Merge 4d83d02a8f into a383efcb21

Bounded Hybrid Loop + Watch + Family ArcSwap Snapshots + Health in Parallel + ArcSwap Writers + Registry Split + Endpoint on ArcSwap + New Backpressure Model + ME Decomposition

Cargo.lock

@@ -2793,7 +2793,7 @@ checksum = "7b2093cf4c8eb1e67749a6762251bc9cd836b6fc171623bd0a9d324d37af2417"
 
 [[package]]
 name = "telemt"
-version = "3.3.31"
+version = "3.3.32"
 dependencies = [
  "aes",
  "anyhow",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "telemt"
-version = "3.3.31"
+version = "3.3.32"
 edition = "2024"
 
 [features]

src/api/runtime_zero.rs

@@ -35,11 +35,14 @@ pub(super) struct RuntimeGatesData {
     pub(super) conditional_cast_enabled: bool,
     pub(super) me_runtime_ready: bool,
     pub(super) me2dc_fallback_enabled: bool,
+    pub(super) me2dc_fast_enabled: bool,
     pub(super) use_middle_proxy: bool,
     pub(super) route_mode: &'static str,
     pub(super) reroute_active: bool,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub(super) reroute_to_direct_at_epoch_secs: Option<u64>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(super) reroute_reason: Option<&'static str>,
     pub(super) startup_status: &'static str,
     pub(super) startup_stage: String,
     pub(super) startup_progress_pct: f64,
@@ -86,6 +89,7 @@ pub(super) struct EffectiveMiddleProxyLimits {
     pub(super) writer_pick_mode: &'static str,
     pub(super) writer_pick_sample_size: u8,
     pub(super) me2dc_fallback: bool,
+    pub(super) me2dc_fast: bool,
 }
 
 #[derive(Serialize)]
@@ -169,6 +173,8 @@ pub(super) async fn build_runtime_gates_data(
     let startup_summary = build_runtime_startup_summary(shared).await;
     let route_state = shared.route_runtime.snapshot();
     let route_mode = route_state.mode.as_str();
+    let fast_fallback_enabled =
+        cfg.general.use_middle_proxy && cfg.general.me2dc_fallback && cfg.general.me2dc_fast;
     let reroute_active = cfg.general.use_middle_proxy
         && cfg.general.me2dc_fallback
         && matches!(route_state.mode, RelayRouteMode::Direct);
@@ -177,6 +183,15 @@ pub(super) async fn build_runtime_gates_data(
     } else {
         None
     };
+    let reroute_reason = if reroute_active {
+        if fast_fallback_enabled {
+            Some("fast_not_ready_fallback")
+        } else {
+            Some("strict_grace_fallback")
+        }
+    } else {
+        None
+    };
     let me_runtime_ready = if !cfg.general.use_middle_proxy {
         true
     } else {
@@ -194,10 +209,12 @@ pub(super) async fn build_runtime_gates_data(
         conditional_cast_enabled: cfg.general.use_middle_proxy,
         me_runtime_ready,
         me2dc_fallback_enabled: cfg.general.me2dc_fallback,
+        me2dc_fast_enabled: fast_fallback_enabled,
         use_middle_proxy: cfg.general.use_middle_proxy,
         route_mode,
         reroute_active,
         reroute_to_direct_at_epoch_secs,
+        reroute_reason,
         startup_status: startup_summary.status,
         startup_stage: startup_summary.stage,
         startup_progress_pct: startup_summary.progress_pct,
@@ -263,6 +280,7 @@ pub(super) fn build_limits_effective_data(cfg: &ProxyConfig) -> EffectiveLimitsD
             writer_pick_mode: me_writer_pick_mode_label(cfg.general.me_writer_pick_mode),
             writer_pick_sample_size: cfg.general.me_writer_pick_sample_size,
             me2dc_fallback: cfg.general.me2dc_fallback,
+            me2dc_fast: cfg.general.me2dc_fast,
         },
         user_ip_policy: EffectiveUserIpPolicyLimits {
             global_each: cfg.access.user_max_unique_ips_global_each,

src/config/defaults.rs

@@ -273,6 +273,10 @@ pub(crate) fn default_me2dc_fallback() -> bool {
     true
 }
 
+pub(crate) fn default_me2dc_fast() -> bool {
+    false
+}
+
 pub(crate) fn default_keepalive_interval() -> u64 {
     8
 }

src/config/hot_reload.rs

@@ -651,6 +651,9 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
     }
     if old.general.me_route_no_writer_mode != new.general.me_route_no_writer_mode
         || old.general.me_route_no_writer_wait_ms != new.general.me_route_no_writer_wait_ms
+        || old.general.me_route_hybrid_max_wait_ms != new.general.me_route_hybrid_max_wait_ms
+        || old.general.me_route_blocking_send_timeout_ms
+            != new.general.me_route_blocking_send_timeout_ms
         || old.general.me_route_inline_recovery_attempts
             != new.general.me_route_inline_recovery_attempts
         || old.general.me_route_inline_recovery_wait_ms
@@ -669,9 +672,11 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
         warned = true;
         warn!("config reload: general.me_init_retry_attempts changed; restart required");
     }
-    if old.general.me2dc_fallback != new.general.me2dc_fallback {
+    if old.general.me2dc_fallback != new.general.me2dc_fallback
+        || old.general.me2dc_fast != new.general.me2dc_fast
+    {
         warned = true;
-        warn!("config reload: general.me2dc_fallback changed; restart required");
+        warn!("config reload: general.me2dc_fallback/me2dc_fast changed; restart required");
     }
     if old.general.proxy_config_v4_cache_path != new.general.proxy_config_v4_cache_path
         || old.general.proxy_config_v6_cache_path != new.general.proxy_config_v6_cache_path

src/config/load.rs

@@ -346,6 +346,12 @@ impl ProxyConfig {
             ));
         }
 
+        if config.timeouts.tg_connect == 0 {
+            return Err(ProxyError::Config(
+                "timeouts.tg_connect must be > 0".to_string(),
+            ));
+        }
+
         if config.general.upstream_unhealthy_fail_threshold == 0 {
             return Err(ProxyError::Config(
                 "general.upstream_unhealthy_fail_threshold must be > 0".to_string(),
@@ -1217,6 +1223,7 @@ mod tests {
             default_me_init_retry_attempts()
         );
         assert_eq!(cfg.general.me2dc_fallback, default_me2dc_fallback());
+        assert_eq!(cfg.general.me2dc_fast, default_me2dc_fast());
         assert_eq!(
             cfg.general.proxy_config_v4_cache_path,
             default_proxy_config_v4_cache_path()
@@ -1356,6 +1363,7 @@ mod tests {
             default_me_init_retry_attempts()
         );
         assert_eq!(general.me2dc_fallback, default_me2dc_fallback());
+        assert_eq!(general.me2dc_fast, default_me2dc_fast());
         assert_eq!(
             general.proxy_config_v4_cache_path,
             default_proxy_config_v4_cache_path()
@@ -1905,6 +1913,26 @@ mod tests {
         let _ = std::fs::remove_file(path);
     }
 
+    #[test]
+    fn tg_connect_zero_is_rejected() {
+        let toml = r#"
+            [timeouts]
+            tg_connect = 0
+
+            [censorship]
+            tls_domain = "example.com"
+
+            [access.users]
+            user = "00000000000000000000000000000000"
+        "#;
+        let dir = std::env::temp_dir();
+        let path = dir.join("telemt_tg_connect_zero_test.toml");
+        std::fs::write(&path, toml).unwrap();
+        let err = ProxyConfig::load(&path).unwrap_err().to_string();
+        assert!(err.contains("timeouts.tg_connect must be > 0"));
+        let _ = std::fs::remove_file(path);
+    }
+
     #[test]
     fn rpc_proxy_req_every_out_of_range_is_rejected() {
         let toml = r#"

src/config/types.rs

@@ -429,6 +429,11 @@ pub struct GeneralConfig {
     #[serde(default = "default_me2dc_fallback")]
     pub me2dc_fallback: bool,
 
+    /// Fast ME->Direct fallback mode for new sessions.
+    /// Active only when both `use_middle_proxy=true` and `me2dc_fallback=true`.
+    #[serde(default = "default_me2dc_fast")]
+    pub me2dc_fast: bool,
+
     /// Enable ME keepalive padding frames.
     #[serde(default = "default_true")]
     pub me_keepalive_enabled: bool,
@@ -939,6 +944,7 @@ impl Default for GeneralConfig {
             middle_proxy_warm_standby: default_middle_proxy_warm_standby(),
             me_init_retry_attempts: default_me_init_retry_attempts(),
             me2dc_fallback: default_me2dc_fallback(),
+            me2dc_fast: default_me2dc_fast(),
             me_keepalive_enabled: default_true(),
             me_keepalive_interval_secs: default_keepalive_interval(),
             me_keepalive_jitter_secs: default_keepalive_jitter(),

src/maestro/admission.rs

@@ -21,10 +21,29 @@ pub(crate) async fn configure_admission_gate(
     if config.general.use_middle_proxy {
         if let Some(pool) = me_pool.as_ref() {
             let initial_ready = pool.admission_ready_conditional_cast().await;
-            admission_tx.send_replace(initial_ready);
-            let _ = route_runtime.set_mode(RelayRouteMode::Middle);
+            let mut fallback_enabled = config.general.me2dc_fallback;
+            let mut fast_fallback_enabled = fallback_enabled && config.general.me2dc_fast;
+            let (initial_gate_open, initial_route_mode, initial_fallback_reason) = if initial_ready
+            {
+                (true, RelayRouteMode::Middle, None)
+            } else if fast_fallback_enabled {
+                (
+                    true,
+                    RelayRouteMode::Direct,
+                    Some("fast_not_ready_fallback"),
+                )
+            } else {
+                (false, RelayRouteMode::Middle, None)
+            };
+            admission_tx.send_replace(initial_gate_open);
+            let _ = route_runtime.set_mode(initial_route_mode);
             if initial_ready {
                 info!("Conditional-admission gate: open / ME pool READY");
+            } else if let Some(reason) = initial_fallback_reason {
+                warn!(
+                    fallback_reason = reason,
+                    "Conditional-admission gate opened in ME fast fallback mode"
+                );
             } else {
                 warn!("Conditional-admission gate: closed / ME pool is NOT ready)");
             }
@@ -34,10 +53,9 @@ pub(crate) async fn configure_admission_gate(
             let route_runtime_gate = route_runtime.clone();
             let mut config_rx_gate = config_rx.clone();
             let mut admission_poll_ms = config.general.me_admission_poll_ms.max(1);
-            let mut fallback_enabled = config.general.me2dc_fallback;
             tokio::spawn(async move {
-                let mut gate_open = initial_ready;
-                let mut route_mode = RelayRouteMode::Middle;
+                let mut gate_open = initial_gate_open;
+                let mut route_mode = initial_route_mode;
                 let mut ready_observed = initial_ready;
                 let mut not_ready_since = if initial_ready {
                     None
@@ -53,16 +71,23 @@ pub(crate) async fn configure_admission_gate(
                             let cfg = config_rx_gate.borrow_and_update().clone();
                             admission_poll_ms = cfg.general.me_admission_poll_ms.max(1);
                             fallback_enabled = cfg.general.me2dc_fallback;
+                            fast_fallback_enabled = cfg.general.me2dc_fallback && cfg.general.me2dc_fast;
                             continue;
                         }
                         _ = tokio::time::sleep(Duration::from_millis(admission_poll_ms)) => {}
                     }
                     let ready = pool_for_gate.admission_ready_conditional_cast().await;
                     let now = Instant::now();
-                    let (next_gate_open, next_route_mode, next_fallback_active) = if ready {
+                    let (next_gate_open, next_route_mode, next_fallback_reason) = if ready {
                         ready_observed = true;
                         not_ready_since = None;
-                        (true, RelayRouteMode::Middle, false)
+                        (true, RelayRouteMode::Middle, None)
+                    } else if fast_fallback_enabled {
+                        (
+                            true,
+                            RelayRouteMode::Direct,
+                            Some("fast_not_ready_fallback"),
+                        )
                     } else {
                         let not_ready_started_at = *not_ready_since.get_or_insert(now);
                         let not_ready_for = now.saturating_duration_since(not_ready_started_at);
@@ -72,11 +97,12 @@ pub(crate) async fn configure_admission_gate(
                             STARTUP_FALLBACK_AFTER
                         };
                         if fallback_enabled && not_ready_for > fallback_after {
-                            (true, RelayRouteMode::Direct, true)
+                            (true, RelayRouteMode::Direct, Some("strict_grace_fallback"))
                         } else {
-                            (false, RelayRouteMode::Middle, false)
+                            (false, RelayRouteMode::Middle, None)
                         }
                     };
+                    let next_fallback_active = next_fallback_reason.is_some();
 
                     if next_route_mode != route_mode {
                         route_mode = next_route_mode;
@@ -88,17 +114,28 @@ pub(crate) async fn configure_admission_gate(
                                     "Middle-End routing restored for new sessions"
                                 );
                             } else {
-                                let fallback_after = if ready_observed {
-                                    RUNTIME_FALLBACK_AFTER
+                                let fallback_reason = next_fallback_reason.unwrap_or("unknown");
+                                if fallback_reason == "strict_grace_fallback" {
+                                    let fallback_after = if ready_observed {
+                                        RUNTIME_FALLBACK_AFTER
+                                    } else {
+                                        STARTUP_FALLBACK_AFTER
+                                    };
+                                    warn!(
+                                        target_mode = route_mode.as_str(),
+                                        cutover_generation = snapshot.generation,
+                                        grace_secs = fallback_after.as_secs(),
+                                        fallback_reason,
+                                        "ME pool stayed not-ready beyond grace; routing new sessions via Direct-DC"
+                                    );
                                 } else {
-                                    STARTUP_FALLBACK_AFTER
-                                };
-                                warn!(
-                                    target_mode = route_mode.as_str(),
-                                    cutover_generation = snapshot.generation,
-                                    grace_secs = fallback_after.as_secs(),
-                                    "ME pool stayed not-ready beyond grace; routing new sessions via Direct-DC"
-                                );
+                                    warn!(
+                                        target_mode = route_mode.as_str(),
+                                        cutover_generation = snapshot.generation,
+                                        fallback_reason,
+                                        "ME pool not-ready; routing new sessions via Direct-DC (fast mode)"
+                                    );
+                                }
                             }
                         }
                     }
@@ -108,7 +145,10 @@ pub(crate) async fn configure_admission_gate(
                         admission_tx_gate.send_replace(gate_open);
                         if gate_open {
                             if next_fallback_active {
-                                warn!("Conditional-admission gate opened in ME fallback mode");
+                                warn!(
+                                    fallback_reason = next_fallback_reason.unwrap_or("unknown"),
+                                    "Conditional-admission gate opened in ME fallback mode"
+                                );
                             } else {
                                 info!("Conditional-admission gate opened / ME pool READY");
                             }

src/maestro/me_startup.rs

@@ -277,6 +277,8 @@ pub(crate) async fn initialize_me_pool(
                     config.general.me_warn_rate_limit_ms,
                     config.general.me_route_no_writer_mode,
                     config.general.me_route_no_writer_wait_ms,
+                    config.general.me_route_hybrid_max_wait_ms,
+                    config.general.me_route_blocking_send_timeout_ms,
                     config.general.me_route_inline_recovery_attempts,
                     config.general.me_route_inline_recovery_wait_ms,
                 );

src/maestro/mod.rs

@@ -115,15 +115,13 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
                 );
                 std::process::exit(1);
             }
-        } else {
-            if let Err(e) = std::fs::create_dir_all(data_path) {
-                eprintln!(
-                    "[telemt] Can't create data_path {}: {}",
-                    data_path.display(),
-                    e
-                );
-                std::process::exit(1);
-            }
+        } else if let Err(e) = std::fs::create_dir_all(data_path) {
+            eprintln!(
+                "[telemt] Can't create data_path {}: {}",
+                data_path.display(),
+                e
+            );
+            std::process::exit(1);
         }
 
         if let Err(e) = std::env::set_current_dir(data_path) {
@@ -225,6 +223,7 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
         config.general.upstream_connect_retry_attempts,
         config.general.upstream_connect_retry_backoff_ms,
         config.general.upstream_connect_budget_ms,
+        config.timeouts.tg_connect,
         config.general.upstream_unhealthy_fail_threshold,
         config.general.upstream_connect_failfast_hard_errors,
         stats.clone(),

src/metrics.rs

@@ -1558,6 +1558,40 @@ async fn render_metrics(stats: &Stats, config: &ProxyConfig, ip_tracker: &UserIp
             0
         }
     );
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_endpoint_quarantine_unexpected_total ME endpoint quarantines caused by unexpected writer removals"
+    );
+    let _ = writeln!(
+        out,
+        "# TYPE telemt_me_endpoint_quarantine_unexpected_total counter"
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_endpoint_quarantine_unexpected_total {}",
+        if me_allows_normal {
+            stats.get_me_endpoint_quarantine_unexpected_total()
+        } else {
+            0
+        }
+    );
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_endpoint_quarantine_draining_suppressed_total Draining writer removals that skipped endpoint quarantine"
+    );
+    let _ = writeln!(
+        out,
+        "# TYPE telemt_me_endpoint_quarantine_draining_suppressed_total counter"
+    );
+    let _ = writeln!(
+        out,
+        "telemt_me_endpoint_quarantine_draining_suppressed_total {}",
+        if me_allows_normal {
+            stats.get_me_endpoint_quarantine_draining_suppressed_total()
+        } else {
+            0
+        }
+    );
 
     let _ = writeln!(
         out,
@@ -2318,6 +2352,20 @@ async fn render_metrics(stats: &Stats, config: &ProxyConfig, ip_tracker: &UserIp
             0
         }
     );
+    let _ = writeln!(
+        out,
+        "# HELP telemt_me_hybrid_timeout_total ME hybrid route timeouts after bounded retry window"
+    );
+    let _ = writeln!(out, "# TYPE telemt_me_hybrid_timeout_total counter");
+    let _ = writeln!(
+        out,
+        "telemt_me_hybrid_timeout_total {}",
+        if me_allows_normal {
+            stats.get_me_hybrid_timeout_total()
+        } else {
+            0
+        }
+    );
     let _ = writeln!(
         out,
         "# HELP telemt_me_async_recovery_trigger_total Async ME recovery trigger attempts from route path"
@@ -2608,6 +2656,9 @@ mod tests {
         stats.increment_me_d2c_write_mode(crate::stats::MeD2cWriteMode::Coalesced);
         stats.increment_me_d2c_quota_reject_total(crate::stats::MeD2cQuotaRejectStage::PostWrite);
         stats.observe_me_d2c_frame_buf_shrink(4096);
+        stats.increment_me_endpoint_quarantine_total();
+        stats.increment_me_endpoint_quarantine_unexpected_total();
+        stats.increment_me_endpoint_quarantine_draining_suppressed_total();
         stats.increment_user_connects("alice");
         stats.increment_user_curr_connects("alice");
         stats.add_user_octets_from("alice", 1024);
@@ -2658,6 +2709,9 @@ mod tests {
         assert!(output.contains("telemt_me_d2c_quota_reject_total{stage=\"post_write\"} 1"));
         assert!(output.contains("telemt_me_d2c_frame_buf_shrink_total 1"));
         assert!(output.contains("telemt_me_d2c_frame_buf_shrink_bytes_total 4096"));
+        assert!(output.contains("telemt_me_endpoint_quarantine_total 1"));
+        assert!(output.contains("telemt_me_endpoint_quarantine_unexpected_total 1"));
+        assert!(output.contains("telemt_me_endpoint_quarantine_draining_suppressed_total 1"));
         assert!(output.contains("telemt_user_connections_total{user=\"alice\"} 1"));
         assert!(output.contains("telemt_user_connections_current{user=\"alice\"} 1"));
         assert!(output.contains("telemt_user_octets_from_client{user=\"alice\"} 1024"));
@@ -2724,6 +2778,12 @@ mod tests {
         assert!(output.contains("# TYPE telemt_me_d2c_write_mode_total counter"));
         assert!(output.contains("# TYPE telemt_me_d2c_batch_frames_bucket_total counter"));
         assert!(output.contains("# TYPE telemt_me_d2c_flush_duration_us_bucket_total counter"));
+        assert!(output.contains("# TYPE telemt_me_endpoint_quarantine_total counter"));
+        assert!(output.contains("# TYPE telemt_me_endpoint_quarantine_unexpected_total counter"));
+        assert!(
+            output
+                .contains("# TYPE telemt_me_endpoint_quarantine_draining_suppressed_total counter")
+        );
         assert!(output.contains("# TYPE telemt_me_writer_removed_total counter"));
         assert!(
             output

src/proxy/middle_relay.rs

@@ -4,7 +4,7 @@ use std::collections::{BTreeSet, HashMap};
 use std::future::Future;
 use std::hash::{BuildHasher, Hash};
 use std::net::{IpAddr, SocketAddr};
-use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
+use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::{Arc, Mutex, OnceLock};
 use std::time::{Duration, Instant};
 
@@ -36,7 +36,6 @@ enum C2MeCommand {
 
 const DESYNC_DEDUP_WINDOW: Duration = Duration::from_secs(60);
 const DESYNC_DEDUP_MAX_ENTRIES: usize = 65_536;
-const DESYNC_DEDUP_PRUNE_SCAN_LIMIT: usize = 1024;
 const DESYNC_FULL_CACHE_EMIT_MIN_INTERVAL: Duration = Duration::from_millis(1000);
 const DESYNC_ERROR_CLASS: &str = "frame_too_large_crypto_desync";
 const C2ME_CHANNEL_CAPACITY_FALLBACK: usize = 128;
@@ -46,10 +45,6 @@ const RELAY_IDLE_IO_POLL_MAX: Duration = Duration::from_secs(1);
 const TINY_FRAME_DEBT_PER_TINY: u32 = 8;
 const TINY_FRAME_DEBT_LIMIT: u32 = 512;
 #[cfg(test)]
-const C2ME_SEND_TIMEOUT: Duration = Duration::from_millis(50);
-#[cfg(not(test))]
-const C2ME_SEND_TIMEOUT: Duration = Duration::from_secs(5);
-#[cfg(test)]
 const RELAY_TEST_STEP_TIMEOUT: Duration = Duration::from_secs(1);
 const ME_D2C_FLUSH_BATCH_MAX_FRAMES_MIN: usize = 1;
 const ME_D2C_FLUSH_BATCH_MAX_BYTES_MIN: usize = 4096;
@@ -57,12 +52,21 @@ const ME_D2C_FRAME_BUF_SHRINK_HYSTERESIS_FACTOR: usize = 2;
 const ME_D2C_SINGLE_WRITE_COALESCE_MAX_BYTES: usize = 128 * 1024;
 const QUOTA_RESERVE_SPIN_RETRIES: usize = 32;
 static DESYNC_DEDUP: OnceLock<DashMap<u64, Instant>> = OnceLock::new();
+static DESYNC_DEDUP_PREVIOUS: OnceLock<DashMap<u64, Instant>> = OnceLock::new();
 static DESYNC_HASHER: OnceLock<RandomState> = OnceLock::new();
 static DESYNC_FULL_CACHE_LAST_EMIT_AT: OnceLock<Mutex<Option<Instant>>> = OnceLock::new();
-static DESYNC_DEDUP_EVER_SATURATED: OnceLock<AtomicBool> = OnceLock::new();
+static DESYNC_DEDUP_ROTATION_STATE: OnceLock<Mutex<DesyncDedupRotationState>> = OnceLock::new();
+// Invariant for async callers:
+// this std::sync::Mutex is allowed only because critical sections are short,
+// synchronous, and MUST never cross an `.await`.
 static RELAY_IDLE_CANDIDATE_REGISTRY: OnceLock<Mutex<RelayIdleCandidateRegistry>> = OnceLock::new();
 static RELAY_IDLE_MARK_SEQ: AtomicU64 = AtomicU64::new(0);
 
+#[derive(Default)]
+struct DesyncDedupRotationState {
+    current_started_at: Option<Instant>,
+}
+
 struct RelayForensicsState {
     trace_id: u64,
     conn_id: u64,
@@ -95,6 +99,7 @@ fn relay_idle_candidate_registry() -> &'static Mutex<RelayIdleCandidateRegistry>
 
 fn relay_idle_candidate_registry_lock() -> std::sync::MutexGuard<'static, RelayIdleCandidateRegistry>
 {
+    // Keep lock scope narrow and synchronous: callers must drop guard before any `.await`.
     let registry = relay_idle_candidate_registry();
     match registry.lock() {
         Ok(guard) => guard,
@@ -312,64 +317,76 @@ fn should_emit_full_desync(key: u64, all_full: bool, now: Instant) -> bool {
         return true;
     }
 
-    let dedup = DESYNC_DEDUP.get_or_init(DashMap::new);
-    let saturated_before = dedup.len() >= DESYNC_DEDUP_MAX_ENTRIES;
-    let ever_saturated = DESYNC_DEDUP_EVER_SATURATED.get_or_init(|| AtomicBool::new(false));
-    if saturated_before {
-        ever_saturated.store(true, Ordering::Relaxed);
-    }
+    let dedup_current = DESYNC_DEDUP.get_or_init(DashMap::new);
+    let dedup_previous = DESYNC_DEDUP_PREVIOUS.get_or_init(DashMap::new);
+    let rotation_state =
+        DESYNC_DEDUP_ROTATION_STATE.get_or_init(|| Mutex::new(DesyncDedupRotationState::default()));
 
-    if let Some(mut seen_at) = dedup.get_mut(&key) {
-        if now.duration_since(*seen_at) >= DESYNC_DEDUP_WINDOW {
-            *seen_at = now;
-            return true;
+    let mut state = match rotation_state.lock() {
+        Ok(guard) => guard,
+        Err(poisoned) => {
+            let mut guard = poisoned.into_inner();
+            *guard = DesyncDedupRotationState::default();
+            rotation_state.clear_poison();
+            guard
         }
-        return false;
-    }
-
-    if dedup.len() >= DESYNC_DEDUP_MAX_ENTRIES {
-        let mut stale_keys = Vec::new();
-        let mut oldest_candidate: Option<(u64, Instant)> = None;
-        for entry in dedup.iter().take(DESYNC_DEDUP_PRUNE_SCAN_LIMIT) {
-            let key = *entry.key();
-            let seen_at = *entry.value();
-
-            match oldest_candidate {
-                Some((_, oldest_seen)) if seen_at >= oldest_seen => {}
-                _ => oldest_candidate = Some((key, seen_at)),
-            }
-
-            if now.duration_since(seen_at) >= DESYNC_DEDUP_WINDOW {
-                stale_keys.push(*entry.key());
-            }
-        }
-        for stale_key in stale_keys {
-            dedup.remove(&stale_key);
-        }
-        if dedup.len() >= DESYNC_DEDUP_MAX_ENTRIES {
-            let Some((evict_key, _)) = oldest_candidate else {
-                return false;
-            };
-            dedup.remove(&evict_key);
-            dedup.insert(key, now);
-            return should_emit_full_desync_full_cache(now);
-        }
-    }
-
-    dedup.insert(key, now);
-    let saturated_after = dedup.len() >= DESYNC_DEDUP_MAX_ENTRIES;
-    // Preserve the first sequential insert that reaches capacity as a normal
-    // emit, while still gating concurrent newcomer churn after the cache has
-    // ever been observed at saturation.
-    let was_ever_saturated = if saturated_after {
-        ever_saturated.swap(true, Ordering::Relaxed)
-    } else {
-        ever_saturated.load(Ordering::Relaxed)
     };
 
-    if saturated_before || (saturated_after && was_ever_saturated) {
+    let rotate_now = match state.current_started_at {
+        Some(current_started_at) => match now.checked_duration_since(current_started_at) {
+            Some(elapsed) => elapsed >= DESYNC_DEDUP_WINDOW,
+            None => true,
+        },
+        None => true,
+    };
+    if rotate_now {
+        dedup_previous.clear();
+        for entry in dedup_current.iter() {
+            dedup_previous.insert(*entry.key(), *entry.value());
+        }
+        dedup_current.clear();
+        state.current_started_at = Some(now);
+    }
+
+    if let Some(seen_at) = dedup_current.get(&key).map(|entry| *entry.value()) {
+        let within_window = match now.checked_duration_since(seen_at) {
+            Some(elapsed) => elapsed < DESYNC_DEDUP_WINDOW,
+            None => true,
+        };
+        if within_window {
+            return false;
+        }
+        dedup_current.insert(key, now);
+        return true;
+    }
+
+    if let Some(seen_at) = dedup_previous.get(&key).map(|entry| *entry.value()) {
+        let within_window = match now.checked_duration_since(seen_at) {
+            Some(elapsed) => elapsed < DESYNC_DEDUP_WINDOW,
+            None => true,
+        };
+        if within_window {
+            // Keep the original timestamp when promoting from previous bucket,
+            // so dedup expiry remains tied to first-seen time.
+            dedup_current.insert(key, seen_at);
+            return false;
+        }
+        dedup_previous.remove(&key);
+    }
+
+    if dedup_current.len() >= DESYNC_DEDUP_MAX_ENTRIES {
+        // Bounded eviction path: rotate buckets instead of scanning/evicting
+        // arbitrary entries from a saturated single map.
+        dedup_previous.clear();
+        for entry in dedup_current.iter() {
+            dedup_previous.insert(*entry.key(), *entry.value());
+        }
+        dedup_current.clear();
+        state.current_started_at = Some(now);
+        dedup_current.insert(key, now);
         should_emit_full_desync_full_cache(now)
     } else {
+        dedup_current.insert(key, now);
         true
     }
 }
@@ -405,8 +422,20 @@ fn clear_desync_dedup_for_testing() {
     if let Some(dedup) = DESYNC_DEDUP.get() {
         dedup.clear();
     }
-    if let Some(ever_saturated) = DESYNC_DEDUP_EVER_SATURATED.get() {
-        ever_saturated.store(false, Ordering::Relaxed);
+    if let Some(dedup_previous) = DESYNC_DEDUP_PREVIOUS.get() {
+        dedup_previous.clear();
+    }
+    if let Some(rotation_state) = DESYNC_DEDUP_ROTATION_STATE.get() {
+        match rotation_state.lock() {
+            Ok(mut guard) => {
+                *guard = DesyncDedupRotationState::default();
+            }
+            Err(poisoned) => {
+                let mut guard = poisoned.into_inner();
+                *guard = DesyncDedupRotationState::default();
+                rotation_state.clear_poison();
+            }
+        }
     }
     if let Some(last_emit_at) = DESYNC_FULL_CACHE_LAST_EMIT_AT.get() {
         match last_emit_at.lock() {
@@ -615,6 +644,7 @@ pub(crate) fn relay_idle_pressure_test_scope() -> std::sync::MutexGuard<'static,
 async fn enqueue_c2me_command(
     tx: &mpsc::Sender<C2MeCommand>,
     cmd: C2MeCommand,
+    send_timeout: Option<Duration>,
 ) -> std::result::Result<(), mpsc::error::SendError<C2MeCommand>> {
     match tx.try_send(cmd) {
         Ok(()) => Ok(()),
@@ -625,12 +655,18 @@ async fn enqueue_c2me_command(
             if tx.capacity() <= C2ME_SOFT_PRESSURE_MIN_FREE_SLOTS {
                 tokio::task::yield_now().await;
             }
-            match timeout(C2ME_SEND_TIMEOUT, tx.reserve()).await {
-                Ok(Ok(permit)) => {
+            let reserve_result = match send_timeout {
+                Some(send_timeout) => match timeout(send_timeout, tx.reserve()).await {
+                    Ok(result) => result,
+                    Err(_) => return Err(mpsc::error::SendError(cmd)),
+                },
+                None => tx.reserve().await,
+            };
+            match reserve_result {
+                Ok(permit) => {
                     permit.send(cmd);
                     Ok(())
                 }
-                Ok(Err(_)) => Err(mpsc::error::SendError(cmd)),
                 Err(_) => Err(mpsc::error::SendError(cmd)),
             }
         }
@@ -756,6 +792,10 @@ where
         .general
         .me_c2me_channel_capacity
         .max(C2ME_CHANNEL_CAPACITY_FALLBACK);
+    let c2me_send_timeout = match config.general.me_c2me_send_timeout_ms {
+        0 => None,
+        timeout_ms => Some(Duration::from_millis(timeout_ms)),
+    };
     let (c2me_tx, mut c2me_rx) = mpsc::channel::<C2MeCommand>(c2me_channel_capacity);
     let me_pool_c2me = me_pool.clone();
     let c2me_sender = tokio::spawn(async move {
@@ -1132,7 +1172,7 @@ where
                 user = %user,
                 "Middle-relay pressure eviction for idle-candidate session"
             );
-            let _ = enqueue_c2me_command(&c2me_tx, C2MeCommand::Close).await;
+            let _ = enqueue_c2me_command(&c2me_tx, C2MeCommand::Close, c2me_send_timeout).await;
             main_result = Err(ProxyError::Proxy(
                 "middle-relay session evicted under pressure (idle-candidate)".to_string(),
             ));
@@ -1151,7 +1191,7 @@ where
                 "Cutover affected middle session, closing client connection"
             );
             tokio::time::sleep(delay).await;
-            let _ = enqueue_c2me_command(&c2me_tx, C2MeCommand::Close).await;
+            let _ = enqueue_c2me_command(&c2me_tx, C2MeCommand::Close, c2me_send_timeout).await;
             main_result = Err(ProxyError::Proxy(ROUTE_SWITCH_ERROR_MSG.to_string()));
             break;
         }
@@ -1209,8 +1249,12 @@ where
                             flags |= RPC_FLAG_NOT_ENCRYPTED;
                         }
                         // Keep client read loop lightweight: route heavy ME send path via a dedicated task.
-                        if enqueue_c2me_command(&c2me_tx, C2MeCommand::Data { payload, flags })
-                            .await
+                        if enqueue_c2me_command(
+                            &c2me_tx,
+                            C2MeCommand::Data { payload, flags },
+                            c2me_send_timeout,
+                        )
+                        .await
                             .is_err()
                         {
                             main_result = Err(ProxyError::Proxy("ME sender channel closed".into()));
@@ -1220,7 +1264,9 @@ where
                     Ok(None) => {
                         debug!(conn_id, "Client EOF");
                         client_closed = true;
-                        let _ = enqueue_c2me_command(&c2me_tx, C2MeCommand::Close).await;
+                        let _ =
+                            enqueue_c2me_command(&c2me_tx, C2MeCommand::Close, c2me_send_timeout)
+                                .await;
                         break;
                     }
                     Err(e) => {

src/proxy/tests/middle_relay_stub_completion_security_tests.rs

@@ -126,6 +126,7 @@ async fn c2me_channel_full_path_yields_then_sends() {
                 payload: make_pooled_payload(&[0xBB, 0xCC]),
                 flags: 2,
             },
+            None,
         )
         .await
     });

src/stats/mod.rs

@@ -128,6 +128,8 @@ pub struct Stats {
     me_crc_mismatch: AtomicU64,
     me_seq_mismatch: AtomicU64,
     me_endpoint_quarantine_total: AtomicU64,
+    me_endpoint_quarantine_unexpected_total: AtomicU64,
+    me_endpoint_quarantine_draining_suppressed_total: AtomicU64,
     me_kdf_drift_total: AtomicU64,
     me_kdf_port_only_drift_total: AtomicU64,
     me_hardswap_pending_reuse_total: AtomicU64,
@@ -234,6 +236,7 @@ pub struct Stats {
     me_writer_restored_same_endpoint_total: AtomicU64,
     me_writer_restored_fallback_total: AtomicU64,
     me_no_writer_failfast_total: AtomicU64,
+    me_hybrid_timeout_total: AtomicU64,
     me_async_recovery_trigger_total: AtomicU64,
     me_inline_recovery_total: AtomicU64,
     ip_reservation_rollback_tcp_limit_total: AtomicU64,
@@ -1203,6 +1206,11 @@ impl Stats {
                 .fetch_add(1, Ordering::Relaxed);
         }
     }
+    pub fn increment_me_hybrid_timeout_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_hybrid_timeout_total.fetch_add(1, Ordering::Relaxed);
+        }
+    }
     pub fn increment_me_async_recovery_trigger_total(&self) {
         if self.telemetry_me_allows_normal() {
             self.me_async_recovery_trigger_total
@@ -1245,6 +1253,18 @@ impl Stats {
                 .fetch_add(1, Ordering::Relaxed);
         }
     }
+    pub fn increment_me_endpoint_quarantine_unexpected_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_endpoint_quarantine_unexpected_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
+    pub fn increment_me_endpoint_quarantine_draining_suppressed_total(&self) {
+        if self.telemetry_me_allows_normal() {
+            self.me_endpoint_quarantine_draining_suppressed_total
+                .fetch_add(1, Ordering::Relaxed);
+        }
+    }
     pub fn increment_me_kdf_drift_total(&self) {
         if self.telemetry_me_allows_normal() {
             self.me_kdf_drift_total.fetch_add(1, Ordering::Relaxed);
@@ -1497,6 +1517,14 @@ impl Stats {
     pub fn get_me_endpoint_quarantine_total(&self) -> u64 {
         self.me_endpoint_quarantine_total.load(Ordering::Relaxed)
     }
+    pub fn get_me_endpoint_quarantine_unexpected_total(&self) -> u64 {
+        self.me_endpoint_quarantine_unexpected_total
+            .load(Ordering::Relaxed)
+    }
+    pub fn get_me_endpoint_quarantine_draining_suppressed_total(&self) -> u64 {
+        self.me_endpoint_quarantine_draining_suppressed_total
+            .load(Ordering::Relaxed)
+    }
     pub fn get_me_kdf_drift_total(&self) -> u64 {
         self.me_kdf_drift_total.load(Ordering::Relaxed)
     }
@@ -1876,6 +1904,9 @@ impl Stats {
     pub fn get_me_no_writer_failfast_total(&self) -> u64 {
         self.me_no_writer_failfast_total.load(Ordering::Relaxed)
     }
+    pub fn get_me_hybrid_timeout_total(&self) -> u64 {
+        self.me_hybrid_timeout_total.load(Ordering::Relaxed)
+    }
     pub fn get_me_async_recovery_trigger_total(&self) -> u64 {
         self.me_async_recovery_trigger_total.load(Ordering::Relaxed)
     }

src/tls_front/fetcher.rs

@@ -244,10 +244,9 @@ fn order_profiles(
         if let Some(pos) = ordered
             .iter()
             .position(|profile| *profile == cached.profile)
+            && pos != 0
         {
-            if pos != 0 {
-                ordered.swap(0, pos);
-            }
+            ordered.swap(0, pos);
         }
     }
 

src/transport/middle_proxy/config_updater.rs

@@ -314,53 +314,6 @@ async fn run_update_cycle(
     reinit_tx: &mpsc::Sender<MeReinitTrigger>,
 ) {
     let upstream = pool.upstream.clone();
-    pool.update_runtime_reinit_policy(
-        cfg.general.hardswap,
-        cfg.general.me_pool_drain_ttl_secs,
-        cfg.general.me_instadrain,
-        cfg.general.me_pool_drain_threshold,
-        cfg.general.me_pool_drain_soft_evict_enabled,
-        cfg.general.me_pool_drain_soft_evict_grace_secs,
-        cfg.general.me_pool_drain_soft_evict_per_writer,
-        cfg.general.me_pool_drain_soft_evict_budget_per_core,
-        cfg.general.me_pool_drain_soft_evict_cooldown_ms,
-        cfg.general.effective_me_pool_force_close_secs(),
-        cfg.general.me_pool_min_fresh_ratio,
-        cfg.general.me_hardswap_warmup_delay_min_ms,
-        cfg.general.me_hardswap_warmup_delay_max_ms,
-        cfg.general.me_hardswap_warmup_extra_passes,
-        cfg.general.me_hardswap_warmup_pass_backoff_base_ms,
-        cfg.general.me_bind_stale_mode,
-        cfg.general.me_bind_stale_ttl_secs,
-        cfg.general.me_secret_atomic_snapshot,
-        cfg.general.me_deterministic_writer_sort,
-        cfg.general.me_writer_pick_mode,
-        cfg.general.me_writer_pick_sample_size,
-        cfg.general.me_single_endpoint_shadow_writers,
-        cfg.general.me_single_endpoint_outage_mode_enabled,
-        cfg.general.me_single_endpoint_outage_disable_quarantine,
-        cfg.general.me_single_endpoint_outage_backoff_min_ms,
-        cfg.general.me_single_endpoint_outage_backoff_max_ms,
-        cfg.general.me_single_endpoint_shadow_rotate_every_secs,
-        cfg.general.me_floor_mode,
-        cfg.general.me_adaptive_floor_idle_secs,
-        cfg.general.me_adaptive_floor_min_writers_single_endpoint,
-        cfg.general.me_adaptive_floor_min_writers_multi_endpoint,
-        cfg.general.me_adaptive_floor_recover_grace_secs,
-        cfg.general.me_adaptive_floor_writers_per_core_total,
-        cfg.general.me_adaptive_floor_cpu_cores_override,
-        cfg.general
-            .me_adaptive_floor_max_extra_writers_single_per_core,
-        cfg.general
-            .me_adaptive_floor_max_extra_writers_multi_per_core,
-        cfg.general.me_adaptive_floor_max_active_writers_per_core,
-        cfg.general.me_adaptive_floor_max_warm_writers_per_core,
-        cfg.general.me_adaptive_floor_max_active_writers_global,
-        cfg.general.me_adaptive_floor_max_warm_writers_global,
-        cfg.general.me_health_interval_ms_unhealthy,
-        cfg.general.me_health_interval_ms_healthy,
-        cfg.general.me_warn_rate_limit_ms,
-    );
 
     let required_cfg_snapshots = cfg.general.me_config_stable_snapshots.max(1);
     let required_secret_snapshots = cfg.general.proxy_secret_stable_snapshots.max(1);

src/transport/middle_proxy/handshake.rs

@@ -161,7 +161,7 @@ impl MePool {
         } else {
             let connect_fut = async {
                 if addr.is_ipv6()
-                    && let Some(v6) = self.detected_ipv6
+                    && let Some(v6) = self.nat_runtime.detected_ipv6
                 {
                     match TcpSocket::new_v6() {
                         Ok(sock) => {
@@ -305,7 +305,7 @@ impl MePool {
                 }
                 MeSocksKdfPolicy::Compat => {
                     self.stats.increment_me_socks_kdf_compat_fallback();
-                    if self.nat_probe {
+                    if self.nat_runtime.nat_probe {
                         let bind_ip = Self::direct_bind_ip_for_stun(family, upstream_egress);
                         self.maybe_reflect_public_addr(family, bind_ip).await
                     } else {
@@ -313,7 +313,7 @@ impl MePool {
                     }
                 }
             }
-        } else if self.nat_probe {
+        } else if self.nat_runtime.nat_probe {
             let bind_ip = Self::direct_bind_ip_for_stun(family, upstream_egress);
             self.maybe_reflect_public_addr(family, bind_ip).await
         } else {
@@ -343,7 +343,10 @@ impl MePool {
             .unwrap_or_default()
             .as_secs() as u32;
 
-        let secret_atomic_snapshot = self.secret_atomic_snapshot.load(Ordering::Relaxed);
+        let secret_atomic_snapshot = self
+            .writer_selection_policy
+            .secret_atomic_snapshot
+            .load(Ordering::Relaxed);
         let (ks, secret) = if secret_atomic_snapshot {
             let snapshot = self.secret_snapshot().await;
             (snapshot.key_selector, snapshot.secret)

src/transport/middle_proxy/health.rs

@@ -7,6 +7,8 @@ use std::sync::Arc;
 use std::time::{Duration, Instant};
 
 use rand::RngExt;
+use tokio::sync::Semaphore;
+use tokio::task::JoinSet;
 use tracing::{debug, info, warn};
 
 use crate::config::MeFloorMode;
@@ -14,6 +16,7 @@ use crate::crypto::SecureRandom;
 use crate::network::IpFamily;
 
 use super::MePool;
+use super::pool::MeFamilyRuntimeState;
 
 const JITTER_FRAC_NUM: u64 = 2; // jitter up to 50% of backoff
 #[allow(dead_code)]
@@ -27,6 +30,9 @@ const HEALTH_RECONNECT_BUDGET_PER_CORE: usize = 2;
 const HEALTH_RECONNECT_BUDGET_PER_DC: usize = 1;
 const HEALTH_RECONNECT_BUDGET_MIN: usize = 4;
 const HEALTH_RECONNECT_BUDGET_MAX: usize = 128;
+const FAMILY_SUPPRESS_FAIL_STREAK_THRESHOLD: u32 = 5;
+const FAMILY_SUPPRESS_DURATION_SECS: u64 = 60;
+const FAMILY_RECOVER_SUCCESS_STREAK_TARGET: u32 = 2;
 const HEALTH_DRAIN_CLOSE_BUDGET_PER_CORE: usize = 16;
 const HEALTH_DRAIN_CLOSE_BUDGET_MIN: usize = 16;
 const HEALTH_DRAIN_CLOSE_BUDGET_MAX: usize = 256;
@@ -56,6 +62,17 @@ struct FamilyFloorPlan {
     target_writers_total: usize,
 }
 
+#[derive(Debug)]
+struct FamilyReconnectOutcome {
+    key: (i32, IpFamily),
+    dc: i32,
+    family: IpFamily,
+    alive: usize,
+    required: usize,
+    endpoint_count: usize,
+    restored: usize,
+}
+
 pub async fn me_health_monitor(pool: Arc<MePool>, rng: Arc<SecureRandom>, _min_connections: usize) {
     let mut backoff: HashMap<(i32, IpFamily), u64> = HashMap::new();
     let mut next_attempt: HashMap<(i32, IpFamily), Instant> = HashMap::new();
@@ -78,6 +95,7 @@ pub async fn me_health_monitor(pool: Arc<MePool>, rng: Arc<SecureRandom>, _min_c
         };
         tokio::time::sleep(interval).await;
         pool.prune_closed_writers().await;
+        pool.sweep_endpoint_quarantine().await;
         reap_draining_writers(&pool, &mut drain_warn_next_allowed).await;
         let v4_degraded = check_family(
             IpFamily::V4,
@@ -113,6 +131,8 @@ pub async fn me_health_monitor(pool: Arc<MePool>, rng: Arc<SecureRandom>, _min_c
             &mut floor_warn_next_allowed,
         )
         .await;
+        update_family_runtime_state(&pool, IpFamily::V4, v4_degraded);
+        update_family_runtime_state(&pool, IpFamily::V6, v6_degraded);
         degraded_interval = v4_degraded || v6_degraded;
     }
 }
@@ -135,9 +155,11 @@ pub(super) async fn reap_draining_writers(
     let now_epoch_secs = MePool::now_epoch_secs();
     let now = Instant::now();
     let drain_ttl_secs = pool
+        .drain_runtime
         .me_pool_drain_ttl_secs
         .load(std::sync::atomic::Ordering::Relaxed);
     let drain_threshold = pool
+        .drain_runtime
         .me_pool_drain_threshold
         .load(std::sync::atomic::Ordering::Relaxed);
     let activity = pool.registry.writer_activity_snapshot().await;
@@ -221,7 +243,10 @@ pub(super) async fn reap_draining_writers(
                 endpoint = %writer.addr,
                 generation = writer.generation,
                 drain_ttl_secs,
-                force_close_secs = pool.me_pool_force_close_secs.load(std::sync::atomic::Ordering::Relaxed),
+                force_close_secs = pool
+                    .drain_runtime
+                    .me_pool_force_close_secs
+                    .load(std::sync::atomic::Ordering::Relaxed),
                 allow_drain_fallback = writer.allow_drain_fallback,
                 "ME draining writer remains non-empty past drain TTL"
             );
@@ -365,7 +390,8 @@ async fn check_family(
         endpoints.sort_unstable();
         endpoints.dedup();
     }
-    let mut reconnect_budget = health_reconnect_budget(pool, dc_endpoints.len());
+    let reconnect_budget = health_reconnect_budget(pool, dc_endpoints.len());
+    let reconnect_sem = Arc::new(Semaphore::new(reconnect_budget));
 
     if pool.floor_mode() == MeFloorMode::Static {
         adaptive_idle_since.clear();
@@ -422,6 +448,10 @@ async fn check_family(
         floor_plan.active_writers_current,
         floor_plan.warm_writers_current,
     );
+    let live_writer_ids_by_addr = Arc::new(live_writer_ids_by_addr);
+    let writer_idle_since = Arc::new(writer_idle_since);
+    let bound_clients_by_writer = Arc::new(bound_clients_by_writer);
+    let mut reconnect_set = JoinSet::<FamilyReconnectOutcome>::new();
 
     for (dc, endpoints) in dc_endpoints {
         if endpoints.is_empty() {
@@ -461,7 +491,7 @@ async fn check_family(
                 required,
                 outage_backoff,
                 outage_next_attempt,
-                &mut reconnect_budget,
+                &reconnect_sem,
             )
             .await;
             continue;
@@ -495,9 +525,9 @@ async fn check_family(
                 &endpoints,
                 alive,
                 required,
-                &live_writer_ids_by_addr,
-                &writer_idle_since,
-                &bound_clients_by_writer,
+                live_writer_ids_by_addr.as_ref(),
+                writer_idle_since.as_ref(),
+                bound_clients_by_writer.as_ref(),
                 idle_refresh_next_attempt,
             )
             .await;
@@ -510,8 +540,8 @@ async fn check_family(
                 &endpoints,
                 alive,
                 required,
-                &live_writer_ids_by_addr,
-                &bound_clients_by_writer,
+                live_writer_ids_by_addr.as_ref(),
+                bound_clients_by_writer.as_ref(),
                 shadow_rotate_deadline,
             )
             .await;
@@ -521,8 +551,8 @@ async fn check_family(
         family_degraded = true;
 
         let now = Instant::now();
-        if reconnect_budget == 0 {
-            let base_ms = pool.me_reconnect_backoff_base.as_millis() as u64;
+        if reconnect_sem.available_permits() == 0 {
+            let base_ms = pool.reconnect_runtime.me_reconnect_backoff_base.as_millis() as u64;
             let next_ms = (*backoff.get(&key).unwrap_or(&base_ms)).max(base_ms);
             let jitter = next_ms / JITTER_FRAC_NUM;
             let wait = Duration::from_millis(next_ms)
@@ -545,7 +575,10 @@ async fn check_family(
             continue;
         }
 
-        let max_concurrent = pool.me_reconnect_max_concurrent_per_dc.max(1) as usize;
+        let max_concurrent = pool
+            .reconnect_runtime
+            .me_reconnect_max_concurrent_per_dc
+            .max(1) as usize;
         if *inflight.get(&key).unwrap_or(&0) >= max_concurrent {
             continue;
         }
@@ -564,117 +597,165 @@ async fn check_family(
             continue;
         }
         *inflight.entry(key).or_insert(0) += 1;
-
-        let mut restored = 0usize;
-        for _ in 0..missing {
-            if reconnect_budget == 0 {
-                break;
-            }
-            reconnect_budget = reconnect_budget.saturating_sub(1);
-            if pool.active_contour_writer_count_total().await
-                >= floor_plan.active_cap_effective_total
-            {
-                let swapped = maybe_swap_idle_writer_for_cap(
-                    pool,
-                    rng,
-                    dc,
-                    family,
-                    &endpoints,
-                    &live_writer_ids_by_addr,
-                    &writer_idle_since,
-                    &bound_clients_by_writer,
+        let pool_for_reconnect = pool.clone();
+        let rng_for_reconnect = rng.clone();
+        let reconnect_sem_for_dc = reconnect_sem.clone();
+        let endpoints_for_dc = endpoints.clone();
+        let live_writer_ids_by_addr_for_dc = live_writer_ids_by_addr.clone();
+        let writer_idle_since_for_dc = writer_idle_since.clone();
+        let bound_clients_by_writer_for_dc = bound_clients_by_writer.clone();
+        let active_cap_effective_total = floor_plan.active_cap_effective_total;
+        reconnect_set.spawn(async move {
+            let mut restored = 0usize;
+            for _ in 0..missing {
+                let Ok(reconnect_permit) = reconnect_sem_for_dc.clone().try_acquire_owned() else {
+                    break;
+                };
+                if pool_for_reconnect.active_contour_writer_count_total().await
+                    >= active_cap_effective_total
+                {
+                    let swapped = maybe_swap_idle_writer_for_cap(
+                        &pool_for_reconnect,
+                        &rng_for_reconnect,
+                        dc,
+                        family,
+                        &endpoints_for_dc,
+                        live_writer_ids_by_addr_for_dc.as_ref(),
+                        writer_idle_since_for_dc.as_ref(),
+                        bound_clients_by_writer_for_dc.as_ref(),
+                    )
+                    .await;
+                    if swapped {
+                        pool_for_reconnect
+                            .stats
+                            .increment_me_floor_swap_idle_total();
+                        restored += 1;
+                        continue;
+                    }
+                    pool_for_reconnect
+                        .stats
+                        .increment_me_floor_cap_block_total();
+                    pool_for_reconnect
+                        .stats
+                        .increment_me_floor_swap_idle_failed_total();
+                    debug!(
+                        dc = %dc,
+                        ?family,
+                        alive,
+                        required,
+                        active_cap_effective_total,
+                        "Adaptive floor cap reached, reconnect attempt blocked"
+                    );
+                    break;
+                }
+                let res = tokio::time::timeout(
+                    pool_for_reconnect.reconnect_runtime.me_one_timeout,
+                    pool_for_reconnect.connect_endpoints_round_robin(
+                        dc,
+                        &endpoints_for_dc,
+                        rng_for_reconnect.as_ref(),
+                    ),
                 )
                 .await;
-                if swapped {
-                    pool.stats.increment_me_floor_swap_idle_total();
-                    restored += 1;
-                    continue;
+                match res {
+                    Ok(true) => {
+                        restored += 1;
+                        pool_for_reconnect.stats.increment_me_reconnect_success();
+                    }
+                    Ok(false) => {
+                        pool_for_reconnect.stats.increment_me_reconnect_attempt();
+                        debug!(dc = %dc, ?family, "ME round-robin reconnect failed")
+                    }
+                    Err(_) => {
+                        pool_for_reconnect.stats.increment_me_reconnect_attempt();
+                        debug!(dc = %dc, ?family, "ME reconnect timed out");
+                    }
                 }
-                pool.stats.increment_me_floor_cap_block_total();
-                pool.stats.increment_me_floor_swap_idle_failed_total();
-                debug!(
-                    dc = %dc,
-                    ?family,
-                    alive,
-                    required,
-                    active_cap_effective_total = floor_plan.active_cap_effective_total,
-                    "Adaptive floor cap reached, reconnect attempt blocked"
-                );
-                break;
+                drop(reconnect_permit);
             }
-            let res = tokio::time::timeout(
-                pool.me_one_timeout,
-                pool.connect_endpoints_round_robin(dc, &endpoints, rng.as_ref()),
-            )
-            .await;
-            match res {
-                Ok(true) => {
-                    restored += 1;
-                    pool.stats.increment_me_reconnect_success();
-                }
-                Ok(false) => {
-                    pool.stats.increment_me_reconnect_attempt();
-                    debug!(dc = %dc, ?family, "ME round-robin reconnect failed")
-                }
-                Err(_) => {
-                    pool.stats.increment_me_reconnect_attempt();
-                    debug!(dc = %dc, ?family, "ME reconnect timed out");
-                }
-            }
-        }
 
-        let now_alive = alive + restored;
-        if now_alive >= required {
-            info!(
-                dc = %dc,
-                ?family,
-                alive = now_alive,
+            FamilyReconnectOutcome {
+                key,
+                dc,
+                family,
+                alive,
                 required,
-                endpoint_count = endpoints.len(),
+                endpoint_count: endpoints_for_dc.len(),
+                restored,
+            }
+        });
+    }
+
+    while let Some(joined) = reconnect_set.join_next().await {
+        let outcome = match joined {
+            Ok(outcome) => outcome,
+            Err(join_error) => {
+                debug!(error = %join_error, "Health reconnect task failed");
+                continue;
+            }
+        };
+        let now = Instant::now();
+        let now_alive = outcome.alive + outcome.restored;
+        if now_alive >= outcome.required {
+            info!(
+                dc = %outcome.dc,
+                family = ?outcome.family,
+                alive = now_alive,
+                required = outcome.required,
+                endpoint_count = outcome.endpoint_count,
                 "ME writer floor restored for DC"
             );
-            backoff.insert(key, pool.me_reconnect_backoff_base.as_millis() as u64);
-            let jitter = pool.me_reconnect_backoff_base.as_millis() as u64 / JITTER_FRAC_NUM;
-            let wait = pool.me_reconnect_backoff_base
+            backoff.insert(
+                outcome.key,
+                pool.reconnect_runtime.me_reconnect_backoff_base.as_millis() as u64,
+            );
+            let jitter = pool.reconnect_runtime.me_reconnect_backoff_base.as_millis() as u64
+                / JITTER_FRAC_NUM;
+            let wait = pool.reconnect_runtime.me_reconnect_backoff_base
                 + Duration::from_millis(rand::rng().random_range(0..=jitter.max(1)));
-            next_attempt.insert(key, now + wait);
+            next_attempt.insert(outcome.key, now + wait);
         } else {
             let curr = *backoff
-                .get(&key)
-                .unwrap_or(&(pool.me_reconnect_backoff_base.as_millis() as u64));
-            let next_ms =
-                (curr.saturating_mul(2)).min(pool.me_reconnect_backoff_cap.as_millis() as u64);
-            backoff.insert(key, next_ms);
+                .get(&outcome.key)
+                .unwrap_or(&(pool.reconnect_runtime.me_reconnect_backoff_base.as_millis() as u64));
+            let next_ms = (curr.saturating_mul(2))
+                .min(pool.reconnect_runtime.me_reconnect_backoff_cap.as_millis() as u64);
+            backoff.insert(outcome.key, next_ms);
             let jitter = next_ms / JITTER_FRAC_NUM;
             let wait = Duration::from_millis(next_ms)
                 + Duration::from_millis(rand::rng().random_range(0..=jitter.max(1)));
-            next_attempt.insert(key, now + wait);
+            next_attempt.insert(outcome.key, now + wait);
             if pool.is_runtime_ready() {
                 let warn_cooldown = pool.warn_rate_limit_duration();
-                if should_emit_rate_limited_warn(floor_warn_next_allowed, key, now, warn_cooldown) {
+                if should_emit_rate_limited_warn(
+                    floor_warn_next_allowed,
+                    outcome.key,
+                    now,
+                    warn_cooldown,
+                ) {
                     warn!(
-                        dc = %dc,
-                        ?family,
+                        dc = %outcome.dc,
+                        family = ?outcome.family,
                         alive = now_alive,
-                        required,
-                        endpoint_count = endpoints.len(),
+                        required = outcome.required,
+                        endpoint_count = outcome.endpoint_count,
                         backoff_ms = next_ms,
                         "DC writer floor is below required level, scheduled reconnect"
                     );
                 }
             } else {
                 info!(
-                    dc = %dc,
-                    ?family,
+                    dc = %outcome.dc,
+                    family = ?outcome.family,
                     alive = now_alive,
-                    required,
-                    endpoint_count = endpoints.len(),
+                    required = outcome.required,
+                    endpoint_count = outcome.endpoint_count,
                     backoff_ms = next_ms,
                     "DC writer floor is below required level during startup, scheduled reconnect"
                 );
             }
         }
-        if let Some(v) = inflight.get_mut(&key) {
+        if let Some(v) = inflight.get_mut(&outcome.key) {
             *v = v.saturating_sub(1);
         }
     }
@@ -691,6 +772,68 @@ fn health_reconnect_budget(pool: &Arc<MePool>, dc_groups: usize) -> usize {
         .clamp(HEALTH_RECONNECT_BUDGET_MIN, HEALTH_RECONNECT_BUDGET_MAX)
 }
 
+fn update_family_runtime_state(pool: &Arc<MePool>, family: IpFamily, degraded: bool) {
+    let now_epoch_secs = MePool::now_epoch_secs();
+    let previous_state = pool.family_runtime_state(family);
+    let mut state_since_epoch_secs = pool.family_runtime_state_since_epoch_secs(family);
+    let previous_suppressed_until_epoch_secs = pool.family_suppressed_until_epoch_secs(family);
+    let previous_fail_streak = pool.family_fail_streak(family);
+    let previous_recover_success_streak = pool.family_recover_success_streak(family);
+
+    let (next_state, suppressed_until_epoch_secs, fail_streak, recover_success_streak) =
+        if previous_suppressed_until_epoch_secs > now_epoch_secs {
+            let fail_streak = if degraded {
+                previous_fail_streak.saturating_add(1)
+            } else {
+                previous_fail_streak
+            };
+            (
+                MeFamilyRuntimeState::Suppressed,
+                previous_suppressed_until_epoch_secs,
+                fail_streak,
+                0,
+            )
+        } else if degraded {
+            let fail_streak = previous_fail_streak.saturating_add(1);
+            if fail_streak >= FAMILY_SUPPRESS_FAIL_STREAK_THRESHOLD {
+                (
+                    MeFamilyRuntimeState::Suppressed,
+                    now_epoch_secs.saturating_add(FAMILY_SUPPRESS_DURATION_SECS),
+                    fail_streak,
+                    0,
+                )
+            } else {
+                (MeFamilyRuntimeState::Degraded, 0, fail_streak, 0)
+            }
+        } else if matches!(previous_state, MeFamilyRuntimeState::Healthy) {
+            (MeFamilyRuntimeState::Healthy, 0, 0, 0)
+        } else {
+            let recover_success_streak = previous_recover_success_streak.saturating_add(1);
+            if recover_success_streak >= FAMILY_RECOVER_SUCCESS_STREAK_TARGET {
+                (MeFamilyRuntimeState::Healthy, 0, 0, 0)
+            } else {
+                (
+                    MeFamilyRuntimeState::Recovering,
+                    0,
+                    0,
+                    recover_success_streak,
+                )
+            }
+        };
+
+    if next_state != previous_state || state_since_epoch_secs == 0 {
+        state_since_epoch_secs = now_epoch_secs;
+    }
+    pool.set_family_runtime_state(
+        family,
+        next_state,
+        state_since_epoch_secs,
+        suppressed_until_epoch_secs,
+        fail_streak,
+        recover_success_streak,
+    );
+}
+
 fn should_emit_rate_limited_warn(
     next_allowed: &mut HashMap<(i32, IpFamily), Instant>,
     key: (i32, IpFamily),
@@ -715,6 +858,7 @@ fn adaptive_floor_class_min(
 ) -> usize {
     if endpoint_count <= 1 {
         let min_single = (pool
+            .floor_runtime
             .me_adaptive_floor_min_writers_single_endpoint
             .load(std::sync::atomic::Ordering::Relaxed) as usize)
             .max(1);
@@ -971,7 +1115,7 @@ async fn maybe_swap_idle_writer_for_cap(
     };
 
     let connected = match tokio::time::timeout(
-        pool.me_one_timeout,
+        pool.reconnect_runtime.me_one_timeout,
         pool.connect_one_for_dc(endpoint, dc, rng.as_ref()),
     )
     .await
@@ -1077,7 +1221,7 @@ async fn maybe_refresh_idle_writer_for_dc(
     };
 
     let rotate_ok = match tokio::time::timeout(
-        pool.me_one_timeout,
+        pool.reconnect_runtime.me_one_timeout,
         pool.connect_one_for_dc(endpoint, dc, rng.as_ref()),
     )
     .await
@@ -1188,7 +1332,7 @@ async fn recover_single_endpoint_outage(
     required: usize,
     outage_backoff: &mut HashMap<(i32, IpFamily), u64>,
     outage_next_attempt: &mut HashMap<(i32, IpFamily), Instant>,
-    reconnect_budget: &mut usize,
+    reconnect_sem: &Arc<Semaphore>,
 ) {
     let now = Instant::now();
     if let Some(ts) = outage_next_attempt.get(&key)
@@ -1198,7 +1342,7 @@ async fn recover_single_endpoint_outage(
     }
 
     let (min_backoff_ms, max_backoff_ms) = pool.single_endpoint_outage_backoff_bounds_ms();
-    if *reconnect_budget == 0 {
+    if reconnect_sem.available_permits() == 0 {
         outage_next_attempt.insert(key, now + Duration::from_millis(min_backoff_ms.max(250)));
         debug!(
             dc = %key.0,
@@ -1209,7 +1353,17 @@ async fn recover_single_endpoint_outage(
         );
         return;
     }
-    *reconnect_budget = (*reconnect_budget).saturating_sub(1);
+    let Ok(_reconnect_permit) = reconnect_sem.clone().try_acquire_owned() else {
+        outage_next_attempt.insert(key, now + Duration::from_millis(min_backoff_ms.max(250)));
+        debug!(
+            dc = %key.0,
+            family = ?key.1,
+            %endpoint,
+            required,
+            "Single-endpoint outage reconnect deferred by semaphore saturation"
+        );
+        return;
+    };
     pool.stats
         .increment_me_single_endpoint_outage_reconnect_attempt_total();
 
@@ -1218,7 +1372,7 @@ async fn recover_single_endpoint_outage(
         pool.stats
             .increment_me_single_endpoint_quarantine_bypass_total();
         match tokio::time::timeout(
-            pool.me_one_timeout,
+            pool.reconnect_runtime.me_one_timeout,
             pool.connect_one_for_dc(endpoint, key.0, rng.as_ref()),
         )
         .await
@@ -1247,7 +1401,7 @@ async fn recover_single_endpoint_outage(
     } else {
         let one_endpoint = [endpoint];
         match tokio::time::timeout(
-            pool.me_one_timeout,
+            pool.reconnect_runtime.me_one_timeout,
             pool.connect_endpoints_round_robin(key.0, &one_endpoint, rng.as_ref()),
         )
         .await
@@ -1372,7 +1526,7 @@ async fn maybe_rotate_single_endpoint_shadow(
     };
 
     let rotate_ok = match tokio::time::timeout(
-        pool.me_one_timeout,
+        pool.reconnect_runtime.me_one_timeout,
         pool.connect_one_for_dc(endpoint, dc, rng.as_ref()),
     )
     .await
@@ -1687,6 +1841,8 @@ mod tests {
             general.me_warn_rate_limit_ms,
             MeRouteNoWriterMode::default(),
             general.me_route_no_writer_wait_ms,
+            general.me_route_hybrid_max_wait_ms,
+            general.me_route_blocking_send_timeout_ms,
             general.me_route_inline_recovery_attempts,
             general.me_route_inline_recovery_wait_ms,
         )

src/transport/middle_proxy/pool_config.rs

@@ -72,7 +72,7 @@ impl MePool {
         }
         if changed {
             self.rebuild_endpoint_dc_map().await;
-            self.writer_available.notify_waiters();
+            self.notify_writer_epoch();
         }
         if changed {
             SnapshotApplyOutcome::AppliedChanged
@@ -112,7 +112,7 @@ impl MePool {
 
     pub async fn reconnect_all(self: &Arc<Self>) {
         let ws = self.writers.read().await.clone();
-        for w in ws {
+        for w in ws.iter() {
             if let Ok(()) = self
                 .connect_one_for_dc(w.addr, w.writer_dc, self.rng.as_ref())
                 .await

src/transport/middle_proxy/pool_init.rs

@@ -14,7 +14,10 @@ use super::pool::MePool;
 impl MePool {
     pub async fn init(self: &Arc<Self>, pool_size: usize, rng: &Arc<SecureRandom>) -> Result<()> {
         let family_order = self.family_order();
-        let connect_concurrency = self.me_reconnect_max_concurrent_per_dc.max(1) as usize;
+        let connect_concurrency = self
+            .reconnect_runtime
+            .me_reconnect_max_concurrent_per_dc
+            .max(1) as usize;
         let ks = self.key_selector().await;
         info!(
             me_servers = self.proxy_map_v4.read().await.len(),
@@ -250,10 +253,12 @@ impl MePool {
                 return false;
             }
 
-            if self.me_warmup_stagger_enabled {
-                let jitter =
-                    rand::rng().random_range(0..=self.me_warmup_step_jitter.as_millis() as u64);
-                let delay_ms = self.me_warmup_step_delay.as_millis() as u64 + jitter;
+            if self.reconnect_runtime.me_warmup_stagger_enabled {
+                let jitter = rand::rng().random_range(
+                    0..=self.reconnect_runtime.me_warmup_step_jitter.as_millis() as u64,
+                );
+                let delay_ms =
+                    self.reconnect_runtime.me_warmup_step_delay.as_millis() as u64 + jitter;
                 tokio::time::sleep(std::time::Duration::from_millis(delay_ms)).await;
             }
         }

src/transport/middle_proxy/pool_nat.rs

@@ -42,10 +42,10 @@ pub async fn detect_public_ip() -> Option<IpAddr> {
 
 impl MePool {
     fn configured_stun_servers(&self) -> Vec<String> {
-        if !self.nat_stun_servers.is_empty() {
-            return self.nat_stun_servers.clone();
+        if !self.nat_runtime.nat_stun_servers.is_empty() {
+            return self.nat_runtime.nat_stun_servers.clone();
         }
-        if let Some(s) = &self.nat_stun
+        if let Some(s) = &self.nat_runtime.nat_stun
             && !s.trim().is_empty()
         {
             return vec![s.clone()];
@@ -64,7 +64,7 @@ impl MePool {
         let mut next_idx = 0usize;
         let mut live_servers = Vec::new();
         let mut best_by_ip: HashMap<IpAddr, (usize, std::net::SocketAddr)> = HashMap::new();
-        let concurrency = self.nat_probe_concurrency.max(1);
+        let concurrency = self.nat_runtime.nat_probe_concurrency.max(1);
 
         while next_idx < servers.len() || !join_set.is_empty() {
             while next_idx < servers.len() && join_set.len() < concurrency {
@@ -137,9 +137,13 @@ impl MePool {
     }
 
     pub(super) fn translate_ip_for_nat(&self, ip: IpAddr) -> IpAddr {
-        let nat_ip = self
-            .nat_ip_cfg
-            .or_else(|| self.nat_ip_detected.try_read().ok().and_then(|g| *g));
+        let nat_ip = self.nat_runtime.nat_ip_cfg.or_else(|| {
+            self.nat_runtime
+                .nat_ip_detected
+                .try_read()
+                .ok()
+                .and_then(|g| *g)
+        });
 
         let Some(nat_ip) = nat_ip else {
             return ip;
@@ -163,7 +167,7 @@ impl MePool {
         addr: std::net::SocketAddr,
         reflected: Option<std::net::SocketAddr>,
     ) -> std::net::SocketAddr {
-        let ip = if let Some(nat_ip) = self.nat_ip_cfg {
+        let ip = if let Some(nat_ip) = self.nat_runtime.nat_ip_cfg {
             match (addr.ip(), nat_ip) {
                 (IpAddr::V4(_), IpAddr::V4(dst)) => IpAddr::V4(dst),
                 (IpAddr::V6(_), IpAddr::V6(dst)) => IpAddr::V6(dst),
@@ -185,22 +189,22 @@ impl MePool {
     }
 
     pub(super) async fn maybe_detect_nat_ip(&self, local_ip: IpAddr) -> Option<IpAddr> {
-        if self.nat_ip_cfg.is_some() {
-            return self.nat_ip_cfg;
+        if self.nat_runtime.nat_ip_cfg.is_some() {
+            return self.nat_runtime.nat_ip_cfg;
         }
 
         if !(is_bogon(local_ip) || local_ip.is_loopback() || local_ip.is_unspecified()) {
             return None;
         }
 
-        if let Some(ip) = *self.nat_ip_detected.read().await {
+        if let Some(ip) = *self.nat_runtime.nat_ip_detected.read().await {
             return Some(ip);
         }
 
         match fetch_public_ipv4_with_retry().await {
             Ok(Some(ip)) => {
                 {
-                    let mut guard = self.nat_ip_detected.write().await;
+                    let mut guard = self.nat_runtime.nat_ip_detected.write().await;
                     *guard = Some(IpAddr::V4(ip));
                 }
                 info!(public_ip = %ip, "Auto-detected public IP for NAT translation");
@@ -231,10 +235,10 @@ impl MePool {
         }
         // Backoff window
         if use_shared_cache
-            && let Some(until) = *self.stun_backoff_until.read().await
+            && let Some(until) = *self.nat_runtime.stun_backoff_until.read().await
             && Instant::now() < until
         {
-            if let Ok(cache) = self.nat_reflection_cache.try_lock() {
+            if let Ok(cache) = self.nat_runtime.nat_reflection_cache.try_lock() {
                 let slot = match family {
                     IpFamily::V4 => cache.v4,
                     IpFamily::V6 => cache.v6,
@@ -244,7 +248,8 @@ impl MePool {
             return None;
         }
 
-        if use_shared_cache && let Ok(mut cache) = self.nat_reflection_cache.try_lock() {
+        if use_shared_cache && let Ok(mut cache) = self.nat_runtime.nat_reflection_cache.try_lock()
+        {
             let slot = match family {
                 IpFamily::V4 => &mut cache.v4,
                 IpFamily::V6 => &mut cache.v6,
@@ -258,18 +263,18 @@ impl MePool {
 
         let _singleflight_guard = if use_shared_cache {
             Some(match family {
-                IpFamily::V4 => self.nat_reflection_singleflight_v4.lock().await,
-                IpFamily::V6 => self.nat_reflection_singleflight_v6.lock().await,
+                IpFamily::V4 => self.nat_runtime.nat_reflection_singleflight_v4.lock().await,
+                IpFamily::V6 => self.nat_runtime.nat_reflection_singleflight_v6.lock().await,
             })
         } else {
             None
         };
 
         if use_shared_cache
-            && let Some(until) = *self.stun_backoff_until.read().await
+            && let Some(until) = *self.nat_runtime.stun_backoff_until.read().await
             && Instant::now() < until
         {
-            if let Ok(cache) = self.nat_reflection_cache.try_lock() {
+            if let Ok(cache) = self.nat_runtime.nat_reflection_cache.try_lock() {
                 let slot = match family {
                     IpFamily::V4 => cache.v4,
                     IpFamily::V6 => cache.v6,
@@ -279,7 +284,8 @@ impl MePool {
             return None;
         }
 
-        if use_shared_cache && let Ok(mut cache) = self.nat_reflection_cache.try_lock() {
+        if use_shared_cache && let Ok(mut cache) = self.nat_runtime.nat_reflection_cache.try_lock()
+        {
             let slot = match family {
                 IpFamily::V4 => &mut cache.v4,
                 IpFamily::V6 => &mut cache.v6,
@@ -292,13 +298,14 @@ impl MePool {
         }
 
         let attempt = if use_shared_cache {
-            self.nat_probe_attempts
+            self.nat_runtime
+                .nat_probe_attempts
                 .fetch_add(1, std::sync::atomic::Ordering::Relaxed)
         } else {
             0
         };
         let configured_servers = self.configured_stun_servers();
-        let live_snapshot = self.nat_stun_live_servers.read().await.clone();
+        let live_snapshot = self.nat_runtime.nat_stun_live_servers.read().await.clone();
         let primary_servers = if live_snapshot.is_empty() {
             configured_servers.clone()
         } else {
@@ -322,14 +329,15 @@ impl MePool {
 
         let live_server_count = live_servers.len();
         if !live_servers.is_empty() {
-            *self.nat_stun_live_servers.write().await = live_servers;
+            *self.nat_runtime.nat_stun_live_servers.write().await = live_servers;
         } else {
-            self.nat_stun_live_servers.write().await.clear();
+            self.nat_runtime.nat_stun_live_servers.write().await.clear();
         }
 
         if let Some(reflected_addr) = selected_reflected {
             if use_shared_cache {
-                self.nat_probe_attempts
+                self.nat_runtime
+                    .nat_probe_attempts
                     .store(0, std::sync::atomic::Ordering::Relaxed);
             }
             info!(
@@ -338,7 +346,9 @@ impl MePool {
                 "STUN-Quorum reached, IP: {}",
                 reflected_addr.ip()
             );
-            if use_shared_cache && let Ok(mut cache) = self.nat_reflection_cache.try_lock() {
+            if use_shared_cache
+                && let Ok(mut cache) = self.nat_runtime.nat_reflection_cache.try_lock()
+            {
                 let slot = match family {
                     IpFamily::V4 => &mut cache.v4,
                     IpFamily::V6 => &mut cache.v6,
@@ -350,7 +360,7 @@ impl MePool {
 
         if use_shared_cache {
             let backoff = Duration::from_secs(60 * 2u64.pow((attempt as u32).min(6)));
-            *self.stun_backoff_until.write().await = Some(Instant::now() + backoff);
+            *self.nat_runtime.stun_backoff_until.write().await = Some(Instant::now() + backoff);
         }
         None
     }

src/transport/middle_proxy/pool_refill.rs

@@ -13,13 +13,40 @@ use super::pool::{MePool, RefillDcKey, RefillEndpointKey, WriterContour};
 
 const ME_FLAP_UPTIME_THRESHOLD_SECS: u64 = 20;
 const ME_FLAP_QUARANTINE_SECS: u64 = 25;
+const ME_FLAP_MIN_UPTIME_MILLIS: u64 = 500;
+const ME_REFILL_TOTAL_ATTEMPT_CAP: u32 = 20;
 
 impl MePool {
+    pub(super) async fn sweep_endpoint_quarantine(&self) {
+        let configured = self
+            .endpoint_dc_map
+            .read()
+            .await
+            .keys()
+            .copied()
+            .collect::<HashSet<SocketAddr>>();
+        let now = Instant::now();
+        let mut guard = self.endpoint_quarantine.lock().await;
+        guard.retain(|addr, expiry| *expiry > now && configured.contains(addr));
+    }
+
     pub(super) async fn maybe_quarantine_flapping_endpoint(
         &self,
         addr: SocketAddr,
         uptime: Duration,
+        reason: &'static str,
     ) {
+        if uptime < Duration::from_millis(ME_FLAP_MIN_UPTIME_MILLIS) {
+            debug!(
+                %addr,
+                reason,
+                uptime_ms = uptime.as_millis(),
+                min_uptime_ms = ME_FLAP_MIN_UPTIME_MILLIS,
+                "Skipping flap quarantine for ultra-short writer lifetime"
+            );
+            return;
+        }
+
         if uptime > Duration::from_secs(ME_FLAP_UPTIME_THRESHOLD_SECS) {
             return;
         }
@@ -31,6 +58,7 @@ impl MePool {
         self.stats.increment_me_endpoint_quarantine_total();
         warn!(
             %addr,
+            reason,
             uptime_ms = uptime.as_millis(),
             quarantine_secs = ME_FLAP_QUARANTINE_SECS,
             "ME endpoint temporarily quarantined due to rapid writer flap"
@@ -205,11 +233,16 @@ impl MePool {
     }
 
     async fn refill_writer_after_loss(self: &Arc<Self>, addr: SocketAddr, writer_dc: i32) -> bool {
-        let fast_retries = self.me_reconnect_fast_retry_count.max(1);
+        let fast_retries = self.reconnect_runtime.me_reconnect_fast_retry_count.max(1);
+        let mut total_attempts = 0u32;
         let same_endpoint_quarantined = self.is_endpoint_quarantined(addr).await;
 
         if !same_endpoint_quarantined {
             for attempt in 0..fast_retries {
+                if total_attempts >= ME_REFILL_TOTAL_ATTEMPT_CAP {
+                    break;
+                }
+                total_attempts = total_attempts.saturating_add(1);
                 self.stats.increment_me_reconnect_attempt();
                 match self
                     .connect_one_for_dc(addr, writer_dc, self.rng.as_ref())
@@ -250,6 +283,10 @@ impl MePool {
         }
 
         for attempt in 0..fast_retries {
+            if total_attempts >= ME_REFILL_TOTAL_ATTEMPT_CAP {
+                break;
+            }
+            total_attempts = total_attempts.saturating_add(1);
             self.stats.increment_me_reconnect_attempt();
             if self
                 .connect_endpoints_round_robin(writer_dc, &dc_endpoints, self.rng.as_ref())

src/transport/middle_proxy/pool_reinit.rs

@@ -37,16 +37,23 @@ impl MePool {
     }
 
     fn clear_pending_hardswap_state(&self) {
-        self.pending_hardswap_generation.store(0, Ordering::Relaxed);
-        self.pending_hardswap_started_at_epoch_secs
+        self.reinit
+            .pending_hardswap_generation
             .store(0, Ordering::Relaxed);
-        self.pending_hardswap_map_hash.store(0, Ordering::Relaxed);
-        self.warm_generation.store(0, Ordering::Relaxed);
+        self.reinit
+            .pending_hardswap_started_at_epoch_secs
+            .store(0, Ordering::Relaxed);
+        self.reinit
+            .pending_hardswap_map_hash
+            .store(0, Ordering::Relaxed);
+        self.reinit.warm_generation.store(0, Ordering::Relaxed);
     }
 
     async fn promote_warm_generation_to_active(&self, generation: u64) {
-        self.active_generation.store(generation, Ordering::Relaxed);
-        self.warm_generation.store(0, Ordering::Relaxed);
+        self.reinit
+            .active_generation
+            .store(generation, Ordering::Relaxed);
+        self.reinit.warm_generation.store(0, Ordering::Relaxed);
 
         let ws = self.writers.read().await;
         for writer in ws.iter() {
@@ -184,8 +191,14 @@ impl MePool {
     }
 
     fn hardswap_warmup_connect_delay_ms(&self) -> u64 {
-        let min_ms = self.me_hardswap_warmup_delay_min_ms.load(Ordering::Relaxed);
-        let max_ms = self.me_hardswap_warmup_delay_max_ms.load(Ordering::Relaxed);
+        let min_ms = self
+            .reinit
+            .me_hardswap_warmup_delay_min_ms
+            .load(Ordering::Relaxed);
+        let max_ms = self
+            .reinit
+            .me_hardswap_warmup_delay_max_ms
+            .load(Ordering::Relaxed);
         let (min_ms, max_ms) = if min_ms <= max_ms {
             (min_ms, max_ms)
         } else {
@@ -199,9 +212,11 @@ impl MePool {
 
     fn hardswap_warmup_backoff_ms(&self, pass_idx: usize) -> u64 {
         let base_ms = self
+            .reinit
             .me_hardswap_warmup_pass_backoff_base_ms
             .load(Ordering::Relaxed);
-        let cap_ms = (self.me_reconnect_backoff_cap.as_millis() as u64).max(base_ms);
+        let cap_ms =
+            (self.reconnect_runtime.me_reconnect_backoff_cap.as_millis() as u64).max(base_ms);
         let shift = (pass_idx as u32).min(20);
         let scaled = base_ms.saturating_mul(1u64 << shift);
         let core = scaled.min(cap_ms);
@@ -244,6 +259,7 @@ impl MePool {
         desired_by_dc: &HashMap<i32, HashSet<SocketAddr>>,
     ) {
         let extra_passes = self
+            .reinit
             .me_hardswap_warmup_extra_passes
             .load(Ordering::Relaxed)
             .min(10) as usize;
@@ -369,13 +385,20 @@ impl MePool {
 
         let desired_map_hash = Self::desired_map_hash(&desired_by_dc);
         let previous_generation = self.current_generation();
-        let hardswap = self.hardswap.load(Ordering::Relaxed);
+        let hardswap = self.reinit.hardswap.load(Ordering::Relaxed);
         let generation = if hardswap {
-            let pending_generation = self.pending_hardswap_generation.load(Ordering::Relaxed);
+            let pending_generation = self
+                .reinit
+                .pending_hardswap_generation
+                .load(Ordering::Relaxed);
             let pending_started_at = self
+                .reinit
                 .pending_hardswap_started_at_epoch_secs
                 .load(Ordering::Relaxed);
-            let pending_map_hash = self.pending_hardswap_map_hash.load(Ordering::Relaxed);
+            let pending_map_hash = self
+                .reinit
+                .pending_hardswap_map_hash
+                .load(Ordering::Relaxed);
             let pending_age_secs = now_epoch_secs.saturating_sub(pending_started_at);
             let pending_ttl_expired =
                 pending_started_at > 0 && pending_age_secs > ME_HARDSWAP_PENDING_TTL_SECS;
@@ -405,24 +428,30 @@ impl MePool {
                         "ME hardswap pending generation expired by TTL; starting fresh generation"
                     );
                 }
-                let next_generation = self.generation.fetch_add(1, Ordering::Relaxed) + 1;
-                self.pending_hardswap_generation
+                let next_generation = self.reinit.generation.fetch_add(1, Ordering::Relaxed) + 1;
+                self.reinit
+                    .pending_hardswap_generation
                     .store(next_generation, Ordering::Relaxed);
-                self.pending_hardswap_started_at_epoch_secs
+                self.reinit
+                    .pending_hardswap_started_at_epoch_secs
                     .store(now_epoch_secs, Ordering::Relaxed);
-                self.pending_hardswap_map_hash
+                self.reinit
+                    .pending_hardswap_map_hash
                     .store(desired_map_hash, Ordering::Relaxed);
-                self.warm_generation
+                self.reinit
+                    .warm_generation
                     .store(next_generation, Ordering::Relaxed);
                 next_generation
             }
         } else {
             self.clear_pending_hardswap_state();
-            self.generation.fetch_add(1, Ordering::Relaxed) + 1
+            self.reinit.generation.fetch_add(1, Ordering::Relaxed) + 1
         };
 
         if hardswap {
-            self.warm_generation.store(generation, Ordering::Relaxed);
+            self.reinit
+                .warm_generation
+                .store(generation, Ordering::Relaxed);
             self.warmup_generation_for_all_dcs(rng, generation, &desired_by_dc)
                 .await;
         } else {
@@ -436,7 +465,8 @@ impl MePool {
             .map(|w| (w.writer_dc, w.addr))
             .collect();
         let min_ratio = Self::permille_to_ratio(
-            self.me_pool_min_fresh_ratio_permille
+            self.drain_runtime
+                .me_pool_min_fresh_ratio_permille
                 .load(Ordering::Relaxed),
         );
         let (coverage_ratio, missing_dc) =

src/transport/middle_proxy/pool_runtime_api.rs

@@ -94,9 +94,9 @@ impl MePool {
 
     pub(crate) async fn api_nat_stun_snapshot(&self) -> MeApiNatStunSnapshot {
         let now = Instant::now();
-        let mut configured_servers = if !self.nat_stun_servers.is_empty() {
-            self.nat_stun_servers.clone()
-        } else if let Some(stun) = &self.nat_stun {
+        let mut configured_servers = if !self.nat_runtime.nat_stun_servers.is_empty() {
+            self.nat_runtime.nat_stun_servers.clone()
+        } else if let Some(stun) = &self.nat_runtime.nat_stun {
             if stun.trim().is_empty() {
                 Vec::new()
             } else {
@@ -108,11 +108,11 @@ impl MePool {
         configured_servers.sort();
         configured_servers.dedup();
 
-        let mut live_servers = self.nat_stun_live_servers.read().await.clone();
+        let mut live_servers = self.nat_runtime.nat_stun_live_servers.read().await.clone();
         live_servers.sort();
         live_servers.dedup();
 
-        let reflection = self.nat_reflection_cache.lock().await;
+        let reflection = self.nat_runtime.nat_reflection_cache.lock().await;
         let reflection_v4 = reflection.v4.map(|(ts, addr)| MeApiNatReflectionSnapshot {
             addr,
             age_secs: now.saturating_duration_since(ts).as_secs(),
@@ -123,17 +123,19 @@ impl MePool {
         });
         drop(reflection);
 
-        let backoff_until = *self.stun_backoff_until.read().await;
+        let backoff_until = *self.nat_runtime.stun_backoff_until.read().await;
         let stun_backoff_remaining_ms = backoff_until.and_then(|until| {
             (until > now).then_some(until.duration_since(now).as_millis() as u64)
         });
 
         MeApiNatStunSnapshot {
-            nat_probe_enabled: self.nat_probe,
+            nat_probe_enabled: self.nat_runtime.nat_probe,
             nat_probe_disabled_runtime: self
+                .nat_runtime
                 .nat_probe_disabled
                 .load(std::sync::atomic::Ordering::Relaxed),
             nat_probe_attempts: self
+                .nat_runtime
                 .nat_probe_attempts
                 .load(std::sync::atomic::Ordering::Relaxed),
             configured_servers,

src/transport/middle_proxy/pool_status.rs

@@ -160,7 +160,7 @@ impl MePool {
 
         let writers = self.writers.read().await.clone();
         let mut live_writers_by_dc = HashMap::<i16, usize>::new();
-        for writer in writers {
+        for writer in writers.iter() {
             if writer.draining.load(Ordering::Relaxed) {
                 continue;
             }
@@ -197,7 +197,7 @@ impl MePool {
 
         let writers = self.writers.read().await.clone();
         let mut live_writers_by_dc = HashMap::<i16, usize>::new();
-        for writer in writers {
+        for writer in writers.iter() {
             if writer.draining.load(Ordering::Relaxed) {
                 continue;
             }
@@ -224,7 +224,10 @@ impl MePool {
     pub(crate) async fn api_status_snapshot(&self) -> MeApiStatusSnapshot {
         let now_epoch_secs = Self::now_epoch_secs();
         let active_generation = self.current_generation();
-        let drain_ttl_secs = self.me_pool_drain_ttl_secs.load(Ordering::Relaxed);
+        let drain_ttl_secs = self
+            .drain_runtime
+            .me_pool_drain_ttl_secs
+            .load(Ordering::Relaxed);
 
         let mut endpoints_by_dc = BTreeMap::<i16, BTreeSet<SocketAddr>>::new();
         if self.decision.ipv4_me {
@@ -255,7 +258,7 @@ impl MePool {
         let mut dc_rtt_agg = HashMap::<i16, (f64, u64)>::new();
         let mut writer_rows = Vec::<MeApiWriterStatusSnapshot>::with_capacity(writers.len());
 
-        for writer in writers {
+        for writer in writers.iter() {
             let endpoint = writer.addr;
             let dc = i16::try_from(writer.writer_dc).ok();
             let draining = writer.draining.load(Ordering::Relaxed);
@@ -336,6 +339,7 @@ impl MePool {
         let mut fresh_alive_writers = 0usize;
         let floor_mode = self.floor_mode();
         let adaptive_cpu_cores = (self
+            .floor_runtime
             .me_adaptive_floor_cpu_cores_effective
             .load(Ordering::Relaxed) as usize)
             .max(1);
@@ -350,22 +354,26 @@ impl MePool {
                 self.required_writers_for_dc_with_floor_mode(endpoint_count, false);
             let floor_min = if endpoint_count <= 1 {
                 (self
+                    .floor_runtime
                     .me_adaptive_floor_min_writers_single_endpoint
                     .load(Ordering::Relaxed) as usize)
                     .max(1)
                     .min(base_required.max(1))
             } else {
                 (self
+                    .floor_runtime
                     .me_adaptive_floor_min_writers_multi_endpoint
                     .load(Ordering::Relaxed) as usize)
                     .max(1)
                     .min(base_required.max(1))
             };
             let extra_per_core = if endpoint_count <= 1 {
-                self.me_adaptive_floor_max_extra_writers_single_per_core
+                self.floor_runtime
+                    .me_adaptive_floor_max_extra_writers_single_per_core
                     .load(Ordering::Relaxed) as usize
             } else {
-                self.me_adaptive_floor_max_extra_writers_multi_per_core
+                self.floor_runtime
+                    .me_adaptive_floor_max_extra_writers_multi_per_core
                     .load(Ordering::Relaxed) as usize
             };
             let floor_max =
@@ -436,6 +444,7 @@ impl MePool {
         let now = Instant::now();
         let now_epoch_secs = Self::now_epoch_secs();
         let pending_started_at = self
+            .reinit
             .pending_hardswap_started_at_epoch_secs
             .load(Ordering::Relaxed);
         let pending_hardswap_age_secs =
@@ -477,119 +486,175 @@ impl MePool {
         }
 
         MeApiRuntimeSnapshot {
-            active_generation: self.active_generation.load(Ordering::Relaxed),
-            warm_generation: self.warm_generation.load(Ordering::Relaxed),
-            pending_hardswap_generation: self.pending_hardswap_generation.load(Ordering::Relaxed),
+            active_generation: self.reinit.active_generation.load(Ordering::Relaxed),
+            warm_generation: self.reinit.warm_generation.load(Ordering::Relaxed),
+            pending_hardswap_generation: self
+                .reinit
+                .pending_hardswap_generation
+                .load(Ordering::Relaxed),
             pending_hardswap_age_secs,
-            hardswap_enabled: self.hardswap.load(Ordering::Relaxed),
+            hardswap_enabled: self.reinit.hardswap.load(Ordering::Relaxed),
             floor_mode: floor_mode_label(self.floor_mode()),
-            adaptive_floor_idle_secs: self.me_adaptive_floor_idle_secs.load(Ordering::Relaxed),
+            adaptive_floor_idle_secs: self
+                .floor_runtime
+                .me_adaptive_floor_idle_secs
+                .load(Ordering::Relaxed),
             adaptive_floor_min_writers_single_endpoint: self
+                .floor_runtime
                 .me_adaptive_floor_min_writers_single_endpoint
                 .load(Ordering::Relaxed),
             adaptive_floor_min_writers_multi_endpoint: self
+                .floor_runtime
                 .me_adaptive_floor_min_writers_multi_endpoint
                 .load(Ordering::Relaxed),
             adaptive_floor_recover_grace_secs: self
+                .floor_runtime
                 .me_adaptive_floor_recover_grace_secs
                 .load(Ordering::Relaxed),
             adaptive_floor_writers_per_core_total: self
+                .floor_runtime
                 .me_adaptive_floor_writers_per_core_total
                 .load(Ordering::Relaxed) as u16,
             adaptive_floor_cpu_cores_override: self
+                .floor_runtime
                 .me_adaptive_floor_cpu_cores_override
                 .load(Ordering::Relaxed) as u16,
             adaptive_floor_max_extra_writers_single_per_core: self
+                .floor_runtime
                 .me_adaptive_floor_max_extra_writers_single_per_core
                 .load(Ordering::Relaxed)
                 as u16,
             adaptive_floor_max_extra_writers_multi_per_core: self
+                .floor_runtime
                 .me_adaptive_floor_max_extra_writers_multi_per_core
                 .load(Ordering::Relaxed)
                 as u16,
             adaptive_floor_max_active_writers_per_core: self
+                .floor_runtime
                 .me_adaptive_floor_max_active_writers_per_core
                 .load(Ordering::Relaxed)
                 as u16,
             adaptive_floor_max_warm_writers_per_core: self
+                .floor_runtime
                 .me_adaptive_floor_max_warm_writers_per_core
                 .load(Ordering::Relaxed)
                 as u16,
             adaptive_floor_max_active_writers_global: self
+                .floor_runtime
                 .me_adaptive_floor_max_active_writers_global
                 .load(Ordering::Relaxed),
             adaptive_floor_max_warm_writers_global: self
+                .floor_runtime
                 .me_adaptive_floor_max_warm_writers_global
                 .load(Ordering::Relaxed),
             adaptive_floor_cpu_cores_detected: self
+                .floor_runtime
                 .me_adaptive_floor_cpu_cores_detected
                 .load(Ordering::Relaxed),
             adaptive_floor_cpu_cores_effective: self
+                .floor_runtime
                 .me_adaptive_floor_cpu_cores_effective
                 .load(Ordering::Relaxed),
             adaptive_floor_global_cap_raw: self
+                .floor_runtime
                 .me_adaptive_floor_global_cap_raw
                 .load(Ordering::Relaxed),
             adaptive_floor_global_cap_effective: self
+                .floor_runtime
                 .me_adaptive_floor_global_cap_effective
                 .load(Ordering::Relaxed),
             adaptive_floor_target_writers_total: self
+                .floor_runtime
                 .me_adaptive_floor_target_writers_total
                 .load(Ordering::Relaxed),
             adaptive_floor_active_cap_configured: self
+                .floor_runtime
                 .me_adaptive_floor_active_cap_configured
                 .load(Ordering::Relaxed),
             adaptive_floor_active_cap_effective: self
+                .floor_runtime
                 .me_adaptive_floor_active_cap_effective
                 .load(Ordering::Relaxed),
             adaptive_floor_warm_cap_configured: self
+                .floor_runtime
                 .me_adaptive_floor_warm_cap_configured
                 .load(Ordering::Relaxed),
             adaptive_floor_warm_cap_effective: self
+                .floor_runtime
                 .me_adaptive_floor_warm_cap_effective
                 .load(Ordering::Relaxed),
             adaptive_floor_active_writers_current: self
+                .floor_runtime
                 .me_adaptive_floor_active_writers_current
                 .load(Ordering::Relaxed),
             adaptive_floor_warm_writers_current: self
+                .floor_runtime
                 .me_adaptive_floor_warm_writers_current
                 .load(Ordering::Relaxed),
-            me_keepalive_enabled: self.me_keepalive_enabled,
-            me_keepalive_interval_secs: self.me_keepalive_interval.as_secs(),
-            me_keepalive_jitter_secs: self.me_keepalive_jitter.as_secs(),
-            me_keepalive_payload_random: self.me_keepalive_payload_random,
-            rpc_proxy_req_every_secs: self.rpc_proxy_req_every_secs.load(Ordering::Relaxed),
-            me_reconnect_max_concurrent_per_dc: self.me_reconnect_max_concurrent_per_dc,
-            me_reconnect_backoff_base_ms: self.me_reconnect_backoff_base.as_millis() as u64,
-            me_reconnect_backoff_cap_ms: self.me_reconnect_backoff_cap.as_millis() as u64,
-            me_reconnect_fast_retry_count: self.me_reconnect_fast_retry_count,
-            me_pool_drain_ttl_secs: self.me_pool_drain_ttl_secs.load(Ordering::Relaxed),
-            me_pool_force_close_secs: self.me_pool_force_close_secs.load(Ordering::Relaxed),
+            me_keepalive_enabled: self.writer_lifecycle.me_keepalive_enabled,
+            me_keepalive_interval_secs: self.writer_lifecycle.me_keepalive_interval.as_secs(),
+            me_keepalive_jitter_secs: self.writer_lifecycle.me_keepalive_jitter.as_secs(),
+            me_keepalive_payload_random: self.writer_lifecycle.me_keepalive_payload_random,
+            rpc_proxy_req_every_secs: self
+                .writer_lifecycle
+                .rpc_proxy_req_every_secs
+                .load(Ordering::Relaxed),
+            me_reconnect_max_concurrent_per_dc: self
+                .reconnect_runtime
+                .me_reconnect_max_concurrent_per_dc,
+            me_reconnect_backoff_base_ms: self
+                .reconnect_runtime
+                .me_reconnect_backoff_base
+                .as_millis() as u64,
+            me_reconnect_backoff_cap_ms: self.reconnect_runtime.me_reconnect_backoff_cap.as_millis()
+                as u64,
+            me_reconnect_fast_retry_count: self.reconnect_runtime.me_reconnect_fast_retry_count,
+            me_pool_drain_ttl_secs: self
+                .drain_runtime
+                .me_pool_drain_ttl_secs
+                .load(Ordering::Relaxed),
+            me_pool_force_close_secs: self
+                .drain_runtime
+                .me_pool_force_close_secs
+                .load(Ordering::Relaxed),
             me_pool_min_fresh_ratio: Self::permille_to_ratio(
-                self.me_pool_min_fresh_ratio_permille
+                self.drain_runtime
+                    .me_pool_min_fresh_ratio_permille
                     .load(Ordering::Relaxed),
             ),
             me_bind_stale_mode: bind_stale_mode_label(self.bind_stale_mode()),
-            me_bind_stale_ttl_secs: self.me_bind_stale_ttl_secs.load(Ordering::Relaxed),
+            me_bind_stale_ttl_secs: self
+                .binding_policy
+                .me_bind_stale_ttl_secs
+                .load(Ordering::Relaxed),
             me_single_endpoint_shadow_writers: self
+                .single_endpoint_runtime
                 .me_single_endpoint_shadow_writers
                 .load(Ordering::Relaxed),
             me_single_endpoint_outage_mode_enabled: self
+                .single_endpoint_runtime
                 .me_single_endpoint_outage_mode_enabled
                 .load(Ordering::Relaxed),
             me_single_endpoint_outage_disable_quarantine: self
+                .single_endpoint_runtime
                 .me_single_endpoint_outage_disable_quarantine
                 .load(Ordering::Relaxed),
             me_single_endpoint_outage_backoff_min_ms: self
+                .single_endpoint_runtime
                 .me_single_endpoint_outage_backoff_min_ms
                 .load(Ordering::Relaxed),
             me_single_endpoint_outage_backoff_max_ms: self
+                .single_endpoint_runtime
                 .me_single_endpoint_outage_backoff_max_ms
                 .load(Ordering::Relaxed),
             me_single_endpoint_shadow_rotate_every_secs: self
+                .single_endpoint_runtime
                 .me_single_endpoint_shadow_rotate_every_secs
                 .load(Ordering::Relaxed),
-            me_deterministic_writer_sort: self.me_deterministic_writer_sort.load(Ordering::Relaxed),
+            me_deterministic_writer_sort: self
+                .writer_selection_policy
+                .me_deterministic_writer_sort
+                .load(Ordering::Relaxed),
             me_writer_pick_mode: writer_pick_mode_label(self.writer_pick_mode()),
             me_writer_pick_sample_size: self.writer_pick_sample_size() as u8,
             me_socks_kdf_policy: socks_kdf_policy_label(self.socks_kdf_policy()),

src/transport/middle_proxy/pool_writer.rs

@@ -1,3 +1,4 @@
+use std::collections::HashMap;
 use std::io::ErrorKind;
 use std::net::SocketAddr;
 use std::sync::Arc;
@@ -25,6 +26,7 @@ const ME_ACTIVE_PING_SECS: u64 = 25;
 const ME_ACTIVE_PING_JITTER_SECS: i64 = 5;
 const ME_IDLE_KEEPALIVE_MAX_SECS: u64 = 5;
 const ME_RPC_PROXY_REQ_RESPONSE_WAIT_MS: u64 = 700;
+const ME_PING_TRACKER_CLEANUP_EVERY: u32 = 32;
 
 #[derive(Clone, Copy)]
 enum WriterTeardownMode {
@@ -36,6 +38,240 @@ fn is_me_peer_closed_error(error: &ProxyError) -> bool {
     matches!(error, ProxyError::Io(ioe) if ioe.kind() == ErrorKind::UnexpectedEof)
 }
 
+enum WriterLifecycleExit {
+    Reader(Result<()>),
+    Writer(Result<()>),
+    Ping,
+    Signal,
+    Cancelled,
+}
+
+async fn writer_command_loop(
+    mut rx: mpsc::Receiver<WriterCommand>,
+    mut rpc_writer: RpcWriter,
+    cancel: CancellationToken,
+) -> Result<()> {
+    loop {
+        tokio::select! {
+            cmd = rx.recv() => {
+                match cmd {
+                    Some(WriterCommand::Data(payload)) => {
+                        rpc_writer.send(&payload).await?;
+                    }
+                    Some(WriterCommand::DataAndFlush(payload)) => {
+                        rpc_writer.send_and_flush(&payload).await?;
+                    }
+                    Some(WriterCommand::Close) | None => return Ok(()),
+                }
+            }
+            _ = cancel.cancelled() => return Ok(()),
+        }
+    }
+}
+
+#[allow(clippy::too_many_arguments)]
+async fn ping_loop(
+    pool_ping: std::sync::Weak<MePool>,
+    writer_id: u64,
+    tx_ping: mpsc::Sender<WriterCommand>,
+    ping_tracker_ping: Arc<tokio::sync::Mutex<HashMap<i64, Instant>>>,
+    stats_ping: Arc<crate::stats::Stats>,
+    keepalive_enabled: bool,
+    keepalive_interval: Duration,
+    keepalive_jitter: Duration,
+    cancel_ping_token: CancellationToken,
+) {
+    let mut ping_id: i64 = rand::random::<i64>();
+    let mut cleanup_tick: u32 = 0;
+    let idle_interval_cap = Duration::from_secs(ME_IDLE_KEEPALIVE_MAX_SECS);
+    // Per-writer jittered start to avoid phase sync.
+    let startup_jitter = if keepalive_enabled {
+        let mut interval = keepalive_interval;
+        let Some(pool) = pool_ping.upgrade() else {
+            return;
+        };
+        if pool.registry.is_writer_empty(writer_id).await {
+            interval = interval.min(idle_interval_cap);
+        }
+        let jitter_cap_ms = interval.as_millis() / 2;
+        let effective_jitter_ms = keepalive_jitter.as_millis().min(jitter_cap_ms).max(1);
+        Duration::from_millis(rand::rng().random_range(0..=effective_jitter_ms as u64))
+    } else {
+        let jitter =
+            rand::rng().random_range(-ME_ACTIVE_PING_JITTER_SECS..=ME_ACTIVE_PING_JITTER_SECS);
+        let wait = (ME_ACTIVE_PING_SECS as i64 + jitter).max(5) as u64;
+        Duration::from_secs(wait)
+    };
+    tokio::select! {
+        _ = cancel_ping_token.cancelled() => return,
+        _ = tokio::time::sleep(startup_jitter) => {}
+    }
+    loop {
+        let wait = if keepalive_enabled {
+            let mut interval = keepalive_interval;
+            let Some(pool) = pool_ping.upgrade() else {
+                return;
+            };
+            if pool.registry.is_writer_empty(writer_id).await {
+                interval = interval.min(idle_interval_cap);
+            }
+            let jitter_cap_ms = interval.as_millis() / 2;
+            let effective_jitter_ms = keepalive_jitter.as_millis().min(jitter_cap_ms).max(1);
+            interval
+                + Duration::from_millis(rand::rng().random_range(0..=effective_jitter_ms as u64))
+        } else {
+            let jitter =
+                rand::rng().random_range(-ME_ACTIVE_PING_JITTER_SECS..=ME_ACTIVE_PING_JITTER_SECS);
+            let secs = (ME_ACTIVE_PING_SECS as i64 + jitter).max(5) as u64;
+            Duration::from_secs(secs)
+        };
+        tokio::select! {
+            _ = cancel_ping_token.cancelled() => return,
+            _ = tokio::time::sleep(wait) => {}
+        }
+        let sent_id = ping_id;
+        let mut p = Vec::with_capacity(12);
+        p.extend_from_slice(&RPC_PING_U32.to_le_bytes());
+        p.extend_from_slice(&sent_id.to_le_bytes());
+        {
+            let mut tracker = ping_tracker_ping.lock().await;
+            cleanup_tick = cleanup_tick.wrapping_add(1);
+            if cleanup_tick.is_multiple_of(ME_PING_TRACKER_CLEANUP_EVERY) {
+                let before = tracker.len();
+                tracker.retain(|_, ts| ts.elapsed() < Duration::from_secs(120));
+                let expired = before.saturating_sub(tracker.len());
+                if expired > 0 {
+                    stats_ping.increment_me_keepalive_timeout_by(expired as u64);
+                }
+            }
+            tracker.insert(sent_id, std::time::Instant::now());
+        }
+        ping_id = ping_id.wrapping_add(1);
+        stats_ping.increment_me_keepalive_sent();
+        if tx_ping
+            .send(WriterCommand::DataAndFlush(Bytes::from(p)))
+            .await
+            .is_err()
+        {
+            stats_ping.increment_me_keepalive_failed();
+            debug!("ME ping failed, removing dead writer");
+            return;
+        }
+    }
+}
+
+#[allow(clippy::too_many_arguments)]
+async fn rpc_proxy_req_signal_loop(
+    pool_signal: std::sync::Weak<MePool>,
+    writer_id: u64,
+    tx_signal: mpsc::Sender<WriterCommand>,
+    stats_signal: Arc<crate::stats::Stats>,
+    cancel_signal: CancellationToken,
+    keepalive_jitter_signal: Duration,
+    rpc_proxy_req_every_secs: u64,
+) {
+    if rpc_proxy_req_every_secs == 0 {
+        // Disabled service signal loop must stay parked until writer cancellation.
+        // Returning immediately here would complete `select!` and tear down writer lifecycle.
+        cancel_signal.cancelled().await;
+        return;
+    }
+
+    let interval = Duration::from_secs(rpc_proxy_req_every_secs);
+    let startup_jitter_ms = {
+        let jitter_cap_ms = interval.as_millis() / 2;
+        let effective_jitter_ms = keepalive_jitter_signal
+            .as_millis()
+            .min(jitter_cap_ms)
+            .max(1);
+        rand::rng().random_range(0..=effective_jitter_ms as u64)
+    };
+
+    tokio::select! {
+        _ = cancel_signal.cancelled() => return,
+        _ = tokio::time::sleep(Duration::from_millis(startup_jitter_ms)) => {}
+    }
+
+    loop {
+        let wait = {
+            let jitter_cap_ms = interval.as_millis() / 2;
+            let effective_jitter_ms = keepalive_jitter_signal
+                .as_millis()
+                .min(jitter_cap_ms)
+                .max(1);
+            interval
+                + Duration::from_millis(rand::rng().random_range(0..=effective_jitter_ms as u64))
+        };
+
+        tokio::select! {
+            _ = cancel_signal.cancelled() => return,
+            _ = tokio::time::sleep(wait) => {}
+        }
+
+        let Some(pool) = pool_signal.upgrade() else {
+            return;
+        };
+
+        let Some(meta) = pool.registry.get_last_writer_meta(writer_id).await else {
+            stats_signal.increment_me_rpc_proxy_req_signal_skipped_no_meta_total();
+            continue;
+        };
+
+        let (conn_id, mut service_rx) = pool.registry.register().await;
+        // Service RPC_PROXY_REQ signal path is intentionally route-only:
+        // do not bind synthetic conn_id into regular writer/client accounting.
+
+        let payload = build_proxy_req_payload(
+            conn_id,
+            meta.client_addr,
+            meta.our_addr,
+            &[],
+            pool.proxy_tag.as_deref(),
+            meta.proto_flags,
+        );
+
+        if tx_signal
+            .send(WriterCommand::DataAndFlush(payload))
+            .await
+            .is_err()
+        {
+            stats_signal.increment_me_rpc_proxy_req_signal_failed_total();
+            let _ = pool.registry.unregister(conn_id).await;
+            return;
+        }
+
+        stats_signal.increment_me_rpc_proxy_req_signal_sent_total();
+
+        if matches!(
+            tokio::time::timeout(
+                Duration::from_millis(ME_RPC_PROXY_REQ_RESPONSE_WAIT_MS),
+                service_rx.recv(),
+            )
+            .await,
+            Ok(Some(_))
+        ) {
+            stats_signal.increment_me_rpc_proxy_req_signal_response_total();
+        }
+
+        let mut close_payload = Vec::with_capacity(12);
+        close_payload.extend_from_slice(&RPC_CLOSE_EXT_U32.to_le_bytes());
+        close_payload.extend_from_slice(&conn_id.to_le_bytes());
+
+        if tx_signal
+            .send(WriterCommand::DataAndFlush(Bytes::from(close_payload)))
+            .await
+            .is_err()
+        {
+            stats_signal.increment_me_rpc_proxy_req_signal_failed_total();
+            let _ = pool.registry.unregister(conn_id).await;
+            return;
+        }
+
+        stats_signal.increment_me_rpc_proxy_req_signal_close_sent_total();
+        let _ = pool.registry.unregister(conn_id).await;
+    }
+}
+
 impl MePool {
     pub(crate) async fn prune_closed_writers(self: &Arc<Self>) {
         let closed_writer_ids: Vec<u64> = {
@@ -136,46 +372,15 @@ impl MePool {
         let draining_started_at_epoch_secs = Arc::new(AtomicU64::new(0));
         let drain_deadline_epoch_secs = Arc::new(AtomicU64::new(0));
         let allow_drain_fallback = Arc::new(AtomicBool::new(false));
-        let (tx, mut rx) = mpsc::channel::<WriterCommand>(self.writer_cmd_channel_capacity);
-        let mut rpc_writer = RpcWriter {
+        let (tx, rx) =
+            mpsc::channel::<WriterCommand>(self.writer_lifecycle.writer_cmd_channel_capacity);
+        let rpc_writer = RpcWriter {
             writer: hs.wr,
             key: hs.write_key,
             iv: hs.write_iv,
             seq_no: 0,
             crc_mode: hs.crc_mode,
         };
-        let cancel_wr = cancel.clone();
-        let cleanup_done = Arc::new(AtomicBool::new(false));
-        let cleanup_for_writer = cleanup_done.clone();
-        let pool_writer_task = Arc::downgrade(self);
-        tokio::spawn(async move {
-            loop {
-                tokio::select! {
-                    cmd = rx.recv() => {
-                        match cmd {
-                            Some(WriterCommand::Data(payload)) => {
-                                if rpc_writer.send(&payload).await.is_err() { break; }
-                            }
-                            Some(WriterCommand::DataAndFlush(payload)) => {
-                                if rpc_writer.send_and_flush(&payload).await.is_err() { break; }
-                            }
-                            Some(WriterCommand::Close) | None => break,
-                        }
-                    }
-                    _ = cancel_wr.cancelled() => break,
-                }
-            }
-            if cleanup_for_writer
-                .compare_exchange(false, true, Ordering::AcqRel, Ordering::Relaxed)
-                .is_ok()
-            {
-                if let Some(pool) = pool_writer_task.upgrade() {
-                    pool.remove_writer_and_close_clients(writer_id).await;
-                } else {
-                    cancel_wr.cancel();
-                }
-            }
-        });
         let writer = MeWriter {
             id: writer_id,
             addr,
@@ -193,329 +398,135 @@ impl MePool {
             drain_deadline_epoch_secs: drain_deadline_epoch_secs.clone(),
             allow_drain_fallback: allow_drain_fallback.clone(),
         };
-        self.writers.write().await.push(writer.clone());
+        self.writers
+            .update(|writers| writers.push(writer.clone()))
+            .await;
         self.registry.register_writer(writer_id, tx.clone()).await;
         self.registry.mark_writer_idle(writer_id).await;
         self.conn_count.fetch_add(1, Ordering::Relaxed);
-        self.writer_available.notify_one();
+        self.notify_writer_epoch();
 
         let reg = self.registry.clone();
         let writers_arc = self.writers_arc();
-        let ping_tracker = self.ping_tracker.clone();
+        let ping_tracker = Arc::new(tokio::sync::Mutex::new(HashMap::<i64, Instant>::new()));
         let ping_tracker_reader = ping_tracker.clone();
+        let ping_tracker_ping = ping_tracker.clone();
         let rtt_stats = self.rtt_stats.clone();
         let stats_reader = self.stats.clone();
         let stats_reader_close = self.stats.clone();
         let stats_ping = self.stats.clone();
-        let pool = Arc::downgrade(self);
-        let cancel_ping = cancel.clone();
-        let tx_ping = tx.clone();
-        let ping_tracker_ping = ping_tracker.clone();
-        let cleanup_for_reader = cleanup_done.clone();
-        let cleanup_for_ping = cleanup_done.clone();
-        let keepalive_enabled = self.me_keepalive_enabled;
-        let keepalive_interval = self.me_keepalive_interval;
-        let keepalive_jitter = self.me_keepalive_jitter;
-        let rpc_proxy_req_every_secs = self.rpc_proxy_req_every_secs.load(Ordering::Relaxed);
-        let tx_signal = tx.clone();
         let stats_signal = self.stats.clone();
-        let cancel_signal = cancel.clone();
-        let cleanup_for_signal = cleanup_done.clone();
-        let pool_signal = Arc::downgrade(self);
-        let keepalive_jitter_signal = self.me_keepalive_jitter;
-        let cancel_reader_token = cancel.clone();
-        let cancel_ping_token = cancel_ping.clone();
-        let reader_route_data_wait_ms = self.me_reader_route_data_wait_ms.clone();
-
-        tokio::spawn(async move {
-            let res = reader_loop(
-                hs.rd,
-                hs.read_key,
-                hs.read_iv,
-                hs.crc_mode,
-                reg.clone(),
-                BytesMut::new(),
-                BytesMut::new(),
-                tx.clone(),
-                ping_tracker_reader,
-                rtt_stats.clone(),
-                stats_reader,
-                writer_id,
-                degraded.clone(),
-                rtt_ema_ms_x10.clone(),
-                reader_route_data_wait_ms,
-                cancel_reader_token.clone(),
-            )
-            .await;
-            let idle_close_by_peer = if let Err(e) = res.as_ref() {
-                is_me_peer_closed_error(e) && reg.is_writer_empty(writer_id).await
-            } else {
-                false
-            };
-            if idle_close_by_peer {
-                stats_reader_close.increment_me_idle_close_by_peer_total();
-                info!(writer_id, "ME socket closed by peer on idle writer");
-            }
-            if cleanup_for_reader
-                .compare_exchange(false, true, Ordering::AcqRel, Ordering::Relaxed)
-                .is_ok()
-            {
-                if let Some(pool) = pool.upgrade() {
-                    pool.remove_writer_and_close_clients(writer_id).await;
-                } else {
-                    // Fallback for shutdown races: make writer task exit quickly so stale
-                    // channels are observable by periodic prune.
-                    cancel_reader_token.cancel();
-                }
-            }
-            if let Err(e) = res
-                && !idle_close_by_peer
-            {
-                warn!(error = %e, "ME reader ended");
-            }
-            let remaining = writers_arc.read().await.len();
-            debug!(writer_id, remaining, "ME reader task finished");
-        });
-
+        let pool_lifecycle = Arc::downgrade(self);
         let pool_ping = Arc::downgrade(self);
+        let pool_signal = Arc::downgrade(self);
+        let tx_reader = tx.clone();
+        let tx_ping = tx.clone();
+        let tx_signal = tx.clone();
+        let keepalive_enabled = self.writer_lifecycle.me_keepalive_enabled;
+        let keepalive_interval = self.writer_lifecycle.me_keepalive_interval;
+        let keepalive_jitter = self.writer_lifecycle.me_keepalive_jitter;
+        let keepalive_jitter_signal = self.writer_lifecycle.me_keepalive_jitter;
+        let rpc_proxy_req_every_secs = self
+            .writer_lifecycle
+            .rpc_proxy_req_every_secs
+            .load(Ordering::Relaxed);
+        let cancel_reader = cancel.clone();
+        let cancel_writer = cancel.clone();
+        let cancel_ping = cancel.clone();
+        let cancel_signal = cancel.clone();
+        let cancel_select = cancel.clone();
+        let cancel_cleanup = cancel.clone();
+        let reader_route_data_wait_ms = self.transport_policy.me_reader_route_data_wait_ms.clone();
+
         tokio::spawn(async move {
-            let mut ping_id: i64 = rand::random::<i64>();
-            let idle_interval_cap = Duration::from_secs(ME_IDLE_KEEPALIVE_MAX_SECS);
-            // Per-writer jittered start to avoid phase sync.
-            let startup_jitter = if keepalive_enabled {
-                let mut interval = keepalive_interval;
-                if let Some(pool) = pool_ping.upgrade() {
-                    if pool.registry.is_writer_empty(writer_id).await {
-                        interval = interval.min(idle_interval_cap);
-                    }
-                } else {
-                    return;
+            // Reader MUST be the first branch in biased select! to avoid read starvation.
+            let exit = tokio::select! {
+                biased;
+
+                reader_res = reader_loop(
+                    hs.rd,
+                    hs.read_key,
+                    hs.read_iv,
+                    hs.crc_mode,
+                    reg.clone(),
+                    BytesMut::new(),
+                    BytesMut::new(),
+                    tx_reader,
+                    ping_tracker_reader,
+                    rtt_stats,
+                    stats_reader,
+                    writer_id,
+                    degraded,
+                    rtt_ema_ms_x10,
+                    reader_route_data_wait_ms,
+                    cancel_reader,
+                ) => WriterLifecycleExit::Reader(reader_res),
+                writer_res = writer_command_loop(rx, rpc_writer, cancel_writer) => {
+                    WriterLifecycleExit::Writer(writer_res)
                 }
-                let jitter_cap_ms = interval.as_millis() / 2;
-                let effective_jitter_ms = keepalive_jitter.as_millis().min(jitter_cap_ms).max(1);
-                Duration::from_millis(rand::rng().random_range(0..=effective_jitter_ms as u64))
-            } else {
-                let jitter = rand::rng()
-                    .random_range(-ME_ACTIVE_PING_JITTER_SECS..=ME_ACTIVE_PING_JITTER_SECS);
-                let wait = (ME_ACTIVE_PING_SECS as i64 + jitter).max(5) as u64;
-                Duration::from_secs(wait)
+                _ = ping_loop(
+                    pool_ping,
+                    writer_id,
+                    tx_ping,
+                    ping_tracker_ping,
+                    stats_ping,
+                    keepalive_enabled,
+                    keepalive_interval,
+                    keepalive_jitter,
+                    cancel_ping,
+                ) => WriterLifecycleExit::Ping,
+                _ = rpc_proxy_req_signal_loop(
+                    pool_signal,
+                    writer_id,
+                    tx_signal,
+                    stats_signal,
+                    cancel_signal,
+                    keepalive_jitter_signal,
+                    rpc_proxy_req_every_secs,
+                ) => WriterLifecycleExit::Signal,
+                _ = cancel_select.cancelled() => WriterLifecycleExit::Cancelled,
             };
-            tokio::select! {
-                _ = cancel_ping_token.cancelled() => return,
-                _ = tokio::time::sleep(startup_jitter) => {}
-            }
-            loop {
-                let wait = if keepalive_enabled {
-                    let mut interval = keepalive_interval;
-                    if let Some(pool) = pool_ping.upgrade() {
-                        if pool.registry.is_writer_empty(writer_id).await {
-                            interval = interval.min(idle_interval_cap);
-                        }
+
+            match exit {
+                WriterLifecycleExit::Reader(res) => {
+                    let idle_close_by_peer = if let Err(e) = res.as_ref() {
+                        is_me_peer_closed_error(e) && reg.is_writer_empty(writer_id).await
                     } else {
-                        break;
+                        false
+                    };
+                    if idle_close_by_peer {
+                        stats_reader_close.increment_me_idle_close_by_peer_total();
+                        info!(writer_id, "ME socket closed by peer on idle writer");
                     }
-                    let jitter_cap_ms = interval.as_millis() / 2;
-                    let effective_jitter_ms =
-                        keepalive_jitter.as_millis().min(jitter_cap_ms).max(1);
-                    interval
-                        + Duration::from_millis(
-                            rand::rng().random_range(0..=effective_jitter_ms as u64),
-                        )
-                } else {
-                    let jitter = rand::rng()
-                        .random_range(-ME_ACTIVE_PING_JITTER_SECS..=ME_ACTIVE_PING_JITTER_SECS);
-                    let secs = (ME_ACTIVE_PING_SECS as i64 + jitter).max(5) as u64;
-                    Duration::from_secs(secs)
-                };
-                tokio::select! {
-                    _ = cancel_ping_token.cancelled() => {
-                        break;
-                    }
-                    _ = tokio::time::sleep(wait) => {}
-                }
-                let sent_id = ping_id;
-                let mut p = Vec::with_capacity(12);
-                p.extend_from_slice(&RPC_PING_U32.to_le_bytes());
-                p.extend_from_slice(&sent_id.to_le_bytes());
-                {
-                    let mut tracker = ping_tracker_ping.lock().await;
-                    let now_epoch_ms = std::time::SystemTime::now()
-                        .duration_since(std::time::UNIX_EPOCH)
-                        .unwrap_or_default()
-                        .as_millis() as u64;
-                    let mut run_cleanup = false;
-                    if let Some(pool) = pool_ping.upgrade() {
-                        let last_cleanup_ms = pool
-                            .ping_tracker_last_cleanup_epoch_ms
-                            .load(Ordering::Relaxed);
-                        if now_epoch_ms.saturating_sub(last_cleanup_ms) >= 30_000
-                            && pool
-                                .ping_tracker_last_cleanup_epoch_ms
-                                .compare_exchange(
-                                    last_cleanup_ms,
-                                    now_epoch_ms,
-                                    Ordering::AcqRel,
-                                    Ordering::Relaxed,
-                                )
-                                .is_ok()
-                        {
-                            run_cleanup = true;
-                        }
-                    }
-
-                    if run_cleanup {
-                        let before = tracker.len();
-                        tracker.retain(|_, (ts, _)| ts.elapsed() < Duration::from_secs(120));
-                        let expired = before.saturating_sub(tracker.len());
-                        if expired > 0 {
-                            stats_ping.increment_me_keepalive_timeout_by(expired as u64);
-                        }
-                    }
-                    tracker.insert(sent_id, (std::time::Instant::now(), writer_id));
-                }
-                ping_id = ping_id.wrapping_add(1);
-                stats_ping.increment_me_keepalive_sent();
-                if tx_ping
-                    .send(WriterCommand::DataAndFlush(Bytes::from(p)))
-                    .await
-                    .is_err()
-                {
-                    stats_ping.increment_me_keepalive_failed();
-                    debug!("ME ping failed, removing dead writer");
-                    cancel_ping.cancel();
-                    if cleanup_for_ping
-                        .compare_exchange(false, true, Ordering::AcqRel, Ordering::Relaxed)
-                        .is_ok()
-                        && let Some(pool) = pool_ping.upgrade()
+                    if let Err(e) = res
+                        && !idle_close_by_peer
                     {
-                        pool.remove_writer_and_close_clients(writer_id).await;
+                        warn!(error = %e, "ME reader ended");
                     }
-                    break;
                 }
-            }
-        });
-
-        tokio::spawn(async move {
-            if rpc_proxy_req_every_secs == 0 {
-                return;
-            }
-
-            let interval = Duration::from_secs(rpc_proxy_req_every_secs);
-            let startup_jitter_ms = {
-                let jitter_cap_ms = interval.as_millis() / 2;
-                let effective_jitter_ms = keepalive_jitter_signal
-                    .as_millis()
-                    .min(jitter_cap_ms)
-                    .max(1);
-                rand::rng().random_range(0..=effective_jitter_ms as u64)
-            };
-
-            tokio::select! {
-                _ = cancel_signal.cancelled() => return,
-                _ = tokio::time::sleep(Duration::from_millis(startup_jitter_ms)) => {}
-            }
-
-            loop {
-                let wait = {
-                    let jitter_cap_ms = interval.as_millis() / 2;
-                    let effective_jitter_ms = keepalive_jitter_signal
-                        .as_millis()
-                        .min(jitter_cap_ms)
-                        .max(1);
-                    interval
-                        + Duration::from_millis(
-                            rand::rng().random_range(0..=effective_jitter_ms as u64),
-                        )
-                };
-
-                tokio::select! {
-                    _ = cancel_signal.cancelled() => break,
-                    _ = tokio::time::sleep(wait) => {}
-                }
-
-                let Some(pool) = pool_signal.upgrade() else {
-                    break;
-                };
-
-                let Some(meta) = pool.registry.get_last_writer_meta(writer_id).await else {
-                    stats_signal.increment_me_rpc_proxy_req_signal_skipped_no_meta_total();
-                    continue;
-                };
-
-                let (conn_id, mut service_rx) = pool.registry.register().await;
-                if !pool
-                    .registry
-                    .bind_writer(conn_id, writer_id, meta.clone())
-                    .await
-                {
-                    let _ = pool.registry.unregister(conn_id).await;
-                    stats_signal.increment_me_rpc_proxy_req_signal_skipped_no_meta_total();
-                    continue;
-                }
-
-                let payload = build_proxy_req_payload(
-                    conn_id,
-                    meta.client_addr,
-                    meta.our_addr,
-                    &[],
-                    pool.proxy_tag.as_deref(),
-                    meta.proto_flags,
-                );
-
-                if tx_signal
-                    .send(WriterCommand::DataAndFlush(payload))
-                    .await
-                    .is_err()
-                {
-                    stats_signal.increment_me_rpc_proxy_req_signal_failed_total();
-                    let _ = pool.registry.unregister(conn_id).await;
-                    cancel_signal.cancel();
-                    if cleanup_for_signal
-                        .compare_exchange(false, true, Ordering::AcqRel, Ordering::Relaxed)
-                        .is_ok()
-                    {
-                        pool.remove_writer_and_close_clients(writer_id).await;
+                WriterLifecycleExit::Writer(res) => {
+                    if let Err(e) = res {
+                        warn!(error = %e, "ME writer command loop ended");
                     }
-                    break;
                 }
-
-                stats_signal.increment_me_rpc_proxy_req_signal_sent_total();
-
-                if matches!(
-                    tokio::time::timeout(
-                        Duration::from_millis(ME_RPC_PROXY_REQ_RESPONSE_WAIT_MS),
-                        service_rx.recv(),
-                    )
-                    .await,
-                    Ok(Some(_))
-                ) {
-                    stats_signal.increment_me_rpc_proxy_req_signal_response_total();
+                WriterLifecycleExit::Ping => {
+                    debug!(writer_id, "ME ping loop finished");
                 }
-
-                let mut close_payload = Vec::with_capacity(12);
-                close_payload.extend_from_slice(&RPC_CLOSE_EXT_U32.to_le_bytes());
-                close_payload.extend_from_slice(&conn_id.to_le_bytes());
-
-                if tx_signal
-                    .send(WriterCommand::DataAndFlush(Bytes::from(close_payload)))
-                    .await
-                    .is_err()
-                {
-                    stats_signal.increment_me_rpc_proxy_req_signal_failed_total();
-                    let _ = pool.registry.unregister(conn_id).await;
-                    cancel_signal.cancel();
-                    if cleanup_for_signal
-                        .compare_exchange(false, true, Ordering::AcqRel, Ordering::Relaxed)
-                        .is_ok()
-                    {
-                        pool.remove_writer_and_close_clients(writer_id).await;
-                    }
-                    break;
+                WriterLifecycleExit::Signal => {
+                    debug!(writer_id, "ME rpc_proxy_req signal loop finished");
                 }
-
-                stats_signal.increment_me_rpc_proxy_req_signal_close_sent_total();
-                let _ = pool.registry.unregister(conn_id).await;
+                WriterLifecycleExit::Cancelled => {}
             }
+
+            if let Some(pool) = pool_lifecycle.upgrade() {
+                pool.remove_writer_and_close_clients(writer_id).await;
+            } else {
+                // Fallback for shutdown races: make lifecycle exit observable by prune.
+                cancel_cleanup.cancel();
+            }
+
+            let remaining = writers_arc.read().await.len();
+            debug!(writer_id, remaining, "ME writer lifecycle task finished");
         });
 
         Ok(())
@@ -594,23 +605,36 @@ impl MePool {
         // The close command below is only a best-effort accelerator for task shutdown.
         // Cleanup progress must never depend on command-channel availability.
         let _ = self.registry.writer_lost(writer_id).await;
-        {
-            let mut tracker = self.ping_tracker.lock().await;
-            tracker.retain(|_, (_, wid)| *wid != writer_id);
-        }
         self.rtt_stats.lock().await.remove(&writer_id);
         if let Some(tx) = close_tx {
-            let _ = tx.send(WriterCommand::Close).await;
+            // Keep teardown critical path non-blocking: close is best-effort only.
+            let _ = tx.try_send(WriterCommand::Close);
         }
         if let Some(addr) = removed_addr {
             if let Some(uptime) = removed_uptime {
-                // Quarantine flapping endpoints regardless of draining state.
-                self.maybe_quarantine_flapping_endpoint(addr, uptime).await;
+                // Quarantine contract: only unexpected removals are considered endpoint flap.
+                if trigger_refill {
+                    self.stats
+                        .increment_me_endpoint_quarantine_unexpected_total();
+                    self.maybe_quarantine_flapping_endpoint(addr, uptime, "unexpected")
+                        .await;
+                } else {
+                    self.stats
+                        .increment_me_endpoint_quarantine_draining_suppressed_total();
+                    debug!(
+                        %addr,
+                        uptime_ms = uptime.as_millis(),
+                        "Skipping endpoint quarantine for draining writer removal"
+                    );
+                }
             }
             if trigger_refill && let Some(writer_dc) = removed_dc {
                 self.trigger_immediate_refill_for_dc(addr, writer_dc);
             }
         }
+        if removed {
+            self.notify_writer_epoch();
+        }
         removed
     }
 
@@ -676,7 +700,10 @@ impl MePool {
             MeBindStaleMode::Never => false,
             MeBindStaleMode::Always => true,
             MeBindStaleMode::Ttl => {
-                let ttl_secs = self.me_bind_stale_ttl_secs.load(Ordering::Relaxed);
+                let ttl_secs = self
+                    .binding_policy
+                    .me_bind_stale_ttl_secs
+                    .load(Ordering::Relaxed);
                 if ttl_secs == 0 {
                     return true;
                 }

src/transport/middle_proxy/reader.rs

@@ -32,10 +32,10 @@ pub(crate) async fn reader_loop(
     enc_leftover: BytesMut,
     mut dec: BytesMut,
     tx: mpsc::Sender<WriterCommand>,
-    ping_tracker: Arc<Mutex<HashMap<i64, (Instant, u64)>>>,
+    ping_tracker: Arc<Mutex<HashMap<i64, Instant>>>,
     rtt_stats: Arc<Mutex<HashMap<u64, (f64, f64)>>>,
     stats: Arc<Stats>,
-    _writer_id: u64,
+    writer_id: u64,
     degraded: Arc<AtomicBool>,
     writer_rtt_ema_ms_x10: Arc<AtomicU32>,
     reader_route_data_wait_ms: Arc<AtomicU64>,
@@ -45,7 +45,7 @@ pub(crate) async fn reader_loop(
     let mut expected_seq: i32 = 0;
 
     loop {
-        let mut tmp = [0u8; 16_384];
+        let mut tmp = [0u8; 65_536];
         let n = tokio::select! {
             res = rd.read(&mut tmp) => res.map_err(ProxyError::Io)?,
             _ = cancel.cancelled() => return Ok(()),
@@ -203,13 +203,13 @@ pub(crate) async fn reader_loop(
             } else if pt == RPC_PONG_U32 && body.len() >= 8 {
                 let ping_id = i64::from_le_bytes(body[0..8].try_into().unwrap());
                 stats.increment_me_keepalive_pong();
-                if let Some((sent, wid)) = {
+                if let Some(sent) = {
                     let mut guard = ping_tracker.lock().await;
                     guard.remove(&ping_id)
                 } {
                     let rtt = sent.elapsed().as_secs_f64() * 1000.0;
                     let mut stats = rtt_stats.lock().await;
-                    let entry = stats.entry(wid).or_insert((rtt, rtt));
+                    let entry = stats.entry(writer_id).or_insert((rtt, rtt));
                     entry.1 = entry.1 * 0.8 + rtt * 0.2;
                     if rtt < entry.0 {
                         entry.0 = rtt;
@@ -224,7 +224,7 @@ pub(crate) async fn reader_loop(
                         Ordering::Relaxed,
                     );
                     trace!(
-                        writer_id = wid,
+                        writer_id,
                         rtt_ms = rtt,
                         ema_ms = entry.1,
                         base_ms = entry.0,

src/transport/middle_proxy/registry.rs

@@ -3,8 +3,9 @@ use std::net::SocketAddr;
 use std::sync::atomic::{AtomicU8, AtomicU64, Ordering};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
+use dashmap::DashMap;
 use tokio::sync::mpsc::error::TrySendError;
-use tokio::sync::{RwLock, mpsc};
+use tokio::sync::{Mutex, mpsc};
 
 use super::MeResponse;
 use super::codec::WriterCommand;
@@ -50,8 +51,15 @@ pub(super) struct WriterActivitySnapshot {
     pub active_sessions_by_target_dc: HashMap<i16, usize>,
 }
 
-struct RegistryInner {
-    map: HashMap<u64, mpsc::Sender<MeResponse>>,
+struct RoutingTable {
+    map: DashMap<u64, mpsc::Sender<MeResponse>>,
+}
+
+struct BindingState {
+    inner: Mutex<BindingInner>,
+}
+
+struct BindingInner {
     writers: HashMap<u64, mpsc::Sender<WriterCommand>>,
     writer_for_conn: HashMap<u64, u64>,
     conns_for_writer: HashMap<u64, HashSet<u64>>,
@@ -60,10 +68,9 @@ struct RegistryInner {
     writer_idle_since_epoch_secs: HashMap<u64, u64>,
 }
 
-impl RegistryInner {
+impl BindingInner {
     fn new() -> Self {
         Self {
-            map: HashMap::new(),
             writers: HashMap::new(),
             writer_for_conn: HashMap::new(),
             conns_for_writer: HashMap::new(),
@@ -75,7 +82,8 @@ impl RegistryInner {
 }
 
 pub struct ConnRegistry {
-    inner: RwLock<RegistryInner>,
+    routing: RoutingTable,
+    binding: BindingState,
     next_id: AtomicU64,
     route_channel_capacity: usize,
     route_backpressure_base_timeout_ms: AtomicU64,
@@ -94,7 +102,12 @@ impl ConnRegistry {
     pub fn with_route_channel_capacity(route_channel_capacity: usize) -> Self {
         let start = rand::random::<u64>() | 1;
         Self {
-            inner: RwLock::new(RegistryInner::new()),
+            routing: RoutingTable {
+                map: DashMap::new(),
+            },
+            binding: BindingState {
+                inner: Mutex::new(BindingInner::new()),
+            },
             next_id: AtomicU64::new(start),
             route_channel_capacity: route_channel_capacity.max(1),
             route_backpressure_base_timeout_ms: AtomicU64::new(ROUTE_BACKPRESSURE_BASE_TIMEOUT_MS),
@@ -130,14 +143,14 @@ impl ConnRegistry {
     pub async fn register(&self) -> (u64, mpsc::Receiver<MeResponse>) {
         let id = self.next_id.fetch_add(1, Ordering::Relaxed);
         let (tx, rx) = mpsc::channel(self.route_channel_capacity);
-        self.inner.write().await.map.insert(id, tx);
+        self.routing.map.insert(id, tx);
         (id, rx)
     }
 
     pub async fn register_writer(&self, writer_id: u64, tx: mpsc::Sender<WriterCommand>) {
-        let mut inner = self.inner.write().await;
-        inner.writers.insert(writer_id, tx);
-        inner
+        let mut binding = self.binding.inner.lock().await;
+        binding.writers.insert(writer_id, tx);
+        binding
             .conns_for_writer
             .entry(writer_id)
             .or_insert_with(HashSet::new);
@@ -145,18 +158,18 @@ impl ConnRegistry {
 
     /// Unregister connection, returning associated writer_id if any.
     pub async fn unregister(&self, id: u64) -> Option<u64> {
-        let mut inner = self.inner.write().await;
-        inner.map.remove(&id);
-        inner.meta.remove(&id);
-        if let Some(writer_id) = inner.writer_for_conn.remove(&id) {
-            let became_empty = if let Some(set) = inner.conns_for_writer.get_mut(&writer_id) {
+        self.routing.map.remove(&id);
+        let mut binding = self.binding.inner.lock().await;
+        binding.meta.remove(&id);
+        if let Some(writer_id) = binding.writer_for_conn.remove(&id) {
+            let became_empty = if let Some(set) = binding.conns_for_writer.get_mut(&writer_id) {
                 set.remove(&id);
                 set.is_empty()
             } else {
                 false
             };
             if became_empty {
-                inner
+                binding
                     .writer_idle_since_epoch_secs
                     .insert(writer_id, Self::now_epoch_secs());
             }
@@ -167,10 +180,7 @@ impl ConnRegistry {
 
     #[allow(dead_code)]
     pub async fn route(&self, id: u64, resp: MeResponse) -> RouteResult {
-        let tx = {
-            let inner = self.inner.read().await;
-            inner.map.get(&id).cloned()
-        };
+        let tx = self.routing.map.get(&id).map(|entry| entry.value().clone());
 
         let Some(tx) = tx else {
             return RouteResult::NoConn;
@@ -223,10 +233,7 @@ impl ConnRegistry {
     }
 
     pub async fn route_nowait(&self, id: u64, resp: MeResponse) -> RouteResult {
-        let tx = {
-            let inner = self.inner.read().await;
-            inner.map.get(&id).cloned()
-        };
+        let tx = self.routing.map.get(&id).map(|entry| entry.value().clone());
 
         let Some(tx) = tx else {
             return RouteResult::NoConn;
@@ -249,10 +256,7 @@ impl ConnRegistry {
             return self.route_nowait(id, resp).await;
         }
 
-        let tx = {
-            let inner = self.inner.read().await;
-            inner.map.get(&id).cloned()
-        };
+        let tx = self.routing.map.get(&id).map(|entry| entry.value().clone());
 
         let Some(tx) = tx else {
             return RouteResult::NoConn;
@@ -291,33 +295,39 @@ impl ConnRegistry {
     }
 
     pub async fn bind_writer(&self, conn_id: u64, writer_id: u64, meta: ConnMeta) -> bool {
-        let mut inner = self.inner.write().await;
-        if !inner.writers.contains_key(&writer_id) {
+        let mut binding = self.binding.inner.lock().await;
+        // ROUTING IS THE SOURCE OF TRUTH:
+        // never keep/attach writer binding for a connection that is already
+        // absent from the routing table.
+        if !self.routing.map.contains_key(&conn_id) {
+            return false;
+        }
+        if !binding.writers.contains_key(&writer_id) {
             return false;
         }
 
-        let previous_writer_id = inner.writer_for_conn.insert(conn_id, writer_id);
+        let previous_writer_id = binding.writer_for_conn.insert(conn_id, writer_id);
         if let Some(previous_writer_id) = previous_writer_id
             && previous_writer_id != writer_id
         {
             let became_empty =
-                if let Some(set) = inner.conns_for_writer.get_mut(&previous_writer_id) {
+                if let Some(set) = binding.conns_for_writer.get_mut(&previous_writer_id) {
                     set.remove(&conn_id);
                     set.is_empty()
                 } else {
                     false
                 };
             if became_empty {
-                inner
+                binding
                     .writer_idle_since_epoch_secs
                     .insert(previous_writer_id, Self::now_epoch_secs());
             }
         }
 
-        inner.meta.insert(conn_id, meta.clone());
-        inner.last_meta_for_writer.insert(writer_id, meta);
-        inner.writer_idle_since_epoch_secs.remove(&writer_id);
-        inner
+        binding.meta.insert(conn_id, meta.clone());
+        binding.last_meta_for_writer.insert(writer_id, meta);
+        binding.writer_idle_since_epoch_secs.remove(&writer_id);
+        binding
             .conns_for_writer
             .entry(writer_id)
             .or_insert_with(HashSet::new)
@@ -326,32 +336,32 @@ impl ConnRegistry {
     }
 
     pub async fn mark_writer_idle(&self, writer_id: u64) {
-        let mut inner = self.inner.write().await;
-        inner
+        let mut binding = self.binding.inner.lock().await;
+        binding
             .conns_for_writer
             .entry(writer_id)
             .or_insert_with(HashSet::new);
-        inner
+        binding
             .writer_idle_since_epoch_secs
             .entry(writer_id)
             .or_insert(Self::now_epoch_secs());
     }
 
     pub async fn get_last_writer_meta(&self, writer_id: u64) -> Option<ConnMeta> {
-        let inner = self.inner.read().await;
-        inner.last_meta_for_writer.get(&writer_id).cloned()
+        let binding = self.binding.inner.lock().await;
+        binding.last_meta_for_writer.get(&writer_id).cloned()
     }
 
     pub async fn writer_idle_since_snapshot(&self) -> HashMap<u64, u64> {
-        let inner = self.inner.read().await;
-        inner.writer_idle_since_epoch_secs.clone()
+        let binding = self.binding.inner.lock().await;
+        binding.writer_idle_since_epoch_secs.clone()
     }
 
     pub async fn writer_idle_since_for_writer_ids(&self, writer_ids: &[u64]) -> HashMap<u64, u64> {
-        let inner = self.inner.read().await;
+        let binding = self.binding.inner.lock().await;
         let mut out = HashMap::<u64, u64>::with_capacity(writer_ids.len());
         for writer_id in writer_ids {
-            if let Some(idle_since) = inner.writer_idle_since_epoch_secs.get(writer_id).copied() {
+            if let Some(idle_since) = binding.writer_idle_since_epoch_secs.get(writer_id).copied() {
                 out.insert(*writer_id, idle_since);
             }
         }
@@ -359,14 +369,14 @@ impl ConnRegistry {
     }
 
     pub(super) async fn writer_activity_snapshot(&self) -> WriterActivitySnapshot {
-        let inner = self.inner.read().await;
+        let binding = self.binding.inner.lock().await;
         let mut bound_clients_by_writer = HashMap::<u64, usize>::new();
         let mut active_sessions_by_target_dc = HashMap::<i16, usize>::new();
 
-        for (writer_id, conn_ids) in &inner.conns_for_writer {
+        for (writer_id, conn_ids) in &binding.conns_for_writer {
             bound_clients_by_writer.insert(*writer_id, conn_ids.len());
         }
-        for conn_meta in inner.meta.values() {
+        for conn_meta in binding.meta.values() {
             if conn_meta.target_dc == 0 {
                 continue;
             }
@@ -382,9 +392,39 @@ impl ConnRegistry {
     }
 
     pub async fn get_writer(&self, conn_id: u64) -> Option<ConnWriter> {
-        let inner = self.inner.read().await;
-        let writer_id = inner.writer_for_conn.get(&conn_id).cloned()?;
-        let writer = inner.writers.get(&writer_id).cloned()?;
+        let mut binding = self.binding.inner.lock().await;
+        // ROUTING IS THE SOURCE OF TRUTH:
+        // stale bindings are ignored and lazily cleaned when routing no longer
+        // contains the connection.
+        if !self.routing.map.contains_key(&conn_id) {
+            binding.meta.remove(&conn_id);
+            if let Some(stale_writer_id) = binding.writer_for_conn.remove(&conn_id)
+                && let Some(conns) = binding.conns_for_writer.get_mut(&stale_writer_id)
+            {
+                conns.remove(&conn_id);
+                if conns.is_empty() {
+                    binding
+                        .writer_idle_since_epoch_secs
+                        .insert(stale_writer_id, Self::now_epoch_secs());
+                }
+            }
+            return None;
+        }
+
+        let writer_id = binding.writer_for_conn.get(&conn_id).copied()?;
+        let Some(writer) = binding.writers.get(&writer_id).cloned() else {
+            binding.writer_for_conn.remove(&conn_id);
+            binding.meta.remove(&conn_id);
+            if let Some(conns) = binding.conns_for_writer.get_mut(&writer_id) {
+                conns.remove(&conn_id);
+                if conns.is_empty() {
+                    binding
+                        .writer_idle_since_epoch_secs
+                        .insert(writer_id, Self::now_epoch_secs());
+                }
+            }
+            return None;
+        };
         Some(ConnWriter {
             writer_id,
             tx: writer,
@@ -392,16 +432,16 @@ impl ConnRegistry {
     }
 
     pub async fn active_conn_ids(&self) -> Vec<u64> {
-        let inner = self.inner.read().await;
-        inner.writer_for_conn.keys().copied().collect()
+        let binding = self.binding.inner.lock().await;
+        binding.writer_for_conn.keys().copied().collect()
     }
 
     pub async fn writer_lost(&self, writer_id: u64) -> Vec<BoundConn> {
-        let mut inner = self.inner.write().await;
-        inner.writers.remove(&writer_id);
-        inner.last_meta_for_writer.remove(&writer_id);
-        inner.writer_idle_since_epoch_secs.remove(&writer_id);
-        let conns = inner
+        let mut binding = self.binding.inner.lock().await;
+        binding.writers.remove(&writer_id);
+        binding.last_meta_for_writer.remove(&writer_id);
+        binding.writer_idle_since_epoch_secs.remove(&writer_id);
+        let conns = binding
             .conns_for_writer
             .remove(&writer_id)
             .unwrap_or_default()
@@ -410,11 +450,11 @@ impl ConnRegistry {
 
         let mut out = Vec::new();
         for conn_id in conns {
-            if inner.writer_for_conn.get(&conn_id).copied() != Some(writer_id) {
+            if binding.writer_for_conn.get(&conn_id).copied() != Some(writer_id) {
                 continue;
             }
-            inner.writer_for_conn.remove(&conn_id);
-            if let Some(m) = inner.meta.get(&conn_id) {
+            binding.writer_for_conn.remove(&conn_id);
+            if let Some(m) = binding.meta.get(&conn_id) {
                 out.push(BoundConn {
                     conn_id,
                     meta: m.clone(),
@@ -426,13 +466,13 @@ impl ConnRegistry {
 
     #[allow(dead_code)]
     pub async fn get_meta(&self, conn_id: u64) -> Option<ConnMeta> {
-        let inner = self.inner.read().await;
-        inner.meta.get(&conn_id).cloned()
+        let binding = self.binding.inner.lock().await;
+        binding.meta.get(&conn_id).cloned()
     }
 
     pub async fn is_writer_empty(&self, writer_id: u64) -> bool {
-        let inner = self.inner.read().await;
-        inner
+        let binding = self.binding.inner.lock().await;
+        binding
             .conns_for_writer
             .get(&writer_id)
             .map(|s| s.is_empty())
@@ -441,8 +481,8 @@ impl ConnRegistry {
 
     #[allow(dead_code)]
     pub async fn unregister_writer_if_empty(&self, writer_id: u64) -> bool {
-        let mut inner = self.inner.write().await;
-        let Some(conn_ids) = inner.conns_for_writer.get(&writer_id) else {
+        let mut binding = self.binding.inner.lock().await;
+        let Some(conn_ids) = binding.conns_for_writer.get(&writer_id) else {
             // Writer is already absent from the registry.
             return true;
         };
@@ -450,19 +490,19 @@ impl ConnRegistry {
             return false;
         }
 
-        inner.writers.remove(&writer_id);
-        inner.last_meta_for_writer.remove(&writer_id);
-        inner.writer_idle_since_epoch_secs.remove(&writer_id);
-        inner.conns_for_writer.remove(&writer_id);
+        binding.writers.remove(&writer_id);
+        binding.last_meta_for_writer.remove(&writer_id);
+        binding.writer_idle_since_epoch_secs.remove(&writer_id);
+        binding.conns_for_writer.remove(&writer_id);
         true
     }
 
     #[allow(dead_code)]
     pub(super) async fn non_empty_writer_ids(&self, writer_ids: &[u64]) -> HashSet<u64> {
-        let inner = self.inner.read().await;
+        let binding = self.binding.inner.lock().await;
         let mut out = HashSet::<u64>::with_capacity(writer_ids.len());
         for writer_id in writer_ids {
-            if let Some(conns) = inner.conns_for_writer.get(writer_id)
+            if let Some(conns) = binding.conns_for_writer.get(writer_id)
                 && !conns.is_empty()
             {
                 out.insert(*writer_id);

src/transport/middle_proxy/send.rs

@@ -26,6 +26,9 @@ use rand::seq::SliceRandom;
 const IDLE_WRITER_PENALTY_MID_SECS: u64 = 45;
 const IDLE_WRITER_PENALTY_HIGH_SECS: u64 = 55;
 const HYBRID_GLOBAL_BURST_PERIOD_ROUNDS: u32 = 4;
+const HYBRID_RECENT_SUCCESS_WINDOW_MS: u64 = 120_000;
+const HYBRID_TIMEOUT_WARN_RATE_LIMIT_MS: u64 = 5_000;
+const HYBRID_RECOVERY_TRIGGER_MIN_INTERVAL_MS: u64 = 5_000;
 const PICK_PENALTY_WARM: u64 = 200;
 const PICK_PENALTY_DRAINING: u64 = 600;
 const PICK_PENALTY_STALE: u64 = 300;
@@ -68,8 +71,11 @@ impl MePool {
                 },
             )
         };
-        let no_writer_mode =
-            MeRouteNoWriterMode::from_u8(self.me_route_no_writer_mode.load(Ordering::Relaxed));
+        let no_writer_mode = MeRouteNoWriterMode::from_u8(
+            self.route_runtime
+                .me_route_no_writer_mode
+                .load(Ordering::Relaxed),
+        );
         let (routed_dc, unknown_target_dc) =
             self.resolve_target_dc_for_routing(target_dc as i32).await;
         let mut no_writer_deadline: Option<Instant> = None;
@@ -77,7 +83,11 @@ impl MePool {
         let mut async_recovery_triggered = false;
         let mut hybrid_recovery_round = 0u32;
         let mut hybrid_last_recovery_at: Option<Instant> = None;
-        let hybrid_wait_step = self.me_route_no_writer_wait.max(Duration::from_millis(50));
+        let mut hybrid_total_deadline: Option<Instant> = None;
+        let hybrid_wait_step = self
+            .route_runtime
+            .me_route_no_writer_wait
+            .max(Duration::from_millis(50));
         let mut hybrid_wait_current = hybrid_wait_step;
 
         loop {
@@ -92,9 +102,13 @@ impl MePool {
                     .tx
                     .try_send(WriterCommand::Data(current_payload.clone()))
                 {
-                    Ok(()) => return Ok(()),
+                    Ok(()) => {
+                        self.note_hybrid_route_success();
+                        return Ok(());
+                    }
                     Err(TrySendError::Full(cmd)) => {
                         if current.tx.send(cmd).await.is_ok() {
+                            self.note_hybrid_route_success();
                             return Ok(());
                         }
                         warn!(writer_id = current.writer_id, "ME writer channel closed");
@@ -118,7 +132,7 @@ impl MePool {
                     match no_writer_mode {
                         MeRouteNoWriterMode::AsyncRecoveryFailfast => {
                             let deadline = *no_writer_deadline.get_or_insert_with(|| {
-                                Instant::now() + self.me_route_no_writer_wait
+                                Instant::now() + self.route_runtime.me_route_no_writer_wait
                             });
                             if !async_recovery_triggered && !unknown_target_dc {
                                 let triggered =
@@ -139,7 +153,9 @@ impl MePool {
                         MeRouteNoWriterMode::InlineRecoveryLegacy => {
                             self.stats.increment_me_inline_recovery_total();
                             if !unknown_target_dc {
-                                for _ in 0..self.me_route_inline_recovery_attempts.max(1) {
+                                for _ in
+                                    0..self.route_runtime.me_route_inline_recovery_attempts.max(1)
+                                {
                                     for family in self.family_order() {
                                         let map = match family {
                                             IpFamily::V4 => self.proxy_map_v4.read().await.clone(),
@@ -168,7 +184,7 @@ impl MePool {
                                 continue;
                             }
                             let deadline = *no_writer_deadline.get_or_insert_with(|| {
-                                Instant::now() + self.me_route_inline_recovery_wait
+                                Instant::now() + self.route_runtime.me_route_inline_recovery_wait
                             });
                             if !self.wait_for_writer_until(deadline).await {
                                 if !self.writers.read().await.is_empty() {
@@ -182,6 +198,15 @@ impl MePool {
                             continue;
                         }
                         MeRouteNoWriterMode::HybridAsyncPersistent => {
+                            let total_deadline = *hybrid_total_deadline.get_or_insert_with(|| {
+                                Instant::now() + self.hybrid_total_wait_budget()
+                            });
+                            if Instant::now() >= total_deadline {
+                                self.on_hybrid_timeout(total_deadline, routed_dc);
+                                return Err(ProxyError::Proxy(
+                                    "ME writer not available within hybrid timeout".into(),
+                                ));
+                            }
                             if !unknown_target_dc {
                                 self.maybe_trigger_hybrid_recovery(
                                     routed_dc,
@@ -214,8 +239,9 @@ impl MePool {
                 let pick_mode = self.writer_pick_mode();
                 match no_writer_mode {
                     MeRouteNoWriterMode::AsyncRecoveryFailfast => {
-                        let deadline = *no_writer_deadline
-                            .get_or_insert_with(|| Instant::now() + self.me_route_no_writer_wait);
+                        let deadline = *no_writer_deadline.get_or_insert_with(|| {
+                            Instant::now() + self.route_runtime.me_route_no_writer_wait
+                        });
                         if !async_recovery_triggered && !unknown_target_dc {
                             let triggered =
                                 self.trigger_async_recovery_for_target_dc(routed_dc).await;
@@ -238,7 +264,7 @@ impl MePool {
                         self.stats.increment_me_inline_recovery_total();
                         if unknown_target_dc {
                             let deadline = *no_writer_deadline.get_or_insert_with(|| {
-                                Instant::now() + self.me_route_inline_recovery_wait
+                                Instant::now() + self.route_runtime.me_route_inline_recovery_wait
                             });
                             if self.wait_for_candidate_until(routed_dc, deadline).await {
                                 continue;
@@ -250,7 +276,9 @@ impl MePool {
                                 "No ME writers available for target DC".into(),
                             ));
                         }
-                        if emergency_attempts >= self.me_route_inline_recovery_attempts.max(1) {
+                        if emergency_attempts
+                            >= self.route_runtime.me_route_inline_recovery_attempts.max(1)
+                        {
                             self.stats
                                 .increment_me_writer_pick_no_candidate_total(pick_mode);
                             self.stats.increment_me_no_writer_failfast_total();
@@ -292,6 +320,16 @@ impl MePool {
                         }
                     }
                     MeRouteNoWriterMode::HybridAsyncPersistent => {
+                        let total_deadline = *hybrid_total_deadline.get_or_insert_with(|| {
+                            Instant::now() + self.hybrid_total_wait_budget()
+                        });
+                        if Instant::now() >= total_deadline {
+                            self.on_hybrid_timeout(total_deadline, routed_dc);
+                            return Err(ProxyError::Proxy(
+                                "No ME writers available for target DC within hybrid timeout"
+                                    .into(),
+                            ));
+                        }
                         if !unknown_target_dc {
                             self.maybe_trigger_hybrid_recovery(
                                 routed_dc,
@@ -332,7 +370,11 @@ impl MePool {
                     pick_sample_size,
                 )
             } else {
-                if self.me_deterministic_writer_sort.load(Ordering::Relaxed) {
+                if self
+                    .writer_selection_policy
+                    .me_deterministic_writer_sort
+                    .load(Ordering::Relaxed)
+                {
                     candidate_indices.sort_by(|lhs, rhs| {
                         let left = &writers_snapshot[*lhs];
                         let right = &writers_snapshot[*rhs];
@@ -423,6 +465,7 @@ impl MePool {
                                 "Selected stale ME writer for fallback bind"
                             );
                         }
+                        self.note_hybrid_route_success();
                         return Ok(());
                     }
                     Err(TrySendError::Full(_)) => {
@@ -453,7 +496,19 @@ impl MePool {
                 .increment_me_writer_pick_blocking_fallback_total();
             let effective_our_addr = SocketAddr::new(w.source_ip, our_addr.port());
             let (payload, meta) = build_routed_payload(effective_our_addr);
-            match w.tx.clone().reserve_owned().await {
+            let reserve_result =
+                if let Some(timeout) = self.route_runtime.me_route_blocking_send_timeout {
+                    match tokio::time::timeout(timeout, w.tx.clone().reserve_owned()).await {
+                        Ok(result) => result,
+                        Err(_) => {
+                            self.stats.increment_me_writer_pick_full_total(pick_mode);
+                            continue;
+                        }
+                    }
+                } else {
+                    w.tx.clone().reserve_owned().await
+                };
+            match reserve_result {
                 Ok(permit) => {
                     if !self.registry.bind_writer(conn_id, w.id, meta).await {
                         debug!(
@@ -471,6 +526,7 @@ impl MePool {
                     if w.generation < self.current_generation() {
                         self.stats.increment_pool_stale_pick_total();
                     }
+                    self.note_hybrid_route_success();
                     return Ok(());
                 }
                 Err(_) => {
@@ -483,7 +539,7 @@ impl MePool {
     }
 
     async fn wait_for_writer_until(&self, deadline: Instant) -> bool {
-        let waiter = self.writer_available.notified();
+        let mut rx = self.writer_epoch.subscribe();
         if !self.writers.read().await.is_empty() {
             return true;
         }
@@ -492,13 +548,14 @@ impl MePool {
             return !self.writers.read().await.is_empty();
         }
         let timeout = deadline.saturating_duration_since(now);
-        if tokio::time::timeout(timeout, waiter).await.is_ok() {
-            return true;
+        if tokio::time::timeout(timeout, rx.changed()).await.is_ok() {
+            return !self.writers.read().await.is_empty();
         }
         !self.writers.read().await.is_empty()
     }
 
     async fn wait_for_candidate_until(&self, routed_dc: i32, deadline: Instant) -> bool {
+        let mut rx = self.writer_epoch.subscribe();
         loop {
             if self.has_candidate_for_target_dc(routed_dc).await {
                 return true;
@@ -509,7 +566,6 @@ impl MePool {
                 return self.has_candidate_for_target_dc(routed_dc).await;
             }
 
-            let waiter = self.writer_available.notified();
             if self.has_candidate_for_target_dc(routed_dc).await {
                 return true;
             }
@@ -517,7 +573,7 @@ impl MePool {
             if remaining.is_zero() {
                 return self.has_candidate_for_target_dc(routed_dc).await;
             }
-            if tokio::time::timeout(remaining, waiter).await.is_err() {
+            if tokio::time::timeout(remaining, rx.changed()).await.is_err() {
                 return self.has_candidate_for_target_dc(routed_dc).await;
             }
         }
@@ -587,6 +643,9 @@ impl MePool {
         hybrid_last_recovery_at: &mut Option<Instant>,
         hybrid_wait_step: Duration,
     ) {
+        if !self.try_consume_hybrid_recovery_trigger_slot(HYBRID_RECOVERY_TRIGGER_MIN_INTERVAL_MS) {
+            return;
+        }
         if let Some(last) = *hybrid_last_recovery_at
             && last.elapsed() < hybrid_wait_step
         {
@@ -602,6 +661,78 @@ impl MePool {
         *hybrid_last_recovery_at = Some(Instant::now());
     }
 
+    fn hybrid_total_wait_budget(&self) -> Duration {
+        let base = self
+            .route_runtime
+            .me_route_hybrid_max_wait
+            .max(Duration::from_millis(50));
+        let now_ms = Self::now_epoch_millis();
+        let last_success_ms = self
+            .route_runtime
+            .me_route_last_success_epoch_ms
+            .load(Ordering::Relaxed);
+        if last_success_ms != 0
+            && now_ms.saturating_sub(last_success_ms) <= HYBRID_RECENT_SUCCESS_WINDOW_MS
+        {
+            return base.saturating_mul(2);
+        }
+        base
+    }
+
+    fn note_hybrid_route_success(&self) {
+        self.route_runtime
+            .me_route_last_success_epoch_ms
+            .store(Self::now_epoch_millis(), Ordering::Relaxed);
+    }
+
+    fn on_hybrid_timeout(&self, deadline: Instant, routed_dc: i32) {
+        self.stats.increment_me_hybrid_timeout_total();
+        let now_ms = Self::now_epoch_millis();
+        let mut last_warn_ms = self
+            .route_runtime
+            .me_route_hybrid_timeout_warn_epoch_ms
+            .load(Ordering::Relaxed);
+        while now_ms.saturating_sub(last_warn_ms) >= HYBRID_TIMEOUT_WARN_RATE_LIMIT_MS {
+            match self
+                .route_runtime
+                .me_route_hybrid_timeout_warn_epoch_ms
+                .compare_exchange_weak(last_warn_ms, now_ms, Ordering::AcqRel, Ordering::Relaxed)
+            {
+                Ok(_) => {
+                    warn!(
+                        routed_dc,
+                        budget_ms = self.hybrid_total_wait_budget().as_millis() as u64,
+                        elapsed_ms = deadline.elapsed().as_millis() as u64,
+                        "ME hybrid route timeout reached"
+                    );
+                    break;
+                }
+                Err(actual) => last_warn_ms = actual,
+            }
+        }
+    }
+
+    fn try_consume_hybrid_recovery_trigger_slot(&self, min_interval_ms: u64) -> bool {
+        let now_ms = Self::now_epoch_millis();
+        let mut last_trigger_ms = self
+            .route_runtime
+            .me_async_recovery_last_trigger_epoch_ms
+            .load(Ordering::Relaxed);
+        loop {
+            if now_ms.saturating_sub(last_trigger_ms) < min_interval_ms {
+                return false;
+            }
+            match self
+                .route_runtime
+                .me_async_recovery_last_trigger_epoch_ms
+                .compare_exchange_weak(last_trigger_ms, now_ms, Ordering::AcqRel, Ordering::Relaxed)
+            {
+                Ok(_) => return true,
+                Err(actual) => last_trigger_ms = actual,
+            }
+        }
+    }
+
     pub async fn send_close(self: &Arc<Self>, conn_id: u64) -> Result<()> {
         if let Some(w) = self.registry.get_writer(conn_id).await {
             let mut p = Vec::with_capacity(12);
@@ -749,7 +880,7 @@ impl MePool {
             (self.writer_idle_rank_for_selection(writer, idle_since_by_writer, now_epoch_secs)
                 as u64)
                 * 100;
-        let queue_cap = self.writer_cmd_channel_capacity.max(1) as u64;
+        let queue_cap = self.writer_lifecycle.writer_cmd_channel_capacity.max(1) as u64;
         let queue_remaining = writer.tx.capacity() as u64;
         let queue_used = queue_cap.saturating_sub(queue_remaining.min(queue_cap));
         let queue_util_pct = queue_used.saturating_mul(100) / queue_cap;

src/transport/middle_proxy/tests/health_adversarial_tests.rs

@@ -113,6 +113,8 @@ async fn make_pool(
         general.me_warn_rate_limit_ms,
         MeRouteNoWriterMode::default(),
         general.me_route_no_writer_wait_ms,
+        general.me_route_hybrid_max_wait_ms,
+        general.me_route_blocking_send_timeout_ms,
         general.me_route_inline_recovery_attempts,
         general.me_route_inline_recovery_wait_ms,
     );

src/transport/middle_proxy/tests/health_integration_tests.rs

@@ -111,6 +111,8 @@ async fn make_pool(
         general.me_warn_rate_limit_ms,
         MeRouteNoWriterMode::default(),
         general.me_route_no_writer_wait_ms,
+        general.me_route_hybrid_max_wait_ms,
+        general.me_route_blocking_send_timeout_ms,
         general.me_route_inline_recovery_attempts,
         general.me_route_inline_recovery_wait_ms,
     );

src/transport/middle_proxy/tests/health_regression_tests.rs

@@ -106,6 +106,8 @@ async fn make_pool(me_pool_drain_threshold: u64) -> Arc<MePool> {
         general.me_warn_rate_limit_ms,
         MeRouteNoWriterMode::default(),
         general.me_route_no_writer_wait_ms,
+        general.me_route_hybrid_max_wait_ms,
+        general.me_route_blocking_send_timeout_ms,
         general.me_route_inline_recovery_attempts,
         general.me_route_inline_recovery_wait_ms,
     )

src/transport/middle_proxy/tests/pool_refill_security_tests.rs

@@ -95,6 +95,8 @@ async fn make_pool() -> Arc<MePool> {
         general.me_warn_rate_limit_ms,
         MeRouteNoWriterMode::default(),
         general.me_route_no_writer_wait_ms,
+        general.me_route_hybrid_max_wait_ms,
+        general.me_route_blocking_send_timeout_ms,
         general.me_route_inline_recovery_attempts,
         general.me_route_inline_recovery_wait_ms,
     )

src/transport/middle_proxy/tests/pool_writer_security_tests.rs

@@ -35,7 +35,7 @@ async fn make_pool() -> Arc<MePool> {
         NetworkDecision::default(),
         None,
         Arc::new(SecureRandom::new()),
-        Arc::new(Stats::default()),
+        Arc::new(Stats::new()),
         general.me_keepalive_enabled,
         general.me_keepalive_interval_secs,
         general.me_keepalive_jitter_secs,
@@ -100,6 +100,8 @@ async fn make_pool() -> Arc<MePool> {
         general.me_warn_rate_limit_ms,
         MeRouteNoWriterMode::default(),
         general.me_route_no_writer_wait_ms,
+        general.me_route_hybrid_max_wait_ms,
+        general.me_route_blocking_send_timeout_ms,
         general.me_route_inline_recovery_attempts,
         general.me_route_inline_recovery_wait_ms,
     )
@@ -171,10 +173,15 @@ async fn bind_conn_to_writer(pool: &Arc<MePool>, writer_id: u64, port: u16) -> u
 }
 
 #[tokio::test]
-async fn remove_draining_writer_still_quarantines_flapping_endpoint() {
+async fn remove_draining_writer_does_not_quarantine_flapping_endpoint() {
     let pool = make_pool().await;
     let writer_id = 77;
     let addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 12, 0, 77)), 443);
+    let before_total = pool.stats.get_me_endpoint_quarantine_total();
+    let before_unexpected = pool.stats.get_me_endpoint_quarantine_unexpected_total();
+    let before_suppressed = pool
+        .stats
+        .get_me_endpoint_quarantine_draining_suppressed_total();
     insert_writer(
         &pool,
         writer_id,
@@ -198,8 +205,18 @@ async fn remove_draining_writer_still_quarantines_flapping_endpoint() {
         "writer must be removed from pool after cleanup"
     );
     assert!(
-        pool.is_endpoint_quarantined(addr).await,
-        "draining removals must still quarantine flapping endpoints"
+        !pool.is_endpoint_quarantined(addr).await,
+        "draining removals must not quarantine endpoint"
+    );
+    assert_eq!(pool.stats.get_me_endpoint_quarantine_total(), before_total);
+    assert_eq!(
+        pool.stats.get_me_endpoint_quarantine_unexpected_total(),
+        before_unexpected
+    );
+    assert_eq!(
+        pool.stats
+            .get_me_endpoint_quarantine_draining_suppressed_total(),
+        before_suppressed + 1
     );
     assert_eq!(pool.conn_count.load(Ordering::Relaxed), 0);
 }
@@ -255,16 +272,21 @@ async fn edge_draining_only_detach_rejects_active_writer() {
 }
 
 #[tokio::test]
-async fn adversarial_blackhat_single_remove_establishes_single_quarantine_entry() {
+async fn adversarial_blackhat_single_unexpected_remove_establishes_single_quarantine_entry() {
     let pool = make_pool().await;
     let writer_id = 93;
     let addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 12, 0, 93)), 443);
+    let before_total = pool.stats.get_me_endpoint_quarantine_total();
+    let before_unexpected = pool.stats.get_me_endpoint_quarantine_unexpected_total();
+    let before_suppressed = pool
+        .stats
+        .get_me_endpoint_quarantine_draining_suppressed_total();
     insert_writer(
         &pool,
         writer_id,
         2,
         addr,
-        true,
+        false,
         Instant::now() - Duration::from_secs(1),
     )
     .await;
@@ -272,6 +294,49 @@ async fn adversarial_blackhat_single_remove_establishes_single_quarantine_entry(
     pool.remove_writer_and_close_clients(writer_id).await;
     assert!(pool.is_endpoint_quarantined(addr).await);
     assert_eq!(pool.endpoint_quarantine.lock().await.len(), 1);
+    assert_eq!(
+        pool.stats.get_me_endpoint_quarantine_total(),
+        before_total + 1
+    );
+    assert_eq!(
+        pool.stats.get_me_endpoint_quarantine_unexpected_total(),
+        before_unexpected + 1
+    );
+    assert_eq!(
+        pool.stats
+            .get_me_endpoint_quarantine_draining_suppressed_total(),
+        before_suppressed
+    );
+}
+
+#[tokio::test]
+async fn remove_ultra_short_uptime_writer_skips_flap_quarantine() {
+    let pool = make_pool().await;
+    let writer_id = 931;
+    let addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 12, 0, 131)), 443);
+    let before_total = pool.stats.get_me_endpoint_quarantine_total();
+    let before_unexpected = pool.stats.get_me_endpoint_quarantine_unexpected_total();
+    insert_writer(
+        &pool,
+        writer_id,
+        2,
+        addr,
+        false,
+        Instant::now() - Duration::from_millis(50),
+    )
+    .await;
+
+    pool.remove_writer_and_close_clients(writer_id).await;
+
+    assert!(
+        !pool.is_endpoint_quarantined(addr).await,
+        "ultra-short unexpected lifetime must not quarantine endpoint"
+    );
+    assert_eq!(pool.stats.get_me_endpoint_quarantine_total(), before_total);
+    assert_eq!(
+        pool.stats.get_me_endpoint_quarantine_unexpected_total(),
+        before_unexpected + 1
+    );
 }
 
 #[tokio::test]

src/transport/middle_proxy/tests/send_adversarial_tests.rs

@@ -106,6 +106,8 @@ async fn make_pool() -> (Arc<MePool>, Arc<SecureRandom>) {
         general.me_warn_rate_limit_ms,
         general.me_route_no_writer_mode,
         general.me_route_no_writer_wait_ms,
+        general.me_route_hybrid_max_wait_ms,
+        general.me_route_blocking_send_timeout_ms,
         general.me_route_inline_recovery_attempts,
         general.me_route_inline_recovery_wait_ms,
     );

src/transport/upstream.rs

@@ -34,8 +34,6 @@ const NUM_DCS: usize = 5;
 
 /// Timeout for individual DC ping attempt
 const DC_PING_TIMEOUT_SECS: u64 = 5;
-/// Timeout for direct TG DC TCP connect readiness.
-const DIRECT_CONNECT_TIMEOUT_SECS: u64 = 10;
 /// Interval between upstream health-check cycles.
 const HEALTH_CHECK_INTERVAL_SECS: u64 = 30;
 /// Timeout for a single health-check connect attempt.
@@ -319,6 +317,8 @@ pub struct UpstreamManager {
     connect_retry_attempts: u32,
     connect_retry_backoff: Duration,
     connect_budget: Duration,
+    /// Per-attempt TCP connect timeout to Telegram DC (`[timeouts] tg_connect`, seconds).
+    tg_connect_timeout_secs: u64,
     unhealthy_fail_threshold: u32,
     connect_failfast_hard_errors: bool,
     no_upstreams_warn_epoch_ms: Arc<AtomicU64>,
@@ -332,6 +332,7 @@ impl UpstreamManager {
         connect_retry_attempts: u32,
         connect_retry_backoff_ms: u64,
         connect_budget_ms: u64,
+        tg_connect_timeout_secs: u64,
         unhealthy_fail_threshold: u32,
         connect_failfast_hard_errors: bool,
         stats: Arc<Stats>,
@@ -347,6 +348,7 @@ impl UpstreamManager {
             connect_retry_attempts: connect_retry_attempts.max(1),
             connect_retry_backoff: Duration::from_millis(connect_retry_backoff_ms),
             connect_budget: Duration::from_millis(connect_budget_ms.max(1)),
+            tg_connect_timeout_secs: tg_connect_timeout_secs.max(1),
             unhealthy_fail_threshold: unhealthy_fail_threshold.max(1),
             connect_failfast_hard_errors,
             no_upstreams_warn_epoch_ms: Arc::new(AtomicU64::new(0)),
@@ -797,8 +799,8 @@ impl UpstreamManager {
                 break;
             }
             let remaining_budget = self.connect_budget.saturating_sub(elapsed);
-            let attempt_timeout =
-                Duration::from_secs(DIRECT_CONNECT_TIMEOUT_SECS).min(remaining_budget);
+            let attempt_timeout = Duration::from_secs(self.tg_connect_timeout_secs)
+                .min(remaining_budget);
             if attempt_timeout.is_zero() {
                 last_error = Some(ProxyError::ConnectionTimeout {
                     addr: target.to_string(),
@@ -1901,6 +1903,7 @@ mod tests {
             1,
             100,
             1000,
+            10,
             1,
             false,
             Arc::new(Stats::new()),