ServerHello fixes + Docker Health-Check + Conntrack Control for Docker: merge pull request #717 from telemt/flow

ServerHello fixes + Docker Health-Check + Conntrack Control for Docker

Cargo.lock

@@ -2780,7 +2780,7 @@ checksum = "7b2093cf4c8eb1e67749a6762251bc9cd836b6fc171623bd0a9d324d37af2417"
 
 [[package]]
 name = "telemt"
-version = "3.4.0"
+version = "3.4.3"
 dependencies = [
  "aes",
  "anyhow",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "telemt"
-version = "3.4.0"
+version = "3.4.3"
 edition = "2024"
 
 [features]

Dockerfile

@@ -77,6 +77,34 @@ COPY config.toml /app/config.toml
 
 EXPOSE 443 9090 9091
 
+HEALTHCHECK --interval=30s --timeout=5s --start-period=20s --retries=3 CMD ["/app/telemt", "healthcheck", "/app/config.toml", "--mode", "liveness"]
+
+ENTRYPOINT ["/app/telemt"]
+CMD ["config.toml"]
+
+# ==========================
+# Production Netfilter Profile
+# ==========================
+FROM debian:12-slim AS prod-netfilter
+
+RUN set -eux; \
+    apt-get update; \
+    apt-get install -y --no-install-recommends \
+        ca-certificates \
+        conntrack \
+        nftables \
+        iptables; \
+    rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+COPY --from=minimal /telemt /app/telemt
+COPY config.toml /app/config.toml
+
+EXPOSE 443 9090 9091
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=20s --retries=3 CMD ["/app/telemt", "healthcheck", "/app/config.toml", "--mode", "liveness"]
+
 ENTRYPOINT ["/app/telemt"]
 CMD ["config.toml"]
 
@@ -94,5 +122,7 @@ USER nonroot:nonroot
 
 EXPOSE 443 9090 9091
 
+HEALTHCHECK --interval=30s --timeout=5s --start-period=20s --retries=3 CMD ["/app/telemt", "healthcheck", "/app/config.toml", "--mode", "liveness"]
+
 ENTRYPOINT ["/app/telemt"]
 CMD ["config.toml"]

README.md

@@ -1,6 +1,6 @@
 # Telemt - MTProxy on Rust + Tokio
 
-![Latest Release](https://img.shields.io/github/v/release/telemt/telemt?color=neon) ![Stars](https://img.shields.io/github/stars/telemt/telemt?style=social) ![Forks](https://img.shields.io/github/forks/telemt/telemt?style=social) [![Telegram](https://img.shields.io/badge/Telegram-Chat-24a1de?logo=telegram&logoColor=24a1de)](https://t.me/telemtrs)
+[![Latest Release](https://img.shields.io/github/v/release/telemt/telemt?color=neon)](https://github.com/telemt/telemt/releases/latest) [![Stars](https://img.shields.io/github/stars/telemt/telemt?style=social)](https://github.com/telemt/telemt/stargazers) [![Forks](https://img.shields.io/github/forks/telemt/telemt?style=social)](https://github.com/telemt/telemt/network/members) [![Telegram](https://img.shields.io/badge/Telegram-Chat-24a1de?logo=telegram&logoColor=24a1de)](https://t.me/telemtrs)
 
 [🇷🇺 README на русском](https://github.com/telemt/telemt/blob/main/README.ru.md)
 

README.ru.md

@@ -1,6 +1,6 @@
 # Telemt — MTProxy на Rust + Tokio
 
-![Latest Release](https://img.shields.io/github/v/release/telemt/telemt?color=neon) ![Stars](https://img.shields.io/github/stars/telemt/telemt?style=social) ![Forks](https://img.shields.io/github/forks/telemt/telemt?style=social) [![Telegram](https://img.shields.io/badge/Telegram-Chat-24a1de?logo=telegram&logoColor=24a1de)](https://t.me/telemtrs)
+[![Latest Release](https://img.shields.io/github/v/release/telemt/telemt?color=neon)](https://github.com/telemt/telemt/releases/latest) [![Stars](https://img.shields.io/github/stars/telemt/telemt?style=social)](https://github.com/telemt/telemt/stargazers) [![Forks](https://img.shields.io/github/forks/telemt/telemt?style=social)](https://github.com/telemt/telemt/network/members) [![Telegram](https://img.shields.io/badge/Telegram-Chat-24a1de?logo=telegram&logoColor=24a1de)](https://t.me/telemtrs)
 
 ***Решает проблемы раньше, чем другие узнают об их существовании***
 

docker-compose.host-netfilter.yml

@@ -0,0 +1,10 @@
+services:
+  telemt:
+    build:
+      context: .
+      target: prod-netfilter
+    network_mode: host
+    ports: []
+    cap_add:
+      - NET_BIND_SERVICE
+      - NET_ADMIN

docker-compose.netfilter.yml

@@ -0,0 +1,8 @@
+services:
+  telemt:
+    build:
+      context: .
+      target: prod-netfilter
+    cap_add:
+      - NET_BIND_SERVICE
+      - NET_ADMIN

docker-compose.yml

@@ -1,7 +1,9 @@
 services:
   telemt:
     image: ghcr.io/telemt/telemt:latest
-    build: .
+    build:
+      context: .
+      target: prod
     container_name: telemt
     restart: unless-stopped
     ports:
@@ -16,13 +18,18 @@ services:
       - /etc/telemt:rw,mode=1777,size=4m
     environment:
       - RUST_LOG=info
+    healthcheck:
+      test: [ "CMD", "/app/telemt", "healthcheck", "/etc/telemt/config.toml", "--mode", "liveness" ]
+      interval: 30s
+      timeout: 5s
+      retries: 3
+      start_period: 20s
     # Uncomment this line if you want to use host network for IPv6, but bridge is default and usually better
     # network_mode: host
     cap_drop:
       - ALL
     cap_add:
       - NET_BIND_SERVICE
-      - NET_ADMIN
     read_only: true
     security_opt:
       - no-new-privileges:true

docs/Setup_examples/XRAY_DOUBLE_HOP.en.md

@@ -37,13 +37,13 @@ xray x25519
 ```
 3. **Short ID (Reality identifier):**
 ```bash
-openssl rand -hex 16
-# Save the output (e.g.: 0123456789abcdef0123456789abcdef) — this is <SHORT_ID>
+openssl rand -hex 8
+# Save the output (e.g.: abc123def456) — this is <SHORT_ID>
 ```
 4. **Random Path (for xhttp):**
 ```bash
-openssl rand -hex 8
-# Save the output (e.g., abc123def456) to replace <YOUR_RANDOM_PATH> in configs
+openssl rand -hex 16
+# Save the output (e.g., 0123456789abcdef0123456789abcdef) to replace <YOUR_RANDOM_PATH> in configs
 ```
 
 ---

docs/Setup_examples/XRAY_DOUBLE_HOP.ru.md

@@ -37,13 +37,13 @@ xray x25519
 ```
 3. **Short ID (идентификатор Reality):**
 ```bash
-openssl rand -hex 16
-# Сохраните вывод (например: 0123456789abcdef0123456789abcdef) — это <SHORT_ID>
+openssl rand -hex 8
+# Сохраните вывод (например: abc123def456) — это <SHORT_ID>
 ```
 4. **Random Path (путь для xhttp):**
 ```bash
-openssl rand -hex 8
-# Сохраните вывод (например, abc123def456), чтобы заменить <YOUR_RANDOM_PATH> в конфигах
+openssl rand -hex 16
+# Сохраните вывод (например, 0123456789abcdef0123456789abcdef), чтобы заменить <YOUR_RANDOM_PATH> в конфигах
 ```
 
 ---

src/api/mod.rs

@@ -41,8 +41,8 @@ use config_store::{current_revision, load_config_from_disk, parse_if_match};
 use events::ApiEventStore;
 use http_utils::{error_response, read_json, read_optional_json, success_response};
 use model::{
-    ApiFailure, CreateUserRequest, DeleteUserResponse, HealthData, PatchUserRequest,
-    RotateSecretRequest, SummaryData, UserActiveIps,
+    ApiFailure, CreateUserRequest, DeleteUserResponse, HealthData, HealthReadyData,
+    PatchUserRequest, RotateSecretRequest, SummaryData, UserActiveIps,
 };
 use runtime_edge::{
     EdgeConnectionsCacheEntry, build_runtime_connections_summary_data,
@@ -275,6 +275,33 @@ async fn handle(
                 };
                 Ok(success_response(StatusCode::OK, data, revision))
             }
+            ("GET", "/v1/health/ready") => {
+                let revision = current_revision(&shared.config_path).await?;
+                let admission_open = shared.runtime_state.admission_open.load(Ordering::Relaxed);
+                let upstream_health = shared.upstream_manager.api_health_summary().await;
+                let ready = admission_open && upstream_health.healthy_total > 0;
+                let reason = if ready {
+                    None
+                } else if !admission_open {
+                    Some("admission_closed")
+                } else {
+                    Some("no_healthy_upstreams")
+                };
+                let data = HealthReadyData {
+                    ready,
+                    status: if ready { "ready" } else { "not_ready" },
+                    reason,
+                    admission_open,
+                    healthy_upstreams: upstream_health.healthy_total,
+                    total_upstreams: upstream_health.configured_total,
+                };
+                let status_code = if ready {
+                    StatusCode::OK
+                } else {
+                    StatusCode::SERVICE_UNAVAILABLE
+                };
+                Ok(success_response(status_code, data, revision))
+            }
             ("GET", "/v1/system/info") => {
                 let revision = current_revision(&shared.config_path).await?;
                 let data = build_system_info_data(shared.as_ref(), cfg.as_ref(), &revision);

src/api/model.rs

@@ -60,6 +60,17 @@ pub(super) struct HealthData {
     pub(super) read_only: bool,
 }
 
+#[derive(Serialize)]
+pub(super) struct HealthReadyData {
+    pub(super) ready: bool,
+    pub(super) status: &'static str,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) reason: Option<&'static str>,
+    pub(super) admission_open: bool,
+    pub(super) healthy_upstreams: usize,
+    pub(super) total_upstreams: usize,
+}
+
 #[derive(Serialize)]
 pub(super) struct SummaryData {
     pub(super) uptime_seconds: f64,

src/cli.rs

@@ -6,12 +6,15 @@
 //! - `reload [--pid-file PATH]` - Reload configuration (SIGHUP)
 //! - `status [--pid-file PATH]` - Check daemon status
 //! - `run [OPTIONS] [config.toml]` - Run in foreground (default behavior)
+//! - `healthcheck [OPTIONS] [config.toml]` - Run control-plane health probe
 
 use rand::RngExt;
 use std::fs;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
+use crate::healthcheck::{self, HealthcheckMode};
+
 #[cfg(unix)]
 use crate::daemon::{self, DEFAULT_PID_FILE, DaemonOptions};
 
@@ -28,6 +31,8 @@ pub enum Subcommand {
     Reload,
     /// Check daemon status (`status` subcommand).
     Status,
+    /// Run health probe and exit with status code.
+    Healthcheck,
     /// Fire-and-forget setup (`--init`).
     Init,
 }
@@ -38,6 +43,8 @@ pub struct ParsedCommand {
     pub subcommand: Subcommand,
     pub pid_file: PathBuf,
     pub config_path: String,
+    pub healthcheck_mode: HealthcheckMode,
+    pub healthcheck_mode_invalid: Option<String>,
     #[cfg(unix)]
     pub daemon_opts: DaemonOptions,
     pub init_opts: Option<InitOptions>,
@@ -52,6 +59,8 @@ impl Default for ParsedCommand {
             #[cfg(not(unix))]
             pid_file: PathBuf::from("/var/run/telemt.pid"),
             config_path: "config.toml".to_string(),
+            healthcheck_mode: HealthcheckMode::Liveness,
+            healthcheck_mode_invalid: None,
             #[cfg(unix)]
             daemon_opts: DaemonOptions::default(),
             init_opts: None,
@@ -91,6 +100,9 @@ pub fn parse_command(args: &[String]) -> ParsedCommand {
             "status" => {
                 cmd.subcommand = Subcommand::Status;
             }
+            "healthcheck" => {
+                cmd.subcommand = Subcommand::Healthcheck;
+            }
             "run" => {
                 cmd.subcommand = Subcommand::Run;
                 #[cfg(unix)]
@@ -113,7 +125,35 @@ pub fn parse_command(args: &[String]) -> ParsedCommand {
     while i < args.len() {
         match args[i].as_str() {
             // Skip subcommand names
-            "start" | "stop" | "reload" | "status" | "run" => {}
+            "start" | "stop" | "reload" | "status" | "run" | "healthcheck" => {}
+            "--mode" => {
+                i += 1;
+                if i < args.len() {
+                    match HealthcheckMode::from_cli_arg(&args[i]) {
+                        Some(mode) => {
+                            cmd.healthcheck_mode = mode;
+                            cmd.healthcheck_mode_invalid = None;
+                        }
+                        None => {
+                            cmd.healthcheck_mode_invalid = Some(args[i].clone());
+                        }
+                    }
+                } else {
+                    cmd.healthcheck_mode_invalid = Some(String::new());
+                }
+            }
+            s if s.starts_with("--mode=") => {
+                let raw = s.trim_start_matches("--mode=");
+                match HealthcheckMode::from_cli_arg(raw) {
+                    Some(mode) => {
+                        cmd.healthcheck_mode = mode;
+                        cmd.healthcheck_mode_invalid = None;
+                    }
+                    None => {
+                        cmd.healthcheck_mode_invalid = Some(raw.to_string());
+                    }
+                }
+            }
             // PID file option (for stop/reload/status)
             "--pid-file" => {
                 i += 1;
@@ -152,6 +192,20 @@ pub fn execute_subcommand(cmd: &ParsedCommand) -> Option<i32> {
         Subcommand::Stop => Some(cmd_stop(&cmd.pid_file)),
         Subcommand::Reload => Some(cmd_reload(&cmd.pid_file)),
         Subcommand::Status => Some(cmd_status(&cmd.pid_file)),
+        Subcommand::Healthcheck => {
+            if let Some(invalid_mode) = cmd.healthcheck_mode_invalid.as_ref() {
+                if invalid_mode.is_empty() {
+                    eprintln!("[telemt] Missing value for --mode (supported: liveness, ready)");
+                } else {
+                    eprintln!(
+                        "[telemt] Invalid --mode value '{invalid_mode}' (supported: liveness, ready)"
+                    );
+                }
+                Some(2)
+            } else {
+                Some(healthcheck::run(&cmd.config_path, cmd.healthcheck_mode))
+            }
+        }
         Subcommand::Init => {
             if let Some(opts) = cmd.init_opts.clone() {
                 match run_init(opts) {
@@ -177,6 +231,20 @@ pub fn execute_subcommand(cmd: &ParsedCommand) -> Option<i32> {
             eprintln!("[telemt] Subcommand not supported on this platform");
             Some(1)
         }
+        Subcommand::Healthcheck => {
+            if let Some(invalid_mode) = cmd.healthcheck_mode_invalid.as_ref() {
+                if invalid_mode.is_empty() {
+                    eprintln!("[telemt] Missing value for --mode (supported: liveness, ready)");
+                } else {
+                    eprintln!(
+                        "[telemt] Invalid --mode value '{invalid_mode}' (supported: liveness, ready)"
+                    );
+                }
+                Some(2)
+            } else {
+                Some(healthcheck::run(&cmd.config_path, cmd.healthcheck_mode))
+            }
+        }
         Subcommand::Init => {
             if let Some(opts) = cmd.init_opts.clone() {
                 match run_init(opts) {

src/config/hot_reload.rs

@@ -122,7 +122,8 @@ pub struct HotFields {
     pub user_expirations: std::collections::HashMap<String, chrono::DateTime<chrono::Utc>>,
     pub user_data_quota: std::collections::HashMap<String, u64>,
     pub user_rate_limits: std::collections::HashMap<String, crate::config::RateLimitBps>,
-    pub cidr_rate_limits: std::collections::HashMap<ipnetwork::IpNetwork, crate::config::RateLimitBps>,
+    pub cidr_rate_limits:
+        std::collections::HashMap<ipnetwork::IpNetwork, crate::config::RateLimitBps>,
     pub user_max_unique_ips: std::collections::HashMap<String, usize>,
     pub user_max_unique_ips_global_each: usize,
     pub user_max_unique_ips_mode: crate::config::UserMaxUniqueIpsMode,

src/config/load.rs

@@ -343,6 +343,10 @@ impl ProxyConfig {
         let network_table = parsed_toml
             .get("network")
             .and_then(|value| value.as_table());
+        let server_table = parsed_toml.get("server").and_then(|value| value.as_table());
+        let conntrack_control_table = server_table
+            .and_then(|table| table.get("conntrack_control"))
+            .and_then(|value| value.as_table());
         let update_every_is_explicit = general_table
             .map(|table| table.contains_key("update_every"))
             .unwrap_or(false);
@@ -372,10 +376,17 @@ impl ProxyConfig {
         let stun_servers_is_explicit = network_table
             .map(|table| table.contains_key("stun_servers"))
             .unwrap_or(false);
+        let inline_conntrack_control_is_explicit = conntrack_control_table
+            .map(|table| table.contains_key("inline_conntrack_control"))
+            .unwrap_or(false);
 
         let mut config: ProxyConfig = parsed_toml
             .try_into()
             .map_err(|e| ProxyError::Config(e.to_string()))?;
+        config
+            .server
+            .conntrack_control
+            .inline_conntrack_control_explicit = inline_conntrack_control_is_explicit;
 
         if !update_every_is_explicit && (legacy_secret_is_explicit || legacy_config_is_explicit) {
             config.general.update_every = None;
@@ -1881,6 +1892,43 @@ mod tests {
         );
     }
 
+    #[test]
+    fn conntrack_inline_explicit_flag_is_false_when_omitted() {
+        let cfg = load_config_from_temp_toml(
+            r#"
+            [general]
+            [network]
+            [server]
+            [server.conntrack_control]
+            [access]
+            "#,
+        );
+        assert!(
+            !cfg.server
+                .conntrack_control
+                .inline_conntrack_control_explicit
+        );
+    }
+
+    #[test]
+    fn conntrack_inline_explicit_flag_is_true_when_present() {
+        let cfg = load_config_from_temp_toml(
+            r#"
+            [general]
+            [network]
+            [server]
+            [server.conntrack_control]
+            inline_conntrack_control = true
+            [access]
+            "#,
+        );
+        assert!(
+            cfg.server
+                .conntrack_control
+                .inline_conntrack_control_explicit
+        );
+    }
+
     #[test]
     fn unknown_sni_action_parses_and_defaults_to_drop() {
         let cfg_default: ProxyConfig = toml::from_str(

src/config/types.rs

@@ -1329,6 +1329,10 @@ pub struct ConntrackControlConfig {
     #[serde(default = "default_conntrack_control_enabled")]
     pub inline_conntrack_control: bool,
 
+    /// Tracks whether inline_conntrack_control was explicitly set in config.
+    #[serde(skip)]
+    pub inline_conntrack_control_explicit: bool,
+
     /// Conntrack mode for listener ingress traffic.
     #[serde(default)]
     pub mode: ConntrackMode,
@@ -1363,6 +1367,7 @@ impl Default for ConntrackControlConfig {
     fn default() -> Self {
         Self {
             inline_conntrack_control: default_conntrack_control_enabled(),
+            inline_conntrack_control_explicit: false,
             mode: ConntrackMode::default(),
             backend: ConntrackBackend::default(),
             profile: ConntrackPressureProfile::default(),

src/conntrack_control.rs

@@ -24,6 +24,13 @@ enum NetfilterBackend {
     Iptables,
 }
 
+#[derive(Clone, Copy)]
+struct ConntrackRuntimeSupport {
+    netfilter_backend: Option<NetfilterBackend>,
+    has_cap_net_admin: bool,
+    has_conntrack_binary: bool,
+}
+
 #[derive(Clone, Copy)]
 struct PressureSample {
     conn_pct: Option<u8>,
@@ -56,11 +63,8 @@ pub(crate) fn spawn_conntrack_controller(
     shared: Arc<ProxySharedState>,
 ) {
     if !cfg!(target_os = "linux") {
-        let enabled = config_rx
-            .borrow()
-            .server
-            .conntrack_control
-            .inline_conntrack_control;
+        let cfg = config_rx.borrow();
+        let enabled = cfg.server.conntrack_control.inline_conntrack_control;
         stats.set_conntrack_control_enabled(enabled);
         stats.set_conntrack_control_available(false);
         stats.set_conntrack_pressure_active(false);
@@ -68,9 +72,14 @@ pub(crate) fn spawn_conntrack_controller(
         stats.set_conntrack_rule_apply_ok(false);
         shared.disable_conntrack_close_sender();
         shared.set_conntrack_pressure_active(false);
-        if enabled {
+        if enabled
+            && cfg
+                .server
+                .conntrack_control
+                .inline_conntrack_control_explicit
+        {
             warn!(
-                "conntrack control is configured but unsupported on this OS; disabling runtime worker"
+                "conntrack control explicitly enabled but unsupported on this OS; disabling runtime worker"
             );
         }
         return;
@@ -92,16 +101,17 @@ async fn run_conntrack_controller(
     let mut cfg = config_rx.borrow().clone();
     let mut pressure_state = PressureState::new(stats.as_ref());
     let mut delete_budget_tokens = cfg.server.conntrack_control.delete_budget_per_sec;
-    let mut backend = pick_backend(cfg.server.conntrack_control.backend);
+    let mut runtime_support = probe_runtime_support(cfg.server.conntrack_control.backend);
+    let mut effective_enabled = effective_conntrack_enabled(&cfg, runtime_support);
 
     apply_runtime_state(
         stats.as_ref(),
         shared.as_ref(),
         &cfg,
-        backend.is_some(),
+        runtime_support,
         false,
     );
-    reconcile_rules(&cfg, backend, stats.as_ref()).await;
+    reconcile_rules(&cfg, runtime_support, stats.as_ref()).await;
 
     loop {
         tokio::select! {
@@ -110,17 +120,18 @@ async fn run_conntrack_controller(
                     break;
                 }
                 cfg = config_rx.borrow_and_update().clone();
-                backend = pick_backend(cfg.server.conntrack_control.backend);
+                runtime_support = probe_runtime_support(cfg.server.conntrack_control.backend);
+                effective_enabled = effective_conntrack_enabled(&cfg, runtime_support);
                 delete_budget_tokens = cfg.server.conntrack_control.delete_budget_per_sec;
-                apply_runtime_state(stats.as_ref(), shared.as_ref(), &cfg, backend.is_some(), pressure_state.active);
-                reconcile_rules(&cfg, backend, stats.as_ref()).await;
+                apply_runtime_state(stats.as_ref(), shared.as_ref(), &cfg, runtime_support, pressure_state.active);
+                reconcile_rules(&cfg, runtime_support, stats.as_ref()).await;
             }
             event = close_rx.recv() => {
                 let Some(event) = event else {
                     break;
                 };
                 stats.set_conntrack_event_queue_depth(close_rx.len() as u64);
-                if !cfg.server.conntrack_control.inline_conntrack_control {
+                if !effective_enabled {
                     continue;
                 }
                 if !pressure_state.active {
@@ -156,6 +167,7 @@ async fn run_conntrack_controller(
                     stats.as_ref(),
                     shared.as_ref(),
                     &cfg,
+                    effective_enabled,
                     &sample,
                     &mut pressure_state,
                 );
@@ -175,20 +187,30 @@ fn apply_runtime_state(
     stats: &Stats,
     shared: &ProxySharedState,
     cfg: &ProxyConfig,
-    backend_available: bool,
+    runtime_support: ConntrackRuntimeSupport,
     pressure_active: bool,
 ) {
     let enabled = cfg.server.conntrack_control.inline_conntrack_control;
-    let available = enabled && backend_available && has_cap_net_admin();
-    if enabled && !available {
+    let available = effective_conntrack_enabled(cfg, runtime_support);
+    if enabled
+        && !available
+        && cfg
+            .server
+            .conntrack_control
+            .inline_conntrack_control_explicit
+    {
         warn!(
-            "conntrack control enabled but unavailable (missing CAP_NET_ADMIN or backend binaries)"
+            has_cap_net_admin = runtime_support.has_cap_net_admin,
+            backend_available = runtime_support.netfilter_backend.is_some(),
+            conntrack_binary_available = runtime_support.has_conntrack_binary,
+            configured_backend = ?cfg.server.conntrack_control.backend,
+            "conntrack control explicitly enabled but unavailable; disabling runtime features"
         );
     }
     stats.set_conntrack_control_enabled(enabled);
     stats.set_conntrack_control_available(available);
-    shared.set_conntrack_pressure_active(enabled && pressure_active);
-    stats.set_conntrack_pressure_active(enabled && pressure_active);
+    shared.set_conntrack_pressure_active(available && pressure_active);
+    stats.set_conntrack_pressure_active(available && pressure_active);
 }
 
 fn collect_pressure_sample(
@@ -228,10 +250,11 @@ fn update_pressure_state(
     stats: &Stats,
     shared: &ProxySharedState,
     cfg: &ProxyConfig,
+    effective_enabled: bool,
     sample: &PressureSample,
     state: &mut PressureState,
 ) {
-    if !cfg.server.conntrack_control.inline_conntrack_control {
+    if !effective_enabled {
         if state.active {
             state.active = false;
             state.low_streak = 0;
@@ -285,22 +308,26 @@ fn update_pressure_state(
     state.low_streak = 0;
 }
 
-async fn reconcile_rules(cfg: &ProxyConfig, backend: Option<NetfilterBackend>, stats: &Stats) {
+async fn reconcile_rules(
+    cfg: &ProxyConfig,
+    runtime_support: ConntrackRuntimeSupport,
+    stats: &Stats,
+) {
     if !cfg.server.conntrack_control.inline_conntrack_control {
         clear_notrack_rules_all_backends().await;
         stats.set_conntrack_rule_apply_ok(true);
         return;
     }
 
-    if !has_cap_net_admin() {
+    if !effective_conntrack_enabled(cfg, runtime_support) {
+        clear_notrack_rules_all_backends().await;
         stats.set_conntrack_rule_apply_ok(false);
         return;
     }
 
-    let Some(backend) = backend else {
-        stats.set_conntrack_rule_apply_ok(false);
-        return;
-    };
+    let backend = runtime_support
+        .netfilter_backend
+        .expect("netfilter backend must be available for effective conntrack control");
 
     let apply_result = match backend {
         NetfilterBackend::Nftables => apply_nft_rules(cfg).await,
@@ -315,6 +342,24 @@ async fn reconcile_rules(cfg: &ProxyConfig, backend: Option<NetfilterBackend>, s
     }
 }
 
+fn probe_runtime_support(configured_backend: ConntrackBackend) -> ConntrackRuntimeSupport {
+    ConntrackRuntimeSupport {
+        netfilter_backend: pick_backend(configured_backend),
+        has_cap_net_admin: has_cap_net_admin(),
+        has_conntrack_binary: command_exists("conntrack"),
+    }
+}
+
+fn effective_conntrack_enabled(
+    cfg: &ProxyConfig,
+    runtime_support: ConntrackRuntimeSupport,
+) -> bool {
+    cfg.server.conntrack_control.inline_conntrack_control
+        && runtime_support.has_cap_net_admin
+        && runtime_support.netfilter_backend.is_some()
+        && runtime_support.has_conntrack_binary
+}
+
 fn pick_backend(configured: ConntrackBackend) -> Option<NetfilterBackend> {
     match configured {
         ConntrackBackend::Auto => {
@@ -710,7 +755,7 @@ mod tests {
             me_queue_pressure_delta: 0,
         };
 
-        update_pressure_state(&stats, shared.as_ref(), &cfg, &sample, &mut state);
+        update_pressure_state(&stats, shared.as_ref(), &cfg, true, &sample, &mut state);
 
         assert!(state.active);
         assert!(shared.conntrack_pressure_active());
@@ -731,7 +776,14 @@ mod tests {
             accept_timeout_delta: 0,
             me_queue_pressure_delta: 0,
         };
-        update_pressure_state(&stats, shared.as_ref(), &cfg, &high_sample, &mut state);
+        update_pressure_state(
+            &stats,
+            shared.as_ref(),
+            &cfg,
+            true,
+            &high_sample,
+            &mut state,
+        );
         assert!(state.active);
 
         let low_sample = PressureSample {
@@ -740,11 +792,11 @@ mod tests {
             accept_timeout_delta: 0,
             me_queue_pressure_delta: 0,
         };
-        update_pressure_state(&stats, shared.as_ref(), &cfg, &low_sample, &mut state);
+        update_pressure_state(&stats, shared.as_ref(), &cfg, true, &low_sample, &mut state);
         assert!(state.active);
-        update_pressure_state(&stats, shared.as_ref(), &cfg, &low_sample, &mut state);
+        update_pressure_state(&stats, shared.as_ref(), &cfg, true, &low_sample, &mut state);
         assert!(state.active);
-        update_pressure_state(&stats, shared.as_ref(), &cfg, &low_sample, &mut state);
+        update_pressure_state(&stats, shared.as_ref(), &cfg, true, &low_sample, &mut state);
 
         assert!(!state.active);
         assert!(!shared.conntrack_pressure_active());
@@ -765,7 +817,7 @@ mod tests {
             me_queue_pressure_delta: 10,
         };
 
-        update_pressure_state(&stats, shared.as_ref(), &cfg, &sample, &mut state);
+        update_pressure_state(&stats, shared.as_ref(), &cfg, false, &sample, &mut state);
 
         assert!(!state.active);
         assert!(!shared.conntrack_pressure_active());

src/daemon/mod.rs

@@ -8,8 +8,8 @@ use std::io::{self, Read, Write};
 use std::os::unix::fs::OpenOptionsExt;
 use std::path::{Path, PathBuf};
 
-use nix::fcntl::{Flock, FlockArg};
 use nix::errno::Errno;
+use nix::fcntl::{Flock, FlockArg};
 use nix::unistd::{self, ForkResult, Gid, Pid, Uid, chdir, close, fork, getpid, setsid};
 use tracing::{debug, info, warn};
 
@@ -158,15 +158,15 @@ fn redirect_stdio_to_devnull() -> Result<(), DaemonError> {
     unsafe {
         // Redirect stdin (fd 0)
         if libc::dup2(devnull_fd, 0) < 0 {
-            return Err(DaemonError::RedirectFailed(nix::errno::Errno::last()));
+            return Err(DaemonError::RedirectFailed(Errno::last()));
         }
         // Redirect stdout (fd 1)
         if libc::dup2(devnull_fd, 1) < 0 {
-            return Err(DaemonError::RedirectFailed(nix::errno::Errno::last()));
+            return Err(DaemonError::RedirectFailed(Errno::last()));
         }
         // Redirect stderr (fd 2)
         if libc::dup2(devnull_fd, 2) < 0 {
-            return Err(DaemonError::RedirectFailed(nix::errno::Errno::last()));
+            return Err(DaemonError::RedirectFailed(Errno::last()));
         }
     }
 
@@ -350,11 +350,7 @@ fn set_supplementary_groups(gid: Gid) -> Result<(), nix::Error> {
                 groups.as_ptr(),
             )
         };
-        if rc == 0 {
-            Ok(())
-        } else {
-            Err(Errno::last())
-        }
+        if rc == 0 { Ok(()) } else { Err(Errno::last()) }
     }
 
     #[cfg(not(target_os = "macos"))]

src/healthcheck.rs

@@ -0,0 +1,211 @@
+use std::io::{Read, Write};
+use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr, TcpStream};
+use std::time::Duration;
+
+use serde_json::Value;
+
+use crate::config::ProxyConfig;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum HealthcheckMode {
+    Liveness,
+    Ready,
+}
+
+impl HealthcheckMode {
+    pub(crate) fn from_cli_arg(value: &str) -> Option<Self> {
+        match value {
+            "liveness" => Some(Self::Liveness),
+            "ready" => Some(Self::Ready),
+            _ => None,
+        }
+    }
+
+    fn request_path(self) -> &'static str {
+        match self {
+            Self::Liveness => "/v1/health",
+            Self::Ready => "/v1/health/ready",
+        }
+    }
+}
+
+pub(crate) fn run(config_path: &str, mode: HealthcheckMode) -> i32 {
+    match run_inner(config_path, mode) {
+        Ok(()) => 0,
+        Err(error) => {
+            eprintln!("[telemt] healthcheck failed: {error}");
+            1
+        }
+    }
+}
+
+fn run_inner(config_path: &str, mode: HealthcheckMode) -> Result<(), String> {
+    let config =
+        ProxyConfig::load(config_path).map_err(|error| format!("config load failed: {error}"))?;
+    let api_cfg = &config.server.api;
+    if !api_cfg.enabled {
+        return Ok(());
+    }
+
+    let listen: SocketAddr = api_cfg
+        .listen
+        .parse()
+        .map_err(|_| format!("invalid API listen address: {}", api_cfg.listen))?;
+    if listen.port() == 0 {
+        return Err("API listen port is 0".to_string());
+    }
+    let target = probe_target(listen);
+
+    let mut stream = TcpStream::connect_timeout(&target, Duration::from_secs(2))
+        .map_err(|error| format!("connect {target} failed: {error}"))?;
+    stream
+        .set_read_timeout(Some(Duration::from_secs(2)))
+        .map_err(|error| format!("set read timeout failed: {error}"))?;
+    stream
+        .set_write_timeout(Some(Duration::from_secs(2)))
+        .map_err(|error| format!("set write timeout failed: {error}"))?;
+
+    let request = build_request(target, mode.request_path(), &api_cfg.auth_header);
+    stream
+        .write_all(request.as_bytes())
+        .map_err(|error| format!("request write failed: {error}"))?;
+    stream
+        .flush()
+        .map_err(|error| format!("request flush failed: {error}"))?;
+
+    let mut raw_response = Vec::new();
+    stream
+        .read_to_end(&mut raw_response)
+        .map_err(|error| format!("response read failed: {error}"))?;
+    let response =
+        String::from_utf8(raw_response).map_err(|_| "response is not valid UTF-8".to_string())?;
+
+    let (status_code, body) = split_response(&response)?;
+    if status_code != 200 {
+        return Err(format!("HTTP status {status_code}"));
+    }
+
+    validate_payload(mode, body)?;
+    Ok(())
+}
+
+fn probe_target(listen: SocketAddr) -> SocketAddr {
+    match listen {
+        SocketAddr::V4(addr) => {
+            let ip = if addr.ip().is_unspecified() {
+                Ipv4Addr::LOCALHOST
+            } else {
+                *addr.ip()
+            };
+            SocketAddr::from((ip, addr.port()))
+        }
+        SocketAddr::V6(addr) => {
+            let ip = if addr.ip().is_unspecified() {
+                Ipv6Addr::LOCALHOST
+            } else {
+                *addr.ip()
+            };
+            SocketAddr::from((ip, addr.port()))
+        }
+    }
+}
+
+fn build_request(target: SocketAddr, path: &str, auth_header: &str) -> String {
+    let mut request = format!(
+        "GET {path} HTTP/1.1\r\nHost: {}\r\nConnection: close\r\n",
+        target
+    );
+    if !auth_header.is_empty() {
+        request.push_str("Authorization: ");
+        request.push_str(auth_header);
+        request.push_str("\r\n");
+    }
+    request.push_str("\r\n");
+    request
+}
+
+fn split_response(response: &str) -> Result<(u16, &str), String> {
+    let header_end = response
+        .find("\r\n\r\n")
+        .ok_or_else(|| "invalid HTTP response headers".to_string())?;
+    let header = &response[..header_end];
+    let body = &response[header_end + 4..];
+    let status_line = header
+        .lines()
+        .next()
+        .ok_or_else(|| "missing HTTP status line".to_string())?;
+    let status_code = parse_status_code(status_line)?;
+    Ok((status_code, body))
+}
+
+fn parse_status_code(status_line: &str) -> Result<u16, String> {
+    let mut parts = status_line.split_whitespace();
+    let version = parts
+        .next()
+        .ok_or_else(|| "missing HTTP version".to_string())?;
+    if !version.starts_with("HTTP/") {
+        return Err(format!("invalid HTTP status line: {status_line}"));
+    }
+    let code = parts
+        .next()
+        .ok_or_else(|| "missing HTTP status code".to_string())?;
+    code.parse::<u16>()
+        .map_err(|_| format!("invalid HTTP status code: {code}"))
+}
+
+fn validate_payload(mode: HealthcheckMode, body: &str) -> Result<(), String> {
+    let payload: Value =
+        serde_json::from_str(body).map_err(|_| "response body is not valid JSON".to_string())?;
+    if payload.get("ok").and_then(Value::as_bool) != Some(true) {
+        return Err("response JSON has ok=false".to_string());
+    }
+
+    let data = payload
+        .get("data")
+        .ok_or_else(|| "response JSON has no data field".to_string())?;
+    match mode {
+        HealthcheckMode::Liveness => {
+            if data.get("status").and_then(Value::as_str) != Some("ok") {
+                return Err("liveness status is not ok".to_string());
+            }
+        }
+        HealthcheckMode::Ready => {
+            if data.get("ready").and_then(Value::as_bool) != Some(true) {
+                return Err("readiness flag is false".to_string());
+            }
+        }
+    }
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{HealthcheckMode, parse_status_code, split_response, validate_payload};
+
+    #[test]
+    fn parse_status_code_reads_http_200() {
+        let status = parse_status_code("HTTP/1.1 200 OK").expect("must parse status");
+        assert_eq!(status, 200);
+    }
+
+    #[test]
+    fn split_response_extracts_status_and_body() {
+        let response = "HTTP/1.1 200 OK\r\nContent-Type: application/json\r\n\r\n{\"ok\":true}";
+        let (status, body) = split_response(response).expect("must split response");
+        assert_eq!(status, 200);
+        assert_eq!(body, "{\"ok\":true}");
+    }
+
+    #[test]
+    fn validate_payload_accepts_liveness_contract() {
+        let body = "{\"ok\":true,\"data\":{\"status\":\"ok\"}}";
+        validate_payload(HealthcheckMode::Liveness, body).expect("liveness payload must pass");
+    }
+
+    #[test]
+    fn validate_payload_rejects_not_ready() {
+        let body = "{\"ok\":true,\"data\":{\"ready\":false}}";
+        let result = validate_payload(HealthcheckMode::Ready, body);
+        assert!(result.is_err());
+    }
+}

src/maestro/runtime_tasks.rs

@@ -190,8 +190,16 @@ pub(crate) async fn spawn_runtime_tasks(
     );
     let mut config_rx_rate_limits = config_rx.clone();
     tokio::spawn(async move {
-        let mut prev_user_limits = config_rx_rate_limits.borrow().access.user_rate_limits.clone();
-        let mut prev_cidr_limits = config_rx_rate_limits.borrow().access.cidr_rate_limits.clone();
+        let mut prev_user_limits = config_rx_rate_limits
+            .borrow()
+            .access
+            .user_rate_limits
+            .clone();
+        let mut prev_cidr_limits = config_rx_rate_limits
+            .borrow()
+            .access
+            .cidr_rate_limits
+            .clone();
         loop {
             if config_rx_rate_limits.changed().await.is_err() {
                 break;

src/main.rs

@@ -8,6 +8,7 @@ mod crypto;
 #[cfg(unix)]
 mod daemon;
 mod error;
+mod healthcheck;
 mod ip_tracker;
 #[cfg(test)]
 #[path = "tests/ip_tracker_encapsulation_adversarial_tests.rs"]

src/metrics.rs

@@ -1310,6 +1310,143 @@ async fn render_metrics(
             0
         }
     );
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_fair_pressure_state Worker-local fairness pressure state"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_fair_pressure_state gauge");
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_pressure_state {}",
+        if me_allows_normal {
+            stats.get_me_fair_pressure_state_gauge()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_fair_active_flows Fair-scheduler active flow count"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_fair_active_flows gauge");
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_active_flows {}",
+        if me_allows_normal {
+            stats.get_me_fair_active_flows_gauge()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_fair_queued_bytes Fair-scheduler queued bytes"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_fair_queued_bytes gauge");
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_queued_bytes {}",
+        if me_allows_normal {
+            stats.get_me_fair_queued_bytes_gauge()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_fair_flow_state_gauge Fair-scheduler flow health classes"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_fair_flow_state_gauge gauge");
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_flow_state_gauge{{class=\"standing\"}} {}",
+        if me_allows_normal {
+            stats.get_me_fair_standing_flows_gauge()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_flow_state_gauge{{class=\"backpressured\"}} {}",
+        if me_allows_normal {
+            stats.get_me_fair_backpressured_flows_gauge()
+        } else {
+            0
+        }
+    );
+
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_fair_events_total Fair-scheduler event counters"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_fair_events_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_events_total{{event=\"scheduler_round\"}} {}",
+        if me_allows_normal {
+            stats.get_me_fair_scheduler_rounds_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_events_total{{event=\"deficit_grant\"}} {}",
+        if me_allows_normal {
+            stats.get_me_fair_deficit_grants_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_events_total{{event=\"deficit_skip\"}} {}",
+        if me_allows_normal {
+            stats.get_me_fair_deficit_skips_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_events_total{{event=\"enqueue_reject\"}} {}",
+        if me_allows_normal {
+            stats.get_me_fair_enqueue_rejects_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_events_total{{event=\"shed_drop\"}} {}",
+        if me_allows_normal {
+            stats.get_me_fair_shed_drops_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_events_total{{event=\"penalty\"}} {}",
+        if me_allows_normal {
+            stats.get_me_fair_penalties_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_fair_events_total{{event=\"downstream_stall\"}} {}",
+        if me_allows_normal {
+            stats.get_me_fair_downstream_stalls_total()
+        } else {
+            0
+        }
+    );
 
     let _ = writeln!(
         out,

src/proxy/direct_relay.rs

@@ -316,7 +316,9 @@ where
 
     stats.increment_user_connects(user);
     let _direct_connection_lease = stats.acquire_direct_connection_lease();
-    let traffic_lease = shared.traffic_limiter.acquire_lease(user, success.peer.ip());
+    let traffic_lease = shared
+        .traffic_limiter
+        .acquire_lease(user, success.peer.ip());
 
     let buffer_pool_trim = Arc::clone(&buffer_pool);
     let relay_activity_timeout = if shared.conntrack_pressure_active() {

src/proxy/relay.rs

@@ -289,17 +289,9 @@ impl<S> StatsIo<S> {
         let Some(started_at) = wait.started_at.take() else {
             return;
         };
-        let wait_ms = started_at
-            .elapsed()
-            .as_millis()
-            .min(u128::from(u64::MAX)) as u64;
+        let wait_ms = started_at.elapsed().as_millis().min(u128::from(u64::MAX)) as u64;
         if let Some(lease) = lease {
-            lease.observe_wait_ms(
-                direction,
-                wait.blocked_user,
-                wait.blocked_cidr,
-                wait_ms,
-            );
+            lease.observe_wait_ms(direction, wait.blocked_user, wait.blocked_cidr, wait_ms);
         }
         wait.blocked_user = false;
         wait.blocked_cidr = false;
@@ -340,8 +332,7 @@ impl<S> StatsIo<S> {
         while self.c2s_rate_debt_bytes > 0 {
             let consume = lease.try_consume(RateDirection::Up, self.c2s_rate_debt_bytes);
             if consume.granted > 0 {
-                self.c2s_rate_debt_bytes =
-                    self.c2s_rate_debt_bytes.saturating_sub(consume.granted);
+                self.c2s_rate_debt_bytes = self.c2s_rate_debt_bytes.saturating_sub(consume.granted);
                 continue;
             }
             Self::arm_wait(
@@ -647,7 +638,10 @@ impl<S: AsyncWrite + Unpin> AsyncWrite for StatsIo<S> {
         match Pin::new(&mut this.inner).poll_write(cx, write_buf) {
             Poll::Ready(Ok(n)) => {
                 if reserved_bytes > n as u64 {
-                    refund_reserved_quota_bytes(this.user_stats.as_ref(), reserved_bytes - n as u64);
+                    refund_reserved_quota_bytes(
+                        this.user_stats.as_ref(),
+                        reserved_bytes - n as u64,
+                    );
                 }
                 if shaper_reserved_bytes > n as u64
                     && let Some(lease) = this.traffic_lease.as_ref()

src/proxy/traffic_limiter.rs

@@ -74,7 +74,8 @@ impl ScopeMetrics {
                 self.wait_up_ms_total.fetch_add(wait_ms, Ordering::Relaxed);
             }
             RateDirection::Down => {
-                self.wait_down_ms_total.fetch_add(wait_ms, Ordering::Relaxed);
+                self.wait_down_ms_total
+                    .fetch_add(wait_ms, Ordering::Relaxed);
             }
         }
     }
@@ -254,9 +255,7 @@ impl CidrDirectionBucket {
             let grant = if guaranteed_remaining > 0 {
                 requested.min(guaranteed_remaining).min(total_remaining)
             } else {
-                requested
-                    .min(total_remaining)
-                    .min(MAX_BORROW_CHUNK_BYTES)
+                requested.min(total_remaining).min(MAX_BORROW_CHUNK_BYTES)
             };
 
             if grant == 0 {
@@ -266,12 +265,7 @@ impl CidrDirectionBucket {
             let next_total = total_used.saturating_add(grant);
             if self
                 .used
-                .compare_exchange_weak(
-                    total_used,
-                    next_total,
-                    Ordering::Relaxed,
-                    Ordering::Relaxed,
-                )
+                .compare_exchange_weak(total_used, next_total, Ordering::Relaxed, Ordering::Relaxed)
                 .is_ok()
             {
                 user_state.used.fetch_add(grant, Ordering::Relaxed);
@@ -430,8 +424,14 @@ struct PolicySnapshot {
 impl PolicySnapshot {
     fn match_cidr(&self, ip: IpAddr) -> Option<&CidrRule> {
         match ip {
-            IpAddr::V4(_) => self.cidr_rules_v4.iter().find(|rule| rule.cidr.contains(ip)),
-            IpAddr::V6(_) => self.cidr_rules_v6.iter().find(|rule| rule.cidr.contains(ip)),
+            IpAddr::V4(_) => self
+                .cidr_rules_v4
+                .iter()
+                .find(|rule| rule.cidr.contains(ip)),
+            IpAddr::V6(_) => self
+                .cidr_rules_v6
+                .iter()
+                .find(|rule| rule.cidr.contains(ip)),
         }
     }
 }
@@ -535,7 +535,8 @@ impl TrafficLease {
         if let (Some(cidr_bucket), Some(cidr_user_share)) =
             (self.cidr_bucket.as_ref(), self.cidr_user_share.as_ref())
         {
-            let cidr_granted = cidr_bucket.try_consume_for_user(direction, cidr_user_share, granted);
+            let cidr_granted =
+                cidr_bucket.try_consume_for_user(direction, cidr_user_share, granted);
             if cidr_granted < granted
                 && let Some(user_bucket) = self.user_bucket.as_ref()
             {
@@ -693,7 +694,9 @@ impl TrafficLimiter {
                 .get_or_insert_with(user, || UserBucket::new(limit));
             bucket.set_rates(limit);
             bucket.active_leases.fetch_add(1, Ordering::Relaxed);
-            self.user_scope.active_leases.fetch_add(1, Ordering::Relaxed);
+            self.user_scope
+                .active_leases
+                .fetch_add(1, Ordering::Relaxed);
             user_bucket = Some(bucket);
         }
 
@@ -706,7 +709,9 @@ impl TrafficLimiter {
                 .get_or_insert_with(rule.key.as_str(), || CidrBucket::new(rule.limits));
             bucket.set_rates(rule.limits);
             bucket.active_leases.fetch_add(1, Ordering::Relaxed);
-            self.cidr_scope.active_leases.fetch_add(1, Ordering::Relaxed);
+            self.cidr_scope
+                .active_leases
+                .fetch_add(1, Ordering::Relaxed);
             let share = bucket.acquire_user_share(user);
             cidr_user_key = Some(user.to_string());
             cidr_user_share = Some(share);
@@ -784,7 +789,8 @@ impl TrafficLimiter {
 
         let policy = self.policy.load_full();
         self.user_buckets.retain(|user, bucket| {
-            bucket.active_leases.load(Ordering::Relaxed) > 0 || policy.user_limits.contains_key(user)
+            bucket.active_leases.load(Ordering::Relaxed) > 0
+                || policy.user_limits.contains_key(user)
         });
         self.cidr_buckets.retain(|cidr_key, bucket| {
             bucket.cleanup_idle_users();

src/stats/mod.rs

@@ -175,6 +175,18 @@ pub struct Stats {
     me_route_drop_queue_full: AtomicU64,
     me_route_drop_queue_full_base: AtomicU64,
     me_route_drop_queue_full_high: AtomicU64,
+    me_fair_pressure_state_gauge: AtomicU64,
+    me_fair_active_flows_gauge: AtomicU64,
+    me_fair_queued_bytes_gauge: AtomicU64,
+    me_fair_standing_flows_gauge: AtomicU64,
+    me_fair_backpressured_flows_gauge: AtomicU64,
+    me_fair_scheduler_rounds_total: AtomicU64,
+    me_fair_deficit_grants_total: AtomicU64,
+    me_fair_deficit_skips_total: AtomicU64,
+    me_fair_enqueue_rejects_total: AtomicU64,
+    me_fair_shed_drops_total: AtomicU64,
+    me_fair_penalties_total: AtomicU64,
+    me_fair_downstream_stalls_total: AtomicU64,
     me_d2c_batches_total: AtomicU64,
     me_d2c_batch_frames_total: AtomicU64,
     me_d2c_batch_bytes_total: AtomicU64,
@@ -856,6 +868,78 @@ impl Stats {
                 .fetch_add(1, Ordering::Relaxed);
         }
     }
+    pub fn set_me_fair_pressure_state_gauge(&self, value: u64) {
+        if self.telemetry_me_allows_normal() {
+            self.me_fair_pressure_state_gauge
+                .store(value, Ordering::Relaxed);
+        }
+    }
+    pub fn set_me_fair_active_flows_gauge(&self, value: u64) {
+        if self.telemetry_me_allows_normal() {
+            self.me_fair_active_flows_gauge
+                .store(value, Ordering::Relaxed);
+        }
+    }
+    pub fn set_me_fair_queued_bytes_gauge(&self, value: u64) {
+        if self.telemetry_me_allows_normal() {
+            self.me_fair_queued_bytes_gauge
+                .store(value, Ordering::Relaxed);
+        }
+    }
+    pub fn set_me_fair_standing_flows_gauge(&self, value: u64) {
+        if self.telemetry_me_allows_normal() {
+            self.me_fair_standing_flows_gauge
+                .store(value, Ordering::Relaxed);
+        }
+    }
+    pub fn set_me_fair_backpressured_flows_gauge(&self, value: u64) {
+        if self.telemetry_me_allows_normal() {
+            self.me_fair_backpressured_flows_gauge
+                .store(value, Ordering::Relaxed);
+        }
+    }
+    pub fn add_me_fair_scheduler_rounds_total(&self, value: u64) {
+        if self.telemetry_me_allows_normal() && value > 0 {
+            self.me_fair_scheduler_rounds_total
+                .fetch_add(value, Ordering::Relaxed);
+        }
+    }
+    pub fn add_me_fair_deficit_grants_total(&self, value: u64) {
+        if self.telemetry_me_allows_normal() && value > 0 {
+            self.me_fair_deficit_grants_total
+                .fetch_add(value, Ordering::Relaxed);
+        }
+    }
+    pub fn add_me_fair_deficit_skips_total(&self, value: u64) {
+        if self.telemetry_me_allows_normal() && value > 0 {
+            self.me_fair_deficit_skips_total
+                .fetch_add(value, Ordering::Relaxed);
+        }
+    }
+    pub fn add_me_fair_enqueue_rejects_total(&self, value: u64) {
+        if self.telemetry_me_allows_normal() && value > 0 {
+            self.me_fair_enqueue_rejects_total
+                .fetch_add(value, Ordering::Relaxed);
+        }
+    }
+    pub fn add_me_fair_shed_drops_total(&self, value: u64) {
+        if self.telemetry_me_allows_normal() && value > 0 {
+            self.me_fair_shed_drops_total
+                .fetch_add(value, Ordering::Relaxed);
+        }
+    }
+    pub fn add_me_fair_penalties_total(&self, value: u64) {
+        if self.telemetry_me_allows_normal() && value > 0 {
+            self.me_fair_penalties_total
+                .fetch_add(value, Ordering::Relaxed);
+        }
+    }
+    pub fn add_me_fair_downstream_stalls_total(&self, value: u64) {
+        if self.telemetry_me_allows_normal() && value > 0 {
+            self.me_fair_downstream_stalls_total
+                .fetch_add(value, Ordering::Relaxed);
+        }
+    }
     pub fn increment_me_d2c_batches_total(&self) {
         if self.telemetry_me_allows_normal() {
             self.me_d2c_batches_total.fetch_add(1, Ordering::Relaxed);
@@ -1806,6 +1890,43 @@ impl Stats {
     pub fn get_me_route_drop_queue_full_high(&self) -> u64 {
         self.me_route_drop_queue_full_high.load(Ordering::Relaxed)
     }
+    pub fn get_me_fair_pressure_state_gauge(&self) -> u64 {
+        self.me_fair_pressure_state_gauge.load(Ordering::Relaxed)
+    }
+    pub fn get_me_fair_active_flows_gauge(&self) -> u64 {
+        self.me_fair_active_flows_gauge.load(Ordering::Relaxed)
+    }
+    pub fn get_me_fair_queued_bytes_gauge(&self) -> u64 {
+        self.me_fair_queued_bytes_gauge.load(Ordering::Relaxed)
+    }
+    pub fn get_me_fair_standing_flows_gauge(&self) -> u64 {
+        self.me_fair_standing_flows_gauge.load(Ordering::Relaxed)
+    }
+    pub fn get_me_fair_backpressured_flows_gauge(&self) -> u64 {
+        self.me_fair_backpressured_flows_gauge
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_fair_scheduler_rounds_total(&self) -> u64 {
+        self.me_fair_scheduler_rounds_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_fair_deficit_grants_total(&self) -> u64 {
+        self.me_fair_deficit_grants_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_fair_deficit_skips_total(&self) -> u64 {
+        self.me_fair_deficit_skips_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_fair_enqueue_rejects_total(&self) -> u64 {
+        self.me_fair_enqueue_rejects_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_fair_shed_drops_total(&self) -> u64 {
+        self.me_fair_shed_drops_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_fair_penalties_total(&self) -> u64 {
+        self.me_fair_penalties_total.load(Ordering::Relaxed)
+    }
+    pub fn get_me_fair_downstream_stalls_total(&self) -> u64 {
+        self.me_fair_downstream_stalls_total.load(Ordering::Relaxed)
+    }
     pub fn get_me_d2c_batches_total(&self) -> u64 {
         self.me_d2c_batches_total.load(Ordering::Relaxed)
     }

src/tls_front/emulator.rs

@@ -66,9 +66,19 @@ fn ensure_payload_capacity(mut sizes: Vec<usize>, payload_len: usize) -> Vec<usi
 fn emulated_app_data_sizes(cached: &CachedTlsData) -> Vec<usize> {
     match cached.behavior_profile.source {
         TlsProfileSource::Raw | TlsProfileSource::Merged => {
-            if !cached.behavior_profile.app_data_record_sizes.is_empty() {
-                return cached.behavior_profile.app_data_record_sizes.clone();
-            }
+            return cached
+                .app_data_records_sizes
+                .first()
+                .copied()
+                .or_else(|| {
+                    cached
+                        .behavior_profile
+                        .app_data_record_sizes
+                        .first()
+                        .copied()
+                })
+                .map(|size| vec![size])
+                .unwrap_or_else(|| vec![cached.total_app_data_len.max(1024)]);
         }
         TlsProfileSource::Default | TlsProfileSource::Rustls => {}
     }
@@ -80,8 +90,8 @@ fn emulated_app_data_sizes(cached: &CachedTlsData) -> Vec<usize> {
     sizes
 }
 
-fn emulated_change_cipher_spec_count(cached: &CachedTlsData) -> usize {
-    usize::from(cached.behavior_profile.change_cipher_spec_count.max(1))
+fn emulated_change_cipher_spec_count(_cached: &CachedTlsData) -> usize {
+    1
 }
 
 fn emulated_ticket_record_sizes(
@@ -89,17 +99,20 @@ fn emulated_ticket_record_sizes(
     new_session_tickets: u8,
     rng: &SecureRandom,
 ) -> Vec<usize> {
-    let mut sizes = match cached.behavior_profile.source {
+    let target_count = usize::from(new_session_tickets.min(MAX_TICKET_RECORDS as u8));
+    if target_count == 0 {
+        return Vec::new();
+    }
+
+    let profiled_sizes = match cached.behavior_profile.source {
         TlsProfileSource::Raw | TlsProfileSource::Merged => {
-            cached.behavior_profile.ticket_record_sizes.clone()
+            cached.behavior_profile.ticket_record_sizes.as_slice()
         }
-        TlsProfileSource::Default | TlsProfileSource::Rustls => Vec::new(),
+        TlsProfileSource::Default | TlsProfileSource::Rustls => &[],
     };
 
-    let target_count = sizes
-        .len()
-        .max(usize::from(new_session_tickets.min(MAX_TICKET_RECORDS as u8)))
-        .min(MAX_TICKET_RECORDS);
+    let mut sizes = Vec::with_capacity(target_count);
+    sizes.extend(profiled_sizes.iter().copied().take(target_count));
 
     while sizes.len() < target_count {
         sizes.push(rng.range(48) + 48);
@@ -240,7 +253,18 @@ pub fn build_emulated_server_hello(
     }
 
     // --- ApplicationData (fake encrypted records) ---
-    let mut sizes = jitter_and_clamp_sizes(&emulated_app_data_sizes(cached), rng);
+    let mut sizes = {
+        let base_sizes = emulated_app_data_sizes(cached);
+        match cached.behavior_profile.source {
+            TlsProfileSource::Raw | TlsProfileSource::Merged => base_sizes
+                .into_iter()
+                .map(|size| size.clamp(MIN_APP_DATA, MAX_APP_DATA))
+                .collect(),
+            TlsProfileSource::Default | TlsProfileSource::Rustls => {
+                jitter_and_clamp_sizes(&base_sizes, rng)
+            }
+        }
+    };
     let compact_payload = cached
         .cert_info
         .as_ref()
@@ -329,11 +353,11 @@ pub fn build_emulated_server_hello(
     let mut tickets = Vec::new();
     for ticket_len in emulated_ticket_record_sizes(cached, new_session_tickets, rng) {
         let mut rec = Vec::with_capacity(5 + ticket_len);
-            rec.push(TLS_RECORD_APPLICATION);
-            rec.extend_from_slice(&TLS_VERSION);
-            rec.extend_from_slice(&(ticket_len as u16).to_be_bytes());
-            rec.extend_from_slice(&rng.bytes(ticket_len));
-            tickets.extend_from_slice(&rec);
+        rec.push(TLS_RECORD_APPLICATION);
+        rec.extend_from_slice(&TLS_VERSION);
+        rec.extend_from_slice(&(ticket_len as u16).to_be_bytes());
+        rec.extend_from_slice(&rng.bytes(ticket_len));
+        tickets.extend_from_slice(&rec);
     }
 
     let mut response = Vec::with_capacity(
@@ -506,7 +530,7 @@ mod tests {
     }
 
     #[test]
-    fn test_build_emulated_server_hello_replays_tail_records_for_profiled_tls() {
+    fn test_build_emulated_server_hello_ignores_tail_records_for_profiled_tls() {
         let mut cached = make_cached(None);
         cached.app_data_records_sizes = vec![27, 3905, 537, 69];
         cached.total_app_data_len = 4538;
@@ -528,19 +552,11 @@ mod tests {
 
         let hello_len = u16::from_be_bytes([response[3], response[4]]) as usize;
         let ccs_start = 5 + hello_len;
-        let mut pos = ccs_start + 6;
-        let mut app_lengths = Vec::new();
-        while pos + 5 <= response.len() {
-            assert_eq!(response[pos], TLS_RECORD_APPLICATION);
-            let record_len = u16::from_be_bytes([response[pos + 3], response[pos + 4]]) as usize;
-            app_lengths.push(record_len);
-            pos += 5 + record_len;
-        }
-
-        assert_eq!(app_lengths.len(), 4);
-        assert_eq!(app_lengths[0], 64);
-        assert_eq!(app_lengths[3], 69);
-        assert!(app_lengths[1] >= 64);
-        assert!(app_lengths[2] >= 64);
+        let app_start = ccs_start + 6;
+        let app_len =
+            u16::from_be_bytes([response[app_start + 3], response[app_start + 4]]) as usize;
+        assert_eq!(response[app_start], TLS_RECORD_APPLICATION);
+        assert_eq!(app_len, 64);
+        assert_eq!(app_start + 5 + app_len, response.len());
     }
 }

src/tls_front/fetcher.rs

@@ -1,6 +1,7 @@
 #![allow(clippy::too_many_arguments)]
 
 use dashmap::DashMap;
+use std::net::SocketAddr;
 use std::sync::Arc;
 use std::sync::OnceLock;
 use std::time::{Duration, Instant};
@@ -793,6 +794,51 @@ async fn connect_tcp_with_upstream(
     ))
 }
 
+fn socket_addrs_from_upstream_stream(
+    stream: &UpstreamStream,
+) -> (Option<SocketAddr>, Option<SocketAddr>) {
+    match stream {
+        UpstreamStream::Tcp(tcp) => (tcp.local_addr().ok(), tcp.peer_addr().ok()),
+        UpstreamStream::Shadowsocks(_) => (None, None),
+    }
+}
+
+fn build_tls_fetch_proxy_header(
+    proxy_protocol: u8,
+    src_addr: Option<SocketAddr>,
+    dst_addr: Option<SocketAddr>,
+) -> Option<Vec<u8>> {
+    match proxy_protocol {
+        0 => None,
+        2 => {
+            let header = match (src_addr, dst_addr) {
+                (Some(src @ SocketAddr::V4(_)), Some(dst @ SocketAddr::V4(_)))
+                | (Some(src @ SocketAddr::V6(_)), Some(dst @ SocketAddr::V6(_))) => {
+                    ProxyProtocolV2Builder::new().with_addrs(src, dst).build()
+                }
+                _ => ProxyProtocolV2Builder::new().build(),
+            };
+            Some(header)
+        }
+        _ => {
+            let header = match (src_addr, dst_addr) {
+                (Some(SocketAddr::V4(src)), Some(SocketAddr::V4(dst))) => {
+                    ProxyProtocolV1Builder::new()
+                        .tcp4(src.into(), dst.into())
+                        .build()
+                }
+                (Some(SocketAddr::V6(src)), Some(SocketAddr::V6(dst))) => {
+                    ProxyProtocolV1Builder::new()
+                        .tcp6(src.into(), dst.into())
+                        .build()
+                }
+                _ => ProxyProtocolV1Builder::new().build(),
+            };
+            Some(header)
+        }
+    }
+}
+
 fn encode_tls13_certificate_message(cert_chain_der: &[Vec<u8>]) -> Option<Vec<u8>> {
     if cert_chain_der.is_empty() {
         return None;
@@ -824,7 +870,7 @@ async fn fetch_via_raw_tls_stream<S>(
     mut stream: S,
     sni: &str,
     connect_timeout: Duration,
-    proxy_protocol: u8,
+    proxy_header: Option<Vec<u8>>,
     profile: TlsFetchProfile,
     grease_enabled: bool,
     deterministic: bool,
@@ -835,11 +881,7 @@ where
     let rng = SecureRandom::new();
     let client_hello = build_client_hello(sni, &rng, profile, grease_enabled, deterministic);
     timeout(connect_timeout, async {
-        if proxy_protocol > 0 {
-            let header = match proxy_protocol {
-                2 => ProxyProtocolV2Builder::new().build(),
-                _ => ProxyProtocolV1Builder::new().build(),
-            };
+        if let Some(header) = proxy_header.as_ref() {
             stream.write_all(&header).await?;
         }
         stream.write_all(&client_hello).await?;
@@ -921,11 +963,12 @@ async fn fetch_via_raw_tls(
                     sock = %sock_path,
                     "Raw TLS fetch using mask unix socket"
                 );
+                let proxy_header = build_tls_fetch_proxy_header(proxy_protocol, None, None);
                 return fetch_via_raw_tls_stream(
                     stream,
                     sni,
                     connect_timeout,
-                    proxy_protocol,
+                    proxy_header,
                     profile,
                     grease_enabled,
                     deterministic,
@@ -956,11 +999,13 @@ async fn fetch_via_raw_tls(
     let stream =
         connect_tcp_with_upstream(host, port, connect_timeout, upstream, scope, strict_route)
             .await?;
+    let (src_addr, dst_addr) = socket_addrs_from_upstream_stream(&stream);
+    let proxy_header = build_tls_fetch_proxy_header(proxy_protocol, src_addr, dst_addr);
     fetch_via_raw_tls_stream(
         stream,
         sni,
         connect_timeout,
-        proxy_protocol,
+        proxy_header,
         profile,
         grease_enabled,
         deterministic,
@@ -972,17 +1017,13 @@ async fn fetch_via_rustls_stream<S>(
     mut stream: S,
     host: &str,
     sni: &str,
-    proxy_protocol: u8,
+    proxy_header: Option<Vec<u8>>,
 ) -> Result<TlsFetchResult>
 where
     S: AsyncRead + AsyncWrite + Unpin,
 {
     // rustls handshake path for certificate and basic negotiated metadata.
-    if proxy_protocol > 0 {
-        let header = match proxy_protocol {
-            2 => ProxyProtocolV2Builder::new().build(),
-            _ => ProxyProtocolV1Builder::new().build(),
-        };
+    if let Some(header) = proxy_header.as_ref() {
         stream.write_all(&header).await?;
         stream.flush().await?;
     }
@@ -1082,7 +1123,8 @@ async fn fetch_via_rustls(
                     sock = %sock_path,
                     "Rustls fetch using mask unix socket"
                 );
-                return fetch_via_rustls_stream(stream, host, sni, proxy_protocol).await;
+                let proxy_header = build_tls_fetch_proxy_header(proxy_protocol, None, None);
+                return fetch_via_rustls_stream(stream, host, sni, proxy_header).await;
             }
             Ok(Err(e)) => {
                 warn!(
@@ -1108,7 +1150,9 @@ async fn fetch_via_rustls(
     let stream =
         connect_tcp_with_upstream(host, port, connect_timeout, upstream, scope, strict_route)
             .await?;
-    fetch_via_rustls_stream(stream, host, sni, proxy_protocol).await
+    let (src_addr, dst_addr) = socket_addrs_from_upstream_stream(&stream);
+    let proxy_header = build_tls_fetch_proxy_header(proxy_protocol, src_addr, dst_addr);
+    fetch_via_rustls_stream(stream, host, sni, proxy_header).await
 }
 
 /// Fetch real TLS metadata with an adaptive multi-profile strategy.
@@ -1278,11 +1322,13 @@ pub async fn fetch_real_tls(
 
 #[cfg(test)]
 mod tests {
+    use std::net::SocketAddr;
     use std::time::{Duration, Instant};
 
     use super::{
-        ProfileCacheValue, TlsFetchStrategy, build_client_hello, derive_behavior_profile,
-        encode_tls13_certificate_message, order_profiles, profile_cache, profile_cache_key,
+        ProfileCacheValue, TlsFetchStrategy, build_client_hello, build_tls_fetch_proxy_header,
+        derive_behavior_profile, encode_tls13_certificate_message, order_profiles, profile_cache,
+        profile_cache_key,
     };
     use crate::config::TlsFetchProfile;
     use crate::crypto::SecureRandom;
@@ -1423,4 +1469,48 @@ mod tests {
 
         assert_eq!(first, second);
     }
+
+    #[test]
+    fn test_build_tls_fetch_proxy_header_v2_with_tcp_addrs() {
+        let src: SocketAddr = "198.51.100.10:42000".parse().expect("valid src");
+        let dst: SocketAddr = "203.0.113.20:443".parse().expect("valid dst");
+        let header = build_tls_fetch_proxy_header(2, Some(src), Some(dst)).expect("header");
+
+        assert_eq!(
+            &header[..12],
+            &[
+                0x0d, 0x0a, 0x0d, 0x0a, 0x00, 0x0d, 0x0a, 0x51, 0x55, 0x49, 0x54, 0x0a
+            ]
+        );
+        assert_eq!(header[12], 0x21);
+        assert_eq!(header[13], 0x11);
+        assert_eq!(u16::from_be_bytes([header[14], header[15]]), 12);
+        assert_eq!(&header[16..20], &[198, 51, 100, 10]);
+        assert_eq!(&header[20..24], &[203, 0, 113, 20]);
+        assert_eq!(u16::from_be_bytes([header[24], header[25]]), 42000);
+        assert_eq!(u16::from_be_bytes([header[26], header[27]]), 443);
+    }
+
+    #[test]
+    fn test_build_tls_fetch_proxy_header_v2_mixed_family_falls_back_to_local_command() {
+        let src: SocketAddr = "198.51.100.10:42000".parse().expect("valid src");
+        let dst: SocketAddr = "[2001:db8::20]:443".parse().expect("valid dst");
+        let header = build_tls_fetch_proxy_header(2, Some(src), Some(dst)).expect("header");
+
+        assert_eq!(header[12], 0x20);
+        assert_eq!(header[13], 0x00);
+        assert_eq!(u16::from_be_bytes([header[14], header[15]]), 0);
+    }
+
+    #[test]
+    fn test_build_tls_fetch_proxy_header_v1_with_tcp_addrs() {
+        let src: SocketAddr = "198.51.100.10:42000".parse().expect("valid src");
+        let dst: SocketAddr = "203.0.113.20:443".parse().expect("valid dst");
+        let header = build_tls_fetch_proxy_header(1, Some(src), Some(dst)).expect("header");
+
+        assert_eq!(
+            header,
+            b"PROXY TCP4 198.51.100.10 203.0.113.20 42000 443\r\n"
+        );
+    }
 }

src/tls_front/tests/emulator_profile_fidelity_security_tests.rs

@@ -52,7 +52,7 @@ fn record_lengths_by_type(response: &[u8], wanted_type: u8) -> Vec<usize> {
 }
 
 #[test]
-fn emulated_server_hello_replays_profile_change_cipher_spec_count() {
+fn emulated_server_hello_keeps_single_change_cipher_spec_for_client_compatibility() {
     let cached = make_cached();
     let rng = SecureRandom::new();
 
@@ -69,12 +69,12 @@ fn emulated_server_hello_replays_profile_change_cipher_spec_count() {
 
     assert_eq!(response[0], TLS_RECORD_HANDSHAKE);
     let ccs_records = record_lengths_by_type(&response, TLS_RECORD_CHANGE_CIPHER);
-    assert_eq!(ccs_records.len(), 2);
+    assert_eq!(ccs_records.len(), 1);
     assert!(ccs_records.iter().all(|len| *len == 1));
 }
 
 #[test]
-fn emulated_server_hello_replays_profile_ticket_tail_lengths() {
+fn emulated_server_hello_does_not_emit_profile_ticket_tail_when_disabled() {
     let cached = make_cached();
     let rng = SecureRandom::new();
 
@@ -90,6 +90,25 @@ fn emulated_server_hello_replays_profile_ticket_tail_lengths() {
     );
 
     let app_records = record_lengths_by_type(&response, TLS_RECORD_APPLICATION);
-    assert!(app_records.len() >= 4);
-    assert_eq!(&app_records[app_records.len() - 2..], &[220, 180]);
+    assert_eq!(app_records, vec![1200]);
+}
+
+#[test]
+fn emulated_server_hello_uses_profile_ticket_lengths_when_enabled() {
+    let cached = make_cached();
+    let rng = SecureRandom::new();
+
+    let response = build_emulated_server_hello(
+        b"secret",
+        &[0x91; 32],
+        &[0x92; 16],
+        &cached,
+        false,
+        &rng,
+        None,
+        2,
+    );
+
+    let app_records = record_lengths_by_type(&response, TLS_RECORD_APPLICATION);
+    assert_eq!(app_records, vec![1200, 220, 180]);
 }

src/transport/middle_proxy/fairness/mod.rs

@@ -0,0 +1,13 @@
+//! Backpressure-driven fairness control for ME reader routing.
+//!
+//! This module keeps fairness decisions worker-local:
+//! each reader loop owns one scheduler instance and mutates it without locks.
+
+mod model;
+mod pressure;
+mod scheduler;
+
+#[cfg(test)]
+pub(crate) use model::PressureState;
+pub(crate) use model::{AdmissionDecision, DispatchAction, DispatchFeedback, SchedulerDecision};
+pub(crate) use scheduler::{WorkerFairnessConfig, WorkerFairnessSnapshot, WorkerFairnessState};

src/transport/middle_proxy/fairness/model.rs

@@ -0,0 +1,140 @@
+use std::time::Instant;
+
+use bytes::Bytes;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+#[repr(u8)]
+pub(crate) enum PressureState {
+    Normal = 0,
+    Pressured = 1,
+    Shedding = 2,
+    Saturated = 3,
+}
+
+impl PressureState {
+    pub(crate) fn as_u8(self) -> u8 {
+        self as u8
+    }
+}
+
+impl Default for PressureState {
+    fn default() -> Self {
+        Self::Normal
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum FlowPressureClass {
+    Healthy,
+    Bursty,
+    Backpressured,
+    Standing,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum StandingQueueState {
+    Transient,
+    Standing,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum FlowSchedulerState {
+    Idle,
+    Active,
+    Backpressured,
+    Penalized,
+    SheddingCandidate,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct QueuedFrame {
+    pub(crate) conn_id: u64,
+    pub(crate) flags: u32,
+    pub(crate) data: Bytes,
+    pub(crate) enqueued_at: Instant,
+}
+
+impl QueuedFrame {
+    #[inline]
+    pub(crate) fn queued_bytes(&self) -> u64 {
+        self.data.len() as u64
+    }
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct FlowFairnessState {
+    pub(crate) _flow_id: u64,
+    pub(crate) _worker_id: u16,
+    pub(crate) pending_bytes: u64,
+    pub(crate) deficit_bytes: i64,
+    pub(crate) queue_started_at: Option<Instant>,
+    pub(crate) last_drain_at: Option<Instant>,
+    pub(crate) recent_drain_bytes: u64,
+    pub(crate) consecutive_stalls: u8,
+    pub(crate) consecutive_skips: u8,
+    pub(crate) penalty_score: u16,
+    pub(crate) pressure_class: FlowPressureClass,
+    pub(crate) standing_state: StandingQueueState,
+    pub(crate) scheduler_state: FlowSchedulerState,
+    pub(crate) bucket_id: usize,
+    pub(crate) in_active_ring: bool,
+}
+
+impl FlowFairnessState {
+    pub(crate) fn new(flow_id: u64, worker_id: u16, bucket_id: usize) -> Self {
+        Self {
+            _flow_id: flow_id,
+            _worker_id: worker_id,
+            pending_bytes: 0,
+            deficit_bytes: 0,
+            queue_started_at: None,
+            last_drain_at: None,
+            recent_drain_bytes: 0,
+            consecutive_stalls: 0,
+            consecutive_skips: 0,
+            penalty_score: 0,
+            pressure_class: FlowPressureClass::Healthy,
+            standing_state: StandingQueueState::Transient,
+            scheduler_state: FlowSchedulerState::Idle,
+            bucket_id,
+            in_active_ring: false,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum AdmissionDecision {
+    Admit,
+    RejectWorkerCap,
+    RejectFlowCap,
+    RejectBucketCap,
+    RejectSaturated,
+    RejectStandingFlow,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) enum SchedulerDecision {
+    Idle,
+    Dispatch(DispatchCandidate),
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct DispatchCandidate {
+    pub(crate) frame: QueuedFrame,
+    pub(crate) pressure_state: PressureState,
+    pub(crate) flow_class: FlowPressureClass,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum DispatchFeedback {
+    Routed,
+    QueueFull,
+    ChannelClosed,
+    NoConn,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum DispatchAction {
+    Continue,
+    CloseFlow,
+}

src/transport/middle_proxy/fairness/pressure.rs

@@ -0,0 +1,214 @@
+use std::time::{Duration, Instant};
+
+use super::model::PressureState;
+
+#[derive(Debug, Clone, Copy)]
+pub(crate) struct PressureSignals {
+    pub(crate) active_flows: usize,
+    pub(crate) total_queued_bytes: u64,
+    pub(crate) standing_flows: usize,
+    pub(crate) backpressured_flows: usize,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct PressureConfig {
+    pub(crate) evaluate_every_rounds: u32,
+    pub(crate) transition_hysteresis_rounds: u8,
+    pub(crate) standing_ratio_pressured_pct: u8,
+    pub(crate) standing_ratio_shedding_pct: u8,
+    pub(crate) standing_ratio_saturated_pct: u8,
+    pub(crate) queue_ratio_pressured_pct: u8,
+    pub(crate) queue_ratio_shedding_pct: u8,
+    pub(crate) queue_ratio_saturated_pct: u8,
+    pub(crate) reject_window: Duration,
+    pub(crate) rejects_pressured: u32,
+    pub(crate) rejects_shedding: u32,
+    pub(crate) rejects_saturated: u32,
+    pub(crate) stalls_pressured: u32,
+    pub(crate) stalls_shedding: u32,
+    pub(crate) stalls_saturated: u32,
+}
+
+impl Default for PressureConfig {
+    fn default() -> Self {
+        Self {
+            evaluate_every_rounds: 8,
+            transition_hysteresis_rounds: 3,
+            standing_ratio_pressured_pct: 20,
+            standing_ratio_shedding_pct: 35,
+            standing_ratio_saturated_pct: 50,
+            queue_ratio_pressured_pct: 65,
+            queue_ratio_shedding_pct: 82,
+            queue_ratio_saturated_pct: 94,
+            reject_window: Duration::from_secs(2),
+            rejects_pressured: 32,
+            rejects_shedding: 96,
+            rejects_saturated: 256,
+            stalls_pressured: 32,
+            stalls_shedding: 96,
+            stalls_saturated: 256,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct PressureEvaluator {
+    state: PressureState,
+    candidate_state: PressureState,
+    candidate_hits: u8,
+    rounds_since_eval: u32,
+    window_started_at: Instant,
+    admission_rejects_window: u32,
+    route_stalls_window: u32,
+}
+
+impl PressureEvaluator {
+    pub(crate) fn new(now: Instant) -> Self {
+        Self {
+            state: PressureState::Normal,
+            candidate_state: PressureState::Normal,
+            candidate_hits: 0,
+            rounds_since_eval: 0,
+            window_started_at: now,
+            admission_rejects_window: 0,
+            route_stalls_window: 0,
+        }
+    }
+
+    #[inline]
+    pub(crate) fn state(&self) -> PressureState {
+        self.state
+    }
+
+    pub(crate) fn note_admission_reject(&mut self, now: Instant, cfg: &PressureConfig) {
+        self.rotate_window_if_needed(now, cfg);
+        self.admission_rejects_window = self.admission_rejects_window.saturating_add(1);
+    }
+
+    pub(crate) fn note_route_stall(&mut self, now: Instant, cfg: &PressureConfig) {
+        self.rotate_window_if_needed(now, cfg);
+        self.route_stalls_window = self.route_stalls_window.saturating_add(1);
+    }
+
+    pub(crate) fn maybe_evaluate(
+        &mut self,
+        now: Instant,
+        cfg: &PressureConfig,
+        max_total_queued_bytes: u64,
+        signals: PressureSignals,
+        force: bool,
+    ) -> PressureState {
+        self.rotate_window_if_needed(now, cfg);
+        self.rounds_since_eval = self.rounds_since_eval.saturating_add(1);
+        if !force && self.rounds_since_eval < cfg.evaluate_every_rounds.max(1) {
+            return self.state;
+        }
+        self.rounds_since_eval = 0;
+
+        let target = self.derive_target_state(cfg, max_total_queued_bytes, signals);
+        if target == self.state {
+            self.candidate_state = target;
+            self.candidate_hits = 0;
+            return self.state;
+        }
+
+        if self.candidate_state == target {
+            self.candidate_hits = self.candidate_hits.saturating_add(1);
+        } else {
+            self.candidate_state = target;
+            self.candidate_hits = 1;
+        }
+
+        if self.candidate_hits >= cfg.transition_hysteresis_rounds.max(1) {
+            self.state = target;
+            self.candidate_hits = 0;
+        }
+
+        self.state
+    }
+
+    fn derive_target_state(
+        &self,
+        cfg: &PressureConfig,
+        max_total_queued_bytes: u64,
+        signals: PressureSignals,
+    ) -> PressureState {
+        let queue_ratio_pct = if max_total_queued_bytes == 0 {
+            100
+        } else {
+            ((signals.total_queued_bytes.saturating_mul(100)) / max_total_queued_bytes).min(100)
+                as u8
+        };
+
+        let standing_ratio_pct = if signals.active_flows == 0 {
+            0
+        } else {
+            ((signals.standing_flows.saturating_mul(100)) / signals.active_flows).min(100) as u8
+        };
+
+        let mut pressure_score = 0u8;
+
+        if queue_ratio_pct >= cfg.queue_ratio_pressured_pct {
+            pressure_score = pressure_score.max(1);
+        }
+        if queue_ratio_pct >= cfg.queue_ratio_shedding_pct {
+            pressure_score = pressure_score.max(2);
+        }
+        if queue_ratio_pct >= cfg.queue_ratio_saturated_pct {
+            pressure_score = pressure_score.max(3);
+        }
+
+        if standing_ratio_pct >= cfg.standing_ratio_pressured_pct {
+            pressure_score = pressure_score.max(1);
+        }
+        if standing_ratio_pct >= cfg.standing_ratio_shedding_pct {
+            pressure_score = pressure_score.max(2);
+        }
+        if standing_ratio_pct >= cfg.standing_ratio_saturated_pct {
+            pressure_score = pressure_score.max(3);
+        }
+
+        if self.admission_rejects_window >= cfg.rejects_pressured {
+            pressure_score = pressure_score.max(1);
+        }
+        if self.admission_rejects_window >= cfg.rejects_shedding {
+            pressure_score = pressure_score.max(2);
+        }
+        if self.admission_rejects_window >= cfg.rejects_saturated {
+            pressure_score = pressure_score.max(3);
+        }
+
+        if self.route_stalls_window >= cfg.stalls_pressured {
+            pressure_score = pressure_score.max(1);
+        }
+        if self.route_stalls_window >= cfg.stalls_shedding {
+            pressure_score = pressure_score.max(2);
+        }
+        if self.route_stalls_window >= cfg.stalls_saturated {
+            pressure_score = pressure_score.max(3);
+        }
+
+        if signals.backpressured_flows > signals.active_flows.saturating_div(2)
+            && signals.active_flows > 0
+        {
+            pressure_score = pressure_score.max(2);
+        }
+
+        match pressure_score {
+            0 => PressureState::Normal,
+            1 => PressureState::Pressured,
+            2 => PressureState::Shedding,
+            _ => PressureState::Saturated,
+        }
+    }
+
+    fn rotate_window_if_needed(&mut self, now: Instant, cfg: &PressureConfig) {
+        if now.saturating_duration_since(self.window_started_at) < cfg.reject_window {
+            return;
+        }
+
+        self.window_started_at = now;
+        self.admission_rejects_window = 0;
+        self.route_stalls_window = 0;
+    }
+}

src/transport/middle_proxy/fairness/scheduler.rs

@@ -0,0 +1,556 @@
+use std::collections::{HashMap, VecDeque};
+use std::time::{Duration, Instant};
+
+use bytes::Bytes;
+
+use super::model::{
+    AdmissionDecision, DispatchAction, DispatchCandidate, DispatchFeedback, FlowFairnessState,
+    FlowPressureClass, FlowSchedulerState, PressureState, QueuedFrame, SchedulerDecision,
+    StandingQueueState,
+};
+use super::pressure::{PressureConfig, PressureEvaluator, PressureSignals};
+
+#[derive(Debug, Clone)]
+pub(crate) struct WorkerFairnessConfig {
+    pub(crate) worker_id: u16,
+    pub(crate) max_active_flows: usize,
+    pub(crate) max_total_queued_bytes: u64,
+    pub(crate) max_flow_queued_bytes: u64,
+    pub(crate) base_quantum_bytes: u32,
+    pub(crate) pressured_quantum_bytes: u32,
+    pub(crate) penalized_quantum_bytes: u32,
+    pub(crate) standing_queue_min_age: Duration,
+    pub(crate) standing_queue_min_backlog_bytes: u64,
+    pub(crate) standing_stall_threshold: u8,
+    pub(crate) max_consecutive_stalls_before_shed: u8,
+    pub(crate) max_consecutive_stalls_before_close: u8,
+    pub(crate) soft_bucket_count: usize,
+    pub(crate) soft_bucket_share_pct: u8,
+    pub(crate) pressure: PressureConfig,
+}
+
+impl Default for WorkerFairnessConfig {
+    fn default() -> Self {
+        Self {
+            worker_id: 0,
+            max_active_flows: 4096,
+            max_total_queued_bytes: 16 * 1024 * 1024,
+            max_flow_queued_bytes: 512 * 1024,
+            base_quantum_bytes: 32 * 1024,
+            pressured_quantum_bytes: 16 * 1024,
+            penalized_quantum_bytes: 8 * 1024,
+            standing_queue_min_age: Duration::from_millis(250),
+            standing_queue_min_backlog_bytes: 64 * 1024,
+            standing_stall_threshold: 3,
+            max_consecutive_stalls_before_shed: 4,
+            max_consecutive_stalls_before_close: 16,
+            soft_bucket_count: 64,
+            soft_bucket_share_pct: 25,
+            pressure: PressureConfig::default(),
+        }
+    }
+}
+
+struct FlowEntry {
+    fairness: FlowFairnessState,
+    queue: VecDeque<QueuedFrame>,
+}
+
+impl FlowEntry {
+    fn new(flow_id: u64, worker_id: u16, bucket_id: usize) -> Self {
+        Self {
+            fairness: FlowFairnessState::new(flow_id, worker_id, bucket_id),
+            queue: VecDeque::new(),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, Default)]
+pub(crate) struct WorkerFairnessSnapshot {
+    pub(crate) pressure_state: PressureState,
+    pub(crate) active_flows: usize,
+    pub(crate) total_queued_bytes: u64,
+    pub(crate) standing_flows: usize,
+    pub(crate) backpressured_flows: usize,
+    pub(crate) scheduler_rounds: u64,
+    pub(crate) deficit_grants: u64,
+    pub(crate) deficit_skips: u64,
+    pub(crate) enqueue_rejects: u64,
+    pub(crate) shed_drops: u64,
+    pub(crate) fairness_penalties: u64,
+    pub(crate) downstream_stalls: u64,
+}
+
+pub(crate) struct WorkerFairnessState {
+    config: WorkerFairnessConfig,
+    pressure: PressureEvaluator,
+    flows: HashMap<u64, FlowEntry>,
+    active_ring: VecDeque<u64>,
+    total_queued_bytes: u64,
+    bucket_queued_bytes: Vec<u64>,
+    bucket_active_flows: Vec<usize>,
+    standing_flow_count: usize,
+    backpressured_flow_count: usize,
+    scheduler_rounds: u64,
+    deficit_grants: u64,
+    deficit_skips: u64,
+    enqueue_rejects: u64,
+    shed_drops: u64,
+    fairness_penalties: u64,
+    downstream_stalls: u64,
+}
+
+impl WorkerFairnessState {
+    pub(crate) fn new(config: WorkerFairnessConfig, now: Instant) -> Self {
+        let bucket_count = config.soft_bucket_count.max(1);
+        Self {
+            config,
+            pressure: PressureEvaluator::new(now),
+            flows: HashMap::new(),
+            active_ring: VecDeque::new(),
+            total_queued_bytes: 0,
+            bucket_queued_bytes: vec![0; bucket_count],
+            bucket_active_flows: vec![0; bucket_count],
+            standing_flow_count: 0,
+            backpressured_flow_count: 0,
+            scheduler_rounds: 0,
+            deficit_grants: 0,
+            deficit_skips: 0,
+            enqueue_rejects: 0,
+            shed_drops: 0,
+            fairness_penalties: 0,
+            downstream_stalls: 0,
+        }
+    }
+
+    pub(crate) fn pressure_state(&self) -> PressureState {
+        self.pressure.state()
+    }
+
+    pub(crate) fn snapshot(&self) -> WorkerFairnessSnapshot {
+        WorkerFairnessSnapshot {
+            pressure_state: self.pressure.state(),
+            active_flows: self.flows.len(),
+            total_queued_bytes: self.total_queued_bytes,
+            standing_flows: self.standing_flow_count,
+            backpressured_flows: self.backpressured_flow_count,
+            scheduler_rounds: self.scheduler_rounds,
+            deficit_grants: self.deficit_grants,
+            deficit_skips: self.deficit_skips,
+            enqueue_rejects: self.enqueue_rejects,
+            shed_drops: self.shed_drops,
+            fairness_penalties: self.fairness_penalties,
+            downstream_stalls: self.downstream_stalls,
+        }
+    }
+
+    pub(crate) fn enqueue_data(
+        &mut self,
+        conn_id: u64,
+        flags: u32,
+        data: Bytes,
+        now: Instant,
+    ) -> AdmissionDecision {
+        let frame = QueuedFrame {
+            conn_id,
+            flags,
+            data,
+            enqueued_at: now,
+        };
+        let frame_bytes = frame.queued_bytes();
+
+        if self.pressure.state() == PressureState::Saturated {
+            self.pressure
+                .note_admission_reject(now, &self.config.pressure);
+            self.enqueue_rejects = self.enqueue_rejects.saturating_add(1);
+            return AdmissionDecision::RejectSaturated;
+        }
+
+        if self.total_queued_bytes.saturating_add(frame_bytes) > self.config.max_total_queued_bytes
+        {
+            self.pressure
+                .note_admission_reject(now, &self.config.pressure);
+            self.enqueue_rejects = self.enqueue_rejects.saturating_add(1);
+            self.evaluate_pressure(now, true);
+            return AdmissionDecision::RejectWorkerCap;
+        }
+
+        if !self.flows.contains_key(&conn_id) && self.flows.len() >= self.config.max_active_flows {
+            self.pressure
+                .note_admission_reject(now, &self.config.pressure);
+            self.enqueue_rejects = self.enqueue_rejects.saturating_add(1);
+            self.evaluate_pressure(now, true);
+            return AdmissionDecision::RejectWorkerCap;
+        }
+
+        let bucket_id = self.bucket_for(conn_id);
+        let bucket_cap = self
+            .config
+            .max_total_queued_bytes
+            .saturating_mul(self.config.soft_bucket_share_pct.max(1) as u64)
+            .saturating_div(100)
+            .max(self.config.max_flow_queued_bytes);
+        if self.bucket_queued_bytes[bucket_id].saturating_add(frame_bytes) > bucket_cap {
+            self.pressure
+                .note_admission_reject(now, &self.config.pressure);
+            self.enqueue_rejects = self.enqueue_rejects.saturating_add(1);
+            self.evaluate_pressure(now, true);
+            return AdmissionDecision::RejectBucketCap;
+        }
+
+        let entry = if let Some(flow) = self.flows.get_mut(&conn_id) {
+            flow
+        } else {
+            self.bucket_active_flows[bucket_id] =
+                self.bucket_active_flows[bucket_id].saturating_add(1);
+            self.flows.insert(
+                conn_id,
+                FlowEntry::new(conn_id, self.config.worker_id, bucket_id),
+            );
+            self.flows
+                .get_mut(&conn_id)
+                .expect("flow inserted must be retrievable")
+        };
+
+        if entry.fairness.pending_bytes.saturating_add(frame_bytes)
+            > self.config.max_flow_queued_bytes
+        {
+            self.pressure
+                .note_admission_reject(now, &self.config.pressure);
+            self.enqueue_rejects = self.enqueue_rejects.saturating_add(1);
+            self.evaluate_pressure(now, true);
+            return AdmissionDecision::RejectFlowCap;
+        }
+
+        if self.pressure.state() >= PressureState::Shedding
+            && entry.fairness.standing_state == StandingQueueState::Standing
+        {
+            self.pressure
+                .note_admission_reject(now, &self.config.pressure);
+            self.enqueue_rejects = self.enqueue_rejects.saturating_add(1);
+            self.evaluate_pressure(now, true);
+            return AdmissionDecision::RejectStandingFlow;
+        }
+
+        entry.fairness.pending_bytes = entry.fairness.pending_bytes.saturating_add(frame_bytes);
+        if entry.fairness.queue_started_at.is_none() {
+            entry.fairness.queue_started_at = Some(now);
+        }
+        entry.queue.push_back(frame);
+
+        self.total_queued_bytes = self.total_queued_bytes.saturating_add(frame_bytes);
+        self.bucket_queued_bytes[bucket_id] =
+            self.bucket_queued_bytes[bucket_id].saturating_add(frame_bytes);
+
+        if !entry.fairness.in_active_ring {
+            entry.fairness.in_active_ring = true;
+            self.active_ring.push_back(conn_id);
+        }
+
+        self.evaluate_pressure(now, true);
+        AdmissionDecision::Admit
+    }
+
+    pub(crate) fn next_decision(&mut self, now: Instant) -> SchedulerDecision {
+        self.scheduler_rounds = self.scheduler_rounds.saturating_add(1);
+        self.evaluate_pressure(now, false);
+
+        let active_len = self.active_ring.len();
+        for _ in 0..active_len {
+            let Some(conn_id) = self.active_ring.pop_front() else {
+                break;
+            };
+
+            let mut candidate = None;
+            let mut requeue_active = false;
+            let mut drained_bytes = 0u64;
+            let mut bucket_id = 0usize;
+            let pressure_state = self.pressure.state();
+
+            if let Some(flow) = self.flows.get_mut(&conn_id) {
+                bucket_id = flow.fairness.bucket_id;
+
+                if flow.queue.is_empty() {
+                    flow.fairness.in_active_ring = false;
+                    flow.fairness.scheduler_state = FlowSchedulerState::Idle;
+                    flow.fairness.pending_bytes = 0;
+                    flow.fairness.queue_started_at = None;
+                    continue;
+                }
+
+                Self::classify_flow(&self.config, pressure_state, now, &mut flow.fairness);
+
+                let quantum =
+                    Self::effective_quantum_bytes(&self.config, pressure_state, &flow.fairness);
+                flow.fairness.deficit_bytes = flow
+                    .fairness
+                    .deficit_bytes
+                    .saturating_add(i64::from(quantum));
+                self.deficit_grants = self.deficit_grants.saturating_add(1);
+
+                let front_len = flow.queue.front().map_or(0, |front| front.queued_bytes());
+                if flow.fairness.deficit_bytes < front_len as i64 {
+                    flow.fairness.consecutive_skips =
+                        flow.fairness.consecutive_skips.saturating_add(1);
+                    self.deficit_skips = self.deficit_skips.saturating_add(1);
+                    requeue_active = true;
+                } else if let Some(frame) = flow.queue.pop_front() {
+                    drained_bytes = frame.queued_bytes();
+                    flow.fairness.pending_bytes =
+                        flow.fairness.pending_bytes.saturating_sub(drained_bytes);
+                    flow.fairness.deficit_bytes = flow
+                        .fairness
+                        .deficit_bytes
+                        .saturating_sub(drained_bytes as i64);
+                    flow.fairness.consecutive_skips = 0;
+                    flow.fairness.queue_started_at =
+                        flow.queue.front().map(|front| front.enqueued_at);
+                    requeue_active = !flow.queue.is_empty();
+                    if !requeue_active {
+                        flow.fairness.scheduler_state = FlowSchedulerState::Idle;
+                        flow.fairness.in_active_ring = false;
+                    }
+                    candidate = Some(DispatchCandidate {
+                        pressure_state,
+                        flow_class: flow.fairness.pressure_class,
+                        frame,
+                    });
+                }
+            }
+
+            if drained_bytes > 0 {
+                self.total_queued_bytes = self.total_queued_bytes.saturating_sub(drained_bytes);
+                self.bucket_queued_bytes[bucket_id] =
+                    self.bucket_queued_bytes[bucket_id].saturating_sub(drained_bytes);
+            }
+
+            if requeue_active {
+                if let Some(flow) = self.flows.get_mut(&conn_id) {
+                    flow.fairness.in_active_ring = true;
+                }
+                self.active_ring.push_back(conn_id);
+            }
+
+            if let Some(candidate) = candidate {
+                return SchedulerDecision::Dispatch(candidate);
+            }
+        }
+
+        SchedulerDecision::Idle
+    }
+
+    pub(crate) fn apply_dispatch_feedback(
+        &mut self,
+        conn_id: u64,
+        candidate: DispatchCandidate,
+        feedback: DispatchFeedback,
+        now: Instant,
+    ) -> DispatchAction {
+        match feedback {
+            DispatchFeedback::Routed => {
+                if let Some(flow) = self.flows.get_mut(&conn_id) {
+                    flow.fairness.last_drain_at = Some(now);
+                    flow.fairness.recent_drain_bytes = flow
+                        .fairness
+                        .recent_drain_bytes
+                        .saturating_add(candidate.frame.queued_bytes());
+                    flow.fairness.consecutive_stalls = 0;
+                    if flow.fairness.scheduler_state != FlowSchedulerState::Idle {
+                        flow.fairness.scheduler_state = FlowSchedulerState::Active;
+                    }
+                }
+                self.evaluate_pressure(now, false);
+                DispatchAction::Continue
+            }
+            DispatchFeedback::QueueFull => {
+                self.pressure.note_route_stall(now, &self.config.pressure);
+                self.downstream_stalls = self.downstream_stalls.saturating_add(1);
+                let Some(flow) = self.flows.get_mut(&conn_id) else {
+                    self.evaluate_pressure(now, true);
+                    return DispatchAction::Continue;
+                };
+
+                flow.fairness.consecutive_stalls =
+                    flow.fairness.consecutive_stalls.saturating_add(1);
+                flow.fairness.scheduler_state = FlowSchedulerState::Backpressured;
+                flow.fairness.pressure_class = FlowPressureClass::Backpressured;
+
+                let state = self.pressure.state();
+                let should_shed_frame = matches!(state, PressureState::Saturated)
+                    || (matches!(state, PressureState::Shedding)
+                        && flow.fairness.standing_state == StandingQueueState::Standing
+                        && flow.fairness.consecutive_stalls
+                            >= self.config.max_consecutive_stalls_before_shed);
+
+                if should_shed_frame {
+                    self.shed_drops = self.shed_drops.saturating_add(1);
+                    self.fairness_penalties = self.fairness_penalties.saturating_add(1);
+                } else {
+                    let frame_bytes = candidate.frame.queued_bytes();
+                    flow.queue.push_front(candidate.frame);
+                    flow.fairness.pending_bytes =
+                        flow.fairness.pending_bytes.saturating_add(frame_bytes);
+                    flow.fairness.queue_started_at =
+                        flow.queue.front().map(|front| front.enqueued_at);
+                    self.total_queued_bytes = self.total_queued_bytes.saturating_add(frame_bytes);
+                    self.bucket_queued_bytes[flow.fairness.bucket_id] = self.bucket_queued_bytes
+                        [flow.fairness.bucket_id]
+                        .saturating_add(frame_bytes);
+                    if !flow.fairness.in_active_ring {
+                        flow.fairness.in_active_ring = true;
+                        self.active_ring.push_back(conn_id);
+                    }
+                }
+
+                if flow.fairness.consecutive_stalls
+                    >= self.config.max_consecutive_stalls_before_close
+                    && self.pressure.state() == PressureState::Saturated
+                {
+                    self.remove_flow(conn_id);
+                    self.evaluate_pressure(now, true);
+                    return DispatchAction::CloseFlow;
+                }
+
+                self.evaluate_pressure(now, true);
+                DispatchAction::Continue
+            }
+            DispatchFeedback::ChannelClosed | DispatchFeedback::NoConn => {
+                self.remove_flow(conn_id);
+                self.evaluate_pressure(now, true);
+                DispatchAction::CloseFlow
+            }
+        }
+    }
+
+    pub(crate) fn remove_flow(&mut self, conn_id: u64) {
+        let Some(entry) = self.flows.remove(&conn_id) else {
+            return;
+        };
+
+        self.bucket_active_flows[entry.fairness.bucket_id] =
+            self.bucket_active_flows[entry.fairness.bucket_id].saturating_sub(1);
+
+        let mut reclaimed = 0u64;
+        for frame in entry.queue {
+            reclaimed = reclaimed.saturating_add(frame.queued_bytes());
+        }
+        self.total_queued_bytes = self.total_queued_bytes.saturating_sub(reclaimed);
+        self.bucket_queued_bytes[entry.fairness.bucket_id] =
+            self.bucket_queued_bytes[entry.fairness.bucket_id].saturating_sub(reclaimed);
+    }
+
+    fn evaluate_pressure(&mut self, now: Instant, force: bool) {
+        let mut standing = 0usize;
+        let mut backpressured = 0usize;
+
+        for flow in self.flows.values_mut() {
+            Self::classify_flow(&self.config, self.pressure.state(), now, &mut flow.fairness);
+            if flow.fairness.standing_state == StandingQueueState::Standing {
+                standing = standing.saturating_add(1);
+            }
+            if matches!(
+                flow.fairness.scheduler_state,
+                FlowSchedulerState::Backpressured
+                    | FlowSchedulerState::Penalized
+                    | FlowSchedulerState::SheddingCandidate
+            ) {
+                backpressured = backpressured.saturating_add(1);
+            }
+        }
+
+        self.standing_flow_count = standing;
+        self.backpressured_flow_count = backpressured;
+
+        let _ = self.pressure.maybe_evaluate(
+            now,
+            &self.config.pressure,
+            self.config.max_total_queued_bytes,
+            PressureSignals {
+                active_flows: self.flows.len(),
+                total_queued_bytes: self.total_queued_bytes,
+                standing_flows: standing,
+                backpressured_flows: backpressured,
+            },
+            force,
+        );
+    }
+
+    fn classify_flow(
+        config: &WorkerFairnessConfig,
+        pressure_state: PressureState,
+        now: Instant,
+        fairness: &mut FlowFairnessState,
+    ) {
+        if fairness.pending_bytes == 0 {
+            fairness.pressure_class = FlowPressureClass::Healthy;
+            fairness.standing_state = StandingQueueState::Transient;
+            fairness.scheduler_state = FlowSchedulerState::Idle;
+            fairness.penalty_score = fairness.penalty_score.saturating_sub(1);
+            return;
+        }
+
+        let queue_age = fairness
+            .queue_started_at
+            .map(|ts| now.saturating_duration_since(ts))
+            .unwrap_or_default();
+        let drain_stalled = fairness
+            .last_drain_at
+            .map(|ts| now.saturating_duration_since(ts) >= config.standing_queue_min_age)
+            .unwrap_or(true);
+
+        let standing = fairness.pending_bytes >= config.standing_queue_min_backlog_bytes
+            && queue_age >= config.standing_queue_min_age
+            && (fairness.consecutive_stalls >= config.standing_stall_threshold || drain_stalled);
+
+        if standing {
+            fairness.standing_state = StandingQueueState::Standing;
+            fairness.pressure_class = FlowPressureClass::Standing;
+            fairness.penalty_score = fairness.penalty_score.saturating_add(1);
+            fairness.scheduler_state = if pressure_state >= PressureState::Shedding {
+                FlowSchedulerState::SheddingCandidate
+            } else {
+                FlowSchedulerState::Penalized
+            };
+            return;
+        }
+
+        fairness.standing_state = StandingQueueState::Transient;
+        if fairness.consecutive_stalls > 0 {
+            fairness.pressure_class = FlowPressureClass::Backpressured;
+            fairness.scheduler_state = FlowSchedulerState::Backpressured;
+        } else if fairness.pending_bytes >= config.standing_queue_min_backlog_bytes {
+            fairness.pressure_class = FlowPressureClass::Bursty;
+            fairness.scheduler_state = FlowSchedulerState::Active;
+        } else {
+            fairness.pressure_class = FlowPressureClass::Healthy;
+            fairness.scheduler_state = FlowSchedulerState::Active;
+        }
+        fairness.penalty_score = fairness.penalty_score.saturating_sub(1);
+    }
+
+    fn effective_quantum_bytes(
+        config: &WorkerFairnessConfig,
+        pressure_state: PressureState,
+        fairness: &FlowFairnessState,
+    ) -> u32 {
+        let penalized = matches!(
+            fairness.scheduler_state,
+            FlowSchedulerState::Penalized | FlowSchedulerState::SheddingCandidate
+        );
+
+        if penalized {
+            return config.penalized_quantum_bytes.max(1);
+        }
+
+        match pressure_state {
+            PressureState::Normal => config.base_quantum_bytes.max(1),
+            PressureState::Pressured => config.pressured_quantum_bytes.max(1),
+            PressureState::Shedding => config.pressured_quantum_bytes.max(1),
+            PressureState::Saturated => config.penalized_quantum_bytes.max(1),
+        }
+    }
+
+    fn bucket_for(&self, conn_id: u64) -> usize {
+        (conn_id as usize) % self.bucket_queued_bytes.len().max(1)
+    }
+}

src/transport/middle_proxy/mod.rs

@@ -2,6 +2,10 @@
 
 mod codec;
 mod config_updater;
+mod fairness;
+#[cfg(test)]
+#[path = "tests/fairness_security_tests.rs"]
+mod fairness_security_tests;
 mod handshake;
 mod health;
 #[cfg(test)]

src/transport/middle_proxy/reader.rs

@@ -20,11 +20,15 @@ use crate::protocol::constants::*;
 use crate::stats::Stats;
 
 use super::codec::{RpcChecksumMode, WriterCommand, rpc_crc};
+use super::fairness::{
+    AdmissionDecision, DispatchAction, DispatchFeedback, SchedulerDecision, WorkerFairnessConfig,
+    WorkerFairnessSnapshot, WorkerFairnessState,
+};
 use super::registry::RouteResult;
 use super::{ConnRegistry, MeResponse};
-
 const DATA_ROUTE_MAX_ATTEMPTS: usize = 3;
 const DATA_ROUTE_QUEUE_FULL_STARVATION_THRESHOLD: u8 = 3;
+const FAIRNESS_DRAIN_BUDGET_PER_LOOP: usize = 128;
 
 fn should_close_on_route_result_for_data(result: RouteResult) -> bool {
     matches!(result, RouteResult::NoConn | RouteResult::ChannelClosed)
@@ -77,6 +81,118 @@ async fn route_data_with_retry(
     }
 }
 
+#[inline]
+fn route_feedback(result: RouteResult) -> DispatchFeedback {
+    match result {
+        RouteResult::Routed => DispatchFeedback::Routed,
+        RouteResult::NoConn => DispatchFeedback::NoConn,
+        RouteResult::ChannelClosed => DispatchFeedback::ChannelClosed,
+        RouteResult::QueueFullBase | RouteResult::QueueFullHigh => DispatchFeedback::QueueFull,
+    }
+}
+
+fn report_route_drop(result: RouteResult, stats: &Stats) {
+    match result {
+        RouteResult::NoConn => stats.increment_me_route_drop_no_conn(),
+        RouteResult::ChannelClosed => stats.increment_me_route_drop_channel_closed(),
+        RouteResult::QueueFullBase => {
+            stats.increment_me_route_drop_queue_full();
+            stats.increment_me_route_drop_queue_full_base();
+        }
+        RouteResult::QueueFullHigh => {
+            stats.increment_me_route_drop_queue_full();
+            stats.increment_me_route_drop_queue_full_high();
+        }
+        RouteResult::Routed => {}
+    }
+}
+
+fn apply_fairness_metrics_delta(
+    stats: &Stats,
+    prev: &mut WorkerFairnessSnapshot,
+    current: WorkerFairnessSnapshot,
+) {
+    stats.set_me_fair_active_flows_gauge(current.active_flows as u64);
+    stats.set_me_fair_queued_bytes_gauge(current.total_queued_bytes);
+    stats.set_me_fair_standing_flows_gauge(current.standing_flows as u64);
+    stats.set_me_fair_backpressured_flows_gauge(current.backpressured_flows as u64);
+    stats.set_me_fair_pressure_state_gauge(current.pressure_state.as_u8() as u64);
+    stats.add_me_fair_scheduler_rounds_total(
+        current
+            .scheduler_rounds
+            .saturating_sub(prev.scheduler_rounds),
+    );
+    stats.add_me_fair_deficit_grants_total(
+        current.deficit_grants.saturating_sub(prev.deficit_grants),
+    );
+    stats.add_me_fair_deficit_skips_total(current.deficit_skips.saturating_sub(prev.deficit_skips));
+    stats.add_me_fair_enqueue_rejects_total(
+        current.enqueue_rejects.saturating_sub(prev.enqueue_rejects),
+    );
+    stats.add_me_fair_shed_drops_total(current.shed_drops.saturating_sub(prev.shed_drops));
+    stats.add_me_fair_penalties_total(
+        current
+            .fairness_penalties
+            .saturating_sub(prev.fairness_penalties),
+    );
+    stats.add_me_fair_downstream_stalls_total(
+        current
+            .downstream_stalls
+            .saturating_sub(prev.downstream_stalls),
+    );
+    *prev = current;
+}
+
+async fn drain_fairness_scheduler(
+    fairness: &mut WorkerFairnessState,
+    reg: &ConnRegistry,
+    tx: &mpsc::Sender<WriterCommand>,
+    data_route_queue_full_streak: &mut HashMap<u64, u8>,
+    route_wait_ms: u64,
+    stats: &Stats,
+) {
+    for _ in 0..FAIRNESS_DRAIN_BUDGET_PER_LOOP {
+        let now = Instant::now();
+        let SchedulerDecision::Dispatch(candidate) = fairness.next_decision(now) else {
+            break;
+        };
+        let cid = candidate.frame.conn_id;
+        let _pressure_state = candidate.pressure_state;
+        let _flow_class = candidate.flow_class;
+        let routed = route_data_with_retry(
+            reg,
+            cid,
+            candidate.frame.flags,
+            candidate.frame.data.clone(),
+            route_wait_ms,
+        )
+        .await;
+        if matches!(routed, RouteResult::Routed) {
+            data_route_queue_full_streak.remove(&cid);
+        } else {
+            report_route_drop(routed, stats);
+        }
+        let action = fairness.apply_dispatch_feedback(cid, candidate, route_feedback(routed), now);
+        if is_data_route_queue_full(routed) {
+            let streak = data_route_queue_full_streak.entry(cid).or_insert(0);
+            *streak = streak.saturating_add(1);
+            if should_close_on_queue_full_streak(*streak) {
+                fairness.remove_flow(cid);
+                data_route_queue_full_streak.remove(&cid);
+                reg.unregister(cid).await;
+                send_close_conn(tx, cid).await;
+                continue;
+            }
+        }
+        if action == DispatchAction::CloseFlow || should_close_on_route_result_for_data(routed) {
+            fairness.remove_flow(cid);
+            data_route_queue_full_streak.remove(&cid);
+            reg.unregister(cid).await;
+            send_close_conn(tx, cid).await;
+        }
+    }
+}
+
 pub(crate) async fn reader_loop(
     mut rd: tokio::io::ReadHalf<TcpStream>,
     dk: [u8; 32],
@@ -98,7 +214,21 @@ pub(crate) async fn reader_loop(
     let mut raw = enc_leftover;
     let mut expected_seq: i32 = 0;
     let mut data_route_queue_full_streak = HashMap::<u64, u8>::new();
-
+    let mut fairness = WorkerFairnessState::new(
+        WorkerFairnessConfig {
+            worker_id: (writer_id as u16).saturating_add(1),
+            max_active_flows: reg.route_channel_capacity().saturating_mul(4).max(256),
+            max_total_queued_bytes: (reg.route_channel_capacity() as u64)
+                .saturating_mul(16 * 1024)
+                .max(4 * 1024 * 1024),
+            max_flow_queued_bytes: (reg.route_channel_capacity() as u64)
+                .saturating_mul(2 * 1024)
+                .clamp(64 * 1024, 2 * 1024 * 1024),
+            ..WorkerFairnessConfig::default()
+        },
+        Instant::now(),
+    );
+    let mut fairness_snapshot = fairness.snapshot();
     loop {
         let mut tmp = [0u8; 65_536];
         let n = tokio::select! {
@@ -181,36 +311,20 @@ pub(crate) async fn reader_loop(
                 let data = body.slice(12..);
                 trace!(cid, flags, len = data.len(), "RPC_PROXY_ANS");
 
-                let route_wait_ms = reader_route_data_wait_ms.load(Ordering::Relaxed);
-                let routed =
-                    route_data_with_retry(reg.as_ref(), cid, flags, data, route_wait_ms).await;
-                if matches!(routed, RouteResult::Routed) {
-                    data_route_queue_full_streak.remove(&cid);
-                    continue;
-                }
-                match routed {
-                    RouteResult::NoConn => stats.increment_me_route_drop_no_conn(),
-                    RouteResult::ChannelClosed => stats.increment_me_route_drop_channel_closed(),
-                    RouteResult::QueueFullBase => {
-                        stats.increment_me_route_drop_queue_full();
-                        stats.increment_me_route_drop_queue_full_base();
-                    }
-                    RouteResult::QueueFullHigh => {
-                        stats.increment_me_route_drop_queue_full();
-                        stats.increment_me_route_drop_queue_full_high();
-                    }
-                    RouteResult::Routed => {}
-                }
-                if should_close_on_route_result_for_data(routed) {
-                    data_route_queue_full_streak.remove(&cid);
-                    reg.unregister(cid).await;
-                    send_close_conn(&tx, cid).await;
-                    continue;
-                }
-                if is_data_route_queue_full(routed) {
+                let admission = fairness.enqueue_data(cid, flags, data, Instant::now());
+                if !matches!(admission, AdmissionDecision::Admit) {
+                    stats.increment_me_route_drop_queue_full();
+                    stats.increment_me_route_drop_queue_full_high();
                     let streak = data_route_queue_full_streak.entry(cid).or_insert(0);
                     *streak = streak.saturating_add(1);
-                    if should_close_on_queue_full_streak(*streak) {
+                    if should_close_on_queue_full_streak(*streak)
+                        || matches!(
+                            admission,
+                            AdmissionDecision::RejectSaturated
+                                | AdmissionDecision::RejectStandingFlow
+                        )
+                    {
+                        fairness.remove_flow(cid);
                         data_route_queue_full_streak.remove(&cid);
                         reg.unregister(cid).await;
                         send_close_conn(&tx, cid).await;
@@ -249,12 +363,14 @@ pub(crate) async fn reader_loop(
                 let _ = reg.route_nowait(cid, MeResponse::Close).await;
                 reg.unregister(cid).await;
                 data_route_queue_full_streak.remove(&cid);
+                fairness.remove_flow(cid);
             } else if pt == RPC_CLOSE_CONN_U32 && body.len() >= 8 {
                 let cid = u64::from_le_bytes(body[0..8].try_into().unwrap());
                 debug!(cid, "RPC_CLOSE_CONN from ME");
                 let _ = reg.route_nowait(cid, MeResponse::Close).await;
                 reg.unregister(cid).await;
                 data_route_queue_full_streak.remove(&cid);
+                fairness.remove_flow(cid);
             } else if pt == RPC_PING_U32 && body.len() >= 8 {
                 let ping_id = i64::from_le_bytes(body[0..8].try_into().unwrap());
                 trace!(ping_id, "RPC_PING -> RPC_PONG");
@@ -310,6 +426,19 @@ pub(crate) async fn reader_loop(
                     "Unknown RPC"
                 );
             }
+
+            let route_wait_ms = reader_route_data_wait_ms.load(Ordering::Relaxed);
+            drain_fairness_scheduler(
+                &mut fairness,
+                reg.as_ref(),
+                &tx,
+                &mut data_route_queue_full_streak,
+                route_wait_ms,
+                stats.as_ref(),
+            )
+            .await;
+            let current_snapshot = fairness.snapshot();
+            apply_fairness_metrics_delta(stats.as_ref(), &mut fairness_snapshot, current_snapshot);
         }
     }
 }

src/transport/middle_proxy/registry.rs

@@ -140,6 +140,10 @@ impl ConnRegistry {
         }
     }
 
+    pub fn route_channel_capacity(&self) -> usize {
+        self.route_channel_capacity
+    }
+
     #[cfg(test)]
     pub fn new() -> Self {
         Self::with_route_channel_capacity(4096)

src/transport/middle_proxy/tests/fairness_security_tests.rs

@@ -0,0 +1,185 @@
+use std::time::{Duration, Instant};
+
+use bytes::Bytes;
+
+use crate::transport::middle_proxy::fairness::{
+    AdmissionDecision, DispatchAction, DispatchFeedback, PressureState, SchedulerDecision,
+    WorkerFairnessConfig, WorkerFairnessState,
+};
+
+fn enqueue_payload(size: usize) -> Bytes {
+    Bytes::from(vec![0xAB; size])
+}
+
+#[test]
+fn fairness_rejects_when_worker_budget_is_exhausted() {
+    let now = Instant::now();
+    let mut fairness = WorkerFairnessState::new(
+        WorkerFairnessConfig {
+            max_total_queued_bytes: 1024,
+            max_flow_queued_bytes: 1024,
+            ..WorkerFairnessConfig::default()
+        },
+        now,
+    );
+
+    assert_eq!(
+        fairness.enqueue_data(1, 0, enqueue_payload(700), now),
+        AdmissionDecision::Admit
+    );
+    assert_eq!(
+        fairness.enqueue_data(2, 0, enqueue_payload(400), now),
+        AdmissionDecision::RejectWorkerCap
+    );
+
+    let snapshot = fairness.snapshot();
+    assert!(snapshot.total_queued_bytes <= 1024);
+    assert_eq!(snapshot.enqueue_rejects, 1);
+}
+
+#[test]
+fn fairness_marks_standing_queue_after_stall_and_age_threshold() {
+    let mut now = Instant::now();
+    let mut fairness = WorkerFairnessState::new(
+        WorkerFairnessConfig {
+            standing_queue_min_age: Duration::from_millis(50),
+            standing_queue_min_backlog_bytes: 256,
+            standing_stall_threshold: 1,
+            max_flow_queued_bytes: 4096,
+            max_total_queued_bytes: 4096,
+            ..WorkerFairnessConfig::default()
+        },
+        now,
+    );
+
+    assert_eq!(
+        fairness.enqueue_data(11, 0, enqueue_payload(512), now),
+        AdmissionDecision::Admit
+    );
+
+    now += Duration::from_millis(100);
+    let SchedulerDecision::Dispatch(candidate) = fairness.next_decision(now) else {
+        panic!("expected dispatch candidate");
+    };
+
+    let action = fairness.apply_dispatch_feedback(11, candidate, DispatchFeedback::QueueFull, now);
+    assert!(matches!(action, DispatchAction::Continue));
+
+    let snapshot = fairness.snapshot();
+    assert_eq!(snapshot.standing_flows, 1);
+    assert!(snapshot.backpressured_flows >= 1);
+}
+
+#[test]
+fn fairness_keeps_fast_flow_progress_under_slow_neighbor() {
+    let mut now = Instant::now();
+    let mut fairness = WorkerFairnessState::new(
+        WorkerFairnessConfig {
+            max_total_queued_bytes: 64 * 1024,
+            max_flow_queued_bytes: 32 * 1024,
+            ..WorkerFairnessConfig::default()
+        },
+        now,
+    );
+
+    for _ in 0..16 {
+        assert_eq!(
+            fairness.enqueue_data(1, 0, enqueue_payload(512), now),
+            AdmissionDecision::Admit
+        );
+        assert_eq!(
+            fairness.enqueue_data(2, 0, enqueue_payload(512), now),
+            AdmissionDecision::Admit
+        );
+    }
+
+    let mut fast_routed = 0u64;
+    for _ in 0..128 {
+        now += Duration::from_millis(5);
+        let SchedulerDecision::Dispatch(candidate) = fairness.next_decision(now) else {
+            break;
+        };
+        let cid = candidate.frame.conn_id;
+        let feedback = if cid == 2 {
+            DispatchFeedback::QueueFull
+        } else {
+            fast_routed = fast_routed.saturating_add(1);
+            DispatchFeedback::Routed
+        };
+        let _ = fairness.apply_dispatch_feedback(cid, candidate, feedback, now);
+    }
+
+    let snapshot = fairness.snapshot();
+    assert!(fast_routed > 0, "fast flow must continue making progress");
+    assert!(snapshot.total_queued_bytes <= 64 * 1024);
+}
+
+#[test]
+fn fairness_pressure_hysteresis_prevents_instant_flapping() {
+    let mut now = Instant::now();
+    let mut cfg = WorkerFairnessConfig::default();
+    cfg.max_total_queued_bytes = 4096;
+    cfg.max_flow_queued_bytes = 4096;
+    cfg.pressure.evaluate_every_rounds = 1;
+    cfg.pressure.transition_hysteresis_rounds = 3;
+    cfg.pressure.queue_ratio_pressured_pct = 40;
+    cfg.pressure.queue_ratio_shedding_pct = 60;
+    cfg.pressure.queue_ratio_saturated_pct = 80;
+
+    let mut fairness = WorkerFairnessState::new(cfg, now);
+
+    for _ in 0..4 {
+        assert_eq!(
+            fairness.enqueue_data(9, 0, enqueue_payload(900), now),
+            AdmissionDecision::Admit
+        );
+    }
+
+    for _ in 0..2 {
+        now += Duration::from_millis(1);
+        let _ = fairness.next_decision(now);
+    }
+
+    assert_eq!(
+        fairness.pressure_state(),
+        PressureState::Normal,
+        "state must not flip before hysteresis confirmations"
+    );
+}
+
+#[test]
+fn fairness_randomized_sequence_preserves_memory_bounds() {
+    let mut now = Instant::now();
+    let mut fairness = WorkerFairnessState::new(
+        WorkerFairnessConfig {
+            max_total_queued_bytes: 32 * 1024,
+            max_flow_queued_bytes: 4 * 1024,
+            ..WorkerFairnessConfig::default()
+        },
+        now,
+    );
+
+    let mut seed = 0xC0FFEE_u64;
+    for _ in 0..4096 {
+        seed ^= seed << 7;
+        seed ^= seed >> 9;
+        seed ^= seed << 8;
+        let flow = (seed % 32) + 1;
+        let size = ((seed >> 8) % 512 + 64) as usize;
+        let _ = fairness.enqueue_data(flow, 0, enqueue_payload(size), now);
+
+        now += Duration::from_millis(1);
+        if let SchedulerDecision::Dispatch(candidate) = fairness.next_decision(now) {
+            let feedback = if seed & 0x1 == 0 {
+                DispatchFeedback::Routed
+            } else {
+                DispatchFeedback::QueueFull
+            };
+            let _ =
+                fairness.apply_dispatch_feedback(candidate.frame.conn_id, candidate, feedback, now);
+        }
+
+        let snapshot = fairness.snapshot();
+        assert!(snapshot.total_queued_bytes <= 32 * 1024);
+    }
+}

src/transport/upstream.rs

@@ -279,6 +279,12 @@ pub struct UpstreamApiSummarySnapshot {
     pub shadowsocks_total: usize,
 }
 
+#[derive(Debug, Clone, Copy, Default)]
+pub struct UpstreamApiHealthSummary {
+    pub configured_total: usize,
+    pub healthy_total: usize,
+}
+
 #[derive(Debug, Clone)]
 pub struct UpstreamApiSnapshot {
     pub summary: UpstreamApiSummarySnapshot,
@@ -444,6 +450,20 @@ impl UpstreamManager {
         Some(UpstreamApiSnapshot { summary, upstreams })
     }
 
+    pub async fn api_health_summary(&self) -> UpstreamApiHealthSummary {
+        let guard = self.upstreams.read().await;
+        let mut summary = UpstreamApiHealthSummary {
+            configured_total: guard.len(),
+            healthy_total: 0,
+        };
+        for upstream in guard.iter() {
+            if upstream.healthy {
+                summary.healthy_total += 1;
+            }
+        }
+        summary
+    }
+
     fn describe_upstream(upstream_type: &UpstreamType) -> (UpstreamRouteKind, String) {
         match upstream_type {
             UpstreamType::Direct { .. } => (UpstreamRouteKind::Direct, "direct".to_string()),