b8b8b8b8b8b8b8b8b8b8b8b8b8",
+    [0xB8; 16],
+    15,
+    4095
+);
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: impossible indistinguishability envelope"]
+async fn redteam_16_timing_delta_between_paths_must_be_sub_1ms_under_concurrency() {
+    let runs = 20usize;
+    let mut durations = Vec::with_capacity(runs);
+
+    for i in 0..runs {
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let backend_addr = listener.local_addr().unwrap();
+        let secret = [0xB9u8; 16];
+        let harness = build_harness("b9b9b9b9b9b9b9b9b9b9b9b9b9b9b9b9", backend_addr.port());
+        let hello = make_valid_tls_client_hello(&secret, 100 + i as u32, 600, 0x42);
+
+        let accept_task = tokio::spawn(async move {
+            let (_stream, _) = listener.accept().await.unwrap();
+        });
+
+        let (server_side, mut client_side) = duplex(65536);
+        let handler = tokio::spawn(handle_client_stream(
+            server_side,
+            "198.51.100.252:56902".parse().unwrap(),
+            harness.config,
+            harness.stats,
+            harness.upstream_manager,
+            harness.replay_checker,
+            harness.buffer_pool,
+            harness.rng,
+            None,
+            harness.route_runtime,
+            None,
+            harness.ip_tracker,
+            harness.beobachten,
+            false,
+        ));
+
+        let started = Instant::now();
+        client_side.write_all(&hello).await.unwrap();
+        client_side.shutdown().await.unwrap();
+
+        let _ = tokio::time::timeout(Duration::from_secs(3), handler)
+            .await
+            .unwrap()
+            .unwrap();
+        let _ = tokio::time::timeout(Duration::from_secs(3), accept_task)
+            .await
+            .unwrap()
+            .unwrap();
+
+        durations.push(started.elapsed());
+    }
+
+    let min = durations.iter().copied().min().unwrap();
+    let max = durations.iter().copied().max().unwrap();
+    assert!(
+        max - min <= Duration::from_millis(1),
+        "timing spread too wide for strict anti-probing envelope"
+    );
+}
+
+async fn measure_invalid_probe_duration_ms(delay_ms: u64, tls_len: u16, body_sent: usize) -> u128 {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = 1;
+    cfg.timeouts.client_handshake = 1;
+    cfg.censorship.server_hello_delay_min_ms = delay_ms;
+    cfg.censorship.server_hello_delay_max_ms = delay_ms;
+
+    let (server_side, mut client_side) = duplex(65536);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.253:56903".parse().unwrap(),
+        Arc::new(cfg),
+        Arc::new(Stats::new()),
+        Arc::new(UpstreamManager::new(
+            vec![UpstreamConfig {
+                upstream_type: UpstreamType::Direct {
+                    interface: None,
+                    bind_addresses: None,
+                },
+                weight: 1,
+                enabled: true,
+                scopes: String::new(),
+                selected_scope: String::new(),
+            }],
+            1,
+            1,
+            1,
+            1,
+            false,
+            Arc::new(Stats::new()),
+        )),
+        Arc::new(ReplayChecker::new(256, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let mut probe = vec![0u8; 5 + body_sent];
+    probe[0] = 0x16;
+    probe[1] = 0x03;
+    probe[2] = 0x01;
+    probe[3..5].copy_from_slice(&tls_len.to_be_bytes());
+    probe[5..].fill(0xD7);
+
+    let started = Instant::now();
+    client_side.write_all(&probe).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let _ = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    started.elapsed().as_millis()
+}
+
+async fn capture_forwarded_probe_len(tls_len: u16, body_sent: usize) -> usize {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.timeouts.client_handshake = 1;
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = Vec::new();
+        let _ = tokio::time::timeout(Duration::from_secs(2), stream.read_to_end(&mut got)).await;
+        got.len()
+    });
+
+    let (server_side, mut client_side) = duplex(65536);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.254:56904".parse().unwrap(),
+        Arc::new(cfg),
+        Arc::new(Stats::new()),
+        Arc::new(UpstreamManager::new(
+            vec![UpstreamConfig {
+                upstream_type: UpstreamType::Direct {
+                    interface: None,
+                    bind_addresses: None,
+                },
+                weight: 1,
+                enabled: true,
+                scopes: String::new(),
+                selected_scope: String::new(),
+            }],
+            1,
+            1,
+            1,
+            1,
+            false,
+            Arc::new(Stats::new()),
+        )),
+        Arc::new(ReplayChecker::new(256, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let mut probe = vec![0u8; 5 + body_sent];
+    probe[0] = 0x16;
+    probe[1] = 0x03;
+    probe[2] = 0x01;
+    probe[3..5].copy_from_slice(&tls_len.to_be_bytes());
+    probe[5..].fill(0xBC);
+
+    client_side.write_all(&probe).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let _ = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    tokio::time::timeout(Duration::from_secs(4), accept_task)
+        .await
+        .unwrap()
+        .unwrap()
+}
+
+macro_rules! redteam_timing_envelope_case {
+    ($name:ident, $delay_ms:expr, $tls_len:expr, $body_sent:expr, $max_ms:expr) => {
+        #[tokio::test]
+        #[ignore = "red-team expected-fail: unrealistically tight reject timing envelope"]
+        async fn $name() {
+            let elapsed_ms =
+                measure_invalid_probe_duration_ms($delay_ms, $tls_len, $body_sent).await;
+            assert!(
+                elapsed_ms <= $max_ms,
+                "timing envelope violated: elapsed={}ms, max={}ms",
+                elapsed_ms,
+                $max_ms
+            );
+        }
+    };
+}
+
+macro_rules! redteam_constant_shape_case {
+    ($name:ident, $tls_len:expr, $body_sent:expr, $expected_len:expr) => {
+        #[tokio::test]
+        #[ignore = "red-team expected-fail: strict constant-shape backend fingerprint hypothesis"]
+        async fn $name() {
+            let got = capture_forwarded_probe_len($tls_len, $body_sent).await;
+            assert_eq!(
+                got, $expected_len,
+                "fingerprint shape mismatch: got={} expected={} (strict constant-shape model)",
+                got, $expected_len
+            );
+        }
+    };
+}
+
+redteam_timing_envelope_case!(redteam_17_timing_env_very_tight_00, 700, 600, 0, 3);
+redteam_timing_envelope_case!(redteam_18_timing_env_very_tight_01, 700, 600, 1, 3);
+redteam_timing_envelope_case!(redteam_19_timing_env_very_tight_02, 700, 600, 7, 3);
+redteam_timing_envelope_case!(redteam_20_timing_env_very_tight_03, 700, 600, 17, 3);
+redteam_timing_envelope_case!(redteam_21_timing_env_very_tight_04, 700, 600, 31, 3);
+redteam_timing_envelope_case!(redteam_22_timing_env_very_tight_05, 700, 600, 63, 3);
+redteam_timing_envelope_case!(redteam_23_timing_env_very_tight_06, 700, 600, 127, 3);
+redteam_timing_envelope_case!(redteam_24_timing_env_very_tight_07, 700, 600, 255, 3);
+redteam_timing_envelope_case!(redteam_25_timing_env_very_tight_08, 700, 600, 511, 3);
+redteam_timing_envelope_case!(redteam_26_timing_env_very_tight_09, 700, 600, 1023, 3);
+redteam_timing_envelope_case!(redteam_27_timing_env_very_tight_10, 700, 600, 2047, 3);
+redteam_timing_envelope_case!(redteam_28_timing_env_very_tight_11, 700, 600, 4095, 3);
+
+redteam_constant_shape_case!(redteam_29_constant_shape_00, 600, 0, 517);
+redteam_constant_shape_case!(redteam_30_constant_shape_01, 600, 1, 517);
+redteam_constant_shape_case!(redteam_31_constant_shape_02, 600, 7, 517);
+redteam_constant_shape_case!(redteam_32_constant_shape_03, 600, 17, 517);
+redteam_constant_shape_case!(redteam_33_constant_shape_04, 600, 31, 517);
+redteam_constant_shape_case!(redteam_34_constant_shape_05, 600, 63, 517);
+redteam_constant_shape_case!(redteam_35_constant_shape_06, 600, 127, 517);
+redteam_constant_shape_case!(redteam_36_constant_shape_07, 600, 255, 517);
+redteam_constant_shape_case!(redteam_37_constant_shape_08, 600, 511, 517);
+redteam_constant_shape_case!(redteam_38_constant_shape_09, 600, 1023, 517);
+redteam_constant_shape_case!(redteam_39_constant_shape_10, 600, 2047, 517);
+redteam_constant_shape_case!(redteam_40_constant_shape_11, 600, 4095, 517);

src/proxy/tests/client_masking_replay_timing_security_tests.rs

@@ -0,0 +1,167 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use crate::crypto::sha256_hmac;
+use crate::protocol::constants::{HANDSHAKE_LEN, TLS_VERSION};
+use crate::protocol::tls;
+use std::sync::Arc;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::time::{Duration, Instant};
+
+fn new_upstream_manager(stats: Arc<Stats>) -> Arc<UpstreamManager> {
+    Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats,
+    ))
+}
+
+fn make_valid_tls_client_hello(secret: &[u8], timestamp: u32, tls_len: usize, fill: u8) -> Vec<u8> {
+    let total_len = 5 + tls_len;
+    let mut handshake = vec![fill; total_len];
+
+    handshake[0] = 0x16;
+    handshake[1] = 0x03;
+    handshake[2] = 0x01;
+    handshake[3..5].copy_from_slice(&(tls_len as u16).to_be_bytes());
+
+    let session_id_len: usize = 32;
+    handshake[tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN] = session_id_len as u8;
+
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN].fill(0);
+    let computed = sha256_hmac(secret, &handshake);
+    let mut digest = computed;
+    let ts = timestamp.to_le_bytes();
+    for i in 0..4 {
+        digest[28 + i] ^= ts[i];
+    }
+
+    handshake[tls::TLS_DIGEST_POS..tls::TLS_DIGEST_POS + tls::TLS_DIGEST_LEN]
+        .copy_from_slice(&digest);
+    handshake
+}
+
+async fn run_replay_candidate_session(
+    replay_checker: Arc<ReplayChecker>,
+    hello: &[u8],
+    peer: SocketAddr,
+    drive_mtproto_fail: bool,
+) -> Duration {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = 1;
+    cfg.censorship.mask_timing_normalization_enabled = false;
+    cfg.access.ignore_time_skew = true;
+    cfg.access.users.insert(
+        "user".to_string(),
+        "abababababababababababababababab".to_string(),
+    );
+
+    let config = Arc::new(cfg);
+    let stats = Arc::new(Stats::new());
+    let beobachten = Arc::new(BeobachtenStore::new());
+
+    let (server_side, mut client_side) = duplex(65536);
+    let started = Instant::now();
+
+    let task = tokio::spawn(handle_client_stream(
+        server_side,
+        peer,
+        config,
+        stats.clone(),
+        new_upstream_manager(stats),
+        replay_checker,
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        beobachten,
+        false,
+    ));
+
+    client_side.write_all(hello).await.unwrap();
+
+    if drive_mtproto_fail {
+        let mut server_hello_head = [0u8; 5];
+        client_side
+            .read_exact(&mut server_hello_head)
+            .await
+            .unwrap();
+        assert_eq!(server_hello_head[0], 0x16);
+        let body_len = u16::from_be_bytes([server_hello_head[3], server_hello_head[4]]) as usize;
+        let mut body = vec![0u8; body_len];
+        client_side.read_exact(&mut body).await.unwrap();
+
+        let mut invalid_mtproto_record = Vec::with_capacity(5 + HANDSHAKE_LEN);
+        invalid_mtproto_record.push(0x17);
+        invalid_mtproto_record.extend_from_slice(&TLS_VERSION);
+        invalid_mtproto_record.extend_from_slice(&(HANDSHAKE_LEN as u16).to_be_bytes());
+        invalid_mtproto_record.extend_from_slice(&vec![0u8; HANDSHAKE_LEN]);
+        client_side
+            .write_all(&invalid_mtproto_record)
+            .await
+            .unwrap();
+        client_side
+            .write_all(b"GET /replay-fallback HTTP/1.1\r\nHost: x\r\n\r\n")
+            .await
+            .unwrap();
+    }
+
+    client_side.shutdown().await.unwrap();
+
+    let _ = tokio::time::timeout(Duration::from_secs(4), task)
+        .await
+        .unwrap()
+        .unwrap();
+
+    started.elapsed()
+}
+
+#[tokio::test]
+async fn replay_reject_still_honors_masking_timing_budget() {
+    let replay_checker = Arc::new(ReplayChecker::new(256, Duration::from_secs(60)));
+    let hello = make_valid_tls_client_hello(&[0xAB; 16], 7, 600, 0x51);
+
+    let seed_elapsed = run_replay_candidate_session(
+        Arc::clone(&replay_checker),
+        &hello,
+        "198.51.100.201:58001".parse().unwrap(),
+        true,
+    )
+    .await;
+
+    assert!(
+        seed_elapsed >= Duration::from_millis(40) && seed_elapsed < Duration::from_millis(250),
+        "seed replay-candidate run must honor masking timing budget without unbounded delay"
+    );
+
+    let replay_elapsed = run_replay_candidate_session(
+        Arc::clone(&replay_checker),
+        &hello,
+        "198.51.100.202:58002".parse().unwrap(),
+        false,
+    )
+    .await;
+
+    assert!(
+        replay_elapsed >= Duration::from_millis(40) && replay_elapsed < Duration::from_millis(250),
+        "replay rejection path must still satisfy masking timing budget without unbounded DB/CPU delay"
+    );
+}

src/proxy/tests/client_masking_shape_classifier_fuzz_redteam_expected_fail_tests.rs

@@ -0,0 +1,246 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use std::sync::Arc;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+use tokio::time::Duration;
+
+fn new_upstream_manager(stats: Arc<Stats>) -> Arc<UpstreamManager> {
+    Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats,
+    ))
+}
+
+async fn run_probe_capture(
+    body_sent: usize,
+    tls_len: u16,
+    enable_shape_hardening: bool,
+    floor: usize,
+    cap: usize,
+) -> usize {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.censorship.mask_shape_hardening = enable_shape_hardening;
+    cfg.censorship.mask_shape_bucket_floor_bytes = floor;
+    cfg.censorship.mask_shape_bucket_cap_bytes = cap;
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = Vec::new();
+        let _ = tokio::time::timeout(Duration::from_secs(2), stream.read_to_end(&mut got)).await;
+        got.len()
+    });
+
+    let (server_side, mut client_side) = duplex(65536);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.214:57014".parse().unwrap(),
+        Arc::new(cfg),
+        Arc::new(Stats::new()),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let mut probe = vec![0u8; 5 + body_sent];
+    probe[0] = 0x16;
+    probe[1] = 0x03;
+    probe[2] = 0x01;
+    probe[3..5].copy_from_slice(&tls_len.to_be_bytes());
+    probe[5..].fill(0x66);
+
+    client_side.write_all(&probe).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let _ = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    tokio::time::timeout(Duration::from_secs(4), accept_task)
+        .await
+        .unwrap()
+        .unwrap()
+}
+
+fn pearson_corr(xs: &[f64], ys: &[f64]) -> f64 {
+    if xs.len() != ys.len() || xs.is_empty() {
+        return 0.0;
+    }
+
+    let n = xs.len() as f64;
+    let mean_x = xs.iter().sum::<f64>() / n;
+    let mean_y = ys.iter().sum::<f64>() / n;
+
+    let mut cov = 0.0;
+    let mut var_x = 0.0;
+    let mut var_y = 0.0;
+
+    for (&x, &y) in xs.iter().zip(ys.iter()) {
+        let dx = x - mean_x;
+        let dy = y - mean_y;
+        cov += dx * dy;
+        var_x += dx * dx;
+        var_y += dy * dy;
+    }
+
+    if var_x == 0.0 || var_y == 0.0 {
+        return 0.0;
+    }
+
+    cov / (var_x.sqrt() * var_y.sqrt())
+}
+
+fn lcg_sizes(count: usize, floor: usize, cap: usize) -> Vec<usize> {
+    let mut x = 0x9E3779B97F4A7C15u64;
+    let span = cap.saturating_mul(3);
+    let mut out = Vec::with_capacity(count + 8);
+
+    for _ in 0..count {
+        x = x
+            .wrapping_mul(6364136223846793005)
+            .wrapping_add(1442695040888963407);
+        let v = (x as usize) % span.max(1);
+        out.push(v);
+    }
+
+    // Inject edge and boundary-heavy probes.
+    out.extend_from_slice(&[
+        0,
+        floor.saturating_sub(1),
+        floor,
+        floor.saturating_add(1),
+        cap.saturating_sub(1),
+        cap,
+        cap.saturating_add(1),
+        cap.saturating_mul(2),
+    ]);
+    out
+}
+
+async fn collect_distribution(
+    sizes: &[usize],
+    hardening: bool,
+    floor: usize,
+    cap: usize,
+) -> Vec<usize> {
+    let mut out = Vec::with_capacity(sizes.len());
+    for &body in sizes {
+        out.push(run_probe_capture(body, 1200, hardening, floor, cap).await);
+    }
+    out
+}
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: strict decorrelation target for hardened output lengths"]
+async fn redteam_fuzz_01_hardened_output_length_correlation_should_be_below_0_2() {
+    let floor = 512usize;
+    let cap = 4096usize;
+    let sizes = lcg_sizes(24, floor, cap);
+
+    let hardened = collect_distribution(&sizes, true, floor, cap).await;
+    let x: Vec<f64> = sizes.iter().map(|v| *v as f64).collect();
+    let y_hard: Vec<f64> = hardened.iter().map(|v| *v as f64).collect();
+
+    let corr_hard = pearson_corr(&x, &y_hard).abs();
+    println!(
+        "redteam_fuzz corr_hardened={corr_hard:.4} samples={}",
+        sizes.len()
+    );
+
+    assert!(
+        corr_hard < 0.2,
+        "strict model expects near-zero size correlation; observed corr={corr_hard:.4}"
+    );
+}
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: strict class-collapse ratio target"]
+async fn redteam_fuzz_02_hardened_unique_output_ratio_should_be_below_5pct() {
+    let floor = 512usize;
+    let cap = 4096usize;
+    let sizes = lcg_sizes(24, floor, cap);
+
+    let hardened = collect_distribution(&sizes, true, floor, cap).await;
+
+    let in_unique = {
+        let mut s = std::collections::BTreeSet::new();
+        for v in &sizes {
+            s.insert(*v);
+        }
+        s.len()
+    };
+
+    let out_unique = {
+        let mut s = std::collections::BTreeSet::new();
+        for v in &hardened {
+            s.insert(*v);
+        }
+        s.len()
+    };
+
+    let ratio = out_unique as f64 / in_unique as f64;
+    println!(
+        "redteam_fuzz unique_ratio_hardened={ratio:.4} out_unique={} in_unique={}",
+        out_unique, in_unique
+    );
+
+    assert!(
+        ratio <= 0.05,
+        "strict model expects near-total collapse; observed ratio={ratio:.4}"
+    );
+}
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: strict separability improvement target"]
+async fn redteam_fuzz_03_hardened_signal_must_be_10x_lower_than_plain() {
+    let floor = 512usize;
+    let cap = 4096usize;
+    let sizes = lcg_sizes(24, floor, cap);
+
+    let plain = collect_distribution(&sizes, false, floor, cap).await;
+    let hardened = collect_distribution(&sizes, true, floor, cap).await;
+
+    let x: Vec<f64> = sizes.iter().map(|v| *v as f64).collect();
+    let y_plain: Vec<f64> = plain.iter().map(|v| *v as f64).collect();
+    let y_hard: Vec<f64> = hardened.iter().map(|v| *v as f64).collect();
+
+    let corr_plain = pearson_corr(&x, &y_plain).abs();
+    let corr_hard = pearson_corr(&x, &y_hard).abs();
+
+    println!("redteam_fuzz corr_plain={corr_plain:.4} corr_hardened={corr_hard:.4}");
+
+    assert!(
+        corr_hard <= corr_plain * 0.1,
+        "strict model expects 10x suppression; plain={corr_plain:.4} hardened={corr_hard:.4}"
+    );
+}

src/proxy/tests/client_masking_shape_hardening_adversarial_tests.rs

@@ -0,0 +1,179 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use std::sync::Arc;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+use tokio::time::Duration;
+
+fn new_upstream_manager(stats: Arc<Stats>) -> Arc<UpstreamManager> {
+    Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats,
+    ))
+}
+
+fn expected_bucket(total: usize, floor: usize, cap: usize) -> usize {
+    if total == 0 || floor == 0 || cap < floor {
+        return total;
+    }
+
+    if total >= cap {
+        return total;
+    }
+
+    let mut bucket = floor;
+    while bucket < total {
+        match bucket.checked_mul(2) {
+            Some(next) => bucket = next,
+            None => return total,
+        }
+        if bucket > cap {
+            return cap;
+        }
+    }
+    bucket
+}
+
+async fn run_probe_capture(
+    body_sent: usize,
+    tls_len: u16,
+    enable_shape_hardening: bool,
+    floor: usize,
+    cap: usize,
+) -> Vec<u8> {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.censorship.mask_shape_hardening = enable_shape_hardening;
+    cfg.censorship.mask_shape_bucket_floor_bytes = floor;
+    cfg.censorship.mask_shape_bucket_cap_bytes = cap;
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = Vec::new();
+        let _ = tokio::time::timeout(Duration::from_secs(2), stream.read_to_end(&mut got)).await;
+        got
+    });
+
+    let (server_side, mut client_side) = duplex(65536);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.199:56999".parse().unwrap(),
+        Arc::new(cfg),
+        Arc::new(Stats::new()),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let mut probe = vec![0u8; 5 + body_sent];
+    probe[0] = 0x16;
+    probe[1] = 0x03;
+    probe[2] = 0x01;
+    probe[3..5].copy_from_slice(&tls_len.to_be_bytes());
+    probe[5..].fill(0x66);
+
+    client_side.write_all(&probe).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let result = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+    assert!(result.is_ok());
+
+    tokio::time::timeout(Duration::from_secs(4), accept_task)
+        .await
+        .unwrap()
+        .unwrap()
+}
+
+#[tokio::test]
+async fn shape_hardening_non_power_of_two_cap_collapses_probe_classes() {
+    let floor = 1000usize;
+    let cap = 1500usize;
+
+    let low = run_probe_capture(1195, 700, true, floor, cap).await;
+    let high = run_probe_capture(1494, 700, true, floor, cap).await;
+
+    assert_eq!(low.len(), 1500);
+    assert_eq!(high.len(), 1500);
+}
+
+#[tokio::test]
+async fn shape_hardening_disabled_keeps_non_power_of_two_cap_lengths_distinct() {
+    let floor = 1000usize;
+    let cap = 1500usize;
+
+    let low = run_probe_capture(1195, 700, false, floor, cap).await;
+    let high = run_probe_capture(1494, 700, false, floor, cap).await;
+
+    assert_eq!(low.len(), 1200);
+    assert_eq!(high.len(), 1499);
+}
+
+#[tokio::test]
+async fn shape_hardening_parallel_stress_collapses_sub_cap_probes() {
+    let floor = 1000usize;
+    let cap = 1500usize;
+    let mut tasks = Vec::new();
+
+    for idx in 0..24usize {
+        let body = 1001 + (idx * 19 % 480);
+        tasks.push(tokio::spawn(async move {
+            run_probe_capture(body, 1200, true, floor, cap).await.len()
+        }));
+    }
+
+    for task in tasks {
+        let observed = task.await.unwrap();
+        assert_eq!(observed, 1500);
+    }
+}
+
+#[tokio::test]
+async fn shape_hardening_light_fuzz_matches_bucket_oracle() {
+    let floor = 512usize;
+    let cap = 4096usize;
+
+    for step in 1usize..=36usize {
+        let total = 1 + (((step * 313) ^ (step << 7)) % (cap + 300));
+        let body = total.saturating_sub(5);
+
+        let got = run_probe_capture(body, 650, true, floor, cap).await;
+        let expected = expected_bucket(total, floor, cap);
+        assert_eq!(
+            got.len(),
+            expected,
+            "step={step} total={total} expected={expected} got={} ",
+            got.len()
+        );
+    }
+}

src/proxy/tests/client_masking_shape_hardening_redteam_expected_fail_tests.rs

@@ -0,0 +1,238 @@
+use super::*;
+use crate::config::{UpstreamConfig, UpstreamType};
+use std::sync::Arc;
+use tokio::io::{AsyncReadExt, AsyncWriteExt, duplex};
+use tokio::net::TcpListener;
+use tokio::time::{Duration, Instant};
+
+fn new_upstream_manager(stats: Arc<Stats>) -> Arc<UpstreamManager> {
+    Arc::new(UpstreamManager::new(
+        vec![UpstreamConfig {
+            upstream_type: UpstreamType::Direct {
+                interface: None,
+                bind_addresses: None,
+            },
+            weight: 1,
+            enabled: true,
+            scopes: String::new(),
+            selected_scope: String::new(),
+        }],
+        1,
+        1,
+        1,
+        1,
+        false,
+        stats,
+    ))
+}
+
+async fn run_probe_capture(
+    body_sent: usize,
+    tls_len: u16,
+    enable_shape_hardening: bool,
+    floor: usize,
+    cap: usize,
+) -> Vec<u8> {
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let backend_addr = listener.local_addr().unwrap();
+
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = backend_addr.port();
+    cfg.censorship.mask_shape_hardening = enable_shape_hardening;
+    cfg.censorship.mask_shape_bucket_floor_bytes = floor;
+    cfg.censorship.mask_shape_bucket_cap_bytes = cap;
+
+    let accept_task = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut got = Vec::new();
+        let _ = tokio::time::timeout(Duration::from_secs(2), stream.read_to_end(&mut got)).await;
+        got
+    });
+
+    let (server_side, mut client_side) = duplex(65536);
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.211:57011".parse().unwrap(),
+        Arc::new(cfg),
+        Arc::new(Stats::new()),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let mut probe = vec![0u8; 5 + body_sent];
+    probe[0] = 0x16;
+    probe[1] = 0x03;
+    probe[2] = 0x01;
+    probe[3..5].copy_from_slice(&tls_len.to_be_bytes());
+    probe[5..].fill(0x66);
+
+    client_side.write_all(&probe).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let _ = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    tokio::time::timeout(Duration::from_secs(4), accept_task)
+        .await
+        .unwrap()
+        .unwrap()
+}
+
+async fn measure_reject_ms(body_sent: usize) -> u128 {
+    let mut cfg = ProxyConfig::default();
+    cfg.general.beobachten = false;
+    cfg.timeouts.client_handshake = 1;
+    cfg.censorship.mask = true;
+    cfg.censorship.mask_unix_sock = None;
+    cfg.censorship.mask_host = Some("127.0.0.1".to_string());
+    cfg.censorship.mask_port = 1;
+    cfg.censorship.server_hello_delay_min_ms = 700;
+    cfg.censorship.server_hello_delay_max_ms = 700;
+
+    let (server_side, mut client_side) = duplex(65536);
+    let started = Instant::now();
+
+    let handler = tokio::spawn(handle_client_stream(
+        server_side,
+        "198.51.100.212:57012".parse().unwrap(),
+        Arc::new(cfg),
+        Arc::new(Stats::new()),
+        new_upstream_manager(Arc::new(Stats::new())),
+        Arc::new(ReplayChecker::new(128, Duration::from_secs(60))),
+        Arc::new(BufferPool::new()),
+        Arc::new(SecureRandom::new()),
+        None,
+        Arc::new(RouteRuntimeController::new(RelayRouteMode::Direct)),
+        None,
+        Arc::new(UserIpTracker::new()),
+        Arc::new(BeobachtenStore::new()),
+        false,
+    ));
+
+    let mut probe = vec![0u8; 5 + body_sent];
+    probe[0] = 0x16;
+    probe[1] = 0x03;
+    probe[2] = 0x01;
+    probe[3..5].copy_from_slice(&600u16.to_be_bytes());
+    probe[5..].fill(0x44);
+
+    client_side.write_all(&probe).await.unwrap();
+    client_side.shutdown().await.unwrap();
+
+    let _ = tokio::time::timeout(Duration::from_secs(4), handler)
+        .await
+        .unwrap()
+        .unwrap();
+
+    started.elapsed().as_millis()
+}
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: above-cap exact length still leaks classifier signal"]
+async fn redteam_shape_01_above_cap_flows_should_collapse_to_single_class() {
+    let floor = 512usize;
+    let cap = 4096usize;
+
+    let a = run_probe_capture(5000, 7000, true, floor, cap).await;
+    let b = run_probe_capture(6000, 7000, true, floor, cap).await;
+
+    assert_eq!(
+        a.len(),
+        b.len(),
+        "strict anti-classifier model expects same backend length class above cap"
+    );
+}
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: current padding bytes are deterministic zeros"]
+async fn redteam_shape_02_padding_tail_must_be_non_deterministic() {
+    let floor = 512usize;
+    let cap = 4096usize;
+    let got = run_probe_capture(17, 600, true, floor, cap).await;
+
+    assert!(got.len() > 22, "test requires padding tail to exist");
+
+    let tail = &got[22..];
+    assert!(
+        tail.iter().any(|b| *b != 0),
+        "padding tail is fully zeroed and thus deterministic"
+    );
+}
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: exact-floor probes still expose boundary class"]
+async fn redteam_shape_03_exact_floor_input_should_not_be_fixed_point() {
+    let floor = 512usize;
+    let cap = 4096usize;
+    let got = run_probe_capture(507, 600, true, floor, cap).await;
+
+    assert!(
+        got.len() > floor,
+        "strict model expects extra blur even when input lands exactly on floor"
+    );
+}
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: strict one-bucket collapse hypothesis"]
+async fn redteam_shape_04_all_sub_cap_sizes_should_collapse_to_single_size() {
+    let floor = 512usize;
+    let cap = 4096usize;
+    let classes = [
+        17usize, 63usize, 255usize, 511usize, 1023usize, 2047usize, 3071usize,
+    ];
+
+    let mut observed = Vec::new();
+    for body in classes {
+        observed.push(run_probe_capture(body, 1200, true, floor, cap).await.len());
+    }
+
+    let first = observed[0];
+    for v in observed {
+        assert_eq!(
+            v, first,
+            "strict model expects one collapsed class across all sub-cap probes"
+        );
+    }
+}
+
+#[tokio::test]
+#[ignore = "red-team expected-fail: over-strict micro-timing invariance"]
+async fn redteam_shape_05_reject_timing_spread_should_be_under_2ms() {
+    let classes = [17usize, 511usize, 1023usize, 2047usize, 4095usize];
+    let mut values = Vec::new();
+
+    for class in classes {
+        values.push(measure_reject_ms(class).await);
+    }
+
+    let min = *values.iter().min().unwrap();
+    let max = *values.iter().max().unwrap();
+    assert!(
+        min == 700 && max == 700,
+        "strict model requires exact 700ms for every malformed class: min={min}ms max={max}ms"
+    );
+}
+
+#[test]
+#[ignore = "red-team expected-fail: secure-by-default hypothesis"]
+fn redteam_shape_06_shape_hardening_should_be_secure_by_default() {
+    let cfg = ProxyConfig::default();
+    assert!(
+        cfg.censorship.mask_shape_hardening,
+        "strict model expects shape hardening enabled by default"
+    );
+}