Merge pull request #338 from telemt/flow-api

API Zero + API Docs

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "telemt"
-version = "3.2.2"
+version = "3.3.4"
 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
@@ -118,8 +118,8 @@ We welcome ideas, architectural feedback, and pull requests.
 
 ## Quick Start Guide
 
-### [Quick Start Guid RU](docs/QUICK_START_GUIDE.ru.md)  
-### [Quick Start Guid EN](docs/QUICK_START_GUIDE.en.md)
+### [Quick Start Guide RU](docs/QUICK_START_GUIDE.ru.md)  
+### [Quick Start Guide EN](docs/QUICK_START_GUIDE.en.md)
 
 
 ### Advanced

docs/API.md

@@ -76,6 +76,10 @@ 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/stats/summary` | none | `200` | `SummaryData` |
 | `GET` | `/v1/stats/zero/all` | none | `200` | `ZeroAllData` |
 | `GET` | `/v1/stats/upstreams` | none | `200` | `UpstreamsData` |
@@ -176,6 +180,94 @@ 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`). |
+
 ### `ZeroAllData`
 | Field | Type | Description |
 | --- | --- | --- |

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/mod.rs

@@ -2,7 +2,8 @@ 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 std::time::{SystemTime, UNIX_EPOCH};
 
 use http_body_util::{BodyExt, Full};
 use hyper::body::{Bytes, Incoming};
@@ -25,6 +26,7 @@ use crate::transport::UpstreamManager;
 mod config_store;
 mod model;
 mod runtime_stats;
+mod runtime_zero;
 mod users;
 
 use config_store::{current_revision, parse_if_match};
@@ -36,8 +38,19 @@ 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 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>,
@@ -50,6 +63,7 @@ pub(super) struct ApiShared {
     pub(super) mutation_lock: Arc<Mutex<()>>,
     pub(super) minimal_cache: Arc<Mutex<Option<MinimalCacheEntry>>>,
     pub(super) request_id: Arc<AtomicU64>,
+    pub(super) runtime_state: Arc<ApiRuntimeState>,
 }
 
 impl ApiShared {
@@ -65,9 +79,11 @@ 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 +99,13 @@ 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,
@@ -94,6 +117,38 @@ pub async fn serve(
         mutation_lock: Arc::new(Mutex::new(())),
         minimal_cache: Arc::new(Mutex::new(None)),
         request_id: Arc::new(AtomicU64::new(1)),
+        runtime_state: runtime_state.clone(),
+    });
+
+    let mut config_rx_reload = config_rx.clone();
+    let runtime_state_reload = runtime_state.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);
+        }
+    });
+
+    let mut admission_rx_watch = admission_rx.clone();
+    tokio::spawn(async move {
+        runtime_state
+            .admission_open
+            .store(*admission_rx_watch.borrow(), Ordering::Relaxed);
+        loop {
+            if admission_rx_watch.changed().await.is_err() {
+                break;
+            }
+            runtime_state
+                .admission_open
+                .store(*admission_rx_watch.borrow(), Ordering::Relaxed);
+        }
     });
 
     loop {
@@ -189,6 +244,26 @@ 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/stats/summary") => {
                 let revision = current_revision(&shared.config_path).await?;
                 let data = SummaryData {
@@ -441,3 +516,10 @@ async fn read_body_with_limit(body: Incoming, limit: usize) -> Result<Vec<u8>, A
     }
     Ok(collected)
 }
+
+fn now_epoch_secs() -> u64 {
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_secs()
+}

src/api/model.rs

@@ -1,3 +1,5 @@
+use std::net::IpAddr;
+
 use chrono::{DateTime, Utc};
 use hyper::StatusCode;
 use rand::Rng;
@@ -369,6 +371,9 @@ pub(super) struct UserInfo {
     pub(super) max_unique_ips: Option<usize>,
     pub(super) current_connections: u64,
     pub(super) active_unique_ips: usize,
+    pub(super) active_unique_ips_list: Vec<IpAddr>,
+    pub(super) recent_unique_ips: usize,
+    pub(super) recent_unique_ips_list: Vec<IpAddr>,
     pub(super) total_octets: u64,
     pub(super) links: UserLinks,
 }

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/api/users.rs

@@ -1,4 +1,3 @@
-use std::collections::HashMap;
 use std::net::IpAddr;
 
 use hyper::StatusCode;
@@ -112,6 +111,9 @@ pub(super) async fn create_user(
             max_unique_ips: updated_limit,
             current_connections: 0,
             active_unique_ips: 0,
+            active_unique_ips_list: Vec::new(),
+            recent_unique_ips: 0,
+            recent_unique_ips_list: Vec::new(),
             total_octets: 0,
             links: build_user_links(
                 &cfg,
@@ -300,18 +302,21 @@ pub(super) async fn users_from_config(
     startup_detected_ip_v4: Option<IpAddr>,
     startup_detected_ip_v6: Option<IpAddr>,
 ) -> Vec<UserInfo> {
-    let ip_counts = ip_tracker
-        .get_stats()
-        .await
-        .into_iter()
-        .map(|(user, count, _)| (user, count))
-        .collect::<HashMap<_, _>>();
-
     let mut names = cfg.access.users.keys().cloned().collect::<Vec<_>>();
     names.sort();
+    let active_ip_lists = ip_tracker.get_active_ips_for_users(&names).await;
+    let recent_ip_lists = ip_tracker.get_recent_ips_for_users(&names).await;
 
     let mut users = Vec::with_capacity(names.len());
     for username in names {
+        let active_ip_list = active_ip_lists
+            .get(&username)
+            .cloned()
+            .unwrap_or_else(Vec::new);
+        let recent_ip_list = recent_ip_lists
+            .get(&username)
+            .cloned()
+            .unwrap_or_else(Vec::new);
         let links = cfg
             .access
             .users
@@ -340,7 +345,10 @@ pub(super) async fn users_from_config(
             data_quota_bytes: cfg.access.user_data_quota.get(&username).copied(),
             max_unique_ips: cfg.access.user_max_unique_ips.get(&username).copied(),
             current_connections: stats.get_user_curr_connects(&username),
-            active_unique_ips: ip_counts.get(&username).copied().unwrap_or(0),
+            active_unique_ips: active_ip_list.len(),
+            active_unique_ips_list: active_ip_list,
+            recent_unique_ips: recent_ip_list.len(),
+            recent_unique_ips_list: recent_ip_list,
             total_octets: stats.get_user_total_octets(&username),
             links,
             username,

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 +114,10 @@ pub(crate) fn default_api_minimal_runtime_cache_ttl_ms() -> u64 {
     1000
 }
 
+pub(crate) fn default_proxy_protocol_header_timeout_ms() -> u64 {
+    500
+}
+
 pub(crate) fn default_prefer_4() -> u8 {
     4
 }
@@ -129,6 +134,10 @@ pub(crate) fn default_unknown_dc_log_path() -> Option<String> {
     Some("unknown-dc.txt".to_string())
 }
 
+pub(crate) fn default_unknown_dc_file_log_enabled() -> bool {
+    false
+}
+
 pub(crate) fn default_pool_size() -> usize {
     8
 }
@@ -137,6 +146,14 @@ pub(crate) fn default_proxy_secret_path() -> Option<String> {
     Some("proxy-secret".to_string())
 }
 
+pub(crate) fn default_proxy_config_v4_cache_path() -> Option<String> {
+    Some("cache/proxy-config-v4.txt".to_string())
+}
+
+pub(crate) fn default_proxy_config_v6_cache_path() -> Option<String> {
+    Some("cache/proxy-config-v6.txt".to_string())
+}
+
 pub(crate) fn default_middle_proxy_nat_stun() -> Option<String> {
     None
 }
@@ -241,6 +258,10 @@ 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
 }
@@ -273,6 +294,18 @@ pub(crate) fn default_me_route_backpressure_high_watermark_pct() -> u8 {
     80
 }
 
+pub(crate) fn default_me_route_no_writer_wait_ms() -> u64 {
+    250
+}
+
+pub(crate) fn default_me_route_inline_recovery_attempts() -> u32 {
+    3
+}
+
+pub(crate) fn default_me_route_inline_recovery_wait_ms() -> u64 {
+    3000
+}
+
 pub(crate) fn default_beobachten_minutes() -> u64 {
     10
 }

src/config/hot_reload.rs

@@ -381,6 +381,22 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
         warned = true;
         warn!("config reload: general.middle_proxy_pool_size changed; restart required");
     }
+    if old.general.me_route_no_writer_mode != new.general.me_route_no_writer_mode
+        || old.general.me_route_no_writer_wait_ms != new.general.me_route_no_writer_wait_ms
+        || old.general.me_route_inline_recovery_attempts
+            != new.general.me_route_inline_recovery_attempts
+        || old.general.me_route_inline_recovery_wait_ms
+            != new.general.me_route_inline_recovery_wait_ms
+    {
+        warned = true;
+        warn!("config reload: general.me_route_no_writer_* changed; restart required");
+    }
+    if old.general.unknown_dc_log_path != new.general.unknown_dc_log_path
+        || old.general.unknown_dc_file_log_enabled != new.general.unknown_dc_file_log_enabled
+    {
+        warned = true;
+        warn!("config reload: general.unknown_dc_* changed; restart required");
+    }
     if old.general.me_init_retry_attempts != new.general.me_init_retry_attempts {
         warned = true;
         warn!("config reload: general.me_init_retry_attempts changed; restart required");
@@ -389,6 +405,12 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
         warned = true;
         warn!("config reload: general.me2dc_fallback changed; restart required");
     }
+    if old.general.proxy_config_v4_cache_path != new.general.proxy_config_v4_cache_path
+        || old.general.proxy_config_v6_cache_path != new.general.proxy_config_v6_cache_path
+    {
+        warned = true;
+        warn!("config reload: general.proxy_config_*_cache_path changed; restart required");
+    }
     if old.general.me_keepalive_enabled != new.general.me_keepalive_enabled
         || old.general.me_keepalive_interval_secs != new.general.me_keepalive_interval_secs
         || old.general.me_keepalive_jitter_secs != new.general.me_keepalive_jitter_secs

src/config/load.rs

@@ -203,6 +203,22 @@ impl ProxyConfig {
 
         sanitize_ad_tag(&mut config.general.ad_tag);
 
+        if let Some(path) = &config.general.proxy_config_v4_cache_path
+            && path.trim().is_empty()
+        {
+            return Err(ProxyError::Config(
+                "general.proxy_config_v4_cache_path cannot be empty when provided".to_string(),
+            ));
+        }
+
+        if let Some(path) = &config.general.proxy_config_v6_cache_path
+            && path.trim().is_empty()
+        {
+            return Err(ProxyError::Config(
+                "general.proxy_config_v6_cache_path cannot be empty when provided".to_string(),
+            ));
+        }
+
         if let Some(update_every) = config.general.update_every {
             if update_every == 0 {
                 return Err(ProxyError::Config(
@@ -249,6 +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(),
@@ -410,6 +432,24 @@ impl ProxyConfig {
             ));
         }
 
+        if !(10..=5000).contains(&config.general.me_route_no_writer_wait_ms) {
+            return Err(ProxyError::Config(
+                "general.me_route_no_writer_wait_ms must be within [10, 5000]".to_string(),
+            ));
+        }
+
+        if config.general.me_route_inline_recovery_attempts == 0 {
+            return Err(ProxyError::Config(
+                "general.me_route_inline_recovery_attempts must be > 0".to_string(),
+            ));
+        }
+
+        if !(10..=30000).contains(&config.general.me_route_inline_recovery_wait_ms) {
+            return Err(ProxyError::Config(
+                "general.me_route_inline_recovery_wait_ms must be within [10, 30000]".to_string(),
+            ));
+        }
+
         if config.server.api.request_body_limit_bytes == 0 {
             return Err(ProxyError::Config(
                 "server.api.request_body_limit_bytes must be > 0".to_string(),
@@ -428,6 +468,12 @@ impl ProxyConfig {
             ));
         }
 
+        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
@@ -509,10 +555,11 @@ 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.middle_proxy_nat_probe {
-            config.general.middle_proxy_nat_probe = true;
-            warn!("Auto-enabled middle_proxy_nat_probe for middle proxy mode");
+        if config.general.use_middle_proxy && !config.general.me_secret_atomic_snapshot {
+            config.general.me_secret_atomic_snapshot = true;
+            warn!(
+                "Auto-enabled me_secret_atomic_snapshot for middle proxy mode to keep KDF key_selector/secret coherent"
+            );
         }
 
         validate_network_cfg(&mut config.network)?;
@@ -673,6 +720,14 @@ mod tests {
             cfg.general.me2dc_fallback,
             default_me2dc_fallback()
         );
+        assert_eq!(
+            cfg.general.proxy_config_v4_cache_path,
+            default_proxy_config_v4_cache_path()
+        );
+        assert_eq!(
+            cfg.general.proxy_config_v6_cache_path,
+            default_proxy_config_v6_cache_path()
+        );
         assert_eq!(
             cfg.general.me_single_endpoint_shadow_writers,
             default_me_single_endpoint_shadow_writers()
@@ -783,6 +838,14 @@ mod tests {
             default_me_init_retry_attempts()
         );
         assert_eq!(general.me2dc_fallback, default_me2dc_fallback());
+        assert_eq!(
+            general.proxy_config_v4_cache_path,
+            default_proxy_config_v4_cache_path()
+        );
+        assert_eq!(
+            general.proxy_config_v6_cache_path,
+            default_proxy_config_v6_cache_path()
+        );
         assert_eq!(
             general.me_single_endpoint_shadow_writers,
             default_me_single_endpoint_shadow_writers()
@@ -1206,6 +1269,85 @@ mod tests {
         let _ = std::fs::remove_file(path_valid);
     }
 
+    #[test]
+    fn me_route_no_writer_wait_ms_out_of_range_is_rejected() {
+        let toml = r#"
+            [general]
+            me_route_no_writer_wait_ms = 5
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_me_route_no_writer_wait_ms_out_of_range_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let err = ProxyConfig::load(&path).unwrap_err().to_string();
+        assert!(err.contains("general.me_route_no_writer_wait_ms must be within [10, 5000]"));
+        let _ = std::fs::remove_file(path);
+    }
+
+    #[test]
+    fn me_route_no_writer_mode_is_parsed() {
+        let toml = r#"
+            [general]
+            me_route_no_writer_mode = "inline_recovery_legacy"
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_me_route_no_writer_mode_parse_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let cfg = ProxyConfig::load(&path).unwrap();
+        assert_eq!(
+            cfg.general.me_route_no_writer_mode,
+            crate::config::MeRouteNoWriterMode::InlineRecoveryLegacy
+        );
+        let _ = std::fs::remove_file(path);
+    }
+
+    #[test]
+    fn proxy_config_cache_paths_empty_are_rejected() {
+        let toml = r#"
+            [general]
+            proxy_config_v4_cache_path = "   "
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_proxy_config_v4_cache_path_empty_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let err = ProxyConfig::load(&path).unwrap_err().to_string();
+        assert!(err.contains("general.proxy_config_v4_cache_path cannot be empty"));
+        let _ = std::fs::remove_file(path);
+
+        let toml_v6 = r#"
+            [general]
+            proxy_config_v6_cache_path = ""
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let path_v6 = dir.join("telemt_proxy_config_v6_cache_path_empty_test.toml");
+        std::fs::write(&path_v6, toml_v6).unwrap();
+        let err_v6 = ProxyConfig::load(&path_v6).unwrap_err().to_string();
+        assert!(err_v6.contains("general.proxy_config_v6_cache_path cannot be empty"));
+        let _ = std::fs::remove_file(path_v6);
+    }
+
     #[test]
     fn me_hardswap_warmup_defaults_are_set() {
         let toml = r#"

src/config/types.rs

@@ -183,6 +183,35 @@ impl MeFloorMode {
     }
 }
 
+/// Middle-End route behavior when no writer is immediately available.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "snake_case")]
+pub enum MeRouteNoWriterMode {
+    AsyncRecoveryFailfast,
+    InlineRecoveryLegacy,
+    #[default]
+    HybridAsyncPersistent,
+}
+
+impl MeRouteNoWriterMode {
+    pub fn as_u8(self) -> u8 {
+        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,
+            2 => MeRouteNoWriterMode::HybridAsyncPersistent,
+            _ => MeRouteNoWriterMode::HybridAsyncPersistent,
+        }
+    }
+}
+
 /// Per-user unique source IP limit mode.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
 #[serde(rename_all = "snake_case")]
@@ -318,6 +347,14 @@ pub struct GeneralConfig {
     #[serde(default = "default_proxy_secret_path")]
     pub proxy_secret_path: Option<String>,
 
+    /// Optional path to cache raw getProxyConfig (IPv4) snapshot for startup fallback.
+    #[serde(default = "default_proxy_config_v4_cache_path")]
+    pub proxy_config_v4_cache_path: Option<String>,
+
+    /// Optional path to cache raw getProxyConfigV6 snapshot for startup fallback.
+    #[serde(default = "default_proxy_config_v6_cache_path")]
+    pub proxy_config_v6_cache_path: Option<String>,
+
     /// Global ad_tag (32 hex chars from @MTProxybot). Fallback when user has no per-user tag in access.user_ad_tags.
     #[serde(default)]
     pub ad_tag: Option<String>,
@@ -495,6 +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,
@@ -511,6 +552,10 @@ pub struct GeneralConfig {
     #[serde(default = "default_unknown_dc_log_path")]
     pub unknown_dc_log_path: Option<String>,
 
+    /// Enable unknown-DC file logging.
+    #[serde(default = "default_unknown_dc_file_log_enabled")]
+    pub unknown_dc_file_log_enabled: bool,
+
     #[serde(default)]
     pub log_level: LogLevel,
 
@@ -538,6 +583,22 @@ pub struct GeneralConfig {
     #[serde(default = "default_me_route_backpressure_high_watermark_pct")]
     pub me_route_backpressure_high_watermark_pct: u8,
 
+    /// ME route behavior when no writer is immediately available.
+    #[serde(default)]
+    pub me_route_no_writer_mode: MeRouteNoWriterMode,
+
+    /// Maximum wait time in milliseconds for async-recovery failfast mode.
+    #[serde(default = "default_me_route_no_writer_wait_ms")]
+    pub me_route_no_writer_wait_ms: u64,
+
+    /// Number of inline recovery attempts in legacy mode.
+    #[serde(default = "default_me_route_inline_recovery_attempts")]
+    pub me_route_inline_recovery_attempts: u32,
+
+    /// Maximum wait time in milliseconds for inline recovery in legacy mode.
+    #[serde(default = "default_me_route_inline_recovery_wait_ms")]
+    pub me_route_inline_recovery_wait_ms: u64,
+
     /// [general.links] — proxy link generation overrides.
     #[serde(default)]
     pub links: LinksConfig,
@@ -682,6 +743,8 @@ impl Default for GeneralConfig {
             use_middle_proxy: default_true(),
             ad_tag: None,
             proxy_secret_path: default_proxy_secret_path(),
+            proxy_config_v4_cache_path: default_proxy_config_v4_cache_path(),
+            proxy_config_v6_cache_path: default_proxy_config_v6_cache_path(),
             middle_proxy_nat_ip: None,
             middle_proxy_nat_probe: default_true(),
             middle_proxy_nat_stun: default_middle_proxy_nat_stun(),
@@ -715,10 +778,12 @@ 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,
             unknown_dc_log_path: default_unknown_dc_log_path(),
+            unknown_dc_file_log_enabled: default_unknown_dc_file_log_enabled(),
             log_level: LogLevel::Normal,
             disable_colors: false,
             telemetry: TelemetryConfig::default(),
@@ -726,6 +791,10 @@ impl Default for GeneralConfig {
             me_route_backpressure_base_timeout_ms: default_me_route_backpressure_base_timeout_ms(),
             me_route_backpressure_high_timeout_ms: default_me_route_backpressure_high_timeout_ms(),
             me_route_backpressure_high_watermark_pct: default_me_route_backpressure_high_watermark_pct(),
+            me_route_no_writer_mode: MeRouteNoWriterMode::default(),
+            me_route_no_writer_wait_ms: default_me_route_no_writer_wait_ms(),
+            me_route_inline_recovery_attempts: default_me_route_inline_recovery_attempts(),
+            me_route_inline_recovery_wait_ms: default_me_route_inline_recovery_wait_ms(),
             links: LinksConfig::default(),
             crypto_pending_buffer: default_crypto_pending_buffer(),
             max_client_frame: default_max_client_frame(),
@@ -898,6 +967,10 @@ 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>,
 
@@ -921,6 +994,7 @@ 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());
-            out[written..written + take].copy_from_slice(&inner.buffer[..take]);
-            inner.buffer.drain(..take);
+            let available = inner.buffer.len().saturating_sub(inner.buffer_start);
+            let take = (out.len() - written).min(available);
+            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/ip_tracker.rs

@@ -2,7 +2,7 @@
 
 #![allow(dead_code)]
 
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 use std::net::IpAddr;
 use std::sync::Arc;
 use std::time::{Duration, Instant};
@@ -13,7 +13,7 @@ use crate::config::UserMaxUniqueIpsMode;
 
 #[derive(Debug, Clone)]
 pub struct UserIpTracker {
-    active_ips: Arc<RwLock<HashMap<String, HashSet<IpAddr>>>>,
+    active_ips: Arc<RwLock<HashMap<String, HashMap<IpAddr, usize>>>>,
     recent_ips: Arc<RwLock<HashMap<String, HashMap<IpAddr, Instant>>>>,
     max_ips: Arc<RwLock<HashMap<String, usize>>>,
     limit_mode: Arc<RwLock<UserMaxUniqueIpsMode>>,
@@ -67,21 +67,14 @@ impl UserIpTracker {
             let max_ips = self.max_ips.read().await;
             max_ips.get(username).copied()
         };
+        let mode = *self.limit_mode.read().await;
+        let window = *self.limit_window.read().await;
+        let now = Instant::now();
 
         let mut active_ips = self.active_ips.write().await;
         let user_active = active_ips
             .entry(username.to_string())
-            .or_insert_with(HashSet::new);
-
-        if limit.is_none() {
-            user_active.insert(ip);
-            return Ok(());
-        }
-
-        let limit = limit.unwrap_or_default();
-        let mode = *self.limit_mode.read().await;
-        let window = *self.limit_window.read().await;
-        let now = Instant::now();
+            .or_insert_with(HashMap::new);
 
         let mut recent_ips = self.recent_ips.write().await;
         let user_recent = recent_ips
@@ -89,32 +82,35 @@ impl UserIpTracker {
             .or_insert_with(HashMap::new);
         Self::prune_recent(user_recent, now, window);
 
-        if user_active.contains(&ip) {
+        if let Some(count) = user_active.get_mut(&ip) {
+            *count = count.saturating_add(1);
             user_recent.insert(ip, now);
             return Ok(());
         }
 
-        let active_limit_reached = user_active.len() >= limit;
-        let recent_limit_reached = user_recent.len() >= limit;
-        let deny = match mode {
-            UserMaxUniqueIpsMode::ActiveWindow => active_limit_reached,
-            UserMaxUniqueIpsMode::TimeWindow => recent_limit_reached,
-            UserMaxUniqueIpsMode::Combined => active_limit_reached || recent_limit_reached,
-        };
+        if let Some(limit) = limit {
+            let active_limit_reached = user_active.len() >= limit;
+            let recent_limit_reached = user_recent.len() >= limit;
+            let deny = match mode {
+                UserMaxUniqueIpsMode::ActiveWindow => active_limit_reached,
+                UserMaxUniqueIpsMode::TimeWindow => recent_limit_reached,
+                UserMaxUniqueIpsMode::Combined => active_limit_reached || recent_limit_reached,
+            };
 
-        if deny {
-            return Err(format!(
-                "IP limit reached for user '{}': active={}/{} recent={}/{} mode={:?}",
-                username,
-                user_active.len(),
-                limit,
-                user_recent.len(),
-                limit,
-                mode
-            ));
+            if deny {
+                return Err(format!(
+                    "IP limit reached for user '{}': active={}/{} recent={}/{} mode={:?}",
+                    username,
+                    user_active.len(),
+                    limit,
+                    user_recent.len(),
+                    limit,
+                    mode
+                ));
+            }
         }
 
-        user_active.insert(ip);
+        user_active.insert(ip, 1);
         user_recent.insert(ip, now);
         Ok(())
     }
@@ -122,23 +118,73 @@ impl UserIpTracker {
     pub async fn remove_ip(&self, username: &str, ip: IpAddr) {
         let mut active_ips = self.active_ips.write().await;
         if let Some(user_ips) = active_ips.get_mut(username) {
-            user_ips.remove(&ip);
+            if let Some(count) = user_ips.get_mut(&ip) {
+                if *count > 1 {
+                    *count -= 1;
+                } else {
+                    user_ips.remove(&ip);
+                }
+            }
             if user_ips.is_empty() {
                 active_ips.remove(username);
             }
         }
-        drop(active_ips);
+    }
 
-        let mode = *self.limit_mode.read().await;
-        if matches!(mode, UserMaxUniqueIpsMode::ActiveWindow) {
-            let mut recent_ips = self.recent_ips.write().await;
-            if let Some(user_recent) = recent_ips.get_mut(username) {
-                user_recent.remove(&ip);
-                if user_recent.is_empty() {
-                    recent_ips.remove(username);
-                }
-            }
+    pub async fn get_recent_counts_for_users(&self, users: &[String]) -> HashMap<String, usize> {
+        let window = *self.limit_window.read().await;
+        let now = Instant::now();
+        let recent_ips = self.recent_ips.read().await;
+
+        let mut counts = HashMap::with_capacity(users.len());
+        for user in users {
+            let count = if let Some(user_recent) = recent_ips.get(user) {
+                user_recent
+                    .values()
+                    .filter(|seen_at| now.duration_since(**seen_at) <= window)
+                    .count()
+            } else {
+                0
+            };
+            counts.insert(user.clone(), count);
         }
+        counts
+    }
+
+    pub async fn get_active_ips_for_users(&self, users: &[String]) -> HashMap<String, Vec<IpAddr>> {
+        let active_ips = self.active_ips.read().await;
+        let mut out = HashMap::with_capacity(users.len());
+        for user in users {
+            let mut ips = active_ips
+                .get(user)
+                .map(|per_ip| per_ip.keys().copied().collect::<Vec<_>>())
+                .unwrap_or_else(Vec::new);
+            ips.sort();
+            out.insert(user.clone(), ips);
+        }
+        out
+    }
+
+    pub async fn get_recent_ips_for_users(&self, users: &[String]) -> HashMap<String, Vec<IpAddr>> {
+        let window = *self.limit_window.read().await;
+        let now = Instant::now();
+        let recent_ips = self.recent_ips.read().await;
+
+        let mut out = HashMap::with_capacity(users.len());
+        for user in users {
+            let mut ips = if let Some(user_recent) = recent_ips.get(user) {
+                user_recent
+                    .iter()
+                    .filter(|(_, seen_at)| now.duration_since(**seen_at) <= window)
+                    .map(|(ip, _)| *ip)
+                    .collect::<Vec<_>>()
+            } else {
+                Vec::new()
+            };
+            ips.sort();
+            out.insert(user.clone(), ips);
+        }
+        out
     }
 
     pub async fn get_active_ip_count(&self, username: &str) -> usize {
@@ -150,7 +196,7 @@ impl UserIpTracker {
         let active_ips = self.active_ips.read().await;
         active_ips
             .get(username)
-            .map(|ips| ips.iter().copied().collect())
+            .map(|ips| ips.keys().copied().collect())
             .unwrap_or_else(Vec::new)
     }
 
@@ -190,7 +236,7 @@ impl UserIpTracker {
         let active_ips = self.active_ips.read().await;
         active_ips
             .get(username)
-            .map(|ips| ips.contains(&ip))
+            .map(|ips| ips.contains_key(&ip))
             .unwrap_or(false)
     }
 
@@ -266,6 +312,26 @@ mod tests {
         assert_eq!(tracker.get_active_ip_count("test_user").await, 2);
     }
 
+    #[tokio::test]
+    async fn test_active_window_rejects_new_ip_and_keeps_existing_session() {
+        let tracker = UserIpTracker::new();
+        tracker.set_user_limit("test_user", 1).await;
+        tracker
+            .set_limit_policy(UserMaxUniqueIpsMode::ActiveWindow, 30)
+            .await;
+
+        let ip1 = test_ipv4(10, 10, 10, 1);
+        let ip2 = test_ipv4(10, 10, 10, 2);
+
+        assert!(tracker.check_and_add("test_user", ip1).await.is_ok());
+        assert!(tracker.is_ip_active("test_user", ip1).await);
+        assert!(tracker.check_and_add("test_user", ip2).await.is_err());
+
+        // Existing session remains active; only new unique IP is denied.
+        assert!(tracker.is_ip_active("test_user", ip1).await);
+        assert_eq!(tracker.get_active_ip_count("test_user").await, 1);
+    }
+
     #[tokio::test]
     async fn test_reconnection_from_same_ip() {
         let tracker = UserIpTracker::new();
@@ -278,6 +344,24 @@ mod tests {
         assert_eq!(tracker.get_active_ip_count("test_user").await, 1);
     }
 
+    #[tokio::test]
+    async fn test_same_ip_disconnect_keeps_active_while_other_session_alive() {
+        let tracker = UserIpTracker::new();
+        tracker.set_user_limit("test_user", 2).await;
+
+        let ip1 = test_ipv4(192, 168, 1, 1);
+
+        assert!(tracker.check_and_add("test_user", ip1).await.is_ok());
+        assert!(tracker.check_and_add("test_user", ip1).await.is_ok());
+        assert_eq!(tracker.get_active_ip_count("test_user").await, 1);
+
+        tracker.remove_ip("test_user", ip1).await;
+        assert_eq!(tracker.get_active_ip_count("test_user").await, 1);
+
+        tracker.remove_ip("test_user", ip1).await;
+        assert_eq!(tracker.get_active_ip_count("test_user").await, 0);
+    }
+
     #[tokio::test]
     async fn test_ip_removal() {
         let tracker = UserIpTracker::new();

src/main.rs

@@ -4,11 +4,11 @@
 
 use std::net::SocketAddr;
 use std::sync::Arc;
-use std::time::Duration;
+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)]
@@ -41,8 +41,9 @@ use crate::stats::telemetry::TelemetryPolicy;
 use crate::stats::{ReplayChecker, Stats};
 use crate::stream::BufferPool;
 use crate::transport::middle_proxy::{
-    MePool, fetch_proxy_config, run_me_ping, MePingFamily, MePingSample, MeReinitTrigger, format_sample_line,
-    format_me_route,
+    MePool, ProxyConfigData, fetch_proxy_config_with_raw, format_me_route, format_sample_line,
+    load_proxy_config_cache, run_me_ping, save_proxy_config_cache, MePingFamily, MePingSample,
+    MeReinitTrigger,
 };
 use crate::transport::{ListenOptions, UpstreamManager, create_listener, find_listener_processes};
 use crate::tls_front::TlsFrontCache;
@@ -172,8 +173,206 @@ async fn write_beobachten_snapshot(path: &str, payload: &str) -> std::io::Result
     tokio::fs::write(path, payload).await
 }
 
+fn unit_label(value: u64, singular: &'static str, plural: &'static str) -> &'static str {
+    if value == 1 { singular } else { plural }
+}
+
+fn format_uptime(total_secs: u64) -> String {
+    const SECS_PER_MINUTE: u64 = 60;
+    const SECS_PER_HOUR: u64 = 60 * SECS_PER_MINUTE;
+    const SECS_PER_DAY: u64 = 24 * SECS_PER_HOUR;
+    const SECS_PER_MONTH: u64 = 30 * SECS_PER_DAY;
+    const SECS_PER_YEAR: u64 = 12 * SECS_PER_MONTH;
+
+    let mut remaining = total_secs;
+    let years = remaining / SECS_PER_YEAR;
+    remaining %= SECS_PER_YEAR;
+    let months = remaining / SECS_PER_MONTH;
+    remaining %= SECS_PER_MONTH;
+    let days = remaining / SECS_PER_DAY;
+    remaining %= SECS_PER_DAY;
+    let hours = remaining / SECS_PER_HOUR;
+    remaining %= SECS_PER_HOUR;
+    let minutes = remaining / SECS_PER_MINUTE;
+    let seconds = remaining % SECS_PER_MINUTE;
+
+    let mut parts = Vec::new();
+    if total_secs > SECS_PER_YEAR {
+        parts.push(format!(
+            "{} {}",
+            years,
+            unit_label(years, "year", "years")
+        ));
+    }
+    if total_secs > SECS_PER_MONTH {
+        parts.push(format!(
+            "{} {}",
+            months,
+            unit_label(months, "month", "months")
+        ));
+    }
+    if total_secs > SECS_PER_DAY {
+        parts.push(format!(
+            "{} {}",
+            days,
+            unit_label(days, "day", "days")
+        ));
+    }
+    if total_secs > SECS_PER_HOUR {
+        parts.push(format!(
+            "{} {}",
+            hours,
+            unit_label(hours, "hour", "hours")
+        ));
+    }
+    if total_secs > SECS_PER_MINUTE {
+        parts.push(format!(
+            "{} {}",
+            minutes,
+            unit_label(minutes, "minute", "minutes")
+        ));
+    }
+    parts.push(format!(
+        "{} {}",
+        seconds,
+        unit_label(seconds, "second", "seconds")
+    ));
+
+    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>,
+    me2dc_fallback: bool,
+    label: &'static str,
+) -> Option<ProxyConfigData> {
+    loop {
+        match fetch_proxy_config_with_raw(url).await {
+            Ok((cfg, raw)) => {
+                if !cfg.map.is_empty() {
+                    if let Some(path) = cache_path
+                        && let Err(e) = save_proxy_config_cache(path, &raw).await
+                    {
+                        warn!(error = %e, path, snapshot = label, "Failed to store startup proxy-config cache");
+                    }
+                    return Some(cfg);
+                }
+
+                warn!(snapshot = label, url, "Startup proxy-config is empty; trying disk cache");
+                if let Some(path) = cache_path {
+                    match load_proxy_config_cache(path).await {
+                        Ok(cached) if !cached.map.is_empty() => {
+                            info!(
+                                snapshot = label,
+                                path,
+                                proxy_for_lines = cached.proxy_for_lines,
+                                "Loaded startup proxy-config from disk cache"
+                            );
+                            return Some(cached);
+                        }
+                        Ok(_) => {
+                            warn!(
+                                snapshot = label,
+                                path,
+                                "Startup proxy-config cache is empty; ignoring cache file"
+                            );
+                        }
+                        Err(cache_err) => {
+                            debug!(
+                                snapshot = label,
+                                path,
+                                error = %cache_err,
+                                "Startup proxy-config cache unavailable"
+                            );
+                        }
+                    }
+                }
+
+                if me2dc_fallback {
+                    error!(
+                        snapshot = label,
+                        "Startup proxy-config unavailable and no saved config found; falling back to direct mode"
+                    );
+                    return None;
+                }
+
+                warn!(
+                    snapshot = label,
+                    retry_in_secs = 2,
+                    "Startup proxy-config unavailable and no saved config found; retrying because me2dc_fallback=false"
+                );
+                tokio::time::sleep(Duration::from_secs(2)).await;
+            }
+            Err(fetch_err) => {
+                if let Some(path) = cache_path {
+                    match load_proxy_config_cache(path).await {
+                        Ok(cached) if !cached.map.is_empty() => {
+                            info!(
+                                snapshot = label,
+                                path,
+                                proxy_for_lines = cached.proxy_for_lines,
+                                "Loaded startup proxy-config from disk cache"
+                            );
+                            return Some(cached);
+                        }
+                        Ok(_) => {
+                            warn!(
+                                snapshot = label,
+                                path,
+                                "Startup proxy-config cache is empty; ignoring cache file"
+                            );
+                        }
+                        Err(cache_err) => {
+                            debug!(
+                                snapshot = label,
+                                path,
+                                error = %cache_err,
+                                "Startup proxy-config cache unavailable"
+                            );
+                        }
+                    }
+                }
+
+                if me2dc_fallback {
+                    error!(
+                        snapshot = label,
+                        error = %fetch_err,
+                        "Startup proxy-config unavailable and no cached data; falling back to direct mode"
+                    );
+                    return None;
+                }
+
+                warn!(
+                    snapshot = label,
+                    error = %fetch_err,
+                    retry_in_secs = 2,
+                    "Startup proxy-config unavailable; retrying because me2dc_fallback=false"
+                );
+                tokio::time::sleep(Duration::from_secs(2)).await;
+            }
+        }
+    }
+}
+
 #[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) {
@@ -269,6 +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(),
@@ -445,6 +645,7 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
 
     let me2dc_fallback = config.general.me2dc_fallback;
     let me_init_retry_attempts = config.general.me_init_retry_attempts;
+    let me_init_warn_after_attempts: u32 = 3;
     if use_middle_proxy && !decision.ipv4_me && !decision.ipv6_me {
         if me2dc_fallback {
             warn!("No usable IP family for Middle Proxy detected; falling back to direct DC");
@@ -484,189 +685,199 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
         // =============================================================
         let proxy_secret_path = config.general.proxy_secret_path.as_deref();
         let pool_size = config.general.middle_proxy_pool_size.max(1);
-        let mut init_attempt: u32 = 0;
-        loop {
-            init_attempt = init_attempt.saturating_add(1);
-
-            let proxy_secret = match crate::transport::middle_proxy::fetch_proxy_secret(
+        let proxy_secret = loop {
+            match crate::transport::middle_proxy::fetch_proxy_secret(
                 proxy_secret_path,
                 config.general.proxy_secret_len_max,
             )
             .await
             {
-                Ok(proxy_secret) => proxy_secret,
+                Ok(proxy_secret) => break Some(proxy_secret),
                 Err(e) => {
-                    let retries_limited = me2dc_fallback && me_init_retry_attempts > 0;
-                    if retries_limited && init_attempt >= me_init_retry_attempts {
+                    if me2dc_fallback {
                         error!(
                             error = %e,
-                            attempt = init_attempt,
-                            retry_limit = me_init_retry_attempts,
-                            "ME startup retries exhausted while loading proxy-secret; falling back to direct mode"
+                            "ME startup failed: proxy-secret is unavailable and no saved secret found; falling back to direct mode"
                         );
                         break None;
                     }
 
                     warn!(
                         error = %e,
-                        attempt = init_attempt,
-                        retry_limit = if me_init_retry_attempts == 0 {
-                            String::from("unlimited")
-                        } else {
-                            me_init_retry_attempts.to_string()
-                        },
-                        me2dc_fallback = me2dc_fallback,
                         retry_in_secs = 2,
-                        "Failed to fetch proxy-secret; retrying ME startup"
+                        "ME startup failed: proxy-secret is unavailable and no saved secret found; retrying because me2dc_fallback=false"
                     );
                     tokio::time::sleep(Duration::from_secs(2)).await;
-                    continue;
-                }
-            };
-
-            info!(
-                secret_len = proxy_secret.len(),
-                key_sig = format_args!(
-                    "0x{:08x}",
-                    if proxy_secret.len() >= 4 {
-                        u32::from_le_bytes([
-                            proxy_secret[0],
-                            proxy_secret[1],
-                            proxy_secret[2],
-                            proxy_secret[3],
-                        ])
-                    } else {
-                        0
-                    }
-                ),
-                "Proxy-secret loaded"
-            );
-
-            // Load ME config (v4/v6) + default DC
-            let mut cfg_v4 = fetch_proxy_config(
-                "https://core.telegram.org/getProxyConfig",
-            )
-            .await
-            .unwrap_or_default();
-            let mut cfg_v6 = fetch_proxy_config(
-                "https://core.telegram.org/getProxyConfigV6",
-            )
-            .await
-            .unwrap_or_default();
-
-            if cfg_v4.map.is_empty() {
-                cfg_v4.map = crate::protocol::constants::TG_MIDDLE_PROXIES_V4.clone();
-            }
-            if cfg_v6.map.is_empty() {
-                cfg_v6.map = crate::protocol::constants::TG_MIDDLE_PROXIES_V6.clone();
-            }
-
-            let pool = MePool::new(
-                proxy_tag.clone(),
-                proxy_secret,
-                config.general.middle_proxy_nat_ip,
-                me_nat_probe,
-                None,
-                config.network.stun_servers.clone(),
-                config.general.stun_nat_probe_concurrency,
-                probe.detected_ipv6,
-                config.timeouts.me_one_retry,
-                config.timeouts.me_one_timeout_ms,
-                cfg_v4.map.clone(),
-                cfg_v6.map.clone(),
-                cfg_v4.default_dc.or(cfg_v6.default_dc),
-                decision.clone(),
-                Some(upstream_manager.clone()),
-                rng.clone(),
-                stats.clone(),
-                config.general.me_keepalive_enabled,
-                config.general.me_keepalive_interval_secs,
-                config.general.me_keepalive_jitter_secs,
-                config.general.me_keepalive_payload_random,
-                config.general.rpc_proxy_req_every,
-                config.general.me_warmup_stagger_enabled,
-                config.general.me_warmup_step_delay_ms,
-                config.general.me_warmup_step_jitter_ms,
-                config.general.me_reconnect_max_concurrent_per_dc,
-                config.general.me_reconnect_backoff_base_ms,
-                config.general.me_reconnect_backoff_cap_ms,
-                config.general.me_reconnect_fast_retry_count,
-                config.general.me_single_endpoint_shadow_writers,
-                config.general.me_single_endpoint_outage_mode_enabled,
-                config.general.me_single_endpoint_outage_disable_quarantine,
-                config.general.me_single_endpoint_outage_backoff_min_ms,
-                config.general.me_single_endpoint_outage_backoff_max_ms,
-                config.general.me_single_endpoint_shadow_rotate_every_secs,
-                config.general.me_floor_mode,
-                config.general.me_adaptive_floor_idle_secs,
-                config.general.me_adaptive_floor_min_writers_single_endpoint,
-                config.general.me_adaptive_floor_recover_grace_secs,
-                config.general.hardswap,
-                config.general.me_pool_drain_ttl_secs,
-                config.general.effective_me_pool_force_close_secs(),
-                config.general.me_pool_min_fresh_ratio,
-                config.general.me_hardswap_warmup_delay_min_ms,
-                config.general.me_hardswap_warmup_delay_max_ms,
-                config.general.me_hardswap_warmup_extra_passes,
-                config.general.me_hardswap_warmup_pass_backoff_base_ms,
-                config.general.me_bind_stale_mode,
-                config.general.me_bind_stale_ttl_secs,
-                config.general.me_secret_atomic_snapshot,
-                config.general.me_deterministic_writer_sort,
-                config.general.me_socks_kdf_policy,
-                config.general.me_route_backpressure_base_timeout_ms,
-                config.general.me_route_backpressure_high_timeout_ms,
-                config.general.me_route_backpressure_high_watermark_pct,
-            );
-
-            match pool.init(pool_size, &rng).await {
-                Ok(()) => {
-                    info!(
-                        attempt = init_attempt,
-                        "Middle-End pool initialized successfully"
-                    );
-
-                    // Phase 4: Start health monitor
-                    let pool_clone = pool.clone();
-                    let rng_clone = rng.clone();
-                    let min_conns = pool_size;
-                    tokio::spawn(async move {
-                        crate::transport::middle_proxy::me_health_monitor(
-                            pool_clone, rng_clone, min_conns,
-                        )
-                        .await;
-                    });
-
-                    break Some(pool);
-                }
-                Err(e) => {
-                    let retries_limited = me2dc_fallback && me_init_retry_attempts > 0;
-                    if retries_limited && init_attempt >= me_init_retry_attempts {
-                        error!(
-                            error = %e,
-                            attempt = init_attempt,
-                            retry_limit = me_init_retry_attempts,
-                            "ME pool init retries exhausted; falling back to direct mode"
-                        );
-                        break None;
-                    }
-
-                    warn!(
-                        error = %e,
-                        attempt = init_attempt,
-                        retry_limit = if me_init_retry_attempts == 0 {
-                            String::from("unlimited")
-                        } else {
-                            me_init_retry_attempts.to_string()
-                        },
-                        me2dc_fallback = me2dc_fallback,
-                        retry_in_secs = 2,
-                        "ME pool is not ready yet; retrying startup initialization"
-                    );
-                    pool.reset_stun_state();
-                    tokio::time::sleep(Duration::from_secs(2)).await;
                 }
             }
+        };
+        match proxy_secret {
+            Some(proxy_secret) => {
+                info!(
+                    secret_len = proxy_secret.len(),
+                    key_sig = format_args!(
+                        "0x{:08x}",
+                        if proxy_secret.len() >= 4 {
+                            u32::from_le_bytes([
+                                proxy_secret[0],
+                                proxy_secret[1],
+                                proxy_secret[2],
+                                proxy_secret[3],
+                            ])
+                        } else {
+                            0
+                        }
+                    ),
+                    "Proxy-secret loaded"
+                );
+
+                let cfg_v4 = load_startup_proxy_config_snapshot(
+                    "https://core.telegram.org/getProxyConfig",
+                    config.general.proxy_config_v4_cache_path.as_deref(),
+                    me2dc_fallback,
+                    "getProxyConfig",
+                )
+                .await;
+                let cfg_v6 = load_startup_proxy_config_snapshot(
+                    "https://core.telegram.org/getProxyConfigV6",
+                    config.general.proxy_config_v6_cache_path.as_deref(),
+                    me2dc_fallback,
+                    "getProxyConfigV6",
+                )
+                .await;
+
+                if let (Some(cfg_v4), Some(cfg_v6)) = (cfg_v4, cfg_v6) {
+                    let pool = MePool::new(
+                        proxy_tag.clone(),
+                        proxy_secret,
+                        config.general.middle_proxy_nat_ip,
+                        me_nat_probe,
+                        None,
+                        config.network.stun_servers.clone(),
+                        config.general.stun_nat_probe_concurrency,
+                        probe.detected_ipv6,
+                        config.timeouts.me_one_retry,
+                        config.timeouts.me_one_timeout_ms,
+                        cfg_v4.map.clone(),
+                        cfg_v6.map.clone(),
+                        cfg_v4.default_dc.or(cfg_v6.default_dc),
+                        decision.clone(),
+                        Some(upstream_manager.clone()),
+                        rng.clone(),
+                        stats.clone(),
+                        config.general.me_keepalive_enabled,
+                        config.general.me_keepalive_interval_secs,
+                        config.general.me_keepalive_jitter_secs,
+                        config.general.me_keepalive_payload_random,
+                        config.general.rpc_proxy_req_every,
+                        config.general.me_warmup_stagger_enabled,
+                        config.general.me_warmup_step_delay_ms,
+                        config.general.me_warmup_step_jitter_ms,
+                        config.general.me_reconnect_max_concurrent_per_dc,
+                        config.general.me_reconnect_backoff_base_ms,
+                        config.general.me_reconnect_backoff_cap_ms,
+                        config.general.me_reconnect_fast_retry_count,
+                        config.general.me_single_endpoint_shadow_writers,
+                        config.general.me_single_endpoint_outage_mode_enabled,
+                        config.general.me_single_endpoint_outage_disable_quarantine,
+                        config.general.me_single_endpoint_outage_backoff_min_ms,
+                        config.general.me_single_endpoint_outage_backoff_max_ms,
+                        config.general.me_single_endpoint_shadow_rotate_every_secs,
+                        config.general.me_floor_mode,
+                        config.general.me_adaptive_floor_idle_secs,
+                        config.general.me_adaptive_floor_min_writers_single_endpoint,
+                        config.general.me_adaptive_floor_recover_grace_secs,
+                        config.general.hardswap,
+                        config.general.me_pool_drain_ttl_secs,
+                        config.general.effective_me_pool_force_close_secs(),
+                        config.general.me_pool_min_fresh_ratio,
+                        config.general.me_hardswap_warmup_delay_min_ms,
+                        config.general.me_hardswap_warmup_delay_max_ms,
+                        config.general.me_hardswap_warmup_extra_passes,
+                        config.general.me_hardswap_warmup_pass_backoff_base_ms,
+                        config.general.me_bind_stale_mode,
+                        config.general.me_bind_stale_ttl_secs,
+                        config.general.me_secret_atomic_snapshot,
+                        config.general.me_deterministic_writer_sort,
+                        config.general.me_socks_kdf_policy,
+                        config.general.me_route_backpressure_base_timeout_ms,
+                        config.general.me_route_backpressure_high_timeout_ms,
+                        config.general.me_route_backpressure_high_watermark_pct,
+                        config.general.me_route_no_writer_mode,
+                        config.general.me_route_no_writer_wait_ms,
+                        config.general.me_route_inline_recovery_attempts,
+                        config.general.me_route_inline_recovery_wait_ms,
+                    );
+
+                    let mut init_attempt: u32 = 0;
+                    loop {
+                        init_attempt = init_attempt.saturating_add(1);
+                        match pool.init(pool_size, &rng).await {
+                            Ok(()) => {
+                                info!(
+                                    attempt = init_attempt,
+                                    "Middle-End pool initialized successfully"
+                                );
+
+                                // Phase 4: Start health monitor
+                                let pool_clone = pool.clone();
+                                let rng_clone = rng.clone();
+                                let min_conns = pool_size;
+                                tokio::spawn(async move {
+                                    crate::transport::middle_proxy::me_health_monitor(
+                                        pool_clone, rng_clone, min_conns,
+                                    )
+                                    .await;
+                                });
+
+                                break Some(pool);
+                            }
+                            Err(e) => {
+                                let retries_limited = me2dc_fallback && me_init_retry_attempts > 0;
+                                if retries_limited && init_attempt >= me_init_retry_attempts {
+                                    error!(
+                                        error = %e,
+                                        attempt = init_attempt,
+                                        retry_limit = me_init_retry_attempts,
+                                        "ME pool init retries exhausted; falling back to direct mode"
+                                    );
+                                    break None;
+                                }
+
+                                let retry_limit = if !me2dc_fallback || me_init_retry_attempts == 0 {
+                                    String::from("unlimited")
+                                } else {
+                                    me_init_retry_attempts.to_string()
+                                };
+                                if init_attempt >= me_init_warn_after_attempts {
+                                    warn!(
+                                        error = %e,
+                                        attempt = init_attempt,
+                                        retry_limit = retry_limit,
+                                        me2dc_fallback = me2dc_fallback,
+                                        retry_in_secs = 2,
+                                        "ME pool is not ready yet; retrying startup initialization"
+                                    );
+                                } else {
+                                    info!(
+                                        error = %e,
+                                        attempt = init_attempt,
+                                        retry_limit = retry_limit,
+                                        me2dc_fallback = me2dc_fallback,
+                                        retry_in_secs = 2,
+                                        "ME pool startup warmup: retrying initialization"
+                                    );
+                                }
+                                pool.reset_stun_state();
+                                tokio::time::sleep(Duration::from_secs(2)).await;
+                            }
+                        }
+                    }
+                } else {
+                    None
+                }
+            }
+            None => None,
         }
     } else {
         None
@@ -847,6 +1058,19 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
 		}
 	}
 
+    let initialized_secs = process_started_at.elapsed().as_secs();
+    let second_suffix = if initialized_secs == 1 { "" } else { "s" };
+    info!("===================== Telegram Startup =====================");
+    info!(
+        "  DC/ME Initialized in {} second{}",
+        initialized_secs, second_suffix
+    );
+    info!("============================================================");
+
+    if let Some(ref pool) = me_pool {
+        pool.set_runtime_ready(true);
+    }
+
     // Background tasks
     let um_clone = upstream_manager.clone();
     let decision_clone = decision.clone();
@@ -1117,6 +1341,60 @@ 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)]
@@ -1150,6 +1428,7 @@ 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();
@@ -1165,6 +1444,10 @@ 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 {
@@ -1277,6 +1560,7 @@ 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;
@@ -1288,9 +1572,11 @@ 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;
             });
@@ -1299,6 +1585,7 @@ 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();
@@ -1312,6 +1599,10 @@ 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 {
@@ -1400,7 +1691,36 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
     }
 
     match signal::ctrl_c().await {
-        Ok(()) => info!("Shutting down..."),
+        Ok(()) => {
+            let shutdown_started_at = Instant::now();
+            info!("Shutting down...");
+            let uptime_secs = process_started_at.elapsed().as_secs();
+            info!("Uptime: {}", format_uptime(uptime_secs));
+            if let Some(pool) = &me_pool {
+                match tokio::time::timeout(
+                    Duration::from_secs(2),
+                    pool.shutdown_send_close_conn_all(),
+                )
+                .await
+                {
+                    Ok(total) => {
+                        info!(
+                            close_conn_sent = total,
+                            "ME shutdown: RPC_CLOSE_CONN broadcast completed"
+                        );
+                    }
+                    Err(_) => {
+                        warn!("ME shutdown: RPC_CLOSE_CONN broadcast timed out");
+                    }
+                }
+            }
+            let shutdown_secs = shutdown_started_at.elapsed().as_secs();
+            info!(
+                "Shutdown completed successfully in {} {}.",
+                shutdown_secs,
+                unit_label(shutdown_secs, "second", "seconds")
+            );
+        }
         Err(e) => error!("Signal error: {}", e),
     }
 

src/metrics.rs

@@ -1199,6 +1199,48 @@ async fn render_metrics(stats: &Stats, config: &ProxyConfig, ip_tracker: &UserIp
             0
         }
     );
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_no_writer_failfast_total ME route failfast errors due to missing writer in bounded wait window"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_no_writer_failfast_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_no_writer_failfast_total {}",
+        if me_allows_normal {
+            stats.get_me_no_writer_failfast_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_async_recovery_trigger_total Async ME recovery trigger attempts from route path"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_async_recovery_trigger_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_async_recovery_trigger_total {}",
+        if me_allows_normal {
+            stats.get_me_async_recovery_trigger_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_inline_recovery_total Legacy inline ME recovery attempts from route path"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_inline_recovery_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_inline_recovery_total {}",
+        if me_allows_normal {
+            stats.get_me_inline_recovery_total()
+        } else {
+            0
+        }
+    );
 
     let unresolved_writer_losses = if me_allows_normal {
         stats
@@ -1237,6 +1279,29 @@ async fn render_metrics(stats: &Stats, config: &ProxyConfig, ip_tracker: &UserIp
     let _ = writeln!(out, "# TYPE telemt_user_msgs_from_client counter");
     let _ = writeln!(out, "# HELP telemt_user_msgs_to_client Per-user messages sent");
     let _ = writeln!(out, "# TYPE telemt_user_msgs_to_client counter");
+    let _ = writeln!(
+        out,
+        "# HELP telemt_ip_reservation_rollback_total IP reservation rollbacks caused by later limit checks"
+    );
+    let _ = writeln!(out, "# TYPE telemt_ip_reservation_rollback_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_ip_reservation_rollback_total{{reason=\"tcp_limit\"}} {}",
+        if core_enabled {
+            stats.get_ip_reservation_rollback_tcp_limit_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "telemt_ip_reservation_rollback_total{{reason=\"quota_limit\"}} {}",
+        if core_enabled {
+            stats.get_ip_reservation_rollback_quota_limit_total()
+        } else {
+            0
+        }
+    );
     let _ = writeln!(
         out,
         "# HELP telemt_telemetry_user_series_suppressed User-labeled metric series suppression flag"
@@ -1267,11 +1332,21 @@ async fn render_metrics(stats: &Stats, config: &ProxyConfig, ip_tracker: &UserIp
             .collect();
 
         let mut unique_users = BTreeSet::new();
+        unique_users.extend(config.access.users.keys().cloned());
         unique_users.extend(config.access.user_max_unique_ips.keys().cloned());
         unique_users.extend(ip_counts.keys().cloned());
+        let unique_users_vec: Vec<String> = unique_users.iter().cloned().collect();
+        let recent_counts = ip_tracker
+            .get_recent_counts_for_users(&unique_users_vec)
+            .await;
 
         let _ = writeln!(out, "# HELP telemt_user_unique_ips_current Per-user current number of unique active IPs");
         let _ = writeln!(out, "# TYPE telemt_user_unique_ips_current gauge");
+        let _ = writeln!(
+            out,
+            "# HELP telemt_user_unique_ips_recent_window Per-user unique IPs seen in configured observation window"
+        );
+        let _ = writeln!(out, "# TYPE telemt_user_unique_ips_recent_window gauge");
         let _ = writeln!(out, "# HELP telemt_user_unique_ips_limit Per-user configured unique IP limit (0 means unlimited)");
         let _ = writeln!(out, "# TYPE telemt_user_unique_ips_limit gauge");
         let _ = writeln!(out, "# HELP telemt_user_unique_ips_utilization Per-user unique IP usage ratio (0 for unlimited)");
@@ -1286,6 +1361,12 @@ async fn render_metrics(stats: &Stats, config: &ProxyConfig, ip_tracker: &UserIp
                 0.0
             };
             let _ = writeln!(out, "telemt_user_unique_ips_current{{user=\"{}\"}} {}", user, current);
+            let _ = writeln!(
+                out,
+                "telemt_user_unique_ips_recent_window{{user=\"{}\"}} {}",
+                user,
+                recent_counts.get(&user).copied().unwrap_or(0)
+            );
             let _ = writeln!(out, "telemt_user_unique_ips_limit{{user=\"{}\"}} {}", user, limit);
             let _ = writeln!(
                 out,
@@ -1378,6 +1459,7 @@ mod tests {
         assert!(output.contains("telemt_user_msgs_from_client{user=\"alice\"} 1"));
         assert!(output.contains("telemt_user_msgs_to_client{user=\"alice\"} 2"));
         assert!(output.contains("telemt_user_unique_ips_current{user=\"alice\"} 1"));
+        assert!(output.contains("telemt_user_unique_ips_recent_window{user=\"alice\"} 1"));
         assert!(output.contains("telemt_user_unique_ips_limit{user=\"alice\"} 4"));
         assert!(output.contains("telemt_user_unique_ips_utilization{user=\"alice\"} 0.250000"));
     }
@@ -1391,7 +1473,8 @@ mod tests {
         assert!(output.contains("telemt_connections_total 0"));
         assert!(output.contains("telemt_connections_bad_total 0"));
         assert!(output.contains("telemt_handshake_timeouts_total 0"));
-        assert!(!output.contains("user="));
+        assert!(output.contains("telemt_user_unique_ips_current{user="));
+        assert!(output.contains("telemt_user_unique_ips_recent_window{user="));
     }
 
     #[tokio::test]
@@ -1412,6 +1495,7 @@ mod tests {
             "# TYPE telemt_me_writer_removed_unexpected_minus_restored_total gauge"
         ));
         assert!(output.contains("# TYPE telemt_user_unique_ips_current gauge"));
+        assert!(output.contains("# TYPE telemt_user_unique_ips_recent_window gauge"));
         assert!(output.contains("# TYPE telemt_user_unique_ips_limit gauge"));
         assert!(output.contains("# TYPE telemt_user_unique_ips_utilization gauge"));
     }

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 {
-            Ok(info) => {
+        let proxy_header_timeout = Duration::from_millis(
+            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 {
-                Ok(info) => {
+            let proxy_header_timeout = Duration::from_millis(
+                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
         {
@@ -672,42 +706,16 @@ impl RunningClientHandler {
         R: AsyncRead + Unpin + Send + 'static,
         W: AsyncWrite + Unpin + Send + 'static,
     {
-        let user = &success.user;
+        let user = success.user.clone();
 
-        if let Err(e) = Self::check_user_limits_static(user, &config, &stats, peer_addr, &ip_tracker).await {
+        if let Err(e) = Self::check_user_limits_static(&user, &config, &stats, peer_addr, &ip_tracker).await {
             warn!(user = %user, error = %e, "User limit exceeded");
             return Err(e);
         }
 
-        // IP Cleanup Guard: автоматически удаляет IP при выходе из scope
-        struct IpCleanupGuard {
-            tracker: Arc<UserIpTracker>,
-            user: String,
-            ip: std::net::IpAddr,
-        }
-        
-        impl Drop for IpCleanupGuard {
-            fn drop(&mut self) {
-                let tracker = self.tracker.clone();
-                let user = self.user.clone();
-                let ip = self.ip;
-                tokio::spawn(async move {
-                    tracker.remove_ip(&user, ip).await;
-                    debug!(user = %user, ip = %ip, "IP cleaned up on disconnect");
-                });
-            }
-        }
-        
-        let _cleanup = IpCleanupGuard {
-            tracker: ip_tracker,
-            user: user.clone(),
-            ip: peer_addr.ip(),
-        };
-
-        // Decide: middle proxy or direct
-        if config.general.use_middle_proxy {
+        let relay_result = if config.general.use_middle_proxy {
             if let Some(ref pool) = me_pool {
-                return handle_via_middle_proxy(
+                handle_via_middle_proxy(
                     client_reader,
                     client_writer,
                     success,
@@ -718,23 +726,38 @@ impl RunningClientHandler {
                     local_addr,
                     rng,
                 )
-                .await;
+                .await
+            } else {
+                warn!("use_middle_proxy=true but MePool not initialized, falling back to direct");
+                handle_via_direct(
+                    client_reader,
+                    client_writer,
+                    success,
+                    upstream_manager,
+                    stats,
+                    config,
+                    buffer_pool,
+                    rng,
+                )
+                .await
             }
-            warn!("use_middle_proxy=true but MePool not initialized, falling back to direct");
-        }
+        } else {
+            // Direct mode (original behavior)
+            handle_via_direct(
+                client_reader,
+                client_writer,
+                success,
+                upstream_manager,
+                stats,
+                config,
+                buffer_pool,
+                rng,
+            )
+            .await
+        };
 
-        // Direct mode (original behavior)
-        handle_via_direct(
-            client_reader,
-            client_writer,
-            success,
-            upstream_manager,
-            stats,
-            config,
-            buffer_pool,
-            rng,
-        )
-        .await
+        ip_tracker.remove_ip(&user, peer_addr.ip()).await;
+        relay_result
     }
 
     async fn check_user_limits_static(
@@ -752,22 +775,32 @@ impl RunningClientHandler {
             });
         }
 
+        let mut ip_reserved = false;
         // IP limit check
-        if let Err(reason) = ip_tracker.check_and_add(user, peer_addr.ip()).await {
-            warn!(
-                user = %user,
-                ip = %peer_addr.ip(),
-                reason = %reason,
-                "IP limit exceeded"
-            );
-            return Err(ProxyError::ConnectionLimitExceeded {
-                user: user.to_string(),
-            });
+        match ip_tracker.check_and_add(user, peer_addr.ip()).await {
+            Ok(()) => {
+                ip_reserved = true;
+            }
+            Err(reason) => {
+                warn!(
+                    user = %user,
+                    ip = %peer_addr.ip(),
+                    reason = %reason,
+                    "IP limit exceeded"
+                );
+                return Err(ProxyError::ConnectionLimitExceeded {
+                    user: user.to_string(),
+                });
+            }
         }
 
         if let Some(limit) = config.access.user_max_tcp_conns.get(user)
             && stats.get_user_curr_connects(user) >= *limit as u64
         {
+            if ip_reserved {
+                ip_tracker.remove_ip(user, peer_addr.ip()).await;
+                stats.increment_ip_reservation_rollback_tcp_limit_total();
+            }
             return Err(ProxyError::ConnectionLimitExceeded {
                 user: user.to_string(),
             });
@@ -776,6 +809,10 @@ impl RunningClientHandler {
         if let Some(quota) = config.access.user_data_quota.get(user)
             && stats.get_user_total_octets(user) >= *quota
         {
+            if ip_reserved {
+                ip_tracker.remove_ip(user, peer_addr.ip()).await;
+                stats.increment_ip_reservation_rollback_quota_limit_total();
+            }
             return Err(ProxyError::DataQuotaExceeded {
                 user: user.to_string(),
             });

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,
@@ -118,10 +118,16 @@ fn get_dc_addr_static(dc_idx: i16, config: &ProxyConfig) -> Result<SocketAddr> {
     // Unknown DC requested by client without override: log and fall back.
     if !config.dc_overrides.contains_key(&dc_key) {
         warn!(dc_idx = dc_idx, "Requested non-standard DC with no override; falling back to default cluster");
-        if let Some(path) = &config.general.unknown_dc_log_path
-            && let Ok(mut file) = OpenOptions::new().create(true).append(true).open(path)
+        if config.general.unknown_dc_file_log_enabled
+            && let Some(path) = &config.general.unknown_dc_log_path
+            && let Ok(handle) = tokio::runtime::Handle::try_current()
         {
-            let _ = writeln!(file, "dc_idx={dc_idx}");
+            let path = path.clone();
+            handle.spawn_blocking(move || {
+                if let Ok(mut file) = OpenOptions::new().create(true).append(true).open(path) {
+                    let _ = writeln!(file, "dc_idx={dc_idx}");
+                }
+            });
         }
     }
 

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()
-        .filter_map(|(name, hex)| {
-            hex::decode(hex).ok().map(|bytes| (name.clone(), bytes))
-        })
-        .collect();
+    let secrets = decode_user_secrets(config, None);
 
     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 secret = match hex::decode(secret_hex) {
-            Ok(s) => s,
-            Err(_) => continue,
-        };
+    let decoded_users = decode_user_secrets(config, preferred_user);
+
+    for (user, secret) in decoded_users {
 
         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,

src/stats/mod.rs

@@ -100,6 +100,11 @@ pub struct Stats {
     me_refill_failed_total: AtomicU64,
     me_writer_restored_same_endpoint_total: AtomicU64,
     me_writer_restored_fallback_total: AtomicU64,
+    me_no_writer_failfast_total: AtomicU64,
+    me_async_recovery_trigger_total: AtomicU64,
+    me_inline_recovery_total: AtomicU64,
+    ip_reservation_rollback_tcp_limit_total: AtomicU64,
+    ip_reservation_rollback_quota_limit_total: AtomicU64,
     telemetry_core_enabled: AtomicBool,
     telemetry_user_enabled: AtomicBool,
     telemetry_me_level: AtomicU8,
@@ -522,6 +527,34 @@ impl Stats {
                 .fetch_add(1, Ordering::Relaxed);
         }
     }
+    pub fn increment_me_no_writer_failfast_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_no_writer_failfast_total.fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_async_recovery_trigger_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_async_recovery_trigger_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_inline_recovery_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_inline_recovery_total.fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_ip_reservation_rollback_tcp_limit_total(&self) {
+        if self.telemetry_core_enabled() {
+            self.ip_reservation_rollback_tcp_limit_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_ip_reservation_rollback_quota_limit_total(&self) {
+        if self.telemetry_core_enabled() {
+            self.ip_reservation_rollback_quota_limit_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
     pub fn increment_me_endpoint_quarantine_total(&self) {
         if self.telemetry_me_allows_normal() {
             self.me_endpoint_quarantine_total
@@ -791,21 +824,52 @@ impl Stats {
     pub fn get_me_writer_restored_fallback_total(&self) -> u64 {
         self.me_writer_restored_fallback_total.load(Ordering::Relaxed)
     }
+    pub fn get_me_no_writer_failfast_total(&self) -> u64 {
+        self.me_no_writer_failfast_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_async_recovery_trigger_total(&self) -> u64 {
+        self.me_async_recovery_trigger_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_inline_recovery_total(&self) -> u64 {
+        self.me_inline_recovery_total.load(Ordering::Relaxed)
+    }
+    pub fn get_ip_reservation_rollback_tcp_limit_total(&self) -> u64 {
+        self.ip_reservation_rollback_tcp_limit_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_ip_reservation_rollback_quota_limit_total(&self) -> u64 {
+        self.ip_reservation_rollback_quota_limit_total
+            .load(Ordering::Relaxed)
+    }
     
     pub fn increment_user_connects(&self, user: &str) {
         if !self.telemetry_user_enabled() {
             return;
         }
-        self.user_stats.entry(user.to_string()).or_default()
-            .connects.fetch_add(1, Ordering::Relaxed);
+        if let Some(stats) = self.user_stats.get(user) {
+            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()
-            .curr_connects.fetch_add(1, Ordering::Relaxed);
+        if let Some(stats) = self.user_stats.get(user) {
+            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) {
@@ -839,32 +903,60 @@ impl Stats {
         if !self.telemetry_user_enabled() {
             return;
         }
-        self.user_stats.entry(user.to_string()).or_default()
-            .octets_from_client.fetch_add(bytes, Ordering::Relaxed);
+        if let Some(stats) = self.user_stats.get(user) {
+            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()
-            .octets_to_client.fetch_add(bytes, Ordering::Relaxed);
+        if let Some(stats) = self.user_stats.get(user) {
+            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()
-            .msgs_from_client.fetch_add(1, Ordering::Relaxed);
+        if let Some(stats) = self.user_stats.get(user) {
+            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()
-            .msgs_to_client.fetch_add(1, Ordering::Relaxed);
+        if let Some(stats) = self.user_stats.get(user) {
+            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/config_updater.rs

@@ -1,6 +1,7 @@
 use std::collections::HashMap;
 use std::hash::{DefaultHasher, Hash, Hasher};
 use std::net::IpAddr;
+use std::path::Path;
 use std::sync::Arc;
 use std::time::Duration;
 
@@ -42,6 +43,87 @@ pub struct ProxyConfigData {
     pub proxy_for_lines: u32,
 }
 
+pub fn parse_proxy_config_text(text: &str, http_status: u16) -> ProxyConfigData {
+    let mut map: HashMap<i32, Vec<(IpAddr, u16)>> = HashMap::new();
+    let mut proxy_for_lines: u32 = 0;
+    for line in text.lines() {
+        if let Some((dc, ip, port)) = parse_proxy_line(line) {
+            map.entry(dc).or_default().push((ip, port));
+            proxy_for_lines = proxy_for_lines.saturating_add(1);
+        }
+    }
+
+    let default_dc = text.lines().find_map(|l| {
+        let t = l.trim();
+        if let Some(rest) = t.strip_prefix("default") {
+            return rest.trim().trim_end_matches(';').parse::<i32>().ok();
+        }
+        None
+    });
+
+    ProxyConfigData {
+        map,
+        default_dc,
+        http_status,
+        proxy_for_lines,
+    }
+}
+
+pub async fn load_proxy_config_cache(path: &str) -> Result<ProxyConfigData> {
+    let text = tokio::fs::read_to_string(path).await.map_err(|e| {
+        crate::error::ProxyError::Proxy(format!("read proxy-config cache '{path}' failed: {e}"))
+    })?;
+    Ok(parse_proxy_config_text(&text, 200))
+}
+
+pub async fn save_proxy_config_cache(path: &str, raw_text: &str) -> Result<()> {
+    if let Some(parent) = Path::new(path).parent()
+        && !parent.as_os_str().is_empty()
+    {
+        tokio::fs::create_dir_all(parent).await.map_err(|e| {
+            crate::error::ProxyError::Proxy(format!(
+                "create proxy-config cache dir '{}' failed: {e}",
+                parent.display()
+            ))
+        })?;
+    }
+
+    tokio::fs::write(path, raw_text).await.map_err(|e| {
+        crate::error::ProxyError::Proxy(format!("write proxy-config cache '{path}' failed: {e}"))
+    })?;
+    Ok(())
+}
+
+pub async fn fetch_proxy_config_with_raw(url: &str) -> Result<(ProxyConfigData, String)> {
+    let resp = reqwest::get(url)
+        .await
+        .map_err(|e| crate::error::ProxyError::Proxy(format!("fetch_proxy_config GET failed: {e}")))?
+        ;
+    let http_status = resp.status().as_u16();
+
+    if let Some(date) = resp.headers().get(reqwest::header::DATE)
+        && let Ok(date_str) = date.to_str()
+        && let Ok(server_time) = httpdate::parse_http_date(date_str)
+        && let Ok(skew) = SystemTime::now().duration_since(server_time).or_else(|e| {
+            server_time.duration_since(SystemTime::now()).map_err(|_| e)
+        })
+    {
+        let skew_secs = skew.as_secs();
+        if skew_secs > 60 {
+            warn!(skew_secs, "Time skew >60s detected from fetch_proxy_config Date header");
+        } else if skew_secs > 30 {
+            warn!(skew_secs, "Time skew >30s detected from fetch_proxy_config Date header");
+        }
+    }
+
+    let text = resp
+        .text()
+        .await
+        .map_err(|e| crate::error::ProxyError::Proxy(format!("fetch_proxy_config read failed: {e}")))?;
+    let parsed = parse_proxy_config_text(&text, http_status);
+    Ok((parsed, text))
+}
+
 #[derive(Debug, Default)]
 struct StableSnapshot {
     candidate_hash: Option<u64>,
@@ -170,61 +252,9 @@ fn parse_proxy_line(line: &str) -> Option<(i32, IpAddr, u16)> {
 }
 
 pub async fn fetch_proxy_config(url: &str) -> Result<ProxyConfigData> {
-    let resp = reqwest::get(url)
+    fetch_proxy_config_with_raw(url)
         .await
-        .map_err(|e| crate::error::ProxyError::Proxy(format!("fetch_proxy_config GET failed: {e}")))?
-        ;
-    let http_status = resp.status().as_u16();
-
-    if let Some(date) = resp.headers().get(reqwest::header::DATE)
-        && let Ok(date_str) = date.to_str()
-        && let Ok(server_time) = httpdate::parse_http_date(date_str)
-        && let Ok(skew) = SystemTime::now().duration_since(server_time).or_else(|e| {
-            server_time.duration_since(SystemTime::now()).map_err(|_| e)
-        })
-    {
-        let skew_secs = skew.as_secs();
-        if skew_secs > 60 {
-            warn!(skew_secs, "Time skew >60s detected from fetch_proxy_config Date header");
-        } else if skew_secs > 30 {
-            warn!(skew_secs, "Time skew >30s detected from fetch_proxy_config Date header");
-        }
-    }
-
-    let text = resp
-        .text()
-        .await
-        .map_err(|e| crate::error::ProxyError::Proxy(format!("fetch_proxy_config read failed: {e}")))?;
-
-    let mut map: HashMap<i32, Vec<(IpAddr, u16)>> = HashMap::new();
-    let mut proxy_for_lines: u32 = 0;
-    for line in text.lines() {
-        if let Some((dc, ip, port)) = parse_proxy_line(line) {
-            map.entry(dc).or_default().push((ip, port));
-            proxy_for_lines = proxy_for_lines.saturating_add(1);
-        }
-    }
-
-    let default_dc = text
-        .lines()
-        .find_map(|l| {
-            let t = l.trim();
-            if let Some(rest) = t.strip_prefix("default") {
-                return rest
-                    .trim()
-                    .trim_end_matches(';')
-                    .parse::<i32>()
-                    .ok();
-            }
-            None
-        });
-
-    Ok(ProxyConfigData {
-        map,
-        default_dc,
-        http_status,
-        proxy_for_lines,
-    })
+        .map(|(parsed, _raw)| parsed)
 }
 
 fn snapshot_passes_guards(

src/transport/middle_proxy/handshake.rs

@@ -387,9 +387,11 @@ impl MePool {
             socks_bound_addr.map(|value| value.ip()),
             client_port_source,
         );
-        let mut kdf_fingerprint_guard = self.kdf_material_fingerprint.lock().await;
-        if let Some((prev_fingerprint, prev_client_port)) =
+        let previous_kdf_fingerprint = {
+            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 +418,9 @@ 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

@@ -295,15 +295,27 @@ async fn check_family(
             let wait = Duration::from_millis(next_ms)
                 + Duration::from_millis(rand::rng().random_range(0..=jitter.max(1)));
             next_attempt.insert(key, now + wait);
-            warn!(
-                dc = %dc,
-                ?family,
-                alive = now_alive,
-                required,
-                endpoint_count = endpoints.len(),
-                backoff_ms = next_ms,
-                "DC writer floor is below required level, scheduled reconnect"
-            );
+            if pool.is_runtime_ready() {
+                warn!(
+                    dc = %dc,
+                    ?family,
+                    alive = now_alive,
+                    required,
+                    endpoint_count = endpoints.len(),
+                    backoff_ms = next_ms,
+                    "DC writer floor is below required level, scheduled reconnect"
+                );
+            } else {
+                info!(
+                    dc = %dc,
+                    ?family,
+                    alive = now_alive,
+                    required,
+                    endpoint_count = endpoints.len(),
+                    backoff_ms = next_ms,
+                    "DC writer floor is below required level during startup, scheduled reconnect"
+                );
+            }
         }
         if let Some(v) = inflight.get_mut(&key) {
             *v = v.saturating_sub(1);

src/transport/middle_proxy/mod.rs

@@ -30,7 +30,11 @@ pub use pool::MePool;
 pub use pool_nat::{stun_probe, detect_public_ip};
 pub use registry::ConnRegistry;
 pub use secret::fetch_proxy_secret;
-pub use config_updater::{fetch_proxy_config, me_config_updater};
+#[allow(unused_imports)]
+pub use config_updater::{
+    ProxyConfigData, fetch_proxy_config, fetch_proxy_config_with_raw, load_proxy_config_cache,
+    me_config_updater, save_proxy_config_cache,
+};
 pub use rotation::{MeReinitTrigger, me_reinit_scheduler, me_rotation_task};
 pub use wire::proto_flags_for_tag;
 

src/transport/middle_proxy/pool.rs

@@ -7,7 +7,7 @@ use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 use tokio::sync::{Mutex, Notify, RwLock, mpsc};
 use tokio_util::sync::CancellationToken;
 
-use crate::config::{MeBindStaleMode, MeFloorMode, MeSocksKdfPolicy};
+use crate::config::{MeBindStaleMode, MeFloorMode, MeRouteNoWriterMode, MeSocksKdfPolicy};
 use crate::crypto::SecureRandom;
 use crate::network::IpFamily;
 use crate::network::probe::NetworkDecision;
@@ -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,
@@ -145,6 +147,11 @@ pub struct MePool {
     pub(super) secret_atomic_snapshot: AtomicBool,
     pub(super) me_deterministic_writer_sort: AtomicBool,
     pub(super) me_socks_kdf_policy: AtomicU8,
+    pub(super) me_route_no_writer_mode: AtomicU8,
+    pub(super) me_route_no_writer_wait: Duration,
+    pub(super) me_route_inline_recovery_attempts: u32,
+    pub(super) me_route_inline_recovery_wait: Duration,
+    pub(super) runtime_ready: AtomicBool,
     pool_size: usize,
 }
 
@@ -227,6 +234,10 @@ impl MePool {
         me_route_backpressure_base_timeout_ms: u64,
         me_route_backpressure_high_timeout_ms: u64,
         me_route_backpressure_high_watermark_pct: u8,
+        me_route_no_writer_mode: MeRouteNoWriterMode,
+        me_route_no_writer_wait_ms: u64,
+        me_route_inline_recovery_attempts: u32,
+        me_route_inline_recovery_wait_ms: u64,
     ) -> Arc<Self> {
         let registry = Arc::new(ConnRegistry::new());
         registry.update_route_backpressure_policy(
@@ -314,6 +325,8 @@ impl MePool {
             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())),
@@ -326,7 +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(
@@ -343,6 +356,11 @@ impl MePool {
             secret_atomic_snapshot: AtomicBool::new(me_secret_atomic_snapshot),
             me_deterministic_writer_sort: AtomicBool::new(me_deterministic_writer_sort),
             me_socks_kdf_policy: AtomicU8::new(me_socks_kdf_policy.as_u8()),
+            me_route_no_writer_mode: AtomicU8::new(me_route_no_writer_mode.as_u8()),
+            me_route_no_writer_wait: Duration::from_millis(me_route_no_writer_wait_ms),
+            me_route_inline_recovery_attempts,
+            me_route_inline_recovery_wait: Duration::from_millis(me_route_inline_recovery_wait_ms),
+            runtime_ready: AtomicBool::new(false),
         })
     }
 
@@ -350,6 +368,14 @@ impl MePool {
         self.active_generation.load(Ordering::Relaxed)
     }
 
+    pub fn set_runtime_ready(&self, ready: bool) {
+        self.runtime_ready.store(ready, Ordering::Relaxed);
+    }
+
+    pub fn is_runtime_ready(&self) -> bool {
+        self.runtime_ready.load(Ordering::Relaxed)
+    }
+
     pub fn update_runtime_reinit_policy(
         &self,
         hardswap: bool,

src/transport/middle_proxy/pool_init.rs

@@ -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"
@@ -41,23 +43,39 @@ impl MePool {
                 })
                 .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 +95,35 @@ 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 {
-                    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);
-                            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 mut join_bg = tokio::task::JoinSet::new();
+                for (dc, addrs) in dc_addrs_bg {
+                    if addrs.len() <= 1 {
+                        continue;
                     }
+                    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 +146,85 @@ 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 concurrency = 2usize;
+        let endpoints: Vec<SocketAddr> = addrs
+            .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() {
-                while next_idx < addrs.len() && join.len() < concurrency {
-                    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;
-                };
+            let mut progress = false;
+            while let Some(res) = join.join_next().await {
                 match res {
-                    Ok((addr, Ok(()))) => {
-                        info!(%addr, dc = %dc, "ME connected");
-                        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(true) => {
+                        progress = true;
                     }
+                    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 addr = SocketAddr::new(ip, port);
-            match self.connect_one(addr, rng.as_ref()).await {
-                Ok(()) => {
-                    info!(%addr, dc = %dc, "ME connected");
-                    return true;
-                }
-                Err(e) => warn!(%addr, dc = %dc, error = %e, "ME connect failed, trying next"),
+            let alive_after = self.active_writer_count_for_endpoints(&endpoint_set).await;
+            if alive_after >= target_writers {
+                info!(
+                    dc = %dc,
+                    alive = alive_after,
+                    target_writers,
+                    "ME connected"
+                );
+                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_status.rs

@@ -100,6 +100,134 @@ 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();
+            for (dc, addrs) in 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 {
+                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 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();
+            for (dc, addrs) in 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 {
+                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 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();
 

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,
@@ -278,6 +295,11 @@ impl ConnRegistry {
         Some(ConnWriter { writer_id, tx: writer })
     }
 
+    pub async fn active_conn_ids(&self) -> Vec<u64> {
+        let inner = self.inner.read().await;
+        inner.writer_for_conn.keys().copied().collect()
+    }
+
     pub async fn writer_lost(&self, writer_id: u64) -> Vec<BoundConn> {
         let mut inner = self.inner.write().await;
         inner.writers.remove(&writer_id);

src/transport/middle_proxy/send.rs

@@ -1,16 +1,17 @@
 use std::cmp::Reverse;
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 use std::net::SocketAddr;
 use std::sync::Arc;
 use std::sync::atomic::Ordering;
-use std::time::Duration;
+use std::time::{Duration, Instant};
 
 use tokio::sync::mpsc::error::TrySendError;
 use tracing::{debug, warn};
 
+use crate::config::MeRouteNoWriterMode;
 use crate::error::{ProxyError, Result};
 use crate::network::IpFamily;
-use crate::protocol::constants::RPC_CLOSE_EXT_U32;
+use crate::protocol::constants::{RPC_CLOSE_CONN_U32, RPC_CLOSE_EXT_U32};
 
 use super::MePool;
 use super::codec::WriterCommand;
@@ -21,6 +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.
@@ -49,7 +51,14 @@ impl MePool {
             our_addr,
             proto_flags,
         };
-        let mut emergency_attempts = 0;
+        let no_writer_mode =
+            MeRouteNoWriterMode::from_u8(self.me_route_no_writer_mode.load(Ordering::Relaxed));
+        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 {
@@ -74,34 +83,78 @@ impl MePool {
             let mut writers_snapshot = {
                 let ws = self.writers.read().await;
                 if ws.is_empty() {
-                    // Create waiter before recovery attempts so notify_one permits are not missed.
-                    let waiter = self.writer_available.notified();
                     drop(ws);
-                    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(),
-                        };
-                        for (_dc, addrs) in map.iter() {
-                            for (ip, port) in addrs {
-                                let addr = SocketAddr::new(*ip, *port);
-                                if self.connect_one(addr, self.rng.as_ref()).await.is_ok() {
-                                    self.writer_available.notify_one();
+                    match no_writer_mode {
+                        MeRouteNoWriterMode::AsyncRecoveryFailfast => {
+                            let deadline = *no_writer_deadline.get_or_insert_with(|| {
+                                Instant::now() + self.me_route_no_writer_wait
+                            });
+                            if !async_recovery_triggered {
+                                let triggered =
+                                    self.trigger_async_recovery_for_target_dc(target_dc).await;
+                                if !triggered {
+                                    self.trigger_async_recovery_global().await;
+                                }
+                                async_recovery_triggered = true;
+                            }
+                            if self.wait_for_writer_until(deadline).await {
+                                continue;
+                            }
+                            self.stats.increment_me_no_writer_failfast_total();
+                            return Err(ProxyError::Proxy(
+                                "No ME writer available in failfast window".into(),
+                            ));
+                        }
+                        MeRouteNoWriterMode::InlineRecoveryLegacy => {
+                            self.stats.increment_me_inline_recovery_total();
+                            for _ in 0..self.me_route_inline_recovery_attempts.max(1) {
+                                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(),
+                                    };
+                                    for (_dc, addrs) in &map {
+                                        for (ip, port) in addrs {
+                                            let addr = SocketAddr::new(*ip, *port);
+                                            let _ = self.connect_one(addr, self.rng.as_ref()).await;
+                                        }
+                                    }
+                                }
+                                if !self.writers.read().await.is_empty() {
                                     break;
                                 }
                             }
-                        }
-                    }
-                    if !self.writers.read().await.is_empty() {
-                        continue;
-                    }
-                    if tokio::time::timeout(Duration::from_secs(3), waiter).await.is_err() {
-                        if !self.writers.read().await.is_empty() {
+                            if !self.writers.read().await.is_empty() {
+                                continue;
+                            }
+                            let waiter = self.writer_available.notified();
+                            if tokio::time::timeout(self.me_route_inline_recovery_wait, waiter)
+                                .await
+                                .is_err()
+                            {
+                                if !self.writers.read().await.is_empty() {
+                                    continue;
+                                }
+                                self.stats.increment_me_no_writer_failfast_total();
+                                return Err(ProxyError::Proxy(
+                                    "All ME connections dead (legacy wait timeout)".into(),
+                                ));
+                            }
+                            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;
                         }
-                        return Err(ProxyError::Proxy("All ME connections dead (waited 3s)".into()));
                     }
-                    continue;
                 }
                 ws.clone()
             };
@@ -115,45 +168,81 @@ impl MePool {
                     .await;
             }
             if candidate_indices.is_empty() {
-                // Emergency connect-on-demand
-                if emergency_attempts >= 3 {
-                    return Err(ProxyError::Proxy("No ME writers available for target DC".into()));
-                }
-                emergency_attempts += 1;
-                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,
-                    };
-                    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;
+                match no_writer_mode {
+                    MeRouteNoWriterMode::AsyncRecoveryFailfast => {
+                        let deadline = *no_writer_deadline.get_or_insert_with(|| {
+                            Instant::now() + self.me_route_no_writer_wait
+                        });
+                        if !async_recovery_triggered {
+                            let triggered = self.trigger_async_recovery_for_target_dc(target_dc).await;
+                            if !triggered {
+                                self.trigger_async_recovery_global().await;
+                            }
+                            async_recovery_triggered = true;
+                        }
+                        if self.wait_for_candidate_until(target_dc, deadline).await {
+                            continue;
+                        }
+                        self.stats.increment_me_no_writer_failfast_total();
+                        return Err(ProxyError::Proxy(
+                            "No ME writers available for target DC in failfast window".into(),
+                        ));
+                    }
+                    MeRouteNoWriterMode::InlineRecoveryLegacy => {
+                        self.stats.increment_me_inline_recovery_total();
+                        if emergency_attempts >= self.me_route_inline_recovery_attempts.max(1) {
+                            self.stats.increment_me_no_writer_failfast_total();
+                            return Err(ProxyError::Proxy("No ME writers available for target DC".into()));
+                        }
+                        emergency_attempts += 1;
+                        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,
+                            };
+                            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)).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;
+                            return Err(ProxyError::Proxy("No ME writers available for target DC".into()));
                         }
                     }
-                }
-                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;
@@ -275,6 +364,151 @@ impl MePool {
         }
     }
 
+    async fn wait_for_writer_until(&self, deadline: Instant) -> bool {
+        let waiter = self.writer_available.notified();
+        if !self.writers.read().await.is_empty() {
+            return true;
+        }
+        let now = Instant::now();
+        if now >= deadline {
+            return !self.writers.read().await.is_empty();
+        }
+        let timeout = deadline.saturating_duration_since(now);
+        if tokio::time::timeout(timeout, waiter).await.is_ok() {
+            return true;
+        }
+        !self.writers.read().await.is_empty()
+    }
+
+    async fn wait_for_candidate_until(&self, target_dc: i16, deadline: Instant) -> bool {
+        loop {
+            if self.has_candidate_for_target_dc(target_dc).await {
+                return true;
+            }
+
+            let now = Instant::now();
+            if now >= deadline {
+                return self.has_candidate_for_target_dc(target_dc).await;
+            }
+
+            let remaining = deadline.saturating_duration_since(now);
+            let sleep_for = remaining.min(Duration::from_millis(25));
+            let waiter = self.writer_available.notified();
+            tokio::select! {
+                _ = waiter => {}
+                _ = tokio::time::sleep(sleep_for) => {}
+            }
+        }
+    }
+
+    async fn has_candidate_for_target_dc(&self, target_dc: i16) -> bool {
+        let writers_snapshot = {
+            let ws = self.writers.read().await;
+            if ws.is_empty() {
+                return false;
+            }
+            ws.clone()
+        };
+        let mut 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;
+        }
+        !candidate_indices.is_empty()
+    }
+
+    async fn trigger_async_recovery_for_target_dc(self: &Arc<Self>, target_dc: i16) -> bool {
+        let endpoints = self.endpoint_candidates_for_target_dc(target_dc).await;
+        if endpoints.is_empty() {
+            return false;
+        }
+        self.stats.increment_me_async_recovery_trigger_total();
+        for addr in endpoints.into_iter().take(8) {
+            self.trigger_immediate_refill(addr);
+        }
+        true
+    }
+
+    async fn trigger_async_recovery_global(self: &Arc<Self>) {
+        self.stats.increment_me_async_recovery_trigger_total();
+        let mut seen = HashSet::<SocketAddr>::new();
+        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(),
+            };
+            for addrs in map.values() {
+                for (ip, port) in addrs {
+                    let addr = SocketAddr::new(*ip, *port);
+                    if seen.insert(addr) {
+                        self.trigger_immediate_refill(addr);
+                    }
+                    if seen.len() >= 8 {
+                        return;
+                    }
+                }
+            }
+        }
+    }
+
+    async fn endpoint_candidates_for_target_dc(&self, target_dc: i16) -> Vec<SocketAddr> {
+        let key = target_dc as i32;
+        let mut preferred = Vec::<SocketAddr>::new();
+        let mut seen = HashSet::<SocketAddr>::new();
+
+        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 def = self.default_dc.load(Ordering::Relaxed);
+            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);
+                        if seen.insert(addr) {
+                            preferred.push(addr);
+                        }
+                    }
+                }
+            }
+            if !preferred.is_empty() && !self.decision.effective_multipath {
+                break;
+            }
+        }
+
+        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);
@@ -292,6 +526,37 @@ impl MePool {
         Ok(())
     }
 
+    pub async fn send_close_conn(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);
+            p.extend_from_slice(&RPC_CLOSE_CONN_U32.to_le_bytes());
+            p.extend_from_slice(&conn_id.to_le_bytes());
+            match w.tx.try_send(WriterCommand::DataAndFlush(p)) {
+                Ok(()) => {}
+                Err(TrySendError::Full(cmd)) => {
+                    let _ = tokio::time::timeout(Duration::from_millis(50), w.tx.send(cmd)).await;
+                }
+                Err(TrySendError::Closed(_)) => {
+                    debug!(conn_id, "ME close_conn skipped: writer channel closed");
+                }
+            }
+        } else {
+            debug!(conn_id, "ME close_conn skipped (writer missing)");
+        }
+
+        self.registry.unregister(conn_id).await;
+        Ok(())
+    }
+
+    pub async fn shutdown_send_close_conn_all(self: &Arc<Self>) -> usize {
+        let conn_ids = self.registry.active_conn_ids().await;
+        let total = conn_ids.len();
+        for conn_id in conn_ids {
+            let _ = self.send_close_conn(conn_id).await;
+        }
+        total
+    }
+
     pub fn connection_count(&self) -> usize {
         self.conn_count.load(Ordering::Relaxed)
     }

src/transport/upstream.rs

@@ -225,6 +225,7 @@ 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 +236,7 @@ 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 +250,7 @@ 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,
@@ -593,11 +596,27 @@ 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 +726,7 @@ 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 +755,6 @@ 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 +781,6 @@ 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 +859,6 @@ 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 +1182,14 @@ 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 +1361,12 @@ 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;