Merge pull request #344 from telemt/bump

Update Cargo.toml

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "telemt"
-version = "3.3.0"
+version = "3.3.5"
 edition = "2024"
 
 [dependencies]

README.md

@@ -3,7 +3,7 @@
 ***Löst Probleme, bevor andere überhaupt wissen, dass sie existieren*** / ***It solves problems before others even realize they exist***
 
 **Telemt** is a fast, secure, and feature-rich server written in Rust: it fully implements the official Telegram proxy algo and adds many production-ready improvements such as:
-- ME Pool + Reader/Writer + Registry + Refill + Adaptive Floor + Trio-State + Generation Lifecycle
+- [ME Pool + Reader/Writer + Registry + Refill + Adaptive Floor + Trio-State + Generation Lifecycle](https://github.com/telemt/telemt/blob/main/docs/model/MODEL.en.md)
 - [Full-covered API w/ management](https://github.com/telemt/telemt/blob/main/docs/API.md)
 - Anti-Replay on Sliding Window
 - Prometheus-format Metrics
@@ -19,18 +19,18 @@
 
 ### 🇷🇺 RU
 
-#### Релиз 3.0.15 — 25 февраля
+#### Релиз 3.3.3 LTS - 6 марта
 
-25 февраля мы выпустили версию **3.0.15**
+6 марта мы выпустили Telemt **3.3.3**
 
-Мы предполагаем, что она станет завершающей версией поколения 3.0 и уже сейчас мы рассматриваем её как **LTS-кандидата** для версии **3.1.0**!
+Это первая версия telemt работающая в комплексных условиях и при этом предоставляющая API
 
-После нескольких дней детального анализа особенностей работы Middle-End мы спроектировали и реализовали продуманный режим **ротации ME Writer**. Данный режим позволяет поддерживать стабильно высокую производительность в long-run сценариях без возникновения ошибок, связанных с некорректной конфигурацией прокси
+В ней используется новый алгоритм - ME NoWait, который вместе с Adaptive Floor и моделью усовершенствованного доступа к KDF Fingerprint на RwLock позволяет достигать максимальную производительность, даже в условиях lossy-сети
 
 Будем рады вашему фидбеку и предложениям по улучшению — особенно в части **статистики** и **UX**
 
 Релиз:  
-[3.0.15](https://github.com/telemt/telemt/releases/tag/3.0.15)
+[3.3.3](https://github.com/telemt/telemt/releases/tag/3.3.3)
 
 ---
 
@@ -47,18 +47,18 @@
 
 ### 🇬🇧 EN
 
-#### Release 3.0.15 — February 25
+#### Release 3.3.3 LTS - March 6
 
-On February 25, we released version **3.0.15**
+On March 6, we released Telemt **3.3.3**
 
-We expect this to become the final release of the 3.0 generation and at this point, we already see it as a strong **LTS candidate** for the upcoming **3.1.0** release!
+This is the first telemt's version designed to operate reliably in complex network conditions while also providing a runtime API!
 
-After several days of deep analysis of Middle-End behavior, we designed and implemented a well-engineered **ME Writer rotation mode**. This mode enables sustained high throughput in long-run scenarios while preventing proxy misconfiguration errors
+The release introduces a new algorithm — ME NoWait, which combined with Adaptive Floor and an improved KDF Fingerprint access model based on RwLock, it enables the system to achieve maximum performance even in lossy network environments
 
 We are looking forward to your feedback and improvement proposals — especially regarding **statistics** and **UX**
 
 Release:  
-[3.0.15](https://github.com/telemt/telemt/releases/tag/3.0.15)
+[3.3.3](https://github.com/telemt/telemt/releases/tag/3.3.3)
 
 ---
 

docs/API.md

@@ -16,6 +16,10 @@ API runtime is configured in `[server.api]`.
 | `request_body_limit_bytes` | `usize` | `65536` | Maximum request body size. Must be `> 0`. |
 | `minimal_runtime_enabled` | `bool` | `false` | Enables runtime snapshot endpoints requiring ME pool read-lock aggregation. |
 | `minimal_runtime_cache_ttl_ms` | `u64` | `1000` | Cache TTL for minimal snapshots. `0` disables cache; valid range is `[0, 60000]`. |
+| `runtime_edge_enabled` | `bool` | `false` | Enables runtime edge endpoints with cached aggregation payloads. |
+| `runtime_edge_cache_ttl_ms` | `u64` | `1000` | Cache TTL for runtime edge summary payloads. `0` disables cache. |
+| `runtime_edge_top_n` | `usize` | `10` | Top-N rows for runtime edge leaderboard payloads. |
+| `runtime_edge_events_capacity` | `usize` | `256` | Ring-buffer size for `/v1/runtime/events/recent`. |
 | `read_only` | `bool` | `false` | Disables mutating endpoints. |
 
 `server.admin_api` is accepted as an alias for backward compatibility.
@@ -24,6 +28,9 @@ Runtime validation for API config:
 - `server.api.listen` must be a valid `IP:PORT`.
 - `server.api.request_body_limit_bytes` must be `> 0`.
 - `server.api.minimal_runtime_cache_ttl_ms` must be within `[0, 60000]`.
+- `server.api.runtime_edge_cache_ttl_ms` must be within `[0, 60000]`.
+- `server.api.runtime_edge_top_n` must be within `[1, 1000]`.
+- `server.api.runtime_edge_events_capacity` must be within `[16, 4096]`.
 
 ## Protocol Contract
 
@@ -76,12 +83,23 @@ Notes:
 | Method | Path | Body | Success | `data` contract |
 | --- | --- | --- | --- | --- |
 | `GET` | `/v1/health` | none | `200` | `HealthData` |
+| `GET` | `/v1/system/info` | none | `200` | `SystemInfoData` |
+| `GET` | `/v1/runtime/gates` | none | `200` | `RuntimeGatesData` |
+| `GET` | `/v1/limits/effective` | none | `200` | `EffectiveLimitsData` |
+| `GET` | `/v1/security/posture` | none | `200` | `SecurityPostureData` |
+| `GET` | `/v1/security/whitelist` | none | `200` | `SecurityWhitelistData` |
 | `GET` | `/v1/stats/summary` | none | `200` | `SummaryData` |
 | `GET` | `/v1/stats/zero/all` | none | `200` | `ZeroAllData` |
 | `GET` | `/v1/stats/upstreams` | none | `200` | `UpstreamsData` |
 | `GET` | `/v1/stats/minimal/all` | none | `200` | `MinimalAllData` |
 | `GET` | `/v1/stats/me-writers` | none | `200` | `MeWritersData` |
 | `GET` | `/v1/stats/dcs` | none | `200` | `DcStatusData` |
+| `GET` | `/v1/runtime/me_pool_state` | none | `200` | `RuntimeMePoolStateData` |
+| `GET` | `/v1/runtime/me_quality` | none | `200` | `RuntimeMeQualityData` |
+| `GET` | `/v1/runtime/upstream_quality` | none | `200` | `RuntimeUpstreamQualityData` |
+| `GET` | `/v1/runtime/nat_stun` | none | `200` | `RuntimeNatStunData` |
+| `GET` | `/v1/runtime/connections/summary` | none | `200` | `RuntimeEdgeConnectionsSummaryData` |
+| `GET` | `/v1/runtime/events/recent` | none | `200` | `RuntimeEdgeEventsData` |
 | `GET` | `/v1/stats/users` | none | `200` | `UserInfo[]` |
 | `GET` | `/v1/users` | none | `200` | `UserInfo[]` |
 | `POST` | `/v1/users` | `CreateUserRequest` | `201` | `CreateUserResponse` |
@@ -176,6 +194,113 @@ Note: the request contract is defined, but the corresponding route currently ret
 | `handshake_timeouts_total` | `u64` | Handshake timeout count. |
 | `configured_users` | `usize` | Number of configured users in config. |
 
+### `SystemInfoData`
+| Field | Type | Description |
+| --- | --- | --- |
+| `version` | `string` | Binary version (`CARGO_PKG_VERSION`). |
+| `target_arch` | `string` | Target architecture (`std::env::consts::ARCH`). |
+| `target_os` | `string` | Target OS (`std::env::consts::OS`). |
+| `build_profile` | `string` | Build profile (`PROFILE` env when available). |
+| `git_commit` | `string?` | Optional commit hash from build env metadata. |
+| `build_time_utc` | `string?` | Optional build timestamp from build env metadata. |
+| `rustc_version` | `string?` | Optional compiler version from build env metadata. |
+| `process_started_at_epoch_secs` | `u64` | Process start time as Unix epoch seconds. |
+| `uptime_seconds` | `f64` | Process uptime in seconds. |
+| `config_path` | `string` | Active config file path used by runtime. |
+| `config_hash` | `string` | SHA-256 hash of current config content (same value as envelope `revision`). |
+| `config_reload_count` | `u64` | Number of successfully observed config updates since process start. |
+| `last_config_reload_epoch_secs` | `u64?` | Unix epoch seconds of the latest observed config reload; null/absent before first reload. |
+
+### `RuntimeGatesData`
+| Field | Type | Description |
+| --- | --- | --- |
+| `accepting_new_connections` | `bool` | Current admission-gate state for new listener accepts. |
+| `conditional_cast_enabled` | `bool` | Whether conditional ME admission logic is enabled (`general.use_middle_proxy`). |
+| `me_runtime_ready` | `bool` | Current ME runtime readiness status used for conditional gate decisions. |
+| `me2dc_fallback_enabled` | `bool` | Whether ME -> direct fallback is enabled. |
+| `use_middle_proxy` | `bool` | Current transport mode preference. |
+
+### `EffectiveLimitsData`
+| Field | Type | Description |
+| --- | --- | --- |
+| `update_every_secs` | `u64` | Effective unified updater interval. |
+| `me_reinit_every_secs` | `u64` | Effective ME periodic reinit interval. |
+| `me_pool_force_close_secs` | `u64` | Effective stale-writer force-close timeout. |
+| `timeouts` | `EffectiveTimeoutLimits` | Effective timeout policy snapshot. |
+| `upstream` | `EffectiveUpstreamLimits` | Effective upstream connect/retry limits. |
+| `middle_proxy` | `EffectiveMiddleProxyLimits` | Effective ME pool/floor/reconnect limits. |
+| `user_ip_policy` | `EffectiveUserIpPolicyLimits` | Effective unique-IP policy mode/window. |
+
+#### `EffectiveTimeoutLimits`
+| Field | Type | Description |
+| --- | --- | --- |
+| `client_handshake_secs` | `u64` | Client handshake timeout. |
+| `tg_connect_secs` | `u64` | Upstream Telegram connect timeout. |
+| `client_keepalive_secs` | `u64` | Client keepalive interval. |
+| `client_ack_secs` | `u64` | ACK timeout. |
+| `me_one_retry` | `u8` | Fast retry count for single-endpoint ME DC. |
+| `me_one_timeout_ms` | `u64` | Fast retry timeout per attempt for single-endpoint ME DC. |
+
+#### `EffectiveUpstreamLimits`
+| Field | Type | Description |
+| --- | --- | --- |
+| `connect_retry_attempts` | `u32` | Upstream connect retry attempts. |
+| `connect_retry_backoff_ms` | `u64` | Upstream retry backoff delay. |
+| `connect_budget_ms` | `u64` | Total connect wall-clock budget across retries. |
+| `unhealthy_fail_threshold` | `u32` | Consecutive fail threshold for unhealthy marking. |
+| `connect_failfast_hard_errors` | `bool` | Whether hard errors skip additional retries. |
+
+#### `EffectiveMiddleProxyLimits`
+| Field | Type | Description |
+| --- | --- | --- |
+| `floor_mode` | `string` | Effective floor mode (`static` or `adaptive`). |
+| `adaptive_floor_idle_secs` | `u64` | Adaptive floor idle threshold. |
+| `adaptive_floor_min_writers_single_endpoint` | `u8` | Adaptive floor minimum for single-endpoint DCs. |
+| `adaptive_floor_recover_grace_secs` | `u64` | Adaptive floor recovery grace period. |
+| `reconnect_max_concurrent_per_dc` | `u32` | Max concurrent reconnects per DC. |
+| `reconnect_backoff_base_ms` | `u64` | Reconnect base backoff. |
+| `reconnect_backoff_cap_ms` | `u64` | Reconnect backoff cap. |
+| `reconnect_fast_retry_count` | `u32` | Number of fast retries before standard backoff strategy. |
+| `me2dc_fallback` | `bool` | Effective ME -> direct fallback flag. |
+
+#### `EffectiveUserIpPolicyLimits`
+| Field | Type | Description |
+| --- | --- | --- |
+| `mode` | `string` | Unique-IP policy mode (`active_window`, `time_window`, `combined`). |
+| `window_secs` | `u64` | Time window length used by unique-IP policy. |
+
+### `SecurityPostureData`
+| Field | Type | Description |
+| --- | --- | --- |
+| `api_read_only` | `bool` | Current API read-only state. |
+| `api_whitelist_enabled` | `bool` | Whether whitelist filtering is active. |
+| `api_whitelist_entries` | `usize` | Number of configured whitelist CIDRs. |
+| `api_auth_header_enabled` | `bool` | Whether `Authorization` header validation is active. |
+| `proxy_protocol_enabled` | `bool` | Global PROXY protocol accept setting. |
+| `log_level` | `string` | Effective log level (`debug`, `verbose`, `normal`, `silent`). |
+| `telemetry_core_enabled` | `bool` | Core telemetry toggle. |
+| `telemetry_user_enabled` | `bool` | Per-user telemetry toggle. |
+| `telemetry_me_level` | `string` | ME telemetry level (`silent`, `normal`, `debug`). |
+
+### `SecurityWhitelistData`
+| Field | Type | Description |
+| --- | --- | --- |
+| `generated_at_epoch_secs` | `u64` | Snapshot generation timestamp. |
+| `enabled` | `bool` | `true` when whitelist has at least one CIDR entry. |
+| `entries_total` | `usize` | Number of whitelist CIDR entries. |
+| `entries` | `string[]` | Whitelist CIDR entries as strings. |
+
+### Runtime Min Endpoints
+- `/v1/runtime/me_pool_state`: generations, hardswap state, writer contour/health counts, refill inflight snapshot.
+- `/v1/runtime/me_quality`: ME error/drift/reconnect counters and per-DC RTT coverage snapshot.
+- `/v1/runtime/upstream_quality`: upstream runtime policy, connect counters, health summary and per-upstream DC latency/IP preference.
+- `/v1/runtime/nat_stun`: NAT/STUN runtime flags, server lists, reflection cache state and backoff remaining.
+
+### Runtime Edge Endpoints
+- `/v1/runtime/connections/summary`: cached connection totals (`total/me/direct`), active users and top-N users by connections/traffic.
+- `/v1/runtime/events/recent?limit=N`: bounded control-plane ring-buffer events (`limit` clamped to `[1, 1000]`).
+- If `server.api.runtime_edge_enabled=false`, runtime edge endpoints return `enabled=false` with `reason=feature_disabled`.
+
 ### `ZeroAllData`
 | Field | Type | Description |
 | --- | --- | --- |

docs/FAQ.ru.md

@@ -26,6 +26,13 @@ use_middle_proxy = true
 > [!WARNING]
 > У вас не будет отображаться "спонсор прокси" если вы уже подписаны на канал.
 
+**Также вы можете настроить разные каналы для разных пользователей.**
+```toml
+[access.user_ad_tags]
+hello = "ad_tag"
+hello2 = "ad_tag2"
+```
+
 ## Сколько человек может пользоваться 1 ссылкой
 
 По умолчанию 1 ссылкой может пользоваться сколько угодно человек.  

docs/model/MODEL.en.md

@@ -0,0 +1,285 @@
+# Telemt Runtime Model
+
+## Scope
+This document defines runtime concepts used by the Middle-End (ME) transport pipeline and the orchestration logic around it.
+
+It focuses on:
+- `ME Pool / Reader / Writer / Refill / Registry`
+- `Adaptive Floor`
+- `Trio-State`
+- `Generation Lifecycle`
+
+## Core Entities
+
+### ME Pool
+`ME Pool` is the runtime orchestrator for all Middle-End writers.
+
+Responsibilities:
+- Holds writer inventory by DC/family/endpoint.
+- Maintains routing primitives and writer selection policy.
+- Tracks generation state (`active`, `warm`, `draining` context).
+- Applies runtime policies (floor mode, refill, reconnect, reinit, fallback behavior).
+- Exposes readiness gates used by admission logic (for conditional accept/cast behavior).
+
+Non-goals:
+- It does not own client protocol decoding.
+- It does not own per-client business policy (quotas/limits).
+
+### ME Writer
+`ME Writer` is a long-lived ME RPC tunnel bound to one concrete ME endpoint (`ip:port`), with:
+- Outbound command channel (send path).
+- Associated reader loop (inbound path).
+- Health/degraded flags.
+- Contour/state and generation metadata.
+
+A writer is the actual data plane carrier for client sessions once bound.
+
+### ME Reader
+`ME Reader` is the inbound parser/dispatcher for one writer:
+- Reads/decrypts ME RPC frames.
+- Validates sequence/checksum.
+- Routes payloads to client-connection channels via `Registry`.
+- Emits close/ack/data events and updates telemetry.
+
+Design intent:
+- Reader must stay non-blocking as much as possible.
+- Backpressure on a single client route must not stall the whole writer stream.
+
+### Refill
+`Refill` is the recovery mechanism that restores writer coverage when capacity drops:
+- Per-endpoint restore (same endpoint first).
+- Per-DC restore to satisfy required floor.
+- Optional outage-mode/shadow behavior for fragile single-endpoint DCs.
+
+Refill works asynchronously and should not block hot routing paths.
+
+### Registry
+`Registry` is the routing index between ME and client sessions:
+- `conn_id -> client response channel`
+- `conn_id <-> writer_id` binding map
+- writer activity snapshots and idle tracking
+
+Main invariants:
+- A `conn_id` routes to at most one active response channel.
+- Writer loss triggers safe unbind/cleanup and close propagation.
+- Registry state is the source of truth for active ME-bound session mapping.
+
+## Adaptive Floor
+
+### What it is
+`Adaptive Floor` is a runtime policy that changes target writer count per DC based on observed activity, instead of always holding static peak floor.
+
+### Why it exists
+Goals:
+- Reduce idle writer churn under low traffic.
+- Keep enough warm capacity to avoid client-visible stalls on burst recovery.
+- Limit needless reconnect storms on unstable endpoints.
+
+### Behavioral model
+- Under activity: floor converges toward configured static requirement.
+- Under prolonged idle: floor can shrink to a safe minimum.
+- Recovery/grace windows prevent aggressive oscillation.
+
+### Safety constraints
+- Never violate minimal survivability floor for a DC group.
+- Refill must still restore quickly on demand.
+- Floor adaptation must not force-drop already bound healthy sessions.
+
+## Trio-State
+
+`Trio-State` is writer contouring:
+- `Warm`
+- `Active`
+- `Draining`
+
+### State semantics
+- `Warm`: connected and validated, not primary for new binds.
+- `Active`: preferred for new binds and normal traffic.
+- `Draining`: no new regular binds; existing sessions continue until graceful retirement rules apply.
+
+### Transition intent
+- `Warm -> Active`: when coverage/readiness conditions are satisfied.
+- `Active -> Draining`: on generation swap, endpoint replacement, or controlled retirement.
+- `Draining -> removed`: after drain TTL/force-close policy (or when naturally empty).
+
+This separation reduces SPOF and keeps cutovers predictable.
+
+## Generation Lifecycle
+
+Generation isolates pool epochs during reinit/reconfiguration.
+
+### Lifecycle phases
+1. `Bootstrap`: initial writers are established.
+2. `Warmup`: next generation writers are created and validated.
+3. `Activation`: generation promoted to active when coverage gate passes.
+4. `Drain`: previous generation becomes draining, existing sessions are allowed to finish.
+5. `Retire`: old generation writers are removed after graceful rules.
+
+### Operational guarantees
+- No partial generation activation without minimum coverage.
+- Existing healthy client sessions should not be dropped just because a new generation appears.
+- Draining generation exists to absorb in-flight traffic during swap.
+
+### Readiness and admission
+Pool readiness is not equivalent to “all endpoints fully saturated”.
+Typical gating strategy:
+- Open admission when per-DC minimal alive coverage exists.
+- Continue background saturation for multi-endpoint DCs.
+
+This keeps startup latency low while preserving eventual full capacity.
+
+## Interactions Between Concepts
+
+- `Generation` defines pool epochs.
+- `Trio-State` defines per-writer role inside/around those epochs.
+- `Adaptive Floor` defines how much capacity should be maintained right now.
+- `Refill` is the actuator that closes the gap between desired and current capacity.
+- `Registry` keeps per-session routing correctness while all of the above changes over time.
+
+## Architectural Approach
+
+### Layered Design
+The runtime is intentionally split into two planes:
+- `Control Plane`: decides desired topology and policy (`floor`, `generation swap`, `refill`, `fallback`).
+- `Data Plane`: executes packet/session transport (`reader`, `writer`, routing, acks, close propagation).
+
+Architectural rule:
+- Control Plane may change writer inventory and policy.
+- Data Plane must remain stable and low-latency while those changes happen.
+
+### Ownership Model
+Ownership is centered around explicit state domains:
+- `MePool` owns writer lifecycle and policy state.
+- `Registry` owns per-connection routing bindings.
+- `Writer task` owns outbound ME socket send progression.
+- `Reader task` owns inbound ME socket parsing and event dispatch.
+
+This prevents accidental cross-layer mutation and keeps invariants local.
+
+### Control Plane Responsibilities
+Control Plane is event-driven and policy-driven:
+- Startup initialization and readiness gates.
+- Runtime reinit (periodic or config-triggered).
+- Coverage checks per DC/family/endpoint group.
+- Floor enforcement (static/adaptive).
+- Refill scheduling and retry orchestration.
+- Generation transition (`warm -> active`, previous `active -> draining`).
+
+Control Plane must prioritize determinism over short-term aggressiveness.
+
+### Data Plane Responsibilities
+Data Plane is throughput-first and allocation-sensitive:
+- Session bind to writer.
+- Per-frame parsing/validation and dispatch.
+- Ack and close signal propagation.
+- Route drop behavior under missing connection or closed channel.
+- Minimal critical logging in hot path.
+
+Data Plane should avoid waiting on operations that are not strictly required for frame correctness.
+
+## Concurrency and Synchronization
+
+### Concurrency Principles
+- Per-writer isolation: each writer has independent send/read task loops.
+- Per-connection isolation: client channel state is scoped by `conn_id`.
+- Asynchronous recovery: refill/reconnect runs outside the packet hot path.
+
+### Synchronization Strategy
+- Shared maps use fine-grained, short-lived locking.
+- Read-mostly paths avoid broad write-lock windows.
+- Backpressure decisions are localized at route/channel boundary.
+
+Design target:
+- A slow consumer should degrade only itself (or its route), not global writer progress.
+
+### Cancellation and Shutdown
+Writer and reader loops are cancellation-aware:
+- explicit cancel token / close command support;
+- safe unbind and cleanup via registry;
+- deterministic order: stop admission -> drain/close -> release resources.
+
+## Consistency Model
+
+### Session Consistency
+For one `conn_id`:
+- exactly one active route target at a time;
+- close and unbind must be idempotent;
+- writer loss must not leave dangling bindings.
+
+### Generation Consistency
+Generational consistency guarantees:
+- New generation is not promoted before minimum coverage gate.
+- Previous generation remains available in `draining` state during handover.
+- Forced retirement is policy-bound (`drain ttl`, optional force-close), not immediate.
+
+### Policy Consistency
+Policy changes (`adaptive/static floor`, fallback mode, retries) should apply without violating established active-session routing invariants.
+
+## Backpressure and Flow Control
+
+### Route-Level Backpressure
+Route channels are bounded by design.
+When pressure increases:
+- short burst absorption is allowed;
+- prolonged congestion triggers controlled drop semantics;
+- drop accounting is explicit via metrics/counters.
+
+### Reader Non-Blocking Priority
+Inbound ME reader path should never be serialized behind one congested client route.
+Practical implication:
+- prefer non-blocking route attempt in the parser loop;
+- move heavy recovery to async side paths.
+
+## Failure Domain Strategy
+
+### Endpoint-Level Failure
+Failure of one endpoint should trigger endpoint-scoped recovery first:
+- same endpoint reconnect;
+- endpoint replacement within same DC group if applicable.
+
+### DC-Level Degradation
+If a DC group cannot satisfy floor:
+- keep service via remaining coverage if policy allows;
+- continue asynchronous refill saturation in background.
+
+### Whole-Pool Readiness Loss
+If no sufficient ME coverage exists:
+- admission gate can hold new accepts (conditional policy);
+- existing sessions should continue when their path remains healthy.
+
+## Performance Architecture Notes
+
+### Hotpath Discipline
+Allowed in hotpath:
+- fixed-size parsing and cheap validation;
+- bounded channel operations;
+- precomputed or low-allocation access patterns.
+
+Avoid in hotpath:
+- repeated expensive decoding;
+- broad locks with awaits inside critical sections;
+- verbose high-frequency logging.
+
+### Throughput Stability Over Peak Spikes
+Architecture prefers stable throughput and predictable latency over short peak gains that increase churn or long-tail reconnect times.
+
+## Evolution and Extension Rules
+
+To evolve this model safely:
+- Add new policy knobs in Control Plane first.
+- Keep Data Plane contracts stable (`conn_id`, route semantics, close semantics).
+- Validate generation and registry invariants before enabling by default.
+- Introduce new retry/recovery strategies behind explicit config.
+
+## Failure and Recovery Notes
+
+- Single-endpoint DC failure is a normal degraded mode case; policy should prioritize fast reconnect and optional shadow/probing strategies.
+- Idle close by peer should be treated as expected when upstream enforces idle timeout.
+- Reconnect backoff must protect against synchronized churn while still allowing fast first retries.
+- Fallback (`ME -> direct DC`) is a policy switch, not a transport bug by itself.
+
+## Terminology Summary
+- `Coverage`: enough live writers to satisfy per-DC acceptance policy.
+- `Floor`: target minimum writer count policy.
+- `Churn`: frequent writer reconnect/remove cycles.
+- `Hotpath`: per-packet/per-connection data path where extra waits/allocations are expensive.

docs/model/MODEL.ru.md

@@ -0,0 +1,285 @@
+# Runtime-модель Telemt
+
+## Область описания
+Документ фиксирует ключевые runtime-понятия пайплайна Middle-End (ME) и оркестрации вокруг него.
+
+Фокус:
+- `ME Pool / Reader / Writer / Refill / Registry`
+- `Adaptive Floor`
+- `Trio-State`
+- `Generation Lifecycle`
+
+## Базовые сущности
+
+### ME Pool
+`ME Pool` — центральный оркестратор всех Middle-End writer-ов.
+
+Зона ответственности:
+- хранит инвентарь writer-ов по DC/family/endpoint;
+- управляет выбором writer-а и маршрутизацией;
+- ведёт состояние поколений (`active`, `warm`, `draining` контекст);
+- применяет runtime-политики (floor, refill, reconnect, reinit, fallback);
+- отдаёт сигналы готовности для admission-логики (conditional accept/cast).
+
+Что не делает:
+- не декодирует клиентский протокол;
+- не реализует бизнес-политику пользователя (квоты/лимиты).
+
+### ME Writer
+`ME Writer` — долгоживущий ME RPC-канал к конкретному endpoint (`ip:port`), у которого есть:
+- канал команд на отправку;
+- связанный reader loop для входящего потока;
+- флаги состояния/деградации;
+- метаданные contour/state и generation.
+
+Writer — это фактический data-plane носитель клиентских сессий после бинда.
+
+### ME Reader
+`ME Reader` — входной parser/dispatcher одного writer-а:
+- читает и расшифровывает ME RPC-фреймы;
+- проверяет sequence/checksum;
+- маршрутизирует payload в client-каналы через `Registry`;
+- обрабатывает close/ack/data и обновляет телеметрию.
+
+Инженерный принцип:
+- Reader должен оставаться неблокирующим.
+- Backpressure одной клиентской сессии не должен останавливать весь поток writer-а.
+
+### Refill
+`Refill` — механизм восстановления покрытия writer-ов при просадке:
+- восстановление на том же endpoint в первую очередь;
+- восстановление по DC до требуемого floor;
+- опциональные outage/shadow-режимы для хрупких single-endpoint DC.
+
+Refill работает асинхронно и не должен блокировать hotpath.
+
+### Registry
+`Registry` — маршрутизационный индекс между ME и клиентскими сессиями:
+- `conn_id -> канал ответа клиенту`;
+- map биндов `conn_id <-> writer_id`;
+- снимки активности writer-ов и idle-трекинг.
+
+Ключевые инварианты:
+- один `conn_id` маршрутизируется максимум в один активный канал ответа;
+- потеря writer-а приводит к безопасному unbind/cleanup и отправке close;
+- именно `Registry` является источником истины по активным ME-биндам.
+
+## Adaptive Floor
+
+### Что это
+`Adaptive Floor` — runtime-политика, которая динамически меняет целевое число writer-ов на DC в зависимости от активности, а не держит всегда фиксированный статический floor.
+
+### Зачем
+Цели:
+- уменьшить churn на idle-трафике;
+- сохранить достаточную прогретую ёмкость для быстрых всплесков;
+- снизить лишние reconnect-штормы на нестабильных endpoint.
+
+### Модель поведения
+- при активности floor стремится к статическому требованию;
+- при длительном idle floor может снижаться до безопасного минимума;
+- grace/recovery окна не дают системе "флапать" слишком резко.
+
+### Ограничения безопасности
+- нельзя нарушать минимальный floor выживаемости DC-группы;
+- refill обязан быстро нарастить покрытие по запросу;
+- адаптация не должна принудительно ронять уже привязанные healthy-сессии.
+
+## Trio-State
+
+`Trio-State` — контурная роль writer-а:
+- `Warm`
+- `Active`
+- `Draining`
+
+### Семантика состояний
+- `Warm`: writer подключён и валиден, но не основной для новых биндов.
+- `Active`: приоритетный для новых биндов и обычного трафика.
+- `Draining`: новые обычные бинды не назначаются; текущие сессии живут до правил graceful-вывода.
+
+### Логика переходов
+- `Warm -> Active`: когда достигнуты условия покрытия/готовности.
+- `Active -> Draining`: при swap поколения, замене endpoint или контролируемом выводе.
+- `Draining -> removed`: после drain TTL/force-close политики (или естественного опустошения).
+
+Такое разделение снижает SPOF-риски и делает cutover предсказуемым.
+
+## Generation Lifecycle
+
+Generation изолирует эпохи пула при reinit/reconfiguration.
+
+### Фазы жизненного цикла
+1. `Bootstrap`: поднимается начальный набор writer-ов.
+2. `Warmup`: создаётся и валидируется новое поколение.
+3. `Activation`: новое поколение становится active после прохождения coverage-gate.
+4. `Drain`: предыдущее поколение переводится в draining, текущим сессиям дают завершиться.
+5. `Retire`: старое поколение удаляется по graceful-правилам.
+
+### Операционные гарантии
+- нельзя активировать поколение частично без минимального покрытия;
+- healthy-клиенты не должны теряться только из-за появления нового поколения;
+- draining-поколение служит буфером для in-flight трафика во время swap.
+
+### Готовность и приём клиентов
+Готовность пула не равна "все endpoint полностью насыщены".
+Типичная стратегия:
+- открыть admission при минимально достаточном alive-покрытии по DC;
+- параллельно продолжать saturation для multi-endpoint DC.
+
+Это уменьшает startup latency и сохраняет выход на полную ёмкость.
+
+## Как понятия связаны между собой
+
+- `Generation` задаёт эпохи пула.
+- `Trio-State` задаёт роль каждого writer-а внутри/между эпохами.
+- `Adaptive Floor` задаёт, сколько ёмкости нужно сейчас.
+- `Refill` — исполнитель, который закрывает разницу между desired и current capacity.
+- `Registry` гарантирует корректную маршрутизацию сессий, пока всё выше меняется.
+
+## Архитектурный подход
+
+### Слоистая модель
+Runtime специально разделён на две плоскости:
+- `Control Plane`: принимает решения о целевой топологии и политиках (`floor`, `generation swap`, `refill`, `fallback`).
+- `Data Plane`: исполняет транспорт сессий и пакетов (`reader`, `writer`, маршрутизация, ack, close).
+
+Ключевое правило:
+- Control Plane может менять состав writer-ов и policy.
+- Data Plane должен оставаться стабильным и низколатентным в момент этих изменений.
+
+### Модель владения состоянием
+Владение разделено по доменам:
+- `MePool` владеет жизненным циклом writer-ов и policy-state.
+- `Registry` владеет routing-биндами клиентских сессий.
+- `Writer task` владеет исходящей прогрессией ME-сокета.
+- `Reader task` владеет входящим парсингом и dispatch-событиями.
+
+Это ограничивает побочные мутации и локализует инварианты.
+
+### Обязанности Control Plane
+Control Plane работает событийно и policy-ориентированно:
+- стартовая инициализация и readiness-gate;
+- runtime reinit (периодический и/или по изменению конфигурации);
+- проверки покрытия по DC/family/endpoint group;
+- применение floor-политики (static/adaptive);
+- планирование refill и orchestration retry;
+- переходы поколений (`warm -> active`, прежний `active -> draining`).
+
+Для него важнее детерминизм, чем агрессивная краткосрочная реакция.
+
+### Обязанности Data Plane
+Data Plane ориентирован на пропускную способность и предсказуемую задержку:
+- bind клиентской сессии к writer-у;
+- per-frame parsing/validation/dispatch;
+- распространение ack/close;
+- корректная реакция на missing conn/closed channel;
+- минимальный лог-шум в hotpath.
+
+Data Plane не должен ждать операций, не критичных для корректности текущего фрейма.
+
+## Конкурентность и синхронизация
+
+### Принципы конкурентности
+- Изоляция по writer-у: у каждого writer-а независимые send/read loop.
+- Изоляция по сессии: состояние канала локально для `conn_id`.
+- Асинхронное восстановление: refill/reconnect выполняются вне пакетного hotpath.
+
+### Стратегия синхронизации
+- Для shared map используются короткие и узкие lock-секции.
+- Read-heavy пути избегают длительных write-lock окон.
+- Решения по backpressure локализованы на границе route/channel.
+
+Цель:
+- медленный consumer должен деградировать локально, не останавливая глобальный прогресс writer-а.
+
+### Cancellation и shutdown
+Reader/Writer loop должны быть cancellation-aware:
+- явные cancel token / close command;
+- безопасный unbind/cleanup через registry;
+- детерминированный порядок: stop admission -> drain/close -> release resources.
+
+## Модель согласованности
+
+### Согласованность сессии
+Для одного `conn_id`:
+- одновременно ровно один активный route-target;
+- close/unbind операции идемпотентны;
+- потеря writer-а не оставляет dangling-бинды.
+
+### Согласованность поколения
+Гарантии generation:
+- новое поколение не активируется до прохождения минимального coverage-gate;
+- предыдущее поколение остаётся в `draining` на время handover;
+- принудительный вывод writer-ов ограничен policy (`drain ttl`, optional force-close), а не мгновенный.
+
+### Согласованность политик
+Изменение policy (`adaptive/static floor`, fallback mode, retries) не должно ломать инварианты маршрутизации уже активных сессий.
+
+## Backpressure и управление потоком
+
+### Route-level backpressure
+Route-каналы намеренно bounded.
+При росте нагрузки:
+- кратковременный burst поглощается;
+- длительная перегрузка переходит в контролируемую drop-семантику;
+- все drop-сценарии должны быть прозрачно видны в метриках.
+
+### Приоритет неблокирующего Reader
+Входящий ME-reader path не должен сериализоваться из-за одной перегруженной клиентской сессии.
+Практически это означает:
+- использовать неблокирующую попытку route в parser loop;
+- выносить тяжёлое восстановление в асинхронные side-path.
+
+## Стратегия доменов отказа
+
+### Отказ отдельного endpoint
+Сначала применяется endpoint-local recovery:
+- reconnect в тот же endpoint;
+- затем замена endpoint внутри той же DC-группы (если доступно).
+
+### Деградация уровня DC
+Если DC-группа не набирает floor:
+- сервис сохраняется на остаточном покрытии (если policy разрешает);
+- saturation refill продолжается асинхронно в фоне.
+
+### Потеря готовности всего пула
+Если достаточного ME-покрытия нет:
+- admission gate может временно закрыть приём новых подключений (conditional policy);
+- уже активные сессии продолжают работать, пока их маршрут остаётся healthy.
+
+## Архитектурные заметки по производительности
+
+### Дисциплина hotpath
+Допустимо в hotpath:
+- фиксированный и дешёвый parsing/validation;
+- bounded channel operations;
+- precomputed/low-allocation доступ к данным.
+
+Нежелательно в hotpath:
+- повторные дорогие decode;
+- широкие lock-секции с `await` внутри;
+- высокочастотный подробный logging.
+
+### Стабильность важнее пиков
+Архитектура приоритетно выбирает стабильную пропускную способность и предсказуемую latency, а не краткосрочные пики ценой churn и long-tail reconnect.
+
+## Правила эволюции модели
+
+Чтобы расширять модель безопасно:
+- новые policy knobs сначала внедрять в Control Plane;
+- контракты Data Plane (`conn_id`, route/close семантика) держать стабильными;
+- перед дефолтным включением проверять generation/registry инварианты;
+- новые recovery/retry стратегии вводить через явный config-флаг.
+
+## Нюансы отказов и восстановления
+
+- падение single-endpoint DC — штатный деградированный сценарий; приоритет: быстрый reconnect и, при необходимости, shadow/probing;
+- idle-close со стороны peer должен считаться нормальным событием при upstream idle-timeout;
+- backoff reconnect-логики должен ограничивать синхронный churn, но сохранять быстрые первые попытки;
+- fallback (`ME -> direct DC`) — это переключаемая policy-ветка, а не автоматический признак бага транспорта.
+
+## Краткий словарь
+- `Coverage`: достаточное число живых writer-ов для политики приёма по DC.
+- `Floor`: целевая минимальная ёмкость writer-ов.
+- `Churn`: частые циклы reconnect/remove writer-ов.
+- `Hotpath`: пер-пакетный/пер-коннектный путь, где любые лишние ожидания и аллокации особенно дороги.

src/api/events.rs

@@ -0,0 +1,90 @@
+use std::collections::VecDeque;
+use std::sync::Mutex;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use serde::Serialize;
+
+#[derive(Clone, Serialize)]
+pub(super) struct ApiEventRecord {
+    pub(super) seq: u64,
+    pub(super) ts_epoch_secs: u64,
+    pub(super) event_type: String,
+    pub(super) context: String,
+}
+
+#[derive(Clone, Serialize)]
+pub(super) struct ApiEventSnapshot {
+    pub(super) capacity: usize,
+    pub(super) dropped_total: u64,
+    pub(super) events: Vec<ApiEventRecord>,
+}
+
+struct ApiEventsInner {
+    capacity: usize,
+    dropped_total: u64,
+    next_seq: u64,
+    events: VecDeque<ApiEventRecord>,
+}
+
+/// Bounded ring-buffer for control-plane API/runtime events.
+pub(crate) struct ApiEventStore {
+    inner: Mutex<ApiEventsInner>,
+}
+
+impl ApiEventStore {
+    pub(super) fn new(capacity: usize) -> Self {
+        let bounded = capacity.max(16);
+        Self {
+            inner: Mutex::new(ApiEventsInner {
+                capacity: bounded,
+                dropped_total: 0,
+                next_seq: 1,
+                events: VecDeque::with_capacity(bounded),
+            }),
+        }
+    }
+
+    pub(super) fn record(&self, event_type: &str, context: impl Into<String>) {
+        let now_epoch_secs = SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .unwrap_or_default()
+            .as_secs();
+        let mut context = context.into();
+        if context.len() > 256 {
+            context.truncate(256);
+        }
+
+        let mut guard = self.inner.lock().expect("api event store mutex poisoned");
+        if guard.events.len() == guard.capacity {
+            guard.events.pop_front();
+            guard.dropped_total = guard.dropped_total.saturating_add(1);
+        }
+        let seq = guard.next_seq;
+        guard.next_seq = guard.next_seq.saturating_add(1);
+        guard.events.push_back(ApiEventRecord {
+            seq,
+            ts_epoch_secs: now_epoch_secs,
+            event_type: event_type.to_string(),
+            context,
+        });
+    }
+
+    pub(super) fn snapshot(&self, limit: usize) -> ApiEventSnapshot {
+        let guard = self.inner.lock().expect("api event store mutex poisoned");
+        let bounded_limit = limit.clamp(1, guard.capacity.max(1));
+        let mut items: Vec<ApiEventRecord> = guard
+            .events
+            .iter()
+            .rev()
+            .take(bounded_limit)
+            .cloned()
+            .collect();
+        items.reverse();
+
+        ApiEventSnapshot {
+            capacity: guard.capacity,
+            dropped_total: guard.dropped_total,
+            events: items,
+        }
+    }
+}

src/api/http_utils.rs

@@ -0,0 +1,91 @@
+use http_body_util::{BodyExt, Full};
+use hyper::StatusCode;
+use hyper::body::{Bytes, Incoming};
+use serde::Serialize;
+use serde::de::DeserializeOwned;
+
+use super::model::{ApiFailure, ErrorBody, ErrorResponse, SuccessResponse};
+
+pub(super) fn success_response<T: Serialize>(
+    status: StatusCode,
+    data: T,
+    revision: String,
+) -> hyper::Response<Full<Bytes>> {
+    let payload = SuccessResponse {
+        ok: true,
+        data,
+        revision,
+    };
+    let body = serde_json::to_vec(&payload).unwrap_or_else(|_| b"{\"ok\":false}".to_vec());
+    hyper::Response::builder()
+        .status(status)
+        .header("content-type", "application/json; charset=utf-8")
+        .body(Full::new(Bytes::from(body)))
+        .unwrap()
+}
+
+pub(super) fn error_response(
+    request_id: u64,
+    failure: ApiFailure,
+) -> hyper::Response<Full<Bytes>> {
+    let payload = ErrorResponse {
+        ok: false,
+        error: ErrorBody {
+            code: failure.code,
+            message: failure.message,
+        },
+        request_id,
+    };
+    let body = serde_json::to_vec(&payload).unwrap_or_else(|_| {
+        format!(
+            "{{\"ok\":false,\"error\":{{\"code\":\"internal_error\",\"message\":\"serialization failed\"}},\"request_id\":{}}}",
+            request_id
+        )
+        .into_bytes()
+    });
+    hyper::Response::builder()
+        .status(failure.status)
+        .header("content-type", "application/json; charset=utf-8")
+        .body(Full::new(Bytes::from(body)))
+        .unwrap()
+}
+
+pub(super) async fn read_json<T: DeserializeOwned>(
+    body: Incoming,
+    limit: usize,
+) -> Result<T, ApiFailure> {
+    let bytes = read_body_with_limit(body, limit).await?;
+    serde_json::from_slice(&bytes).map_err(|_| ApiFailure::bad_request("Invalid JSON body"))
+}
+
+pub(super) async fn read_optional_json<T: DeserializeOwned>(
+    body: Incoming,
+    limit: usize,
+) -> Result<Option<T>, ApiFailure> {
+    let bytes = read_body_with_limit(body, limit).await?;
+    if bytes.is_empty() {
+        return Ok(None);
+    }
+    serde_json::from_slice(&bytes)
+        .map(Some)
+        .map_err(|_| ApiFailure::bad_request("Invalid JSON body"))
+}
+
+async fn read_body_with_limit(body: Incoming, limit: usize) -> Result<Vec<u8>, ApiFailure> {
+    let mut collected = Vec::new();
+    let mut body = body;
+    while let Some(frame_result) = body.frame().await {
+        let frame = frame_result.map_err(|_| ApiFailure::bad_request("Invalid request body"))?;
+        if let Some(chunk) = frame.data_ref() {
+            if collected.len().saturating_add(chunk.len()) > limit {
+                return Err(ApiFailure::new(
+                    StatusCode::PAYLOAD_TOO_LARGE,
+                    "payload_too_large",
+                    format!("Body exceeds {} bytes", limit),
+                ));
+            }
+            collected.extend_from_slice(chunk);
+        }
+    }
+    Ok(collected)
+}

src/api/mod.rs

@@ -2,16 +2,14 @@ use std::convert::Infallible;
 use std::net::{IpAddr, SocketAddr};
 use std::path::PathBuf;
 use std::sync::Arc;
-use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
 
-use http_body_util::{BodyExt, Full};
+use http_body_util::Full;
 use hyper::body::{Bytes, Incoming};
 use hyper::header::AUTHORIZATION;
 use hyper::server::conn::http1;
 use hyper::service::service_fn;
 use hyper::{Method, Request, Response, StatusCode};
-use serde::Serialize;
-use serde::de::DeserializeOwned;
 use tokio::net::TcpListener;
 use tokio::sync::{Mutex, watch};
 use tracing::{debug, info, warn};
@@ -23,21 +21,48 @@ use crate::transport::middle_proxy::MePool;
 use crate::transport::UpstreamManager;
 
 mod config_store;
+mod events;
+mod http_utils;
 mod model;
+mod runtime_edge;
+mod runtime_min;
 mod runtime_stats;
+mod runtime_watch;
+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 model::{
-    ApiFailure, CreateUserRequest, ErrorBody, ErrorResponse, HealthData, PatchUserRequest,
+    ApiFailure, CreateUserRequest, HealthData, PatchUserRequest, RotateSecretRequest, SummaryData,
-    RotateSecretRequest, SuccessResponse, SummaryData,
+};
+use runtime_edge::{
+    EdgeConnectionsCacheEntry, build_runtime_connections_summary_data,
+    build_runtime_events_recent_data,
+};
+use runtime_min::{
+    build_runtime_me_pool_state_data, build_runtime_me_quality_data, build_runtime_nat_stun_data,
+    build_runtime_upstream_quality_data, build_security_whitelist_data,
 };
 use runtime_stats::{
     MinimalCacheEntry, build_dcs_data, build_me_writers_data, build_minimal_all_data,
     build_upstreams_data, build_zero_all_data,
 };
+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 {
+    pub(super) process_started_at_epoch_secs: u64,
+    pub(super) config_reload_count: AtomicU64,
+    pub(super) last_config_reload_epoch_secs: AtomicU64,
+    pub(super) admission_open: AtomicBool,
+}
+
 #[derive(Clone)]
 pub(super) struct ApiShared {
     pub(super) stats: Arc<Stats>,
@@ -49,7 +74,11 @@ pub(super) struct ApiShared {
     pub(super) startup_detected_ip_v6: Option<IpAddr>,
     pub(super) mutation_lock: Arc<Mutex<()>>,
     pub(super) minimal_cache: Arc<Mutex<Option<MinimalCacheEntry>>>,
+    pub(super) runtime_edge_connections_cache: Arc<Mutex<Option<EdgeConnectionsCacheEntry>>>,
+    pub(super) runtime_edge_recompute_lock: Arc<Mutex<()>>,
+    pub(super) runtime_events: Arc<ApiEventStore>,
     pub(super) request_id: Arc<AtomicU64>,
+    pub(super) runtime_state: Arc<ApiRuntimeState>,
 }
 
 impl ApiShared {
@@ -65,9 +94,11 @@ pub async fn serve(
     me_pool: Option<Arc<MePool>>,
     upstream_manager: Arc<UpstreamManager>,
     config_rx: watch::Receiver<Arc<ProxyConfig>>,
+    admission_rx: watch::Receiver<bool>,
     config_path: PathBuf,
     startup_detected_ip_v4: Option<IpAddr>,
     startup_detected_ip_v6: Option<IpAddr>,
+    process_started_at_epoch_secs: u64,
 ) {
     let listener = match TcpListener::bind(listen).await {
         Ok(listener) => listener,
@@ -83,6 +114,13 @@ pub async fn serve(
 
     info!("API endpoint: http://{}/v1/*", listen);
 
+    let runtime_state = Arc::new(ApiRuntimeState {
+        process_started_at_epoch_secs,
+        config_reload_count: AtomicU64::new(0),
+        last_config_reload_epoch_secs: AtomicU64::new(0),
+        admission_open: AtomicBool::new(*admission_rx.borrow()),
+    });
+
     let shared = Arc::new(ApiShared {
         stats,
         ip_tracker,
@@ -93,9 +131,22 @@ pub async fn serve(
         startup_detected_ip_v6,
         mutation_lock: Arc::new(Mutex::new(())),
         minimal_cache: Arc::new(Mutex::new(None)),
+        runtime_edge_connections_cache: Arc::new(Mutex::new(None)),
+        runtime_edge_recompute_lock: Arc::new(Mutex::new(())),
+        runtime_events: Arc::new(ApiEventStore::new(
+            config_rx.borrow().server.api.runtime_edge_events_capacity,
+        )),
         request_id: Arc::new(AtomicU64::new(1)),
+        runtime_state: runtime_state.clone(),
     });
 
+    spawn_runtime_watchers(
+        config_rx.clone(),
+        admission_rx.clone(),
+        runtime_state.clone(),
+        shared.runtime_events.clone(),
+    );
+
     loop {
         let (stream, peer) = match listener.accept().await {
             Ok(v) => v,
@@ -177,6 +228,7 @@ async fn handle(
 
     let method = req.method().clone();
     let path = req.uri().path().to_string();
+    let query = req.uri().query().map(str::to_string);
     let body_limit = api_cfg.request_body_limit_bytes;
 
     let result: Result<Response<Full<Bytes>>, ApiFailure> = async {
@@ -189,6 +241,31 @@ async fn handle(
                 };
                 Ok(success_response(StatusCode::OK, data, revision))
             }
+            ("GET", "/v1/system/info") => {
+                let revision = current_revision(&shared.config_path).await?;
+                let data = build_system_info_data(shared.as_ref(), cfg.as_ref(), &revision);
+                Ok(success_response(StatusCode::OK, data, revision))
+            }
+            ("GET", "/v1/runtime/gates") => {
+                let revision = current_revision(&shared.config_path).await?;
+                let data = build_runtime_gates_data(shared.as_ref(), cfg.as_ref());
+                Ok(success_response(StatusCode::OK, data, revision))
+            }
+            ("GET", "/v1/limits/effective") => {
+                let revision = current_revision(&shared.config_path).await?;
+                let data = build_limits_effective_data(cfg.as_ref());
+                Ok(success_response(StatusCode::OK, data, revision))
+            }
+            ("GET", "/v1/security/posture") => {
+                let revision = current_revision(&shared.config_path).await?;
+                let data = build_security_posture_data(cfg.as_ref());
+                Ok(success_response(StatusCode::OK, data, revision))
+            }
+            ("GET", "/v1/security/whitelist") => {
+                let revision = current_revision(&shared.config_path).await?;
+                let data = build_security_whitelist_data(cfg.as_ref());
+                Ok(success_response(StatusCode::OK, data, revision))
+            }
             ("GET", "/v1/stats/summary") => {
                 let revision = current_revision(&shared.config_path).await?;
                 let data = SummaryData {
@@ -225,6 +302,40 @@ async fn handle(
                 let data = build_dcs_data(shared.as_ref(), api_cfg).await;
                 Ok(success_response(StatusCode::OK, data, revision))
             }
+            ("GET", "/v1/runtime/me_pool_state") => {
+                let revision = current_revision(&shared.config_path).await?;
+                let data = build_runtime_me_pool_state_data(shared.as_ref()).await;
+                Ok(success_response(StatusCode::OK, data, revision))
+            }
+            ("GET", "/v1/runtime/me_quality") => {
+                let revision = current_revision(&shared.config_path).await?;
+                let data = build_runtime_me_quality_data(shared.as_ref()).await;
+                Ok(success_response(StatusCode::OK, data, revision))
+            }
+            ("GET", "/v1/runtime/upstream_quality") => {
+                let revision = current_revision(&shared.config_path).await?;
+                let data = build_runtime_upstream_quality_data(shared.as_ref()).await;
+                Ok(success_response(StatusCode::OK, data, revision))
+            }
+            ("GET", "/v1/runtime/nat_stun") => {
+                let revision = current_revision(&shared.config_path).await?;
+                let data = build_runtime_nat_stun_data(shared.as_ref()).await;
+                Ok(success_response(StatusCode::OK, data, revision))
+            }
+            ("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;
+                Ok(success_response(StatusCode::OK, data, revision))
+            }
+            ("GET", "/v1/runtime/events/recent") => {
+                let revision = current_revision(&shared.config_path).await?;
+                let data = build_runtime_events_recent_data(
+                    shared.as_ref(),
+                    cfg.as_ref(),
+                    query.as_deref(),
+                );
+                Ok(success_response(StatusCode::OK, data, revision))
+            }
             ("GET", "/v1/stats/users") | ("GET", "/v1/users") => {
                 let revision = current_revision(&shared.config_path).await?;
                 let users = users_from_config(
@@ -250,7 +361,17 @@ async fn handle(
                 }
                 let expected_revision = parse_if_match(req.headers());
                 let body = read_json::<CreateUserRequest>(req.into_body(), body_limit).await?;
-                let (data, revision) = create_user(body, expected_revision, &shared).await?;
+                let result = create_user(body, expected_revision, &shared).await;
+                let (data, revision) = match result {
+                    Ok(ok) => ok,
+                    Err(error) => {
+                        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));
                 Ok(success_response(StatusCode::CREATED, data, revision))
             }
             _ => {
@@ -290,8 +411,20 @@ async fn handle(
                         }
                         let expected_revision = parse_if_match(req.headers());
                         let body = read_json::<PatchUserRequest>(req.into_body(), body_limit).await?;
-                        let (data, revision) =
+                        let result = patch_user(user, body, expected_revision, &shared).await;
-                            patch_user(user, body, expected_revision, &shared).await?;
+                        let (data, revision) = match result {
+                            Ok(ok) => ok,
+                            Err(error) => {
+                                shared.runtime_events.record(
+                                    "api.user.patch.failed",
+                                    format!("username={} code={}", user, error.code),
+                                );
+                                return Err(error);
+                            }
+                        };
+                        shared
+                            .runtime_events
+                            .record("api.user.patch.ok", format!("username={}", data.username));
                         return Ok(success_response(StatusCode::OK, data, revision));
                     }
                     if method == Method::DELETE {
@@ -306,8 +439,21 @@ async fn handle(
                             ));
                         }
                         let expected_revision = parse_if_match(req.headers());
-                        let (deleted_user, revision) =
+                        let result = delete_user(user, expected_revision, &shared).await;
-                            delete_user(user, expected_revision, &shared).await?;
+                        let (deleted_user, revision) = match result {
+                            Ok(ok) => ok,
+                            Err(error) => {
+                                shared.runtime_events.record(
+                                    "api.user.delete.failed",
+                                    format!("username={} code={}", user, error.code),
+                                );
+                                return Err(error);
+                            }
+                        };
+                        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
@@ -329,9 +475,27 @@ async fn handle(
                         let body =
                             read_optional_json::<RotateSecretRequest>(req.into_body(), body_limit)
                                 .await?;
-                        let (data, revision) =
+                        let result = rotate_secret(
-                            rotate_secret(base_user, body.unwrap_or_default(), expected_revision, &shared)
+                            base_user,
-                                .await?;
+                            body.unwrap_or_default(),
+                            expected_revision,
+                            &shared,
+                        )
+                        .await;
+                        let (data, revision) = match result {
+                            Ok(ok) => ok,
+                            Err(error) => {
+                                shared.runtime_events.record(
+                                    "api.user.rotate_secret.failed",
+                                    format!("username={} code={}", base_user, error.code),
+                                );
+                                return Err(error);
+                            }
+                        };
+                        shared.runtime_events.record(
+                            "api.user.rotate_secret.ok",
+                            format!("username={}", base_user),
+                        );
                         return Ok(success_response(StatusCode::OK, data, revision));
                     }
                     if method == Method::POST {
@@ -363,81 +527,3 @@ async fn handle(
         Err(error) => Ok(error_response(request_id, error)),
     }
 }
-
-fn success_response<T: Serialize>(
-    status: StatusCode,
-    data: T,
-    revision: String,
-) -> Response<Full<Bytes>> {
-    let payload = SuccessResponse {
-        ok: true,
-        data,
-        revision,
-    };
-    let body = serde_json::to_vec(&payload).unwrap_or_else(|_| b"{\"ok\":false}".to_vec());
-    Response::builder()
-        .status(status)
-        .header("content-type", "application/json; charset=utf-8")
-        .body(Full::new(Bytes::from(body)))
-        .unwrap()
-}
-
-fn error_response(request_id: u64, failure: ApiFailure) -> Response<Full<Bytes>> {
-    let payload = ErrorResponse {
-        ok: false,
-        error: ErrorBody {
-            code: failure.code,
-            message: failure.message,
-        },
-        request_id,
-    };
-    let body = serde_json::to_vec(&payload).unwrap_or_else(|_| {
-        format!(
-            "{{\"ok\":false,\"error\":{{\"code\":\"internal_error\",\"message\":\"serialization failed\"}},\"request_id\":{}}}",
-            request_id
-        )
-        .into_bytes()
-    });
-    Response::builder()
-        .status(failure.status)
-        .header("content-type", "application/json; charset=utf-8")
-        .body(Full::new(Bytes::from(body)))
-        .unwrap()
-}
-
-async fn read_json<T: DeserializeOwned>(body: Incoming, limit: usize) -> Result<T, ApiFailure> {
-    let bytes = read_body_with_limit(body, limit).await?;
-    serde_json::from_slice(&bytes).map_err(|_| ApiFailure::bad_request("Invalid JSON body"))
-}
-
-async fn read_optional_json<T: DeserializeOwned>(
-    body: Incoming,
-    limit: usize,
-) -> Result<Option<T>, ApiFailure> {
-    let bytes = read_body_with_limit(body, limit).await?;
-    if bytes.is_empty() {
-        return Ok(None);
-    }
-    serde_json::from_slice(&bytes)
-        .map(Some)
-        .map_err(|_| ApiFailure::bad_request("Invalid JSON body"))
-}
-
-async fn read_body_with_limit(body: Incoming, limit: usize) -> Result<Vec<u8>, ApiFailure> {
-    let mut collected = Vec::new();
-    let mut body = body;
-    while let Some(frame_result) = body.frame().await {
-        let frame = frame_result.map_err(|_| ApiFailure::bad_request("Invalid request body"))?;
-        if let Some(chunk) = frame.data_ref() {
-            if collected.len().saturating_add(chunk.len()) > limit {
-                return Err(ApiFailure::new(
-                    StatusCode::PAYLOAD_TOO_LARGE,
-                    "payload_too_large",
-                    format!("Body exceeds {} bytes", limit),
-                ));
-            }
-            collected.extend_from_slice(chunk);
-        }
-    }
-    Ok(collected)
-}

src/api/runtime_edge.rs

@@ -0,0 +1,294 @@
+use std::cmp::Reverse;
+use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
+
+use serde::Serialize;
+
+use crate::config::ProxyConfig;
+
+use super::ApiShared;
+use super::events::ApiEventRecord;
+
+const FEATURE_DISABLED_REASON: &str = "feature_disabled";
+const SOURCE_UNAVAILABLE_REASON: &str = "source_unavailable";
+const EVENTS_DEFAULT_LIMIT: usize = 50;
+const EVENTS_MAX_LIMIT: usize = 1000;
+
+#[derive(Clone, Serialize)]
+pub(super) struct RuntimeEdgeConnectionUserData {
+    pub(super) username: String,
+    pub(super) current_connections: u64,
+    pub(super) total_octets: u64,
+}
+
+#[derive(Clone, Serialize)]
+pub(super) struct RuntimeEdgeConnectionTotalsData {
+    pub(super) current_connections: u64,
+    pub(super) current_connections_me: u64,
+    pub(super) current_connections_direct: u64,
+    pub(super) active_users: usize,
+}
+
+#[derive(Clone, Serialize)]
+pub(super) struct RuntimeEdgeConnectionTopData {
+    pub(super) limit: usize,
+    pub(super) by_connections: Vec<RuntimeEdgeConnectionUserData>,
+    pub(super) by_throughput: Vec<RuntimeEdgeConnectionUserData>,
+}
+
+#[derive(Clone, Serialize)]
+pub(super) struct RuntimeEdgeConnectionCacheData {
+    pub(super) ttl_ms: u64,
+    pub(super) served_from_cache: bool,
+    pub(super) stale_cache_used: bool,
+}
+
+#[derive(Clone, Serialize)]
+pub(super) struct RuntimeEdgeConnectionTelemetryData {
+    pub(super) user_enabled: bool,
+    pub(super) throughput_is_cumulative: bool,
+}
+
+#[derive(Clone, Serialize)]
+pub(super) struct RuntimeEdgeConnectionsSummaryPayload {
+    pub(super) cache: RuntimeEdgeConnectionCacheData,
+    pub(super) totals: RuntimeEdgeConnectionTotalsData,
+    pub(super) top: RuntimeEdgeConnectionTopData,
+    pub(super) telemetry: RuntimeEdgeConnectionTelemetryData,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeEdgeConnectionsSummaryData {
+    pub(super) enabled: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) reason: Option<&'static str>,
+    pub(super) generated_at_epoch_secs: u64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) data: Option<RuntimeEdgeConnectionsSummaryPayload>,
+}
+
+#[derive(Clone)]
+pub(crate) struct EdgeConnectionsCacheEntry {
+    pub(super) expires_at: Instant,
+    pub(super) payload: RuntimeEdgeConnectionsSummaryPayload,
+    pub(super) generated_at_epoch_secs: u64,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeEdgeEventsPayload {
+    pub(super) capacity: usize,
+    pub(super) dropped_total: u64,
+    pub(super) events: Vec<ApiEventRecord>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeEdgeEventsData {
+    pub(super) enabled: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) reason: Option<&'static str>,
+    pub(super) generated_at_epoch_secs: u64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) data: Option<RuntimeEdgeEventsPayload>,
+}
+
+pub(super) async fn build_runtime_connections_summary_data(
+    shared: &ApiShared,
+    cfg: &ProxyConfig,
+) -> RuntimeEdgeConnectionsSummaryData {
+    let now_epoch_secs = now_epoch_secs();
+    let api_cfg = &cfg.server.api;
+    if !api_cfg.runtime_edge_enabled {
+        return RuntimeEdgeConnectionsSummaryData {
+            enabled: false,
+            reason: Some(FEATURE_DISABLED_REASON),
+            generated_at_epoch_secs: now_epoch_secs,
+            data: None,
+        };
+    }
+
+    let (generated_at_epoch_secs, payload) = match get_connections_payload_cached(
+        shared,
+        api_cfg.runtime_edge_cache_ttl_ms,
+        api_cfg.runtime_edge_top_n,
+    )
+    .await
+    {
+        Some(v) => v,
+        None => {
+            return RuntimeEdgeConnectionsSummaryData {
+                enabled: true,
+                reason: Some(SOURCE_UNAVAILABLE_REASON),
+                generated_at_epoch_secs: now_epoch_secs,
+                data: None,
+            };
+        }
+    };
+
+    RuntimeEdgeConnectionsSummaryData {
+        enabled: true,
+        reason: None,
+        generated_at_epoch_secs,
+        data: Some(payload),
+    }
+}
+
+pub(super) fn build_runtime_events_recent_data(
+    shared: &ApiShared,
+    cfg: &ProxyConfig,
+    query: Option<&str>,
+) -> RuntimeEdgeEventsData {
+    let now_epoch_secs = now_epoch_secs();
+    let api_cfg = &cfg.server.api;
+    if !api_cfg.runtime_edge_enabled {
+        return RuntimeEdgeEventsData {
+            enabled: false,
+            reason: Some(FEATURE_DISABLED_REASON),
+            generated_at_epoch_secs: now_epoch_secs,
+            data: None,
+        };
+    }
+
+    let limit = parse_recent_events_limit(query, EVENTS_DEFAULT_LIMIT, EVENTS_MAX_LIMIT);
+    let snapshot = shared.runtime_events.snapshot(limit);
+
+    RuntimeEdgeEventsData {
+        enabled: true,
+        reason: None,
+        generated_at_epoch_secs: now_epoch_secs,
+        data: Some(RuntimeEdgeEventsPayload {
+            capacity: snapshot.capacity,
+            dropped_total: snapshot.dropped_total,
+            events: snapshot.events,
+        }),
+    }
+}
+
+async fn get_connections_payload_cached(
+    shared: &ApiShared,
+    cache_ttl_ms: u64,
+    top_n: usize,
+) -> Option<(u64, RuntimeEdgeConnectionsSummaryPayload)> {
+    if cache_ttl_ms > 0 {
+        let now = Instant::now();
+        let cached = shared.runtime_edge_connections_cache.lock().await.clone();
+        if let Some(entry) = cached
+            && now < entry.expires_at
+        {
+            let mut payload = entry.payload;
+            payload.cache.served_from_cache = true;
+            payload.cache.stale_cache_used = false;
+            return Some((entry.generated_at_epoch_secs, payload));
+        }
+    }
+
+    let Ok(_guard) = shared.runtime_edge_recompute_lock.try_lock() else {
+        let cached = shared.runtime_edge_connections_cache.lock().await.clone();
+        if let Some(entry) = cached {
+            let mut payload = entry.payload;
+            payload.cache.served_from_cache = true;
+            payload.cache.stale_cache_used = true;
+            return Some((entry.generated_at_epoch_secs, payload));
+        }
+        return None;
+    };
+
+    let generated_at_epoch_secs = now_epoch_secs();
+    let payload = recompute_connections_payload(shared, cache_ttl_ms, top_n).await;
+
+    if cache_ttl_ms > 0 {
+        let entry = EdgeConnectionsCacheEntry {
+            expires_at: Instant::now() + Duration::from_millis(cache_ttl_ms),
+            payload: payload.clone(),
+            generated_at_epoch_secs,
+        };
+        *shared.runtime_edge_connections_cache.lock().await = Some(entry);
+    }
+
+    Some((generated_at_epoch_secs, payload))
+}
+
+async fn recompute_connections_payload(
+    shared: &ApiShared,
+    cache_ttl_ms: u64,
+    top_n: usize,
+) -> RuntimeEdgeConnectionsSummaryPayload {
+    let mut rows = Vec::<RuntimeEdgeConnectionUserData>::new();
+    let mut active_users = 0usize;
+    for entry in shared.stats.iter_user_stats() {
+        let user_stats = entry.value();
+        let current_connections = user_stats
+            .curr_connects
+            .load(std::sync::atomic::Ordering::Relaxed);
+        let total_octets = user_stats
+            .octets_from_client
+            .load(std::sync::atomic::Ordering::Relaxed)
+            .saturating_add(
+                user_stats
+                    .octets_to_client
+                    .load(std::sync::atomic::Ordering::Relaxed),
+            );
+        if current_connections > 0 {
+            active_users = active_users.saturating_add(1);
+        }
+        rows.push(RuntimeEdgeConnectionUserData {
+            username: entry.key().clone(),
+            current_connections,
+            total_octets,
+        });
+    }
+
+    let limit = top_n.max(1);
+    let mut by_connections = rows.clone();
+    by_connections.sort_by_key(|row| (Reverse(row.current_connections), row.username.clone()));
+    by_connections.truncate(limit);
+
+    let mut by_throughput = rows;
+    by_throughput.sort_by_key(|row| (Reverse(row.total_octets), row.username.clone()));
+    by_throughput.truncate(limit);
+
+    let telemetry = shared.stats.telemetry_policy();
+    RuntimeEdgeConnectionsSummaryPayload {
+        cache: RuntimeEdgeConnectionCacheData {
+            ttl_ms: cache_ttl_ms,
+            served_from_cache: false,
+            stale_cache_used: false,
+        },
+        totals: RuntimeEdgeConnectionTotalsData {
+            current_connections: shared.stats.get_current_connections_total(),
+            current_connections_me: shared.stats.get_current_connections_me(),
+            current_connections_direct: shared.stats.get_current_connections_direct(),
+            active_users,
+        },
+        top: RuntimeEdgeConnectionTopData {
+            limit,
+            by_connections,
+            by_throughput,
+        },
+        telemetry: RuntimeEdgeConnectionTelemetryData {
+            user_enabled: telemetry.user_enabled,
+            throughput_is_cumulative: true,
+        },
+    }
+}
+
+fn parse_recent_events_limit(query: Option<&str>, default_limit: usize, max_limit: usize) -> usize {
+    let Some(query) = query else {
+        return default_limit;
+    };
+    for pair in query.split('&') {
+        let mut split = pair.splitn(2, '=');
+        if split.next() == Some("limit")
+            && let Some(raw) = split.next()
+            && let Ok(parsed) = raw.parse::<usize>()
+        {
+            return parsed.clamp(1, max_limit);
+        }
+    }
+    default_limit
+}
+
+fn now_epoch_secs() -> u64 {
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_secs()
+}

src/api/runtime_min.rs

@@ -0,0 +1,534 @@
+use std::collections::BTreeSet;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use serde::Serialize;
+
+use crate::config::ProxyConfig;
+
+use super::ApiShared;
+
+const SOURCE_UNAVAILABLE_REASON: &str = "source_unavailable";
+
+#[derive(Serialize)]
+pub(super) struct SecurityWhitelistData {
+    pub(super) generated_at_epoch_secs: u64,
+    pub(super) enabled: bool,
+    pub(super) entries_total: usize,
+    pub(super) entries: Vec<String>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMePoolStateGenerationData {
+    pub(super) active_generation: u64,
+    pub(super) warm_generation: u64,
+    pub(super) pending_hardswap_generation: u64,
+    pub(super) pending_hardswap_age_secs: Option<u64>,
+    pub(super) draining_generations: Vec<u64>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMePoolStateHardswapData {
+    pub(super) enabled: bool,
+    pub(super) pending: bool,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMePoolStateWriterContourData {
+    pub(super) warm: usize,
+    pub(super) active: usize,
+    pub(super) draining: usize,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMePoolStateWriterHealthData {
+    pub(super) healthy: usize,
+    pub(super) degraded: usize,
+    pub(super) draining: usize,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMePoolStateWriterData {
+    pub(super) total: usize,
+    pub(super) alive_non_draining: usize,
+    pub(super) draining: usize,
+    pub(super) degraded: usize,
+    pub(super) contour: RuntimeMePoolStateWriterContourData,
+    pub(super) health: RuntimeMePoolStateWriterHealthData,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMePoolStateRefillDcData {
+    pub(super) dc: i16,
+    pub(super) family: &'static str,
+    pub(super) inflight: usize,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMePoolStateRefillData {
+    pub(super) inflight_endpoints_total: usize,
+    pub(super) inflight_dc_total: usize,
+    pub(super) by_dc: Vec<RuntimeMePoolStateRefillDcData>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMePoolStatePayload {
+    pub(super) generations: RuntimeMePoolStateGenerationData,
+    pub(super) hardswap: RuntimeMePoolStateHardswapData,
+    pub(super) writers: RuntimeMePoolStateWriterData,
+    pub(super) refill: RuntimeMePoolStateRefillData,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMePoolStateData {
+    pub(super) enabled: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) reason: Option<&'static str>,
+    pub(super) generated_at_epoch_secs: u64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) data: Option<RuntimeMePoolStatePayload>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMeQualityCountersData {
+    pub(super) idle_close_by_peer_total: u64,
+    pub(super) reader_eof_total: u64,
+    pub(super) kdf_drift_total: u64,
+    pub(super) kdf_port_only_drift_total: u64,
+    pub(super) reconnect_attempt_total: u64,
+    pub(super) reconnect_success_total: u64,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMeQualityRouteDropData {
+    pub(super) no_conn_total: u64,
+    pub(super) channel_closed_total: u64,
+    pub(super) queue_full_total: u64,
+    pub(super) queue_full_base_total: u64,
+    pub(super) queue_full_high_total: u64,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMeQualityDcRttData {
+    pub(super) dc: i16,
+    pub(super) rtt_ema_ms: Option<f64>,
+    pub(super) alive_writers: usize,
+    pub(super) required_writers: usize,
+    pub(super) coverage_pct: f64,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMeQualityPayload {
+    pub(super) counters: RuntimeMeQualityCountersData,
+    pub(super) route_drops: RuntimeMeQualityRouteDropData,
+    pub(super) dc_rtt: Vec<RuntimeMeQualityDcRttData>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeMeQualityData {
+    pub(super) enabled: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) reason: Option<&'static str>,
+    pub(super) generated_at_epoch_secs: u64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) data: Option<RuntimeMeQualityPayload>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeUpstreamQualityPolicyData {
+    pub(super) connect_retry_attempts: u32,
+    pub(super) connect_retry_backoff_ms: u64,
+    pub(super) connect_budget_ms: u64,
+    pub(super) unhealthy_fail_threshold: u32,
+    pub(super) connect_failfast_hard_errors: bool,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeUpstreamQualityCountersData {
+    pub(super) connect_attempt_total: u64,
+    pub(super) connect_success_total: u64,
+    pub(super) connect_fail_total: u64,
+    pub(super) connect_failfast_hard_error_total: u64,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeUpstreamQualitySummaryData {
+    pub(super) configured_total: usize,
+    pub(super) healthy_total: usize,
+    pub(super) unhealthy_total: usize,
+    pub(super) direct_total: usize,
+    pub(super) socks4_total: usize,
+    pub(super) socks5_total: usize,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeUpstreamQualityDcData {
+    pub(super) dc: i16,
+    pub(super) latency_ema_ms: Option<f64>,
+    pub(super) ip_preference: &'static str,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeUpstreamQualityUpstreamData {
+    pub(super) upstream_id: usize,
+    pub(super) route_kind: &'static str,
+    pub(super) address: String,
+    pub(super) weight: u16,
+    pub(super) scopes: String,
+    pub(super) healthy: bool,
+    pub(super) fails: u32,
+    pub(super) last_check_age_secs: u64,
+    pub(super) effective_latency_ms: Option<f64>,
+    pub(super) dc: Vec<RuntimeUpstreamQualityDcData>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeUpstreamQualityData {
+    pub(super) enabled: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) reason: Option<&'static str>,
+    pub(super) generated_at_epoch_secs: u64,
+    pub(super) policy: RuntimeUpstreamQualityPolicyData,
+    pub(super) counters: RuntimeUpstreamQualityCountersData,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) summary: Option<RuntimeUpstreamQualitySummaryData>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) upstreams: Option<Vec<RuntimeUpstreamQualityUpstreamData>>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeNatStunReflectionData {
+    pub(super) addr: String,
+    pub(super) age_secs: u64,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeNatStunFlagsData {
+    pub(super) nat_probe_enabled: bool,
+    pub(super) nat_probe_disabled_runtime: bool,
+    pub(super) nat_probe_attempts: u8,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeNatStunServersData {
+    pub(super) configured: Vec<String>,
+    pub(super) live: Vec<String>,
+    pub(super) live_total: usize,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeNatStunReflectionBlockData {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) v4: Option<RuntimeNatStunReflectionData>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) v6: Option<RuntimeNatStunReflectionData>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeNatStunPayload {
+    pub(super) flags: RuntimeNatStunFlagsData,
+    pub(super) servers: RuntimeNatStunServersData,
+    pub(super) reflection: RuntimeNatStunReflectionBlockData,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) stun_backoff_remaining_ms: Option<u64>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeNatStunData {
+    pub(super) enabled: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) reason: Option<&'static str>,
+    pub(super) generated_at_epoch_secs: u64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) data: Option<RuntimeNatStunPayload>,
+}
+
+pub(super) fn build_security_whitelist_data(cfg: &ProxyConfig) -> SecurityWhitelistData {
+    let entries = cfg
+        .server
+        .api
+        .whitelist
+        .iter()
+        .map(ToString::to_string)
+        .collect::<Vec<_>>();
+    SecurityWhitelistData {
+        generated_at_epoch_secs: now_epoch_secs(),
+        enabled: !entries.is_empty(),
+        entries_total: entries.len(),
+        entries,
+    }
+}
+
+pub(super) async fn build_runtime_me_pool_state_data(shared: &ApiShared) -> RuntimeMePoolStateData {
+    let now_epoch_secs = now_epoch_secs();
+    let Some(pool) = &shared.me_pool else {
+        return RuntimeMePoolStateData {
+            enabled: false,
+            reason: Some(SOURCE_UNAVAILABLE_REASON),
+            generated_at_epoch_secs: now_epoch_secs,
+            data: None,
+        };
+    };
+
+    let status = pool.api_status_snapshot().await;
+    let runtime = pool.api_runtime_snapshot().await;
+    let refill = pool.api_refill_snapshot().await;
+
+    let mut draining_generations = BTreeSet::<u64>::new();
+    let mut contour_warm = 0usize;
+    let mut contour_active = 0usize;
+    let mut contour_draining = 0usize;
+    let mut draining = 0usize;
+    let mut degraded = 0usize;
+    let mut healthy = 0usize;
+
+    for writer in &status.writers {
+        if writer.draining {
+            draining_generations.insert(writer.generation);
+            draining += 1;
+        }
+        if writer.degraded && !writer.draining {
+            degraded += 1;
+        }
+        if !writer.degraded && !writer.draining {
+            healthy += 1;
+        }
+        match writer.state {
+            "warm" => contour_warm += 1,
+            "active" => contour_active += 1,
+            _ => contour_draining += 1,
+        }
+    }
+
+    RuntimeMePoolStateData {
+        enabled: true,
+        reason: None,
+        generated_at_epoch_secs: status.generated_at_epoch_secs,
+        data: Some(RuntimeMePoolStatePayload {
+            generations: RuntimeMePoolStateGenerationData {
+                active_generation: runtime.active_generation,
+                warm_generation: runtime.warm_generation,
+                pending_hardswap_generation: runtime.pending_hardswap_generation,
+                pending_hardswap_age_secs: runtime.pending_hardswap_age_secs,
+                draining_generations: draining_generations.into_iter().collect(),
+            },
+            hardswap: RuntimeMePoolStateHardswapData {
+                enabled: runtime.hardswap_enabled,
+                pending: runtime.pending_hardswap_generation != 0,
+            },
+            writers: RuntimeMePoolStateWriterData {
+                total: status.writers.len(),
+                alive_non_draining: status.writers.len().saturating_sub(draining),
+                draining,
+                degraded,
+                contour: RuntimeMePoolStateWriterContourData {
+                    warm: contour_warm,
+                    active: contour_active,
+                    draining: contour_draining,
+                },
+                health: RuntimeMePoolStateWriterHealthData {
+                    healthy,
+                    degraded,
+                    draining,
+                },
+            },
+            refill: RuntimeMePoolStateRefillData {
+                inflight_endpoints_total: refill.inflight_endpoints_total,
+                inflight_dc_total: refill.inflight_dc_total,
+                by_dc: refill
+                    .by_dc
+                    .into_iter()
+                    .map(|entry| RuntimeMePoolStateRefillDcData {
+                        dc: entry.dc,
+                        family: entry.family,
+                        inflight: entry.inflight,
+                    })
+                    .collect(),
+            },
+        }),
+    }
+}
+
+pub(super) async fn build_runtime_me_quality_data(shared: &ApiShared) -> RuntimeMeQualityData {
+    let now_epoch_secs = now_epoch_secs();
+    let Some(pool) = &shared.me_pool else {
+        return RuntimeMeQualityData {
+            enabled: false,
+            reason: Some(SOURCE_UNAVAILABLE_REASON),
+            generated_at_epoch_secs: now_epoch_secs,
+            data: None,
+        };
+    };
+
+    let status = pool.api_status_snapshot().await;
+    RuntimeMeQualityData {
+        enabled: true,
+        reason: None,
+        generated_at_epoch_secs: status.generated_at_epoch_secs,
+        data: Some(RuntimeMeQualityPayload {
+            counters: RuntimeMeQualityCountersData {
+                idle_close_by_peer_total: shared.stats.get_me_idle_close_by_peer_total(),
+                reader_eof_total: shared.stats.get_me_reader_eof_total(),
+                kdf_drift_total: shared.stats.get_me_kdf_drift_total(),
+                kdf_port_only_drift_total: shared.stats.get_me_kdf_port_only_drift_total(),
+                reconnect_attempt_total: shared.stats.get_me_reconnect_attempts(),
+                reconnect_success_total: shared.stats.get_me_reconnect_success(),
+            },
+            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(),
+                queue_full_total: shared.stats.get_me_route_drop_queue_full(),
+                queue_full_base_total: shared.stats.get_me_route_drop_queue_full_base(),
+                queue_full_high_total: shared.stats.get_me_route_drop_queue_full_high(),
+            },
+            dc_rtt: status
+                .dcs
+                .into_iter()
+                .map(|dc| RuntimeMeQualityDcRttData {
+                    dc: dc.dc,
+                    rtt_ema_ms: dc.rtt_ms,
+                    alive_writers: dc.alive_writers,
+                    required_writers: dc.required_writers,
+                    coverage_pct: dc.coverage_pct,
+                })
+                .collect(),
+        }),
+    }
+}
+
+pub(super) async fn build_runtime_upstream_quality_data(
+    shared: &ApiShared,
+) -> RuntimeUpstreamQualityData {
+    let generated_at_epoch_secs = now_epoch_secs();
+    let policy = shared.upstream_manager.api_policy_snapshot();
+    let counters = RuntimeUpstreamQualityCountersData {
+        connect_attempt_total: shared.stats.get_upstream_connect_attempt_total(),
+        connect_success_total: shared.stats.get_upstream_connect_success_total(),
+        connect_fail_total: shared.stats.get_upstream_connect_fail_total(),
+        connect_failfast_hard_error_total: shared.stats.get_upstream_connect_failfast_hard_error_total(),
+    };
+
+    let Some(snapshot) = shared.upstream_manager.try_api_snapshot() else {
+        return RuntimeUpstreamQualityData {
+            enabled: false,
+            reason: Some(SOURCE_UNAVAILABLE_REASON),
+            generated_at_epoch_secs,
+            policy: RuntimeUpstreamQualityPolicyData {
+                connect_retry_attempts: policy.connect_retry_attempts,
+                connect_retry_backoff_ms: policy.connect_retry_backoff_ms,
+                connect_budget_ms: policy.connect_budget_ms,
+                unhealthy_fail_threshold: policy.unhealthy_fail_threshold,
+                connect_failfast_hard_errors: policy.connect_failfast_hard_errors,
+            },
+            counters,
+            summary: None,
+            upstreams: None,
+        };
+    };
+
+    RuntimeUpstreamQualityData {
+        enabled: true,
+        reason: None,
+        generated_at_epoch_secs,
+        policy: RuntimeUpstreamQualityPolicyData {
+            connect_retry_attempts: policy.connect_retry_attempts,
+            connect_retry_backoff_ms: policy.connect_retry_backoff_ms,
+            connect_budget_ms: policy.connect_budget_ms,
+            unhealthy_fail_threshold: policy.unhealthy_fail_threshold,
+            connect_failfast_hard_errors: policy.connect_failfast_hard_errors,
+        },
+        counters,
+        summary: Some(RuntimeUpstreamQualitySummaryData {
+            configured_total: snapshot.summary.configured_total,
+            healthy_total: snapshot.summary.healthy_total,
+            unhealthy_total: snapshot.summary.unhealthy_total,
+            direct_total: snapshot.summary.direct_total,
+            socks4_total: snapshot.summary.socks4_total,
+            socks5_total: snapshot.summary.socks5_total,
+        }),
+        upstreams: Some(
+            snapshot
+                .upstreams
+                .into_iter()
+                .map(|upstream| RuntimeUpstreamQualityUpstreamData {
+                    upstream_id: upstream.upstream_id,
+                    route_kind: match upstream.route_kind {
+                        crate::transport::UpstreamRouteKind::Direct => "direct",
+                        crate::transport::UpstreamRouteKind::Socks4 => "socks4",
+                        crate::transport::UpstreamRouteKind::Socks5 => "socks5",
+                    },
+                    address: upstream.address,
+                    weight: upstream.weight,
+                    scopes: upstream.scopes,
+                    healthy: upstream.healthy,
+                    fails: upstream.fails,
+                    last_check_age_secs: upstream.last_check_age_secs,
+                    effective_latency_ms: upstream.effective_latency_ms,
+                    dc: upstream
+                        .dc
+                        .into_iter()
+                        .map(|dc| RuntimeUpstreamQualityDcData {
+                            dc: dc.dc,
+                            latency_ema_ms: dc.latency_ema_ms,
+                            ip_preference: match dc.ip_preference {
+                                crate::transport::upstream::IpPreference::Unknown => "unknown",
+                                crate::transport::upstream::IpPreference::PreferV6 => "prefer_v6",
+                                crate::transport::upstream::IpPreference::PreferV4 => "prefer_v4",
+                                crate::transport::upstream::IpPreference::BothWork => "both_work",
+                                crate::transport::upstream::IpPreference::Unavailable => "unavailable",
+                            },
+                        })
+                        .collect(),
+                })
+                .collect(),
+        ),
+    }
+}
+
+pub(super) async fn build_runtime_nat_stun_data(shared: &ApiShared) -> RuntimeNatStunData {
+    let now_epoch_secs = now_epoch_secs();
+    let Some(pool) = &shared.me_pool else {
+        return RuntimeNatStunData {
+            enabled: false,
+            reason: Some(SOURCE_UNAVAILABLE_REASON),
+            generated_at_epoch_secs: now_epoch_secs,
+            data: None,
+        };
+    };
+
+    let snapshot = pool.api_nat_stun_snapshot().await;
+    RuntimeNatStunData {
+        enabled: true,
+        reason: None,
+        generated_at_epoch_secs: now_epoch_secs,
+        data: Some(RuntimeNatStunPayload {
+            flags: RuntimeNatStunFlagsData {
+                nat_probe_enabled: snapshot.nat_probe_enabled,
+                nat_probe_disabled_runtime: snapshot.nat_probe_disabled_runtime,
+                nat_probe_attempts: snapshot.nat_probe_attempts,
+            },
+            servers: RuntimeNatStunServersData {
+                configured: snapshot.configured_servers,
+                live: snapshot.live_servers.clone(),
+                live_total: snapshot.live_servers.len(),
+            },
+            reflection: RuntimeNatStunReflectionBlockData {
+                v4: snapshot.reflection_v4.map(|entry| RuntimeNatStunReflectionData {
+                    addr: entry.addr.to_string(),
+                    age_secs: entry.age_secs,
+                }),
+                v6: snapshot.reflection_v6.map(|entry| RuntimeNatStunReflectionData {
+                    addr: entry.addr.to_string(),
+                    age_secs: entry.age_secs,
+                }),
+            },
+            stun_backoff_remaining_ms: snapshot.stun_backoff_remaining_ms,
+        }),
+    }
+}
+
+fn now_epoch_secs() -> u64 {
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_secs()
+}

src/api/runtime_watch.rs

@@ -0,0 +1,66 @@
+use std::sync::Arc;
+use std::sync::atomic::Ordering;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use tokio::sync::watch;
+
+use crate::config::ProxyConfig;
+
+use super::ApiRuntimeState;
+use super::events::ApiEventStore;
+
+pub(super) fn spawn_runtime_watchers(
+    config_rx: watch::Receiver<Arc<ProxyConfig>>,
+    admission_rx: watch::Receiver<bool>,
+    runtime_state: Arc<ApiRuntimeState>,
+    runtime_events: Arc<ApiEventStore>,
+) {
+    let mut config_rx_reload = config_rx;
+    let runtime_state_reload = runtime_state.clone();
+    let runtime_events_reload = runtime_events.clone();
+    tokio::spawn(async move {
+        loop {
+            if config_rx_reload.changed().await.is_err() {
+                break;
+            }
+            runtime_state_reload
+                .config_reload_count
+                .fetch_add(1, Ordering::Relaxed);
+            runtime_state_reload
+                .last_config_reload_epoch_secs
+                .store(now_epoch_secs(), Ordering::Relaxed);
+            runtime_events_reload.record("config.reload.applied", "config receiver updated");
+        }
+    });
+
+    let mut admission_rx_watch = admission_rx;
+    tokio::spawn(async move {
+        runtime_state
+            .admission_open
+            .store(*admission_rx_watch.borrow(), Ordering::Relaxed);
+        runtime_events.record(
+            "admission.state",
+            format!("accepting_new_connections={}", *admission_rx_watch.borrow()),
+        );
+        loop {
+            if admission_rx_watch.changed().await.is_err() {
+                break;
+            }
+            let admission_open = *admission_rx_watch.borrow();
+            runtime_state
+                .admission_open
+                .store(admission_open, Ordering::Relaxed);
+            runtime_events.record(
+                "admission.state",
+                format!("accepting_new_connections={}", admission_open),
+            );
+        }
+    });
+}
+
+fn now_epoch_secs() -> u64 {
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_secs()
+}

src/api/runtime_zero.rs

@@ -0,0 +1,227 @@
+use std::sync::atomic::Ordering;
+
+use serde::Serialize;
+
+use crate::config::{MeFloorMode, ProxyConfig, UserMaxUniqueIpsMode};
+
+use super::ApiShared;
+
+#[derive(Serialize)]
+pub(super) struct SystemInfoData {
+    pub(super) version: String,
+    pub(super) target_arch: String,
+    pub(super) target_os: String,
+    pub(super) build_profile: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) git_commit: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) build_time_utc: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) rustc_version: Option<String>,
+    pub(super) process_started_at_epoch_secs: u64,
+    pub(super) uptime_seconds: f64,
+    pub(super) config_path: String,
+    pub(super) config_hash: String,
+    pub(super) config_reload_count: u64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) last_config_reload_epoch_secs: Option<u64>,
+}
+
+#[derive(Serialize)]
+pub(super) struct RuntimeGatesData {
+    pub(super) accepting_new_connections: bool,
+    pub(super) conditional_cast_enabled: bool,
+    pub(super) me_runtime_ready: bool,
+    pub(super) me2dc_fallback_enabled: bool,
+    pub(super) use_middle_proxy: bool,
+}
+
+#[derive(Serialize)]
+pub(super) struct EffectiveTimeoutLimits {
+    pub(super) client_handshake_secs: u64,
+    pub(super) tg_connect_secs: u64,
+    pub(super) client_keepalive_secs: u64,
+    pub(super) client_ack_secs: u64,
+    pub(super) me_one_retry: u8,
+    pub(super) me_one_timeout_ms: u64,
+}
+
+#[derive(Serialize)]
+pub(super) struct EffectiveUpstreamLimits {
+    pub(super) connect_retry_attempts: u32,
+    pub(super) connect_retry_backoff_ms: u64,
+    pub(super) connect_budget_ms: u64,
+    pub(super) unhealthy_fail_threshold: u32,
+    pub(super) connect_failfast_hard_errors: bool,
+}
+
+#[derive(Serialize)]
+pub(super) struct EffectiveMiddleProxyLimits {
+    pub(super) floor_mode: &'static str,
+    pub(super) adaptive_floor_idle_secs: u64,
+    pub(super) adaptive_floor_min_writers_single_endpoint: u8,
+    pub(super) adaptive_floor_recover_grace_secs: u64,
+    pub(super) reconnect_max_concurrent_per_dc: u32,
+    pub(super) reconnect_backoff_base_ms: u64,
+    pub(super) reconnect_backoff_cap_ms: u64,
+    pub(super) reconnect_fast_retry_count: u32,
+    pub(super) me2dc_fallback: bool,
+}
+
+#[derive(Serialize)]
+pub(super) struct EffectiveUserIpPolicyLimits {
+    pub(super) mode: &'static str,
+    pub(super) window_secs: u64,
+}
+
+#[derive(Serialize)]
+pub(super) struct EffectiveLimitsData {
+    pub(super) update_every_secs: u64,
+    pub(super) me_reinit_every_secs: u64,
+    pub(super) me_pool_force_close_secs: u64,
+    pub(super) timeouts: EffectiveTimeoutLimits,
+    pub(super) upstream: EffectiveUpstreamLimits,
+    pub(super) middle_proxy: EffectiveMiddleProxyLimits,
+    pub(super) user_ip_policy: EffectiveUserIpPolicyLimits,
+}
+
+#[derive(Serialize)]
+pub(super) struct SecurityPostureData {
+    pub(super) api_read_only: bool,
+    pub(super) api_whitelist_enabled: bool,
+    pub(super) api_whitelist_entries: usize,
+    pub(super) api_auth_header_enabled: bool,
+    pub(super) proxy_protocol_enabled: bool,
+    pub(super) log_level: String,
+    pub(super) telemetry_core_enabled: bool,
+    pub(super) telemetry_user_enabled: bool,
+    pub(super) telemetry_me_level: String,
+}
+
+pub(super) fn build_system_info_data(
+    shared: &ApiShared,
+    _cfg: &ProxyConfig,
+    revision: &str,
+) -> SystemInfoData {
+    let last_reload_epoch_secs = shared
+        .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 git_commit = option_env!("TELEMT_GIT_COMMIT")
+        .or(option_env!("VERGEN_GIT_SHA"))
+        .or(option_env!("GIT_COMMIT"))
+        .map(ToString::to_string);
+    let build_time_utc = option_env!("BUILD_TIME_UTC")
+        .or(option_env!("VERGEN_BUILD_TIMESTAMP"))
+        .map(ToString::to_string);
+    let rustc_version = option_env!("RUSTC_VERSION")
+        .or(option_env!("VERGEN_RUSTC_SEMVER"))
+        .map(ToString::to_string);
+
+    SystemInfoData {
+        version: env!("CARGO_PKG_VERSION").to_string(),
+        target_arch: std::env::consts::ARCH.to_string(),
+        target_os: std::env::consts::OS.to_string(),
+        build_profile: option_env!("PROFILE").unwrap_or("unknown").to_string(),
+        git_commit,
+        build_time_utc,
+        rustc_version,
+        process_started_at_epoch_secs: shared.runtime_state.process_started_at_epoch_secs,
+        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),
+        last_config_reload_epoch_secs,
+    }
+}
+
+pub(super) fn build_runtime_gates_data(shared: &ApiShared, cfg: &ProxyConfig) -> RuntimeGatesData {
+    let me_runtime_ready = if !cfg.general.use_middle_proxy {
+        true
+    } else {
+        shared
+            .me_pool
+            .as_ref()
+            .map(|pool| pool.is_runtime_ready())
+            .unwrap_or(false)
+    };
+
+    RuntimeGatesData {
+        accepting_new_connections: shared.runtime_state.admission_open.load(Ordering::Relaxed),
+        conditional_cast_enabled: cfg.general.use_middle_proxy,
+        me_runtime_ready,
+        me2dc_fallback_enabled: cfg.general.me2dc_fallback,
+        use_middle_proxy: cfg.general.use_middle_proxy,
+    }
+}
+
+pub(super) fn build_limits_effective_data(cfg: &ProxyConfig) -> EffectiveLimitsData {
+    EffectiveLimitsData {
+        update_every_secs: cfg.general.effective_update_every_secs(),
+        me_reinit_every_secs: cfg.general.effective_me_reinit_every_secs(),
+        me_pool_force_close_secs: cfg.general.effective_me_pool_force_close_secs(),
+        timeouts: EffectiveTimeoutLimits {
+            client_handshake_secs: cfg.timeouts.client_handshake,
+            tg_connect_secs: cfg.timeouts.tg_connect,
+            client_keepalive_secs: cfg.timeouts.client_keepalive,
+            client_ack_secs: cfg.timeouts.client_ack,
+            me_one_retry: cfg.timeouts.me_one_retry,
+            me_one_timeout_ms: cfg.timeouts.me_one_timeout_ms,
+        },
+        upstream: EffectiveUpstreamLimits {
+            connect_retry_attempts: cfg.general.upstream_connect_retry_attempts,
+            connect_retry_backoff_ms: cfg.general.upstream_connect_retry_backoff_ms,
+            connect_budget_ms: cfg.general.upstream_connect_budget_ms,
+            unhealthy_fail_threshold: cfg.general.upstream_unhealthy_fail_threshold,
+            connect_failfast_hard_errors: cfg.general.upstream_connect_failfast_hard_errors,
+        },
+        middle_proxy: EffectiveMiddleProxyLimits {
+            floor_mode: me_floor_mode_label(cfg.general.me_floor_mode),
+            adaptive_floor_idle_secs: cfg.general.me_adaptive_floor_idle_secs,
+            adaptive_floor_min_writers_single_endpoint: cfg
+                .general
+                .me_adaptive_floor_min_writers_single_endpoint,
+            adaptive_floor_recover_grace_secs: cfg.general.me_adaptive_floor_recover_grace_secs,
+            reconnect_max_concurrent_per_dc: cfg.general.me_reconnect_max_concurrent_per_dc,
+            reconnect_backoff_base_ms: cfg.general.me_reconnect_backoff_base_ms,
+            reconnect_backoff_cap_ms: cfg.general.me_reconnect_backoff_cap_ms,
+            reconnect_fast_retry_count: cfg.general.me_reconnect_fast_retry_count,
+            me2dc_fallback: cfg.general.me2dc_fallback,
+        },
+        user_ip_policy: EffectiveUserIpPolicyLimits {
+            mode: user_max_unique_ips_mode_label(cfg.access.user_max_unique_ips_mode),
+            window_secs: cfg.access.user_max_unique_ips_window_secs,
+        },
+    }
+}
+
+pub(super) fn build_security_posture_data(cfg: &ProxyConfig) -> SecurityPostureData {
+    SecurityPostureData {
+        api_read_only: cfg.server.api.read_only,
+        api_whitelist_enabled: !cfg.server.api.whitelist.is_empty(),
+        api_whitelist_entries: cfg.server.api.whitelist.len(),
+        api_auth_header_enabled: !cfg.server.api.auth_header.is_empty(),
+        proxy_protocol_enabled: cfg.server.proxy_protocol,
+        log_level: cfg.general.log_level.to_string(),
+        telemetry_core_enabled: cfg.general.telemetry.core_enabled,
+        telemetry_user_enabled: cfg.general.telemetry.user_enabled,
+        telemetry_me_level: cfg.general.telemetry.me_level.to_string(),
+    }
+}
+
+fn user_max_unique_ips_mode_label(mode: UserMaxUniqueIpsMode) -> &'static str {
+    match mode {
+        UserMaxUniqueIpsMode::ActiveWindow => "active_window",
+        UserMaxUniqueIpsMode::TimeWindow => "time_window",
+        UserMaxUniqueIpsMode::Combined => "combined",
+    }
+}
+
+fn me_floor_mode_label(mode: MeFloorMode) -> &'static str {
+    match mode {
+        MeFloorMode::Static => "static",
+        MeFloorMode::Adaptive => "adaptive",
+    }
+}

src/config/defaults.rs

@@ -15,6 +15,7 @@ const DEFAULT_ME_ADAPTIVE_FLOOR_RECOVER_GRACE_SECS: u64 = 180;
 const DEFAULT_USER_MAX_UNIQUE_IPS_WINDOW_SECS: u64 = 30;
 const DEFAULT_UPSTREAM_CONNECT_RETRY_ATTEMPTS: u32 = 2;
 const DEFAULT_UPSTREAM_UNHEALTHY_FAIL_THRESHOLD: u32 = 5;
+const DEFAULT_UPSTREAM_CONNECT_BUDGET_MS: u64 = 3000;
 const DEFAULT_LISTEN_ADDR_IPV6: &str = "::";
 const DEFAULT_ACCESS_USER: &str = "default";
 const DEFAULT_ACCESS_SECRET: &str = "00000000000000000000000000000000";
@@ -113,6 +114,15 @@ 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_proxy_protocol_header_timeout_ms() -> u64 {
+    500
+}
+
 pub(crate) fn default_prefer_4() -> u8 {
     4
 }
@@ -253,6 +263,10 @@ pub(crate) fn default_upstream_unhealthy_fail_threshold() -> u32 {
     DEFAULT_UPSTREAM_UNHEALTHY_FAIL_THRESHOLD
 }
 
+pub(crate) fn default_upstream_connect_budget_ms() -> u64 {
+    DEFAULT_UPSTREAM_CONNECT_BUDGET_MS
+}
+
 pub(crate) fn default_upstream_connect_failfast_hard_errors() -> bool {
     false
 }

src/config/hot_reload.rs

@@ -312,6 +312,12 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
         || old.server.api.minimal_runtime_enabled != new.server.api.minimal_runtime_enabled
         || 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_top_n != new.server.api.runtime_edge_top_n
+        || old.server.api.runtime_edge_events_capacity
+            != new.server.api.runtime_edge_events_capacity
         || old.server.api.read_only != new.server.api.read_only
     {
         warned = true;

src/config/load.rs

@@ -265,6 +265,12 @@ impl ProxyConfig {
             ));
         }
 
+        if config.general.upstream_connect_budget_ms == 0 {
+            return Err(ProxyError::Config(
+                "general.upstream_connect_budget_ms 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(),
@@ -456,12 +462,36 @@ impl ProxyConfig {
             ));
         }
 
+        if config.server.api.runtime_edge_cache_ttl_ms > 60_000 {
+            return Err(ProxyError::Config(
+                "server.api.runtime_edge_cache_ttl_ms must be within [0, 60000]".to_string(),
+            ));
+        }
+
+        if !(1..=1000).contains(&config.server.api.runtime_edge_top_n) {
+            return Err(ProxyError::Config(
+                "server.api.runtime_edge_top_n must be within [1, 1000]".to_string(),
+            ));
+        }
+
+        if !(16..=4096).contains(&config.server.api.runtime_edge_events_capacity) {
+            return Err(ProxyError::Config(
+                "server.api.runtime_edge_events_capacity must be within [16, 4096]".to_string(),
+            ));
+        }
+
         if config.server.api.listen.parse::<SocketAddr>().is_err() {
             return Err(ProxyError::Config(
                 "server.api.listen must be in IP:PORT format".to_string(),
             ));
         }
 
+        if config.server.proxy_protocol_header_timeout_ms == 0 {
+            return Err(ProxyError::Config(
+                "server.proxy_protocol_header_timeout_ms must be > 0".to_string(),
+            ));
+        }
+
         if config.general.effective_me_pool_force_close_secs() > 0
             && config.general.effective_me_pool_force_close_secs()
                 < config.general.me_pool_drain_ttl_secs
@@ -543,10 +573,11 @@ impl ProxyConfig {
             warn!("prefer_ipv6 is deprecated, use [network].prefer = 6");
         }
 
-        // Auto-enable NAT probe when Middle Proxy is requested.
+        if config.general.use_middle_proxy && !config.general.me_secret_atomic_snapshot {
-        if config.general.use_middle_proxy && !config.general.middle_proxy_nat_probe {
+            config.general.me_secret_atomic_snapshot = true;
-            config.general.middle_proxy_nat_probe = true;
+            warn!(
-            warn!("Auto-enabled middle_proxy_nat_probe for middle proxy mode");
+                "Auto-enabled me_secret_atomic_snapshot for middle proxy mode to keep KDF key_selector/secret coherent"
+            );
         }
 
         validate_network_cfg(&mut config.network)?;
@@ -789,6 +820,22 @@ mod tests {
             cfg.server.api.minimal_runtime_cache_ttl_ms,
             default_api_minimal_runtime_cache_ttl_ms()
         );
+        assert_eq!(
+            cfg.server.api.runtime_edge_enabled,
+            default_api_runtime_edge_enabled()
+        );
+        assert_eq!(
+            cfg.server.api.runtime_edge_cache_ttl_ms,
+            default_api_runtime_edge_cache_ttl_ms()
+        );
+        assert_eq!(
+            cfg.server.api.runtime_edge_top_n,
+            default_api_runtime_edge_top_n()
+        );
+        assert_eq!(
+            cfg.server.api.runtime_edge_events_capacity,
+            default_api_runtime_edge_events_capacity()
+        );
         assert_eq!(cfg.access.users, default_access_users());
         assert_eq!(
             cfg.access.user_max_unique_ips_mode,
@@ -905,6 +952,22 @@ mod tests {
             server.api.minimal_runtime_cache_ttl_ms,
             default_api_minimal_runtime_cache_ttl_ms()
         );
+        assert_eq!(
+            server.api.runtime_edge_enabled,
+            default_api_runtime_edge_enabled()
+        );
+        assert_eq!(
+            server.api.runtime_edge_cache_ttl_ms,
+            default_api_runtime_edge_cache_ttl_ms()
+        );
+        assert_eq!(
+            server.api.runtime_edge_top_n,
+            default_api_runtime_edge_top_n()
+        );
+        assert_eq!(
+            server.api.runtime_edge_events_capacity,
+            default_api_runtime_edge_events_capacity()
+        );
 
         let access = AccessConfig::default();
         assert_eq!(access.users, default_access_users());
@@ -1552,6 +1615,72 @@ mod tests {
         let _ = std::fs::remove_file(path);
     }
 
+    #[test]
+    fn api_runtime_edge_cache_ttl_out_of_range_is_rejected() {
+        let toml = r#"
+            [server.api]
+            enabled = true
+            listen = "127.0.0.1:9091"
+            runtime_edge_cache_ttl_ms = 70000
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_api_runtime_edge_cache_ttl_invalid_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let err = ProxyConfig::load(&path).unwrap_err().to_string();
+        assert!(err.contains("server.api.runtime_edge_cache_ttl_ms must be within [0, 60000]"));
+        let _ = std::fs::remove_file(path);
+    }
+
+    #[test]
+    fn api_runtime_edge_top_n_out_of_range_is_rejected() {
+        let toml = r#"
+            [server.api]
+            enabled = true
+            listen = "127.0.0.1:9091"
+            runtime_edge_top_n = 0
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_api_runtime_edge_top_n_invalid_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let err = ProxyConfig::load(&path).unwrap_err().to_string();
+        assert!(err.contains("server.api.runtime_edge_top_n must be within [1, 1000]"));
+        let _ = std::fs::remove_file(path);
+    }
+
+    #[test]
+    fn api_runtime_edge_events_capacity_out_of_range_is_rejected() {
+        let toml = r#"
+            [server.api]
+            enabled = true
+            listen = "127.0.0.1:9091"
+            runtime_edge_events_capacity = 8
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_api_runtime_edge_events_capacity_invalid_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let err = ProxyConfig::load(&path).unwrap_err().to_string();
+        assert!(err.contains("server.api.runtime_edge_events_capacity must be within [16, 4096]"));
+        let _ = std::fs::remove_file(path);
+    }
+
     #[test]
     fn force_close_bumped_when_below_drain_ttl() {
         let toml = r#"

src/config/types.rs

@@ -187,9 +187,10 @@ impl MeFloorMode {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
 #[serde(rename_all = "snake_case")]
 pub enum MeRouteNoWriterMode {
-    #[default]
     AsyncRecoveryFailfast,
     InlineRecoveryLegacy,
+    #[default]
+    HybridAsyncPersistent,
 }
 
 impl MeRouteNoWriterMode {
@@ -197,13 +198,16 @@ impl MeRouteNoWriterMode {
         match self {
             MeRouteNoWriterMode::AsyncRecoveryFailfast => 0,
             MeRouteNoWriterMode::InlineRecoveryLegacy => 1,
+            MeRouteNoWriterMode::HybridAsyncPersistent => 2,
         }
     }
 
     pub fn from_u8(raw: u8) -> Self {
         match raw {
+            0 => MeRouteNoWriterMode::AsyncRecoveryFailfast,
             1 => MeRouteNoWriterMode::InlineRecoveryLegacy,
-            _ => MeRouteNoWriterMode::AsyncRecoveryFailfast,
+            2 => MeRouteNoWriterMode::HybridAsyncPersistent,
+            _ => MeRouteNoWriterMode::HybridAsyncPersistent,
         }
     }
 }
@@ -528,6 +532,10 @@ pub struct GeneralConfig {
     #[serde(default = "default_upstream_connect_retry_backoff_ms")]
     pub upstream_connect_retry_backoff_ms: u64,
 
+    /// Total wall-clock budget in milliseconds for one upstream connect request across retries.
+    #[serde(default = "default_upstream_connect_budget_ms")]
+    pub upstream_connect_budget_ms: u64,
+
     /// Consecutive failed requests before upstream is marked unhealthy.
     #[serde(default = "default_upstream_unhealthy_fail_threshold")]
     pub upstream_unhealthy_fail_threshold: u32,
@@ -770,6 +778,7 @@ impl Default for GeneralConfig {
             me_adaptive_floor_recover_grace_secs: default_me_adaptive_floor_recover_grace_secs(),
             upstream_connect_retry_attempts: default_upstream_connect_retry_attempts(),
             upstream_connect_retry_backoff_ms: default_upstream_connect_retry_backoff_ms(),
+            upstream_connect_budget_ms: default_upstream_connect_budget_ms(),
             upstream_unhealthy_fail_threshold: default_upstream_unhealthy_fail_threshold(),
             upstream_connect_failfast_hard_errors: default_upstream_connect_failfast_hard_errors(),
             stun_iface_mismatch_ignore: false,
@@ -909,6 +918,22 @@ pub struct ApiConfig {
     #[serde(default = "default_api_minimal_runtime_cache_ttl_ms")]
     pub minimal_runtime_cache_ttl_ms: u64,
 
+    /// Enables runtime edge endpoints with optional cached aggregation.
+    #[serde(default = "default_api_runtime_edge_enabled")]
+    pub runtime_edge_enabled: bool,
+
+    /// Cache TTL for runtime edge aggregation payloads in milliseconds.
+    #[serde(default = "default_api_runtime_edge_cache_ttl_ms")]
+    pub runtime_edge_cache_ttl_ms: u64,
+
+    /// Top-N limit for edge connection leaderboard payloads.
+    #[serde(default = "default_api_runtime_edge_top_n")]
+    pub runtime_edge_top_n: usize,
+
+    /// Ring-buffer capacity for runtime edge control-plane events.
+    #[serde(default = "default_api_runtime_edge_events_capacity")]
+    pub runtime_edge_events_capacity: usize,
+
     /// Read-only mode: mutating endpoints are rejected.
     #[serde(default)]
     pub read_only: bool,
@@ -924,6 +949,10 @@ impl Default for ApiConfig {
             request_body_limit_bytes: default_api_request_body_limit_bytes(),
             minimal_runtime_enabled: default_api_minimal_runtime_enabled(),
             minimal_runtime_cache_ttl_ms: default_api_minimal_runtime_cache_ttl_ms(),
+            runtime_edge_enabled: default_api_runtime_edge_enabled(),
+            runtime_edge_cache_ttl_ms: default_api_runtime_edge_cache_ttl_ms(),
+            runtime_edge_top_n: default_api_runtime_edge_top_n(),
+            runtime_edge_events_capacity: default_api_runtime_edge_events_capacity(),
             read_only: false,
         }
     }
@@ -958,6 +987,10 @@ pub struct ServerConfig {
     #[serde(default)]
     pub proxy_protocol: bool,
 
+    /// Timeout in milliseconds for reading and parsing PROXY protocol headers.
+    #[serde(default = "default_proxy_protocol_header_timeout_ms")]
+    pub proxy_protocol_header_timeout_ms: u64,
+
     #[serde(default)]
     pub metrics_port: Option<u16>,
 
@@ -981,6 +1014,7 @@ impl Default for ServerConfig {
             listen_unix_sock_perm: None,
             listen_tcp: None,
             proxy_protocol: false,
+            proxy_protocol_header_timeout_ms: default_proxy_protocol_header_timeout_ms(),
             metrics_port: None,
             metrics_whitelist: default_metrics_whitelist(),
             api: ApiConfig::default(),

src/crypto/random.rs

@@ -21,6 +21,7 @@ struct SecureRandomInner {
     rng: StdRng,
     cipher: AesCtr,
     buffer: Vec<u8>,
+    buffer_start: usize,
 }
 
 impl Drop for SecureRandomInner {
@@ -48,6 +49,7 @@ impl SecureRandom {
                 rng,
                 cipher,
                 buffer: Vec::with_capacity(1024),
+                buffer_start: 0,
             }),
         }
     }
@@ -59,16 +61,29 @@ impl SecureRandom {
 
         let mut written = 0usize;
         while written < out.len() {
+            if inner.buffer_start >= inner.buffer.len() {
+                inner.buffer.clear();
+                inner.buffer_start = 0;
+            }
+
             if inner.buffer.is_empty() {
                 let mut chunk = vec![0u8; CHUNK_SIZE];
                 inner.rng.fill_bytes(&mut chunk);
                 inner.cipher.apply(&mut chunk);
                 inner.buffer.extend_from_slice(&chunk);
+                inner.buffer_start = 0;
             }
 
-            let take = (out.len() - written).min(inner.buffer.len());
+            let available = inner.buffer.len().saturating_sub(inner.buffer_start);
-            out[written..written + take].copy_from_slice(&inner.buffer[..take]);
+            let take = (out.len() - written).min(available);
-            inner.buffer.drain(..take);
+            let start = inner.buffer_start;
+            let end = start + take;
+            out[written..written + take].copy_from_slice(&inner.buffer[start..end]);
+            inner.buffer_start = end;
+            if inner.buffer_start >= inner.buffer.len() {
+                inner.buffer.clear();
+                inner.buffer_start = 0;
+            }
             written += take;
         }
     }

src/main.rs

@@ -4,11 +4,11 @@
 
 use std::net::SocketAddr;
 use std::sync::Arc;
-use std::time::{Duration, Instant};
+use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 use rand::Rng;
 use tokio::net::TcpListener;
 use tokio::signal;
-use tokio::sync::{Semaphore, mpsc};
+use tokio::sync::{Semaphore, mpsc, watch};
 use tracing::{debug, error, info, warn};
 use tracing_subscriber::{EnvFilter, fmt, prelude::*, reload};
 #[cfg(unix)]
@@ -241,6 +241,17 @@ fn format_uptime(total_secs: u64) -> String {
     format!("{} / {} seconds", parts.join(", "), total_secs)
 }
 
+async fn wait_until_admission_open(admission_rx: &mut watch::Receiver<bool>) -> bool {
+    loop {
+        if *admission_rx.borrow() {
+            return true;
+        }
+        if admission_rx.changed().await.is_err() {
+            return *admission_rx.borrow();
+        }
+    }
+}
+
 async fn load_startup_proxy_config_snapshot(
     url: &str,
     cache_path: Option<&str>,
@@ -358,6 +369,10 @@ async fn load_startup_proxy_config_snapshot(
 #[tokio::main]
 async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
     let process_started_at = Instant::now();
+    let process_started_at_epoch_secs = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_secs();
     let (config_path, cli_silent, cli_log_level) = parse_cli();
 
     let mut config = match ProxyConfig::load(&config_path) {
@@ -453,6 +468,7 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
         config.upstreams.clone(),
         config.general.upstream_connect_retry_attempts,
         config.general.upstream_connect_retry_backoff_ms,
+        config.general.upstream_connect_budget_ms,
         config.general.upstream_unhealthy_fail_threshold,
         config.general.upstream_connect_failfast_hard_errors,
         stats.clone(),
@@ -926,22 +942,21 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
         let mut grouped: BTreeMap<i32, Vec<MePingSample>> = BTreeMap::new();
         for report in me_results {
             for s in report.samples {
-                let key = s.dc.abs();
+                grouped.entry(s.dc).or_default().push(s);
-                grouped.entry(key).or_default().push(s);
             }
         }
 
         let family_order = if prefer_ipv6 {
-            vec![(MePingFamily::V6, true), (MePingFamily::V6, false), (MePingFamily::V4, true), (MePingFamily::V4, false)]
+            vec![MePingFamily::V6, MePingFamily::V4]
         } else {
-            vec![(MePingFamily::V4, true), (MePingFamily::V4, false), (MePingFamily::V6, true), (MePingFamily::V6, false)]
+            vec![MePingFamily::V4, MePingFamily::V6]
         };
 
-        for (dc_abs, samples) in grouped {
+        for (dc, samples) in grouped {
-            for (family, is_pos) in &family_order {
+            for family in &family_order {
                 let fam_samples: Vec<&MePingSample> = samples
                     .iter()
-                    .filter(|s| matches!(s.family, f if &f == family) && (s.dc >= 0) == *is_pos)
+                    .filter(|s| matches!(s.family, f if &f == family))
                     .collect();
                 if fam_samples.is_empty() {
                     continue;
@@ -951,7 +966,7 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
                     MePingFamily::V4 => "IPv4",
                     MePingFamily::V6 => "IPv6",
                 };
-                info!("    DC{} [{}]", dc_abs, fam_label);
+                info!("    DC{} [{}]", dc, fam_label);
                 for sample in fam_samples {
                     let line = format_sample_line(sample);
                     info!("{}", line);
@@ -1325,6 +1340,60 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
         print_proxy_links(&host, port, &config);
     }
 
+    let (admission_tx, admission_rx) = watch::channel(true);
+    if config.general.use_middle_proxy {
+        if let Some(pool) = me_pool.as_ref() {
+            let initial_open = pool.admission_ready_conditional_cast().await;
+            admission_tx.send_replace(initial_open);
+            if initial_open {
+                info!("Conditional-admission gate: open (ME pool ready)");
+            } else {
+                warn!("Conditional-admission gate: closed (ME pool is not ready)");
+            }
+
+            let pool_for_gate = pool.clone();
+            let admission_tx_gate = admission_tx.clone();
+            tokio::spawn(async move {
+                let mut gate_open = initial_open;
+                let mut open_streak = if initial_open { 1u32 } else { 0u32 };
+                let mut close_streak = if initial_open { 0u32 } else { 1u32 };
+                loop {
+                    let ready = pool_for_gate.admission_ready_conditional_cast().await;
+                    if ready {
+                        open_streak = open_streak.saturating_add(1);
+                        close_streak = 0;
+                        if !gate_open && open_streak >= 2 {
+                            gate_open = true;
+                            admission_tx_gate.send_replace(true);
+                            info!(
+                                open_streak,
+                                "Conditional-admission gate opened (ME pool recovered)"
+                            );
+                        }
+                    } else {
+                        close_streak = close_streak.saturating_add(1);
+                        open_streak = 0;
+                        if gate_open && close_streak >= 2 {
+                            gate_open = false;
+                            admission_tx_gate.send_replace(false);
+                            warn!(
+                                close_streak,
+                                "Conditional-admission gate closed (ME pool has uncovered DC groups)"
+                            );
+                        }
+                    }
+                    tokio::time::sleep(Duration::from_millis(250)).await;
+                }
+            });
+        } else {
+            admission_tx.send_replace(false);
+            warn!("Conditional-admission gate: closed (ME pool is unavailable)");
+        }
+    } else {
+        admission_tx.send_replace(true);
+    }
+    let _admission_tx_hold = admission_tx;
+
     // Unix socket setup (before listeners check so unix-only config works)
     let mut has_unix_listener = false;
     #[cfg(unix)]
@@ -1358,6 +1427,7 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
         has_unix_listener = true;
 
         let mut config_rx_unix: tokio::sync::watch::Receiver<Arc<ProxyConfig>> = config_rx.clone();
+        let mut admission_rx_unix = admission_rx.clone();
         let stats = stats.clone();
         let upstream_manager = upstream_manager.clone();
         let replay_checker = replay_checker.clone();
@@ -1373,6 +1443,10 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
             let unix_conn_counter = std::sync::Arc::new(std::sync::atomic::AtomicU64::new(1));
 
             loop {
+                if !wait_until_admission_open(&mut admission_rx_unix).await {
+                    warn!("Conditional-admission gate channel closed for unix listener");
+                    break;
+                }
                 match unix_listener.accept().await {
                     Ok((stream, _)) => {
                         let permit = match max_connections_unix.clone().acquire_owned().await {
@@ -1485,6 +1559,7 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
             let me_pool_api = me_pool.clone();
             let upstream_manager_api = upstream_manager.clone();
             let config_rx_api = config_rx.clone();
+            let admission_rx_api = admission_rx.clone();
             let config_path_api = std::path::PathBuf::from(&config_path);
             let startup_detected_ip_v4 = detected_ip_v4;
             let startup_detected_ip_v6 = detected_ip_v6;
@@ -1496,9 +1571,11 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
                     me_pool_api,
                     upstream_manager_api,
                     config_rx_api,
+                    admission_rx_api,
                     config_path_api,
                     startup_detected_ip_v4,
                     startup_detected_ip_v6,
+                    process_started_at_epoch_secs,
                 )
                 .await;
             });
@@ -1507,6 +1584,7 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
 
     for (listener, listener_proxy_protocol) in listeners {
         let mut config_rx: tokio::sync::watch::Receiver<Arc<ProxyConfig>> = config_rx.clone();
+        let mut admission_rx_tcp = admission_rx.clone();
         let stats = stats.clone();
         let upstream_manager = upstream_manager.clone();
         let replay_checker = replay_checker.clone();
@@ -1520,6 +1598,10 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
 
         tokio::spawn(async move {
             loop {
+                if !wait_until_admission_open(&mut admission_rx_tcp).await {
+                    warn!("Conditional-admission gate channel closed for tcp listener");
+                    break;
+                }
                 match listener.accept().await {
                     Ok((stream, peer_addr)) => {
                         let permit = match max_connections_tcp.clone().acquire_owned().await {

src/proxy/client.rs

@@ -97,8 +97,11 @@ where
         .unwrap_or_else(|_| "0.0.0.0:443".parse().unwrap());
 
     if proxy_protocol_enabled {
-        match parse_proxy_protocol(&mut stream, peer).await {
+        let proxy_header_timeout = Duration::from_millis(
-            Ok(info) => {
+            config.server.proxy_protocol_header_timeout_ms.max(1),
+        );
+        match timeout(proxy_header_timeout, parse_proxy_protocol(&mut stream, peer)).await {
+            Ok(Ok(info)) => {
                 debug!(
                     peer = %peer,
                     client = %info.src_addr,
@@ -110,12 +113,18 @@ where
                     local_addr = dst;
                 }
             }
-            Err(e) => {
+            Ok(Err(e)) => {
                 stats.increment_connects_bad();
                 warn!(peer = %peer, error = %e, "Invalid PROXY protocol header");
                 record_beobachten_class(&beobachten, &config, peer.ip(), "other");
                 return Err(e);
             }
+            Err(_) => {
+                stats.increment_connects_bad();
+                warn!(peer = %peer, timeout_ms = proxy_header_timeout.as_millis(), "PROXY protocol header timeout");
+                record_beobachten_class(&beobachten, &config, peer.ip(), "other");
+                return Err(ProxyError::InvalidProxyProtocol);
+            }
         }
     }
 
@@ -161,7 +170,7 @@ where
 
             let (read_half, write_half) = tokio::io::split(stream);
 
-            let (mut tls_reader, tls_writer, _tls_user) = match handle_tls_handshake(
+            let (mut tls_reader, tls_writer, tls_user) = match handle_tls_handshake(
                 &handshake, read_half, write_half, real_peer,
                 &config, &replay_checker, &rng, tls_cache.clone(),
             ).await {
@@ -190,7 +199,7 @@ where
 
             let (crypto_reader, crypto_writer, success) = match handle_mtproto_handshake(
                 &mtproto_handshake, tls_reader, tls_writer, real_peer,
-                &config, &replay_checker, true,
+                &config, &replay_checker, true, Some(tls_user.as_str()),
             ).await {
                 HandshakeResult::Success(result) => result,
                 HandshakeResult::BadClient { reader: _, writer: _ } => {
@@ -234,7 +243,7 @@ where
 
             let (crypto_reader, crypto_writer, success) = match handle_mtproto_handshake(
                 &handshake, read_half, write_half, real_peer,
-                &config, &replay_checker, false,
+                &config, &replay_checker, false, None,
             ).await {
                 HandshakeResult::Success(result) => result,
                 HandshakeResult::BadClient { reader, writer } => {
@@ -415,8 +424,16 @@ impl RunningClientHandler {
         let mut local_addr = self.stream.local_addr().map_err(ProxyError::Io)?;
 
         if self.proxy_protocol_enabled {
-            match parse_proxy_protocol(&mut self.stream, self.peer).await {
+            let proxy_header_timeout = Duration::from_millis(
-                Ok(info) => {
+                self.config.server.proxy_protocol_header_timeout_ms.max(1),
+            );
+            match timeout(
+                proxy_header_timeout,
+                parse_proxy_protocol(&mut self.stream, self.peer),
+            )
+            .await
+            {
+                Ok(Ok(info)) => {
                     debug!(
                         peer = %self.peer,
                         client = %info.src_addr,
@@ -428,7 +445,7 @@ impl RunningClientHandler {
                         local_addr = dst;
                     }
                 }
-                Err(e) => {
+                Ok(Err(e)) => {
                     self.stats.increment_connects_bad();
                     warn!(peer = %self.peer, error = %e, "Invalid PROXY protocol header");
                     record_beobachten_class(
@@ -439,6 +456,21 @@ impl RunningClientHandler {
                     );
                     return Err(e);
                 }
+                Err(_) => {
+                    self.stats.increment_connects_bad();
+                    warn!(
+                        peer = %self.peer,
+                        timeout_ms = proxy_header_timeout.as_millis(),
+                        "PROXY protocol header timeout"
+                    );
+                    record_beobachten_class(
+                        &self.beobachten,
+                        &self.config,
+                        self.peer.ip(),
+                        "other",
+                    );
+                    return Err(ProxyError::InvalidProxyProtocol);
+                }
             }
         }
 
@@ -494,7 +526,7 @@ impl RunningClientHandler {
 
         let (read_half, write_half) = self.stream.into_split();
 
-        let (mut tls_reader, tls_writer, _tls_user) = match handle_tls_handshake(
+        let (mut tls_reader, tls_writer, tls_user) = match handle_tls_handshake(
             &handshake,
             read_half,
             write_half,
@@ -538,6 +570,7 @@ impl RunningClientHandler {
             &config,
             &replay_checker,
             true,
+            Some(tls_user.as_str()),
         )
         .await
         {
@@ -611,6 +644,7 @@ impl RunningClientHandler {
             &config,
             &replay_checker,
             false,
+            None,
         )
         .await
         {

src/proxy/direct_relay.rs

@@ -34,7 +34,7 @@ where
     let user = &success.user;
     let dc_addr = get_dc_addr_static(success.dc_idx, &config)?;
 
-    info!(
+    debug!(
         user = %user,
         peer = %success.peer,
         dc = success.dc_idx,
@@ -57,6 +57,7 @@ where
 
     stats.increment_user_connects(user);
     stats.increment_user_curr_connects(user);
+    stats.increment_current_connections_direct();
 
     let relay_result = relay_bidirectional(
         client_reader,
@@ -69,6 +70,7 @@ where
     )
     .await;
 
+    stats.decrement_current_connections_direct();
     stats.decrement_user_curr_connects(user);
 
     match &relay_result {

src/proxy/handshake.rs

@@ -6,7 +6,7 @@ use std::net::SocketAddr;
 use std::sync::Arc;
 use std::time::Duration;
 use tokio::io::{AsyncRead, AsyncWrite, AsyncWriteExt};
-use tracing::{debug, warn, trace, info};
+use tracing::{debug, warn, trace};
 use zeroize::Zeroize;
 
 use crate::crypto::{sha256, AesCtr, SecureRandom};
@@ -19,6 +19,31 @@ use crate::stats::ReplayChecker;
 use crate::config::ProxyConfig;
 use crate::tls_front::{TlsFrontCache, emulator};
 
+fn decode_user_secrets(
+    config: &ProxyConfig,
+    preferred_user: Option<&str>,
+) -> Vec<(String, Vec<u8>)> {
+    let mut secrets = Vec::with_capacity(config.access.users.len());
+
+    if let Some(preferred) = preferred_user
+        && let Some(secret_hex) = config.access.users.get(preferred)
+        && let Ok(bytes) = hex::decode(secret_hex)
+    {
+        secrets.push((preferred.to_string(), bytes));
+    }
+
+    for (name, secret_hex) in &config.access.users {
+        if preferred_user.is_some_and(|preferred| preferred == name.as_str()) {
+            continue;
+        }
+        if let Ok(bytes) = hex::decode(secret_hex) {
+            secrets.push((name.clone(), bytes));
+        }
+    }
+
+    secrets
+}
+
 /// Result of successful handshake
 ///
 /// Key material (`dec_key`, `dec_iv`, `enc_key`, `enc_iv`) is
@@ -82,11 +107,7 @@ where
         return HandshakeResult::BadClient { reader, writer };
     }
 
-    let secrets: Vec<(String, Vec<u8>)> = config.access.users.iter()
+    let secrets = decode_user_secrets(config, None);
-        .filter_map(|(name, hex)| {
-            hex::decode(hex).ok().map(|bytes| (name.clone(), bytes))
-        })
-        .collect();
 
     let validation = match tls::validate_tls_handshake(
         handshake,
@@ -201,7 +222,7 @@ where
         return HandshakeResult::Error(ProxyError::Io(e));
     }
 
-    info!(
+    debug!(
         peer = %peer,
         user = %validation.user,
         "TLS handshake successful"
@@ -223,6 +244,7 @@ pub async fn handle_mtproto_handshake<R, W>(
     config: &ProxyConfig,
     replay_checker: &ReplayChecker,
     is_tls: bool,
+    preferred_user: Option<&str>,
 ) -> HandshakeResult<(CryptoReader<R>, CryptoWriter<W>, HandshakeSuccess), R, W>
 where
     R: AsyncRead + Unpin + Send,
@@ -239,11 +261,9 @@ where
 
     let enc_prekey_iv: Vec<u8> = dec_prekey_iv.iter().rev().copied().collect();
 
-    for (user, secret_hex) in &config.access.users {
+    let decoded_users = decode_user_secrets(config, preferred_user);
-        let secret = match hex::decode(secret_hex) {
+
-            Ok(s) => s,
+    for (user, secret) in decoded_users {
-            Err(_) => continue,
-        };
 
         let dec_prekey = &dec_prekey_iv[..PREKEY_LEN];
         let dec_iv_bytes = &dec_prekey_iv[PREKEY_LEN..];
@@ -311,7 +331,7 @@ where
             is_tls,
         };
 
-        info!(
+        debug!(
             peer = %peer,
             user = %user,
             dc = dc_idx,

src/proxy/middle_relay.rs

@@ -8,7 +8,7 @@ use std::time::{Duration, Instant};
 
 use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
 use tokio::sync::{mpsc, oneshot};
-use tracing::{debug, info, trace, warn};
+use tracing::{debug, trace, warn};
 
 use crate::config::ProxyConfig;
 use crate::crypto::SecureRandom;
@@ -210,7 +210,7 @@ where
     let proto_tag = success.proto_tag;
     let pool_generation = me_pool.current_generation();
 
-    info!(
+    debug!(
         user = %user,
         peer = %peer,
         dc = success.dc_idx,
@@ -237,6 +237,7 @@ where
 
     stats.increment_user_connects(&user);
     stats.increment_user_curr_connects(&user);
+    stats.increment_current_connections_me();
 
     // Per-user ad_tag from access.user_ad_tags; fallback to general.ad_tag (hot-reloadable)
     let user_tag: Option<Vec<u8>> = config
@@ -466,6 +467,7 @@ where
         "ME relay cleanup"
     );
     me_pool.registry().unregister(conn_id).await;
+    stats.decrement_current_connections_me();
     stats.decrement_user_curr_connects(&user);
     result
 }

src/stats/mod.rs

@@ -25,6 +25,8 @@ use self::telemetry::TelemetryPolicy;
 pub struct Stats {
     connects_all: AtomicU64,
     connects_bad: AtomicU64,
+    current_connections_direct: AtomicU64,
+    current_connections_me: AtomicU64,
     handshake_timeouts: AtomicU64,
     upstream_connect_attempt_total: AtomicU64,
     upstream_connect_success_total: AtomicU64,
@@ -150,6 +152,24 @@ impl Stats {
         self.telemetry_me_level().allows_debug()
     }
 
+    fn decrement_atomic_saturating(counter: &AtomicU64) {
+        let mut current = counter.load(Ordering::Relaxed);
+        loop {
+            if current == 0 {
+                break;
+            }
+            match counter.compare_exchange_weak(
+                current,
+                current - 1,
+                Ordering::Relaxed,
+                Ordering::Relaxed,
+            ) {
+                Ok(_) => break,
+                Err(actual) => current = actual,
+            }
+        }
+    }
+
     pub fn apply_telemetry_policy(&self, policy: TelemetryPolicy) {
         self.telemetry_core_enabled
             .store(policy.core_enabled, Ordering::Relaxed);
@@ -177,6 +197,18 @@ impl Stats {
             self.connects_bad.fetch_add(1, Ordering::Relaxed);
         }
     }
+    pub fn increment_current_connections_direct(&self) {
+        self.current_connections_direct.fetch_add(1, Ordering::Relaxed);
+    }
+    pub fn decrement_current_connections_direct(&self) {
+        Self::decrement_atomic_saturating(&self.current_connections_direct);
+    }
+    pub fn increment_current_connections_me(&self) {
+        self.current_connections_me.fetch_add(1, Ordering::Relaxed);
+    }
+    pub fn decrement_current_connections_me(&self) {
+        Self::decrement_atomic_saturating(&self.current_connections_me);
+    }
     pub fn increment_handshake_timeouts(&self) {
         if self.telemetry_core_enabled() {
             self.handshake_timeouts.fetch_add(1, Ordering::Relaxed);
@@ -646,6 +678,16 @@ impl Stats {
     }
     pub fn get_connects_all(&self) -> u64 { self.connects_all.load(Ordering::Relaxed) }
     pub fn get_connects_bad(&self) -> u64 { self.connects_bad.load(Ordering::Relaxed) }
+    pub fn get_current_connections_direct(&self) -> u64 {
+        self.current_connections_direct.load(Ordering::Relaxed)
+    }
+    pub fn get_current_connections_me(&self) -> u64 {
+        self.current_connections_me.load(Ordering::Relaxed)
+    }
+    pub fn get_current_connections_total(&self) -> u64 {
+        self.get_current_connections_direct()
+            .saturating_add(self.get_current_connections_me())
+    }
     pub fn get_me_keepalive_sent(&self) -> u64 { self.me_keepalive_sent.load(Ordering::Relaxed) }
     pub fn get_me_keepalive_failed(&self) -> u64 { self.me_keepalive_failed.load(Ordering::Relaxed) }
     pub fn get_me_keepalive_pong(&self) -> u64 { self.me_keepalive_pong.load(Ordering::Relaxed) }
@@ -846,16 +888,30 @@ impl Stats {
         if !self.telemetry_user_enabled() {
             return;
         }
-        self.user_stats.entry(user.to_string()).or_default()
+        if let Some(stats) = self.user_stats.get(user) {
-            .connects.fetch_add(1, Ordering::Relaxed);
+            stats.connects.fetch_add(1, Ordering::Relaxed);
+            return;
+        }
+        self.user_stats
+            .entry(user.to_string())
+            .or_default()
+            .connects
+            .fetch_add(1, Ordering::Relaxed);
     }
     
     pub fn increment_user_curr_connects(&self, user: &str) {
         if !self.telemetry_user_enabled() {
             return;
         }
-        self.user_stats.entry(user.to_string()).or_default()
+        if let Some(stats) = self.user_stats.get(user) {
-            .curr_connects.fetch_add(1, Ordering::Relaxed);
+            stats.curr_connects.fetch_add(1, Ordering::Relaxed);
+            return;
+        }
+        self.user_stats
+            .entry(user.to_string())
+            .or_default()
+            .curr_connects
+            .fetch_add(1, Ordering::Relaxed);
     }
     
     pub fn decrement_user_curr_connects(&self, user: &str) {
@@ -889,32 +945,60 @@ impl Stats {
         if !self.telemetry_user_enabled() {
             return;
         }
-        self.user_stats.entry(user.to_string()).or_default()
+        if let Some(stats) = self.user_stats.get(user) {
-            .octets_from_client.fetch_add(bytes, Ordering::Relaxed);
+            stats.octets_from_client.fetch_add(bytes, Ordering::Relaxed);
+            return;
+        }
+        self.user_stats
+            .entry(user.to_string())
+            .or_default()
+            .octets_from_client
+            .fetch_add(bytes, Ordering::Relaxed);
     }
     
     pub fn add_user_octets_to(&self, user: &str, bytes: u64) {
         if !self.telemetry_user_enabled() {
             return;
         }
-        self.user_stats.entry(user.to_string()).or_default()
+        if let Some(stats) = self.user_stats.get(user) {
-            .octets_to_client.fetch_add(bytes, Ordering::Relaxed);
+            stats.octets_to_client.fetch_add(bytes, Ordering::Relaxed);
+            return;
+        }
+        self.user_stats
+            .entry(user.to_string())
+            .or_default()
+            .octets_to_client
+            .fetch_add(bytes, Ordering::Relaxed);
     }
     
     pub fn increment_user_msgs_from(&self, user: &str) {
         if !self.telemetry_user_enabled() {
             return;
         }
-        self.user_stats.entry(user.to_string()).or_default()
+        if let Some(stats) = self.user_stats.get(user) {
-            .msgs_from_client.fetch_add(1, Ordering::Relaxed);
+            stats.msgs_from_client.fetch_add(1, Ordering::Relaxed);
+            return;
+        }
+        self.user_stats
+            .entry(user.to_string())
+            .or_default()
+            .msgs_from_client
+            .fetch_add(1, Ordering::Relaxed);
     }
     
     pub fn increment_user_msgs_to(&self, user: &str) {
         if !self.telemetry_user_enabled() {
             return;
         }
-        self.user_stats.entry(user.to_string()).or_default()
+        if let Some(stats) = self.user_stats.get(user) {
-            .msgs_to_client.fetch_add(1, Ordering::Relaxed);
+            stats.msgs_to_client.fetch_add(1, Ordering::Relaxed);
+            return;
+        }
+        self.user_stats
+            .entry(user.to_string())
+            .or_default()
+            .msgs_to_client
+            .fetch_add(1, Ordering::Relaxed);
     }
     
     pub fn get_user_total_octets(&self, user: &str) -> u64 {

src/transport/middle_proxy/handshake.rs

@@ -84,38 +84,7 @@ impl MePool {
     }
 
     async fn resolve_dc_idx_for_endpoint(&self, addr: SocketAddr) -> Option<i16> {
-        if addr.is_ipv4() {
+        i16::try_from(self.resolve_dc_for_endpoint(addr).await).ok()
-            let map = self.proxy_map_v4.read().await;
-            for (dc, addrs) in map.iter() {
-                if addrs
-                    .iter()
-                    .any(|(ip, port)| SocketAddr::new(*ip, *port) == addr)
-                {
-                    let abs_dc = dc.abs();
-                    if abs_dc > 0
-                        && let Ok(dc_idx) = i16::try_from(abs_dc)
-                    {
-                        return Some(dc_idx);
-                    }
-                }
-            }
-        } else {
-            let map = self.proxy_map_v6.read().await;
-            for (dc, addrs) in map.iter() {
-                if addrs
-                    .iter()
-                    .any(|(ip, port)| SocketAddr::new(*ip, *port) == addr)
-                {
-                    let abs_dc = dc.abs();
-                    if abs_dc > 0
-                        && let Ok(dc_idx) = i16::try_from(abs_dc)
-                    {
-                        return Some(dc_idx);
-                    }
-                }
-            }
-        }
-        None
     }
 
     fn direct_bind_ip_for_stun(
@@ -387,9 +356,11 @@ impl MePool {
             socks_bound_addr.map(|value| value.ip()),
             client_port_source,
         );
-        let mut kdf_fingerprint_guard = self.kdf_material_fingerprint.lock().await;
+        let previous_kdf_fingerprint = {
-        if let Some((prev_fingerprint, prev_client_port)) =
+            let kdf_fingerprint_guard = self.kdf_material_fingerprint.read().await;
             kdf_fingerprint_guard.get(&peer_addr_nat).copied()
+        };
+        if let Some((prev_fingerprint, prev_client_port)) = previous_kdf_fingerprint
         {
             if prev_fingerprint != kdf_fingerprint {
                 self.stats.increment_me_kdf_drift_total();
@@ -416,6 +387,9 @@ impl MePool {
                 );
             }
         }
+        // Keep fingerprint updates eventually consistent for diagnostics while avoiding
+        // serializing all concurrent handshakes on a single async mutex.
+        let mut kdf_fingerprint_guard = self.kdf_material_fingerprint.write().await;
         kdf_fingerprint_guard.insert(peer_addr_nat, (kdf_fingerprint, client_port_for_kdf));
         drop(kdf_fingerprint_guard);
 

src/transport/middle_proxy/health.rs

@@ -102,7 +102,7 @@ async fn check_family(
 
     let mut dc_endpoints = HashMap::<i32, Vec<SocketAddr>>::new();
     for (dc, addrs) in map {
-        let entry = dc_endpoints.entry(dc.abs()).or_default();
+        let entry = dc_endpoints.entry(dc).or_default();
         for (ip, port) in addrs {
             entry.push(SocketAddr::new(ip, port));
         }

src/transport/middle_proxy/mod.rs

@@ -10,6 +10,7 @@ mod pool_init;
 mod pool_nat;
 mod pool_refill;
 mod pool_reinit;
+mod pool_runtime_api;
 mod pool_writer;
 mod ping;
 mod reader;

src/transport/middle_proxy/pool.rs

@@ -119,6 +119,8 @@ pub struct MePool {
     pub(super) ping_tracker: Arc<Mutex<HashMap<i64, (std::time::Instant, u64)>>>,
     pub(super) rtt_stats: Arc<Mutex<HashMap<u64, (f64, f64)>>>,
     pub(super) nat_reflection_cache: Arc<Mutex<NatReflectionCache>>,
+    pub(super) nat_reflection_singleflight_v4: Arc<Mutex<()>>,
+    pub(super) nat_reflection_singleflight_v6: Arc<Mutex<()>>,
     pub(super) writer_available: Arc<Notify>,
     pub(super) refill_inflight: Arc<Mutex<HashSet<SocketAddr>>>,
     pub(super) refill_inflight_dc: Arc<Mutex<HashSet<RefillDcKey>>>,
@@ -132,7 +134,7 @@ pub struct MePool {
     pub(super) pending_hardswap_map_hash: AtomicU64,
     pub(super) hardswap: AtomicBool,
     pub(super) endpoint_quarantine: Arc<Mutex<HashMap<SocketAddr, Instant>>>,
-    pub(super) kdf_material_fingerprint: Arc<Mutex<HashMap<SocketAddr, (u64, u16)>>>,
+    pub(super) kdf_material_fingerprint: Arc<RwLock<HashMap<SocketAddr, (u64, u16)>>>,
     pub(super) me_pool_drain_ttl_secs: AtomicU64,
     pub(super) me_pool_force_close_secs: AtomicU64,
     pub(super) me_pool_min_fresh_ratio_permille: AtomicU32,
@@ -318,11 +320,13 @@ impl MePool {
             pool_size: 2,
             proxy_map_v4: Arc::new(RwLock::new(proxy_map_v4)),
             proxy_map_v6: Arc::new(RwLock::new(proxy_map_v6)),
-            default_dc: AtomicI32::new(default_dc.unwrap_or(0)),
+            default_dc: AtomicI32::new(default_dc.unwrap_or(2)),
             next_writer_id: AtomicU64::new(1),
             ping_tracker: Arc::new(Mutex::new(HashMap::new())),
             rtt_stats: Arc::new(Mutex::new(HashMap::new())),
             nat_reflection_cache: Arc::new(Mutex::new(NatReflectionCache::default())),
+            nat_reflection_singleflight_v4: Arc::new(Mutex::new(())),
+            nat_reflection_singleflight_v6: Arc::new(Mutex::new(())),
             writer_available: Arc::new(Notify::new()),
             refill_inflight: Arc::new(Mutex::new(HashSet::new())),
             refill_inflight_dc: Arc::new(Mutex::new(HashSet::new())),
@@ -335,7 +339,7 @@ impl MePool {
             pending_hardswap_map_hash: AtomicU64::new(0),
             hardswap: AtomicBool::new(hardswap),
             endpoint_quarantine: Arc::new(Mutex::new(HashMap::new())),
-            kdf_material_fingerprint: Arc::new(Mutex::new(HashMap::new())),
+            kdf_material_fingerprint: Arc::new(RwLock::new(HashMap::new())),
             me_pool_drain_ttl_secs: AtomicU64::new(me_pool_drain_ttl_secs),
             me_pool_force_close_secs: AtomicU64::new(me_pool_force_close_secs),
             me_pool_min_fresh_ratio_permille: AtomicU32::new(Self::ratio_to_permille(
@@ -621,6 +625,58 @@ impl MePool {
         order
     }
 
+    pub(super) fn default_dc_for_routing(&self) -> i32 {
+        let dc = self.default_dc.load(Ordering::Relaxed);
+        if dc == 0 { 2 } else { dc }
+    }
+
+    pub(super) fn dc_lookup_chain_for_target(&self, target_dc: i32) -> Vec<i32> {
+        let mut out = Vec::with_capacity(1);
+        if target_dc != 0 {
+            out.push(target_dc);
+        } else {
+            // Use default DC only when target DC is unknown and pinning is not established.
+            let fallback_dc = self.default_dc_for_routing();
+            out.push(fallback_dc);
+        }
+        out
+    }
+
+    pub(super) async fn resolve_dc_for_endpoint(&self, addr: SocketAddr) -> i32 {
+        let map_guard = if addr.is_ipv4() {
+            self.proxy_map_v4.read().await
+        } else {
+            self.proxy_map_v6.read().await
+        };
+
+        let mut matched_dc: Option<i32> = None;
+        let mut ambiguous = false;
+        for (dc, addrs) in map_guard.iter() {
+            if addrs
+                .iter()
+                .any(|(ip, port)| SocketAddr::new(*ip, *port) == addr)
+            {
+                match matched_dc {
+                    None => matched_dc = Some(*dc),
+                    Some(prev_dc) if prev_dc == *dc => {}
+                    Some(_) => {
+                        ambiguous = true;
+                        break;
+                    }
+                }
+            }
+        }
+        drop(map_guard);
+
+        if !ambiguous
+            && let Some(dc) = matched_dc
+        {
+            return dc;
+        }
+
+        self.default_dc_for_routing()
+    }
+
     pub(super) async fn proxy_map_for_family(
         &self,
         family: IpFamily,

src/transport/middle_proxy/pool_init.rs

@@ -1,4 +1,4 @@
-use std::collections::{HashMap, HashSet};
+use std::collections::HashSet;
 use std::net::{IpAddr, SocketAddr};
 use std::sync::Arc;
 
@@ -14,10 +14,12 @@ use super::pool::MePool;
 impl MePool {
     pub async fn init(self: &Arc<Self>, pool_size: usize, rng: &Arc<SecureRandom>) -> Result<()> {
         let family_order = self.family_order();
+        let connect_concurrency = self.me_reconnect_max_concurrent_per_dc.max(1) as usize;
         let ks = self.key_selector().await;
         info!(
             me_servers = self.proxy_map_v4.read().await.len(),
             pool_size,
+            connect_concurrency,
             key_selector = format_args!("0x{ks:08x}"),
             secret_len = self.proxy_secret.read().await.secret.len(),
             "Initializing ME pool"
@@ -25,39 +27,49 @@ impl MePool {
 
         for family in family_order {
             let map = self.proxy_map_for_family(family).await;
-            let mut grouped_dc_addrs: HashMap<i32, Vec<(IpAddr, u16)>> = HashMap::new();
+            let mut dc_addrs: Vec<(i32, Vec<(IpAddr, u16)>)> = map
-            for (dc, addrs) in map {
-                if addrs.is_empty() {
-                    continue;
-                }
-                grouped_dc_addrs.entry(dc.abs()).or_default().extend(addrs);
-            }
-            let mut dc_addrs: Vec<(i32, Vec<(IpAddr, u16)>)> = grouped_dc_addrs
                 .into_iter()
                 .map(|(dc, mut addrs)| {
                     addrs.sort_unstable();
                     addrs.dedup();
                     (dc, addrs)
                 })
+                .filter(|(_, addrs)| !addrs.is_empty())
                 .collect();
             dc_addrs.sort_unstable_by_key(|(dc, _)| *dc);
+            dc_addrs.sort_by_key(|(_, addrs)| (addrs.len() != 1, addrs.len()));
 
-            // Ensure at least one live writer per DC group; run missing DCs in parallel.
+            // Stage 1: build base coverage for conditional-cast.
+            // Single-endpoint DCs are prefilled first; multi-endpoint DCs require one live writer.
             let mut join = tokio::task::JoinSet::new();
             for (dc, addrs) in dc_addrs.iter().cloned() {
                 if addrs.is_empty() {
                     continue;
                 }
+                let target_writers = if addrs.len() == 1 {
+                    self.required_writers_for_dc_with_floor_mode(addrs.len(), false)
+                } else {
+                    1usize
+                };
                 let endpoints: HashSet<SocketAddr> = addrs
                     .iter()
                     .map(|(ip, port)| SocketAddr::new(*ip, *port))
                     .collect();
-                if self.active_writer_count_for_endpoints(&endpoints).await > 0 {
+                if self.active_writer_count_for_endpoints(&endpoints).await >= target_writers {
                     continue;
                 }
                 let pool = Arc::clone(self);
                 let rng_clone = Arc::clone(rng);
-                join.spawn(async move { pool.connect_primary_for_dc(dc, addrs, rng_clone).await });
+                join.spawn(async move {
+                    pool.connect_primary_for_dc(
+                        dc,
+                        addrs,
+                        target_writers,
+                        rng_clone,
+                        connect_concurrency,
+                    )
+                    .await
+                });
             }
             while join.join_next().await.is_some() {}
 
@@ -77,47 +89,35 @@ impl MePool {
                 )));
             }
 
-            // Warm reserve writers asynchronously so startup does not block after first working pool is ready.
+            // Stage 2: continue saturating multi-endpoint DC groups in background.
             let pool = Arc::clone(self);
             let rng_clone = Arc::clone(rng);
             let dc_addrs_bg = dc_addrs.clone();
             tokio::spawn(async move {
-                if pool.me_warmup_stagger_enabled {
+                let mut join_bg = tokio::task::JoinSet::new();
-                    for (dc, addrs) in &dc_addrs_bg {
+                for (dc, addrs) in dc_addrs_bg {
-                        for (ip, port) in addrs {
+                    if addrs.len() <= 1 {
-                            if pool.connection_count() >= pool_size {
+                        continue;
-                                break;
-                            }
-                            let addr = SocketAddr::new(*ip, *port);
-                            let jitter = rand::rng()
-                                .random_range(0..=pool.me_warmup_step_jitter.as_millis() as u64);
-                            let delay_ms = pool.me_warmup_step_delay.as_millis() as u64 + jitter;
-                            tokio::time::sleep(std::time::Duration::from_millis(delay_ms)).await;
-                            if let Err(e) = pool.connect_one(addr, rng_clone.as_ref()).await {
-                                debug!(%addr, dc = %dc, error = %e, "Extra ME connect failed (staggered)");
-                            }
-                        }
-                    }
-                } else {
-                    for (dc, addrs) in &dc_addrs_bg {
-                        for (ip, port) in addrs {
-                            if pool.connection_count() >= pool_size {
-                                break;
-                            }
-                            let addr = SocketAddr::new(*ip, *port);
-                            if let Err(e) = pool.connect_one(addr, rng_clone.as_ref()).await {
-                                debug!(%addr, dc = %dc, error = %e, "Extra ME connect failed");
-                            }
-                        }
-                        if pool.connection_count() >= pool_size {
-                            break;
-                        }
                     }
+                    let target_writers = pool.required_writers_for_dc_with_floor_mode(addrs.len(), false);
+                    let pool_clone = Arc::clone(&pool);
+                    let rng_clone_local = Arc::clone(&rng_clone);
+                    join_bg.spawn(async move {
+                        pool_clone
+                            .connect_primary_for_dc(
+                                dc,
+                                addrs,
+                                target_writers,
+                                rng_clone_local,
+                                connect_concurrency,
+                            )
+                            .await
+                    });
                 }
+                while join_bg.join_next().await.is_some() {}
                 debug!(
-                    target_pool_size = pool_size,
                     current_pool_size = pool.connection_count(),
-                    "Background ME reserve warmup finished"
+                    "Background ME saturation warmup finished"
                 );
             });
 
@@ -140,62 +140,85 @@ impl MePool {
         self: Arc<Self>,
         dc: i32,
         mut addrs: Vec<(IpAddr, u16)>,
+        target_writers: usize,
         rng: Arc<SecureRandom>,
+        connect_concurrency: usize,
     ) -> bool {
         if addrs.is_empty() {
             return false;
         }
+        let target_writers = target_writers.max(1);
         addrs.shuffle(&mut rand::rng());
-        if addrs.len() > 1 {
+        let endpoints: Vec<SocketAddr> = addrs
-            let concurrency = 2usize;
+            .iter()
+            .map(|(ip, port)| SocketAddr::new(*ip, *port))
+            .collect();
+        let endpoint_set: HashSet<SocketAddr> = endpoints.iter().copied().collect();
+
+        loop {
+            let alive = self.active_writer_count_for_endpoints(&endpoint_set).await;
+            if alive >= target_writers {
+                info!(
+                    dc = %dc,
+                    alive,
+                    target_writers,
+                    "ME connected"
+                );
+                return true;
+            }
+
+            let missing = target_writers.saturating_sub(alive).max(1);
+            let concurrency = connect_concurrency.max(1).min(missing);
             let mut join = tokio::task::JoinSet::new();
-            let mut next_idx = 0usize;
+            for _ in 0..concurrency {
+                let pool = Arc::clone(&self);
+                let rng_clone = Arc::clone(&rng);
+                let endpoints_clone = endpoints.clone();
+                join.spawn(async move {
+                    pool.connect_endpoints_round_robin(&endpoints_clone, rng_clone.as_ref())
+                        .await
+                });
+            }
 
-            while next_idx < addrs.len() || !join.is_empty() {
+            let mut progress = false;
-                while next_idx < addrs.len() && join.len() < concurrency {
+            while let Some(res) = join.join_next().await {
-                    let (ip, port) = addrs[next_idx];
-                    next_idx += 1;
-                    let addr = SocketAddr::new(ip, port);
-                    let pool = Arc::clone(&self);
-                    let rng_clone = Arc::clone(&rng);
-                    join.spawn(async move {
-                        (addr, pool.connect_one(addr, rng_clone.as_ref()).await)
-                    });
-                }
-
-                let Some(res) = join.join_next().await else {
-                    break;
-                };
                 match res {
-                    Ok((addr, Ok(()))) => {
+                    Ok(true) => {
-                        info!(%addr, dc = %dc, "ME connected");
+                        progress = true;
-                        join.abort_all();
-                        while join.join_next().await.is_some() {}
-                        return true;
-                    }
-                    Ok((addr, Err(e))) => {
-                        warn!(%addr, dc = %dc, error = %e, "ME connect failed, trying next");
                     }
+                    Ok(false) => {}
                     Err(e) => {
                         warn!(dc = %dc, error = %e, "ME connect task failed");
                     }
                 }
             }
-            warn!(dc = %dc, "All ME servers for DC failed at init");
-            return false;
-        }
 
-        for (ip, port) in addrs {
+            let alive_after = self.active_writer_count_for_endpoints(&endpoint_set).await;
-            let addr = SocketAddr::new(ip, port);
+            if alive_after >= target_writers {
-            match self.connect_one(addr, rng.as_ref()).await {
+                info!(
-                Ok(()) => {
+                    dc = %dc,
-                    info!(%addr, dc = %dc, "ME connected");
+                    alive = alive_after,
-                    return true;
+                    target_writers,
-                }
+                    "ME connected"
-                Err(e) => warn!(%addr, dc = %dc, error = %e, "ME connect failed, trying next"),
+                );
+                return true;
+            }
+            if !progress {
+                warn!(
+                    dc = %dc,
+                    alive = alive_after,
+                    target_writers,
+                    "All ME servers for DC failed at init"
+                );
+                return false;
+            }
+
+            if self.me_warmup_stagger_enabled {
+                let jitter = rand::rng()
+                    .random_range(0..=self.me_warmup_step_jitter.as_millis() as u64);
+                let delay_ms = self.me_warmup_step_delay.as_millis() as u64 + jitter;
+                tokio::time::sleep(std::time::Duration::from_millis(delay_ms)).await;
             }
         }
-        warn!(dc = %dc, "All ME servers for DC failed at init");
-        false
     }
 }

src/transport/middle_proxy/pool_nat.rs

@@ -248,6 +248,43 @@ impl MePool {
             }
         }
 
+        let _singleflight_guard = if use_shared_cache {
+            Some(match family {
+                IpFamily::V4 => self.nat_reflection_singleflight_v4.lock().await,
+                IpFamily::V6 => self.nat_reflection_singleflight_v6.lock().await,
+            })
+        } else {
+            None
+        };
+
+        if use_shared_cache
+            && let Some(until) = *self.stun_backoff_until.read().await
+            && Instant::now() < until
+        {
+            if let Ok(cache) = self.nat_reflection_cache.try_lock() {
+                let slot = match family {
+                    IpFamily::V4 => cache.v4,
+                    IpFamily::V6 => cache.v6,
+                };
+                return slot.map(|(_, addr)| addr);
+            }
+            return None;
+        }
+
+        if use_shared_cache
+            && let Ok(mut cache) = self.nat_reflection_cache.try_lock()
+        {
+            let slot = match family {
+                IpFamily::V4 => &mut cache.v4,
+                IpFamily::V6 => &mut cache.v6,
+            };
+            if let Some((ts, addr)) = slot
+                && ts.elapsed() < STUN_CACHE_TTL
+            {
+                return Some(*addr);
+            }
+        }
+
         let attempt = if use_shared_cache {
             self.nat_probe_attempts.fetch_add(1, std::sync::atomic::Ordering::Relaxed)
         } else {

src/transport/middle_proxy/pool_refill.rs

@@ -108,19 +108,10 @@ impl MePool {
         } else {
             IpFamily::V6
         };
-        let map = self.proxy_map_for_family(family).await;
+        Some(RefillDcKey {
-        for (dc, endpoints) in map {
+            dc: self.resolve_dc_for_endpoint(addr).await,
-            if endpoints
+            family,
-                .into_iter()
+        })
-                .any(|(ip, port)| SocketAddr::new(ip, port) == addr)
-            {
-                return Some(RefillDcKey {
-                    dc: dc.abs(),
-                    family,
-                });
-            }
-        }
-        None
     }
 
     async fn resolve_refill_dc_keys_for_endpoints(
@@ -177,47 +168,23 @@ impl MePool {
     }
 
     async fn endpoints_for_same_dc(&self, addr: SocketAddr) -> Vec<SocketAddr> {
-        let mut target_dc = HashSet::<i32>::new();
         let mut endpoints = HashSet::<SocketAddr>::new();
+        let target_dc = self.resolve_dc_for_endpoint(addr).await;
 
         if self.decision.ipv4_me {
             let map = self.proxy_map_v4.read().await.clone();
-            for (dc, addrs) in &map {
+            if let Some(addrs) = map.get(&target_dc) {
-                if addrs
+                for (ip, port) in addrs {
-                    .iter()
+                    endpoints.insert(SocketAddr::new(*ip, *port));
-                    .any(|(ip, port)| SocketAddr::new(*ip, *port) == addr)
-                {
-                    target_dc.insert(dc.abs());
-                }
-            }
-            for dc in &target_dc {
-                for key in [*dc, -*dc] {
-                    if let Some(addrs) = map.get(&key) {
-                        for (ip, port) in addrs {
-                            endpoints.insert(SocketAddr::new(*ip, *port));
-                        }
-                    }
                 }
             }
         }
 
         if self.decision.ipv6_me {
             let map = self.proxy_map_v6.read().await.clone();
-            for (dc, addrs) in &map {
+            if let Some(addrs) = map.get(&target_dc) {
-                if addrs
+                for (ip, port) in addrs {
-                    .iter()
+                    endpoints.insert(SocketAddr::new(*ip, *port));
-                    .any(|(ip, port)| SocketAddr::new(*ip, *port) == addr)
-                {
-                    target_dc.insert(dc.abs());
-                }
-            }
-            for dc in &target_dc {
-                for key in [*dc, -*dc] {
-                    if let Some(addrs) = map.get(&key) {
-                        for (ip, port) in addrs {
-                            endpoints.insert(SocketAddr::new(*ip, *port));
-                        }
-                    }
                 }
             }
         }

src/transport/middle_proxy/pool_reinit.rs

@@ -128,7 +128,7 @@ impl MePool {
         if self.decision.ipv4_me {
             let map_v4 = self.proxy_map_v4.read().await.clone();
             for (dc, addrs) in map_v4 {
-                let entry = out.entry(dc.abs()).or_default();
+                let entry = out.entry(dc).or_default();
                 for (ip, port) in addrs {
                     entry.insert(SocketAddr::new(ip, port));
                 }
@@ -138,7 +138,7 @@ impl MePool {
         if self.decision.ipv6_me {
             let map_v6 = self.proxy_map_v6.read().await.clone();
             for (dc, addrs) in map_v6 {
-                let entry = out.entry(dc.abs()).or_default();
+                let entry = out.entry(dc).or_default();
                 for (ip, port) in addrs {
                     entry.insert(SocketAddr::new(ip, port));
                 }

src/transport/middle_proxy/pool_runtime_api.rs

@@ -0,0 +1,128 @@
+use std::collections::HashMap;
+use std::time::Instant;
+
+use super::pool::{MePool, RefillDcKey};
+use crate::network::IpFamily;
+
+#[derive(Clone, Debug)]
+pub(crate) struct MeApiRefillDcSnapshot {
+    pub dc: i16,
+    pub family: &'static str,
+    pub inflight: usize,
+}
+
+#[derive(Clone, Debug)]
+pub(crate) struct MeApiRefillSnapshot {
+    pub inflight_endpoints_total: usize,
+    pub inflight_dc_total: usize,
+    pub by_dc: Vec<MeApiRefillDcSnapshot>,
+}
+
+#[derive(Clone, Debug)]
+pub(crate) struct MeApiNatReflectionSnapshot {
+    pub addr: std::net::SocketAddr,
+    pub age_secs: u64,
+}
+
+#[derive(Clone, Debug)]
+pub(crate) struct MeApiNatStunSnapshot {
+    pub nat_probe_enabled: bool,
+    pub nat_probe_disabled_runtime: bool,
+    pub nat_probe_attempts: u8,
+    pub configured_servers: Vec<String>,
+    pub live_servers: Vec<String>,
+    pub reflection_v4: Option<MeApiNatReflectionSnapshot>,
+    pub reflection_v6: Option<MeApiNatReflectionSnapshot>,
+    pub stun_backoff_remaining_ms: Option<u64>,
+}
+
+impl MePool {
+    pub(crate) async fn api_refill_snapshot(&self) -> MeApiRefillSnapshot {
+        let inflight_endpoints_total = self.refill_inflight.lock().await.len();
+        let inflight_dc_keys = self
+            .refill_inflight_dc
+            .lock()
+            .await
+            .iter()
+            .copied()
+            .collect::<Vec<RefillDcKey>>();
+
+        let mut by_dc_map = HashMap::<(i16, &'static str), usize>::new();
+        for key in inflight_dc_keys {
+            let family = match key.family {
+                IpFamily::V4 => "v4",
+                IpFamily::V6 => "v6",
+            };
+            let dc = key.dc as i16;
+            *by_dc_map.entry((dc, family)).or_insert(0) += 1;
+        }
+
+        let mut by_dc = by_dc_map
+            .into_iter()
+            .map(|((dc, family), inflight)| MeApiRefillDcSnapshot {
+                dc,
+                family,
+                inflight,
+            })
+            .collect::<Vec<_>>();
+        by_dc.sort_by_key(|entry| (entry.dc, entry.family));
+
+        MeApiRefillSnapshot {
+            inflight_endpoints_total,
+            inflight_dc_total: by_dc.len(),
+            by_dc,
+        }
+    }
+
+    pub(crate) async fn api_nat_stun_snapshot(&self) -> MeApiNatStunSnapshot {
+        let now = Instant::now();
+        let mut configured_servers = if !self.nat_stun_servers.is_empty() {
+            self.nat_stun_servers.clone()
+        } else if let Some(stun) = &self.nat_stun {
+            if stun.trim().is_empty() {
+                Vec::new()
+            } else {
+                vec![stun.clone()]
+            }
+        } else {
+            Vec::new()
+        };
+        configured_servers.sort();
+        configured_servers.dedup();
+
+        let mut live_servers = self.nat_stun_live_servers.read().await.clone();
+        live_servers.sort();
+        live_servers.dedup();
+
+        let reflection = self.nat_reflection_cache.lock().await;
+        let reflection_v4 = reflection.v4.map(|(ts, addr)| MeApiNatReflectionSnapshot {
+            addr,
+            age_secs: now.saturating_duration_since(ts).as_secs(),
+        });
+        let reflection_v6 = reflection.v6.map(|(ts, addr)| MeApiNatReflectionSnapshot {
+            addr,
+            age_secs: now.saturating_duration_since(ts).as_secs(),
+        });
+        drop(reflection);
+
+        let backoff_until = *self.stun_backoff_until.read().await;
+        let stun_backoff_remaining_ms = backoff_until.and_then(|until| {
+            (until > now).then_some(until.duration_since(now).as_millis() as u64)
+        });
+
+        MeApiNatStunSnapshot {
+            nat_probe_enabled: self.nat_probe,
+            nat_probe_disabled_runtime: self
+                .nat_probe_disabled
+                .load(std::sync::atomic::Ordering::Relaxed),
+            nat_probe_attempts: self
+                .nat_probe_attempts
+                .load(std::sync::atomic::Ordering::Relaxed),
+            configured_servers,
+            live_servers,
+            reflection_v4,
+            reflection_v6,
+            stun_backoff_remaining_ms,
+        }
+    }
+}

src/transport/middle_proxy/pool_status.rs

@@ -1,5 +1,5 @@
 use std::collections::{BTreeMap, BTreeSet, HashMap};
-use std::net::SocketAddr;
+use std::net::{IpAddr, SocketAddr};
 use std::sync::atomic::Ordering;
 use std::time::Instant;
 
@@ -100,47 +100,103 @@ pub(crate) struct MeApiRuntimeSnapshot {
 }
 
 impl MePool {
+    pub(crate) async fn admission_ready_conditional_cast(&self) -> bool {
+        let mut endpoints_by_dc = BTreeMap::<i16, BTreeSet<SocketAddr>>::new();
+        if self.decision.ipv4_me {
+            let map = self.proxy_map_v4.read().await.clone();
+            extend_signed_endpoints(&mut endpoints_by_dc, map);
+        }
+        if self.decision.ipv6_me {
+            let map = self.proxy_map_v6.read().await.clone();
+            extend_signed_endpoints(&mut endpoints_by_dc, map);
+        }
+
+        if endpoints_by_dc.is_empty() {
+            return false;
+        }
+
+        let writers = self.writers.read().await.clone();
+        let mut live_writers_by_endpoint = HashMap::<SocketAddr, usize>::new();
+        for writer in writers {
+            if writer.draining.load(Ordering::Relaxed) {
+                continue;
+            }
+            *live_writers_by_endpoint.entry(writer.addr).or_insert(0) += 1;
+        }
+
+        for endpoints in endpoints_by_dc.values() {
+            let alive: usize = endpoints
+                .iter()
+                .map(|endpoint| live_writers_by_endpoint.get(endpoint).copied().unwrap_or(0))
+                .sum();
+            if alive == 0 {
+                return false;
+            }
+        }
+
+        true
+    }
+
+    #[allow(dead_code)]
+    pub(crate) async fn admission_ready_full_floor(&self) -> bool {
+        let mut endpoints_by_dc = BTreeMap::<i16, BTreeSet<SocketAddr>>::new();
+        if self.decision.ipv4_me {
+            let map = self.proxy_map_v4.read().await.clone();
+            extend_signed_endpoints(&mut endpoints_by_dc, map);
+        }
+        if self.decision.ipv6_me {
+            let map = self.proxy_map_v6.read().await.clone();
+            extend_signed_endpoints(&mut endpoints_by_dc, map);
+        }
+
+        if endpoints_by_dc.is_empty() {
+            return false;
+        }
+
+        let writers = self.writers.read().await.clone();
+        let mut live_writers_by_endpoint = HashMap::<SocketAddr, usize>::new();
+        for writer in writers {
+            if writer.draining.load(Ordering::Relaxed) {
+                continue;
+            }
+            *live_writers_by_endpoint.entry(writer.addr).or_insert(0) += 1;
+        }
+
+        for endpoints in endpoints_by_dc.values() {
+            let endpoint_count = endpoints.len();
+            if endpoint_count == 0 {
+                return false;
+            }
+            let required = self.required_writers_for_dc_with_floor_mode(endpoint_count, false);
+            let alive: usize = endpoints
+                .iter()
+                .map(|endpoint| live_writers_by_endpoint.get(endpoint).copied().unwrap_or(0))
+                .sum();
+            if alive < required {
+                return false;
+            }
+        }
+
+        true
+    }
+
     pub(crate) async fn api_status_snapshot(&self) -> MeApiStatusSnapshot {
         let now_epoch_secs = Self::now_epoch_secs();
 
         let mut endpoints_by_dc = BTreeMap::<i16, BTreeSet<SocketAddr>>::new();
         if self.decision.ipv4_me {
             let map = self.proxy_map_v4.read().await.clone();
-            for (dc, addrs) in map {
+            extend_signed_endpoints(&mut endpoints_by_dc, map);
-                let abs_dc = dc.abs();
-                if abs_dc == 0 {
-                    continue;
-                }
-                let Ok(dc_idx) = i16::try_from(abs_dc) else {
-                    continue;
-                };
-                let entry = endpoints_by_dc.entry(dc_idx).or_default();
-                for (ip, port) in addrs {
-                    entry.insert(SocketAddr::new(ip, port));
-                }
-            }
         }
         if self.decision.ipv6_me {
             let map = self.proxy_map_v6.read().await.clone();
-            for (dc, addrs) in map {
+            extend_signed_endpoints(&mut endpoints_by_dc, map);
-                let abs_dc = dc.abs();
-                if abs_dc == 0 {
-                    continue;
-                }
-                let Ok(dc_idx) = i16::try_from(abs_dc) else {
-                    continue;
-                };
-                let entry = endpoints_by_dc.entry(dc_idx).or_default();
-                for (ip, port) in addrs {
-                    entry.insert(SocketAddr::new(ip, port));
-                }
-            }
         }
 
-        let mut endpoint_to_dc = HashMap::<SocketAddr, i16>::new();
+        let mut endpoint_to_dc = HashMap::<SocketAddr, BTreeSet<i16>>::new();
         for (dc, endpoints) in &endpoints_by_dc {
             for endpoint in endpoints {
-                endpoint_to_dc.entry(*endpoint).or_insert(*dc);
+                endpoint_to_dc.entry(*endpoint).or_default().insert(*dc);
             }
         }
 
@@ -164,7 +220,13 @@ impl MePool {
 
         for writer in writers {
             let endpoint = writer.addr;
-            let dc = endpoint_to_dc.get(&endpoint).copied();
+            let dc = endpoint_to_dc.get(&endpoint).and_then(|dcs| {
+                if dcs.len() == 1 {
+                    dcs.iter().next().copied()
+                } else {
+                    None
+                }
+            });
             let draining = writer.draining.load(Ordering::Relaxed);
             let degraded = writer.degraded.load(Ordering::Relaxed);
             let bound_clients = activity
@@ -371,6 +433,24 @@ fn ratio_pct(part: usize, total: usize) -> f64 {
     pct.clamp(0.0, 100.0)
 }
 
+fn extend_signed_endpoints(
+    endpoints_by_dc: &mut BTreeMap<i16, BTreeSet<SocketAddr>>,
+    map: HashMap<i32, Vec<(IpAddr, u16)>>,
+) {
+    for (dc, addrs) in map {
+        if dc == 0 {
+            continue;
+        }
+        let Ok(dc_idx) = i16::try_from(dc) else {
+            continue;
+        };
+        let entry = endpoints_by_dc.entry(dc_idx).or_default();
+        for (ip, port) in addrs {
+            entry.insert(SocketAddr::new(ip, port));
+        }
+    }
+}
+
 fn floor_mode_label(mode: MeFloorMode) -> &'static str {
     match mode {
         MeFloorMode::Static => "static",

src/transport/middle_proxy/reader.rs

@@ -124,7 +124,7 @@ pub(crate) async fn reader_loop(
                 let data = Bytes::copy_from_slice(&body[12..]);
                 trace!(cid, flags, len = data.len(), "RPC_PROXY_ANS");
 
-                let routed = reg.route(cid, MeResponse::Data { flags, data }).await;
+                let routed = reg.route_nowait(cid, MeResponse::Data { flags, data }).await;
                 if !matches!(routed, RouteResult::Routed) {
                     match routed {
                         RouteResult::NoConn => stats.increment_me_route_drop_no_conn(),
@@ -147,7 +147,7 @@ pub(crate) async fn reader_loop(
                 let cfm = u32::from_le_bytes(body[8..12].try_into().unwrap());
                 trace!(cid, cfm, "RPC_SIMPLE_ACK");
 
-                let routed = reg.route(cid, MeResponse::Ack(cfm)).await;
+                let routed = reg.route_nowait(cid, MeResponse::Ack(cfm)).await;
                 if !matches!(routed, RouteResult::Routed) {
                     match routed {
                         RouteResult::NoConn => stats.increment_me_route_drop_no_conn(),

src/transport/middle_proxy/registry.rs

@@ -208,6 +208,23 @@ impl ConnRegistry {
         }
     }
 
+    pub async fn route_nowait(&self, id: u64, resp: MeResponse) -> RouteResult {
+        let tx = {
+            let inner = self.inner.read().await;
+            inner.map.get(&id).cloned()
+        };
+
+        let Some(tx) = tx else {
+            return RouteResult::NoConn;
+        };
+
+        match tx.try_send(resp) {
+            Ok(()) => RouteResult::Routed,
+            Err(TrySendError::Closed(_)) => RouteResult::ChannelClosed,
+            Err(TrySendError::Full(_)) => RouteResult::QueueFullBase,
+        }
+    }
+
     pub async fn bind_writer(
         &self,
         conn_id: u64,
@@ -256,13 +273,12 @@ impl ConnRegistry {
             bound_clients_by_writer.insert(*writer_id, conn_ids.len());
         }
         for conn_meta in inner.meta.values() {
-            let dc_u16 = conn_meta.target_dc.unsigned_abs();
+            if conn_meta.target_dc == 0 {
-            if dc_u16 == 0 {
                 continue;
             }
-            if let Ok(dc) = i16::try_from(dc_u16) {
+            *active_sessions_by_target_dc
-                *active_sessions_by_target_dc.entry(dc).or_insert(0) += 1;
+                .entry(conn_meta.target_dc)
-            }
+                .or_insert(0) += 1;
         }
 
         WriterActivitySnapshot {
@@ -385,7 +401,8 @@ mod tests {
         let snapshot = registry.writer_activity_snapshot().await;
         assert_eq!(snapshot.bound_clients_by_writer.get(&10), Some(&2));
         assert_eq!(snapshot.bound_clients_by_writer.get(&20), Some(&1));
-        assert_eq!(snapshot.active_sessions_by_target_dc.get(&2), Some(&2));
+        assert_eq!(snapshot.active_sessions_by_target_dc.get(&2), Some(&1));
+        assert_eq!(snapshot.active_sessions_by_target_dc.get(&-2), Some(&1));
         assert_eq!(snapshot.active_sessions_by_target_dc.get(&4), Some(&1));
     }
 }

src/transport/middle_proxy/send.rs

@@ -22,6 +22,7 @@ use super::registry::ConnMeta;
 
 const IDLE_WRITER_PENALTY_MID_SECS: u64 = 45;
 const IDLE_WRITER_PENALTY_HIGH_SECS: u64 = 55;
+const HYBRID_GLOBAL_BURST_PERIOD_ROUNDS: u32 = 4;
 
 impl MePool {
     /// Send RPC_PROXY_REQ. `tag_override`: per-user ad_tag (from access.user_ad_tags); if None, uses pool default.
@@ -55,6 +56,9 @@ impl MePool {
         let mut no_writer_deadline: Option<Instant> = None;
         let mut emergency_attempts = 0u32;
         let mut async_recovery_triggered = false;
+        let mut hybrid_recovery_round = 0u32;
+        let mut hybrid_last_recovery_at: Option<Instant> = None;
+        let hybrid_wait_step = self.me_route_no_writer_wait.max(Duration::from_millis(50));
 
         loop {
             if let Some(current) = self.registry.get_writer(conn_id).await {
@@ -138,6 +142,18 @@ impl MePool {
                             }
                             continue;
                         }
+                        MeRouteNoWriterMode::HybridAsyncPersistent => {
+                            self.maybe_trigger_hybrid_recovery(
+                                target_dc,
+                                &mut hybrid_recovery_round,
+                                &mut hybrid_last_recovery_at,
+                                hybrid_wait_step,
+                            )
+                            .await;
+                            let deadline = Instant::now() + hybrid_wait_step;
+                            let _ = self.wait_for_writer_until(deadline).await;
+                            continue;
+                        }
                     }
                 }
                 ws.clone()
@@ -179,42 +195,41 @@ impl MePool {
                             return Err(ProxyError::Proxy("No ME writers available for target DC".into()));
                         }
                         emergency_attempts += 1;
-                        for family in self.family_order() {
+                        let mut endpoints = self.endpoint_candidates_for_target_dc(target_dc).await;
-                            let map_guard = match family {
+                        endpoints.shuffle(&mut rand::rng());
-                                IpFamily::V4 => self.proxy_map_v4.read().await,
+                        for addr in endpoints {
-                                IpFamily::V6 => self.proxy_map_v6.read().await,
+                            if self.connect_one(addr, self.rng.as_ref()).await.is_ok() {
-                            };
+                                break;
-                            if let Some(addrs) = map_guard.get(&(target_dc as i32)) {
-                                let mut shuffled = addrs.clone();
-                                shuffled.shuffle(&mut rand::rng());
-                                drop(map_guard);
-                                for (ip, port) in shuffled {
-                                    let addr = SocketAddr::new(ip, port);
-                                    if self.connect_one(addr, self.rng.as_ref()).await.is_ok() {
-                                        break;
-                                    }
-                                }
-                                tokio::time::sleep(Duration::from_millis(100 * emergency_attempts as u64)).await;
-                                let ws2 = self.writers.read().await;
-                                writers_snapshot = ws2.clone();
-                                drop(ws2);
-                                candidate_indices = self
-                                    .candidate_indices_for_dc(&writers_snapshot, target_dc, false)
-                                    .await;
-                                if candidate_indices.is_empty() {
-                                    candidate_indices = self
-                                        .candidate_indices_for_dc(&writers_snapshot, target_dc, true)
-                                        .await;
-                                }
-                                if !candidate_indices.is_empty() {
-                                    break;
-                                }
                             }
                         }
+                        tokio::time::sleep(Duration::from_millis(100 * emergency_attempts as u64)).await;
+                        let ws2 = self.writers.read().await;
+                        writers_snapshot = ws2.clone();
+                        drop(ws2);
+                        candidate_indices = self
+                            .candidate_indices_for_dc(&writers_snapshot, target_dc, false)
+                            .await;
+                        if candidate_indices.is_empty() {
+                            candidate_indices = self
+                                .candidate_indices_for_dc(&writers_snapshot, target_dc, true)
+                                .await;
+                        }
                         if candidate_indices.is_empty() {
                             return Err(ProxyError::Proxy("No ME writers available for target DC".into()));
                         }
                     }
+                    MeRouteNoWriterMode::HybridAsyncPersistent => {
+                        self.maybe_trigger_hybrid_recovery(
+                            target_dc,
+                            &mut hybrid_recovery_round,
+                            &mut hybrid_last_recovery_at,
+                            hybrid_wait_step,
+                        )
+                        .await;
+                        let deadline = Instant::now() + hybrid_wait_step;
+                        let _ = self.wait_for_candidate_until(target_dc, deadline).await;
+                        continue;
+                    }
                 }
             }
             let writer_idle_since = self.registry.writer_idle_since_snapshot().await;
@@ -430,26 +445,28 @@ impl MePool {
         let key = target_dc as i32;
         let mut preferred = Vec::<SocketAddr>::new();
         let mut seen = HashSet::<SocketAddr>::new();
+        let lookup_keys = self.dc_lookup_chain_for_target(key);
 
         for family in self.family_order() {
             let map = match family {
                 IpFamily::V4 => self.proxy_map_v4.read().await.clone(),
                 IpFamily::V6 => self.proxy_map_v6.read().await.clone(),
             };
-            let mut lookup_keys = vec![key, key.abs(), -key.abs()];
+            let mut family_selected = Vec::<SocketAddr>::new();
-            let def = self.default_dc.load(Ordering::Relaxed);
+            for lookup in lookup_keys.iter().copied() {
-            if def != 0 {
-                lookup_keys.push(def);
-            }
-            for lookup in lookup_keys {
                 if let Some(addrs) = map.get(&lookup) {
                     for (ip, port) in addrs {
-                        let addr = SocketAddr::new(*ip, *port);
+                        family_selected.push(SocketAddr::new(*ip, *port));
-                        if seen.insert(addr) {
-                            preferred.push(addr);
-                        }
                     }
                 }
+                if !family_selected.is_empty() {
+                    break;
+                }
+            }
+            for addr in family_selected {
+                if seen.insert(addr) {
+                    preferred.push(addr);
+                }
             }
             if !preferred.is_empty() && !self.decision.effective_multipath {
                 break;
@@ -459,6 +476,28 @@ impl MePool {
         preferred
     }
 
+    async fn maybe_trigger_hybrid_recovery(
+        self: &Arc<Self>,
+        target_dc: i16,
+        hybrid_recovery_round: &mut u32,
+        hybrid_last_recovery_at: &mut Option<Instant>,
+        hybrid_wait_step: Duration,
+    ) {
+        if let Some(last) = *hybrid_last_recovery_at
+            && last.elapsed() < hybrid_wait_step
+        {
+            return;
+        }
+
+        let round = *hybrid_recovery_round;
+        let target_triggered = self.trigger_async_recovery_for_target_dc(target_dc).await;
+        if !target_triggered || round % HYBRID_GLOBAL_BURST_PERIOD_ROUNDS == 0 {
+            self.trigger_async_recovery_global().await;
+        }
+        *hybrid_recovery_round = round.saturating_add(1);
+        *hybrid_last_recovery_at = Some(Instant::now());
+    }
+
     pub async fn send_close(self: &Arc<Self>, conn_id: u64) -> Result<()> {
         if let Some(w) = self.registry.get_writer(conn_id).await {
             let mut p = Vec::with_capacity(12);
@@ -519,36 +558,23 @@ impl MePool {
     ) -> Vec<usize> {
         let key = target_dc as i32;
         let mut preferred = Vec::<SocketAddr>::new();
+        let lookup_keys = self.dc_lookup_chain_for_target(key);
 
         for family in self.family_order() {
             let map_guard = match family {
                 IpFamily::V4 => self.proxy_map_v4.read().await,
                 IpFamily::V6 => self.proxy_map_v6.read().await,
             };
-
+            let mut family_selected = Vec::<SocketAddr>::new();
-            if let Some(v) = map_guard.get(&key) {
+            for lookup in lookup_keys.iter().copied() {
-                preferred.extend(v.iter().map(|(ip, port)| SocketAddr::new(*ip, *port)));
+                if let Some(v) = map_guard.get(&lookup) {
-            }
+                    family_selected.extend(v.iter().map(|(ip, port)| SocketAddr::new(*ip, *port)));
-            if preferred.is_empty() {
+                }
-                let abs = key.abs();
+                if !family_selected.is_empty() {
-                if let Some(v) = map_guard.get(&abs) {
+                    break;
-                    preferred.extend(v.iter().map(|(ip, port)| SocketAddr::new(*ip, *port)));
-                }
-            }
-            if preferred.is_empty() {
-                let abs = key.abs();
-                if let Some(v) = map_guard.get(&-abs) {
-                    preferred.extend(v.iter().map(|(ip, port)| SocketAddr::new(*ip, *port)));
-                }
-            }
-            if preferred.is_empty() {
-                let def = self.default_dc.load(Ordering::Relaxed);
-                if def != 0
-                    && let Some(v) = map_guard.get(&def)
-                {
-                    preferred.extend(v.iter().map(|(ip, port)| SocketAddr::new(*ip, *port)));
                 }
             }
+            preferred.extend(family_selected);
 
             drop(map_guard);
 
@@ -558,9 +584,7 @@ impl MePool {
         }
 
         if preferred.is_empty() {
-            return (0..writers.len())
+            return Vec::new();
-                .filter(|i| self.writer_eligible_for_selection(&writers[*i], include_warm))
-                .collect();
         }
 
         let mut out = Vec::new();
@@ -572,11 +596,6 @@ impl MePool {
                 out.push(idx);
             }
         }
-        if out.is_empty() {
-            return (0..writers.len())
-                .filter(|i| self.writer_eligible_for_selection(&writers[*i], include_warm))
-                .collect();
-        }
         out
     }
 

src/transport/upstream.rs

@@ -202,6 +202,15 @@ pub struct UpstreamApiSnapshot {
     pub upstreams: Vec<UpstreamApiItemSnapshot>,
 }
 
+#[derive(Debug, Clone, Copy)]
+pub struct UpstreamApiPolicySnapshot {
+    pub connect_retry_attempts: u32,
+    pub connect_retry_backoff_ms: u64,
+    pub connect_budget_ms: u64,
+    pub unhealthy_fail_threshold: u32,
+    pub connect_failfast_hard_errors: bool,
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct UpstreamEgressInfo {
     pub route_kind: UpstreamRouteKind,
@@ -225,6 +234,7 @@ pub struct UpstreamManager {
     upstreams: Arc<RwLock<Vec<UpstreamState>>>,
     connect_retry_attempts: u32,
     connect_retry_backoff: Duration,
+    connect_budget: Duration,
     unhealthy_fail_threshold: u32,
     connect_failfast_hard_errors: bool,
     stats: Arc<Stats>,
@@ -235,6 +245,7 @@ impl UpstreamManager {
         configs: Vec<UpstreamConfig>,
         connect_retry_attempts: u32,
         connect_retry_backoff_ms: u64,
+        connect_budget_ms: u64,
         unhealthy_fail_threshold: u32,
         connect_failfast_hard_errors: bool,
         stats: Arc<Stats>,
@@ -248,6 +259,7 @@ impl UpstreamManager {
             upstreams: Arc::new(RwLock::new(states)),
             connect_retry_attempts: connect_retry_attempts.max(1),
             connect_retry_backoff: Duration::from_millis(connect_retry_backoff_ms),
+            connect_budget: Duration::from_millis(connect_budget_ms.max(1)),
             unhealthy_fail_threshold: unhealthy_fail_threshold.max(1),
             connect_failfast_hard_errors,
             stats,
@@ -312,6 +324,16 @@ impl UpstreamManager {
         Some(UpstreamApiSnapshot { summary, upstreams })
     }
 
+    pub fn api_policy_snapshot(&self) -> UpstreamApiPolicySnapshot {
+        UpstreamApiPolicySnapshot {
+            connect_retry_attempts: self.connect_retry_attempts,
+            connect_retry_backoff_ms: self.connect_retry_backoff.as_millis() as u64,
+            connect_budget_ms: self.connect_budget.as_millis() as u64,
+            unhealthy_fail_threshold: self.unhealthy_fail_threshold,
+            connect_failfast_hard_errors: self.connect_failfast_hard_errors,
+        }
+    }
+
     #[cfg(unix)]
     fn resolve_interface_addrs(name: &str, want_ipv6: bool) -> Vec<IpAddr> {
         use nix::ifaddrs::getifaddrs;
@@ -593,11 +615,27 @@ impl UpstreamManager {
         let mut last_error: Option<ProxyError> = None;
         let mut attempts_used = 0u32;
         for attempt in 1..=self.connect_retry_attempts {
+            let elapsed = connect_started_at.elapsed();
+            if elapsed >= self.connect_budget {
+                last_error = Some(ProxyError::ConnectionTimeout {
+                    addr: target.to_string(),
+                });
+                break;
+            }
+            let remaining_budget = self.connect_budget.saturating_sub(elapsed);
+            let attempt_timeout = Duration::from_secs(DIRECT_CONNECT_TIMEOUT_SECS)
+                .min(remaining_budget);
+            if attempt_timeout.is_zero() {
+                last_error = Some(ProxyError::ConnectionTimeout {
+                    addr: target.to_string(),
+                });
+                break;
+            }
             attempts_used = attempt;
             self.stats.increment_upstream_connect_attempt_total();
             let start = Instant::now();
             match self
-                .connect_via_upstream(&upstream, target, bind_rr.clone())
+                .connect_via_upstream(&upstream, target, bind_rr.clone(), attempt_timeout)
                 .await
             {
                 Ok((stream, egress)) => {
@@ -707,6 +745,7 @@ impl UpstreamManager {
         config: &UpstreamConfig,
         target: SocketAddr,
         bind_rr: Option<Arc<AtomicUsize>>,
+        connect_timeout: Duration,
     ) -> Result<(TcpStream, UpstreamEgressInfo)> {
         match &config.upstream_type {
             UpstreamType::Direct { interface, bind_addresses } => {
@@ -735,7 +774,6 @@ impl UpstreamManager {
                 let std_stream: std::net::TcpStream = socket.into();
                 let stream = TcpStream::from_std(std_stream)?;
 
-                let connect_timeout = Duration::from_secs(DIRECT_CONNECT_TIMEOUT_SECS);
                 match tokio::time::timeout(connect_timeout, stream.writable()).await {
                     Ok(Ok(())) => {}
                     Ok(Err(e)) => return Err(ProxyError::Io(e)),
@@ -762,7 +800,6 @@ impl UpstreamManager {
                 ))
             },
             UpstreamType::Socks4 { address, interface, user_id } => {
-                let connect_timeout = Duration::from_secs(DIRECT_CONNECT_TIMEOUT_SECS);
                 // Try to parse as SocketAddr first (IP:port), otherwise treat as hostname:port
                 let mut stream = if let Ok(proxy_addr) = address.parse::<SocketAddr>() {
                     // IP:port format - use socket with optional interface binding
@@ -841,7 +878,6 @@ impl UpstreamManager {
                 ))
             },
             UpstreamType::Socks5 { address, interface, username, password } => {
-                let connect_timeout = Duration::from_secs(DIRECT_CONNECT_TIMEOUT_SECS);
                 // Try to parse as SocketAddr first (IP:port), otherwise treat as hostname:port
                 let mut stream = if let Ok(proxy_addr) = address.parse::<SocketAddr>() {
                     // IP:port format - use socket with optional interface binding
@@ -1165,7 +1201,14 @@ impl UpstreamManager {
         target: SocketAddr,
     ) -> Result<f64> {
         let start = Instant::now();
-        let _ = self.connect_via_upstream(config, target, bind_rr).await?;
+        let _ = self
+            .connect_via_upstream(
+                config,
+                target,
+                bind_rr,
+                Duration::from_secs(DC_PING_TIMEOUT_SECS),
+            )
+            .await?;
         Ok(start.elapsed().as_secs_f64() * 1000.0)
     }
 
@@ -1337,7 +1380,12 @@ impl UpstreamManager {
                             let start = Instant::now();
                             let result = tokio::time::timeout(
                                 Duration::from_secs(HEALTH_CHECK_CONNECT_TIMEOUT_SECS),
-                                self.connect_via_upstream(&config, endpoint, Some(bind_rr.clone())),
+                                self.connect_via_upstream(
+                                    &config,
+                                    endpoint,
+                                    Some(bind_rr.clone()),
+                                    Duration::from_secs(HEALTH_CHECK_CONNECT_TIMEOUT_SECS),
+                                ),
                             )
                             .await;