ME Adaptive Floor: merge pull request #299 from telemt/flow-drift

ME Adaptive Floor

Cargo.lock

@@ -2087,7 +2087,7 @@ dependencies = [
 
 [[package]]
 name = "telemt"
-version = "3.0.13"
+version = "3.1.3"
 dependencies = [
  "aes",
  "anyhow",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "telemt"
-version = "3.1.3"
+version = "3.1.5"
 edition = "2024"
 
 [dependencies]

README.md

@@ -215,10 +215,12 @@ hello = "00000000000000000000000000000000"
 
 ```
 ### Advanced
-#### Adtag
-To use channel advertising and usage statistics from Telegram, get Adtag from [@mtproxybot](https://t.me/mtproxybot), add this parameter to section `[General]`
+#### Adtag (per-user)
+To use channel advertising and usage statistics from Telegram, get an Adtag from [@mtproxybot](https://t.me/mtproxybot). Set it per user in `[access.user_ad_tags]` (32 hex chars):
 ```toml
-ad_tag = "00000000000000000000000000000000" # Replace zeros to your adtag from @mtproxybot
+[access.user_ad_tags]
+username1 = "11111111111111111111111111111111"  # Replace with your tag from @mtproxybot
+username2 = "22222222222222222222222222222222"
 ```
 #### Listening and Announce IPs
 To specify listening address and/or address in links, add to section `[[server.listeners]]` of config.toml:

config.full.toml

@@ -1,176 +1,669 @@
-# Telemt full config with default values.
-# Examples are kept in comments after '#'.
+# ==============================================================================
+#
+#   TELEMT — Advanced Rust-based Telegram MTProto Proxy
+#   Full Configuration Reference
+#
+#   This file is both a working config and a complete documentation.
+#   Every parameter is explained. Read it top to bottom before deploying.
+#
+#   Quick Start:
+#     1. Set [server].port to your desired port (443 recommended)
+#     2. Generate a secret: openssl rand -hex 16
+#     3. Put it in [access.users] under a name you choose
+#     4. Set [censorship].tls_domain to a popular unblocked HTTPS site
+#     5. Set your public IP in [general].middle_proxy_nat_ip
+#        and [general.links].public_host
+#     6. Set announce IP in [[server.listeners]]
+#     7. Run Telemt. It prints a tg:// link. Send it to your users.
+#
+#   Modes of Operation:
+#     Direct Mode  (use_middle_proxy = false)
+#       Connects straight to Telegram DCs via TCP. Simple, fast, low overhead.
+#       No ad_tag support. No CDN DC support (203, etc).
+#
+#     Middle-Proxy Mode  (use_middle_proxy = true)
+#       Connects to Telegram Middle-End servers via RPC protocol.
+#       Required for ad_tag monetization and CDN support.
+#       Requires proxy_secret_path and a valid public IP.
+#
+# ==============================================================================
 
-# Top-level legacy field.
-show_link = [] # example: "*" or ["alice", "bob"]
-# default_dc = 2 # example: default DC for unmapped non-standard DCs
+
+# ==============================================================================
+# LEGACY TOP-LEVEL FIELDS
+# ==============================================================================
+
+# Deprecated. Use [general.links].show instead.
+# Accepts "*" for all users, or an array like ["alice", "bob"].
+show_link = ["0"]
+
+# Fallback Datacenter index (1-5) when a client requests an unknown DC ID.
+# DC 2 is Amsterdam (Europe), closest for most CIS users.
+# default_dc = 2
+
+
+# ==============================================================================
+# GENERAL SETTINGS
+# ==============================================================================
 
 [general]
+
+# ------------------------------------------------------------------------------
+# Core Protocol
+# ------------------------------------------------------------------------------
+
+# Coalesce the MTProto handshake and first data payload into a single TCP packet.
+# Significantly reduces connection latency. No reason to disable.
 fast_mode = true
-use_middle_proxy = false
-# ad_tag = "00000000000000000000000000000000" # example
-# proxy_secret_path = "proxy-secret" # example custom path
-# middle_proxy_nat_ip = "203.0.113.10" # example public NAT IP override
+
+# How the proxy connects to Telegram servers.
+# false = Direct TCP to Telegram DCs (simple, low overhead)
+# true  = Middle-End RPC protocol (required for ad_tag and CDN DCs)
+use_middle_proxy = true
+
+# 32-char hex Ad-Tag from @MTProxybot for sponsored channel injection.
+# Only works when use_middle_proxy = true.
+# Obtain yours: message @MTProxybot on Telegram, register your proxy.
+# ad_tag = "00000000000000000000000000000000"
+
+# ------------------------------------------------------------------------------
+# Middle-End Authentication
+# ------------------------------------------------------------------------------
+
+# Path to the Telegram infrastructure AES key file.
+# Auto-downloaded from https://core.telegram.org/getProxySecret on first run.
+# This key authenticates your proxy with Middle-End servers.
+proxy_secret_path = "proxy-secret"
+
+# ------------------------------------------------------------------------------
+# Public IP Configuration (Critical for Middle-Proxy Mode)
+# ------------------------------------------------------------------------------
+
+# Your server's PUBLIC IPv4 address.
+# Middle-End servers need this for the cryptographic Key Derivation Function.
+# If your server has a direct public IP, set it here.
+# If behind NAT (AWS, Docker, etc.), this MUST be your external IP.
+# If omitted, Telemt uses STUN to auto-detect (see middle_proxy_nat_probe).
+# middle_proxy_nat_ip = "203.0.113.10"
+
+# Auto-detect public IP via STUN servers defined in [network].
+# Set to false if you hardcoded middle_proxy_nat_ip above.
+# Set to true if you want automatic detection.
 middle_proxy_nat_probe = true
-# middle_proxy_nat_stun = "stun.l.google.com:19302" # example
-# middle_proxy_nat_stun_servers = [] # example: ["stun1.l.google.com:19302", "stun2.l.google.com:19302"]
+
+# ------------------------------------------------------------------------------
+# Middle-End Connection Pool
+# ------------------------------------------------------------------------------
+
+# Number of persistent multiplexed RPC connections to ME servers.
+# All client traffic is routed through these "fat pipes".
+# 8 handles thousands of concurrent users comfortably.
 middle_proxy_pool_size = 8
+
+# Legacy field. Connections kept initialized but idle as warm standby.
 middle_proxy_warm_standby = 16
+
+# ------------------------------------------------------------------------------
+# Middle-End Keepalive
+# Telegram ME servers aggressively kill idle TCP connections.
+# These settings send periodic RPC_PING frames to keep pipes alive.
+# ------------------------------------------------------------------------------
+
 me_keepalive_enabled = true
+
+# Base interval between pings in seconds.
 me_keepalive_interval_secs = 25
+
+# Random jitter added to interval to prevent all connections pinging simultaneously.
 me_keepalive_jitter_secs = 5
+
+# Randomize ping payload bytes to prevent DPI from fingerprinting ping patterns.
 me_keepalive_payload_random = true
+
+# ------------------------------------------------------------------------------
+# Client-Side Limits
+# ------------------------------------------------------------------------------
+
+# Max buffered ciphertext per client (bytes) when upstream is slow.
+# Acts as backpressure to prevent memory exhaustion. 256KB is safe.
 crypto_pending_buffer = 262144
+
+# Maximum single MTProto frame size from client. 16MB is protocol standard.
 max_client_frame = 16777216
-desync_all_full = false
+
+# ------------------------------------------------------------------------------
+# Crypto Desynchronization Logging
+# Desync errors usually mean DPI/GFW is tampering with connections.
+# ------------------------------------------------------------------------------
+
+# true  = full forensics (trace ID, IP hash, hex dumps) for EVERY desync event
+# false = deduplicated logging, one entry per time window (prevents log spam)
+# Set true if you are actively debugging DPI interference.
+desync_all_full = true
+
+# ------------------------------------------------------------------------------
+# Beobachten — Built-in Honeypot / Active Probe Tracker
+# Tracks IPs that fail handshakes or behave like TLS scanners.
+# Output file can be fed into fail2ban or iptables for auto-blocking.
+# ------------------------------------------------------------------------------
+
 beobachten = true
-beobachten_minutes = 10
+
+# How long (minutes) to remember a suspicious IP before expiring it.
+beobachten_minutes = 30
+
+# How often (seconds) to flush tracker state to disk.
 beobachten_flush_secs = 15
+
+# File path for the tracker output.
 beobachten_file = "cache/beobachten.txt"
+
+# ------------------------------------------------------------------------------
+# Hardswap — Zero-Downtime ME Pool Rotation
+# When Telegram updates ME server IPs, Hardswap creates a completely new pool,
+# waits until it is fully ready, migrates traffic, then kills the old pool.
+# Users experience zero interruption.
+# ------------------------------------------------------------------------------
+
 hardswap = true
+
+# ------------------------------------------------------------------------------
+# ME Pool Warmup Staggering
+# When creating a new pool, connections are opened one by one with delays
+# to avoid a burst of SYN packets that could trigger ISP flood protection.
+# ------------------------------------------------------------------------------
+
 me_warmup_stagger_enabled = true
+
+# Delay between each connection creation (milliseconds).
 me_warmup_step_delay_ms = 500
+
+# Random jitter added to the delay (milliseconds).
 me_warmup_step_jitter_ms = 300
+
+# ------------------------------------------------------------------------------
+# ME Reconnect Backoff
+# If an ME server drops the connection, Telemt retries with this strategy.
+# ------------------------------------------------------------------------------
+
+# Max simultaneous reconnect attempts per DC.
 me_reconnect_max_concurrent_per_dc = 8
+
+# Exponential backoff base (milliseconds).
 me_reconnect_backoff_base_ms = 500
+
+# Backoff ceiling (milliseconds). Will never wait longer than this.
 me_reconnect_backoff_cap_ms = 30000
+
+# Number of instant retries before switching to exponential backoff.
 me_reconnect_fast_retry_count = 12
+
+# ------------------------------------------------------------------------------
+# NAT Mismatch Behavior
+# If STUN-detected IP differs from local interface IP (you are behind NAT).
+# false = abort ME mode (safe default)
+# true  = force ME mode anyway (use if you know your NAT setup is correct)
+# ------------------------------------------------------------------------------
+
 stun_iface_mismatch_ignore = false
-unknown_dc_log_path = "unknown-dc.txt" # to disable: set to null
-log_level = "normal" # debug | verbose | normal | silent
+
+# ------------------------------------------------------------------------------
+# Logging
+# ------------------------------------------------------------------------------
+
+# File to log unknown DC requests (DC IDs outside standard 1-5).
+unknown_dc_log_path = "unknown-dc.txt"
+
+# Verbosity: "debug" | "verbose" | "normal" | "silent"
+log_level = "normal"
+
+# Disable ANSI color codes in log output (useful for file logging).
 disable_colors = false
-fast_mode_min_tls_record = 0
+
+# ------------------------------------------------------------------------------
+# FakeTLS Record Sizing
+# Buffer small MTProto packets into larger TLS records to mimic real HTTPS.
+# Real HTTPS servers send records close to MTU size (~1400 bytes).
+# A stream of tiny TLS records is a strong DPI signal.
+# Set to 0 to disable. Set to 1400 for realistic HTTPS emulation.
+# ------------------------------------------------------------------------------
+
+fast_mode_min_tls_record = 1400
+
+# ------------------------------------------------------------------------------
+# Periodic Updates
+# ------------------------------------------------------------------------------
+
+# How often (seconds) to re-fetch ME server lists and proxy secrets
+# from core.telegram.org. Keeps your proxy in sync with Telegram infrastructure.
 update_every = 300
-me_reinit_every_secs = 900
+
+# How often (seconds) to force a Hardswap even if the ME map is unchanged.
+# Shorter intervals mean shorter-lived TCP flows, harder for DPI to profile.
+me_reinit_every_secs = 600
+
+# ------------------------------------------------------------------------------
+# Hardswap Warmup Tuning
+# Fine-grained control over how the new pool is warmed up before traffic switch.
+# ------------------------------------------------------------------------------
+
 me_hardswap_warmup_delay_min_ms = 1000
 me_hardswap_warmup_delay_max_ms = 2000
 me_hardswap_warmup_extra_passes = 3
 me_hardswap_warmup_pass_backoff_base_ms = 500
+
+# ------------------------------------------------------------------------------
+# Config Update Debouncing
+# Telegram sometimes pushes transient/broken configs. Debouncing requires
+# N consecutive identical fetches before applying a change.
+# ------------------------------------------------------------------------------
+
+# ME server list must be identical for this many fetches before applying.
 me_config_stable_snapshots = 2
+
+# Minimum seconds between config applications.
 me_config_apply_cooldown_secs = 300
+
+# Proxy secret must be identical for this many fetches before applying.
 proxy_secret_stable_snapshots = 2
+
+# ------------------------------------------------------------------------------
+# Proxy Secret Rotation
+# ------------------------------------------------------------------------------
+
+# Apply newly downloaded secrets at runtime without restart.
 proxy_secret_rotate_runtime = true
+
+# Maximum acceptable secret length (bytes). Rejects abnormally large secrets.
 proxy_secret_len_max = 256
+
+# ------------------------------------------------------------------------------
+# Hardswap Drain Settings
+# Controls graceful shutdown of old ME connections during pool rotation.
+# ------------------------------------------------------------------------------
+
+# Seconds to keep old connections alive for in-flight data before force-closing.
 me_pool_drain_ttl_secs = 90
+
+# Minimum ratio of healthy connections in new pool before draining old pool.
+# 0.8 = at least 80% of new pool must be ready.
 me_pool_min_fresh_ratio = 0.8
+
+# Maximum seconds to wait for drain to complete before force-killing.
 me_reinit_drain_timeout_secs = 120
-# Legacy compatibility fields used when update_every is omitted.
-proxy_secret_auto_reload_secs = 3600
-proxy_config_auto_reload_secs = 3600
+
+# ------------------------------------------------------------------------------
+# NTP Clock Check
+# MTProto uses timestamps. Clock drift > 30 seconds breaks handshakes.
+# Telemt checks on startup and warns if out of sync.
+# ------------------------------------------------------------------------------
+
 ntp_check = true
-ntp_servers = ["pool.ntp.org"] # example: ["pool.ntp.org", "time.cloudflare.com"]
+ntp_servers = ["pool.ntp.org"]
+
+# ------------------------------------------------------------------------------
+# Auto-Degradation
+# If ME servers become completely unreachable (ISP blocking),
+# automatically fall back to Direct Mode so users stay connected.
+# ------------------------------------------------------------------------------
+
 auto_degradation_enabled = true
+
+# Number of DC groups that must be unreachable before triggering fallback.
 degradation_min_unavailable_dc_groups = 2
 
+
+# ==============================================================================
+# ALLOWED CLIENT PROTOCOLS
+# Only enable what you need. In censored regions, TLS-only is safest.
+# ==============================================================================
+
 [general.modes]
+
+# Classic MTProto. Unobfuscated length prefixes. Trivially detected by DPI.
+# No reason to enable unless you have ancient clients.
 classic = false
+
+# Obfuscated MTProto with randomized padding. Better than classic, but
+# still detectable by statistical analysis of packet sizes.
 secure = false
+
+# FakeTLS (ee-secrets). Wraps MTProto in TLS 1.3 framing.
+# To DPI, it looks like a normal HTTPS connection.
+# This should be the ONLY enabled mode in censored environments.
 tls = true
 
+
+# ==============================================================================
+# STARTUP LINK GENERATION
+# Controls what tg:// invite links are printed to console on startup.
+# ==============================================================================
+
 [general.links]
-show ="*" # example: "*" or ["alice", "bob"]
-# public_host = "proxy.example.com" # example explicit host/IP for tg:// links
-# public_port = 443 # example explicit port for tg:// links
+
+# Which users to generate links for.
+# "*" = all users, or an array like ["alice", "bob"].
+show = "*"
+
+# IP or domain to embed in the tg:// link.
+# If omitted, Telemt uses STUN to auto-detect.
+# Set this to your server's public IP or domain for reliable links.
+# public_host = "proxy.example.com"
+
+# Port to embed in the tg:// link.
+# If omitted, uses [server].port.
+# public_port = 443
+
+
+# ==============================================================================
+# NETWORK & IP RESOLUTION
+# ==============================================================================
 
 [network]
+
+# Enable IPv4 for outbound connections to Telegram.
 ipv4 = true
-ipv6 = false # set true to enable IPv6
-prefer = 4 # 4 or 6
+
+# Enable IPv6 for outbound connections to Telegram.
+ipv6 = false
+
+# Prefer IPv4 (4) or IPv6 (6) when both are available.
+prefer = 4
+
+# Experimental: use both IPv4 and IPv6 ME servers simultaneously.
+# May improve reliability but doubles connection count.
 multipath = false
+
+# STUN servers for external IP discovery.
+# Used for Middle-Proxy KDF (if nat_probe=true) and link generation.
 stun_servers = [
-  "stun.l.google.com:5349",
-  "stun1.l.google.com:3478",
-  "stun.gmx.net:3478",
-  "stun.l.google.com:19302",
-  "stun.1und1.de:3478",
-  "stun1.l.google.com:19302",
-  "stun2.l.google.com:19302",
-  "stun3.l.google.com:19302",
-  "stun4.l.google.com:19302",
-  "stun.services.mozilla.com:3478",
-  "stun.stunprotocol.org:3478",
-  "stun.nextcloud.com:3478",
-  "stun.voip.eutelia.it:3478",
+    "stun.l.google.com:5349",
+    "stun1.l.google.com:3478",
+    "stun.gmx.net:3478",
+    "stun.l.google.com:19302"
 ]
+
+# If UDP STUN is blocked, attempt TCP-based STUN as fallback.
 stun_tcp_fallback = true
-http_ip_detect_urls = ["https://ifconfig.me/ip", "https://api.ipify.org"]
+
+# If all STUN fails, use HTTP APIs to discover public IP.
+http_ip_detect_urls = [
+    "https://ifconfig.me/ip",
+    "https://api.ipify.org"
+]
+
+# Cache discovered public IP to this file to survive restarts.
 cache_public_ip_path = "cache/public_ip.txt"
 
+
+# ==============================================================================
+# SERVER BINDING & METRICS
+# ==============================================================================
+
 [server]
+
+# TCP port to listen on.
+# 443 is recommended (looks like normal HTTPS traffic).
 port = 443
+
+# IPv4 bind address. "0.0.0.0" = all interfaces.
 listen_addr_ipv4 = "0.0.0.0"
+
+# IPv6 bind address. "::" = all interfaces.
 listen_addr_ipv6 = "::"
-# listen_unix_sock = "/var/run/telemt.sock" # example
-# listen_unix_sock_perm = "0660" # example unix socket mode
-# listen_tcp = true # example explicit override (auto-detected when omitted)
+
+# Unix socket listener (for reverse proxy setups with Nginx/HAProxy).
+# listen_unix_sock = "/var/run/telemt.sock"
+# listen_unix_sock_perm = "0660"
+
+# Enable PROXY protocol header parsing.
+# Set true ONLY if Telemt is behind HAProxy/Nginx that injects PROXY headers.
+# If enabled without a proxy in front, clients will fail to connect.
 proxy_protocol = false
-# metrics_port = 9090 # example
-metrics_whitelist = ["127.0.0.1/32", "::1/128"]
-# Example explicit listeners (default: omitted, auto-generated from listen_addr_*):
+
+# Prometheus metrics HTTP endpoint port.
+# Uncomment to enable. Access at http://your-server:9090/metrics
+# metrics_port = 9090
+
+# IP ranges allowed to access the metrics endpoint.
+metrics_whitelist = [
+    "127.0.0.1/32",
+    "::1/128"
+]
+
+# ------------------------------------------------------------------------------
+# Listener Overrides
+# Define explicit listeners with specific bind IPs and announce IPs.
+# The announce IP is what gets embedded in tg:// links and sent to ME servers.
+# You MUST set announce to your server's public IP for ME mode to work.
+# ------------------------------------------------------------------------------
+
 # [[server.listeners]]
 # ip = "0.0.0.0"
-# announce = "proxy-v4.example.com"
-# # announce_ip = "203.0.113.10" # deprecated alias
-# proxy_protocol = false
-# reuse_allow = false
-#
-# [[server.listeners]]
-# ip = "::"
-# announce = "proxy-v6.example.com"
-# proxy_protocol = false
+# announce = "203.0.113.10"
 # reuse_allow = false
 
+
+# ==============================================================================
+# TIMEOUTS (seconds unless noted)
+# ==============================================================================
+
 [timeouts]
+
+# Maximum time for client to complete FakeTLS + MTProto handshake.
 client_handshake = 15
+
+# Maximum time to establish TCP connection to upstream Telegram DC.
 tg_connect = 10
+
+# TCP keepalive interval for client connections.
 client_keepalive = 60
+
+# Maximum client inactivity before dropping the connection.
 client_ack = 300
+
+# Instant retry count for a single ME endpoint before giving up on it.
 me_one_retry = 3
+
+# Timeout (milliseconds) for a single ME endpoint connection attempt.
 me_one_timeout_ms = 1500
 
+
+# ==============================================================================
+# ANTI-CENSORSHIP / FAKETLS / MASKING
+# This is where Telemt becomes invisible to Deep Packet Inspection.
+# ==============================================================================
+
 [censorship]
-tls_domain = "petrovich.ru"
-# tls_domains = ["example.com", "cdn.example.net"] # Additional domains for EE links
+
+# ------------------------------------------------------------------------------
+# TLS Domain Fronting
+# The SNI (Server Name Indication) your proxy presents to connecting clients.
+# Must be a popular, unblocked HTTPS website in your target country.
+# DPI sees traffic to this domain. Choose carefully.
+# Good choices: major CDNs, banks, government sites, search engines.
+# Bad choices: obscure sites, already-blocked domains.
+# ------------------------------------------------------------------------------
+
+tls_domain = "www.google.com"
+
+# ------------------------------------------------------------------------------
+# Active Probe Masking
+# When someone connects but fails the MTProto handshake (wrong secret),
+# they might be an ISP active prober testing if this is a proxy.
+#
+# mask = false: drop the connection (prober knows something is here)
+# mask = true:  transparently proxy them to mask_host (prober sees a real website)
+#
+# With mask enabled, your server is indistinguishable from a real web server
+# to anyone who doesn't have the correct secret.
+# ------------------------------------------------------------------------------
+
 mask = true
-# mask_host = "www.google.com" # example, defaults to tls_domain when both mask_host/mask_unix_sock are unset
-# mask_unix_sock = "/var/run/nginx.sock" # example, mutually exclusive with mask_host
+
+# The real web server to forward failed handshakes to.
+# If omitted, defaults to tls_domain.
+# mask_host = "www.google.com"
+
+# Port on the mask host to connect to.
 mask_port = 443
-# mask_proxy_protocol = 0 # Send PROXY protocol header to mask_host: 0 = off, 1 = v1 (text), 2 = v2 (binary)
-fake_cert_len = 2048 # if tls_emulation=false and default value is used, loader may randomize this value at runtime
+
+# Inject PROXY protocol header when forwarding to mask host.
+# 0 = disabled, 1 = v1, 2 = v2. Leave disabled unless mask_host expects it.
+# mask_proxy_protocol = 0
+
+# ------------------------------------------------------------------------------
+# TLS Certificate Emulation
+# ------------------------------------------------------------------------------
+
+# Size (bytes) of the locally generated fake TLS certificate.
+# Only used when tls_emulation is disabled.
+fake_cert_len = 2048
+
+# KILLER FEATURE: Real-Time TLS Emulation.
+# Telemt connects to tls_domain, fetches its actual TLS 1.3 certificate chain,
+# and exactly replicates the byte sizes of ServerHello and Certificate records.
+# Defeats DPI that uses TLS record length heuristics to detect proxies.
+# Strongly recommended in censored environments.
 tls_emulation = true
+
+# Directory to cache fetched TLS certificates.
 tls_front_dir = "tlsfront"
-server_hello_delay_min_ms = 0
-server_hello_delay_max_ms = 0
-tls_new_session_tickets = 0
-tls_full_cert_ttl_secs = 90
+
+# ------------------------------------------------------------------------------
+# ServerHello Timing
+# Real web servers take 30-150ms to respond to ClientHello due to network
+# latency and crypto processing. A proxy responding in <1ms is suspicious.
+# These settings add realistic delay to mimic genuine server behavior.
+# ------------------------------------------------------------------------------
+
+# Minimum delay before sending ServerHello (milliseconds).
+server_hello_delay_min_ms = 50
+
+# Maximum delay before sending ServerHello (milliseconds).
+server_hello_delay_max_ms = 150
+
+# ------------------------------------------------------------------------------
+# TLS Session Tickets
+# Real TLS 1.3 servers send 1-2 NewSessionTicket messages after handshake.
+# A server that sends zero tickets is anomalous and may trigger DPI flags.
+# Set this to match your tls_domain's behavior (usually 2).
+# ------------------------------------------------------------------------------
+
+# tls_new_session_tickets = 0
+
+# ------------------------------------------------------------------------------
+# Full Certificate Frequency
+# When tls_emulation is enabled, this controls how often (per client IP)
+# to send the complete emulated certificate chain.
+#
+# > 0: Subsequent connections within TTL seconds get a smaller cached version.
+#       Saves bandwidth but creates a detectable size difference between
+#       first and repeat connections.
+#
+# = 0: Every connection gets the full certificate. More bandwidth but
+#       perfectly consistent behavior, no anomalies for DPI to detect.
+# ------------------------------------------------------------------------------
+
+tls_full_cert_ttl_secs = 0
+
+# ------------------------------------------------------------------------------
+# ALPN Enforcement
+# Ensure ServerHello responds with the exact ALPN protocol the client requested.
+# Mismatched ALPN (e.g., client asks h2, server says http/1.1) is a DPI red flag.
+# ------------------------------------------------------------------------------
+
 alpn_enforce = true
 
+
+# ==============================================================================
+# ACCESS CONTROL & USERS
+# ==============================================================================
+
 [access]
+
+# ------------------------------------------------------------------------------
+# Replay Attack Protection
+# DPI can record a legitimate user's handshake and replay it later to probe
+# whether the server is a proxy. Telemt remembers recent handshake nonces
+# and rejects duplicates.
+# ------------------------------------------------------------------------------
+
+# Number of nonce slots in the replay detection buffer.
 replay_check_len = 65536
+
+# How long (seconds) to remember nonces before expiring them.
 replay_window_secs = 1800
+
+# Allow clients with incorrect system clocks to connect.
+# false = reject clients with significant time skew (more secure)
+# true  = accept anyone regardless of clock (more permissive)
 ignore_time_skew = false
 
+# ------------------------------------------------------------------------------
+# User Secrets
+# Each user needs a unique 32-character hex string as their secret.
+# Generate with: openssl rand -hex 16
+#
+# This secret is embedded in the tg:// link. Anyone with it can connect.
+# Format: username = "hex_secret"
+# ------------------------------------------------------------------------------
+
 [access.users]
-# format: "username" = "32_hex_chars_secret"
-hello = "00000000000000000000000000000000"
-# alice = "11111111111111111111111111111111" # example
+# alice = "0123456789abcdef0123456789abcdef"
+# bob = "fedcba9876543210fedcba9876543210"
+
+# ------------------------------------------------------------------------------
+# Per-User Connection Limits
+# Limits concurrent TCP connections per user to prevent secret sharing.
+# Uncomment and set for each user as needed.
+# ------------------------------------------------------------------------------
 
 [access.user_max_tcp_conns]
-# alice = 100 # example
+# alice = 100
+# bob = 50
+
+# ------------------------------------------------------------------------------
+# Per-User Expiration Dates
+# Automatically revoke access after the specified date (ISO 8601 format).
+# ------------------------------------------------------------------------------
 
 [access.user_expirations]
-# alice = "2078-01-01T00:00:00Z" # example
+# alice = "2025-12-31T23:59:59Z"
+# bob = "2026-06-15T00:00:00Z"
+
+# ------------------------------------------------------------------------------
+# Per-User Data Quotas
+# Maximum total bytes transferred per user. Connection refused after limit.
+# ------------------------------------------------------------------------------
 
 [access.user_data_quota]
-# hello = 10737418240 # example bytes
-# alice = 10737418240 # example bytes
+# alice = 107374182400
+# bob = 53687091200
+
+# ------------------------------------------------------------------------------
+# Per-User Unique IP Limits
+# Maximum number of different IP addresses that can use this secret
+# at the same time. Highly effective against secret leaking/sharing.
+# Set to 1 for single-device, 2-3 for phone+desktop, etc.
+# ------------------------------------------------------------------------------
 
 [access.user_max_unique_ips]
-# hello = 10 # example
-# alice = 100 # example
+# alice = 3
+# bob = 2
+
+
+# ==============================================================================
+# UPSTREAM ROUTING
+# Controls how Telemt connects to Telegram servers (or ME servers).
+# If omitted entirely, uses the OS default route.
+# ==============================================================================
+
+# ------------------------------------------------------------------------------
+# Direct upstream: use the server's own network interface.
+# You can optionally bind to a specific interface or local IP.
+# ------------------------------------------------------------------------------
 
-# Default behavior if [[upstreams]] is omitted: loader injects one direct upstream.
-# Example explicit upstreams:
 # [[upstreams]]
 # type = "direct"
 # interface = "eth0"
@@ -178,28 +671,27 @@ hello = "00000000000000000000000000000000"
 # weight = 1
 # enabled = true
 # scopes = "*"
-#
-# [[upstreams]]
-# type = "socks4"
-# address = "198.51.100.20:1080"
-# interface = "eth0"
-# user_id = "telemt"
-# weight = 1
-# enabled = true
-# scopes = "*"
-#
+
+# ------------------------------------------------------------------------------
+# SOCKS5 upstream: route Telegram traffic through a SOCKS5 proxy.
+# Useful if your server's IP is blocked from reaching Telegram DCs.
+# ------------------------------------------------------------------------------
+
 # [[upstreams]]
 # type = "socks5"
 # address = "198.51.100.30:1080"
-# interface = "eth0"
 # username = "proxy-user"
 # password = "proxy-pass"
 # weight = 1
 # enabled = true
-# scopes = "*"
 
-# === DC Address Overrides ===
+
+# ==============================================================================
+# DATACENTER OVERRIDES
+# Force specific DC IDs to route to specific IP:Port combinations.
+# DC 203 (CDN) is auto-injected by Telemt if not specified here.
+# ==============================================================================
+
 # [dc_overrides]
-# "201" = "149.154.175.50:443" # example
-# "202" = ["149.154.167.51:443", "149.154.175.100:443"] # example
-# "203" = "91.105.192.100:443" # loader auto-adds this one when omitted
+# "201" = "149.154.175.50:443"
+# "202" = ["149.154.167.51:443", "149.154.175.100:443"]

config.toml

@@ -5,7 +5,9 @@
 # === General Settings ===
 [general]
 use_middle_proxy = false
+# Global ad_tag fallback when user has no per-user tag in [access.user_ad_tags]
 # ad_tag = "00000000000000000000000000000000"
+# Per-user ad_tag in [access.user_ad_tags] (32 hex from @MTProxybot)
 
 # === Log Level ===
 # Log level: debug | verbose | normal | silent

docs/FAQ.ru.md

@@ -0,0 +1,64 @@
+## Как настроить канал "спонсор прокси"
+
+1. Зайти в бота @MTProxybot.
+2. Ввести команду `/newproxy`
+3. Отправить IP и порт сервера. Например: 1.2.3.4:443
+4. Открыть конфиг `nano /etc/telemt.toml`.
+5. Скопировать и отправить боту секрет пользователя из раздела [access.users].
+6. Скопировать полученный tag у бота. Например 1234567890abcdef1234567890abcdef.
+7. Раскомментировать параметр ad_tag и вписать tag, полученный у бота.
+8. Раскомментировать/добавить параметр use_middle_proxy = true.
+
+Пример конфига:
+```toml
+[general]
+ad_tag = "1234567890abcdef1234567890abcdef"
+use_middle_proxy = true
+```
+9.  Сохранить конфиг. Ctrl+S -> Ctrl+X.
+10. Перезапустить telemt `systemctl restart telemt`.
+11. В боте отправить команду /myproxies и выбрать добавленный сервер.
+12. Нажать кнопку "Set promotion".
+13. Отправить **публичную ссылку** на канал. Приватный канал добавить нельзя!
+14. Подождать примерно 1 час, пока информация обновится на серверах Telegram.
+> [!WARNING]
+> У вас не будет отображаться "спонсор прокси" если вы уже подписаны на канал.
+
+## Сколько человек может пользоваться 1 ссылкой
+
+По умолчанию 1 ссылкой может пользоваться сколько угодно человек.  
+Вы можете ограничить число IP, использующих прокси.
+```toml
+[access.user_max_unique_ips]
+hello = 1
+```
+Этот параметр ограничивает, сколько уникальных IP может использовать 1 ссылку одновременно. Если один пользователь отключится, второй сможет подключиться. Также с одного IP может сидеть несколько пользователей.
+
+## Как сделать несколько разных ссылок
+
+1. Сгенерируйте нужное число секретов `openssl rand -hex 16`
+2. Открыть конфиг `nano /etc/telemt.toml`
+3. Добавить новых пользователей.
+```toml
+[access.users]
+user1 = "00000000000000000000000000000001"
+user2 = "00000000000000000000000000000002"
+user3 = "00000000000000000000000000000003"
+```
+4. Сохранить конфиг. Ctrl+S -> Ctrl+X. Перезапускать telemt не нужно.
+5. Получить ссылки через `journalctl -u telemt -n -g "links" --no-pager -o cat | tac`
+
+## Как посмотреть метрики
+
+1. Открыть конфиг `nano /etc/telemt.toml`
+2. Добавить следующие параметры
+```toml
+[server]
+metrics_port = 9090
+metrics_whitelist = ["127.0.0.1/32", "::1/128", "0.0.0.0/0"]
+```
+3. Сохранить конфиг. Ctrl+S -> Ctrl+X.
+4. Метрики доступны по адресу SERVER_IP:9090/metrics. 
+> [!WARNING]
+> "0.0.0.0/0" в metrics_whitelist открывает доступ с любого IP. Замените на свой ip. Например "1.2.3.4"
+

docs/MIDDLE-END-KDF.de.md

@@ -0,0 +1,40 @@
+# Middle-End Proxy
+
+## KDF-Adressierung — Implementierungs-FAQ
+
+### Benötigt die C-Referenzimplementierung sowohl externe IP-Adresse als auch Port für die KDF?
+
+Ja.
+
+In der C-Referenzimplementierung werden **sowohl IP-Adresse als auch Port in die KDF einbezogen** — auf beiden Seiten der Verbindung.
+
+In `aes_create_keys()` enthält der KDF-Input:
+
+- `server_ip + client_port`
+- `client_ip + server_port`
+- sowie Secret / Nonces
+
+Für IPv6:
+
+- IPv4-Felder werden auf 0 gesetzt
+- IPv6-Adressen werden ergänzt
+
+Die **Ports bleiben weiterhin Bestandteil der KDF**.
+
+> Wenn sich externe IP oder Port (z. B. durch NAT, SOCKS oder Proxy) von den erwarteten Werten unterscheiden, entstehen unterschiedliche Schlüssel — der Handshake schlägt fehl.
+
+---
+
+### Kann der Port aus der KDF ausgeschlossen werden (z. B. durch Port = 0)?
+
+**Nein!**
+
+Die C-Referenzimplementierung enthält **keine Möglichkeit, den Port zu ignorieren**:
+- `client_port` und `server_port` sind fester Bestandteil der KDF
+- Es werden immer reale Socket-Ports übergeben:
+  - `c->our_port`
+  - `c->remote_port`
+
+Falls ein Port den Wert `0` hat, wird er dennoch als `0` in die KDF übernommen.
+
+Eine „Port-Ignore“-Logik existiert nicht.

docs/MIDDLE-END-KDF.en.md

@@ -0,0 +1,41 @@
+# Middle-End Proxy
+
+## KDF Addressing — Implementation FAQ
+
+### Does the C-implementation require both external IP address and port for the KDF?
+
+**Yes!**
+
+In the C reference implementation, **both IP address and port are included in the KDF input** from both sides of the connection.
+
+Inside `aes_create_keys()`, the KDF input explicitly contains:
+
+- `server_ip + client_port`
+- `client_ip + server_port`
+- followed by shared secret / nonces
+
+For IPv6:
+
+- IPv4 fields are zeroed
+- IPv6 addresses are inserted
+
+However, **client_port and server_port remain part of the KDF regardless of IP version**.
+
+> If externally observed IP or port (e.g. due to NAT, SOCKS, or proxy traversal) differs from what the peer expects, the derived keys will not match and the handshake will fail.
+
+---
+
+### Can port be excluded from KDF (e.g. by using port = 0)?
+
+**No!**
+
+The C-implementation provides **no mechanism to ignore the port**:
+
+- `client_port` and `server_port` are explicitly included in the KDF input
+- Real socket ports are always passed:
+  - `c->our_port`
+  - `c->remote_port`
+
+If a port is `0`, it is still incorporated into the KDF as `0`.
+
+There is **no conditional logic to exclude ports**

docs/MIDDLE-END-KDF.ru.md

@@ -0,0 +1,41 @@
+# Middle-End Proxy
+
+## KDF Addressing — FAQ по реализации
+
+### Требует ли C-референсная реализация KDF внешний IP и порт?
+
+**Да**
+
+В C-референсе **в KDF участвуют и IP-адрес, и порт** — с обеих сторон соединения.
+
+В `aes_create_keys()` в строку KDF входят:
+
+- `server_ip + client_port`
+- `client_ip + server_port`
+- далее secret / nonces
+
+Для IPv6:
+
+- IPv4-поля заполняются нулями
+- добавляются IPv6-адреса
+
+Однако **порты client_port и server_port всё равно участвуют в KDF**.
+
+> Если внешний IP или порт (например, из-за NAT, SOCKS или прокси) не совпадает с ожидаемым другой стороной — ключи расходятся и handshake ломается.
+
+---
+
+### Можно ли исключить порт из KDF (например, установив порт = 0)?
+
+**Нет.**
+
+В C-референсе **нет механики отключения порта**.
+
+- `client_port` и `server_port` явно включены в KDF
+- Передаются реальные порты сокета:
+  - `c->our_port`
+  - `c->remote_port`
+
+Если порт равен `0`, он всё равно попадёт в KDF как `0`.
+
+Отдельной логики «игнорировать порт» не предусмотрено.

docs/QUICK_START_GUIDE.en.md

@@ -0,0 +1,152 @@
+# Telemt via Systemd
+
+## Installation
+
+This software is designed for Debian-based OS: in addition to Debian, these are Ubuntu, Mint, Kali, MX and many other Linux
+
+**1. Download**
+```bash
+wget -qO- "https://github.com/telemt/telemt/releases/latest/download/telemt-$(uname -m)-linux-$(ldd --version 2>&1 | grep -iq musl && echo musl || echo gnu).tar.gz" | tar -xz
+```
+**2. Move to the Bin folder**
+```bash
+mv telemt /bin
+```
+**3. Make the file executable**
+```bash
+chmod +x /bin/telemt
+```
+
+## How to use?
+
+**This guide "assumes" that you:**
+- logged in as root or executed `su -` / `sudo su`
+- Already have the "telemt" executable file in the /bin folder. Read the **[Installation](#Installation)** section.
+
+---
+
+**0. Check port and generate secrets**
+
+The port you have selected for use should be MISSING from the list, when:
+```bash
+netstat -lnp
+```
+
+Generate 16 bytes/32 characters HEX with OpenSSL or another way:
+```bash
+openssl rand -hex 16
+```
+OR
+```bash
+xxd -l 16 -p /dev/urandom
+```
+OR
+```bash
+python3 -c 'import os; print(os.urandom(16).hex())'
+```
+Save the obtained result somewhere. You will need it later!
+
+---
+
+**1. Place your config to /etc/telemt.toml**
+
+Open nano
+```bash
+nano /etc/telemt.toml
+```
+paste your config
+
+```toml
+# === General Settings ===
+[general]
+# ad_tag = "00000000000000000000000000000000"
+
+[general.modes]
+classic = false
+secure = false
+tls = true
+
+# === Anti-Censorship & Masking ===
+[censorship]
+tls_domain = "petrovich.ru"
+
+[access.users]
+# format: "username" = "32_hex_chars_secret"
+hello = "00000000000000000000000000000000"
+```
+then Ctrl+S -> Ctrl+X to save
+
+> [!WARNING]
+> Replace the value of the hello parameter with the value you obtained in step 0. 
+> Replace the value of the tls_domain parameter with another website.
+
+---
+
+**2. Create service on /etc/systemd/system/telemt.service**
+
+Open nano
+```bash
+nano /etc/systemd/system/telemt.service
+```
+
+paste this Systemd Module
+```bash
+[Unit]
+Description=Telemt
+After=network.target
+
+[Service]
+Type=simple
+WorkingDirectory=/bin
+ExecStart=/bin/telemt /etc/telemt.toml
+Restart=on-failure
+LimitNOFILE=65536
+
+[Install]
+WantedBy=multi-user.target
+```
+then Ctrl+S -> Ctrl+X to save
+
+
+**3.** To start it, enter the command `systemctl start telemt`
+
+**4.** To get status information, enter `systemctl status telemt`
+
+**5.** For automatic startup at system boot, enter `systemctl enable telemt`
+
+**6.** To get the links, enter `journalctl -u telemt -n -g "links" --no-pager -o cat | tac`
+
+---
+
+# Telemt via Docker Compose
+
+**1. Edit `config.toml` in repo root (at least: port, users secrets, tls_domain)**  
+**2. Start container:**
+```bash
+docker compose up -d --build
+```
+**3. Check logs:**
+```bash
+docker compose logs -f telemt
+```
+**4. Stop:**
+```bash
+docker compose down
+```
+> [!NOTE]
+> - `docker-compose.yml` maps `./config.toml` to `/app/config.toml` (read-only)
+> - By default it publishes `443:443` and runs with dropped capabilities (only `NET_BIND_SERVICE` is added)
+> - If you really need host networking (usually only for some IPv6 setups) uncomment `network_mode: host`
+
+**Run without Compose**
+```bash
+docker build -t telemt:local .
+docker run --name telemt --restart unless-stopped \
+  -p 443:443 \
+  -e RUST_LOG=info \
+  -v "$PWD/config.toml:/app/config.toml:ro" \
+  --read-only \
+  --cap-drop ALL --cap-add NET_BIND_SERVICE \
+  --ulimit nofile=65536:65536 \
+  telemt:local
+```

docs/QUICK_START_GUIDE.ru.md

@@ -0,0 +1,152 @@
+# Telemt через Systemd
+
+## Установка
+
+Это программное обеспечение разработано для ОС на базе Debian: помимо Debian, это Ubuntu, Mint, Kali, MX и многие другие Linux
+
+**1. Скачать**
+```bash
+wget -qO- "https://github.com/telemt/telemt/releases/latest/download/telemt-$(uname -m)-linux-$(ldd --version 2>&1 | grep -iq musl && echo musl || echo gnu).tar.gz" | tar -xz
+```
+**2. Переместить в папку Bin**
+```bash
+mv telemt /bin
+```
+**3. Сделать файл исполняемым**
+```bash
+chmod +x /bin/telemt
+```
+
+## Как правильно использовать?
+
+**Эта инструкция "предполагает", что вы:**
+- Авторизовались как пользователь root или выполнил `su -` / `sudo su`
+- У вас уже есть исполняемый файл "telemt" в папке /bin. Читайте раздел **[Установка](#установка)**
+
+---
+
+**0. Проверьте порт и сгенерируйте секреты**
+
+Порт, который вы выбрали для использования, должен отсутствовать в списке:
+```bash
+netstat -lnp
+```
+
+Сгенерируйте 16 bytes/32 символа в шестнадцатеричном формате с помощью OpenSSL или другим способом:
+```bash
+openssl rand -hex 16
+```
+ИЛИ
+```bash
+xxd -l 16 -p /dev/urandom
+```
+ИЛИ
+```bash
+python3 -c 'import os; print(os.urandom(16).hex())'
+```
+Полученный результат сохраняем где-нибудь. Он понадобиться вам дальше!
+
+---
+
+**1. Поместите свою конфигурацию в файл /etc/telemt.toml**
+
+Открываем nano
+```bash
+nano /etc/telemt.toml
+```
+Вставьте свою конфигурацию
+
+```toml
+# === General Settings ===
+[general]
+# ad_tag = "00000000000000000000000000000000"
+
+[general.modes]
+classic = false
+secure = false
+tls = true
+
+# === Anti-Censorship & Masking ===
+[censorship]
+tls_domain = "petrovich.ru"
+
+[access.users]
+# format: "username" = "32_hex_chars_secret"
+hello = "00000000000000000000000000000000"
+```
+Затем нажмите Ctrl+S -> Ctrl+X, чтобы сохранить
+
+> [!WARNING]
+> Замените значение параметра hello на значение, которое вы получили в пункте 0.  
+> Так же замените значение параметра tls_domain на другой сайт.
+
+---
+
+**2. Создайте службу в /etc/systemd/system/telemt.service**
+
+Открываем nano
+```bash
+nano /etc/systemd/system/telemt.service
+```
+
+Вставьте этот модуль Systemd
+```bash
+[Unit]
+Description=Telemt
+After=network.target
+
+[Service]
+Type=simple
+WorkingDirectory=/bin
+ExecStart=/bin/telemt /etc/telemt.toml
+Restart=on-failure
+LimitNOFILE=65536
+
+[Install]
+WantedBy=multi-user.target
+```
+Затем нажмите Ctrl+S -> Ctrl+X, чтобы сохранить
+
+
+**3.** Для запуска введите команду `systemctl start telemt`
+
+**4.** Для получения информации о статусе введите `systemctl status telemt`
+
+**5.** Для автоматического запуска при запуске системы в введите `systemctl enable telemt`
+
+**6.** Для получения ссылки введите `journalctl -u telemt -n -g "links" --no-pager -o cat | tac`
+
+---
+
+# Telemt через Docker Compose
+
+**1. Отредактируйте `config.toml` в корневом каталоге репозитория (как минимум: порт, пользовательские секреты, tls_domain)**  
+**2. Запустите контейнер:**
+```bash
+docker compose up -d --build
+```
+**3. Проверьте логи:**
+```bash
+docker compose logs -f telemt
+```
+**4. Остановите контейнер:**
+```bash
+docker compose down
+```
+> [!NOTE]
+> - В `docker-compose.yml` файл `./config.toml` монтируется в `/app/config.toml` (доступно только для чтения)  
+> - По умолчанию публикуются порты 443:443, а контейнер запускается со сброшенными привилегиями (добавлена только `NET_BIND_SERVICE`)  
+> - Если вам действительно нужна сеть хоста (обычно это требуется только для некоторых конфигураций IPv6), раскомментируйте `network_mode: host`
+
+**Запуск в Docker Compose**
+```bash
+docker build -t telemt:local .
+docker run --name telemt --restart unless-stopped \
+  -p 443:443 \
+  -e RUST_LOG=info \
+  -v "$PWD/config.toml:/app/config.toml:ro" \
+  --read-only \
+  --cap-drop ALL --cap-add NET_BIND_SERVICE \
+  --ulimit nofile=65536:65536 \
+  telemt:local
+```

docs/XRAY-SINGBOX-ROUTING.ru.md

@@ -0,0 +1,321 @@
+# SNI-маршрутизация в xray-core / sing-box + TLS-fronting
+
+## Термины (в контексте этого кейса)
+
+- **TLS-fronting домен** — домен, который фигурирует в TLS ClientHello как **SNI** (например, `petrovich.ru`): он используется как "маска" на L7 и как ключ маршрутизации в прокси-роутере.
+- **xray-core / sing-box** — локальный или удалённый L7/TLS-роутер (прокси), который:
+  1) принимает входящее TCP/TLS-соединение,
+  2) читает TLS ClientHello,
+  3) извлекает SNI,
+  4) по SNI выбирает outbound/апстрим,
+  5) устанавливает новое TCP-соединение к целевому хосту уже **от себя**.
+- **SNI (Server Name Indication)** — поле в TLS ClientHello, где клиент Telegram сообщает доменное имя для "маскировки"
+- **DNS-resolve на стороне L7-роутера** — если выходной адрес задан доменом (или роутер решил "всё равно идти по SNI"), то DNS резолвится **на стороне xray/sing-box**, а не на стороне Telegram-клиента
+
+---
+
+## Ключевая идея: куда на самом деле идёт соединение решает не то, что вы указали клиенту, а то как L7-роутер трактует SNI
+
+Механика:
+
+1) Telegram-клиенту вы можете указать **IP/домен telemt**,как "сервер".
+2) Между клиентом и telemt стоит xray-core/sing-box, который принимает TCP, читает TLS ClientHello и видит **SNI=petrovich.ru**
+3) Дальше роутер говорит: "Вижу SNI - направить на апстрим/маршрут N"
+4) И устанавливает исходящее соединение не "по тому IP, который пользователь подразумевал", а **по домену из SNI** (или по сопоставлению SNI→outbound), используя для определния его IP собственный DNS-кеш или резолвер
+5) `petrovich.ru` по A-записи указывает **не на IP telemt**, а значит при L7-маршрутизации трафик уйдёт на "оригинальный" сайт за этим доменом, а не в telemt: Telegram-клиент, естественно, не сможет получить ожидаемое поведение, потому что ответить с handshake на той стороне некому
+
+---
+
+## Схема №1 "Как это НЕ работает"
+
+```text
+Telegram Client
+   |
+   |  (указан IP/домен telemt)
+   v
+telemt instance
+````
+
+Ожидание: "я указал telemt -> значит трафик попадёт в telemt" - **нет!**
+
+---
+
+## Схема №2. "Как это реально работает с TLS/L7-роутером и SNI"
+
+```text
+Telegram Client
+   |
+   | 1) TCP/TLS connection: 
+   |    - ClientHello: 
+   |      - SNI=petrovich.ru
+   v
+xray-core / sing-box / любой L7 router
+   |
+   | 2) читает ClientHello -> вытаскивает SNI
+   | 3) выбирает маршрут по SNI
+   | 4) делает DNS для petrovich.ru 
+   | 5) подключается к полученному IP по TLS с этим SNI
+   v
+"Оригинальный" сайт, A-запись которого не на telemt
+   |
+   X  не telemt -> Telegram-клиент не коннектится как ожидалось
+```
+
+---
+
+## Почему указанный в клиенте IP/домен telemt "не спасает"
+
+Потому что в таком режиме xray/sing-box выступает как **точка терминации TCP/TLS**, можно сказать - TLS-инспектор на уровне ClientHello, это означает:
+
+* TCP-сессия от Telegram-клиента заканчивается на xray/sing-box
+* Дальше создаётся **новая** TCP-сессия "от имени" xray/sing-box к апстриму
+* Выбор апстрима делается правилами роутинга, а в TLS-сценариях самый удобный и распространённый ключ — **SNI**
+
+То есть, "куда идти дальше" определяется логикой L7-роутера:
+
+* либо правилами вида `if SNI == petrovich.ru -> outbound X`,
+* либо более "автоматическим" поведением: `подключаться к тому хосту, который указан в SNI`,
+* плюс кэш DNS и собственные резолверы роутера
+
+---
+
+## Что именно извлекается из TLS ClientHello и почему этого достаточно
+
+TLS ClientHello отправляется **в начале** TLS-сессии и, в классическом TLS без ECH, содержит SNI в открытом виде.
+
+Упрощённо:
+
+```text
+ClientHello:
+  - supported_versions
+  - cipher_suites
+  - extensions:
+      - server_name: petrovich.ru   <-- SNI
+      - alpn: h2/http1.1/...
+      - ...
+```
+
+Роутеру не нужно расшифровывать трафик и завершать TLS "как сервер" — часто достаточно просто прочитать первые пакеты и распарсить ClientHello, чтобы получить SNI и принять решение
+
+---
+
+## Типовой алгоритм SNI-роутинга
+
+1. Принять входящий TCP.
+2. Подождать первые байты.
+3. Определить протокол:
+
+   * если видим TLS ClientHello → парсим SNI/ALPN
+4. Применить route rules:
+
+   * match по `server_name` / `domain` / `tls.sni`
+5. Выбрать outbound:
+
+   * direct / proxy / specific upstream / detour
+6. Установить исходящее соединение:
+
+   * либо на фиксированный IP:порт,
+   * либо на домен через DNS-resolve на стороне роутера
+7. Начать проксирование данных между входом и выходом
+
+---
+
+## Почему "A-запись фронтинг-домена не на telemt" ломает кейс
+
+### Ситуация
+
+* В ClientHello: `SNI = petrovich.ru`
+* DNS: `petrovich.ru -> 203.0.113.77`  - "оригинальный" сайт
+* telemt живёт на: `198.51.100.10`
+
+### Что делает роутер
+
+* Видит SNI `petrovich.ru`
+* Либо:
+
+  * (а) напрямую коннектится к `petrovich.ru:443`, резолвя A-запись в `203.0.113.77`,
+  * либо:
+  * (б) выбирает outbound, который указывает на `petrovich.ru` как destination,
+  * либо:
+  * (в) делает sniffing/override destination по SNI
+
+В итоге исходящий коннект идёт на `203.0.113.77:443`, а не на telemt!
+Другой сервер, другой протокол, другая логика, где telemt не участвует
+
+---
+
+## "Где именно происходит подмена destination на SNI"
+
+Это зависит от конфигурации, но типовые варианты:
+
+### Вариант A: outbound задан доменом (и он совпадает с SNI)
+
+Правило по SNI выбирает outbound, у которого destination задан доменом фронтинга, 
+тогда DNS резолвится на стороне роутера и вы уходите на "оригинальный" хост
+
+### Вариант B: destination override / sniffing
+
+Роутер "снифает" SNI и **перезаписывает** destination на домен из SNI (даже если вход изначально был на IP telemt),
+это особенно коварно: пользователь видит "я подключаюсь к IP telemt", но роутер после sniffing решает иначе
+
+### Вариант C: split DNS / кеш / независимый резолвер
+
+Даже если клиент "где-то" резолвит иначе, это не важно: конечный DNS для исходящего коннекта — на стороне xray/sing-box,
+который может иметь:
+
+* свой DoH/DoT,
+* свой кеш,
+* свои правила fake-ip / system resolver,
+* и, как следствие, своя "карта" **домен/SNI -> IP**
+
+---
+
+## Признаки того, что трафик "утёк на оригинал", а не попал в telemt
+
+* На стороне telemt отсутствуют входящие соединения/логи
+* На стороне роутера видно, что destination — домен фронтинга, а IP соответствует публичному сайту
+* TLS-метрики/сертификат на выходе соответствует "оригинальному" сайту в записах трафика
+* Telegram-клиент получает неожиданный тип ответов/ошибку handshaking/timeout в debug-режиме
+
+---
+
+## Best-practice решение для этого кейса: свой домен фронтинга + заглушка на telemt + Let's Encrypt
+
+### Цель
+
+Сделать так, чтобы:
+
+* SNI (фронтинг-домен) **резолвился в IP telemt**,
+* на IP telemt реально был TLS-сервис с валидным сертификатом под этот домен,
+* даже если кто-то "попробует открыть домен как сайт", он увидит нормальную заглушку, а не "пустоту"
+
+### Что это даёт
+
+* xray/sing-box, маршрутизируя по SNI, будет неизбежно приходить на telemt, потому что DNS(SNI-домен) → IP telemt
+* Внешний вид будет правдоподобным: обычный домен с обычным сертификатом
+* Устойчивость: меньше сюрпризов от DNS-кеша/перерезолва/"умных" правил роутера
+
+---
+
+## Рекомендуемая схема (целевое состояние)
+
+```text
+Telegram Client
+   |
+   | TLS ClientHello: SNI = hello.example.com
+   v
+xray-core / sing-box
+   |
+   | Route by SNI -> outbound -> connect to hello.example.com:443
+   | DNS(hello.example.com) = IP telemt
+   v
+telemt instance (IP telemt)
+   |
+   | TLS cert for hello.example.com (Let's Encrypt)
+   | + сайт-заглушка / health endpoint
+   v
+OK
+```
+
+---
+
+## Практический чеклист (минимальный)
+
+1. Купить/иметь домен: `hello.example.com`
+2. В DNS:
+
+   * `A hello.example.com -> <IP telemt>`
+   * (опционально) AAAA, если используете IPv6 и он стабилен
+3. На telemt-хосте:
+
+   * поднять TLS endpoint на 443 с валидным сертификатом LE под `hello.example.com`
+   * отдать "заглушку" (например, статический сайт), чтобы домен выглядел как обычный веб-сервис
+4. В xray/sing-box правилах:
+
+   * маршрутизировать нужный трафик по SNI = `hello.example.com` в "правильный" outbound (к telemt)
+   * избегать конфигураций, где destination override уводит на чужой домен
+5. Важно:
+
+   * если вы используете кеш DNS на роутере — сбросить/обновить его после смены A-записи
+
+---
+
+## Пояснение про сайт-заглушку
+
+Для эмуляции TLS, telemt имеет подсистему TLS-F в `src/tls_front`:
+- её модуль - fetcher, собирает TLS-профили, чтоб максимально поведенчески корректно повторять TLS конкретно указанного сайта
+
+Когда вы указываете сайт, который не отвечает по TLS:
+- fetcher не может собрать TLS-профиль и происходит fallback на `fake_cert_len` - примитивный алгоритм,
+- он забивает служебную информацию TLS рандомными байтами,
+- простые системы DPI не распознают это
+- однако, продвинутые системы, такие как nEdge или Fraud Control в сетях мобильной связи легко заблокируют или замедлят такой трафик
+
+Создав сайт-заглушку с Let's Encrypt сертификатом, вы даёте TLS-F возможность получить данные сертификата и корректно его "повторять" в дальнейшем
+
+---
+
+## Вариант конфиг-подхода: "SNI строго привязываем к telemt - фиксированный IP"
+
+Чтобы полностью исключить зависимость от DNS если вам это нужно, можно сделать outbound, который ходит на **фиксированный IP telemt**, но при этом выставляет SNI/Host как `hello.example.com`.
+
+Идея:
+
+* destination: `IP:443`
+* SNI: `hello.example.com`
+* сертификат на telemt именно под `hello.example.com`
+
+Так вы получаете:
+
+* TLS выглядит корректно, ведь SNI совпадает с сертификатом,
+* а routing никогда не уйдёт на "оригинал", потому что A-запись указывает на telemt и контроллируется вами!
+
+Но в вашем описании проблема как раз в том, что роутер "сам решает по SNI и резолвит домен", поэтому самый универсальный вариант — сделать так, чтобы DNS всегда приводил в telemt
+
+---
+
+## Пример логики правил на псевдоконфиге L7-роутера
+
+```text
+if inbound is TLS and sni == "hello.example.com":
+    route -> outbound "telemt"
+else:
+    route -> outbound "default"
+```
+
+Outbound `telemt`:
+
+* destination: `hello.example.com:443`
+* TLS enabled
+* SNI: `hello.example.com`
+
+---
+
+## Отдельно: что может неожиданно сломать даже "правильный" DNS
+
+* **Кеширование DNS** на xray/sing-box или на системном резолвере, особенно при смене A-записи
+* **Split-horizon DNS**: разные ответы внутри/снаружи, попытки подмены/терминирования в других точках
+* **IPv6**: если есть AAAA и он указывает не туда, роутер может предпочесть IPv6: помните, что поддержка v6 нестабильна и не рекомендуется в prod
+* **DoH/DoT** на роутере: он может резолвить не тем резолвером, которым вы проверяли
+
+Минимальная гигиена:
+
+* контролировать A/AAAA,
+* держать TTL разумным,
+* проверять, каким резолвером пользуется именно роутер,
+* при необходимости отключить/ограничить destination override
+
+---
+
+## Итог
+
+В режиме TLS-fronting с xray-core/sing-box как L7/TLS-роутером **SNI становится приоритетным "source-of-truth" для маршрутизации**
+
+Если фронтинг-домен по DNS указывает не на IP telemt, роутер честно уводит трафик на "оригинальный" сайт, потому что он строит исходящее соединение "по SNI"
+
+Надёжное решение для этого кейса:
+
+* использовать **свой домен** для фронтинга,
+* направить его **A/AAAA** на IP telemt,
+* поднять на telemt **TLS-сервис с Let’s Encrypt сертификатом** под этот домен,
+* (желательно) держать **сайт-заглушку**, чтобы 443 выглядел как обычный HTTPS

install.sh

@@ -0,0 +1,73 @@
+sudo bash -c '
+set -e
+
+# --- Проверка на существующую установку ---
+if systemctl list-unit-files | grep -q telemt.service; then
+    # --- РЕЖИМ ОБНОВЛЕНИЯ ---
+    echo "--- Обнаружена существующая установка Telemt. Запускаю обновление... ---"
+
+    echo "[*] Остановка службы telemt..."
+    systemctl stop telemt || true # Игнорируем ошибку, если служба уже остановлена
+
+    echo "[1/2] Скачивание последней версии Telemt..."
+    wget -qO- "https://github.com/telemt/telemt/releases/latest/download/telemt-$(uname -m)-linux-$(ldd --version 2>&1 | grep -iq musl && echo musl || echo gnu).tar.gz" | tar -xz
+
+    echo "[1/2] Замена исполняемого файла в /usr/local/bin..."
+    mv telemt /usr/local/bin/telemt
+    chmod +x /usr/local/bin/telemt
+
+    echo "[2/2] Запуск службы..."
+    systemctl start telemt
+
+    echo "--- Обновление Telemt успешно завершено! ---"
+    echo
+    echo "Для проверки статуса службы выполните:"
+    echo "   systemctl status telemt"
+
+else
+    # --- РЕЖИМ НОВОЙ УСТАНОВКИ ---
+    echo "--- Начало автоматической установки Telemt ---"
+
+    # Шаг 1: Скачивание и установка бинарного файла
+    echo "[1/5] Скачивание последней версии Telemt..."
+    wget -qO- "https://github.com/telemt/telemt/releases/latest/download/telemt-$(uname -m)-linux-$(ldd --version 2>&1 | grep -iq musl && echo musl || echo gnu).tar.gz" | tar -xz
+
+    echo "[1/5] Перемещение исполняемого файла в /usr/local/bin и установка прав..."
+    mv telemt /usr/local/bin/telemt
+    chmod +x /usr/local/bin/telemt
+
+    # Шаг 2: Генерация секрета
+    echo "[2/5] Генерация секретного ключа..."
+    SECRET=$(openssl rand -hex 16)
+
+    # Шаг 3: Создание файла конфигурации
+    echo "[3/5] Создание файла конфигурации /etc/telemt.toml..."
+    printf "# === General Settings ===\n[general]\n[general.modes]\nclassic = false\nsecure = false\ntls = true\n\n# === Anti-Censorship & Masking ===\n[censorship]\n# !!! ВАЖНО: Замените на ваш домен или домен, который вы хотите использовать для маскировки !!!\ntls_domain = \"petrovich.ru\"\n\n[access.users]\nhello = \"%s\"\n" "$SECRET" > /etc/telemt.toml
+
+    # Шаг 4: Создание службы Systemd
+    echo "[4/5] Создание службы systemd..."
+    printf "[Unit]\nDescription=Telemt Proxy\nAfter=network.target\n\n[Service]\nType=simple\nExecStart=/usr/local/bin/telemt /etc/telemt.toml\nRestart=on-failure\nRestartSec=5\nLimitNOFILE=65536\n\n[Install]\nWantedBy=multi-user.target\n" > /etc/systemd/system/telemt.service
+
+    # Шаг 5: Запуск службы
+    echo "[5/5] Перезагрузка systemd, запуск и включение службы telemt..."
+    systemctl daemon-reload
+    systemctl start telemt
+    systemctl enable telemt
+
+    echo "--- Установка и запуск Telemt успешно завершены! ---"
+    echo
+    echo "ВАЖНАЯ ИНФОРМАЦИЯ:"
+    echo "==================="
+    echo "1. Вам НЕОБХОДИМО отредактировать файл /etc/telemt.toml и заменить '\''petrovich.ru'\'' на другой домен"
+    echo "   с помощью команды:"
+    echo "   nano /etc/telemt.toml"
+    echo "   После редактирования файла перезапустите службу командой:"
+    echo "   sudo systemctl restart telemt"
+    echo
+    echo "2. Для проверки статуса службы выполните команду:"
+    echo "   systemctl status telemt"
+    echo
+    echo "3. Для получения ссылок на подключение выполните команду:"
+    echo "   journalctl -u telemt -n -g '\''links'\'' --no-pager -o cat | tac"
+fi
+'

src/config/defaults.rs

@@ -8,6 +8,10 @@ const DEFAULT_STUN_TCP_FALLBACK: bool = true;
 const DEFAULT_MIDDLE_PROXY_WARM_STANDBY: usize = 16;
 const DEFAULT_ME_RECONNECT_MAX_CONCURRENT_PER_DC: u32 = 8;
 const DEFAULT_ME_RECONNECT_FAST_RETRY_COUNT: u32 = 16;
+const DEFAULT_ME_SINGLE_ENDPOINT_SHADOW_WRITERS: u8 = 2;
+const DEFAULT_ME_ADAPTIVE_FLOOR_IDLE_SECS: u64 = 90;
+const DEFAULT_ME_ADAPTIVE_FLOOR_MIN_WRITERS_SINGLE_ENDPOINT: u8 = 1;
+const DEFAULT_ME_ADAPTIVE_FLOOR_RECOVER_GRACE_SECS: u64 = 180;
 const DEFAULT_UPSTREAM_CONNECT_RETRY_ATTEMPTS: u32 = 3;
 const DEFAULT_UPSTREAM_UNHEALTHY_FAIL_THRESHOLD: u32 = 4;
 const DEFAULT_LISTEN_ADDR_IPV6: &str = "::";
@@ -129,11 +133,11 @@ pub(crate) fn default_middle_proxy_warm_standby() -> usize {
 }
 
 pub(crate) fn default_keepalive_interval() -> u64 {
-    25
+    8
 }
 
 pub(crate) fn default_keepalive_jitter() -> u64 {
-    5
+    2
 }
 
 pub(crate) fn default_warmup_step_delay_ms() -> u64 {
@@ -160,6 +164,42 @@ pub(crate) fn default_me_reconnect_fast_retry_count() -> u32 {
     DEFAULT_ME_RECONNECT_FAST_RETRY_COUNT
 }
 
+pub(crate) fn default_me_single_endpoint_shadow_writers() -> u8 {
+    DEFAULT_ME_SINGLE_ENDPOINT_SHADOW_WRITERS
+}
+
+pub(crate) fn default_me_single_endpoint_outage_mode_enabled() -> bool {
+    true
+}
+
+pub(crate) fn default_me_single_endpoint_outage_disable_quarantine() -> bool {
+    true
+}
+
+pub(crate) fn default_me_single_endpoint_outage_backoff_min_ms() -> u64 {
+    250
+}
+
+pub(crate) fn default_me_single_endpoint_outage_backoff_max_ms() -> u64 {
+    3000
+}
+
+pub(crate) fn default_me_single_endpoint_shadow_rotate_every_secs() -> u64 {
+    900
+}
+
+pub(crate) fn default_me_adaptive_floor_idle_secs() -> u64 {
+    DEFAULT_ME_ADAPTIVE_FLOOR_IDLE_SECS
+}
+
+pub(crate) fn default_me_adaptive_floor_min_writers_single_endpoint() -> u8 {
+    DEFAULT_ME_ADAPTIVE_FLOOR_MIN_WRITERS_SINGLE_ENDPOINT
+}
+
+pub(crate) fn default_me_adaptive_floor_recover_grace_secs() -> u64 {
+    DEFAULT_ME_ADAPTIVE_FLOOR_RECOVER_GRACE_SECS
+}
+
 pub(crate) fn default_upstream_connect_retry_attempts() -> u32 {
     DEFAULT_UPSTREAM_CONNECT_RETRY_ATTEMPTS
 }
@@ -277,6 +317,18 @@ pub(crate) fn default_me_reinit_every_secs() -> u64 {
     15 * 60
 }
 
+pub(crate) fn default_me_reinit_singleflight() -> bool {
+    true
+}
+
+pub(crate) fn default_me_reinit_trigger_channel() -> usize {
+    64
+}
+
+pub(crate) fn default_me_reinit_coalesce_window_ms() -> u64 {
+    200
+}
+
 pub(crate) fn default_me_hardswap_warmup_delay_min_ms() -> u64 {
     1000
 }
@@ -301,6 +353,18 @@ pub(crate) fn default_me_config_apply_cooldown_secs() -> u64 {
     300
 }
 
+pub(crate) fn default_me_snapshot_require_http_2xx() -> bool {
+    true
+}
+
+pub(crate) fn default_me_snapshot_reject_empty_map() -> bool {
+    true
+}
+
+pub(crate) fn default_me_snapshot_min_proxy_for_lines() -> u32 {
+    1
+}
+
 pub(crate) fn default_proxy_secret_stable_snapshots() -> u8 {
     2
 }
@@ -309,6 +373,10 @@ pub(crate) fn default_proxy_secret_rotate_runtime() -> bool {
     true
 }
 
+pub(crate) fn default_me_secret_atomic_snapshot() -> bool {
+    true
+}
+
 pub(crate) fn default_proxy_secret_len_max() -> usize {
     256
 }
@@ -321,10 +389,18 @@ pub(crate) fn default_me_pool_drain_ttl_secs() -> u64 {
     90
 }
 
+pub(crate) fn default_me_bind_stale_ttl_secs() -> u64 {
+    default_me_pool_drain_ttl_secs()
+}
+
 pub(crate) fn default_me_pool_min_fresh_ratio() -> f32 {
     0.8
 }
 
+pub(crate) fn default_me_deterministic_writer_sort() -> bool {
+    true
+}
+
 pub(crate) fn default_hardswap() -> bool {
     true
 }

src/config/hot_reload.rs

@@ -4,21 +4,22 @@
 //!
 //! # What can be reloaded without restart
 //!
-//! | Section   | Field                         | Effect                            |
-//! |-----------|-------------------------------|-----------------------------------|
-//! | `general` | `log_level`                   | Filter updated via `log_level_tx` |
-//! | `general` | `ad_tag`                      | Passed on next connection         |
-//! | `general` | `middle_proxy_pool_size`      | Passed on next connection         |
-//! | `general` | `me_keepalive_*`              | Passed on next connection         |
-//! | `general` | `desync_all_full`             | Applied immediately               |
-//! | `general` | `update_every`                | Applied to ME updater immediately |
-//! | `general` | `hardswap`                    | Applied on next ME map update     |
-//! | `general` | `me_pool_drain_ttl_secs`      | Applied on next ME map update     |
-//! | `general` | `me_pool_min_fresh_ratio`     | Applied on next ME map update     |
-//! | `general` | `me_reinit_drain_timeout_secs`| Applied on next ME map update     |
-//! | `general` | `telemetry` / `me_*_policy`   | Applied immediately               |
-//! | `network` | `dns_overrides`               | Applied immediately               |
-//! | `access`  | All user/quota fields         | Effective immediately             |
+//! | Section   | Field                          | Effect                                         |
+//! |-----------|--------------------------------|------------------------------------------------|
+//! | `general` | `log_level`                    | Filter updated via `log_level_tx`              |
+//! | `access`  | `user_ad_tags`                 | Passed on next connection                      |
+//! | `general` | `ad_tag`                       | Passed on next connection (fallback per-user)  |
+//! | `general` | `middle_proxy_pool_size`       | Passed on next connection                      |
+//! | `general` | `me_keepalive_*`               | Passed on next connection                      |
+//! | `general` | `desync_all_full`              | Applied immediately                            |
+//! | `general` | `update_every`                 | Applied to ME updater immediately              |
+//! | `general` | `hardswap`                     | Applied on next ME map update                  |
+//! | `general` | `me_pool_drain_ttl_secs`       | Applied on next ME map update                  |
+//! | `general` | `me_pool_min_fresh_ratio`      | Applied on next ME map update                  |
+//! | `general` | `me_reinit_drain_timeout_secs` | Applied on next ME map update                  |
+//! | `general` | `telemetry` / `me_*_policy`    | Applied immediately                            |
+//! | `network` | `dns_overrides`                | Applied immediately                            |
+//! | `access`  | All user/quota fields          | Effective immediately                          |
 //!
 //! Fields that require re-binding sockets (`server.port`, `censorship.*`,
 //! `network.*`, `use_middle_proxy`) are **not** applied; a warning is emitted.
@@ -31,7 +32,7 @@ use notify::{EventKind, RecursiveMode, Watcher, recommended_watcher};
 use tokio::sync::{mpsc, watch};
 use tracing::{error, info, warn};
 
-use crate::config::{LogLevel, MeSocksKdfPolicy, MeTelemetryLevel};
+use crate::config::{LogLevel, MeFloorMode, MeSocksKdfPolicy, MeTelemetryLevel};
 use super::load::ProxyConfig;
 
 // ── Hot fields ────────────────────────────────────────────────────────────────
@@ -57,6 +58,10 @@ pub struct HotFields {
     pub telemetry_user_enabled: bool,
     pub telemetry_me_level: MeTelemetryLevel,
     pub me_socks_kdf_policy: MeSocksKdfPolicy,
+    pub me_floor_mode: MeFloorMode,
+    pub me_adaptive_floor_idle_secs: u64,
+    pub me_adaptive_floor_min_writers_single_endpoint: u8,
+    pub me_adaptive_floor_recover_grace_secs: u64,
     pub me_route_backpressure_base_timeout_ms: u64,
     pub me_route_backpressure_high_timeout_ms: u64,
     pub me_route_backpressure_high_watermark_pct: u8,
@@ -84,6 +89,14 @@ impl HotFields {
             telemetry_user_enabled: cfg.general.telemetry.user_enabled,
             telemetry_me_level: cfg.general.telemetry.me_level,
             me_socks_kdf_policy: cfg.general.me_socks_kdf_policy,
+            me_floor_mode: cfg.general.me_floor_mode,
+            me_adaptive_floor_idle_secs: cfg.general.me_adaptive_floor_idle_secs,
+            me_adaptive_floor_min_writers_single_endpoint: cfg
+                .general
+                .me_adaptive_floor_min_writers_single_endpoint,
+            me_adaptive_floor_recover_grace_secs: cfg
+                .general
+                .me_adaptive_floor_recover_grace_secs,
             me_route_backpressure_base_timeout_ms: cfg.general.me_route_backpressure_base_timeout_ms,
             me_route_backpressure_high_timeout_ms: cfg.general.me_route_backpressure_high_timeout_ms,
             me_route_backpressure_high_watermark_pct: cfg.general.me_route_backpressure_high_watermark_pct,
@@ -207,14 +220,17 @@ fn log_changes(
         log_tx.send(new_hot.log_level.clone()).ok();
     }
 
-    if old_hot.ad_tag != new_hot.ad_tag {
+    if old_hot.access.user_ad_tags != new_hot.access.user_ad_tags {
         info!(
-            "config reload: ad_tag: {} → {}",
-            old_hot.ad_tag.as_deref().unwrap_or("none"),
-            new_hot.ad_tag.as_deref().unwrap_or("none"),
+            "config reload: user_ad_tags updated ({} entries)",
+            new_hot.access.user_ad_tags.len(),
         );
     }
 
+    if old_hot.ad_tag != new_hot.ad_tag {
+        info!("config reload: general.ad_tag updated (applied on next connection)");
+    }
+
     if old_hot.dns_overrides != new_hot.dns_overrides {
         info!(
             "config reload: network.dns_overrides updated ({} entries)",
@@ -305,6 +321,22 @@ fn log_changes(
         );
     }
 
+    if old_hot.me_floor_mode != new_hot.me_floor_mode
+        || old_hot.me_adaptive_floor_idle_secs != new_hot.me_adaptive_floor_idle_secs
+        || old_hot.me_adaptive_floor_min_writers_single_endpoint
+            != new_hot.me_adaptive_floor_min_writers_single_endpoint
+        || old_hot.me_adaptive_floor_recover_grace_secs
+            != new_hot.me_adaptive_floor_recover_grace_secs
+    {
+        info!(
+            "config reload: me_floor: mode={:?} idle={}s min_single={} recover_grace={}s",
+            new_hot.me_floor_mode,
+            new_hot.me_adaptive_floor_idle_secs,
+            new_hot.me_adaptive_floor_min_writers_single_endpoint,
+            new_hot.me_adaptive_floor_recover_grace_secs,
+        );
+    }
+
     if old_hot.me_route_backpressure_base_timeout_ms
         != new_hot.me_route_backpressure_base_timeout_ms
         || old_hot.me_route_backpressure_high_timeout_ms

src/config/load.rs

@@ -255,6 +255,41 @@ impl ProxyConfig {
             ));
         }
 
+        if config.general.me_single_endpoint_shadow_writers > 32 {
+            return Err(ProxyError::Config(
+                "general.me_single_endpoint_shadow_writers must be within [0, 32]".to_string(),
+            ));
+        }
+
+        if config.general.me_adaptive_floor_min_writers_single_endpoint == 0
+            || config.general.me_adaptive_floor_min_writers_single_endpoint > 32
+        {
+            return Err(ProxyError::Config(
+                "general.me_adaptive_floor_min_writers_single_endpoint must be within [1, 32]"
+                    .to_string(),
+            ));
+        }
+
+        if config.general.me_single_endpoint_outage_backoff_min_ms == 0 {
+            return Err(ProxyError::Config(
+                "general.me_single_endpoint_outage_backoff_min_ms must be > 0".to_string(),
+            ));
+        }
+
+        if config.general.me_single_endpoint_outage_backoff_max_ms == 0 {
+            return Err(ProxyError::Config(
+                "general.me_single_endpoint_outage_backoff_max_ms must be > 0".to_string(),
+            ));
+        }
+
+        if config.general.me_single_endpoint_outage_backoff_min_ms
+            > config.general.me_single_endpoint_outage_backoff_max_ms
+        {
+            return Err(ProxyError::Config(
+                "general.me_single_endpoint_outage_backoff_min_ms must be <= general.me_single_endpoint_outage_backoff_max_ms".to_string(),
+            ));
+        }
+
         if config.general.beobachten_minutes == 0 {
             return Err(ProxyError::Config(
                 "general.beobachten_minutes must be > 0".to_string(),
@@ -305,12 +340,24 @@ impl ProxyConfig {
             ));
         }
 
+        if config.general.me_snapshot_min_proxy_for_lines == 0 {
+            return Err(ProxyError::Config(
+                "general.me_snapshot_min_proxy_for_lines must be > 0".to_string(),
+            ));
+        }
+
         if config.general.proxy_secret_stable_snapshots == 0 {
             return Err(ProxyError::Config(
                 "general.proxy_secret_stable_snapshots must be > 0".to_string(),
             ));
         }
 
+        if config.general.me_reinit_trigger_channel == 0 {
+            return Err(ProxyError::Config(
+                "general.me_reinit_trigger_channel must be > 0".to_string(),
+            ));
+        }
+
         if !(32..=4096).contains(&config.general.proxy_secret_len_max) {
             return Err(ProxyError::Config(
                 "general.proxy_secret_len_max must be within [32, 4096]".to_string(),
@@ -532,15 +579,16 @@ impl ProxyConfig {
             )));
         }
 
-        if let Some(tag) = &self.general.ad_tag {
+        for (user, tag) in &self.access.user_ad_tags {
             let zeros = "00000000000000000000000000000000";
             if !is_valid_ad_tag(tag) {
-                return Err(ProxyError::Config(
-                    "general.ad_tag must be exactly 32 hex characters".to_string(),
-                ));
+                return Err(ProxyError::Config(format!(
+                    "access.user_ad_tags['{}'] must be exactly 32 hex characters",
+                    user
+                )));
             }
             if tag == zeros {
-                warn!("ad_tag is all zeros; register a valid proxy tag via @MTProxybot to enable sponsored channel");
+                warn!(user = %user, "user ad_tag is all zeros; register a valid proxy tag via @MTProxybot to enable sponsored channel");
             }
         }
 
@@ -579,6 +627,43 @@ mod tests {
             cfg.general.me_reconnect_fast_retry_count,
             default_me_reconnect_fast_retry_count()
         );
+        assert_eq!(
+            cfg.general.me_single_endpoint_shadow_writers,
+            default_me_single_endpoint_shadow_writers()
+        );
+        assert_eq!(
+            cfg.general.me_single_endpoint_outage_mode_enabled,
+            default_me_single_endpoint_outage_mode_enabled()
+        );
+        assert_eq!(
+            cfg.general.me_single_endpoint_outage_disable_quarantine,
+            default_me_single_endpoint_outage_disable_quarantine()
+        );
+        assert_eq!(
+            cfg.general.me_single_endpoint_outage_backoff_min_ms,
+            default_me_single_endpoint_outage_backoff_min_ms()
+        );
+        assert_eq!(
+            cfg.general.me_single_endpoint_outage_backoff_max_ms,
+            default_me_single_endpoint_outage_backoff_max_ms()
+        );
+        assert_eq!(
+            cfg.general.me_single_endpoint_shadow_rotate_every_secs,
+            default_me_single_endpoint_shadow_rotate_every_secs()
+        );
+        assert_eq!(cfg.general.me_floor_mode, MeFloorMode::default());
+        assert_eq!(
+            cfg.general.me_adaptive_floor_idle_secs,
+            default_me_adaptive_floor_idle_secs()
+        );
+        assert_eq!(
+            cfg.general.me_adaptive_floor_min_writers_single_endpoint,
+            default_me_adaptive_floor_min_writers_single_endpoint()
+        );
+        assert_eq!(
+            cfg.general.me_adaptive_floor_recover_grace_secs,
+            default_me_adaptive_floor_recover_grace_secs()
+        );
         assert_eq!(
             cfg.general.upstream_connect_retry_attempts,
             default_upstream_connect_retry_attempts()
@@ -617,6 +702,43 @@ mod tests {
             general.me_reconnect_fast_retry_count,
             default_me_reconnect_fast_retry_count()
         );
+        assert_eq!(
+            general.me_single_endpoint_shadow_writers,
+            default_me_single_endpoint_shadow_writers()
+        );
+        assert_eq!(
+            general.me_single_endpoint_outage_mode_enabled,
+            default_me_single_endpoint_outage_mode_enabled()
+        );
+        assert_eq!(
+            general.me_single_endpoint_outage_disable_quarantine,
+            default_me_single_endpoint_outage_disable_quarantine()
+        );
+        assert_eq!(
+            general.me_single_endpoint_outage_backoff_min_ms,
+            default_me_single_endpoint_outage_backoff_min_ms()
+        );
+        assert_eq!(
+            general.me_single_endpoint_outage_backoff_max_ms,
+            default_me_single_endpoint_outage_backoff_max_ms()
+        );
+        assert_eq!(
+            general.me_single_endpoint_shadow_rotate_every_secs,
+            default_me_single_endpoint_shadow_rotate_every_secs()
+        );
+        assert_eq!(general.me_floor_mode, MeFloorMode::default());
+        assert_eq!(
+            general.me_adaptive_floor_idle_secs,
+            default_me_adaptive_floor_idle_secs()
+        );
+        assert_eq!(
+            general.me_adaptive_floor_min_writers_single_endpoint,
+            default_me_adaptive_floor_min_writers_single_endpoint()
+        );
+        assert_eq!(
+            general.me_adaptive_floor_recover_grace_secs,
+            default_me_adaptive_floor_recover_grace_secs()
+        );
         assert_eq!(
             general.upstream_connect_retry_attempts,
             default_upstream_connect_retry_attempts()
@@ -801,6 +923,93 @@ mod tests {
         let _ = std::fs::remove_file(path);
     }
 
+    #[test]
+    fn me_single_endpoint_outage_backoff_range_is_validated() {
+        let toml = r#"
+            [general]
+            me_single_endpoint_outage_backoff_min_ms = 4000
+            me_single_endpoint_outage_backoff_max_ms = 3000
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_me_single_endpoint_outage_backoff_range_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let err = ProxyConfig::load(&path).unwrap_err().to_string();
+        assert!(err.contains(
+            "general.me_single_endpoint_outage_backoff_min_ms must be <= general.me_single_endpoint_outage_backoff_max_ms"
+        ));
+        let _ = std::fs::remove_file(path);
+    }
+
+    #[test]
+    fn me_single_endpoint_shadow_writers_too_large_is_rejected() {
+        let toml = r#"
+            [general]
+            me_single_endpoint_shadow_writers = 33
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_me_single_endpoint_shadow_writers_limit_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let err = ProxyConfig::load(&path).unwrap_err().to_string();
+        assert!(err.contains("general.me_single_endpoint_shadow_writers must be within [0, 32]"));
+        let _ = std::fs::remove_file(path);
+    }
+
+    #[test]
+    fn me_adaptive_floor_min_writers_out_of_range_is_rejected() {
+        let toml = r#"
+            [general]
+            me_adaptive_floor_min_writers_single_endpoint = 0
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_me_adaptive_floor_min_writers_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_adaptive_floor_min_writers_single_endpoint must be within [1, 32]"
+            )
+        );
+        let _ = std::fs::remove_file(path);
+    }
+
+    #[test]
+    fn me_floor_mode_adaptive_is_parsed() {
+        let toml = r#"
+            [general]
+            me_floor_mode = "adaptive"
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_me_floor_mode_adaptive_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let cfg = ProxyConfig::load(&path).unwrap();
+        assert_eq!(cfg.general.me_floor_mode, MeFloorMode::Adaptive);
+        let _ = std::fs::remove_file(path);
+    }
+
     #[test]
     fn upstream_connect_retry_attempts_zero_is_rejected() {
         let toml = r#"
@@ -1100,6 +1309,27 @@ mod tests {
         let _ = std::fs::remove_file(path);
     }
 
+    #[test]
+    fn invalid_user_ad_tag_reports_access_user_ad_tags_key() {
+        let toml = r#"
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            alice = "00000000000000000000000000000000"
+
+            [access.user_ad_tags]
+            alice = "not_hex"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_invalid_user_ad_tag_message_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let cfg = ProxyConfig::load(&path).unwrap();
+        let err = cfg.validate().unwrap_err().to_string();
+        assert!(err.contains("access.user_ad_tags['alice'] must be exactly 32 hex characters"));
+        let _ = std::fs::remove_file(path);
+    }
+
     #[test]
     fn invalid_dns_override_is_rejected() {
         let toml = r#"

src/config/types.rs

@@ -130,6 +130,59 @@ impl MeSocksKdfPolicy {
     }
 }
 
+/// Stale ME writer bind policy during drain window.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "lowercase")]
+pub enum MeBindStaleMode {
+    Never,
+    #[default]
+    Ttl,
+    Always,
+}
+
+impl MeBindStaleMode {
+    pub fn as_u8(self) -> u8 {
+        match self {
+            MeBindStaleMode::Never => 0,
+            MeBindStaleMode::Ttl => 1,
+            MeBindStaleMode::Always => 2,
+        }
+    }
+
+    pub fn from_u8(raw: u8) -> Self {
+        match raw {
+            0 => MeBindStaleMode::Never,
+            2 => MeBindStaleMode::Always,
+            _ => MeBindStaleMode::Ttl,
+        }
+    }
+}
+
+/// Middle-End writer floor policy mode.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "lowercase")]
+pub enum MeFloorMode {
+    #[default]
+    Static,
+    Adaptive,
+}
+
+impl MeFloorMode {
+    pub fn as_u8(self) -> u8 {
+        match self {
+            MeFloorMode::Static => 0,
+            MeFloorMode::Adaptive => 1,
+        }
+    }
+
+    pub fn from_u8(raw: u8) -> Self {
+        match raw {
+            1 => MeFloorMode::Adaptive,
+            _ => MeFloorMode::Static,
+        }
+    }
+}
+
 /// Telemetry controls for hot-path counters and ME diagnostics.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct TelemetryConfig {
@@ -247,14 +300,15 @@ pub struct GeneralConfig {
     #[serde(default = "default_true")]
     pub use_middle_proxy: bool,
 
-    #[serde(default)]
-    pub ad_tag: Option<String>,
-
     /// Path to proxy-secret binary file (auto-downloaded if absent).
     /// Infrastructure secret from https://core.telegram.org/getProxySecret.
     #[serde(default = "default_proxy_secret_path")]
     pub proxy_secret_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>,
+
     /// Public IP override for middle-proxy NAT environments.
     /// When set, this IP is used in ME key derivation and RPC_PROXY_REQ "our_addr".
     #[serde(default)]
@@ -365,6 +419,47 @@ pub struct GeneralConfig {
     #[serde(default = "default_me_reconnect_fast_retry_count")]
     pub me_reconnect_fast_retry_count: u32,
 
+    /// Number of additional reserve writers for DC groups with exactly one endpoint.
+    #[serde(default = "default_me_single_endpoint_shadow_writers")]
+    pub me_single_endpoint_shadow_writers: u8,
+
+    /// Enable aggressive outage recovery mode for single-endpoint DC groups.
+    #[serde(default = "default_me_single_endpoint_outage_mode_enabled")]
+    pub me_single_endpoint_outage_mode_enabled: bool,
+
+    /// Ignore endpoint quarantine while in single-endpoint outage mode.
+    #[serde(default = "default_me_single_endpoint_outage_disable_quarantine")]
+    pub me_single_endpoint_outage_disable_quarantine: bool,
+
+    /// Minimum reconnect backoff in ms for single-endpoint outage mode.
+    #[serde(default = "default_me_single_endpoint_outage_backoff_min_ms")]
+    pub me_single_endpoint_outage_backoff_min_ms: u64,
+
+    /// Maximum reconnect backoff in ms for single-endpoint outage mode.
+    #[serde(default = "default_me_single_endpoint_outage_backoff_max_ms")]
+    pub me_single_endpoint_outage_backoff_max_ms: u64,
+
+    /// Periodic shadow writer rotation interval in seconds for single-endpoint DC groups.
+    /// Set to 0 to disable periodic shadow rotation.
+    #[serde(default = "default_me_single_endpoint_shadow_rotate_every_secs")]
+    pub me_single_endpoint_shadow_rotate_every_secs: u64,
+
+    /// Floor policy mode for ME writer targets.
+    #[serde(default)]
+    pub me_floor_mode: MeFloorMode,
+
+    /// Idle time in seconds before adaptive floor can reduce single-endpoint writer target.
+    #[serde(default = "default_me_adaptive_floor_idle_secs")]
+    pub me_adaptive_floor_idle_secs: u64,
+
+    /// Minimum writer target for single-endpoint DC groups in adaptive floor mode.
+    #[serde(default = "default_me_adaptive_floor_min_writers_single_endpoint")]
+    pub me_adaptive_floor_min_writers_single_endpoint: u8,
+
+    /// Grace period in seconds to hold static floor after activity in adaptive mode.
+    #[serde(default = "default_me_adaptive_floor_recover_grace_secs")]
+    pub me_adaptive_floor_recover_grace_secs: u64,
+
     /// Connect attempts for the selected upstream before returning error/fallback.
     #[serde(default = "default_upstream_connect_retry_attempts")]
     pub upstream_connect_retry_attempts: u32,
@@ -453,6 +548,18 @@ pub struct GeneralConfig {
     #[serde(default = "default_me_config_apply_cooldown_secs")]
     pub me_config_apply_cooldown_secs: u64,
 
+    /// Ensure getProxyConfig snapshots are applied only for 2xx HTTP responses.
+    #[serde(default = "default_me_snapshot_require_http_2xx")]
+    pub me_snapshot_require_http_2xx: bool,
+
+    /// Reject empty getProxyConfig snapshots instead of marking them applied.
+    #[serde(default = "default_me_snapshot_reject_empty_map")]
+    pub me_snapshot_reject_empty_map: bool,
+
+    /// Minimum parsed `proxy_for` rows required to accept a snapshot.
+    #[serde(default = "default_me_snapshot_min_proxy_for_lines")]
+    pub me_snapshot_min_proxy_for_lines: u32,
+
     /// Number of identical getProxySecret snapshots required before runtime secret rotation.
     #[serde(default = "default_proxy_secret_stable_snapshots")]
     pub proxy_secret_stable_snapshots: u8,
@@ -461,6 +568,10 @@ pub struct GeneralConfig {
     #[serde(default = "default_proxy_secret_rotate_runtime")]
     pub proxy_secret_rotate_runtime: bool,
 
+    /// Keep key-selector and secret bytes from one snapshot during ME handshake.
+    #[serde(default = "default_me_secret_atomic_snapshot")]
+    pub me_secret_atomic_snapshot: bool,
+
     /// Maximum allowed proxy-secret length in bytes for startup and runtime refresh.
     #[serde(default = "default_proxy_secret_len_max")]
     pub proxy_secret_len_max: usize,
@@ -470,6 +581,14 @@ pub struct GeneralConfig {
     #[serde(default = "default_me_pool_drain_ttl_secs")]
     pub me_pool_drain_ttl_secs: u64,
 
+    /// Policy for new binds on stale draining writers.
+    #[serde(default)]
+    pub me_bind_stale_mode: MeBindStaleMode,
+
+    /// TTL for stale bind allowance when `me_bind_stale_mode = \"ttl\"`.
+    #[serde(default = "default_me_bind_stale_ttl_secs")]
+    pub me_bind_stale_ttl_secs: u64,
+
     /// Minimum desired-DC coverage ratio required before draining stale writers.
     /// Range: 0.0..=1.0.
     #[serde(default = "default_me_pool_min_fresh_ratio")]
@@ -490,6 +609,22 @@ pub struct GeneralConfig {
     #[serde(default = "default_proxy_config_reload_secs")]
     pub proxy_config_auto_reload_secs: u64,
 
+    /// Serialize ME reinit cycles across all trigger sources.
+    #[serde(default = "default_me_reinit_singleflight")]
+    pub me_reinit_singleflight: bool,
+
+    /// Trigger queue capacity for reinit scheduler.
+    #[serde(default = "default_me_reinit_trigger_channel")]
+    pub me_reinit_trigger_channel: usize,
+
+    /// Trigger coalescing window before starting a reinit cycle.
+    #[serde(default = "default_me_reinit_coalesce_window_ms")]
+    pub me_reinit_coalesce_window_ms: u64,
+
+    /// Deterministic candidate sort for ME writer binding path.
+    #[serde(default = "default_me_deterministic_writer_sort")]
+    pub me_deterministic_writer_sort: bool,
+
     /// Enable NTP drift check at startup.
     #[serde(default = "default_ntp_check")]
     pub ntp_check: bool,
@@ -534,6 +669,16 @@ impl Default for GeneralConfig {
             me_reconnect_backoff_base_ms: default_reconnect_backoff_base_ms(),
             me_reconnect_backoff_cap_ms: default_reconnect_backoff_cap_ms(),
             me_reconnect_fast_retry_count: default_me_reconnect_fast_retry_count(),
+            me_single_endpoint_shadow_writers: default_me_single_endpoint_shadow_writers(),
+            me_single_endpoint_outage_mode_enabled: default_me_single_endpoint_outage_mode_enabled(),
+            me_single_endpoint_outage_disable_quarantine: default_me_single_endpoint_outage_disable_quarantine(),
+            me_single_endpoint_outage_backoff_min_ms: default_me_single_endpoint_outage_backoff_min_ms(),
+            me_single_endpoint_outage_backoff_max_ms: default_me_single_endpoint_outage_backoff_max_ms(),
+            me_single_endpoint_shadow_rotate_every_secs: default_me_single_endpoint_shadow_rotate_every_secs(),
+            me_floor_mode: MeFloorMode::default(),
+            me_adaptive_floor_idle_secs: default_me_adaptive_floor_idle_secs(),
+            me_adaptive_floor_min_writers_single_endpoint: default_me_adaptive_floor_min_writers_single_endpoint(),
+            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_unhealthy_fail_threshold: default_upstream_unhealthy_fail_threshold(),
@@ -564,14 +709,24 @@ impl Default for GeneralConfig {
             me_hardswap_warmup_pass_backoff_base_ms: default_me_hardswap_warmup_pass_backoff_base_ms(),
             me_config_stable_snapshots: default_me_config_stable_snapshots(),
             me_config_apply_cooldown_secs: default_me_config_apply_cooldown_secs(),
+            me_snapshot_require_http_2xx: default_me_snapshot_require_http_2xx(),
+            me_snapshot_reject_empty_map: default_me_snapshot_reject_empty_map(),
+            me_snapshot_min_proxy_for_lines: default_me_snapshot_min_proxy_for_lines(),
             proxy_secret_stable_snapshots: default_proxy_secret_stable_snapshots(),
             proxy_secret_rotate_runtime: default_proxy_secret_rotate_runtime(),
+            me_secret_atomic_snapshot: default_me_secret_atomic_snapshot(),
             proxy_secret_len_max: default_proxy_secret_len_max(),
             me_pool_drain_ttl_secs: default_me_pool_drain_ttl_secs(),
+            me_bind_stale_mode: MeBindStaleMode::default(),
+            me_bind_stale_ttl_secs: default_me_bind_stale_ttl_secs(),
             me_pool_min_fresh_ratio: default_me_pool_min_fresh_ratio(),
             me_reinit_drain_timeout_secs: default_me_reinit_drain_timeout_secs(),
             proxy_secret_auto_reload_secs: default_proxy_secret_reload_secs(),
             proxy_config_auto_reload_secs: default_proxy_config_reload_secs(),
+            me_reinit_singleflight: default_me_reinit_singleflight(),
+            me_reinit_trigger_channel: default_me_reinit_trigger_channel(),
+            me_reinit_coalesce_window_ms: default_me_reinit_coalesce_window_ms(),
+            me_deterministic_writer_sort: default_me_deterministic_writer_sort(),
             ntp_check: default_ntp_check(),
             ntp_servers: default_ntp_servers(),
             auto_degradation_enabled: default_true(),
@@ -807,6 +962,10 @@ pub struct AccessConfig {
     #[serde(default = "default_access_users")]
     pub users: HashMap<String, String>,
 
+    /// Per-user ad_tag (32 hex chars from @MTProxybot).
+    #[serde(default)]
+    pub user_ad_tags: HashMap<String, String>,
+
     #[serde(default)]
     pub user_max_tcp_conns: HashMap<String, usize>,
 
@@ -833,6 +992,7 @@ impl Default for AccessConfig {
     fn default() -> Self {
         Self {
             users: default_access_users(),
+            user_ad_tags: HashMap::new(),
             user_max_tcp_conns: HashMap::new(),
             user_expirations: HashMap::new(),
             user_data_quota: HashMap::new(),

src/main.rs

@@ -8,7 +8,7 @@ use std::time::Duration;
 use rand::Rng;
 use tokio::net::TcpListener;
 use tokio::signal;
-use tokio::sync::Semaphore;
+use tokio::sync::{Semaphore, mpsc};
 use tracing::{debug, error, info, warn};
 use tracing_subscriber::{EnvFilter, fmt, prelude::*, reload};
 #[cfg(unix)]
@@ -40,7 +40,7 @@ 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, format_sample_line,
+    MePool, fetch_proxy_config, run_me_ping, MePingFamily, MePingSample, MeReinitTrigger, format_sample_line,
     format_me_route,
 };
 use crate::transport::{ListenOptions, UpstreamManager, create_listener, find_listener_processes};
@@ -448,7 +448,7 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
             info!("Middle-proxy STUN probing disabled by network.stun_use=false");
         }
 
-        // ad_tag (proxy_tag) for advertising
+        // Global ad_tag (pool default). Used when user has no per-user tag in access.user_ad_tags.
         let proxy_tag = config
             .general
             .ad_tag
@@ -538,6 +538,16 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
                     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(),
@@ -546,6 +556,10 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
                     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,
@@ -770,12 +784,14 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
     // Background tasks
     let um_clone = upstream_manager.clone();
     let decision_clone = decision.clone();
+    let dc_overrides_for_health = config.dc_overrides.clone();
     tokio::spawn(async move {
         um_clone
             .run_health_checks(
                 prefer_ipv6,
                 decision_clone.ipv4_dc,
                 decision_clone.ipv6_dc,
+                dc_overrides_for_health,
             )
             .await;
     });
@@ -847,26 +863,43 @@ async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
     });
 
     if let Some(ref pool) = me_pool {
-        let pool_clone = pool.clone();
-        let rng_clone = rng.clone();
-        let config_rx_clone = config_rx.clone();
+        let reinit_trigger_capacity = config
+            .general
+            .me_reinit_trigger_channel
+            .max(1);
+        let (reinit_tx, reinit_rx) = mpsc::channel::<MeReinitTrigger>(reinit_trigger_capacity);
+
+        let pool_clone_sched = pool.clone();
+        let rng_clone_sched = rng.clone();
+        let config_rx_clone_sched = config_rx.clone();
         tokio::spawn(async move {
-            crate::transport::middle_proxy::me_config_updater(
-                pool_clone,
-                rng_clone,
-                config_rx_clone,
+            crate::transport::middle_proxy::me_reinit_scheduler(
+                pool_clone_sched,
+                rng_clone_sched,
+                config_rx_clone_sched,
+                reinit_rx,
+            )
+            .await;
+        });
+
+        let pool_clone = pool.clone();
+        let config_rx_clone = config_rx.clone();
+        let reinit_tx_updater = reinit_tx.clone();
+        tokio::spawn(async move {
+            crate::transport::middle_proxy::me_config_updater(
+                pool_clone,
+                config_rx_clone,
+                reinit_tx_updater,
             )
             .await;
         });
 
-        let pool_clone_rot = pool.clone();
-        let rng_clone_rot = rng.clone();
         let config_rx_clone_rot = config_rx.clone();
+        let reinit_tx_rotation = reinit_tx.clone();
         tokio::spawn(async move {
             crate::transport::middle_proxy::me_rotation_task(
-                pool_clone_rot,
-                rng_clone_rot,
                 config_rx_clone_rot,
+                reinit_tx_rotation,
             )
             .await;
         });

src/metrics.rs

@@ -274,6 +274,43 @@ async fn render_metrics(stats: &Stats, config: &ProxyConfig, ip_tracker: &UserIp
         }
     );
 
+    let _ = writeln!(out, "# HELP telemt_me_handshake_reject_total ME handshake rejects from upstream");
+    let _ = writeln!(out, "# TYPE telemt_me_handshake_reject_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_handshake_reject_total {}",
+        if me_allows_normal {
+            stats.get_me_handshake_reject_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(out, "# HELP telemt_me_handshake_error_code_total ME handshake reject errors by code");
+    let _ = writeln!(out, "# TYPE telemt_me_handshake_error_code_total counter");
+    if me_allows_normal {
+        for (error_code, count) in stats.get_me_handshake_error_code_counts() {
+            let _ = writeln!(
+                out,
+                "telemt_me_handshake_error_code_total{{error_code=\"{}\"}} {}",
+                error_code,
+                count
+            );
+        }
+    }
+
+    let _ = writeln!(out, "# HELP telemt_me_reader_eof_total ME reader EOF terminations");
+    let _ = writeln!(out, "# TYPE telemt_me_reader_eof_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_reader_eof_total {}",
+        if me_allows_normal {
+            stats.get_me_reader_eof_total()
+        } else {
+            0
+        }
+    );
+
     let _ = writeln!(out, "# HELP telemt_me_crc_mismatch_total ME CRC mismatches");
     let _ = writeln!(out, "# TYPE telemt_me_crc_mismatch_total counter");
     let _ = writeln!(
@@ -385,6 +422,262 @@ async fn render_metrics(stats: &Stats, config: &ProxyConfig, ip_tracker: &UserIp
         }
     );
 
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_endpoint_quarantine_total ME endpoint quarantines due to rapid flaps"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_endpoint_quarantine_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_endpoint_quarantine_total {}",
+        if me_allows_normal {
+            stats.get_me_endpoint_quarantine_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(out, "# HELP telemt_me_kdf_drift_total ME KDF input drift detections");
+    let _ = writeln!(out, "# TYPE telemt_me_kdf_drift_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_kdf_drift_total {}",
+        if me_allows_normal {
+            stats.get_me_kdf_drift_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_kdf_port_only_drift_total ME KDF client-port changes with stable non-port material"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_kdf_port_only_drift_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_kdf_port_only_drift_total {}",
+        if me_allows_debug {
+            stats.get_me_kdf_port_only_drift_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_hardswap_pending_reuse_total Hardswap cycles that reused an existing pending generation"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_hardswap_pending_reuse_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_hardswap_pending_reuse_total {}",
+        if me_allows_debug {
+            stats.get_me_hardswap_pending_reuse_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_hardswap_pending_ttl_expired_total Pending hardswap generations reset by TTL expiration"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_hardswap_pending_ttl_expired_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_hardswap_pending_ttl_expired_total {}",
+        if me_allows_normal {
+            stats.get_me_hardswap_pending_ttl_expired_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_single_endpoint_outage_enter_total Single-endpoint DC outage transitions to active state"
+    );
+    let _ = writeln!(
+        out,
+        "# TYPE telemt_me_single_endpoint_outage_enter_total counter"
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_single_endpoint_outage_enter_total {}",
+        if me_allows_normal {
+            stats.get_me_single_endpoint_outage_enter_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_single_endpoint_outage_exit_total Single-endpoint DC outage recovery transitions"
+    );
+    let _ = writeln!(
+        out,
+        "# TYPE telemt_me_single_endpoint_outage_exit_total counter"
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_single_endpoint_outage_exit_total {}",
+        if me_allows_normal {
+            stats.get_me_single_endpoint_outage_exit_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_single_endpoint_outage_reconnect_attempt_total Reconnect attempts performed during single-endpoint outages"
+    );
+    let _ = writeln!(
+        out,
+        "# TYPE telemt_me_single_endpoint_outage_reconnect_attempt_total counter"
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_single_endpoint_outage_reconnect_attempt_total {}",
+        if me_allows_normal {
+            stats.get_me_single_endpoint_outage_reconnect_attempt_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_single_endpoint_outage_reconnect_success_total Successful reconnect attempts during single-endpoint outages"
+    );
+    let _ = writeln!(
+        out,
+        "# TYPE telemt_me_single_endpoint_outage_reconnect_success_total counter"
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_single_endpoint_outage_reconnect_success_total {}",
+        if me_allows_normal {
+            stats.get_me_single_endpoint_outage_reconnect_success_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_single_endpoint_quarantine_bypass_total Outage reconnect attempts that bypassed quarantine"
+    );
+    let _ = writeln!(
+        out,
+        "# TYPE telemt_me_single_endpoint_quarantine_bypass_total counter"
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_single_endpoint_quarantine_bypass_total {}",
+        if me_allows_normal {
+            stats.get_me_single_endpoint_quarantine_bypass_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_single_endpoint_shadow_rotate_total Successful periodic shadow rotations for single-endpoint DC groups"
+    );
+    let _ = writeln!(
+        out,
+        "# TYPE telemt_me_single_endpoint_shadow_rotate_total counter"
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_single_endpoint_shadow_rotate_total {}",
+        if me_allows_normal {
+            stats.get_me_single_endpoint_shadow_rotate_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_single_endpoint_shadow_rotate_skipped_quarantine_total Shadow rotations skipped because endpoint is quarantined"
+    );
+    let _ = writeln!(
+        out,
+        "# TYPE telemt_me_single_endpoint_shadow_rotate_skipped_quarantine_total counter"
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_single_endpoint_shadow_rotate_skipped_quarantine_total {}",
+        if me_allows_normal {
+            stats.get_me_single_endpoint_shadow_rotate_skipped_quarantine_total()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_floor_mode Runtime ME writer floor policy mode"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_floor_mode gauge");
+    let floor_mode = config.general.me_floor_mode;
+    let _ = writeln!(
+        out,
+        "telemt_me_floor_mode{{mode=\"static\"}} {}",
+        if matches!(floor_mode, crate::config::MeFloorMode::Static) {
+            1
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_floor_mode{{mode=\"adaptive\"}} {}",
+        if matches!(floor_mode, crate::config::MeFloorMode::Adaptive) {
+            1
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_floor_mode_switch_all_total Runtime ME floor mode switches"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_floor_mode_switch_all_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_floor_mode_switch_all_total {}",
+        if me_allows_normal {
+            stats.get_me_floor_mode_switch_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_floor_mode_switch_total{{from=\"static\",to=\"adaptive\"}} {}",
+        if me_allows_normal {
+            stats.get_me_floor_mode_switch_static_to_adaptive_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_floor_mode_switch_total{{from=\"adaptive\",to=\"static\"}} {}",
+        if me_allows_normal {
+            stats.get_me_floor_mode_switch_adaptive_to_static_total()
+        } else {
+            0
+        }
+    );
+
     let _ = writeln!(out, "# HELP telemt_secure_padding_invalid_total Invalid secure frame lengths");
     let _ = writeln!(out, "# TYPE telemt_secure_padding_invalid_total counter");
     let _ = writeln!(
@@ -477,7 +770,7 @@ async fn render_metrics(stats: &Stats, config: &ProxyConfig, ip_tracker: &UserIp
     let _ = writeln!(
         out,
         "telemt_pool_swap_total {}",
-        if me_allows_debug {
+        if me_allows_normal {
             stats.get_pool_swap_total()
         } else {
             0

src/proxy/client.rs

@@ -91,6 +91,11 @@ where
     stats.increment_connects_all();
     let mut real_peer = normalize_ip(peer);
 
+    // For non-TCP streams, use a synthetic local address; may be overridden by PROXY protocol dst
+    let mut local_addr: SocketAddr = format!("0.0.0.0:{}", config.server.port)
+        .parse()
+        .unwrap_or_else(|_| "0.0.0.0:443".parse().unwrap());
+
     if proxy_protocol_enabled {
         match parse_proxy_protocol(&mut stream, peer).await {
             Ok(info) => {
@@ -101,6 +106,9 @@ where
                     "PROXY protocol header parsed"
                 );
                 real_peer = normalize_ip(info.src_addr);
+                if let Some(dst) = info.dst_addr {
+                    local_addr = dst;
+                }
             }
             Err(e) => {
                 stats.increment_connects_bad();
@@ -119,11 +127,6 @@ where
     let beobachten_for_timeout = beobachten.clone();
     let peer_for_timeout = real_peer.ip();
 
-    // For non-TCP streams, use a synthetic local address
-    let local_addr: SocketAddr = format!("0.0.0.0:{}", config.server.port)
-        .parse()
-        .unwrap_or_else(|_| "0.0.0.0:443".parse().unwrap());
-
     // Phase 1: handshake (with timeout)
     let outcome = match timeout(handshake_timeout, async {
         let mut first_bytes = [0u8; 5];
@@ -144,6 +147,7 @@ where
                     writer,
                     &first_bytes,
                     real_peer,
+                    local_addr,
                     &config,
                     &beobachten,
                 )
@@ -169,6 +173,7 @@ where
                         writer,
                         &handshake,
                         real_peer,
+                        local_addr,
                         &config,
                         &beobachten,
                     )
@@ -213,6 +218,7 @@ where
                     writer,
                     &first_bytes,
                     real_peer,
+                    local_addr,
                     &config,
                     &beobachten,
                 )
@@ -238,6 +244,7 @@ where
                         writer,
                         &handshake,
                         real_peer,
+                        local_addr,
                         &config,
                         &beobachten,
                     )
@@ -405,6 +412,8 @@ impl RunningClientHandler {
     }
 
     async fn do_handshake(mut self) -> Result<HandshakeOutcome> {
+        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) => {
@@ -415,6 +424,9 @@ impl RunningClientHandler {
                         "PROXY protocol header parsed"
                     );
                     self.peer = normalize_ip(info.src_addr);
+                    if let Some(dst) = info.dst_addr {
+                        local_addr = dst;
+                    }
                 }
                 Err(e) => {
                     self.stats.increment_connects_bad();
@@ -440,13 +452,13 @@ impl RunningClientHandler {
         debug!(peer = %peer, is_tls = is_tls, "Handshake type detected");
 
         if is_tls {
-            self.handle_tls_client(first_bytes).await
+            self.handle_tls_client(first_bytes, local_addr).await
         } else {
-            self.handle_direct_client(first_bytes).await
+            self.handle_direct_client(first_bytes, local_addr).await
         }
     }
 
-    async fn handle_tls_client(mut self, first_bytes: [u8; 5]) -> Result<HandshakeOutcome> {
+    async fn handle_tls_client(mut self, first_bytes: [u8; 5], local_addr: SocketAddr) -> Result<HandshakeOutcome> {
         let peer = self.peer;
         let _ip_tracker = self.ip_tracker.clone();
 
@@ -463,6 +475,7 @@ impl RunningClientHandler {
                 writer,
                 &first_bytes,
                 peer,
+                local_addr,
                 &self.config,
                 &self.beobachten,
             )
@@ -479,7 +492,6 @@ impl RunningClientHandler {
         let stats = self.stats.clone();
         let buffer_pool = self.buffer_pool.clone();
 
-        let local_addr = self.stream.local_addr().map_err(ProxyError::Io)?;
         let (read_half, write_half) = self.stream.into_split();
 
         let (mut tls_reader, tls_writer, _tls_user) = match handle_tls_handshake(
@@ -502,6 +514,7 @@ impl RunningClientHandler {
                     writer,
                     &handshake,
                     peer,
+                    local_addr,
                     &config,
                     &self.beobachten,
                 )
@@ -558,7 +571,7 @@ impl RunningClientHandler {
         )))
     }
 
-    async fn handle_direct_client(mut self, first_bytes: [u8; 5]) -> Result<HandshakeOutcome> {
+    async fn handle_direct_client(mut self, first_bytes: [u8; 5], local_addr: SocketAddr) -> Result<HandshakeOutcome> {
         let peer = self.peer;
         let _ip_tracker = self.ip_tracker.clone();
 
@@ -571,6 +584,7 @@ impl RunningClientHandler {
                 writer,
                 &first_bytes,
                 peer,
+                local_addr,
                 &self.config,
                 &self.beobachten,
             )
@@ -587,7 +601,6 @@ impl RunningClientHandler {
         let stats = self.stats.clone();
         let buffer_pool = self.buffer_pool.clone();
 
-        let local_addr = self.stream.local_addr().map_err(ProxyError::Io)?;
         let (read_half, write_half) = self.stream.into_split();
 
         let (crypto_reader, crypto_writer, success) = match handle_mtproto_handshake(
@@ -609,6 +622,7 @@ impl RunningClientHandler {
                     writer,
                     &handshake,
                     peer,
+                    local_addr,
                     &config,
                     &self.beobachten,
                 )

src/proxy/masking.rs

@@ -55,6 +55,7 @@ pub async fn handle_bad_client<R, W>(
     writer: W,
     initial_data: &[u8],
     peer: SocketAddr,
+    local_addr: SocketAddr,
     config: &ProxyConfig,
     beobachten: &BeobachtenStore,
 )
@@ -87,7 +88,29 @@ where
         let connect_result = timeout(MASK_TIMEOUT, UnixStream::connect(sock_path)).await;
         match connect_result {
             Ok(Ok(stream)) => {
-                let (mask_read, mask_write) = stream.into_split();
+                let (mask_read, mut mask_write) = stream.into_split();
+                let proxy_header: Option<Vec<u8>> = match config.censorship.mask_proxy_protocol {
+                    0 => None,
+                    version => {
+                        let header = match version {
+                            2 => ProxyProtocolV2Builder::new().with_addrs(peer, local_addr).build(),
+                            _ => match (peer, local_addr) {
+                                (SocketAddr::V4(src), SocketAddr::V4(dst)) =>
+                                    ProxyProtocolV1Builder::new().tcp4(src.into(), dst.into()).build(),
+                                (SocketAddr::V6(src), SocketAddr::V6(dst)) =>
+                                    ProxyProtocolV1Builder::new().tcp6(src.into(), dst.into()).build(),
+                                _ =>
+                                    ProxyProtocolV1Builder::new().build(),
+                            },
+                        };
+                        Some(header)
+                    }
+                };
+                if let Some(header) = proxy_header {
+                    if mask_write.write_all(&header).await.is_err() {
+                        return;
+                    }
+                }
                 if timeout(MASK_RELAY_TIMEOUT, relay_to_mask(reader, writer, mask_read, mask_write, initial_data)).await.is_err() {
                     debug!("Mask relay timed out (unix socket)");
                 }
@@ -126,23 +149,16 @@ where
             let proxy_header: Option<Vec<u8>> = match config.censorship.mask_proxy_protocol {
                 0 => None,
                 version => {
-                    let header = if let Ok(local_addr) = stream.local_addr() {
-                        match version {
-                            2 => ProxyProtocolV2Builder::new().with_addrs(peer, local_addr).build(),
-                            _ => match (peer, local_addr) {
-                                (SocketAddr::V4(src), SocketAddr::V4(dst)) =>
-                                    ProxyProtocolV1Builder::new().tcp4(src.into(), dst.into()).build(),
-                                (SocketAddr::V6(src), SocketAddr::V6(dst)) =>
-                                    ProxyProtocolV1Builder::new().tcp6(src.into(), dst.into()).build(),
-                                _ =>
-                                    ProxyProtocolV1Builder::new().build(),
-                            },
-                        }
-                    } else {
-                        match version {
-                            2 => ProxyProtocolV2Builder::new().build(),
-                            _ => ProxyProtocolV1Builder::new().build(),
-                        }
+                    let header = match version {
+                        2 => ProxyProtocolV2Builder::new().with_addrs(peer, local_addr).build(),
+                        _ => match (peer, local_addr) {
+                            (SocketAddr::V4(src), SocketAddr::V4(dst)) =>
+                                ProxyProtocolV1Builder::new().tcp4(src.into(), dst.into()).build(),
+                            (SocketAddr::V6(src), SocketAddr::V6(dst)) =>
+                                ProxyProtocolV1Builder::new().tcp6(src.into(), dst.into()).build(),
+                            _ =>
+                                ProxyProtocolV1Builder::new().build(),
+                        },
                     };
                     Some(header)
                 }

src/proxy/middle_relay.rs

@@ -26,6 +26,9 @@ enum C2MeCommand {
 
 const DESYNC_DEDUP_WINDOW: Duration = Duration::from_secs(60);
 const DESYNC_ERROR_CLASS: &str = "frame_too_large_crypto_desync";
+const C2ME_CHANNEL_CAPACITY: usize = 1024;
+const C2ME_SOFT_PRESSURE_MIN_FREE_SLOTS: usize = 64;
+const C2ME_SENDER_FAIRNESS_BUDGET: usize = 32;
 static DESYNC_DEDUP: OnceLock<Mutex<HashMap<u64, Instant>>> = OnceLock::new();
 
 struct RelayForensicsState {
@@ -166,6 +169,27 @@ fn report_desync_frame_too_large(
     ))
 }
 
+fn should_yield_c2me_sender(sent_since_yield: usize, has_backlog: bool) -> bool {
+    has_backlog && sent_since_yield >= C2ME_SENDER_FAIRNESS_BUDGET
+}
+
+async fn enqueue_c2me_command(
+    tx: &mpsc::Sender<C2MeCommand>,
+    cmd: C2MeCommand,
+) -> std::result::Result<(), mpsc::error::SendError<C2MeCommand>> {
+    match tx.try_send(cmd) {
+        Ok(()) => Ok(()),
+        Err(mpsc::error::TrySendError::Closed(cmd)) => Err(mpsc::error::SendError(cmd)),
+        Err(mpsc::error::TrySendError::Full(cmd)) => {
+            // Cooperative yield reduces burst catch-up when the per-conn queue is near saturation.
+            if tx.capacity() <= C2ME_SOFT_PRESSURE_MIN_FREE_SLOTS {
+                tokio::task::yield_now().await;
+            }
+            tx.send(cmd).await
+        }
+    }
+}
+
 pub(crate) async fn handle_via_middle_proxy<R, W>(
     mut crypto_reader: CryptoReader<R>,
     crypto_writer: CryptoWriter<W>,
@@ -214,7 +238,22 @@ where
     stats.increment_user_connects(&user);
     stats.increment_user_curr_connects(&user);
 
-    let proto_flags = proto_flags_for_tag(proto_tag, me_pool.has_proxy_tag());
+    // Per-user ad_tag from access.user_ad_tags; fallback to general.ad_tag (hot-reloadable)
+    let user_tag: Option<Vec<u8>> = config
+        .access
+        .user_ad_tags
+        .get(&user)
+        .and_then(|s| hex::decode(s).ok())
+        .filter(|v| v.len() == 16);
+    let global_tag: Option<Vec<u8>> = config
+        .general
+        .ad_tag
+        .as_ref()
+        .and_then(|s| hex::decode(s).ok())
+        .filter(|v| v.len() == 16);
+    let effective_tag = user_tag.or(global_tag);
+
+    let proto_flags = proto_flags_for_tag(proto_tag, effective_tag.is_some());
     debug!(
         trace_id = format_args!("0x{:016x}", trace_id),
         user = %user,
@@ -230,9 +269,11 @@ where
 
     let frame_limit = config.general.max_client_frame;
 
-    let (c2me_tx, mut c2me_rx) = mpsc::channel::<C2MeCommand>(1024);
+    let (c2me_tx, mut c2me_rx) = mpsc::channel::<C2MeCommand>(C2ME_CHANNEL_CAPACITY);
     let me_pool_c2me = me_pool.clone();
+    let effective_tag = effective_tag;
     let c2me_sender = tokio::spawn(async move {
+        let mut sent_since_yield = 0usize;
         while let Some(cmd) = c2me_rx.recv().await {
             match cmd {
                 C2MeCommand::Data { payload, flags } => {
@@ -243,7 +284,13 @@ where
                         translated_local_addr,
                         &payload,
                         flags,
+                        effective_tag.as_deref(),
                     ).await?;
+                    sent_since_yield = sent_since_yield.saturating_add(1);
+                    if should_yield_c2me_sender(sent_since_yield, !c2me_rx.is_empty()) {
+                        sent_since_yield = 0;
+                        tokio::task::yield_now().await;
+                    }
                 }
                 C2MeCommand::Close => {
                     let _ = me_pool_c2me.send_close(conn_id).await;
@@ -360,8 +407,7 @@ where
                     flags |= RPC_FLAG_NOT_ENCRYPTED;
                 }
                 // Keep client read loop lightweight: route heavy ME send path via a dedicated task.
-                if c2me_tx
-                    .send(C2MeCommand::Data { payload, flags })
+                if enqueue_c2me_command(&c2me_tx, C2MeCommand::Data { payload, flags })
                     .await
                     .is_err()
                 {
@@ -372,7 +418,7 @@ where
             Ok(None) => {
                 debug!(conn_id, "Client EOF");
                 client_closed = true;
-                let _ = c2me_tx.send(C2MeCommand::Close).await;
+                let _ = enqueue_c2me_command(&c2me_tx, C2MeCommand::Close).await;
                 break;
             }
             Err(e) => {
@@ -647,3 +693,84 @@ where
     // ACK should remain low-latency.
     client_writer.flush().await.map_err(ProxyError::Io)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tokio::time::{Duration as TokioDuration, timeout};
+
+    #[test]
+    fn should_yield_sender_only_on_budget_with_backlog() {
+        assert!(!should_yield_c2me_sender(0, true));
+        assert!(!should_yield_c2me_sender(C2ME_SENDER_FAIRNESS_BUDGET - 1, true));
+        assert!(!should_yield_c2me_sender(C2ME_SENDER_FAIRNESS_BUDGET, false));
+        assert!(should_yield_c2me_sender(C2ME_SENDER_FAIRNESS_BUDGET, true));
+    }
+
+    #[tokio::test]
+    async fn enqueue_c2me_command_uses_try_send_fast_path() {
+        let (tx, mut rx) = mpsc::channel::<C2MeCommand>(2);
+        enqueue_c2me_command(
+            &tx,
+            C2MeCommand::Data {
+                payload: vec![1, 2, 3],
+                flags: 0,
+            },
+        )
+        .await
+        .unwrap();
+
+        let recv = timeout(TokioDuration::from_millis(50), rx.recv())
+            .await
+            .unwrap()
+            .unwrap();
+        match recv {
+            C2MeCommand::Data { payload, flags } => {
+                assert_eq!(payload, vec![1, 2, 3]);
+                assert_eq!(flags, 0);
+            }
+            C2MeCommand::Close => panic!("unexpected close command"),
+        }
+    }
+
+    #[tokio::test]
+    async fn enqueue_c2me_command_falls_back_to_send_when_queue_is_full() {
+        let (tx, mut rx) = mpsc::channel::<C2MeCommand>(1);
+        tx.send(C2MeCommand::Data {
+            payload: vec![9],
+            flags: 9,
+        })
+        .await
+        .unwrap();
+
+        let tx2 = tx.clone();
+        let producer = tokio::spawn(async move {
+            enqueue_c2me_command(
+                &tx2,
+                C2MeCommand::Data {
+                    payload: vec![7, 7],
+                    flags: 7,
+                },
+            )
+            .await
+            .unwrap();
+        });
+
+        let _ = timeout(TokioDuration::from_millis(100), rx.recv())
+            .await
+            .unwrap();
+        producer.await.unwrap();
+
+        let recv = timeout(TokioDuration::from_millis(100), rx.recv())
+            .await
+            .unwrap()
+            .unwrap();
+        match recv {
+            C2MeCommand::Data { payload, flags } => {
+                assert_eq!(payload, vec![7, 7]);
+                assert_eq!(flags, 7);
+            }
+            C2MeCommand::Close => panic!("unexpected close command"),
+        }
+    }
+}

src/stats/mod.rs

@@ -32,8 +32,26 @@ pub struct Stats {
     me_keepalive_timeout: AtomicU64,
     me_reconnect_attempts: AtomicU64,
     me_reconnect_success: AtomicU64,
+    me_handshake_reject_total: AtomicU64,
+    me_reader_eof_total: AtomicU64,
     me_crc_mismatch: AtomicU64,
     me_seq_mismatch: AtomicU64,
+    me_endpoint_quarantine_total: AtomicU64,
+    me_kdf_drift_total: AtomicU64,
+    me_kdf_port_only_drift_total: AtomicU64,
+    me_hardswap_pending_reuse_total: AtomicU64,
+    me_hardswap_pending_ttl_expired_total: AtomicU64,
+    me_single_endpoint_outage_enter_total: AtomicU64,
+    me_single_endpoint_outage_exit_total: AtomicU64,
+    me_single_endpoint_outage_reconnect_attempt_total: AtomicU64,
+    me_single_endpoint_outage_reconnect_success_total: AtomicU64,
+    me_single_endpoint_quarantine_bypass_total: AtomicU64,
+    me_single_endpoint_shadow_rotate_total: AtomicU64,
+    me_single_endpoint_shadow_rotate_skipped_quarantine_total: AtomicU64,
+    me_floor_mode_switch_total: AtomicU64,
+    me_floor_mode_switch_static_to_adaptive_total: AtomicU64,
+    me_floor_mode_switch_adaptive_to_static_total: AtomicU64,
+    me_handshake_error_codes: DashMap<i32, AtomicU64>,
     me_route_drop_no_conn: AtomicU64,
     me_route_drop_channel_closed: AtomicU64,
     me_route_drop_queue_full: AtomicU64,
@@ -172,6 +190,26 @@ impl Stats {
             self.me_reconnect_success.fetch_add(1, Ordering::Relaxed);
         }
     }
+    pub fn increment_me_handshake_reject_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_handshake_reject_total.fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_handshake_error_code(&self, code: i32) {
+        if !self.telemetry_me_allows_normal() {
+            return;
+        }
+        let entry = self
+            .me_handshake_error_codes
+            .entry(code)
+            .or_insert_with(|| AtomicU64::new(0));
+        entry.fetch_add(1, Ordering::Relaxed);
+    }
+    pub fn increment_me_reader_eof_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_reader_eof_total.fetch_add(1, Ordering::Relaxed);
+        }
+    }
     pub fn increment_me_crc_mismatch(&self) {
         if self.telemetry_me_allows_normal() {
             self.me_crc_mismatch.fetch_add(1, Ordering::Relaxed);
@@ -257,7 +295,7 @@ impl Stats {
         }
     }
     pub fn increment_pool_swap_total(&self) {
-        if self.telemetry_me_allows_debug() {
+        if self.telemetry_me_allows_normal() {
             self.pool_swap_total.fetch_add(1, Ordering::Relaxed);
         }
     }
@@ -333,6 +371,95 @@ impl Stats {
                 .fetch_add(1, Ordering::Relaxed);
         }
     }
+    pub fn increment_me_endpoint_quarantine_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_endpoint_quarantine_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_kdf_drift_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_kdf_drift_total.fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_kdf_port_only_drift_total(&self) {
+        if self.telemetry_me_allows_debug() {
+            self.me_kdf_port_only_drift_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_hardswap_pending_reuse_total(&self) {
+        if self.telemetry_me_allows_debug() {
+            self.me_hardswap_pending_reuse_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_hardswap_pending_ttl_expired_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_hardswap_pending_ttl_expired_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_single_endpoint_outage_enter_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_single_endpoint_outage_enter_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_single_endpoint_outage_exit_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_single_endpoint_outage_exit_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_single_endpoint_outage_reconnect_attempt_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_single_endpoint_outage_reconnect_attempt_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_single_endpoint_outage_reconnect_success_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_single_endpoint_outage_reconnect_success_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_single_endpoint_quarantine_bypass_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_single_endpoint_quarantine_bypass_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_single_endpoint_shadow_rotate_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_single_endpoint_shadow_rotate_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_single_endpoint_shadow_rotate_skipped_quarantine_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_single_endpoint_shadow_rotate_skipped_quarantine_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_floor_mode_switch_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_floor_mode_switch_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_floor_mode_switch_static_to_adaptive_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_floor_mode_switch_static_to_adaptive_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_floor_mode_switch_adaptive_to_static_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_floor_mode_switch_adaptive_to_static_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
     pub fn get_connects_all(&self) -> u64 { self.connects_all.load(Ordering::Relaxed) }
     pub fn get_connects_bad(&self) -> u64 { self.connects_bad.load(Ordering::Relaxed) }
     pub fn get_me_keepalive_sent(&self) -> u64 { self.me_keepalive_sent.load(Ordering::Relaxed) }
@@ -341,8 +468,79 @@ impl Stats {
     pub fn get_me_keepalive_timeout(&self) -> u64 { self.me_keepalive_timeout.load(Ordering::Relaxed) }
     pub fn get_me_reconnect_attempts(&self) -> u64 { self.me_reconnect_attempts.load(Ordering::Relaxed) }
     pub fn get_me_reconnect_success(&self) -> u64 { self.me_reconnect_success.load(Ordering::Relaxed) }
+    pub fn get_me_handshake_reject_total(&self) -> u64 {
+        self.me_handshake_reject_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_reader_eof_total(&self) -> u64 {
+        self.me_reader_eof_total.load(Ordering::Relaxed)
+    }
     pub fn get_me_crc_mismatch(&self) -> u64 { self.me_crc_mismatch.load(Ordering::Relaxed) }
     pub fn get_me_seq_mismatch(&self) -> u64 { self.me_seq_mismatch.load(Ordering::Relaxed) }
+    pub fn get_me_endpoint_quarantine_total(&self) -> u64 {
+        self.me_endpoint_quarantine_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_kdf_drift_total(&self) -> u64 {
+        self.me_kdf_drift_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_kdf_port_only_drift_total(&self) -> u64 {
+        self.me_kdf_port_only_drift_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_hardswap_pending_reuse_total(&self) -> u64 {
+        self.me_hardswap_pending_reuse_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_hardswap_pending_ttl_expired_total(&self) -> u64 {
+        self.me_hardswap_pending_ttl_expired_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_single_endpoint_outage_enter_total(&self) -> u64 {
+        self.me_single_endpoint_outage_enter_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_single_endpoint_outage_exit_total(&self) -> u64 {
+        self.me_single_endpoint_outage_exit_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_single_endpoint_outage_reconnect_attempt_total(&self) -> u64 {
+        self.me_single_endpoint_outage_reconnect_attempt_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_single_endpoint_outage_reconnect_success_total(&self) -> u64 {
+        self.me_single_endpoint_outage_reconnect_success_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_single_endpoint_quarantine_bypass_total(&self) -> u64 {
+        self.me_single_endpoint_quarantine_bypass_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_single_endpoint_shadow_rotate_total(&self) -> u64 {
+        self.me_single_endpoint_shadow_rotate_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_single_endpoint_shadow_rotate_skipped_quarantine_total(&self) -> u64 {
+        self.me_single_endpoint_shadow_rotate_skipped_quarantine_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_floor_mode_switch_total(&self) -> u64 {
+        self.me_floor_mode_switch_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_floor_mode_switch_static_to_adaptive_total(&self) -> u64 {
+        self.me_floor_mode_switch_static_to_adaptive_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_floor_mode_switch_adaptive_to_static_total(&self) -> u64 {
+        self.me_floor_mode_switch_adaptive_to_static_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_handshake_error_code_counts(&self) -> Vec<(i32, u64)> {
+        let mut out: Vec<(i32, u64)> = self
+            .me_handshake_error_codes
+            .iter()
+            .map(|entry| (*entry.key(), entry.value().load(Ordering::Relaxed)))
+            .collect();
+        out.sort_by_key(|(code, _)| *code);
+        out
+    }
     pub fn get_me_route_drop_no_conn(&self) -> u64 { self.me_route_drop_no_conn.load(Ordering::Relaxed) }
     pub fn get_me_route_drop_channel_closed(&self) -> u64 {
         self.me_route_drop_channel_closed.load(Ordering::Relaxed)

src/stream/crypto_stream.rs

@@ -336,22 +336,35 @@ impl PendingCiphertext {
     }
 
     fn remaining_capacity(&self) -> usize {
-        self.max_len.saturating_sub(self.buf.len())
+        self.max_len.saturating_sub(self.pending_len())
+    }
+
+    fn compact_consumed_prefix(&mut self) {
+        if self.pos == 0 {
+            return;
+        }
+
+        if self.pos >= self.buf.len() {
+            self.buf.clear();
+            self.pos = 0;
+            return;
+        }
+
+        let _ = self.buf.split_to(self.pos);
+        self.pos = 0;
     }
 
     fn advance(&mut self, n: usize) {
         self.pos = (self.pos + n).min(self.buf.len());
 
         if self.pos == self.buf.len() {
-            self.buf.clear();
-            self.pos = 0;
+            self.compact_consumed_prefix();
             return;
         }
 
         // Compact when a large prefix was consumed.
         if self.pos >= 16 * 1024 {
-            let _ = self.buf.split_to(self.pos);
-            self.pos = 0;
+            self.compact_consumed_prefix();
         }
     }
 
@@ -379,6 +392,11 @@ impl PendingCiphertext {
             ));
         }
 
+        // Reclaim consumed prefix when physical storage is the only limiter.
+        if self.pos > 0 && self.buf.len() + plaintext.len() > self.max_len {
+            self.compact_consumed_prefix();
+        }
+
         let start = self.buf.len();
         self.buf.reserve(plaintext.len());
         self.buf.extend_from_slice(plaintext);
@@ -777,3 +795,70 @@ impl<S: AsyncWrite + Unpin> AsyncWrite for PassthroughStream<S> {
         Pin::new(&mut self.inner).poll_shutdown(cx)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn test_ctr() -> AesCtr {
+        AesCtr::new(&[0x11; 32], 0x0102_0304_0506_0708_1112_1314_1516_1718)
+    }
+
+    #[test]
+    fn pending_capacity_reclaims_after_partial_advance_without_compaction_threshold() {
+        let mut pending = PendingCiphertext::new(1024);
+        let mut ctr = test_ctr();
+        let payload = vec![0x41; 900];
+        pending.push_encrypted(&mut ctr, &payload).unwrap();
+
+        // Keep position below compaction threshold to validate logical-capacity accounting.
+        pending.advance(800);
+        assert_eq!(pending.pending_len(), 100);
+        assert_eq!(pending.remaining_capacity(), 924);
+    }
+
+    #[test]
+    fn push_encrypted_respects_pending_limit() {
+        let mut pending = PendingCiphertext::new(64);
+        let mut ctr = test_ctr();
+
+        pending.push_encrypted(&mut ctr, &[0x10; 64]).unwrap();
+        let err = pending.push_encrypted(&mut ctr, &[0x20]).unwrap_err();
+        assert_eq!(err.kind(), ErrorKind::WouldBlock);
+    }
+
+    #[test]
+    fn push_encrypted_compacts_prefix_when_physical_buffer_would_overflow() {
+        let mut pending = PendingCiphertext::new(64);
+        let mut ctr = test_ctr();
+
+        pending.push_encrypted(&mut ctr, &[0x22; 60]).unwrap();
+        pending.advance(30);
+        pending.push_encrypted(&mut ctr, &[0x33; 30]).unwrap();
+
+        assert_eq!(pending.pending_len(), 60);
+        assert!(pending.buf.len() <= 64);
+    }
+
+    #[test]
+    fn pending_ciphertext_preserves_stream_order_across_drain_and_append() {
+        let mut pending = PendingCiphertext::new(128);
+        let mut ctr = test_ctr();
+
+        let first = vec![0xA1; 80];
+        let second = vec![0xB2; 40];
+
+        pending.push_encrypted(&mut ctr, &first).unwrap();
+        pending.advance(50);
+        pending.push_encrypted(&mut ctr, &second).unwrap();
+
+        let mut baseline_ctr = test_ctr();
+        let mut baseline_plain = Vec::with_capacity(first.len() + second.len());
+        baseline_plain.extend_from_slice(&first);
+        baseline_plain.extend_from_slice(&second);
+        baseline_ctr.apply(&mut baseline_plain);
+
+        let expected = &baseline_plain[50..];
+        assert_eq!(pending.pending_slice(), expected);
+    }
+}

src/tls_front/fetcher.rs

@@ -499,7 +499,7 @@ async fn fetch_via_raw_tls(
                     sock = %sock_path,
                     "Raw TLS fetch using mask unix socket"
                 );
-                return fetch_via_raw_tls_stream(stream, sni, connect_timeout, 0).await;
+                return fetch_via_raw_tls_stream(stream, sni, connect_timeout, proxy_protocol).await;
             }
             Ok(Err(e)) => {
                 warn!(
@@ -631,7 +631,7 @@ async fn fetch_via_rustls(
                     sock = %sock_path,
                     "Rustls fetch using mask unix socket"
                 );
-                return fetch_via_rustls_stream(stream, host, sni, 0).await;
+                return fetch_via_rustls_stream(stream, host, sni, proxy_protocol).await;
             }
             Ok(Err(e)) => {
                 warn!(

src/transport/middle_proxy/config_updater.rs

@@ -5,15 +5,15 @@ use std::sync::Arc;
 use std::time::Duration;
 
 use httpdate;
-use tokio::sync::watch;
+use tokio::sync::{mpsc, watch};
 use tracing::{debug, info, warn};
 
 use crate::config::ProxyConfig;
 use crate::error::Result;
 
 use super::MePool;
+use super::rotation::{MeReinitTrigger, enqueue_reinit_trigger};
 use super::secret::download_proxy_secret_with_max_len;
-use crate::crypto::SecureRandom;
 use std::time::SystemTime;
 
 async fn retry_fetch(url: &str) -> Option<ProxyConfigData> {
@@ -38,6 +38,8 @@ async fn retry_fetch(url: &str) -> Option<ProxyConfigData> {
 pub struct ProxyConfigData {
     pub map: HashMap<i32, Vec<(IpAddr, u16)>>,
     pub default_dc: Option<i32>,
+    pub http_status: u16,
+    pub proxy_for_lines: u32,
 }
 
 #[derive(Debug, Default)]
@@ -172,6 +174,7 @@ pub async fn fetch_proxy_config(url: &str) -> Result<ProxyConfigData> {
         .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()
@@ -194,9 +197,11 @@ pub async fn fetch_proxy_config(url: &str) -> Result<ProxyConfigData> {
         .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);
         }
     }
 
@@ -214,14 +219,49 @@ pub async fn fetch_proxy_config(url: &str) -> Result<ProxyConfigData> {
             None
         });
 
-    Ok(ProxyConfigData { map, default_dc })
+    Ok(ProxyConfigData {
+        map,
+        default_dc,
+        http_status,
+        proxy_for_lines,
+    })
+}
+
+fn snapshot_passes_guards(
+    cfg: &ProxyConfig,
+    snapshot: &ProxyConfigData,
+    snapshot_name: &'static str,
+) -> bool {
+    if cfg.general.me_snapshot_require_http_2xx
+        && !(200..=299).contains(&snapshot.http_status)
+    {
+        warn!(
+            snapshot = snapshot_name,
+            http_status = snapshot.http_status,
+            "ME snapshot rejected by non-2xx HTTP status"
+        );
+        return false;
+    }
+
+    let min_proxy_for = cfg.general.me_snapshot_min_proxy_for_lines;
+    if snapshot.proxy_for_lines < min_proxy_for {
+        warn!(
+            snapshot = snapshot_name,
+            parsed_proxy_for_lines = snapshot.proxy_for_lines,
+            min_proxy_for_lines = min_proxy_for,
+            "ME snapshot rejected by proxy_for line floor"
+        );
+        return false;
+    }
+
+    true
 }
 
 async fn run_update_cycle(
     pool: &Arc<MePool>,
-    rng: &Arc<SecureRandom>,
     cfg: &ProxyConfig,
     state: &mut UpdaterState,
+    reinit_tx: &mpsc::Sender<MeReinitTrigger>,
 ) {
     pool.update_runtime_reinit_policy(
         cfg.general.hardswap,
@@ -232,6 +272,20 @@ async fn run_update_cycle(
         cfg.general.me_hardswap_warmup_delay_max_ms,
         cfg.general.me_hardswap_warmup_extra_passes,
         cfg.general.me_hardswap_warmup_pass_backoff_base_ms,
+        cfg.general.me_bind_stale_mode,
+        cfg.general.me_bind_stale_ttl_secs,
+        cfg.general.me_secret_atomic_snapshot,
+        cfg.general.me_deterministic_writer_sort,
+        cfg.general.me_single_endpoint_shadow_writers,
+        cfg.general.me_single_endpoint_outage_mode_enabled,
+        cfg.general.me_single_endpoint_outage_disable_quarantine,
+        cfg.general.me_single_endpoint_outage_backoff_min_ms,
+        cfg.general.me_single_endpoint_outage_backoff_max_ms,
+        cfg.general.me_single_endpoint_shadow_rotate_every_secs,
+        cfg.general.me_floor_mode,
+        cfg.general.me_adaptive_floor_idle_secs,
+        cfg.general.me_adaptive_floor_min_writers_single_endpoint,
+        cfg.general.me_adaptive_floor_recover_grace_secs,
     );
 
     let required_cfg_snapshots = cfg.general.me_config_stable_snapshots.max(1);
@@ -242,44 +296,48 @@ async fn run_update_cycle(
     let mut ready_v4: Option<(ProxyConfigData, u64)> = None;
     let cfg_v4 = retry_fetch("https://core.telegram.org/getProxyConfig").await;
     if let Some(cfg_v4) = cfg_v4 {
-        let cfg_v4_hash = hash_proxy_config(&cfg_v4);
-        let stable_hits = state.config_v4.observe(cfg_v4_hash);
-        if stable_hits < required_cfg_snapshots {
-            debug!(
-                stable_hits,
-                required_cfg_snapshots,
-                snapshot = format_args!("0x{cfg_v4_hash:016x}"),
-                "ME config v4 candidate observed"
-            );
-        } else if state.config_v4.is_applied(cfg_v4_hash) {
-            debug!(
-                snapshot = format_args!("0x{cfg_v4_hash:016x}"),
-                "ME config v4 stable snapshot already applied"
-            );
-        } else {
-            ready_v4 = Some((cfg_v4, cfg_v4_hash));
+        if snapshot_passes_guards(cfg, &cfg_v4, "getProxyConfig") {
+            let cfg_v4_hash = hash_proxy_config(&cfg_v4);
+            let stable_hits = state.config_v4.observe(cfg_v4_hash);
+            if stable_hits < required_cfg_snapshots {
+                debug!(
+                    stable_hits,
+                    required_cfg_snapshots,
+                    snapshot = format_args!("0x{cfg_v4_hash:016x}"),
+                    "ME config v4 candidate observed"
+                );
+            } else if state.config_v4.is_applied(cfg_v4_hash) {
+                debug!(
+                    snapshot = format_args!("0x{cfg_v4_hash:016x}"),
+                    "ME config v4 stable snapshot already applied"
+                );
+            } else {
+                ready_v4 = Some((cfg_v4, cfg_v4_hash));
+            }
         }
     }
 
     let mut ready_v6: Option<(ProxyConfigData, u64)> = None;
     let cfg_v6 = retry_fetch("https://core.telegram.org/getProxyConfigV6").await;
     if let Some(cfg_v6) = cfg_v6 {
-        let cfg_v6_hash = hash_proxy_config(&cfg_v6);
-        let stable_hits = state.config_v6.observe(cfg_v6_hash);
-        if stable_hits < required_cfg_snapshots {
-            debug!(
-                stable_hits,
-                required_cfg_snapshots,
-                snapshot = format_args!("0x{cfg_v6_hash:016x}"),
-                "ME config v6 candidate observed"
-            );
-        } else if state.config_v6.is_applied(cfg_v6_hash) {
-            debug!(
-                snapshot = format_args!("0x{cfg_v6_hash:016x}"),
-                "ME config v6 stable snapshot already applied"
-            );
-        } else {
-            ready_v6 = Some((cfg_v6, cfg_v6_hash));
+        if snapshot_passes_guards(cfg, &cfg_v6, "getProxyConfigV6") {
+            let cfg_v6_hash = hash_proxy_config(&cfg_v6);
+            let stable_hits = state.config_v6.observe(cfg_v6_hash);
+            if stable_hits < required_cfg_snapshots {
+                debug!(
+                    stable_hits,
+                    required_cfg_snapshots,
+                    snapshot = format_args!("0x{cfg_v6_hash:016x}"),
+                    "ME config v6 candidate observed"
+                );
+            } else if state.config_v6.is_applied(cfg_v6_hash) {
+                debug!(
+                    snapshot = format_args!("0x{cfg_v6_hash:016x}"),
+                    "ME config v6 stable snapshot already applied"
+                );
+            } else {
+                ready_v6 = Some((cfg_v6, cfg_v6_hash));
+            }
         }
     }
 
@@ -292,28 +350,40 @@ async fn run_update_cycle(
             let update_v6 = ready_v6
                 .as_ref()
                 .map(|(snapshot, _)| snapshot.map.clone());
-
-            let changed = pool.update_proxy_maps(update_v4, update_v6).await;
-
-            if let Some((snapshot, hash)) = ready_v4 {
-                if let Some(dc) = snapshot.default_dc {
-                    pool.default_dc
-                        .store(dc, std::sync::atomic::Ordering::Relaxed);
-                }
-                state.config_v4.mark_applied(hash);
-            }
-
-            if let Some((_snapshot, hash)) = ready_v6 {
-                state.config_v6.mark_applied(hash);
-            }
-
-            state.last_map_apply_at = Some(tokio::time::Instant::now());
-
-            if changed {
-                maps_changed = true;
-                info!("ME config update applied after stable-gate");
+            let update_is_empty =
+                update_v4.is_empty() && update_v6.as_ref().is_none_or(|v| v.is_empty());
+            let apply_outcome = if update_is_empty && !cfg.general.me_snapshot_reject_empty_map {
+                super::pool_config::SnapshotApplyOutcome::AppliedNoDelta
             } else {
-                debug!("ME config stable-gate applied with no map delta");
+                pool.update_proxy_maps(update_v4, update_v6).await
+            };
+
+            if matches!(
+                apply_outcome,
+                super::pool_config::SnapshotApplyOutcome::RejectedEmpty
+            ) {
+                warn!("ME config stable snapshot rejected (empty endpoint map)");
+            } else {
+                if let Some((snapshot, hash)) = ready_v4 {
+                    if let Some(dc) = snapshot.default_dc {
+                        pool.default_dc
+                            .store(dc, std::sync::atomic::Ordering::Relaxed);
+                    }
+                    state.config_v4.mark_applied(hash);
+                }
+
+                if let Some((_snapshot, hash)) = ready_v6 {
+                    state.config_v6.mark_applied(hash);
+                }
+
+                state.last_map_apply_at = Some(tokio::time::Instant::now());
+
+                if apply_outcome.changed() {
+                    maps_changed = true;
+                    info!("ME config update applied after stable-gate");
+                } else {
+                    debug!("ME config stable-gate applied with no map delta");
+                }
             }
         } else if let Some(last) = state.last_map_apply_at {
             let wait_secs = map_apply_cooldown_remaining_secs(last, apply_cooldown);
@@ -325,8 +395,7 @@ async fn run_update_cycle(
     }
 
     if maps_changed {
-        pool.zero_downtime_reinit_after_map_change(rng.as_ref())
-            .await;
+        enqueue_reinit_trigger(reinit_tx, MeReinitTrigger::MapChanged);
     }
 
     pool.reset_stun_state();
@@ -367,8 +436,8 @@ async fn run_update_cycle(
 
 pub async fn me_config_updater(
     pool: Arc<MePool>,
-    rng: Arc<SecureRandom>,
     mut config_rx: watch::Receiver<Arc<ProxyConfig>>,
+    reinit_tx: mpsc::Sender<MeReinitTrigger>,
 ) {
     let mut state = UpdaterState::default();
     let mut update_every_secs = config_rx
@@ -387,7 +456,7 @@ pub async fn me_config_updater(
         tokio::select! {
             _ = &mut sleep => {
                 let cfg = config_rx.borrow().clone();
-                run_update_cycle(&pool, &rng, cfg.as_ref(), &mut state).await;
+                run_update_cycle(&pool, cfg.as_ref(), &mut state, &reinit_tx).await;
                 let refreshed_secs = cfg.general.effective_update_every_secs().max(1);
                 if refreshed_secs != update_every_secs {
                     info!(
@@ -415,6 +484,20 @@ pub async fn me_config_updater(
                     cfg.general.me_hardswap_warmup_delay_max_ms,
                     cfg.general.me_hardswap_warmup_extra_passes,
                     cfg.general.me_hardswap_warmup_pass_backoff_base_ms,
+                    cfg.general.me_bind_stale_mode,
+                    cfg.general.me_bind_stale_ttl_secs,
+                    cfg.general.me_secret_atomic_snapshot,
+                    cfg.general.me_deterministic_writer_sort,
+                    cfg.general.me_single_endpoint_shadow_writers,
+                    cfg.general.me_single_endpoint_outage_mode_enabled,
+                    cfg.general.me_single_endpoint_outage_disable_quarantine,
+                    cfg.general.me_single_endpoint_outage_backoff_min_ms,
+                    cfg.general.me_single_endpoint_outage_backoff_max_ms,
+                    cfg.general.me_single_endpoint_shadow_rotate_every_secs,
+                    cfg.general.me_floor_mode,
+                    cfg.general.me_adaptive_floor_idle_secs,
+                    cfg.general.me_adaptive_floor_min_writers_single_endpoint,
+                    cfg.general.me_adaptive_floor_recover_grace_secs,
                 );
                 let new_secs = cfg.general.effective_update_every_secs().max(1);
                 if new_secs == update_every_secs {
@@ -429,7 +512,7 @@ pub async fn me_config_updater(
                     );
                     update_every_secs = new_secs;
                     update_every = Duration::from_secs(update_every_secs);
-                    run_update_cycle(&pool, &rng, cfg.as_ref(), &mut state).await;
+                    run_update_cycle(&pool, cfg.as_ref(), &mut state, &reinit_tx).await;
                     next_tick = tokio::time::Instant::now() + update_every;
                 } else {
                     info!(

src/transport/middle_proxy/handshake.rs

@@ -1,5 +1,8 @@
 use std::net::{IpAddr, SocketAddr};
+use std::sync::atomic::Ordering;
 use std::time::{Duration, Instant};
+use std::collections::hash_map::DefaultHasher;
+use std::hash::{Hash, Hasher};
 use socket2::{SockRef, TcpKeepalive};
 #[cfg(target_os = "linux")]
 use libc;
@@ -33,6 +36,24 @@ use super::codec::{
 use super::wire::{extract_ip_material, IpMaterial};
 use super::MePool;
 
+const ME_KDF_DRIFT_STRICT: bool = false;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+enum KdfClientPortSource {
+    LocalSocket = 0,
+    SocksBound = 1,
+}
+
+impl KdfClientPortSource {
+    fn from_socks_bound_port(socks_bound_port: Option<u16>) -> Self {
+        if socks_bound_port.is_some() {
+            Self::SocksBound
+        } else {
+            Self::LocalSocket
+        }
+    }
+}
+
 /// Result of a successful ME handshake with timings.
 pub(crate) struct HandshakeOutput {
     pub rd: ReadHalf<TcpStream>,
@@ -46,6 +67,22 @@ pub(crate) struct HandshakeOutput {
 }
 
 impl MePool {
+    fn kdf_material_fingerprint(
+        local_ip_nat: IpAddr,
+        peer_addr_nat: SocketAddr,
+        reflected_ip: Option<IpAddr>,
+        socks_bound_ip: Option<IpAddr>,
+        client_port_source: KdfClientPortSource,
+    ) -> u64 {
+        let mut hasher = DefaultHasher::new();
+        local_ip_nat.hash(&mut hasher);
+        peer_addr_nat.hash(&mut hasher);
+        reflected_ip.hash(&mut hasher);
+        socks_bound_ip.hash(&mut hasher);
+        client_port_source.hash(&mut hasher);
+        hasher.finish()
+    }
+
     async fn resolve_dc_idx_for_endpoint(&self, addr: SocketAddr) -> Option<i16> {
         if addr.is_ipv4() {
             let map = self.proxy_map_v4.read().await;
@@ -267,7 +304,16 @@ impl MePool {
             .unwrap_or_default()
             .as_secs() as u32;
 
-        let ks = self.key_selector().await;
+        let secret_atomic_snapshot = self.secret_atomic_snapshot.load(Ordering::Relaxed);
+        let (ks, secret) = if secret_atomic_snapshot {
+            let snapshot = self.secret_snapshot().await;
+            (snapshot.key_selector, snapshot.secret)
+        } else {
+            // Backward-compatible mode: key selector and secret may come from different updates.
+            let key_selector = self.key_selector().await;
+            let secret = self.secret_snapshot().await.secret;
+            (key_selector, secret)
+        };
         let nonce_payload = build_nonce_payload(ks, crypto_ts, &my_nonce);
         let nonce_frame = build_rpc_frame(-2, &nonce_payload, RpcChecksumMode::Crc32);
         let dump = hex_dump(&nonce_frame[..nonce_frame.len().min(44)]);
@@ -329,10 +375,50 @@ impl MePool {
 
         let ts_bytes = crypto_ts.to_le_bytes();
         let server_port_bytes = peer_addr_nat.port().to_le_bytes();
-        let client_port_for_kdf = socks_bound_addr
+        let socks_bound_port = socks_bound_addr
             .map(|bound| bound.port())
-            .filter(|port| *port != 0)
-            .unwrap_or(local_addr_nat.port());
+            .filter(|port| *port != 0);
+        let client_port_for_kdf = socks_bound_port.unwrap_or(local_addr_nat.port());
+        let client_port_source = KdfClientPortSource::from_socks_bound_port(socks_bound_port);
+        let kdf_fingerprint = Self::kdf_material_fingerprint(
+            local_addr_nat.ip(),
+            peer_addr_nat,
+            reflected.map(|value| value.ip()),
+            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)) =
+            kdf_fingerprint_guard.get(&peer_addr_nat).copied()
+        {
+            if prev_fingerprint != kdf_fingerprint {
+                self.stats.increment_me_kdf_drift_total();
+                warn!(
+                    %peer_addr_nat,
+                    %local_addr_nat,
+                    client_port_for_kdf,
+                    client_port_source = ?client_port_source,
+                    "ME KDF material drift detected for endpoint"
+                );
+                if ME_KDF_DRIFT_STRICT {
+                    return Err(ProxyError::InvalidHandshake(
+                        "ME KDF material drift detected (strict mode)".to_string(),
+                    ));
+                }
+            } else if prev_client_port != client_port_for_kdf {
+                self.stats.increment_me_kdf_port_only_drift_total();
+                debug!(
+                    %peer_addr_nat,
+                    previous_client_port_for_kdf = prev_client_port,
+                    client_port_for_kdf,
+                    client_port_source = ?client_port_source,
+                    "ME KDF client port changed with stable material"
+                );
+            }
+        }
+        kdf_fingerprint_guard.insert(peer_addr_nat, (kdf_fingerprint, client_port_for_kdf));
+        drop(kdf_fingerprint_guard);
+
         let client_port_bytes = client_port_for_kdf.to_le_bytes();
 
         let server_ip = extract_ip_material(peer_addr_nat);
@@ -357,8 +443,6 @@ impl MePool {
 
         let diag_level: u8 = std::env::var("ME_DIAG").ok().and_then(|v| v.parse().ok()).unwrap_or(0);
 
-        let secret: Vec<u8> = self.proxy_secret.read().await.clone();
-
         let prekey_client = build_middleproxy_prekey(
             &srv_nonce,
             &my_nonce,
@@ -532,6 +616,8 @@ impl MePool {
                     } else {
                         -1
                     };
+                    self.stats.increment_me_handshake_reject_total();
+                    self.stats.increment_me_handshake_error_code(err_code);
                     return Err(ProxyError::InvalidHandshake(format!(
                         "ME rejected handshake (error={err_code})"
                     )));

src/transport/middle_proxy/health.rs

@@ -1,11 +1,13 @@
 use std::collections::HashMap;
+use std::collections::HashSet;
 use std::net::SocketAddr;
 use std::sync::Arc;
 use std::time::{Duration, Instant};
 
-use tracing::{debug, info, warn};
 use rand::Rng;
+use tracing::{debug, info, warn};
 
+use crate::config::MeFloorMode;
 use crate::crypto::SecureRandom;
 use crate::network::IpFamily;
 
@@ -15,11 +17,18 @@ const HEALTH_INTERVAL_SECS: u64 = 1;
 const JITTER_FRAC_NUM: u64 = 2; // jitter up to 50% of backoff
 #[allow(dead_code)]
 const MAX_CONCURRENT_PER_DC_DEFAULT: usize = 1;
+const SHADOW_ROTATE_RETRY_SECS: u64 = 30;
 
 pub async fn me_health_monitor(pool: Arc<MePool>, rng: Arc<SecureRandom>, _min_connections: usize) {
     let mut backoff: HashMap<(i32, IpFamily), u64> = HashMap::new();
     let mut next_attempt: HashMap<(i32, IpFamily), Instant> = HashMap::new();
     let mut inflight: HashMap<(i32, IpFamily), usize> = HashMap::new();
+    let mut outage_backoff: HashMap<(i32, IpFamily), u64> = HashMap::new();
+    let mut outage_next_attempt: HashMap<(i32, IpFamily), Instant> = HashMap::new();
+    let mut single_endpoint_outage: HashSet<(i32, IpFamily)> = HashSet::new();
+    let mut shadow_rotate_deadline: HashMap<(i32, IpFamily), Instant> = HashMap::new();
+    let mut adaptive_idle_since: HashMap<(i32, IpFamily), Instant> = HashMap::new();
+    let mut adaptive_recover_until: HashMap<(i32, IpFamily), Instant> = HashMap::new();
     loop {
         tokio::time::sleep(Duration::from_secs(HEALTH_INTERVAL_SECS)).await;
         pool.prune_closed_writers().await;
@@ -30,6 +39,12 @@ pub async fn me_health_monitor(pool: Arc<MePool>, rng: Arc<SecureRandom>, _min_c
             &mut backoff,
             &mut next_attempt,
             &mut inflight,
+            &mut outage_backoff,
+            &mut outage_next_attempt,
+            &mut single_endpoint_outage,
+            &mut shadow_rotate_deadline,
+            &mut adaptive_idle_since,
+            &mut adaptive_recover_until,
         )
         .await;
         check_family(
@@ -39,6 +54,12 @@ pub async fn me_health_monitor(pool: Arc<MePool>, rng: Arc<SecureRandom>, _min_c
             &mut backoff,
             &mut next_attempt,
             &mut inflight,
+            &mut outage_backoff,
+            &mut outage_next_attempt,
+            &mut single_endpoint_outage,
+            &mut shadow_rotate_deadline,
+            &mut adaptive_idle_since,
+            &mut adaptive_recover_until,
         )
         .await;
     }
@@ -51,6 +72,12 @@ async fn check_family(
     backoff: &mut HashMap<(i32, IpFamily), u64>,
     next_attempt: &mut HashMap<(i32, IpFamily), Instant>,
     inflight: &mut HashMap<(i32, IpFamily), usize>,
+    outage_backoff: &mut HashMap<(i32, IpFamily), u64>,
+    outage_next_attempt: &mut HashMap<(i32, IpFamily), Instant>,
+    single_endpoint_outage: &mut HashSet<(i32, IpFamily)>,
+    shadow_rotate_deadline: &mut HashMap<(i32, IpFamily), Instant>,
+    adaptive_idle_since: &mut HashMap<(i32, IpFamily), Instant>,
+    adaptive_recover_until: &mut HashMap<(i32, IpFamily), Instant>,
 ) {
     let enabled = match family {
         IpFamily::V4 => pool.decision.ipv4_me,
@@ -77,32 +104,103 @@ async fn check_family(
         endpoints.dedup();
     }
 
+    if pool.floor_mode() == MeFloorMode::Static {
+        adaptive_idle_since.clear();
+        adaptive_recover_until.clear();
+    }
+
     let mut live_addr_counts = HashMap::<SocketAddr, usize>::new();
-    for writer in pool
-        .writers
-        .read()
-        .await
-        .iter()
-        .filter(|w| !w.draining.load(std::sync::atomic::Ordering::Relaxed))
-    {
+    let mut live_writer_ids_by_addr = HashMap::<SocketAddr, Vec<u64>>::new();
+    for writer in pool.writers.read().await.iter().filter(|w| {
+        !w.draining.load(std::sync::atomic::Ordering::Relaxed)
+    }) {
         *live_addr_counts.entry(writer.addr).or_insert(0) += 1;
+        live_writer_ids_by_addr
+            .entry(writer.addr)
+            .or_default()
+            .push(writer.id);
     }
 
     for (dc, endpoints) in dc_endpoints {
         if endpoints.is_empty() {
             continue;
         }
-        let required = MePool::required_writers_for_dc(endpoints.len());
+        let key = (dc, family);
+        let reduce_for_idle = should_reduce_floor_for_idle(
+            pool,
+            key,
+            &endpoints,
+            &live_writer_ids_by_addr,
+            adaptive_idle_since,
+            adaptive_recover_until,
+        )
+        .await;
+        let required = pool.required_writers_for_dc_with_floor_mode(endpoints.len(), reduce_for_idle);
         let alive = endpoints
             .iter()
             .map(|addr| *live_addr_counts.get(addr).unwrap_or(&0))
             .sum::<usize>();
+
+        if endpoints.len() == 1 && pool.single_endpoint_outage_mode_enabled() && alive == 0 {
+            if single_endpoint_outage.insert(key) {
+                pool.stats.increment_me_single_endpoint_outage_enter_total();
+                warn!(
+                    dc = %dc,
+                    ?family,
+                    required,
+                    endpoint_count = endpoints.len(),
+                    "Single-endpoint DC outage detected"
+                );
+            }
+
+            recover_single_endpoint_outage(
+                pool,
+                rng,
+                key,
+                endpoints[0],
+                required,
+                outage_backoff,
+                outage_next_attempt,
+            )
+            .await;
+            continue;
+        }
+
+        if single_endpoint_outage.remove(&key) {
+            pool.stats.increment_me_single_endpoint_outage_exit_total();
+            outage_backoff.remove(&key);
+            outage_next_attempt.remove(&key);
+            shadow_rotate_deadline.remove(&key);
+            adaptive_idle_since.remove(&key);
+            adaptive_recover_until.remove(&key);
+            info!(
+                dc = %dc,
+                ?family,
+                alive,
+                required,
+                endpoint_count = endpoints.len(),
+                "Single-endpoint DC outage recovered"
+            );
+        }
+
         if alive >= required {
+            maybe_rotate_single_endpoint_shadow(
+                pool,
+                rng,
+                key,
+                dc,
+                family,
+                &endpoints,
+                alive,
+                required,
+                &live_writer_ids_by_addr,
+                shadow_rotate_deadline,
+            )
+            .await;
             continue;
         }
         let missing = required - alive;
 
-        let key = (dc, family);
         let now = Instant::now();
         if let Some(ts) = next_attempt.get(&key)
             && now < *ts
@@ -112,7 +210,18 @@ async fn check_family(
 
         let max_concurrent = pool.me_reconnect_max_concurrent_per_dc.max(1) as usize;
         if *inflight.get(&key).unwrap_or(&0) >= max_concurrent {
-            return;
+            continue;
+        }
+        if pool.has_refill_inflight_for_endpoints(&endpoints).await {
+            debug!(
+                dc = %dc,
+                ?family,
+                alive,
+                required,
+                endpoint_count = endpoints.len(),
+                "Skipping health reconnect: immediate refill is already in flight for this DC group"
+            );
+            continue;
         }
         *inflight.entry(key).or_insert(0) += 1;
 
@@ -177,3 +286,268 @@ async fn check_family(
         }
     }
 }
+
+async fn should_reduce_floor_for_idle(
+    pool: &Arc<MePool>,
+    key: (i32, IpFamily),
+    endpoints: &[SocketAddr],
+    live_writer_ids_by_addr: &HashMap<SocketAddr, Vec<u64>>,
+    adaptive_idle_since: &mut HashMap<(i32, IpFamily), Instant>,
+    adaptive_recover_until: &mut HashMap<(i32, IpFamily), Instant>,
+) -> bool {
+    if endpoints.len() != 1 || pool.floor_mode() != MeFloorMode::Adaptive {
+        adaptive_idle_since.remove(&key);
+        adaptive_recover_until.remove(&key);
+        return false;
+    }
+
+    let now = Instant::now();
+    let endpoint = endpoints[0];
+    let writer_ids = live_writer_ids_by_addr
+        .get(&endpoint)
+        .map(Vec::as_slice)
+        .unwrap_or(&[]);
+    let has_bound_clients = has_bound_clients_on_endpoint(pool, writer_ids).await;
+    if has_bound_clients {
+        adaptive_idle_since.remove(&key);
+        adaptive_recover_until.insert(key, now + pool.adaptive_floor_recover_grace_duration());
+        return false;
+    }
+
+    if let Some(recover_until) = adaptive_recover_until.get(&key)
+        && now < *recover_until
+    {
+        adaptive_idle_since.remove(&key);
+        return false;
+    }
+    adaptive_recover_until.remove(&key);
+
+    let idle_since = adaptive_idle_since.entry(key).or_insert(now);
+    now.saturating_duration_since(*idle_since) >= pool.adaptive_floor_idle_duration()
+}
+
+async fn has_bound_clients_on_endpoint(pool: &Arc<MePool>, writer_ids: &[u64]) -> bool {
+    for writer_id in writer_ids {
+        if !pool.registry.is_writer_empty(*writer_id).await {
+            return true;
+        }
+    }
+    false
+}
+
+async fn recover_single_endpoint_outage(
+    pool: &Arc<MePool>,
+    rng: &Arc<SecureRandom>,
+    key: (i32, IpFamily),
+    endpoint: SocketAddr,
+    required: usize,
+    outage_backoff: &mut HashMap<(i32, IpFamily), u64>,
+    outage_next_attempt: &mut HashMap<(i32, IpFamily), Instant>,
+) {
+    let now = Instant::now();
+    if let Some(ts) = outage_next_attempt.get(&key)
+        && now < *ts
+    {
+        return;
+    }
+
+    let (min_backoff_ms, max_backoff_ms) = pool.single_endpoint_outage_backoff_bounds_ms();
+    pool.stats
+        .increment_me_single_endpoint_outage_reconnect_attempt_total();
+
+    let bypass_quarantine = pool.single_endpoint_outage_disable_quarantine();
+    let attempt_ok = if bypass_quarantine {
+        pool.stats
+            .increment_me_single_endpoint_quarantine_bypass_total();
+        match tokio::time::timeout(pool.me_one_timeout, pool.connect_one(endpoint, rng.as_ref())).await {
+            Ok(Ok(())) => true,
+            Ok(Err(e)) => {
+                debug!(
+                    dc = %key.0,
+                    family = ?key.1,
+                    %endpoint,
+                    error = %e,
+                    "Single-endpoint outage reconnect failed (quarantine bypass path)"
+                );
+                false
+            }
+            Err(_) => {
+                debug!(
+                    dc = %key.0,
+                    family = ?key.1,
+                    %endpoint,
+                    "Single-endpoint outage reconnect timed out (quarantine bypass path)"
+                );
+                false
+            }
+        }
+    } else {
+        let one_endpoint = [endpoint];
+        match tokio::time::timeout(
+            pool.me_one_timeout,
+            pool.connect_endpoints_round_robin(&one_endpoint, rng.as_ref()),
+        )
+        .await
+        {
+            Ok(ok) => ok,
+            Err(_) => {
+                debug!(
+                    dc = %key.0,
+                    family = ?key.1,
+                    %endpoint,
+                    "Single-endpoint outage reconnect timed out"
+                );
+                false
+            }
+        }
+    };
+
+    if attempt_ok {
+        pool.stats
+            .increment_me_single_endpoint_outage_reconnect_success_total();
+        pool.stats.increment_me_reconnect_success();
+        outage_backoff.insert(key, min_backoff_ms);
+        let jitter = min_backoff_ms / JITTER_FRAC_NUM;
+        let wait = Duration::from_millis(min_backoff_ms)
+            + Duration::from_millis(rand::rng().random_range(0..=jitter.max(1)));
+        outage_next_attempt.insert(key, now + wait);
+        info!(
+            dc = %key.0,
+            family = ?key.1,
+            %endpoint,
+            required,
+            backoff_ms = min_backoff_ms,
+            "Single-endpoint outage reconnect succeeded"
+        );
+        return;
+    }
+
+    pool.stats.increment_me_reconnect_attempt();
+    let current_ms = *outage_backoff.get(&key).unwrap_or(&min_backoff_ms);
+    let next_ms = current_ms.saturating_mul(2).min(max_backoff_ms);
+    outage_backoff.insert(key, next_ms);
+    let jitter = next_ms / JITTER_FRAC_NUM;
+    let wait = Duration::from_millis(next_ms)
+        + Duration::from_millis(rand::rng().random_range(0..=jitter.max(1)));
+    outage_next_attempt.insert(key, now + wait);
+    warn!(
+        dc = %key.0,
+        family = ?key.1,
+        %endpoint,
+        required,
+        backoff_ms = next_ms,
+        "Single-endpoint outage reconnect scheduled"
+    );
+}
+
+async fn maybe_rotate_single_endpoint_shadow(
+    pool: &Arc<MePool>,
+    rng: &Arc<SecureRandom>,
+    key: (i32, IpFamily),
+    dc: i32,
+    family: IpFamily,
+    endpoints: &[SocketAddr],
+    alive: usize,
+    required: usize,
+    live_writer_ids_by_addr: &HashMap<SocketAddr, Vec<u64>>,
+    shadow_rotate_deadline: &mut HashMap<(i32, IpFamily), Instant>,
+) {
+    if endpoints.len() != 1 || alive < required {
+        return;
+    }
+
+    let Some(interval) = pool.single_endpoint_shadow_rotate_interval() else {
+        return;
+    };
+
+    let now = Instant::now();
+    if let Some(deadline) = shadow_rotate_deadline.get(&key)
+        && now < *deadline
+    {
+        return;
+    }
+
+    let endpoint = endpoints[0];
+    if pool.is_endpoint_quarantined(endpoint).await {
+        pool.stats
+            .increment_me_single_endpoint_shadow_rotate_skipped_quarantine_total();
+        shadow_rotate_deadline.insert(key, now + Duration::from_secs(SHADOW_ROTATE_RETRY_SECS));
+        debug!(
+            dc = %dc,
+            ?family,
+            %endpoint,
+            "Single-endpoint shadow rotation skipped: endpoint is quarantined"
+        );
+        return;
+    }
+
+    let Some(writer_ids) = live_writer_ids_by_addr.get(&endpoint) else {
+        shadow_rotate_deadline.insert(key, now + Duration::from_secs(SHADOW_ROTATE_RETRY_SECS));
+        return;
+    };
+
+    let mut candidate_writer_id = None;
+    for writer_id in writer_ids {
+        if pool.registry.is_writer_empty(*writer_id).await {
+            candidate_writer_id = Some(*writer_id);
+            break;
+        }
+    }
+
+    let Some(old_writer_id) = candidate_writer_id else {
+        shadow_rotate_deadline.insert(key, now + Duration::from_secs(SHADOW_ROTATE_RETRY_SECS));
+        debug!(
+            dc = %dc,
+            ?family,
+            %endpoint,
+            alive,
+            required,
+            "Single-endpoint shadow rotation skipped: no empty writer candidate"
+        );
+        return;
+    };
+
+    let rotate_ok = match tokio::time::timeout(pool.me_one_timeout, pool.connect_one(endpoint, rng.as_ref())).await {
+        Ok(Ok(())) => true,
+        Ok(Err(e)) => {
+            debug!(
+                dc = %dc,
+                ?family,
+                %endpoint,
+                error = %e,
+                "Single-endpoint shadow rotation connect failed"
+            );
+            false
+        }
+        Err(_) => {
+            debug!(
+                dc = %dc,
+                ?family,
+                %endpoint,
+                "Single-endpoint shadow rotation connect timed out"
+            );
+            false
+        }
+    };
+
+    if !rotate_ok {
+        shadow_rotate_deadline.insert(
+            key,
+            now + interval.min(Duration::from_secs(SHADOW_ROTATE_RETRY_SECS)),
+        );
+        return;
+    }
+
+    pool.mark_writer_draining_with_timeout(old_writer_id, pool.force_close_timeout(), false)
+        .await;
+    pool.stats.increment_me_single_endpoint_shadow_rotate_total();
+    shadow_rotate_deadline.insert(key, now + interval);
+    info!(
+        dc = %dc,
+        ?family,
+        %endpoint,
+        old_writer_id,
+        rotate_every_secs = interval.as_secs(),
+        "Single-endpoint shadow writer rotated"
+    );
+}

src/transport/middle_proxy/mod.rs

@@ -30,7 +30,7 @@ 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};
-pub use rotation::me_rotation_task;
+pub use rotation::{MeReinitTrigger, me_reinit_scheduler, me_rotation_task};
 pub use wire::proto_flags_for_tag;
 
 #[derive(Debug)]

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::MeSocksKdfPolicy;
+use crate::config::{MeBindStaleMode, MeFloorMode, MeSocksKdfPolicy};
 use crate::crypto::SecureRandom;
 use crate::network::IpFamily;
 use crate::network::probe::NetworkDecision;
@@ -16,11 +16,19 @@ use crate::transport::UpstreamManager;
 use super::ConnRegistry;
 use super::codec::WriterCommand;
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub(super) struct RefillDcKey {
+    pub dc: i32,
+    pub family: IpFamily,
+}
+
 #[derive(Clone)]
 pub struct MeWriter {
     pub id: u64,
     pub addr: SocketAddr,
     pub generation: u64,
+    pub contour: Arc<AtomicU8>,
+    pub created_at: Instant,
     pub tx: mpsc::Sender<WriterCommand>,
     pub cancel: CancellationToken,
     pub degraded: Arc<AtomicBool>,
@@ -29,6 +37,36 @@ pub struct MeWriter {
     pub allow_drain_fallback: Arc<AtomicBool>,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(u8)]
+pub(super) enum WriterContour {
+    Warm = 0,
+    Active = 1,
+    Draining = 2,
+}
+
+impl WriterContour {
+    pub(super) fn as_u8(self) -> u8 {
+        self as u8
+    }
+
+    pub(super) fn from_u8(value: u8) -> Self {
+        match value {
+            0 => Self::Warm,
+            1 => Self::Active,
+            2 => Self::Draining,
+            _ => Self::Draining,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct SecretSnapshot {
+    pub epoch: u64,
+    pub key_selector: u32,
+    pub secret: Vec<u8>,
+}
+
 #[allow(dead_code)]
 pub struct MePool {
     pub(super) registry: Arc<ConnRegistry>,
@@ -38,7 +76,7 @@ pub struct MePool {
     pub(super) upstream: Option<Arc<UpstreamManager>>,
     pub(super) rng: Arc<SecureRandom>,
     pub(super) proxy_tag: Option<Vec<u8>>,
-    pub(super) proxy_secret: Arc<RwLock<Vec<u8>>>,
+    pub(super) proxy_secret: Arc<RwLock<SecretSnapshot>>,
     pub(super) nat_ip_cfg: Option<IpAddr>,
     pub(super) nat_ip_detected: Arc<RwLock<Option<IpAddr>>>,
     pub(super) nat_probe: bool,
@@ -63,6 +101,16 @@ pub struct MePool {
     pub(super) me_reconnect_backoff_base: Duration,
     pub(super) me_reconnect_backoff_cap: Duration,
     pub(super) me_reconnect_fast_retry_count: u32,
+    pub(super) me_single_endpoint_shadow_writers: AtomicU8,
+    pub(super) me_single_endpoint_outage_mode_enabled: AtomicBool,
+    pub(super) me_single_endpoint_outage_disable_quarantine: AtomicBool,
+    pub(super) me_single_endpoint_outage_backoff_min_ms: AtomicU64,
+    pub(super) me_single_endpoint_outage_backoff_max_ms: AtomicU64,
+    pub(super) me_single_endpoint_shadow_rotate_every_secs: AtomicU64,
+    pub(super) me_floor_mode: AtomicU8,
+    pub(super) me_adaptive_floor_idle_secs: AtomicU64,
+    pub(super) me_adaptive_floor_min_writers_single_endpoint: AtomicU8,
+    pub(super) me_adaptive_floor_recover_grace_secs: AtomicU64,
     pub(super) proxy_map_v4: Arc<RwLock<HashMap<i32, Vec<(IpAddr, u16)>>>>,
     pub(super) proxy_map_v6: Arc<RwLock<HashMap<i32, Vec<(IpAddr, u16)>>>>,
     pub(super) default_dc: AtomicI32,
@@ -72,10 +120,18 @@ pub struct MePool {
     pub(super) nat_reflection_cache: Arc<Mutex<NatReflectionCache>>,
     pub(super) writer_available: Arc<Notify>,
     pub(super) refill_inflight: Arc<Mutex<HashSet<SocketAddr>>>,
+    pub(super) refill_inflight_dc: Arc<Mutex<HashSet<RefillDcKey>>>,
     pub(super) conn_count: AtomicUsize,
     pub(super) stats: Arc<crate::stats::Stats>,
     pub(super) generation: AtomicU64,
+    pub(super) active_generation: AtomicU64,
+    pub(super) warm_generation: AtomicU64,
+    pub(super) pending_hardswap_generation: AtomicU64,
+    pub(super) pending_hardswap_started_at_epoch_secs: AtomicU64,
+    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) me_pool_drain_ttl_secs: AtomicU64,
     pub(super) me_pool_force_close_secs: AtomicU64,
     pub(super) me_pool_min_fresh_ratio_permille: AtomicU32,
@@ -83,6 +139,10 @@ pub struct MePool {
     pub(super) me_hardswap_warmup_delay_max_ms: AtomicU64,
     pub(super) me_hardswap_warmup_extra_passes: AtomicU32,
     pub(super) me_hardswap_warmup_pass_backoff_base_ms: AtomicU64,
+    pub(super) me_bind_stale_mode: AtomicU8,
+    pub(super) me_bind_stale_ttl_secs: AtomicU64,
+    pub(super) secret_atomic_snapshot: AtomicBool,
+    pub(super) me_deterministic_writer_sort: AtomicBool,
     pub(super) me_socks_kdf_policy: AtomicU8,
     pool_size: usize,
 }
@@ -139,6 +199,16 @@ impl MePool {
         me_reconnect_backoff_base_ms: u64,
         me_reconnect_backoff_cap_ms: u64,
         me_reconnect_fast_retry_count: u32,
+        me_single_endpoint_shadow_writers: u8,
+        me_single_endpoint_outage_mode_enabled: bool,
+        me_single_endpoint_outage_disable_quarantine: bool,
+        me_single_endpoint_outage_backoff_min_ms: u64,
+        me_single_endpoint_outage_backoff_max_ms: u64,
+        me_single_endpoint_shadow_rotate_every_secs: u64,
+        me_floor_mode: MeFloorMode,
+        me_adaptive_floor_idle_secs: u64,
+        me_adaptive_floor_min_writers_single_endpoint: u8,
+        me_adaptive_floor_recover_grace_secs: u64,
         hardswap: bool,
         me_pool_drain_ttl_secs: u64,
         me_pool_force_close_secs: u64,
@@ -147,6 +217,10 @@ impl MePool {
         me_hardswap_warmup_delay_max_ms: u64,
         me_hardswap_warmup_extra_passes: u8,
         me_hardswap_warmup_pass_backoff_base_ms: u64,
+        me_bind_stale_mode: MeBindStaleMode,
+        me_bind_stale_ttl_secs: u64,
+        me_secret_atomic_snapshot: bool,
+        me_deterministic_writer_sort: bool,
         me_socks_kdf_policy: MeSocksKdfPolicy,
         me_route_backpressure_base_timeout_ms: u64,
         me_route_backpressure_high_timeout_ms: u64,
@@ -166,7 +240,20 @@ impl MePool {
             upstream,
             rng,
             proxy_tag,
-            proxy_secret: Arc::new(RwLock::new(proxy_secret)),
+            proxy_secret: Arc::new(RwLock::new(SecretSnapshot {
+                epoch: 1,
+                key_selector: if proxy_secret.len() >= 4 {
+                    u32::from_le_bytes([
+                        proxy_secret[0],
+                        proxy_secret[1],
+                        proxy_secret[2],
+                        proxy_secret[3],
+                    ])
+                } else {
+                    0
+                },
+                secret: proxy_secret,
+            })),
             nat_ip_cfg: nat_ip,
             nat_ip_detected: Arc::new(RwLock::new(None)),
             nat_probe,
@@ -192,6 +279,30 @@ impl MePool {
             me_reconnect_backoff_base: Duration::from_millis(me_reconnect_backoff_base_ms),
             me_reconnect_backoff_cap: Duration::from_millis(me_reconnect_backoff_cap_ms),
             me_reconnect_fast_retry_count,
+            me_single_endpoint_shadow_writers: AtomicU8::new(me_single_endpoint_shadow_writers),
+            me_single_endpoint_outage_mode_enabled: AtomicBool::new(
+                me_single_endpoint_outage_mode_enabled,
+            ),
+            me_single_endpoint_outage_disable_quarantine: AtomicBool::new(
+                me_single_endpoint_outage_disable_quarantine,
+            ),
+            me_single_endpoint_outage_backoff_min_ms: AtomicU64::new(
+                me_single_endpoint_outage_backoff_min_ms,
+            ),
+            me_single_endpoint_outage_backoff_max_ms: AtomicU64::new(
+                me_single_endpoint_outage_backoff_max_ms,
+            ),
+            me_single_endpoint_shadow_rotate_every_secs: AtomicU64::new(
+                me_single_endpoint_shadow_rotate_every_secs,
+            ),
+            me_floor_mode: AtomicU8::new(me_floor_mode.as_u8()),
+            me_adaptive_floor_idle_secs: AtomicU64::new(me_adaptive_floor_idle_secs),
+            me_adaptive_floor_min_writers_single_endpoint: AtomicU8::new(
+                me_adaptive_floor_min_writers_single_endpoint,
+            ),
+            me_adaptive_floor_recover_grace_secs: AtomicU64::new(
+                me_adaptive_floor_recover_grace_secs,
+            ),
             pool_size: 2,
             proxy_map_v4: Arc::new(RwLock::new(proxy_map_v4)),
             proxy_map_v6: Arc::new(RwLock::new(proxy_map_v6)),
@@ -202,9 +313,17 @@ impl MePool {
             nat_reflection_cache: Arc::new(Mutex::new(NatReflectionCache::default())),
             writer_available: Arc::new(Notify::new()),
             refill_inflight: Arc::new(Mutex::new(HashSet::new())),
+            refill_inflight_dc: Arc::new(Mutex::new(HashSet::new())),
             conn_count: AtomicUsize::new(0),
             generation: AtomicU64::new(1),
+            active_generation: AtomicU64::new(1),
+            warm_generation: AtomicU64::new(0),
+            pending_hardswap_generation: AtomicU64::new(0),
+            pending_hardswap_started_at_epoch_secs: AtomicU64::new(0),
+            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())),
             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(
@@ -216,16 +335,16 @@ impl MePool {
             me_hardswap_warmup_pass_backoff_base_ms: AtomicU64::new(
                 me_hardswap_warmup_pass_backoff_base_ms,
             ),
+            me_bind_stale_mode: AtomicU8::new(me_bind_stale_mode.as_u8()),
+            me_bind_stale_ttl_secs: AtomicU64::new(me_bind_stale_ttl_secs),
+            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()),
         })
     }
 
-    pub fn has_proxy_tag(&self) -> bool {
-        self.proxy_tag.is_some()
-    }
-
     pub fn current_generation(&self) -> u64 {
-        self.generation.load(Ordering::Relaxed)
+        self.active_generation.load(Ordering::Relaxed)
     }
 
     pub fn update_runtime_reinit_policy(
@@ -238,6 +357,20 @@ impl MePool {
         hardswap_warmup_delay_max_ms: u64,
         hardswap_warmup_extra_passes: u8,
         hardswap_warmup_pass_backoff_base_ms: u64,
+        bind_stale_mode: MeBindStaleMode,
+        bind_stale_ttl_secs: u64,
+        secret_atomic_snapshot: bool,
+        deterministic_writer_sort: bool,
+        single_endpoint_shadow_writers: u8,
+        single_endpoint_outage_mode_enabled: bool,
+        single_endpoint_outage_disable_quarantine: bool,
+        single_endpoint_outage_backoff_min_ms: u64,
+        single_endpoint_outage_backoff_max_ms: u64,
+        single_endpoint_shadow_rotate_every_secs: u64,
+        floor_mode: MeFloorMode,
+        adaptive_floor_idle_secs: u64,
+        adaptive_floor_min_writers_single_endpoint: u8,
+        adaptive_floor_recover_grace_secs: u64,
     ) {
         self.hardswap.store(hardswap, Ordering::Relaxed);
         self.me_pool_drain_ttl_secs
@@ -254,6 +387,49 @@ impl MePool {
             .store(hardswap_warmup_extra_passes as u32, Ordering::Relaxed);
         self.me_hardswap_warmup_pass_backoff_base_ms
             .store(hardswap_warmup_pass_backoff_base_ms, Ordering::Relaxed);
+        self.me_bind_stale_mode
+            .store(bind_stale_mode.as_u8(), Ordering::Relaxed);
+        self.me_bind_stale_ttl_secs
+            .store(bind_stale_ttl_secs, Ordering::Relaxed);
+        self.secret_atomic_snapshot
+            .store(secret_atomic_snapshot, Ordering::Relaxed);
+        self.me_deterministic_writer_sort
+            .store(deterministic_writer_sort, Ordering::Relaxed);
+        self.me_single_endpoint_shadow_writers
+            .store(single_endpoint_shadow_writers, Ordering::Relaxed);
+        self.me_single_endpoint_outage_mode_enabled
+            .store(single_endpoint_outage_mode_enabled, Ordering::Relaxed);
+        self.me_single_endpoint_outage_disable_quarantine
+            .store(single_endpoint_outage_disable_quarantine, Ordering::Relaxed);
+        self.me_single_endpoint_outage_backoff_min_ms
+            .store(single_endpoint_outage_backoff_min_ms, Ordering::Relaxed);
+        self.me_single_endpoint_outage_backoff_max_ms
+            .store(single_endpoint_outage_backoff_max_ms, Ordering::Relaxed);
+        self.me_single_endpoint_shadow_rotate_every_secs
+            .store(single_endpoint_shadow_rotate_every_secs, Ordering::Relaxed);
+        let previous_floor_mode = self.floor_mode();
+        self.me_floor_mode
+            .store(floor_mode.as_u8(), Ordering::Relaxed);
+        self.me_adaptive_floor_idle_secs
+            .store(adaptive_floor_idle_secs, Ordering::Relaxed);
+        self.me_adaptive_floor_min_writers_single_endpoint
+            .store(adaptive_floor_min_writers_single_endpoint, Ordering::Relaxed);
+        self.me_adaptive_floor_recover_grace_secs
+            .store(adaptive_floor_recover_grace_secs, Ordering::Relaxed);
+        if previous_floor_mode != floor_mode {
+            self.stats.increment_me_floor_mode_switch_total();
+            match (previous_floor_mode, floor_mode) {
+                (MeFloorMode::Static, MeFloorMode::Adaptive) => {
+                    self.stats
+                        .increment_me_floor_mode_switch_static_to_adaptive_total();
+                }
+                (MeFloorMode::Adaptive, MeFloorMode::Static) => {
+                    self.stats
+                        .increment_me_floor_mode_switch_adaptive_to_static_total();
+                }
+                _ => {}
+            }
+        }
     }
 
     pub fn reset_stun_state(&self) {
@@ -307,11 +483,96 @@ impl MePool {
     }
 
     pub(super) async fn key_selector(&self) -> u32 {
-        let secret = self.proxy_secret.read().await;
-        if secret.len() >= 4 {
-            u32::from_le_bytes([secret[0], secret[1], secret[2], secret[3]])
+        self.proxy_secret.read().await.key_selector
+    }
+
+    pub(super) async fn secret_snapshot(&self) -> SecretSnapshot {
+        self.proxy_secret.read().await.clone()
+    }
+
+    pub(super) fn bind_stale_mode(&self) -> MeBindStaleMode {
+        MeBindStaleMode::from_u8(self.me_bind_stale_mode.load(Ordering::Relaxed))
+    }
+
+    pub(super) fn required_writers_for_dc(&self, endpoint_count: usize) -> usize {
+        if endpoint_count == 0 {
+            return 0;
+        }
+        if endpoint_count == 1 {
+            let shadow = self
+                .me_single_endpoint_shadow_writers
+                .load(Ordering::Relaxed) as usize;
+            return (1 + shadow).max(3);
+        }
+        endpoint_count.max(3)
+    }
+
+    pub(super) fn floor_mode(&self) -> MeFloorMode {
+        MeFloorMode::from_u8(self.me_floor_mode.load(Ordering::Relaxed))
+    }
+
+    pub(super) fn adaptive_floor_idle_duration(&self) -> Duration {
+        Duration::from_secs(self.me_adaptive_floor_idle_secs.load(Ordering::Relaxed))
+    }
+
+    pub(super) fn adaptive_floor_recover_grace_duration(&self) -> Duration {
+        Duration::from_secs(
+            self.me_adaptive_floor_recover_grace_secs
+                .load(Ordering::Relaxed),
+        )
+    }
+
+    pub(super) fn required_writers_for_dc_with_floor_mode(
+        &self,
+        endpoint_count: usize,
+        reduce_for_idle: bool,
+    ) -> usize {
+        let base_required = self.required_writers_for_dc(endpoint_count);
+        if !reduce_for_idle {
+            return base_required;
+        }
+        if endpoint_count != 1 || self.floor_mode() != MeFloorMode::Adaptive {
+            return base_required;
+        }
+        let min_writers = (self
+            .me_adaptive_floor_min_writers_single_endpoint
+            .load(Ordering::Relaxed) as usize)
+            .max(1);
+        base_required.min(min_writers)
+    }
+
+    pub(super) fn single_endpoint_outage_mode_enabled(&self) -> bool {
+        self.me_single_endpoint_outage_mode_enabled
+            .load(Ordering::Relaxed)
+    }
+
+    pub(super) fn single_endpoint_outage_disable_quarantine(&self) -> bool {
+        self.me_single_endpoint_outage_disable_quarantine
+            .load(Ordering::Relaxed)
+    }
+
+    pub(super) fn single_endpoint_outage_backoff_bounds_ms(&self) -> (u64, u64) {
+        let min_ms = self
+            .me_single_endpoint_outage_backoff_min_ms
+            .load(Ordering::Relaxed);
+        let max_ms = self
+            .me_single_endpoint_outage_backoff_max_ms
+            .load(Ordering::Relaxed);
+        if min_ms <= max_ms {
+            (min_ms, max_ms)
         } else {
-            0
+            (max_ms, min_ms)
+        }
+    }
+
+    pub(super) fn single_endpoint_shadow_rotate_interval(&self) -> Option<Duration> {
+        let secs = self
+            .me_single_endpoint_shadow_rotate_every_secs
+            .load(Ordering::Relaxed);
+        if secs == 0 {
+            None
+        } else {
+            Some(Duration::from_secs(secs))
         }
     }
 

src/transport/middle_proxy/pool_config.rs

@@ -7,12 +7,29 @@ use tracing::warn;
 
 use super::pool::MePool;
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum SnapshotApplyOutcome {
+    AppliedChanged,
+    AppliedNoDelta,
+    RejectedEmpty,
+}
+
+impl SnapshotApplyOutcome {
+    pub fn changed(self) -> bool {
+        matches!(self, SnapshotApplyOutcome::AppliedChanged)
+    }
+}
+
 impl MePool {
     pub async fn update_proxy_maps(
         &self,
         new_v4: HashMap<i32, Vec<(IpAddr, u16)>>,
         new_v6: Option<HashMap<i32, Vec<(IpAddr, u16)>>>,
-    ) -> bool {
+    ) -> SnapshotApplyOutcome {
+        if new_v4.is_empty() && new_v6.as_ref().is_none_or(|v| v.is_empty()) {
+            return SnapshotApplyOutcome::RejectedEmpty;
+        }
+
         let mut changed = false;
         {
             let mut guard = self.proxy_map_v4.write().await;
@@ -51,7 +68,11 @@ impl MePool {
                 }
             }
         }
-        changed
+        if changed {
+            SnapshotApplyOutcome::AppliedChanged
+        } else {
+            SnapshotApplyOutcome::AppliedNoDelta
+        }
     }
 
     pub async fn update_secret(self: &Arc<Self>, new_secret: Vec<u8>) -> bool {
@@ -60,8 +81,19 @@ impl MePool {
             return false;
         }
         let mut guard = self.proxy_secret.write().await;
-        if *guard != new_secret {
-            *guard = new_secret;
+        if guard.secret != new_secret {
+            guard.secret = new_secret;
+            guard.key_selector = if guard.secret.len() >= 4 {
+                u32::from_le_bytes([
+                    guard.secret[0],
+                    guard.secret[1],
+                    guard.secret[2],
+                    guard.secret[3],
+                ])
+            } else {
+                0
+            };
+            guard.epoch = guard.epoch.saturating_add(1);
             drop(guard);
             self.reconnect_all().await;
             return true;

src/transport/middle_proxy/pool_init.rs

@@ -19,7 +19,7 @@ impl MePool {
             me_servers = self.proxy_map_v4.read().await.len(),
             pool_size,
             key_selector = format_args!("0x{ks:08x}"),
-            secret_len = self.proxy_secret.read().await.len(),
+            secret_len = self.proxy_secret.read().await.secret.len(),
             "Initializing ME pool"
         );
 

src/transport/middle_proxy/pool_refill.rs

@@ -2,27 +2,173 @@ use std::collections::HashSet;
 use std::net::SocketAddr;
 use std::sync::Arc;
 use std::sync::atomic::Ordering;
+use std::time::{Duration, Instant};
 
 use tracing::{debug, info, warn};
 
 use crate::crypto::SecureRandom;
+use crate::network::IpFamily;
 
-use super::pool::MePool;
+use super::pool::{MePool, RefillDcKey, WriterContour};
+
+const ME_FLAP_UPTIME_THRESHOLD_SECS: u64 = 20;
+const ME_FLAP_QUARANTINE_SECS: u64 = 25;
 
 impl MePool {
+    pub(super) async fn maybe_quarantine_flapping_endpoint(
+        &self,
+        addr: SocketAddr,
+        uptime: Duration,
+    ) {
+        if uptime > Duration::from_secs(ME_FLAP_UPTIME_THRESHOLD_SECS) {
+            return;
+        }
+
+        let until = Instant::now() + Duration::from_secs(ME_FLAP_QUARANTINE_SECS);
+        let mut guard = self.endpoint_quarantine.lock().await;
+        guard.retain(|_, expiry| *expiry > Instant::now());
+        guard.insert(addr, until);
+        self.stats.increment_me_endpoint_quarantine_total();
+        warn!(
+            %addr,
+            uptime_ms = uptime.as_millis(),
+            quarantine_secs = ME_FLAP_QUARANTINE_SECS,
+            "ME endpoint temporarily quarantined due to rapid writer flap"
+        );
+    }
+
+    pub(super) async fn is_endpoint_quarantined(&self, addr: SocketAddr) -> bool {
+        let mut guard = self.endpoint_quarantine.lock().await;
+        let now = Instant::now();
+        guard.retain(|_, expiry| *expiry > now);
+        guard.contains_key(&addr)
+    }
+
+    async fn connectable_endpoints(&self, endpoints: &[SocketAddr]) -> Vec<SocketAddr> {
+        if endpoints.is_empty() {
+            return Vec::new();
+        }
+
+        let mut guard = self.endpoint_quarantine.lock().await;
+        let now = Instant::now();
+        guard.retain(|_, expiry| *expiry > now);
+
+        let mut ready = Vec::<SocketAddr>::with_capacity(endpoints.len());
+        let mut earliest_quarantine: Option<(SocketAddr, Instant)> = None;
+        for addr in endpoints {
+            if let Some(expiry) = guard.get(addr).copied() {
+                match earliest_quarantine {
+                    Some((_, current_expiry)) if current_expiry <= expiry => {}
+                    _ => earliest_quarantine = Some((*addr, expiry)),
+                }
+            } else {
+                ready.push(*addr);
+            }
+        }
+
+        if !ready.is_empty() {
+            return ready;
+        }
+
+        if let Some((addr, expiry)) = earliest_quarantine {
+            debug!(
+                %addr,
+                wait_ms = expiry.saturating_duration_since(now).as_millis(),
+                "All ME endpoints are quarantined for the DC group; retrying earliest one"
+            );
+            return vec![addr];
+        }
+
+        Vec::new()
+    }
+
+    pub(super) async fn has_refill_inflight_for_endpoints(&self, endpoints: &[SocketAddr]) -> bool {
+        if endpoints.is_empty() {
+            return false;
+        }
+
+        {
+            let guard = self.refill_inflight.lock().await;
+            if endpoints.iter().any(|addr| guard.contains(addr)) {
+                return true;
+            }
+        }
+
+        let dc_keys = self.resolve_refill_dc_keys_for_endpoints(endpoints).await;
+        if dc_keys.is_empty() {
+            return false;
+        }
+        let guard = self.refill_inflight_dc.lock().await;
+        dc_keys.iter().any(|key| guard.contains(key))
+    }
+
+    async fn resolve_refill_dc_key_for_addr(&self, addr: SocketAddr) -> Option<RefillDcKey> {
+        let family = if addr.is_ipv4() {
+            IpFamily::V4
+        } else {
+            IpFamily::V6
+        };
+        let map = self.proxy_map_for_family(family).await;
+        for (dc, endpoints) in map {
+            if endpoints
+                .into_iter()
+                .any(|(ip, port)| SocketAddr::new(ip, port) == addr)
+            {
+                return Some(RefillDcKey {
+                    dc: dc.abs(),
+                    family,
+                });
+            }
+        }
+        None
+    }
+
+    async fn resolve_refill_dc_keys_for_endpoints(
+        &self,
+        endpoints: &[SocketAddr],
+    ) -> HashSet<RefillDcKey> {
+        let mut out = HashSet::<RefillDcKey>::new();
+        for addr in endpoints {
+            if let Some(key) = self.resolve_refill_dc_key_for_addr(*addr).await {
+                out.insert(key);
+            }
+        }
+        out
+    }
+
     pub(super) async fn connect_endpoints_round_robin(
         self: &Arc<Self>,
         endpoints: &[SocketAddr],
         rng: &SecureRandom,
     ) -> bool {
-        if endpoints.is_empty() {
+        self.connect_endpoints_round_robin_with_generation_contour(
+            endpoints,
+            rng,
+            self.current_generation(),
+            WriterContour::Active,
+        )
+        .await
+    }
+
+    pub(super) async fn connect_endpoints_round_robin_with_generation_contour(
+        self: &Arc<Self>,
+        endpoints: &[SocketAddr],
+        rng: &SecureRandom,
+        generation: u64,
+        contour: WriterContour,
+    ) -> bool {
+        let candidates = self.connectable_endpoints(endpoints).await;
+        if candidates.is_empty() {
             return false;
         }
-        let start = (self.rr.fetch_add(1, Ordering::Relaxed) as usize) % endpoints.len();
-        for offset in 0..endpoints.len() {
-            let idx = (start + offset) % endpoints.len();
-            let addr = endpoints[idx];
-            match self.connect_one(addr, rng).await {
+        let start = (self.rr.fetch_add(1, Ordering::Relaxed) as usize) % candidates.len();
+        for offset in 0..candidates.len() {
+            let idx = (start + offset) % candidates.len();
+            let addr = candidates[idx];
+            match self
+                .connect_one_with_generation_contour(addr, rng, generation, contour)
+                .await
+            {
                 Ok(()) => return true,
                 Err(e) => debug!(%addr, error = %e, "ME connect failed during round-robin warmup"),
             }
@@ -83,29 +229,37 @@ impl MePool {
 
     async fn refill_writer_after_loss(self: &Arc<Self>, addr: SocketAddr) -> bool {
         let fast_retries = self.me_reconnect_fast_retry_count.max(1);
+        let same_endpoint_quarantined = self.is_endpoint_quarantined(addr).await;
 
-        for attempt in 0..fast_retries {
-            self.stats.increment_me_reconnect_attempt();
-            match self.connect_one(addr, self.rng.as_ref()).await {
-                Ok(()) => {
-                    self.stats.increment_me_reconnect_success();
-                    self.stats.increment_me_writer_restored_same_endpoint_total();
-                    info!(
-                        %addr,
-                        attempt = attempt + 1,
-                        "ME writer restored on the same endpoint"
-                    );
-                    return true;
-                }
-                Err(e) => {
-                    debug!(
-                        %addr,
-                        attempt = attempt + 1,
-                        error = %e,
-                        "ME immediate same-endpoint reconnect failed"
-                    );
+        if !same_endpoint_quarantined {
+            for attempt in 0..fast_retries {
+                self.stats.increment_me_reconnect_attempt();
+                match self.connect_one(addr, self.rng.as_ref()).await {
+                    Ok(()) => {
+                        self.stats.increment_me_reconnect_success();
+                        self.stats.increment_me_writer_restored_same_endpoint_total();
+                        info!(
+                            %addr,
+                            attempt = attempt + 1,
+                            "ME writer restored on the same endpoint"
+                        );
+                        return true;
+                    }
+                    Err(e) => {
+                        debug!(
+                            %addr,
+                            attempt = attempt + 1,
+                            error = %e,
+                            "ME immediate same-endpoint reconnect failed"
+                        );
+                    }
                 }
             }
+        } else {
+            debug!(
+                %addr,
+                "Skipping immediate same-endpoint reconnect because endpoint is quarantined"
+            );
         }
 
         let dc_endpoints = self.endpoints_for_same_dc(addr).await;
@@ -138,6 +292,9 @@ impl MePool {
     pub(crate) fn trigger_immediate_refill(self: &Arc<Self>, addr: SocketAddr) {
         let pool = Arc::clone(self);
         tokio::spawn(async move {
+            let dc_endpoints = pool.endpoints_for_same_dc(addr).await;
+            let dc_keys = pool.resolve_refill_dc_keys_for_endpoints(&dc_endpoints).await;
+
             {
                 let mut guard = pool.refill_inflight.lock().await;
                 if !guard.insert(addr) {
@@ -145,6 +302,19 @@ impl MePool {
                     return;
                 }
             }
+
+            if !dc_keys.is_empty() {
+                let mut dc_guard = pool.refill_inflight_dc.lock().await;
+                if dc_keys.iter().any(|key| dc_guard.contains(key)) {
+                    pool.stats.increment_me_refill_skipped_inflight_total();
+                    drop(dc_guard);
+                    let mut guard = pool.refill_inflight.lock().await;
+                    guard.remove(&addr);
+                    return;
+                }
+                dc_guard.extend(dc_keys.iter().copied());
+            }
+
             pool.stats.increment_me_refill_triggered_total();
 
             let restored = pool.refill_writer_after_loss(addr).await;
@@ -154,6 +324,13 @@ impl MePool {
 
             let mut guard = pool.refill_inflight.lock().await;
             guard.remove(&addr);
+            drop(guard);
+            if !dc_keys.is_empty() {
+                let mut dc_guard = pool.refill_inflight_dc.lock().await;
+                for key in &dc_keys {
+                    dc_guard.remove(key);
+                }
+            }
         });
     }
 }

src/transport/middle_proxy/pool_reinit.rs

@@ -1,4 +1,5 @@
 use std::collections::{HashMap, HashSet};
+use std::hash::{Hash, Hasher};
 use std::net::SocketAddr;
 use std::sync::Arc;
 use std::sync::atomic::Ordering;
@@ -7,12 +8,58 @@ use std::time::Duration;
 use rand::Rng;
 use rand::seq::SliceRandom;
 use tracing::{debug, info, warn};
+use std::collections::hash_map::DefaultHasher;
 
 use crate::crypto::SecureRandom;
 
-use super::pool::MePool;
+use super::pool::{MePool, WriterContour};
+
+const ME_HARDSWAP_PENDING_TTL_SECS: u64 = 1800;
 
 impl MePool {
+    fn desired_map_hash(desired_by_dc: &HashMap<i32, HashSet<SocketAddr>>) -> u64 {
+        let mut hasher = DefaultHasher::new();
+        let mut dcs: Vec<i32> = desired_by_dc.keys().copied().collect();
+        dcs.sort_unstable();
+        for dc in dcs {
+            dc.hash(&mut hasher);
+            let mut endpoints: Vec<SocketAddr> = desired_by_dc
+                .get(&dc)
+                .map(|set| set.iter().copied().collect())
+                .unwrap_or_default();
+            endpoints.sort_unstable();
+            for endpoint in endpoints {
+                endpoint.hash(&mut hasher);
+            }
+        }
+        hasher.finish()
+    }
+
+    fn clear_pending_hardswap_state(&self) {
+        self.pending_hardswap_generation.store(0, Ordering::Relaxed);
+        self.pending_hardswap_started_at_epoch_secs
+            .store(0, Ordering::Relaxed);
+        self.pending_hardswap_map_hash.store(0, Ordering::Relaxed);
+        self.warm_generation.store(0, Ordering::Relaxed);
+    }
+
+    async fn promote_warm_generation_to_active(&self, generation: u64) {
+        self.active_generation.store(generation, Ordering::Relaxed);
+        self.warm_generation.store(0, Ordering::Relaxed);
+
+        let ws = self.writers.read().await;
+        for writer in ws.iter() {
+            if writer.draining.load(Ordering::Relaxed) {
+                continue;
+            }
+            if writer.generation == generation {
+                writer
+                    .contour
+                    .store(WriterContour::Active.as_u8(), Ordering::Relaxed);
+            }
+        }
+    }
+
     fn coverage_ratio(
         desired_by_dc: &HashMap<i32, HashSet<SocketAddr>>,
         active_writer_addrs: &HashSet<SocketAddr>,
@@ -101,10 +148,6 @@ impl MePool {
         out
     }
 
-    pub(super) fn required_writers_for_dc(endpoint_count: usize) -> usize {
-        endpoint_count.max(3)
-    }
-
     fn hardswap_warmup_connect_delay_ms(&self) -> u64 {
         let min_ms = self.me_hardswap_warmup_delay_min_ms.load(Ordering::Relaxed);
         let max_ms = self.me_hardswap_warmup_delay_max_ms.load(Ordering::Relaxed);
@@ -174,7 +217,7 @@ impl MePool {
 
             let mut endpoint_list: Vec<SocketAddr> = endpoints.iter().copied().collect();
             endpoint_list.sort_unstable();
-            let required = Self::required_writers_for_dc(endpoint_list.len());
+            let required = self.required_writers_for_dc(endpoint_list.len());
             let mut completed = false;
             let mut last_fresh_count = self
                 .fresh_writer_count_for_endpoints(generation, endpoints)
@@ -202,7 +245,14 @@ impl MePool {
                     let delay_ms = self.hardswap_warmup_connect_delay_ms();
                     tokio::time::sleep(Duration::from_millis(delay_ms)).await;
 
-                    let connected = self.connect_endpoints_round_robin(&endpoint_list, rng).await;
+                    let connected = self
+                        .connect_endpoints_round_robin_with_generation_contour(
+                            &endpoint_list,
+                            rng,
+                            generation,
+                            WriterContour::Warm,
+                        )
+                        .await;
                     debug!(
                         dc = *dc,
                         pass = pass_idx + 1,
@@ -265,11 +315,61 @@ impl MePool {
             return;
         }
 
+        let desired_map_hash = Self::desired_map_hash(&desired_by_dc);
+        let now_epoch_secs = Self::now_epoch_secs();
         let previous_generation = self.current_generation();
-        let generation = self.generation.fetch_add(1, Ordering::Relaxed) + 1;
         let hardswap = self.hardswap.load(Ordering::Relaxed);
+        let generation = if hardswap {
+            let pending_generation = self.pending_hardswap_generation.load(Ordering::Relaxed);
+            let pending_started_at = self
+                .pending_hardswap_started_at_epoch_secs
+                .load(Ordering::Relaxed);
+            let pending_map_hash = self.pending_hardswap_map_hash.load(Ordering::Relaxed);
+            let pending_age_secs = now_epoch_secs.saturating_sub(pending_started_at);
+            let pending_ttl_expired = pending_started_at > 0 && pending_age_secs > ME_HARDSWAP_PENDING_TTL_SECS;
+            let pending_matches_map = pending_map_hash != 0 && pending_map_hash == desired_map_hash;
+
+            if pending_generation != 0
+                && pending_generation >= previous_generation
+                && pending_matches_map
+                && !pending_ttl_expired
+            {
+                self.stats.increment_me_hardswap_pending_reuse_total();
+                debug!(
+                    previous_generation,
+                    generation = pending_generation,
+                    pending_age_secs,
+                    "ME hardswap continues with pending generation"
+                );
+                pending_generation
+            } else {
+                if pending_generation != 0 && pending_ttl_expired {
+                    self.stats.increment_me_hardswap_pending_ttl_expired_total();
+                    warn!(
+                        previous_generation,
+                        generation = pending_generation,
+                        pending_age_secs,
+                        pending_ttl_secs = ME_HARDSWAP_PENDING_TTL_SECS,
+                        "ME hardswap pending generation expired by TTL; starting fresh generation"
+                    );
+                }
+                let next_generation = self.generation.fetch_add(1, Ordering::Relaxed) + 1;
+                self.pending_hardswap_generation
+                    .store(next_generation, Ordering::Relaxed);
+                self.pending_hardswap_started_at_epoch_secs
+                    .store(now_epoch_secs, Ordering::Relaxed);
+                self.pending_hardswap_map_hash
+                    .store(desired_map_hash, Ordering::Relaxed);
+                self.warm_generation.store(next_generation, Ordering::Relaxed);
+                next_generation
+            }
+        } else {
+            self.clear_pending_hardswap_state();
+            self.generation.fetch_add(1, Ordering::Relaxed) + 1
+        };
 
         if hardswap {
+            self.warm_generation.store(generation, Ordering::Relaxed);
             self.warmup_generation_for_all_dcs(rng, generation, &desired_by_dc)
                 .await;
         } else {
@@ -305,7 +405,7 @@ impl MePool {
                 if endpoints.is_empty() {
                     continue;
                 }
-                let required = Self::required_writers_for_dc(endpoints.len());
+                let required = self.required_writers_for_dc(endpoints.len());
                 let fresh_count = writers
                     .iter()
                     .filter(|w| !w.draining.load(Ordering::Relaxed))
@@ -334,6 +434,10 @@ impl MePool {
             return;
         }
 
+        if hardswap {
+            self.promote_warm_generation_to_active(generation).await;
+        }
+
         let desired_addrs: HashSet<SocketAddr> = desired_by_dc
             .values()
             .flat_map(|set| set.iter().copied())
@@ -354,6 +458,9 @@ impl MePool {
         drop(writers);
 
         if stale_writer_ids.is_empty() {
+            if hardswap {
+                self.clear_pending_hardswap_state();
+            }
             debug!("ME reinit cycle completed with no stale writers");
             return;
         }
@@ -375,6 +482,9 @@ impl MePool {
             self.mark_writer_draining_with_timeout(writer_id, drain_timeout, !hardswap)
                 .await;
         }
+        if hardswap {
+            self.clear_pending_hardswap_state();
+        }
     }
 
     pub async fn zero_downtime_reinit_periodic(self: &Arc<Self>, rng: &SecureRandom) {

src/transport/middle_proxy/pool_writer.rs

@@ -1,6 +1,6 @@
 use std::net::SocketAddr;
 use std::sync::Arc;
-use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicU8, AtomicU64, Ordering};
 use std::time::{Duration, Instant};
 
 use bytes::BytesMut;
@@ -9,12 +9,13 @@ use tokio::sync::mpsc;
 use tokio_util::sync::CancellationToken;
 use tracing::{debug, info, warn};
 
+use crate::config::MeBindStaleMode;
 use crate::crypto::SecureRandom;
 use crate::error::{ProxyError, Result};
 use crate::protocol::constants::RPC_PING_U32;
 
 use super::codec::{RpcWriter, WriterCommand};
-use super::pool::{MePool, MeWriter};
+use super::pool::{MePool, MeWriter, WriterContour};
 use super::reader::reader_loop;
 use super::registry::BoundConn;
 
@@ -42,7 +43,23 @@ impl MePool {
     }
 
     pub(crate) async fn connect_one(self: &Arc<Self>, addr: SocketAddr, rng: &SecureRandom) -> Result<()> {
-        let secret_len = self.proxy_secret.read().await.len();
+        self.connect_one_with_generation_contour(
+            addr,
+            rng,
+            self.current_generation(),
+            WriterContour::Active,
+        )
+        .await
+    }
+
+    pub(super) async fn connect_one_with_generation_contour(
+        self: &Arc<Self>,
+        addr: SocketAddr,
+        rng: &SecureRandom,
+        generation: u64,
+        contour: WriterContour,
+    ) -> Result<()> {
+        let secret_len = self.proxy_secret.read().await.secret.len();
         if secret_len < 32 {
             return Err(ProxyError::Proxy("proxy-secret too short for ME auth".into()));
         }
@@ -51,7 +68,7 @@ impl MePool {
         let hs = self.handshake_only(stream, addr, upstream_egress, rng).await?;
 
         let writer_id = self.next_writer_id.fetch_add(1, Ordering::Relaxed);
-        let generation = self.current_generation();
+        let contour = Arc::new(AtomicU8::new(contour.as_u8()));
         let cancel = CancellationToken::new();
         let degraded = Arc::new(AtomicBool::new(false));
         let draining = Arc::new(AtomicBool::new(false));
@@ -88,6 +105,8 @@ impl MePool {
             id: writer_id,
             addr,
             generation,
+            contour: contour.clone(),
+            created_at: Instant::now(),
             tx: tx.clone(),
             cancel: cancel.clone(),
             degraded: degraded.clone(),
@@ -248,6 +267,7 @@ impl MePool {
     async fn remove_writer_only(self: &Arc<Self>, writer_id: u64) -> Vec<BoundConn> {
         let mut close_tx: Option<mpsc::Sender<WriterCommand>> = None;
         let mut removed_addr: Option<SocketAddr> = None;
+        let mut removed_uptime: Option<Duration> = None;
         let mut trigger_refill = false;
         {
             let mut ws = self.writers.write().await;
@@ -260,6 +280,7 @@ impl MePool {
                 self.stats.increment_me_writer_removed_total();
                 w.cancel.cancel();
                 removed_addr = Some(w.addr);
+                removed_uptime = Some(w.created_at.elapsed());
                 trigger_refill = !was_draining;
                 if trigger_refill {
                     self.stats.increment_me_writer_removed_unexpected_total();
@@ -274,6 +295,9 @@ impl MePool {
         if trigger_refill
             && let Some(addr) = removed_addr
         {
+            if let Some(uptime) = removed_uptime {
+                self.maybe_quarantine_flapping_endpoint(addr, uptime).await;
+            }
             self.trigger_immediate_refill(addr);
         }
         self.rtt_stats.lock().await.remove(&writer_id);
@@ -298,6 +322,8 @@ impl MePool {
                 if !already_draining {
                     self.stats.increment_pool_drain_active();
                 }
+                w.contour
+                    .store(WriterContour::Draining.as_u8(), Ordering::Relaxed);
                 w.draining.store(true, Ordering::Relaxed);
                 true
             } else {
@@ -351,16 +377,22 @@ impl MePool {
             return false;
         }
 
-        let ttl_secs = self.me_pool_drain_ttl_secs.load(Ordering::Relaxed);
-        if ttl_secs == 0 {
-            return true;
-        }
+        match self.bind_stale_mode() {
+            MeBindStaleMode::Never => false,
+            MeBindStaleMode::Always => true,
+            MeBindStaleMode::Ttl => {
+                let ttl_secs = self.me_bind_stale_ttl_secs.load(Ordering::Relaxed);
+                if ttl_secs == 0 {
+                    return true;
+                }
 
-        let started = writer.draining_started_at_epoch_secs.load(Ordering::Relaxed);
-        if started == 0 {
-            return false;
-        }
+                let started = writer.draining_started_at_epoch_secs.load(Ordering::Relaxed);
+                if started == 0 {
+                    return false;
+                }
 
-        Self::now_epoch_secs().saturating_sub(started) <= ttl_secs
+                Self::now_epoch_secs().saturating_sub(started) <= ttl_secs
+            }
+        }
     }
 }

src/transport/middle_proxy/reader.rs

@@ -1,4 +1,5 @@
 use std::collections::HashMap;
+use std::io::ErrorKind;
 use std::sync::Arc;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::time::Instant;
@@ -45,7 +46,11 @@ pub(crate) async fn reader_loop(
             _ = cancel.cancelled() => return Ok(()),
         };
         if n == 0 {
-            return Ok(());
+            stats.increment_me_reader_eof_total();
+            return Err(ProxyError::Io(std::io::Error::new(
+                ErrorKind::UnexpectedEof,
+                "ME socket closed by peer",
+            )));
         }
         raw.extend_from_slice(&tmp[..n]);
 

src/transport/middle_proxy/rotation.rs

@@ -1,19 +1,111 @@
 use std::sync::Arc;
 use std::time::Duration;
 
-use tokio::sync::watch;
-use tracing::{info, warn};
+use tokio::sync::{mpsc, watch};
+use tracing::{debug, info, warn};
 
 use crate::config::ProxyConfig;
 use crate::crypto::SecureRandom;
 
 use super::MePool;
 
-/// Periodically reinitialize ME generations and swap them after full warmup.
-pub async fn me_rotation_task(
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum MeReinitTrigger {
+    Periodic,
+    MapChanged,
+}
+
+impl MeReinitTrigger {
+    fn as_str(self) -> &'static str {
+        match self {
+            MeReinitTrigger::Periodic => "periodic",
+            MeReinitTrigger::MapChanged => "map-change",
+        }
+    }
+}
+
+pub fn enqueue_reinit_trigger(
+    tx: &mpsc::Sender<MeReinitTrigger>,
+    trigger: MeReinitTrigger,
+) {
+    match tx.try_send(trigger) {
+        Ok(()) => {}
+        Err(tokio::sync::mpsc::error::TrySendError::Full(_)) => {
+            debug!(trigger = trigger.as_str(), "ME reinit trigger dropped (queue full)");
+        }
+        Err(tokio::sync::mpsc::error::TrySendError::Closed(_)) => {
+            warn!(trigger = trigger.as_str(), "ME reinit trigger dropped (scheduler closed)");
+        }
+    }
+}
+
+pub async fn me_reinit_scheduler(
     pool: Arc<MePool>,
     rng: Arc<SecureRandom>,
+    config_rx: watch::Receiver<Arc<ProxyConfig>>,
+    mut trigger_rx: mpsc::Receiver<MeReinitTrigger>,
+) {
+    info!("ME reinit scheduler started");
+    loop {
+        let Some(first_trigger) = trigger_rx.recv().await else {
+            warn!("ME reinit scheduler stopped: trigger channel closed");
+            break;
+        };
+
+        let mut map_change_seen = matches!(first_trigger, MeReinitTrigger::MapChanged);
+        let mut periodic_seen = matches!(first_trigger, MeReinitTrigger::Periodic);
+        let cfg = config_rx.borrow().clone();
+        let coalesce_window = Duration::from_millis(cfg.general.me_reinit_coalesce_window_ms);
+        if !coalesce_window.is_zero() {
+            let deadline = tokio::time::Instant::now() + coalesce_window;
+            loop {
+                let now = tokio::time::Instant::now();
+                if now >= deadline {
+                    break;
+                }
+                match tokio::time::timeout(deadline - now, trigger_rx.recv()).await {
+                    Ok(Some(next)) => {
+                        if next == MeReinitTrigger::MapChanged {
+                            map_change_seen = true;
+                        } else {
+                            periodic_seen = true;
+                        }
+                    }
+                    Ok(None) => break,
+                    Err(_) => break,
+                }
+            }
+        }
+
+        let reason = if map_change_seen && periodic_seen {
+            "map-change+periodic"
+        } else if map_change_seen {
+            "map-change"
+        } else {
+            "periodic"
+        };
+
+        if cfg.general.me_reinit_singleflight {
+            debug!(reason, "ME reinit scheduled (single-flight)");
+            pool.zero_downtime_reinit_periodic(rng.as_ref()).await;
+        } else {
+            debug!(reason, "ME reinit scheduled (concurrent mode)");
+            let pool_clone = pool.clone();
+            let rng_clone = rng.clone();
+            tokio::spawn(async move {
+                pool_clone
+                    .zero_downtime_reinit_periodic(rng_clone.as_ref())
+                    .await;
+            });
+        }
+
+    }
+}
+
+/// Periodically enqueue reinitialization triggers for ME generations.
+pub async fn me_rotation_task(
     mut config_rx: watch::Receiver<Arc<ProxyConfig>>,
+    reinit_tx: mpsc::Sender<MeReinitTrigger>,
 ) {
     let mut interval_secs = config_rx
         .borrow()
@@ -31,7 +123,7 @@ pub async fn me_rotation_task(
 
         tokio::select! {
             _ = &mut sleep => {
-                pool.zero_downtime_reinit_periodic(rng.as_ref()).await;
+                enqueue_reinit_trigger(&reinit_tx, MeReinitTrigger::Periodic);
                 let refreshed_secs = config_rx
                     .borrow()
                     .general
@@ -70,7 +162,7 @@ pub async fn me_rotation_task(
                     );
                     interval_secs = new_secs;
                     interval = Duration::from_secs(interval_secs);
-                    pool.zero_downtime_reinit_periodic(rng.as_ref()).await;
+                    enqueue_reinit_trigger(&reinit_tx, MeReinitTrigger::Periodic);
                     next_tick = tokio::time::Instant::now() + interval;
                 } else {
                     info!(

src/transport/middle_proxy/send.rs

@@ -1,8 +1,10 @@
+use std::cmp::Reverse;
 use std::net::SocketAddr;
 use std::sync::Arc;
 use std::sync::atomic::Ordering;
 use std::time::Duration;
 
+use tokio::sync::mpsc::error::TrySendError;
 use tracing::{debug, warn};
 
 use crate::error::{ProxyError, Result};
@@ -11,11 +13,13 @@ use crate::protocol::constants::RPC_CLOSE_EXT_U32;
 
 use super::MePool;
 use super::codec::WriterCommand;
+use super::pool::WriterContour;
 use super::wire::build_proxy_req_payload;
 use rand::seq::SliceRandom;
 use super::registry::ConnMeta;
 
 impl MePool {
+    /// Send RPC_PROXY_REQ. `tag_override`: per-user ad_tag (from access.user_ad_tags); if None, uses pool default.
     pub async fn send_proxy_req(
         self: &Arc<Self>,
         conn_id: u64,
@@ -24,13 +28,15 @@ impl MePool {
         our_addr: SocketAddr,
         data: &[u8],
         proto_flags: u32,
+        tag_override: Option<&[u8]>,
     ) -> Result<()> {
+        let tag = tag_override.or(self.proxy_tag.as_deref());
         let payload = build_proxy_req_payload(
             conn_id,
             client_addr,
             our_addr,
             data,
-            self.proxy_tag.as_deref(),
+            tag,
             proto_flags,
         );
         let meta = ConnMeta {
@@ -43,15 +49,17 @@ impl MePool {
 
         loop {
             if let Some(current) = self.registry.get_writer(conn_id).await {
-                let send_res = {
-                    current
-                        .tx
-                        .send(WriterCommand::Data(payload.clone()))
-                        .await
-                };
-                match send_res {
+                match current.tx.try_send(WriterCommand::Data(payload.clone())) {
                     Ok(()) => return Ok(()),
-                    Err(_) => {
+                    Err(TrySendError::Full(cmd)) => {
+                        if current.tx.send(cmd).await.is_ok() {
+                            return Ok(());
+                        }
+                        warn!(writer_id = current.writer_id, "ME writer channel closed");
+                        self.remove_writer_and_close_clients(current.writer_id).await;
+                        continue;
+                    }
+                    Err(TrySendError::Closed(_)) => {
                         warn!(writer_id = current.writer_id, "ME writer channel closed");
                         self.remove_writer_and_close_clients(current.writer_id).await;
                         continue;
@@ -94,7 +102,14 @@ impl MePool {
                 ws.clone()
             };
 
-            let mut candidate_indices = self.candidate_indices_for_dc(&writers_snapshot, target_dc).await;
+            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;
+            }
             if candidate_indices.is_empty() {
                 // Emergency connect-on-demand
                 if emergency_attempts >= 3 {
@@ -120,7 +135,14 @@ impl MePool {
                         let ws2 = self.writers.read().await;
                         writers_snapshot = ws2.clone();
                         drop(ws2);
-                        candidate_indices = self.candidate_indices_for_dc(&writers_snapshot, target_dc).await;
+                        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;
                         }
@@ -131,14 +153,44 @@ impl MePool {
                 }
             }
 
-            candidate_indices.sort_by_key(|idx| {
-                let w = &writers_snapshot[*idx];
-                let degraded = w.degraded.load(Ordering::Relaxed);
-                let stale = (w.generation < self.current_generation()) as usize;
-                (stale, degraded as usize)
-            });
+            if self.me_deterministic_writer_sort.load(Ordering::Relaxed) {
+                candidate_indices.sort_by(|lhs, rhs| {
+                    let left = &writers_snapshot[*lhs];
+                    let right = &writers_snapshot[*rhs];
+                    let left_key = (
+                        self.writer_contour_rank_for_selection(left),
+                        (left.generation < self.current_generation()) as usize,
+                        left.degraded.load(Ordering::Relaxed) as usize,
+                        Reverse(left.tx.capacity()),
+                        left.addr,
+                        left.id,
+                    );
+                    let right_key = (
+                        self.writer_contour_rank_for_selection(right),
+                        (right.generation < self.current_generation()) as usize,
+                        right.degraded.load(Ordering::Relaxed) as usize,
+                        Reverse(right.tx.capacity()),
+                        right.addr,
+                        right.id,
+                    );
+                    left_key.cmp(&right_key)
+                });
+            } else {
+                candidate_indices.sort_by_key(|idx| {
+                    let w = &writers_snapshot[*idx];
+                    let degraded = w.degraded.load(Ordering::Relaxed);
+                    let stale = (w.generation < self.current_generation()) as usize;
+                    (
+                        self.writer_contour_rank_for_selection(w),
+                        stale,
+                        degraded as usize,
+                        Reverse(w.tx.capacity()),
+                    )
+                });
+            }
 
             let start = self.rr.fetch_add(1, Ordering::Relaxed) as usize % candidate_indices.len();
+            let mut fallback_blocking_idx: Option<usize> = None;
 
             for offset in 0..candidate_indices.len() {
                 let idx = candidate_indices[(start + offset) % candidate_indices.len()];
@@ -146,29 +198,41 @@ impl MePool {
                 if !self.writer_accepts_new_binding(w) {
                     continue;
                 }
-                if w.tx.send(WriterCommand::Data(payload.clone())).await.is_ok() {
-                    self.registry
-                        .bind_writer(conn_id, w.id, w.tx.clone(), meta.clone())
-                        .await;
-                    if w.generation < self.current_generation() {
-                        self.stats.increment_pool_stale_pick_total();
-                        debug!(
-                            conn_id,
-                            writer_id = w.id,
-                            writer_generation = w.generation,
-                            current_generation = self.current_generation(),
-                            "Selected stale ME writer for fallback bind"
-                        );
+                match w.tx.try_send(WriterCommand::Data(payload.clone())) {
+                    Ok(()) => {
+                        self.registry
+                            .bind_writer(conn_id, w.id, w.tx.clone(), meta.clone())
+                            .await;
+                        if w.generation < self.current_generation() {
+                            self.stats.increment_pool_stale_pick_total();
+                            debug!(
+                                conn_id,
+                                writer_id = w.id,
+                                writer_generation = w.generation,
+                                current_generation = self.current_generation(),
+                                "Selected stale ME writer for fallback bind"
+                            );
+                        }
+                        return Ok(());
+                    }
+                    Err(TrySendError::Full(_)) => {
+                        if fallback_blocking_idx.is_none() {
+                            fallback_blocking_idx = Some(idx);
+                        }
+                    }
+                    Err(TrySendError::Closed(_)) => {
+                        warn!(writer_id = w.id, "ME writer channel closed");
+                        self.remove_writer_and_close_clients(w.id).await;
+                        continue;
                     }
-                    return Ok(());
-                } else {
-                    warn!(writer_id = w.id, "ME writer channel closed");
-                    self.remove_writer_and_close_clients(w.id).await;
-                    continue;
                 }
             }
 
-            let w = writers_snapshot[candidate_indices[start]].clone();
+            let Some(blocking_idx) = fallback_blocking_idx else {
+                continue;
+            };
+
+            let w = writers_snapshot[blocking_idx].clone();
             if !self.writer_accepts_new_binding(&w) {
                 continue;
             }
@@ -215,6 +279,7 @@ impl MePool {
         &self,
         writers: &[super::pool::MeWriter],
         target_dc: i16,
+        include_warm: bool,
     ) -> Vec<usize> {
         let key = target_dc as i32;
         let mut preferred = Vec::<SocketAddr>::new();
@@ -258,13 +323,13 @@ impl MePool {
 
         if preferred.is_empty() {
             return (0..writers.len())
-                .filter(|i| self.writer_accepts_new_binding(&writers[*i]))
+                .filter(|i| self.writer_eligible_for_selection(&writers[*i], include_warm))
                 .collect();
         }
 
         let mut out = Vec::new();
         for (idx, w) in writers.iter().enumerate() {
-            if !self.writer_accepts_new_binding(w) {
+            if !self.writer_eligible_for_selection(w, include_warm) {
                 continue;
             }
             if preferred.contains(&w.addr) {
@@ -273,10 +338,33 @@ impl MePool {
         }
         if out.is_empty() {
             return (0..writers.len())
-                .filter(|i| self.writer_accepts_new_binding(&writers[*i]))
+                .filter(|i| self.writer_eligible_for_selection(&writers[*i], include_warm))
                 .collect();
         }
         out
     }
 
+    fn writer_eligible_for_selection(
+        &self,
+        writer: &super::pool::MeWriter,
+        include_warm: bool,
+    ) -> bool {
+        if !self.writer_accepts_new_binding(writer) {
+            return false;
+        }
+
+        match WriterContour::from_u8(writer.contour.load(Ordering::Relaxed)) {
+            WriterContour::Active => true,
+            WriterContour::Warm => include_warm,
+            WriterContour::Draining => true,
+        }
+    }
+
+    fn writer_contour_rank_for_selection(&self, writer: &super::pool::MeWriter) -> usize {
+        match WriterContour::from_u8(writer.contour.load(Ordering::Relaxed)) {
+            WriterContour::Active => 0,
+            WriterContour::Warm => 1,
+            WriterContour::Draining => 2,
+        }
+    }
 }

src/transport/upstream.rs

@@ -4,7 +4,7 @@
 
 #![allow(deprecated)]
 
-use std::collections::HashMap;
+use std::collections::{BTreeSet, HashMap};
 use std::net::{SocketAddr, IpAddr};
 use std::sync::Arc;
 use std::sync::atomic::{AtomicUsize, Ordering};
@@ -29,6 +29,12 @@ const NUM_DCS: usize = 5;
 const DC_PING_TIMEOUT_SECS: u64 = 5;
 /// Timeout for direct TG DC TCP connect readiness.
 const DIRECT_CONNECT_TIMEOUT_SECS: u64 = 10;
+/// Interval between upstream health-check cycles.
+const HEALTH_CHECK_INTERVAL_SECS: u64 = 30;
+/// Timeout for a single health-check connect attempt.
+const HEALTH_CHECK_CONNECT_TIMEOUT_SECS: u64 = 10;
+/// Upstream is considered healthy when at least this many DC groups are reachable.
+const MIN_HEALTHY_DC_GROUPS: usize = 3;
 
 // ============= RTT Tracking =============
 
@@ -167,6 +173,13 @@ pub struct UpstreamEgressInfo {
     pub socks_proxy_addr: Option<SocketAddr>,
 }
 
+#[derive(Debug, Clone)]
+struct HealthCheckGroup {
+    dc_idx: i16,
+    primary: Vec<SocketAddr>,
+    fallback: Vec<SocketAddr>,
+}
+
 // ============= Upstream Manager =============
 
 #[derive(Clone)]
@@ -987,41 +1000,144 @@ impl UpstreamManager {
         Ok(start.elapsed().as_secs_f64() * 1000.0)
     }
 
+    fn required_healthy_group_count(total_groups: usize) -> usize {
+        if total_groups == 0 {
+            0
+        } else {
+            total_groups.min(MIN_HEALTHY_DC_GROUPS)
+        }
+    }
+
+    fn build_health_check_groups(
+        prefer_ipv6: bool,
+        ipv4_enabled: bool,
+        ipv6_enabled: bool,
+        dc_overrides: &HashMap<String, Vec<String>>,
+    ) -> Vec<HealthCheckGroup> {
+        let mut v4_by_dc: HashMap<i16, Vec<SocketAddr>> = HashMap::new();
+        let mut v6_by_dc: HashMap<i16, Vec<SocketAddr>> = HashMap::new();
+
+        if ipv4_enabled {
+            for (idx, dc_ip) in TG_DATACENTERS_V4.iter().enumerate() {
+                let dc_idx = (idx + 1) as i16;
+                v4_by_dc
+                    .entry(dc_idx)
+                    .or_default()
+                    .push(SocketAddr::new(*dc_ip, TG_DATACENTER_PORT));
+            }
+        }
+
+        if ipv6_enabled {
+            for (idx, dc_ip) in TG_DATACENTERS_V6.iter().enumerate() {
+                let dc_idx = (idx + 1) as i16;
+                v6_by_dc
+                    .entry(dc_idx)
+                    .or_default()
+                    .push(SocketAddr::new(*dc_ip, TG_DATACENTER_PORT));
+            }
+        }
+
+        for (dc_key, addrs) in dc_overrides {
+            let dc_idx = match dc_key.parse::<i16>() {
+                Ok(v) if v > 0 => v,
+                _ => {
+                    warn!(dc = %dc_key, "Invalid dc_overrides key for health-check, skipping");
+                    continue;
+                }
+            };
+
+            for addr_str in addrs {
+                match addr_str.parse::<SocketAddr>() {
+                    Ok(addr) if addr.is_ipv6() => {
+                        if ipv6_enabled {
+                            v6_by_dc.entry(dc_idx).or_default().push(addr);
+                        }
+                    }
+                    Ok(addr) => {
+                        if ipv4_enabled {
+                            v4_by_dc.entry(dc_idx).or_default().push(addr);
+                        }
+                    }
+                    Err(_) => {
+                        warn!(
+                            dc = %dc_idx,
+                            addr = %addr_str,
+                            "Invalid dc_overrides address for health-check, skipping"
+                        );
+                    }
+                }
+            }
+        }
+
+        for addrs in v4_by_dc.values_mut() {
+            addrs.sort_unstable();
+            addrs.dedup();
+        }
+        for addrs in v6_by_dc.values_mut() {
+            addrs.sort_unstable();
+            addrs.dedup();
+        }
+
+        let mut all_dcs = BTreeSet::new();
+        all_dcs.extend(v4_by_dc.keys().copied());
+        all_dcs.extend(v6_by_dc.keys().copied());
+
+        let mut groups = Vec::with_capacity(all_dcs.len());
+        for dc_idx in all_dcs {
+            let v4_endpoints = v4_by_dc.remove(&dc_idx).unwrap_or_default();
+            let v6_endpoints = v6_by_dc.remove(&dc_idx).unwrap_or_default();
+            let (primary, fallback) = if prefer_ipv6 {
+                (v6_endpoints, v4_endpoints)
+            } else {
+                (v4_endpoints, v6_endpoints)
+            };
+
+            if primary.is_empty() && fallback.is_empty() {
+                continue;
+            }
+
+            groups.push(HealthCheckGroup {
+                dc_idx,
+                primary,
+                fallback,
+            });
+        }
+
+        groups
+    }
+
     // ============= Health Checks =============
 
-    /// Background health check: rotates through DCs, 30s interval.
-    /// Uses preferred IP version based on config.
-    pub async fn run_health_checks(&self, prefer_ipv6: bool, ipv4_enabled: bool, ipv6_enabled: bool) {
-        let mut dc_rotation = 0usize;
+    /// Background health check based on reachable DC groups through each upstream.
+    /// Upstream stays healthy while at least `MIN_HEALTHY_DC_GROUPS` groups are reachable.
+    pub async fn run_health_checks(
+        &self,
+        prefer_ipv6: bool,
+        ipv4_enabled: bool,
+        ipv6_enabled: bool,
+        dc_overrides: HashMap<String, Vec<String>>,
+    ) {
+        let groups = Self::build_health_check_groups(
+            prefer_ipv6,
+            ipv4_enabled,
+            ipv6_enabled,
+            &dc_overrides,
+        );
+        let required_healthy_groups = Self::required_healthy_group_count(groups.len());
+        let mut endpoint_rotation: HashMap<(usize, i16, bool), usize> = HashMap::new();
+
+        if groups.is_empty() {
+            warn!("No DC groups available for upstream health-checks");
+        }
 
         loop {
-            tokio::time::sleep(Duration::from_secs(30)).await;
+            tokio::time::sleep(Duration::from_secs(HEALTH_CHECK_INTERVAL_SECS)).await;
 
-            let dc_zero_idx = dc_rotation % NUM_DCS;
-            dc_rotation += 1;
-
-            let primary_v6 = SocketAddr::new(TG_DATACENTERS_V6[dc_zero_idx], TG_DATACENTER_PORT);
-            let primary_v4 = SocketAddr::new(TG_DATACENTERS_V4[dc_zero_idx], TG_DATACENTER_PORT);
-            let dc_addr = if prefer_ipv6 && ipv6_enabled {
-                primary_v6
-            } else if ipv4_enabled {
-                primary_v4
-            } else if ipv6_enabled {
-                primary_v6
-            } else {
+            if groups.is_empty() || required_healthy_groups == 0 {
                 continue;
-            };
-
-            let fallback_addr = if dc_addr.is_ipv6() && ipv4_enabled {
-                Some(primary_v4)
-            } else if dc_addr.is_ipv4() && ipv6_enabled {
-                Some(primary_v6)
-            } else {
-                None
-            };
+            }
 
             let count = self.upstreams.read().await.len();
-
             for i in 0..count {
                 let (config, bind_rr) = {
                     let guard = self.upstreams.read().await;
@@ -1029,104 +1145,123 @@ impl UpstreamManager {
                     (u.config.clone(), u.bind_rr.clone())
                 };
 
-                let start = Instant::now();
-                let result = tokio::time::timeout(
-                    Duration::from_secs(10),
-                    self.connect_via_upstream(&config, dc_addr, Some(bind_rr.clone()))
-                ).await;
+                let mut healthy_groups = 0usize;
+                let mut latency_updates: Vec<(usize, f64)> = Vec::new();
 
-                match result {
-                    Ok(Ok(_stream)) => {
-                        let rtt_ms = start.elapsed().as_secs_f64() * 1000.0;
-                        let mut guard = self.upstreams.write().await;
-                        let u = &mut guard[i];
-                        u.dc_latency[dc_zero_idx].update(rtt_ms);
+                for group in &groups {
+                    let mut group_ok = false;
+                    let mut group_rtt_ms = None;
 
-                        if !u.healthy {
-                            info!(
-                                rtt = format!("{:.0} ms", rtt_ms),
-                                dc = dc_zero_idx + 1,
-                                "Upstream recovered"
-                            );
-                        }
-                        u.healthy = true;
-                        u.fails = 0;
-                        u.last_check = std::time::Instant::now();
-                    }
-                    Ok(Err(_)) | Err(_) => {
-                        // Try fallback
-                        debug!(dc = dc_zero_idx + 1, "Health check failed, trying fallback");
-
-                        if let Some(fallback_addr) = fallback_addr {
-                            let start2 = Instant::now();
-                            let result2 = tokio::time::timeout(
-                                Duration::from_secs(10),
-                                self.connect_via_upstream(&config, fallback_addr, Some(bind_rr.clone()))
-                            ).await;
-
-                            let mut guard = self.upstreams.write().await;
-                            let u = &mut guard[i];
-
-                            match result2 {
-                                Ok(Ok(_stream)) => {
-                                    let rtt_ms = start2.elapsed().as_secs_f64() * 1000.0;
-                                    u.dc_latency[dc_zero_idx].update(rtt_ms);
-
-                                    if !u.healthy {
-                                        info!(
-                                            rtt = format!("{:.0} ms", rtt_ms),
-                                            dc = dc_zero_idx + 1,
-                                            "Upstream recovered (fallback)"
-                                        );
-                                    }
-                                    u.healthy = true;
-                                    u.fails = 0;
-                                }
-                                Ok(Err(e)) => {
-                                    u.fails += 1;
-                                    debug!(dc = dc_zero_idx + 1, fails = u.fails,
-                                        "Health check failed (both): {}", e);
-                                    if u.fails >= self.unhealthy_fail_threshold {
-                                        u.healthy = false;
-                                        warn!(
-                                            fails = u.fails,
-                                            threshold = self.unhealthy_fail_threshold,
-                                            "Upstream unhealthy (fails)"
-                                        );
-                                    }
-                                }
-                                Err(_) => {
-                                    u.fails += 1;
-                                    debug!(dc = dc_zero_idx + 1, fails = u.fails,
-                                        "Health check timeout (both)");
-                                    if u.fails >= self.unhealthy_fail_threshold {
-                                        u.healthy = false;
-                                        warn!(
-                                            fails = u.fails,
-                                            threshold = self.unhealthy_fail_threshold,
-                                            "Upstream unhealthy (timeout)"
-                                        );
-                                    }
-                                }
-                            }
-                            u.last_check = std::time::Instant::now();
+                    for (is_primary, endpoints) in [(true, &group.primary), (false, &group.fallback)] {
+                        if endpoints.is_empty() {
                             continue;
                         }
 
-                        let mut guard = self.upstreams.write().await;
-                        let u = &mut guard[i];
-                        u.fails += 1;
-                        if u.fails >= self.unhealthy_fail_threshold {
-                            u.healthy = false;
-                            warn!(
-                                fails = u.fails,
-                                threshold = self.unhealthy_fail_threshold,
-                                "Upstream unhealthy (no fallback family)"
-                            );
+                        let rotation_key = (i, group.dc_idx, is_primary);
+                        let start_idx = *endpoint_rotation.entry(rotation_key).or_insert(0) % endpoints.len();
+                        let mut next_idx = (start_idx + 1) % endpoints.len();
+
+                        for step in 0..endpoints.len() {
+                            let endpoint_idx = (start_idx + step) % endpoints.len();
+                            let endpoint = endpoints[endpoint_idx];
+
+                            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())),
+                            )
+                            .await;
+
+                            match result {
+                                Ok(Ok(_stream)) => {
+                                    group_ok = true;
+                                    group_rtt_ms = Some(start.elapsed().as_secs_f64() * 1000.0);
+                                    next_idx = (endpoint_idx + 1) % endpoints.len();
+                                    break;
+                                }
+                                Ok(Err(e)) => {
+                                    debug!(
+                                        upstream = i,
+                                        dc = group.dc_idx,
+                                        endpoint = %endpoint,
+                                        primary = is_primary,
+                                        error = %e,
+                                        "Health-check endpoint failed"
+                                    );
+                                }
+                                Err(_) => {
+                                    debug!(
+                                        upstream = i,
+                                        dc = group.dc_idx,
+                                        endpoint = %endpoint,
+                                        primary = is_primary,
+                                        "Health-check endpoint timed out"
+                                    );
+                                }
+                            }
+                        }
+
+                        endpoint_rotation.insert(rotation_key, next_idx);
+
+                        if group_ok {
+                            break;
+                        }
+                    }
+
+                    if group_ok {
+                        healthy_groups += 1;
+                        if let (Some(dc_array_idx), Some(rtt_ms)) =
+                            (UpstreamState::dc_array_idx(group.dc_idx), group_rtt_ms)
+                        {
+                            latency_updates.push((dc_array_idx, rtt_ms));
                         }
-                        u.last_check = std::time::Instant::now();
                     }
                 }
+
+                let mut guard = self.upstreams.write().await;
+                let u = &mut guard[i];
+
+                for (dc_array_idx, rtt_ms) in latency_updates {
+                    u.dc_latency[dc_array_idx].update(rtt_ms);
+                }
+
+                if healthy_groups >= required_healthy_groups {
+                    if !u.healthy {
+                        info!(
+                            upstream = i,
+                            healthy_groups,
+                            total_groups = groups.len(),
+                            required_groups = required_healthy_groups,
+                            "Upstream recovered by DC-group health threshold"
+                        );
+                    }
+                    u.healthy = true;
+                    u.fails = 0;
+                } else {
+                    u.fails += 1;
+                    debug!(
+                        upstream = i,
+                        healthy_groups,
+                        total_groups = groups.len(),
+                        required_groups = required_healthy_groups,
+                        fails = u.fails,
+                        "Upstream health-check below DC-group threshold"
+                    );
+                    if u.fails >= self.unhealthy_fail_threshold {
+                        u.healthy = false;
+                        warn!(
+                            upstream = i,
+                            healthy_groups,
+                            total_groups = groups.len(),
+                            required_groups = required_healthy_groups,
+                            fails = u.fails,
+                            threshold = self.unhealthy_fail_threshold,
+                            "Upstream unhealthy (insufficient reachable DC groups)"
+                        );
+                    }
+                }
+
+                u.last_check = std::time::Instant::now();
             }
         }
     }
@@ -1157,3 +1292,76 @@ impl UpstreamManager {
         Some(SocketAddr::new(ip, TG_DATACENTER_PORT))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn required_healthy_group_count_applies_three_group_threshold() {
+        assert_eq!(UpstreamManager::required_healthy_group_count(0), 0);
+        assert_eq!(UpstreamManager::required_healthy_group_count(1), 1);
+        assert_eq!(UpstreamManager::required_healthy_group_count(2), 2);
+        assert_eq!(UpstreamManager::required_healthy_group_count(3), 3);
+        assert_eq!(UpstreamManager::required_healthy_group_count(5), 3);
+    }
+
+    #[test]
+    fn build_health_check_groups_merges_family_endpoints_with_preference() {
+        let mut overrides = HashMap::new();
+        overrides.insert(
+            "2".to_string(),
+            vec![
+                "203.0.113.10:443".to_string(),
+                "203.0.113.11:443".to_string(),
+                "[2001:db8::10]:443".to_string(),
+            ],
+        );
+
+        let groups = UpstreamManager::build_health_check_groups(true, true, true, &overrides);
+        let dc2 = groups
+            .iter()
+            .find(|g| g.dc_idx == 2)
+            .expect("dc2 must be present");
+
+        assert!(dc2.primary.iter().all(|addr| addr.is_ipv6()));
+        assert!(dc2.fallback.iter().all(|addr| addr.is_ipv4()));
+        assert!(dc2
+            .primary
+            .contains(&"[2001:db8::10]:443".parse::<SocketAddr>().unwrap()));
+        assert!(dc2
+            .fallback
+            .contains(&"203.0.113.10:443".parse::<SocketAddr>().unwrap()));
+        assert!(dc2
+            .fallback
+            .contains(&"203.0.113.11:443".parse::<SocketAddr>().unwrap()));
+    }
+
+    #[test]
+    fn build_health_check_groups_keeps_multiple_endpoints_per_group() {
+        let mut overrides = HashMap::new();
+        overrides.insert(
+            "9".to_string(),
+            vec![
+                "198.51.100.1:443".to_string(),
+                "198.51.100.2:443".to_string(),
+                "198.51.100.1:443".to_string(),
+            ],
+        );
+
+        let groups = UpstreamManager::build_health_check_groups(false, true, false, &overrides);
+        let dc9 = groups
+            .iter()
+            .find(|g| g.dc_idx == 9)
+            .expect("override-only dc group must be present");
+
+        assert_eq!(dc9.primary.len(), 2);
+        assert!(dc9
+            .primary
+            .contains(&"198.51.100.1:443".parse::<SocketAddr>().unwrap()));
+        assert!(dc9
+            .primary
+            .contains(&"198.51.100.2:443".parse::<SocketAddr>().unwrap()));
+        assert!(dc9.fallback.is_empty());
+    }
+}