Merge pull request #907 from telemt/flow-carriers

Bounded Debugging + Websocket Carriers + Carriers Negotiation

Cargo.lock

@@ -2900,7 +2900,7 @@ checksum = "7b2093cf4c8eb1e67749a6762251bc9cd836b6fc171623bd0a9d324d37af2417"
 
 [[package]]
 name = "telemt"
-version = "3.5.3"
+version = "3.5.4"
 dependencies = [
  "aes",
  "anyhow",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "telemt"
-version = "3.5.3"
+version = "3.5.4"
 edition = "2024"
 
 [features]

src/api/web_status.rs

@@ -18,7 +18,7 @@ mod details;
 // Query parsing and matching remain independent from bounded HTML rendering.
 mod query;
 
-use details::{push_body, push_frames, push_headers};
+use details::{push_body, push_frames, push_headers, push_lifecycle};
 use query::{GroupBy, StatusQuery, client_ip, parse_query, record_matches};
 
 struct GroupSummary {
@@ -56,11 +56,11 @@ pub(super) async fn render(
         );
     };
     let now_millis = crate::web::trace::store_epoch_millis();
-    let since_millis = query
-        .record
-        .is_none()
-        .then(|| now_millis.saturating_sub(query.window_secs.saturating_mul(1000)))
-        .unwrap_or(0);
+    let since_millis = if query.record.is_none() {
+        now_millis.saturating_sub(query.window_secs.saturating_mul(1000))
+    } else {
+        0
+    };
     let records = store.snapshot_matching(|record| record_matches(record, &query, since_millis));
     let status = store.status();
     let mut html = String::with_capacity(MAX_PAGE_BYTES);
@@ -367,20 +367,7 @@ fn push_record(html: &mut String, record: &TraceRecord) {
             push_body(html, "message body", message.body.as_ref());
             push_frames(html, &message.frames);
         }
-        TraceRecordKind::Lifecycle(event) => {
-            html.push_str("<pre>event: ");
-            html.push_str(event.event.as_str());
-            html.push_str("\nstream: ");
-            html.push_str(
-                &event
-                    .stream_id
-                    .map(|v| v.to_string())
-                    .unwrap_or_else(|| "-".to_string()),
-            );
-            html.push_str("\nreason: ");
-            html.push_str(event.reason.unwrap_or("-"));
-            html.push_str("</pre>");
-        }
+        TraceRecordKind::Lifecycle(event) => push_lifecycle(html, event),
     }
     html.push_str("</details></td></tr>");
 }

src/api/web_status/details.rs

@@ -84,3 +84,34 @@ pub(super) fn push_body(
     }
     html.push_str("</pre>");
 }
+
+pub(super) fn push_lifecycle(html: &mut String, event: &crate::web::trace::TraceLifecycleRecord) {
+    html.push_str("<pre>event: ");
+    html.push_str(event.event.as_str());
+    html.push_str("\nstream: ");
+    html.push_str(
+        &event
+            .stream_id
+            .map(|value| value.to_string())
+            .unwrap_or_else(|| "-".to_string()),
+    );
+    html.push_str("\nreason: ");
+    html.push_str(event.reason.unwrap_or("-"));
+    if let Some(carrier) = &event.carrier {
+        html.push_str("\nclient class: ");
+        html.push_str(carrier.client_class);
+        html.push_str("\ncarrier: ");
+        html.push_str(carrier.carrier.as_str());
+        html.push_str("\nattempt: ");
+        html.push_str(&carrier.attempt.to_string());
+        html.push_str("\nscores: https=");
+        html.push_str(&carrier.scores[0].to_string());
+        html.push_str(" https-lanes=");
+        html.push_str(&carrier.scores[1].to_string());
+        html.push_str(" websocket=");
+        html.push_str(&carrier.scores[2].to_string());
+        html.push_str(" websocket-lanes=");
+        html.push_str(&carrier.scores[3].to_string());
+    }
+    html.push_str("</pre>");
+}

src/api/web_status/tests.rs

@@ -20,11 +20,15 @@ fn html_escaping_covers_active_markup_characters() {
 
 #[tokio::test]
 async fn renderer_filters_groups_and_sets_control_plane_security_headers() {
-    let mut policy = WebDebugConfig::default();
-    policy.enabled = true;
-    let mut limits = crate::config::WebLimitsConfig::default();
-    limits.debug_records_capacity = 8;
-    limits.debug_bytes_global = 16 * 1024;
+    let policy = WebDebugConfig {
+        enabled: true,
+        ..Default::default()
+    };
+    let limits = crate::config::WebLimitsConfig {
+        debug_records_capacity: 8,
+        debug_bytes_global: 16 * 1024,
+        ..Default::default()
+    };
     let store = WebTraceStore::new(policy.clone(), &limits);
     store.record_lifecycle(
         None,
@@ -79,7 +83,7 @@ async fn render_permits_remain_owned_by_inflight_response_bodies() {
 
 #[test]
 fn page_truncation_preserves_utf8_boundary_and_cap() {
-    let mut html = "я".repeat(MAX_PAGE_BYTES);
+    let mut html = "\u{044f}".repeat(MAX_PAGE_BYTES);
     truncate_page(&mut html);
     assert!(html.len() <= MAX_PAGE_BYTES);
     assert!(html.ends_with("[page output truncated]"));

src/config/hot_reload.rs

@@ -16,6 +16,7 @@
 //! | `general` | `telemetry` / `me_*_policy`    | Applied immediately                            |
 //! | `network` | `dns_overrides`                | Applied immediately                            |
 //! | `access`  | All user/quota fields          | Effective immediately                          |
+//! | `web`     | Carrier, timing, and debug policy | Applied to newly issued sessions             |
 //! Fields that require re-binding sockets (`server.listeners`, legacy
 //! `server.port`, `censorship.*`, `network.*`, `use_middle_proxy`) are **not**
 //! applied; a warning is emitted. SYN limiter rules are process-owned and are

src/config/hot_reload/tests.rs

@@ -30,6 +30,23 @@ fn write_reload_config(path: &Path, ad_tag: Option<&str>, server_port: Option<u1
     std::fs::write(path, config).unwrap();
 }
 
+fn write_web_reload_config(path: &Path, carriers: &str, carrier_learning: bool) {
+    let config = format!(
+        r#"
+                [censorship]
+                tls_domain = "example.com"
+
+                [access.users]
+                user = "00000000000000000000000000000000"
+
+                [web]
+                carriers = {carriers}
+                carrier_learning = {carrier_learning}
+            "#,
+    );
+    std::fs::write(path, config).unwrap();
+}
+
 fn temp_config_path(prefix: &str) -> PathBuf {
     let nonce = std::time::SystemTime::now()
         .duration_since(std::time::UNIX_EPOCH)
@@ -264,6 +281,29 @@ fn reload_keeps_hot_apply_when_non_hot_fields_change() {
     let _ = std::fs::remove_file(path);
 }
 
+#[test]
+fn reload_publishes_web_negotiation_policy_outside_hot_field_reporting() {
+    let path = temp_config_path("telemt_web_negotiation_reload");
+
+    write_web_reload_config(&path, "false", true);
+    let initial_cfg = Arc::new(ProxyConfig::load(&path).unwrap());
+    let initial_hash = ProxyConfig::load_with_metadata(&path)
+        .unwrap()
+        .rendered_hash;
+    let (config_tx, _config_rx) = watch::channel(initial_cfg.clone());
+    let (log_tx, _log_rx) = watch::channel(initial_cfg.general.log_level.clone());
+    let mut reload_state = ReloadState::new(Some(initial_hash));
+
+    write_web_reload_config(&path, "[\"websocket\", \"https\"]", false);
+    reload_config(&path, &config_tx, &log_tx, None, None, &mut reload_state).unwrap();
+
+    let applied = config_tx.borrow().clone();
+    assert!(applied.web.carrier_negotiation_enabled());
+    assert!(!applied.web.carrier_learning);
+
+    let _ = std::fs::remove_file(path);
+}
+
 #[test]
 fn classify_sni_change_requires_restart() {
     // censorship.* is not in overlay_hot_fields -> restart.

src/config/hot_reload/watcher.rs

@@ -164,7 +164,7 @@ pub(super) fn reload_config(
     let old_hot = HotFields::from_config(&old_cfg);
     let applied_hot = HotFields::from_config(&applied_cfg);
     let non_hot_changed = !config_equal(&applied_cfg, &new_cfg);
-    let hot_changed = old_hot != applied_hot;
+    let hot_changed = !config_equal(&old_cfg, &applied_cfg);
 
     if non_hot_changed {
         warn_non_hot_changes(&old_cfg, &new_cfg, non_hot_changed);

src/config/load/runtime_web.rs

@@ -27,6 +27,7 @@ pub(super) fn rebuild(config: &mut ProxyConfig) -> Result<()> {
     let mut static_files = 0usize;
     let mut static_bytes = 0usize;
 
+    let carrier_candidates: Arc<[WebCarrier]> = config.web.carrier_candidates().into();
     for vhost in &config.web.vhosts {
         let decoy = build_decoy(
             vhost,
@@ -63,6 +64,14 @@ pub(super) fn rebuild(config: &mut ProxyConfig) -> Result<()> {
                 user: profile.user.clone(),
                 secret_mode: profile.secret_mode,
                 carrier: config.web.carrier,
+                carrier_negotiation_enabled: config.web.carrier_negotiation_enabled(),
+                carrier_learning: config.web.carrier_negotiation_enabled()
+                    && config.web.carrier_learning,
+                carriers: Arc::clone(&carrier_candidates),
+                carrier_negotiation_deadlines_secs: config
+                    .web
+                    .timeouts
+                    .carrier_negotiation_deadlines_secs,
                 capability,
                 key_fingerprint,
                 max_sessions: profile

src/config/load/strict_keys.rs

@@ -260,7 +260,15 @@ const LISTENER_CONFIG_KEYS: &[&str] = &[
 ];
 
 const WEB_CONFIG_KEYS: &[&str] = &[
-    "enabled", "carrier", "debug", "limits", "timeouts", "vhosts",
+    "enabled",
+    "carrier",
+    "carriers",
+    "carrier_learning",
+    "carrier_negotiation_aggressiveness",
+    "debug",
+    "limits",
+    "timeouts",
+    "vhosts",
 ];
 
 const WEB_LIMITS_CONFIG_KEYS: &[&str] = &[
@@ -271,10 +279,15 @@ const WEB_LIMITS_CONFIG_KEYS: &[&str] = &[
     "max_frames_per_body",
     "max_http_connections",
     "max_http_handlers",
+    "max_lane_open_waits_per_session",
+    "pending_bytes_per_lane",
+    "pending_items_per_lane",
     "websocket_bytes_global",
     "websocket_admission_watermark_pct",
     "websocket_eviction_watermark_pct",
     "websocket_http_connection_reserve",
+    "max_websocket_evictions_in_flight",
+    "max_carrier_learning_entries",
     "max_body_readers",
     "max_body_bytes_global",
     "max_sessions_global",
@@ -324,10 +337,17 @@ const WEB_TIMEOUTS_CONFIG_KEYS: &[&str] = &[
     "header_secs",
     "body_secs",
     "stream_handshake_secs",
+    "stream_first_byte_secs",
     "long_poll_secs",
+    "lane_open_wait_secs",
+    "carrier_health_secs",
+    "websocket_upgrade_secs",
+    "websocket_open_secs",
     "websocket_write_secs",
     "websocket_backpressure_secs",
     "websocket_eviction_secs",
+    "carrier_negotiation_deadlines_secs",
+    "carrier_learning_secs",
     "bootstrap_lifetime_secs",
     "reconnect_grace_secs",
     "http_idle_secs",

src/config/load/validate_web.rs

@@ -6,6 +6,10 @@ use super::*;
 mod debug;
 // Memory-envelope arithmetic remains isolated from protocol validation.
 mod memory;
+// Carrier ordering, cumulative deadlines, and fallback identity are validated together.
+mod negotiation;
+// Request and lifecycle timeout relationships are validated together.
+mod timeouts;
 // WebSocket transport policy is validated independently from HTTP body policy.
 mod websocket;
 
@@ -67,11 +71,17 @@ pub(super) fn validate(config: &mut ProxyConfig) -> Result<()> {
 
     validate_limits(&config.web.limits)?;
     debug::validate(&config.web.debug, &config.web.limits)?;
-    if config.web.carrier == WebCarrier::HttpsLanes && config.web.limits.max_http_handlers < 2 {
-        return config_error("web.carrier=https-lanes requires web.limits.max_http_handlers >= 2");
+    let carriers = negotiation::validate(&config.web)?;
+    if carriers.contains(&WebCarrier::Https) && config.web.limits.max_http_handlers < 2 {
+        return config_error("WEB https candidates require web.limits.max_http_handlers >= 2");
     }
-    validate_timeouts(&config.web.timeouts)?;
-    websocket::validate(config.web.carrier, &config.web.limits, &config.web.timeouts)?;
+    if carriers.contains(&WebCarrier::HttpsLanes) && config.web.limits.max_http_handlers < 4 {
+        return config_error(
+            "WEB https-lanes candidates require web.limits.max_http_handlers >= 4",
+        );
+    }
+    timeouts::validate(&config.web.timeouts)?;
+    websocket::validate(&carriers, &config.web.limits, &config.web.timeouts)?;
     validate_vhosts(config)?;
     Ok(())
 }
@@ -136,6 +146,11 @@ fn validate_limits(limits: &WebLimitsConfig) -> Result<()> {
     if !(1..=MAX_WEB_TOMBSTONES_PER_SESSION).contains(&limits.max_tombstones_per_session) {
         return config_error("web.limits.max_tombstones_per_session must be within [1, 4096]");
     }
+    if limits.pending_bytes_per_lane <= WEB_FRAME_HEADER_BYTES + WEB_QUEUE_ITEM_COST {
+        return config_error(
+            "web.limits.pending_bytes_per_lane must preserve one non-empty DATA frame",
+        );
+    }
     if limits.carrier_batch_bytes > limits.max_body_bytes
         || limits.carrier_batch_bytes
             < limits
@@ -155,6 +170,20 @@ fn validate_limits(limits: &WebLimitsConfig) -> Result<()> {
     let positive = [
         ("max_http_connections", limits.max_http_connections),
         ("max_http_handlers", limits.max_http_handlers),
+        (
+            "max_lane_open_waits_per_session",
+            limits.max_lane_open_waits_per_session,
+        ),
+        ("pending_bytes_per_lane", limits.pending_bytes_per_lane),
+        ("pending_items_per_lane", limits.pending_items_per_lane),
+        (
+            "max_websocket_evictions_in_flight",
+            limits.max_websocket_evictions_in_flight,
+        ),
+        (
+            "max_carrier_learning_entries",
+            limits.max_carrier_learning_entries,
+        ),
         ("max_body_readers", limits.max_body_readers),
         ("max_body_bytes_global", limits.max_body_bytes_global),
         ("max_sessions_global", limits.max_sessions_global),
@@ -227,8 +256,11 @@ fn validate_limits(limits: &WebLimitsConfig) -> Result<()> {
         || limits.max_bootstraps_per_ip > limits.max_bootstraps_global
         || limits.max_http_handlers > limits.max_http_connections
         || limits.max_body_readers > limits.max_http_handlers
+        || limits.max_lane_open_waits_per_session > limits.max_streams_per_session
         || limits.pending_bytes_per_session > limits.pending_bytes_global
         || limits.pending_items_per_session > limits.pending_items_global
+        || limits.pending_bytes_per_lane > limits.pending_bytes_per_session
+        || limits.pending_items_per_lane > limits.pending_items_per_session
         || limits.control_bytes_per_session > limits.control_bytes_global
         || limits.control_bytes_per_session > limits.pending_bytes_per_session
         || limits.control_bytes_global > limits.pending_bytes_global
@@ -324,41 +356,6 @@ fn validate_limits(limits: &WebLimitsConfig) -> Result<()> {
     Ok(())
 }
 
-fn validate_timeouts(timeouts: &WebTimeoutsConfig) -> Result<()> {
-    let values = [
-        ("header_secs", timeouts.header_secs),
-        ("body_secs", timeouts.body_secs),
-        ("stream_handshake_secs", timeouts.stream_handshake_secs),
-        ("long_poll_secs", timeouts.long_poll_secs),
-        ("websocket_write_secs", timeouts.websocket_write_secs),
-        (
-            "websocket_backpressure_secs",
-            timeouts.websocket_backpressure_secs,
-        ),
-        ("websocket_eviction_secs", timeouts.websocket_eviction_secs),
-        ("bootstrap_lifetime_secs", timeouts.bootstrap_lifetime_secs),
-        ("reconnect_grace_secs", timeouts.reconnect_grace_secs),
-        ("http_idle_secs", timeouts.http_idle_secs),
-        ("shutdown_secs", timeouts.shutdown_secs),
-        ("decoy_header_secs", timeouts.decoy_header_secs),
-    ];
-    if let Some((field, _)) = values
-        .into_iter()
-        .find(|(_, value)| !(1..=3600).contains(value))
-    {
-        return config_error(&format!("web.timeouts.{field} must be within [1, 3600]"));
-    }
-    let request_deadline = timeouts
-        .header_secs
-        .max(timeouts.body_secs)
-        .max(timeouts.long_poll_secs)
-        .max(timeouts.decoy_header_secs);
-    if request_deadline >= timeouts.http_idle_secs {
-        return config_error("web.timeouts request deadlines must be lower than http_idle_secs");
-    }
-    Ok(())
-}
-
 fn validate_vhosts(config: &mut ProxyConfig) -> Result<()> {
     let limits = &config.web.limits;
     if config.web.vhosts.len() > limits.max_vhosts {

src/config/load/validate_web/memory.rs

@@ -3,9 +3,14 @@ use super::*;
 const WEB_DEBUG_RENDERERS: usize = 2;
 const WEB_DEBUG_STATUS_PAGE_BYTES: usize = 8 * 1024 * 1024;
 const WEB_DEBUG_GROUP_SCRATCH_BYTES: usize = 4 * 1024 * 1024;
+const WEB_CARRIER_LEARNING_ENTRY_BYTES: usize = 512;
+const WEB_LANE_STATE_BYTES: usize = 512;
 
 /// Validates process-wide body, header, queue, static, and debug reservations.
 pub(super) fn validate(limits: &WebLimitsConfig) -> Result<()> {
+    if limits.max_carrier_learning_entries == 0 {
+        return config_error("web.limits.max_carrier_learning_entries must be > 0");
+    }
     let body_reservation = limits
         .max_body_readers
         .checked_mul(limits.max_body_bytes)
@@ -47,6 +52,21 @@ pub(super) fn validate(limits: &WebLimitsConfig) -> Result<()> {
                 .and_then(|scratch| value.checked_add(scratch))
         })
         .ok_or_else(|| ProxyError::Config("web.debug reservations overflowed usize".to_string()))?;
+    let carrier_learning_reservation = limits
+        .max_carrier_learning_entries
+        .checked_mul(WEB_CARRIER_LEARNING_ENTRY_BYTES)
+        .ok_or_else(|| {
+            ProxyError::Config("web.carrier learning reservation overflowed usize".to_string())
+        })?;
+    let lane_state_reservation = limits
+        .max_streams_per_session
+        .checked_add(limits.max_tombstones_per_session)
+        .and_then(|value| value.checked_add(1))
+        .and_then(|value| value.checked_mul(limits.max_sessions_global))
+        .and_then(|value| value.checked_mul(WEB_LANE_STATE_BYTES))
+        .ok_or_else(|| {
+            ProxyError::Config("web.limits lane state reservation overflowed usize".to_string())
+        })?;
     let reserved = limits
         .pending_bytes_global
         .checked_add(limits.max_body_bytes_global)
@@ -54,6 +74,8 @@ pub(super) fn validate(limits: &WebLimitsConfig) -> Result<()> {
         .and_then(|value| value.checked_add(debug_ring_index))
         .and_then(|value| value.checked_add(status_pages))
         .and_then(|value| value.checked_add(debug_reservation))
+        .and_then(|value| value.checked_add(carrier_learning_reservation))
+        .and_then(|value| value.checked_add(lane_state_reservation))
         .and_then(|value| value.checked_add(http_header_reservation))
         .ok_or_else(|| ProxyError::Config("web.limits byte ceilings overflow usize".to_string()))?;
     if reserved > limits.memory_envelope_bytes
@@ -65,3 +87,20 @@ pub(super) fn validate(limits: &WebLimitsConfig) -> Result<()> {
     }
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn default_envelope_includes_bounded_lane_and_learning_metadata() {
+        let limits = WebLimitsConfig::default();
+        assert!(validate(&limits).is_ok());
+
+        let previous_envelope = WebLimitsConfig {
+            memory_envelope_bytes: 768 * 1024 * 1024,
+            ..limits
+        };
+        assert!(validate(&previous_envelope).is_err());
+    }
+}

src/config/load/validate_web/negotiation.rs

@@ -0,0 +1,123 @@
+use std::collections::HashSet;
+
+use super::*;
+
+/// Validates bounded carrier selection and learning policy.
+pub(super) fn validate(config: &WebConfig) -> Result<Vec<WebCarrier>> {
+    if let Some(carriers) = config.carriers.enabled() {
+        if carriers.is_empty() {
+            return config_error("web.carriers must contain at least one carrier");
+        }
+        let mut unique = HashSet::with_capacity(carriers.len());
+        if carriers.iter().any(|carrier| !unique.insert(*carrier)) {
+            return config_error("web.carriers must not contain duplicate carriers");
+        }
+    }
+    let candidates = config.carrier_candidates();
+    if config.carrier_negotiation_enabled()
+        && config.carrier_learning
+        && config.limits.max_carrier_learning_entries < 3
+    {
+        return config_error(
+            "web.limits.max_carrier_learning_entries must be >= 3 when carrier learning is enabled",
+        );
+    }
+    if candidates.len() > WebCarrier::ALL.len() {
+        return config_error(
+            "web.carriers and the web.carrier fallback must contain at most four carriers",
+        );
+    }
+    let deadlines = config.timeouts.carrier_negotiation_deadlines_secs;
+    if deadlines[0] == 0 || deadlines.windows(2).any(|pair| pair[0] >= pair[1]) {
+        return config_error(
+            "web.timeouts.carrier_negotiation_deadlines_secs must be non-zero and strictly increasing",
+        );
+    }
+    let retained_chain_secs = deadlines[3]
+        .checked_add(config.timeouts.carrier_health_secs)
+        .and_then(|value| value.checked_add(1));
+    if retained_chain_secs.is_none_or(|value| value >= config.timeouts.bootstrap_lifetime_secs) {
+        return config_error(
+            "web.timeouts final carrier deadline plus health and cleanup must be lower than bootstrap_lifetime_secs",
+        );
+    }
+    Ok(candidates)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn fallback_is_appended_once() {
+        let config = WebConfig {
+            carrier: WebCarrier::Https,
+            carriers: WebCarriers::Enabled(vec![WebCarrier::Websocket, WebCarrier::Https]),
+            ..Default::default()
+        };
+        assert_eq!(
+            validate(&config).unwrap(),
+            vec![WebCarrier::Websocket, WebCarrier::Https]
+        );
+    }
+
+    #[test]
+    fn duplicate_carriers_are_rejected() {
+        let config = WebConfig {
+            carriers: WebCarriers::Enabled(vec![WebCarrier::Websocket, WebCarrier::Websocket]),
+            ..Default::default()
+        };
+        assert!(validate(&config).is_err());
+    }
+
+    #[test]
+    fn missing_or_false_carriers_disable_negotiation() {
+        #[derive(serde::Deserialize)]
+        struct Wrapper {
+            value: WebCarriers,
+        }
+
+        let config = WebConfig::default();
+        assert!(!config.carrier_negotiation_enabled());
+        assert_eq!(validate(&config).unwrap(), [WebCarrier::Https]);
+
+        let disabled: Wrapper = toml::from_str("value = false").unwrap();
+        assert_eq!(disabled.value, WebCarriers::Disabled);
+        assert!(toml::from_str::<Wrapper>("value = true").is_err());
+    }
+
+    #[test]
+    fn fallback_cannot_expand_the_candidate_set_beyond_four() {
+        let mut config = WebConfig {
+            carrier: WebCarrier::Https,
+            carriers: WebCarriers::Enabled(vec![
+                WebCarrier::HttpsLanes,
+                WebCarrier::Websocket,
+                WebCarrier::WebsocketLanes,
+                WebCarrier::Https,
+            ]),
+            ..Default::default()
+        };
+        assert_eq!(validate(&config).unwrap().len(), 4);
+
+        config.carriers = WebCarriers::Enabled(vec![
+            WebCarrier::HttpsLanes,
+            WebCarrier::Websocket,
+            WebCarrier::WebsocketLanes,
+        ]);
+        assert_eq!(validate(&config).unwrap().len(), 4);
+    }
+
+    #[test]
+    fn deadlines_are_cumulative_and_bounded_by_bootstrap_lifetime() {
+        let mut config = WebConfig::default();
+        config.timeouts.carrier_negotiation_deadlines_secs = [3, 3, 8, 12];
+        assert!(validate(&config).is_err());
+        config.timeouts.carrier_negotiation_deadlines_secs = [3, 5, 8, 121];
+        assert!(validate(&config).is_err());
+        config.timeouts.carrier_negotiation_deadlines_secs = [3, 5, 8, 89];
+        assert!(validate(&config).is_err());
+        config.timeouts.carrier_negotiation_deadlines_secs = [3, 5, 8, 88];
+        assert!(validate(&config).is_ok());
+    }
+}

src/config/load/validate_web/timeouts.rs

@@ -0,0 +1,62 @@
+use super::*;
+
+/// Validates WEB request, learning, and lifecycle timeouts.
+pub(super) fn validate(timeouts: &WebTimeoutsConfig) -> Result<()> {
+    let values = [
+        ("header_secs", timeouts.header_secs),
+        ("body_secs", timeouts.body_secs),
+        ("stream_handshake_secs", timeouts.stream_handshake_secs),
+        ("stream_first_byte_secs", timeouts.stream_first_byte_secs),
+        ("long_poll_secs", timeouts.long_poll_secs),
+        ("lane_open_wait_secs", timeouts.lane_open_wait_secs),
+        ("carrier_health_secs", timeouts.carrier_health_secs),
+        ("websocket_upgrade_secs", timeouts.websocket_upgrade_secs),
+        ("websocket_open_secs", timeouts.websocket_open_secs),
+        ("websocket_write_secs", timeouts.websocket_write_secs),
+        (
+            "websocket_backpressure_secs",
+            timeouts.websocket_backpressure_secs,
+        ),
+        ("websocket_eviction_secs", timeouts.websocket_eviction_secs),
+        ("bootstrap_lifetime_secs", timeouts.bootstrap_lifetime_secs),
+        ("reconnect_grace_secs", timeouts.reconnect_grace_secs),
+        ("http_idle_secs", timeouts.http_idle_secs),
+        ("shutdown_secs", timeouts.shutdown_secs),
+        ("decoy_header_secs", timeouts.decoy_header_secs),
+    ];
+    if let Some((field, _)) = values
+        .into_iter()
+        .find(|(_, value)| !(1..=3600).contains(value))
+    {
+        return config_error(&format!("web.timeouts.{field} must be within [1, 3600]"));
+    }
+    if !(2..=86_400).contains(&timeouts.carrier_learning_secs) {
+        return config_error("web.timeouts.carrier_learning_secs must be within [2, 86400]");
+    }
+    if timeouts.stream_first_byte_secs > 300 {
+        return config_error("web.timeouts.stream_first_byte_secs must be within [1, 300]");
+    }
+    if timeouts.websocket_upgrade_secs > 60 {
+        return config_error("web.timeouts.websocket_upgrade_secs must be within [1, 60]");
+    }
+    if timeouts.websocket_open_secs > 300 {
+        return config_error("web.timeouts.websocket_open_secs must be within [1, 300]");
+    }
+    if timeouts.lane_open_wait_secs > timeouts.long_poll_secs {
+        return config_error("web.timeouts.lane_open_wait_secs must not exceed long_poll_secs");
+    }
+    if timeouts.carrier_health_secs > timeouts.reconnect_grace_secs {
+        return config_error(
+            "web.timeouts.carrier_health_secs must not exceed reconnect_grace_secs",
+        );
+    }
+    let request_deadline = timeouts
+        .header_secs
+        .max(timeouts.body_secs)
+        .max(timeouts.long_poll_secs)
+        .max(timeouts.decoy_header_secs);
+    if request_deadline >= timeouts.http_idle_secs {
+        return config_error("web.timeouts request deadlines must be lower than http_idle_secs");
+    }
+    Ok(())
+}

src/config/load/validate_web/websocket.rs

@@ -7,7 +7,7 @@ const WEBSOCKET_FRAME_OVERHEAD_BYTES: usize = 14;
 
 /// Validates WebSocket admission, memory, and deadline invariants.
 pub(super) fn validate(
-    carrier: WebCarrier,
+    carriers: &[WebCarrier],
     limits: &WebLimitsConfig,
     timeouts: &WebTimeoutsConfig,
 ) -> Result<()> {
@@ -27,7 +27,7 @@ pub(super) fn validate(
             "web.timeouts.websocket_eviction_secs must not exceed websocket_write_secs",
         );
     }
-    if !carrier.uses_websocket() {
+    if !carriers.iter().any(|carrier| carrier.uses_websocket()) {
         return Ok(());
     }
     if limits.carrier_batch_bytes > MAX_WEBSOCKET_BATCH_BYTES {
@@ -42,6 +42,14 @@ pub(super) fn validate(
             "WebSocket carriers require websocket_http_connection_reserve within [1, max_http_connections)",
         );
     }
+    let websocket_capacity = limits
+        .max_http_connections
+        .saturating_sub(limits.websocket_http_connection_reserve);
+    if limits.max_websocket_evictions_in_flight > websocket_capacity {
+        return config_error(
+            "web.limits.max_websocket_evictions_in_flight must not exceed WebSocket connection capacity",
+        );
+    }
     let socket_base = WEBSOCKET_IO_BUFFER_BYTES
         .checked_mul(2)
         .and_then(|value| value.checked_add(WEBSOCKET_DRIVER_OVERHEAD_BYTES))

src/config/tests/load_basic_tests/web_tests.rs

@@ -49,6 +49,88 @@ fn web_config_builds_canonical_runtime_snapshot() {
     assert_eq!(vhost.profiles[0].max_streams_per_session, 16);
     assert_eq!(vhost.profiles[0].key_fingerprint.len(), 16);
     assert_ne!(vhost.profiles[0].key_fingerprint, "0001020304050607");
+    assert!(!vhost.profiles[0].carrier_negotiation_enabled);
+    assert_eq!(
+        vhost.profiles[0].carriers.as_ref(),
+        [WebCarrier::HttpsLanes]
+    );
+}
+
+#[test]
+fn web_carriers_missing_or_false_disable_negotiation() {
+    let missing = load_config_from_temp_toml(WEB_CONFIG);
+    assert!(!missing.web.carrier_negotiation_enabled());
+    assert!(!missing.web.runtime.unwrap().profiles[0].carrier_learning);
+
+    let disabled = WEB_CONFIG.replace(
+        "carrier = \"https-lanes\"",
+        "carrier = \"https-lanes\"\ncarriers = false",
+    );
+    let disabled = load_config_from_temp_toml(&disabled);
+    assert!(!disabled.web.carrier_negotiation_enabled());
+    assert!(!disabled.web.runtime.as_ref().unwrap().profiles[0].carrier_learning);
+    assert_eq!(
+        disabled.web.runtime.unwrap().profiles[0].carriers.as_ref(),
+        [WebCarrier::HttpsLanes]
+    );
+}
+
+#[test]
+fn web_carrier_array_enables_ordered_negotiation_and_appends_fallback() {
+    let configured = WEB_CONFIG.replace(
+        "carrier = \"https-lanes\"",
+        "carrier = \"https-lanes\"\ncarriers = [\"websocket\", \"https\"]\ncarrier_learning = false",
+    );
+    let config = load_config_from_temp_toml(&configured);
+    assert!(config.web.carrier_negotiation_enabled());
+    assert!(!config.web.carrier_learning);
+    let profile = &config.web.runtime.unwrap().profiles[0];
+    assert_eq!(
+        profile.carriers.as_ref(),
+        [
+            WebCarrier::Websocket,
+            WebCarrier::Https,
+            WebCarrier::HttpsLanes
+        ]
+    );
+    assert!(!profile.carrier_learning);
+}
+
+#[test]
+fn web_carriers_reject_true_empty_and_duplicates() {
+    for value in ["true", "[]", "[\"https\", \"https\"]"] {
+        let invalid = WEB_CONFIG.replace(
+            "carrier = \"https-lanes\"",
+            &format!("carrier = \"https-lanes\"\ncarriers = {value}"),
+        );
+        assert!(load_config_error_from_temp_toml(&invalid).contains("web.carriers"));
+    }
+}
+
+#[test]
+fn web_carrier_deadlines_and_learning_window_are_configurable() {
+    let configured = WEB_CONFIG.replace(
+        "[[web.vhosts]]",
+        "[web.timeouts]\ncarrier_negotiation_deadlines_secs = [1, 2, 4, 9]\ncarrier_learning_secs = 30\n\n[[web.vhosts]]",
+    );
+    let config = load_config_from_temp_toml(&configured);
+    assert_eq!(
+        config.web.timeouts.carrier_negotiation_deadlines_secs,
+        [1, 2, 4, 9]
+    );
+    assert_eq!(config.web.timeouts.carrier_learning_secs, 30);
+}
+
+#[test]
+fn web_carrier_learning_capacity_must_remain_nonzero() {
+    let invalid = WEB_CONFIG.replace(
+        "[[web.vhosts]]",
+        "[web.limits]\nmax_carrier_learning_entries = 0\n\n[[web.vhosts]]",
+    );
+    assert!(
+        load_config_error_from_temp_toml(&invalid)
+            .contains("web.limits.max_carrier_learning_entries")
+    );
 }
 
 #[test]
@@ -106,7 +188,7 @@ fn https_lanes_requires_separate_poll_and_control_handler_capacity() {
         "carrier = \"https-lanes\"\n\n[web.limits]\nmax_http_handlers = 1\nmax_body_readers = 1",
     );
     let error = load_config_error_from_temp_toml(&invalid);
-    assert!(error.contains("web.carrier=https-lanes requires"));
+    assert!(error.contains("WEB https-lanes candidates require"));
 }
 
 #[test]

src/config/types.rs

@@ -24,6 +24,8 @@ mod network;
 mod policies;
 mod server;
 mod web;
+// WEB carrier tokens and fixed-slot policy helpers remain independent from bulky config types.
+mod web_carrier;
 // WEB debug capture policy is reusable by config reload and process storage.
 mod web_debug;
 
@@ -51,13 +53,15 @@ pub use server::{
 };
 #[allow(unused_imports)]
 pub use web::{
-    WebCarrier, WebConfig, WebDecoyConfig, WebLimitsConfig, WebProfileConfig, WebSecretMode,
-    WebTimeoutsConfig, WebVhostConfig,
+    WebCarrierNegotiationAggressiveness, WebConfig, WebDecoyConfig, WebLimitsConfig,
+    WebProfileConfig, WebSecretMode, WebTimeoutsConfig, WebVhostConfig,
 };
 pub(crate) use web::{
     WebRuntimeConfig, WebRuntimeDecoy, WebRuntimeProfile, WebRuntimeVhost, WebStaticAsset,
     WebStaticSite,
 };
+#[allow(unused_imports)]
+pub use web_carrier::{WebCarrier, WebCarriers};
 pub(crate) use web_debug::web_debug_fits_limits;
 pub use web_debug::{WebDebugBodyCapture, WebDebugConfig};
 

src/config/types/web.rs

@@ -6,8 +6,13 @@ use std::sync::Arc;
 use bytes::Bytes;
 use serde::{Deserialize, Serialize};
 
+use super::web_carrier::{WebCarrier, WebCarriers};
 use super::web_debug::WebDebugConfig;
 
+// Serialized WEB defaults remain separate from the runtime data model.
+mod defaults;
+use defaults::*;
+
 /// Client-facing secret representation used to derive a WEB capability.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
 #[serde(rename_all = "lowercase")]
@@ -18,48 +23,6 @@ pub enum WebSecretMode {
     Dd,
 }
 
-/// Carrier selected for newly issued WEB bridge sessions.
-#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Hash, Serialize, Deserialize)]
-#[serde(rename_all = "kebab-case")]
-pub enum WebCarrier {
-    /// Serialize all logical streams through one uplink and one downlink sequence.
-    #[default]
-    Https,
-    /// Give every logical stream independent HTTPS sequencing and polling state.
-    HttpsLanes,
-    /// Multiplex all logical streams over one ordered WebSocket.
-    Websocket,
-    /// Give every logical stream an independently owned WebSocket lane.
-    WebsocketLanes,
-}
-
-impl WebCarrier {
-    /// Returns the exact carrier token advertised to the browser bridge.
-    pub(crate) const fn as_str(self) -> &'static str {
-        match self {
-            Self::Https => "https",
-            Self::HttpsLanes => "https-lanes",
-            Self::Websocket => "websocket",
-            Self::WebsocketLanes => "websocket-lanes",
-        }
-    }
-
-    /// Returns whether one carrier owns independent state per logical stream.
-    pub(crate) const fn uses_lanes(self) -> bool {
-        matches!(self, Self::HttpsLanes | Self::WebsocketLanes)
-    }
-
-    /// Returns whether carrier messages use RFC 6455 instead of HTTP bodies.
-    pub(crate) const fn uses_websocket(self) -> bool {
-        matches!(self, Self::Websocket | Self::WebsocketLanes)
-    }
-
-    /// Returns whether all logical streams share one carrier state machine.
-    pub(crate) const fn is_multiplexed(self) -> bool {
-        matches!(self, Self::Https | Self::Websocket)
-    }
-}
-
 /// One access user explicitly exposed through a WEB virtual host.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct WebProfileConfig {
@@ -135,6 +98,15 @@ pub struct WebLimitsConfig {
     /// Process-wide concurrently executing HTTP handler ceiling.
     #[serde(default = "default_web_max_http_handlers")]
     pub max_http_handlers: usize,
+    /// Per-session ceiling for downlink polls waiting for a lane OPEN.
+    #[serde(default = "default_web_max_lane_open_waits_per_session")]
+    pub max_lane_open_waits_per_session: usize,
+    /// Queued and resident DATA bytes allowed for one independent lane.
+    #[serde(default = "default_web_pending_bytes_per_lane")]
+    pub pending_bytes_per_lane: usize,
+    /// Queued and resident DATA items allowed for one independent lane.
+    #[serde(default = "default_web_pending_items_per_lane")]
+    pub pending_items_per_lane: usize,
     /// Process-wide transient WebSocket byte sub-budget inside pending bytes.
     #[serde(default = "default_web_websocket_bytes_global")]
     pub websocket_bytes_global: usize,
@@ -147,6 +119,12 @@ pub struct WebLimitsConfig {
     /// Accepted HTTP connections that WebSocket upgrades must leave available.
     #[serde(default = "default_web_websocket_http_connection_reserve")]
     pub websocket_http_connection_reserve: usize,
+    /// Concurrent pressure-eviction claims allowed process-wide.
+    #[serde(default = "default_web_max_websocket_evictions_in_flight")]
+    pub max_websocket_evictions_in_flight: usize,
+    /// Process-wide bounded carrier-learning evidence entry ceiling.
+    #[serde(default = "default_web_max_carrier_learning_entries")]
+    pub max_carrier_learning_entries: usize,
     /// Process-wide concurrently collected request body ceiling.
     #[serde(default = "default_web_max_body_readers")]
     pub max_body_readers: usize,
@@ -216,7 +194,7 @@ pub struct WebLimitsConfig {
     /// Process-wide retained and in-flight WEB debug byte ceiling.
     #[serde(default = "default_web_debug_bytes_global")]
     pub debug_bytes_global: usize,
-    /// Declared process envelope for HTTP heads, bodies, queues, and static snapshots.
+    /// Declared process envelope for HTTP, queues, lane state, learning, and static snapshots.
     #[serde(default = "default_web_memory_envelope_bytes")]
     pub memory_envelope_bytes: usize,
     /// Sustained process-wide bootstrap issuance rate.
@@ -249,10 +227,15 @@ impl Default for WebLimitsConfig {
             max_frames_per_body: default_web_max_frames_per_body(),
             max_http_connections: default_web_max_http_connections(),
             max_http_handlers: default_web_max_http_handlers(),
+            max_lane_open_waits_per_session: default_web_max_lane_open_waits_per_session(),
+            pending_bytes_per_lane: default_web_pending_bytes_per_lane(),
+            pending_items_per_lane: default_web_pending_items_per_lane(),
             websocket_bytes_global: default_web_websocket_bytes_global(),
             websocket_admission_watermark_pct: default_web_websocket_admission_watermark_pct(),
             websocket_eviction_watermark_pct: default_web_websocket_eviction_watermark_pct(),
             websocket_http_connection_reserve: default_web_websocket_http_connection_reserve(),
+            max_websocket_evictions_in_flight: default_web_max_websocket_evictions_in_flight(),
+            max_carrier_learning_entries: default_web_max_carrier_learning_entries(),
             max_body_readers: default_web_max_body_readers(),
             max_body_bytes_global: default_web_max_body_bytes_global(),
             max_sessions_global: default_web_max_sessions_global(),
@@ -299,9 +282,24 @@ pub struct WebTimeoutsConfig {
     /// Deadline from the first inner byte through MTProxy authentication.
     #[serde(default = "default_web_stream_handshake_timeout_secs")]
     pub stream_handshake_secs: u64,
+    /// Absolute deadline for receiving the first inner MTProxy byte.
+    #[serde(default = "default_web_stream_first_byte_secs")]
+    pub stream_first_byte_secs: u64,
     /// Maximum wait for one empty downlink long poll.
     #[serde(default = "default_web_long_poll_timeout_secs")]
     pub long_poll_secs: u64,
+    /// Grace for a canonical downlink poll that races its lane OPEN.
+    #[serde(default = "default_web_lane_open_wait_secs")]
+    pub lane_open_wait_secs: u64,
+    /// Post-commit observation interval required before learning succeeds.
+    #[serde(default = "default_web_carrier_health_secs")]
+    pub carrier_health_secs: u64,
+    /// Maximum wait for Hyper to transfer an accepted WebSocket upgrade.
+    #[serde(default = "default_web_websocket_upgrade_secs")]
+    pub websocket_upgrade_secs: u64,
+    /// Absolute deadline for the first carrier binary message after upgrade.
+    #[serde(default = "default_web_websocket_open_secs")]
+    pub websocket_open_secs: u64,
     /// Maximum wait for one WebSocket write to complete.
     #[serde(default = "default_web_websocket_write_secs")]
     pub websocket_write_secs: u64,
@@ -311,6 +309,12 @@ pub struct WebTimeoutsConfig {
     /// Maximum graceful close wait for an evicted WebSocket.
     #[serde(default = "default_web_websocket_eviction_secs")]
     pub websocket_eviction_secs: u64,
+    /// Cumulative carrier-attempt deadlines for up to four unique candidates.
+    #[serde(default = "default_web_carrier_negotiation_deadlines_secs")]
+    pub carrier_negotiation_deadlines_secs: [u64; 4],
+    /// Fixed process-local carrier-learning evidence lifetime.
+    #[serde(default = "default_web_carrier_learning_secs")]
+    pub carrier_learning_secs: u64,
     /// Lifetime of an unused bootstrap credential and closed-token replay marker.
     #[serde(default = "default_web_bootstrap_lifetime_secs")]
     pub bootstrap_lifetime_secs: u64,
@@ -334,10 +338,17 @@ impl Default for WebTimeoutsConfig {
             header_secs: default_web_header_timeout_secs(),
             body_secs: default_web_body_timeout_secs(),
             stream_handshake_secs: default_web_stream_handshake_timeout_secs(),
+            stream_first_byte_secs: default_web_stream_first_byte_secs(),
             long_poll_secs: default_web_long_poll_timeout_secs(),
+            lane_open_wait_secs: default_web_lane_open_wait_secs(),
+            carrier_health_secs: default_web_carrier_health_secs(),
+            websocket_upgrade_secs: default_web_websocket_upgrade_secs(),
+            websocket_open_secs: default_web_websocket_open_secs(),
             websocket_write_secs: default_web_websocket_write_secs(),
             websocket_backpressure_secs: default_web_websocket_backpressure_secs(),
             websocket_eviction_secs: default_web_websocket_eviction_secs(),
+            carrier_negotiation_deadlines_secs: default_web_carrier_negotiation_deadlines_secs(),
+            carrier_learning_secs: default_web_carrier_learning_secs(),
             bootstrap_lifetime_secs: default_web_bootstrap_lifetime_secs(),
             reconnect_grace_secs: default_web_reconnect_grace_secs(),
             http_idle_secs: default_web_http_idle_secs(),
@@ -347,15 +358,37 @@ impl Default for WebTimeoutsConfig {
     }
 }
 
+/// Sensitivity of process-local carrier-learning evidence.
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum WebCarrierNegotiationAggressiveness {
+    /// Require broad evidence and never rank by client IP.
+    #[default]
+    Conservative,
+    /// Use moderate User-Agent, client-IP, and profile thresholds.
+    Balanced,
+    /// React to the first bounded evidence sample.
+    Aggressive,
+}
+
 /// WEB ingress, carrier, fallback, and lifecycle configuration.
-#[derive(Debug, Clone, Default, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct WebConfig {
     /// Enables issuance of new WEB bridge and session credentials.
     #[serde(default)]
     pub enabled: bool,
-    /// Carrier selected for newly issued WEB bridge sessions.
+    /// Sole carrier when negotiation is disabled and final fallback when enabled.
     #[serde(default)]
     pub carrier: WebCarrier,
+    /// Ordered carriers considered by server-side negotiation before the fallback carrier.
+    #[serde(default)]
+    pub carriers: WebCarriers,
+    /// Enables bounded process-local carrier learning for automatic sessions.
+    #[serde(default = "default_web_carrier_learning")]
+    pub carrier_learning: bool,
+    /// Controls the evidence thresholds used by automatic carrier ranking.
+    #[serde(default)]
+    pub carrier_negotiation_aggressiveness: WebCarrierNegotiationAggressiveness,
     /// Hard process and protocol limits.
     #[serde(default)]
     pub limits: WebLimitsConfig,
@@ -373,6 +406,44 @@ pub struct WebConfig {
     pub(crate) runtime: Option<Arc<WebRuntimeConfig>>,
 }
 
+impl WebConfig {
+    /// Returns the configured negotiation order with the fallback appended once.
+    pub(crate) fn carrier_candidates(&self) -> Vec<WebCarrier> {
+        let Some(configured) = self.carriers.enabled() else {
+            return vec![self.carrier];
+        };
+        let mut candidates = configured
+            .iter()
+            .copied()
+            .filter(|carrier| *carrier != self.carrier)
+            .collect::<Vec<_>>();
+        candidates.push(self.carrier);
+        candidates
+    }
+
+    /// Returns whether the explicit candidate list enables auto-negotiation.
+    pub(crate) fn carrier_negotiation_enabled(&self) -> bool {
+        self.carriers.enabled().is_some()
+    }
+}
+
+impl Default for WebConfig {
+    fn default() -> Self {
+        Self {
+            enabled: false,
+            carrier: WebCarrier::default(),
+            carriers: WebCarriers::default(),
+            carrier_learning: default_web_carrier_learning(),
+            carrier_negotiation_aggressiveness: WebCarrierNegotiationAggressiveness::default(),
+            limits: WebLimitsConfig::default(),
+            debug: WebDebugConfig::default(),
+            timeouts: WebTimeoutsConfig::default(),
+            vhosts: Vec::new(),
+            runtime: None,
+        }
+    }
+}
+
 /// Precomputed WEB configuration consumed by listener hot paths.
 #[derive(Debug)]
 pub(crate) struct WebRuntimeConfig {
@@ -406,8 +477,16 @@ pub(crate) struct WebRuntimeProfile {
     pub(crate) user: String,
     /// Client secret representation and inner protocol policy.
     pub(crate) secret_mode: WebSecretMode,
-    /// Carrier frozen into bridge and session state at issuance time.
+    /// Sole carrier or final fallback frozen into the issued bridge policy.
     pub(crate) carrier: WebCarrier,
+    /// Whether an explicit carrier list enabled automatic negotiation.
+    pub(crate) carrier_negotiation_enabled: bool,
+    /// Whether automatic outcomes consult and update process-local evidence.
+    pub(crate) carrier_learning: bool,
+    /// Ordered negotiation candidates including the fallback carrier exactly once.
+    pub(crate) carriers: Arc<[WebCarrier]>,
+    /// Cumulative carrier-attempt deadlines frozen when the bridge is issued.
+    pub(crate) carrier_negotiation_deadlines_secs: [u64; 4],
     /// HMAC-derived bridge capability.
     pub(crate) capability: [u8; 32],
     /// Non-secret domain-separated client-secret fingerprint for debugging.
@@ -446,93 +525,3 @@ pub(crate) struct WebStaticAsset {
     /// Strong SHA-256 entity tag.
     pub(crate) etag: String,
 }
-
-fn default_web_static_index() -> String {
-    "index.html".to_string()
-}
-
-macro_rules! usize_default {
-    ($name:ident, $value:expr) => {
-        fn $name() -> usize {
-            $value
-        }
-    };
-}
-
-macro_rules! u32_default {
-    ($name:ident, $value:expr) => {
-        fn $name() -> u32 {
-            $value
-        }
-    };
-}
-
-macro_rules! u8_default {
-    ($name:ident, $value:expr) => {
-        fn $name() -> u8 {
-            $value
-        }
-    };
-}
-
-macro_rules! u64_default {
-    ($name:ident, $value:expr) => {
-        fn $name() -> u64 {
-            $value
-        }
-    };
-}
-
-usize_default!(default_web_max_header_bytes, 16 * 1024);
-usize_default!(default_web_max_body_bytes, 2 * 1024 * 1024);
-usize_default!(default_web_max_frame_payload_bytes, 1024 * 1024);
-usize_default!(default_web_carrier_batch_bytes, 2 * 1024 * 1024);
-usize_default!(default_web_max_frames_per_body, 4096);
-usize_default!(default_web_max_http_connections, 1024);
-usize_default!(default_web_max_http_handlers, 512);
-usize_default!(default_web_websocket_bytes_global, 256 * 1024 * 1024);
-u8_default!(default_web_websocket_admission_watermark_pct, 75);
-u8_default!(default_web_websocket_eviction_watermark_pct, 90);
-usize_default!(default_web_websocket_http_connection_reserve, 64);
-usize_default!(default_web_max_body_readers, 32);
-usize_default!(default_web_max_body_bytes_global, 64 * 1024 * 1024);
-usize_default!(default_web_max_sessions_global, 128);
-usize_default!(default_web_max_sessions_per_ip, 16);
-usize_default!(default_web_max_streams_per_session, 128);
-usize_default!(default_web_max_streams_global, 4096);
-usize_default!(default_web_max_stream_handshakes, 256);
-usize_default!(default_web_max_tombstones, 4096);
-usize_default!(default_web_pending_bytes_per_session, 32 * 1024 * 1024);
-usize_default!(default_web_pending_bytes_global, 512 * 1024 * 1024);
-usize_default!(default_web_pending_items_per_session, 16 * 1024);
-usize_default!(default_web_pending_items_global, 256 * 1024);
-usize_default!(default_web_control_bytes_per_session, 256 * 1024);
-usize_default!(default_web_control_bytes_global, 16 * 1024 * 1024);
-usize_default!(default_web_max_bootstraps_global, 512);
-usize_default!(default_web_max_bootstraps_per_ip, 64);
-usize_default!(default_web_max_vhosts, 8);
-usize_default!(default_web_max_profiles, 32);
-usize_default!(default_web_max_static_files, 4096);
-usize_default!(default_web_max_static_file_bytes, 8 * 1024 * 1024);
-usize_default!(default_web_max_static_bytes, 64 * 1024 * 1024);
-usize_default!(default_web_debug_records_capacity, 65_536);
-usize_default!(default_web_debug_bytes_global, 64 * 1024 * 1024);
-usize_default!(default_web_memory_envelope_bytes, 768 * 1024 * 1024);
-u32_default!(default_web_new_bootstraps_per_minute, 1200);
-u32_default!(default_web_new_bootstraps_burst, 256);
-u32_default!(default_web_new_sessions_per_minute, 600);
-u32_default!(default_web_new_sessions_burst, 128);
-u32_default!(default_web_new_streams_per_minute, 6000);
-u32_default!(default_web_new_streams_burst, 512);
-u64_default!(default_web_header_timeout_secs, 10);
-u64_default!(default_web_body_timeout_secs, 30);
-u64_default!(default_web_stream_handshake_timeout_secs, 10);
-u64_default!(default_web_long_poll_timeout_secs, 25);
-u64_default!(default_web_websocket_write_secs, 30);
-u64_default!(default_web_websocket_backpressure_secs, 30);
-u64_default!(default_web_websocket_eviction_secs, 1);
-u64_default!(default_web_bootstrap_lifetime_secs, 120);
-u64_default!(default_web_reconnect_grace_secs, 120);
-u64_default!(default_web_http_idle_secs, 75);
-u64_default!(default_web_shutdown_secs, 15);
-u64_default!(default_web_decoy_header_timeout_secs, 30);

src/config/types/web/defaults.rs

@@ -0,0 +1,106 @@
+pub(super) fn default_web_static_index() -> String {
+    "index.html".to_string()
+}
+
+macro_rules! usize_default {
+    ($name:ident, $value:expr) => {
+        pub(super) fn $name() -> usize {
+            $value
+        }
+    };
+}
+
+macro_rules! u32_default {
+    ($name:ident, $value:expr) => {
+        pub(super) fn $name() -> u32 {
+            $value
+        }
+    };
+}
+
+macro_rules! u8_default {
+    ($name:ident, $value:expr) => {
+        pub(super) fn $name() -> u8 {
+            $value
+        }
+    };
+}
+
+macro_rules! u64_default {
+    ($name:ident, $value:expr) => {
+        pub(super) fn $name() -> u64 {
+            $value
+        }
+    };
+}
+
+usize_default!(default_web_max_header_bytes, 16 * 1024);
+usize_default!(default_web_max_body_bytes, 2 * 1024 * 1024);
+usize_default!(default_web_max_frame_payload_bytes, 1024 * 1024);
+usize_default!(default_web_carrier_batch_bytes, 2 * 1024 * 1024);
+usize_default!(default_web_max_frames_per_body, 4096);
+usize_default!(default_web_max_http_connections, 1024);
+usize_default!(default_web_max_http_handlers, 512);
+usize_default!(default_web_max_lane_open_waits_per_session, 16);
+usize_default!(default_web_pending_bytes_per_lane, 8 * 1024 * 1024);
+usize_default!(default_web_pending_items_per_lane, 1024);
+usize_default!(default_web_websocket_bytes_global, 256 * 1024 * 1024);
+u8_default!(default_web_websocket_admission_watermark_pct, 75);
+u8_default!(default_web_websocket_eviction_watermark_pct, 90);
+usize_default!(default_web_websocket_http_connection_reserve, 64);
+usize_default!(default_web_max_websocket_evictions_in_flight, 8);
+usize_default!(default_web_max_carrier_learning_entries, 4096);
+usize_default!(default_web_max_body_readers, 32);
+usize_default!(default_web_max_body_bytes_global, 64 * 1024 * 1024);
+usize_default!(default_web_max_sessions_global, 128);
+usize_default!(default_web_max_sessions_per_ip, 16);
+usize_default!(default_web_max_streams_per_session, 128);
+usize_default!(default_web_max_streams_global, 4096);
+usize_default!(default_web_max_stream_handshakes, 256);
+usize_default!(default_web_max_tombstones, 4096);
+usize_default!(default_web_pending_bytes_per_session, 32 * 1024 * 1024);
+usize_default!(default_web_pending_bytes_global, 512 * 1024 * 1024);
+usize_default!(default_web_pending_items_per_session, 16 * 1024);
+usize_default!(default_web_pending_items_global, 256 * 1024);
+usize_default!(default_web_control_bytes_per_session, 256 * 1024);
+usize_default!(default_web_control_bytes_global, 16 * 1024 * 1024);
+usize_default!(default_web_max_bootstraps_global, 512);
+usize_default!(default_web_max_bootstraps_per_ip, 64);
+usize_default!(default_web_max_vhosts, 8);
+usize_default!(default_web_max_profiles, 32);
+usize_default!(default_web_max_static_files, 4096);
+usize_default!(default_web_max_static_file_bytes, 8 * 1024 * 1024);
+usize_default!(default_web_max_static_bytes, 64 * 1024 * 1024);
+usize_default!(default_web_debug_records_capacity, 65_536);
+usize_default!(default_web_debug_bytes_global, 64 * 1024 * 1024);
+usize_default!(default_web_memory_envelope_bytes, 1280 * 1024 * 1024);
+u32_default!(default_web_new_bootstraps_per_minute, 1200);
+u32_default!(default_web_new_bootstraps_burst, 256);
+u32_default!(default_web_new_sessions_per_minute, 600);
+u32_default!(default_web_new_sessions_burst, 128);
+u32_default!(default_web_new_streams_per_minute, 6000);
+u32_default!(default_web_new_streams_burst, 512);
+u64_default!(default_web_header_timeout_secs, 10);
+u64_default!(default_web_body_timeout_secs, 30);
+u64_default!(default_web_stream_handshake_timeout_secs, 10);
+u64_default!(default_web_stream_first_byte_secs, 30);
+u64_default!(default_web_long_poll_timeout_secs, 25);
+u64_default!(default_web_lane_open_wait_secs, 2);
+u64_default!(default_web_carrier_health_secs, 30);
+u64_default!(default_web_websocket_upgrade_secs, 5);
+u64_default!(default_web_websocket_open_secs, 15);
+u64_default!(default_web_websocket_write_secs, 30);
+u64_default!(default_web_websocket_backpressure_secs, 30);
+u64_default!(default_web_websocket_eviction_secs, 1);
+pub(super) fn default_web_carrier_negotiation_deadlines_secs() -> [u64; 4] {
+    [3, 5, 8, 12]
+}
+u64_default!(default_web_carrier_learning_secs, 600);
+pub(super) fn default_web_carrier_learning() -> bool {
+    true
+}
+u64_default!(default_web_bootstrap_lifetime_secs, 120);
+u64_default!(default_web_reconnect_grace_secs, 120);
+u64_default!(default_web_http_idle_secs, 75);
+u64_default!(default_web_shutdown_secs, 15);
+u64_default!(default_web_decoy_header_timeout_secs, 30);

src/config/types/web_carrier.rs

@@ -0,0 +1,115 @@
+use serde::{Deserialize, Serialize};
+
+/// Carrier selected for one newly issued WEB relay session.
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub enum WebCarrier {
+    /// Serialize all logical streams through one uplink and one downlink sequence.
+    #[default]
+    Https,
+    /// Give every logical stream independent HTTPS sequencing and polling state.
+    HttpsLanes,
+    /// Multiplex all logical streams over one ordered WebSocket.
+    Websocket,
+    /// Give every logical stream an independently owned WebSocket lane.
+    WebsocketLanes,
+}
+
+impl WebCarrier {
+    /// Every carrier supported by the WEB v1 bridge.
+    pub(crate) const ALL: [Self; 4] = [
+        Self::Https,
+        Self::HttpsLanes,
+        Self::Websocket,
+        Self::WebsocketLanes,
+    ];
+
+    /// Returns the exact carrier token advertised to the browser bridge.
+    pub(crate) const fn as_str(self) -> &'static str {
+        match self {
+            Self::Https => "https",
+            Self::HttpsLanes => "https-lanes",
+            Self::Websocket => "websocket",
+            Self::WebsocketLanes => "websocket-lanes",
+        }
+    }
+
+    /// Returns the stable fixed-slot index used by bounded learning state.
+    pub(crate) const fn index(self) -> usize {
+        match self {
+            Self::Https => 0,
+            Self::HttpsLanes => 1,
+            Self::Websocket => 2,
+            Self::WebsocketLanes => 3,
+        }
+    }
+
+    /// Returns whether one carrier owns independent state per logical stream.
+    pub(crate) const fn uses_lanes(self) -> bool {
+        matches!(self, Self::HttpsLanes | Self::WebsocketLanes)
+    }
+
+    /// Returns whether carrier messages use RFC 6455 instead of HTTP bodies.
+    pub(crate) const fn uses_websocket(self) -> bool {
+        matches!(self, Self::Websocket | Self::WebsocketLanes)
+    }
+
+    /// Returns whether all logical streams share one carrier state machine.
+    pub(crate) const fn is_multiplexed(self) -> bool {
+        matches!(self, Self::Https | Self::Websocket)
+    }
+}
+
+/// Optional ordered carrier list that enables server-side auto-negotiation.
+#[derive(Debug, Clone, Default, PartialEq, Eq)]
+pub enum WebCarriers {
+    /// Auto-negotiation is disabled and only `web.carrier` is used.
+    #[default]
+    Disabled,
+    /// Auto-negotiation uses this ordered candidate list before the fallback.
+    Enabled(Vec<WebCarrier>),
+}
+
+impl WebCarriers {
+    /// Returns the explicit candidate list when negotiation is enabled.
+    pub fn enabled(&self) -> Option<&[WebCarrier]> {
+        match self {
+            Self::Disabled => None,
+            Self::Enabled(carriers) => Some(carriers),
+        }
+    }
+}
+
+impl Serialize for WebCarriers {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        match self {
+            Self::Disabled => false.serialize(serializer),
+            Self::Enabled(carriers) => carriers.serialize(serializer),
+        }
+    }
+}
+
+impl<'de> Deserialize<'de> for WebCarriers {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        #[derive(Deserialize)]
+        #[serde(untagged)]
+        enum Repr {
+            Flag(bool),
+            List(Vec<WebCarrier>),
+        }
+
+        match Repr::deserialize(deserializer)? {
+            Repr::Flag(false) => Ok(Self::Disabled),
+            Repr::Flag(true) => Err(serde::de::Error::custom(
+                "web.carriers accepts false or a non-empty carrier array",
+            )),
+            Repr::List(carriers) => Ok(Self::Enabled(carriers)),
+        }
+    }
+}

src/web/bridge.rs

@@ -1,6 +1,5 @@
 use base64::Engine as _;
 
-use crate::config::WebCarrier;
 use crate::crypto::SecureRandom;
 
 /// Browser security policy for the transient Telegram Desktop bridge page.
@@ -14,14 +13,17 @@ pub(crate) struct BridgePage {
     pub(crate) content_security_policy: String,
 }
 
-/// Renders the selected HTTPS WEB carrier bridge with a fresh CSP nonce.
+/// Renders the bounded WEB carrier-negotiation bridge with a fresh CSP nonce.
+#[allow(clippy::too_many_arguments)]
 pub(crate) fn render(
     host: &str,
     bootstrap: &str,
     batch_limit: usize,
     queue_limit: usize,
     queue_items: usize,
-    carrier: WebCarrier,
+    negotiation_enabled: bool,
+    candidate_count: usize,
+    carrier_deadlines: [u64; 4],
     rng: &SecureRandom,
 ) -> BridgePage {
     let mut nonce = [0u8; 18];
@@ -34,7 +36,19 @@ pub(crate) fn render(
         .replace("__BATCH_LIMIT__", &batch_limit.to_string())
         .replace("__QUEUE_LIMIT__", &queue_limit.to_string())
         .replace("__QUEUE_ITEMS__", &queue_items.to_string())
-        .replace("__CARRIER__", carrier.as_str());
+        .replace(
+            "__NEGOTIATION_ENABLED__",
+            if negotiation_enabled { "true" } else { "false" },
+        )
+        .replace("__CANDIDATE_COUNT__", &candidate_count.to_string())
+        .replace(
+            "__CARRIER_DEADLINES__",
+            &carrier_deadlines
+                .iter()
+                .map(u64::to_string)
+                .collect::<Vec<_>>()
+                .join(","),
+        );
     BridgePage {
         body,
         content_security_policy: format!(
@@ -54,21 +68,32 @@ const DOCUMENT: &str = r##"<!doctype html>
 <script nonce="__NONCE__">
 (()=>{
 'use strict';
-const relayOrigin='https://__HOST__',bootstrap="__BOOTSTRAP__",carrier='__CARRIER__';
+const bootstrap="__BOOTSTRAP__";
+const relayOrigin='https://__HOST__',carrierCapabilities='https,https-lanes,websocket,websocket-lanes';
+const negotiationEnabled=__NEGOTIATION_ENABLED__,candidateCount=__CANDIDATE_COUNT__,candidateDeadlines=[__CARRIER_DEADLINES__];
+let negotiatedCandidateCount=candidateCount,negotiatedFinalDeadline=candidateDeadlines[3],negotiatedFrozen=false;
 const batchLimit=__BATCH_LIMIT__,queueLimit=__QUEUE_LIMIT__,queueItemLimit=__QUEUE_ITEMS__;
 const laneQueueLimit=Math.min(queueLimit,8388608),laneItemLimit=Math.min(queueItemLimit,1024),closedLaneLimit=4096;
 const fragment=location.hash,androidNonce=/^#android=([A-Za-z0-9_-]{43})$/.exec(fragment)?.[1]||'';
 history.replaceState(null,'',location.pathname);
-let initialized=false,closed=false,port=null,sessionToken='',createStarted=false,socket=null,socketReady=false;
+let initialized=false,closed=false,port=null,sessionToken='',cleanupToken='',createStarted=false,socket=null,socketReady=false,carrier='';
 let queuedBytes=0,queuedItems=0,upSequence=1,downCursor='0',upRunning=false,pollController=null;
+let helloFrame=null,welcomeSent=false,carrierAttempt=1,carrierFailure='',carrierCommitted=false;
+let negotiationStartedAt=0,carrierTimer=null,attemptController=null,attemptEpoch=1,candidateRunning=false,switching=false,currentAttempt=null;
 const pending=[],upPending=[],lanes=new Map(),closedLanes=new Set(),closedLaneOrder=[];
 const status=state=>{if(port&&!closed)port.postMessage({t:'status',state})};
-const pause=milliseconds=>new Promise(resolve=>setTimeout(resolve,milliseconds));
+const pause=(milliseconds,signal)=>new Promise((resolve,reject)=>{
+ if(signal&&signal.aborted){reject(new Error('request aborted'));return}
+ const timer=setTimeout(done,milliseconds);function done(){if(signal)signal.removeEventListener('abort',abort);resolve()}
+ function abort(){clearTimeout(timer);signal.removeEventListener('abort',abort);reject(new Error('request aborted'))}
+ if(signal)signal.addEventListener('abort',abort,{once:true});
+});
 const socketURL=()=>relayOrigin.replace(/^https:/,'wss:')+'/api/v1/ws';
 const options=(method,token,body,headers,signal,keepalive)=>({
  method,body,signal,keepalive:!!keepalive,mode:'same-origin',credentials:'omit',cache:'no-store',redirect:'error',referrerPolicy:'no-referrer',
  headers:Object.assign(token?{Authorization:'Bearer '+token}:{},body?{'Content-Type':'application/octet-stream'}:{},headers||{})
 });
+const attemptHeaders=(attempt,failure)=>negotiationEnabled?Object.assign({'X-Carrier-Capabilities':carrierCapabilities,'X-Carrier-Attempt':String(attempt)},failure?{'X-Carrier-Failure':failure}:{}):{};
 function reserve(data,lane){
  let buffered=socket?socket.bufferedAmount:0;for(const value of lanes.values())if(value.socket)buffered+=value.socket.bufferedAmount;
  if(!data.byteLength||data.byteLength>queueLimit-queuedBytes-buffered||queuedItems>=queueItemLimit)return false;
@@ -99,6 +124,27 @@ function splitFrames(value){
  }
  if(!result.length)throw new Error('empty frame batch');return result;
 }
+function findProbe(){
+ for(let index=0;index<pending.length;index++){
+  const value=pending[index],view=new DataView(value);let offset=0,frames=0;
+  while(offset<value.byteLength){
+   if(value.byteLength-offset<8||frames++>=4096)throw new Error('invalid frame batch');
+   const type=view.getUint8(offset),id=(view.getUint8(offset+1)<<16)|(view.getUint8(offset+2)<<8)|view.getUint8(offset+3);
+   const size=view.getUint32(offset+4),end=offset+8+size;
+   if((type===2&&!size)||size>1048576||end>value.byteLength)throw new Error('invalid frame');
+   if(type===1||type===2)return {source:value,index,start:offset,end,id,data:value.slice(offset,end)};
+   offset=end;
+  }
+ }
+ return null;
+}
+function consumeProbe(probe){
+ if(pending[probe.index]!==probe.source)throw new Error('stale carrier probe');
+ const before=probe.source.slice(0,probe.start),after=probe.source.slice(probe.end),remaining=before.byteLength+after.byteLength;
+ if(!remaining){pending.splice(probe.index,1);release(probe.end-probe.start,1,null);return}
+ const merged=new Uint8Array(remaining);merged.set(new Uint8Array(before),0);merged.set(new Uint8Array(after),before.byteLength);
+ pending[probe.index]=merged.buffer;release(probe.end-probe.start,0,null);
+}
 function joinPending(values,lane){
  let total=0,count=0,frames=0;
  while(count<values.length){
@@ -124,12 +170,13 @@ function retryAfterMs(response){
  if(Number.isFinite(when)){const delta=when-Date.now();return delta>0?Math.min(delta,30000):0}
  return 0;
 }
-async function request(path,makeOptions){
+async function request(path,frozenOptions){
  let delay=250,attempt=0;const deadline=Date.now()+90000;
  while(true){
-  const requestOptions=makeOptions(),controller=new AbortController(),external=requestOptions.signal;
+  const controller=new AbortController(),external=frozenOptions.signal;
+  if(closed||(external&&external.aborted))throw new Error('request aborted');
   const abort=()=>controller.abort();if(external)external.addEventListener('abort',abort,{once:true});
-  requestOptions.signal=controller.signal;const timer=setTimeout(abort,90000);
+  const requestOptions=Object.assign({},frozenOptions,{signal:controller.signal});const timer=setTimeout(abort,90000);
   let serviceUnavailable=false,wait=0;
   try{
    const response=await fetch(relayOrigin+path,requestOptions);
@@ -140,26 +187,129 @@ async function request(path,makeOptions){
    if(++attempt===9)throw new Error('carrier retry limit reached');
   }finally{clearTimeout(timer);if(external)external.removeEventListener('abort',abort)}
   if(serviceUnavailable&&Date.now()>=deadline)throw new Error('carrier retry limit reached');
-  status('reconnecting');await pause(wait||(delay+Math.floor(Math.random()*Math.max(1,delay/4))));
+  status('reconnecting');await pause(wait||(delay+Math.floor(Math.random()*Math.max(1,delay/4))),external);
+  if(closed||(external&&external.aborted))throw new Error('request aborted');
   if(!serviceUnavailable)delay=Math.min(delay*2,5000);
  }
 }
 function fail(){if(closed)return;status('failed');if(port)port.postMessage({t:'close'});close(true)}
-async function createSession(first){
+function knownCarrier(value){return value==='https'||value==='https-lanes'||value==='websocket'||value==='websocket-lanes'}
+function sessionEcho(response,expectedAttempt,states,exactAttempt){
+ const selected=response.headers.get('X-Carrier-Mode')||'',echo=response.headers.get('X-Carrier-Attempt')||'';
+ if(!knownCarrier(selected))throw new Error('invalid carrier mode');
+ if(!negotiationEnabled){if(echo!=='')throw new Error('unexpected carrier attempt');return {selected,state:''}}
+ const count=response.headers.get('X-Carrier-Candidate-Count')||'',deadline=response.headers.get('X-Carrier-Deadline')||'',state=response.headers.get('X-Carrier-State')||'';
+ if(!/^[1-4]$/.test(count)||!/^[1-9]\d*$/.test(deadline)||!states.includes(state))throw new Error('invalid carrier state');
+ const echoedAttempt=Number(echo),parsedCount=Number(count),parsedDeadline=Number(deadline);
+ if(!Number.isInteger(echoedAttempt)||echoedAttempt<1||(exactAttempt?echoedAttempt!==expectedAttempt:echoedAttempt>expectedAttempt))throw new Error('invalid carrier attempt');
+ if(parsedCount>candidateCount||parsedDeadline>candidateDeadlines[3])throw new Error('invalid carrier bounds');
+ if(!negotiatedFrozen){negotiatedCandidateCount=parsedCount;negotiatedFinalDeadline=parsedDeadline;negotiatedFrozen=true}
+ else if(parsedCount!==negotiatedCandidateCount||parsedDeadline!==negotiatedFinalDeadline)throw new Error('changed carrier bounds');
+ if(echoedAttempt>negotiatedCandidateCount)throw new Error('carrier attempt exceeds candidates');
+ return {selected,state};
+}
+function armCarrierDeadline(epoch){
+ if(!negotiationStartedAt||epoch!==attemptEpoch)return;
+ if(carrierTimer)clearTimeout(carrierTimer);
+ const deadline=carrierAttempt>=negotiatedCandidateCount?negotiatedFinalDeadline:candidateDeadlines[carrierAttempt-1];
+ const remaining=negotiationStartedAt+deadline*1000-Date.now();
+ carrierTimer=setTimeout(()=>advanceCarrier('timeout',epoch),Math.max(0,remaining));
+}
+function resetCandidate(){
+ if(pollController)pollController.abort();pollController=null;
+ if(socket){const previous=socket;socket=null;previous.close()}socketReady=false;
+ for(const lane of lanes.values()){if(lane.controller)lane.controller.abort();if(lane.socket)lane.socket.close()}
+ lanes.clear();closedLanes.clear();closedLaneOrder.length=0;upPending.length=0;upSequence=1;downCursor='0';upRunning=false;
+ sessionToken='';carrier='';candidateRunning=false;currentAttempt=null;
+}
+function advanceConfirmed(reason,epoch){
+ if(closed||carrierCommitted||epoch!==attemptEpoch)return;
+ resetCandidate();
+ if(carrierAttempt>=negotiatedCandidateCount||Date.now()>=negotiationStartedAt+negotiatedFinalDeadline*1000){switching=false;fail();return}
+ carrierAttempt++;carrierFailure=reason;attemptEpoch++;const nextEpoch=attemptEpoch;switching=false;
+ status('reconnecting');armCarrierDeadline(nextEpoch);createSession(nextEpoch);
+}
+function advanceCarrier(reason,epoch){
+ if(closed||carrierCommitted||epoch!==attemptEpoch||switching)return;
+ if(!negotiationEnabled){fail();return}
+ switching=true;if(carrierTimer)clearTimeout(carrierTimer);carrierTimer=null;
+ const snapshot=currentAttempt;if(attemptController)attemptController.abort();attemptController=null;
+ if(!snapshot||snapshot.epoch!==epoch){switching=false;fail();return}
+ resolveAttempt(reason,epoch,snapshot);
+}
+async function resolveAttempt(reason,epoch,snapshot){
+ const controller=new AbortController();attemptController=controller;
+ const remaining=negotiationStartedAt+negotiatedFinalDeadline*1000-Date.now();
+ if(remaining<=0){switching=false;fail();return}
+ const timer=setTimeout(()=>controller.abort(),remaining);
+ try{
+  const frozen=options('POST',bootstrap,snapshot.hello,attemptHeaders(snapshot.attempt,snapshot.failure),controller.signal);
+  const response=await request('/api/v1/session',frozen);
+  if(closed||epoch!==attemptEpoch){await response.arrayBuffer();return}
+  if(response.status===409){sessionEcho(response,snapshot.attempt,['committed','healthy'],false);await response.arrayBuffer();switching=false;fail();return}
+  if(response.status!==200){await response.arrayBuffer();switching=false;fail();return}
+  const echo=sessionEcho(response,snapshot.attempt,['provisional','committed','healthy'],true);
+  const token=response.headers.get('X-Session-Token')||'',cursor=response.headers.get('X-Down-Cursor')||'';
+  if(!token||cursor!=='0'||(snapshot.selected&&echo.selected!==snapshot.selected))throw new Error('changed carrier replay');
+  const welcome=await response.arrayBuffer();if(closed||epoch!==attemptEpoch)return;
+  cleanupToken=token;
+  if(!welcomeSent){welcomeSent=true;port.postMessage(welcome,[welcome])}
+  if(echo.state!=='provisional'){switching=false;fail();return}
+  advanceConfirmed(reason,epoch);
+ }catch(error){if(!closed&&epoch===attemptEpoch){switching=false;fail()}}
+ finally{clearTimeout(timer);if(attemptController===controller)attemptController=null}
+}
+function maybeStartCandidate(){
+ let probe;try{probe=findProbe()}catch(error){fail();return}
+ if(!probe||closed||carrierCommitted)return;
+ if(!sessionToken||candidateRunning)return;
+ candidateRunning=true;const epoch=attemptEpoch;
+ if(carrier==='https')probeHttp(probe,null,epoch);
+ else if(carrier==='https-lanes')probeHttp(probe,probe.id,epoch);
+ else if(carrier==='websocket')openCandidateSocket(probe,null,epoch);
+ else if(carrier==='websocket-lanes')openCandidateSocket(probe,probe.id,epoch);
+ else advanceCarrier('protocol',epoch);
+}
+async function createSession(epoch){
+ const controller=new AbortController(),attempt=carrierAttempt,failure=carrierFailure;
+ const snapshot={epoch,attempt,failure,hello:helloFrame,selected:''};currentAttempt=snapshot;attemptController=controller;
  try{
   status('connecting');
-  const response=await request('/api/v1/session',()=>options('POST',bootstrap,first));
-  if(response.status!==200||response.headers.get('X-Carrier-Mode')!==carrier)throw new Error('session creation rejected');
-  sessionToken=response.headers.get('X-Session-Token')||'';downCursor=response.headers.get('X-Down-Cursor')||'0';
-  if(!sessionToken)throw new Error('missing session token');
-  if(closed){deleteSession();return}
-  const welcome=await response.arrayBuffer();
-  port.postMessage(welcome,[welcome]);status('connected');
-  if(carrier==='https-lanes')ensureLane(0);
-  if(carrier==='websocket')openSocket();
+  const frozen=options('POST',bootstrap,snapshot.hello,attemptHeaders(attempt,failure),controller.signal);
+  const response=await request('/api/v1/session',frozen);
+  if(closed||epoch!==attemptEpoch){await response.arrayBuffer();return}
+  if(response.status===409){sessionEcho(response,attempt,['committed','healthy'],false);await response.arrayBuffer();fail();return}
+  if(response.status!==200){await response.arrayBuffer();advanceCarrier('http',epoch);return}
+  const echo=sessionEcho(response,attempt,['provisional'],true),selected=echo.selected;snapshot.selected=selected;
+  const token=response.headers.get('X-Session-Token')||'',cursor=response.headers.get('X-Down-Cursor')||'';
+  if(!token||cursor!=='0'){await response.arrayBuffer();advanceCarrier('protocol',epoch);return}
+  const welcome=await response.arrayBuffer();if(closed||epoch!==attemptEpoch)return;
+  carrier=selected;sessionToken=token;cleanupToken=token;downCursor=cursor;
+  if(!welcomeSent){welcomeSent=true;port.postMessage(welcome,[welcome])}
+  maybeStartCandidate();
+ }catch(error){if(closed||epoch!==attemptEpoch)return;advanceCarrier('network',epoch)}
+}
+async function probeHttp(probe,laneID,epoch){
+ try{
+  const headers={'X-Up-Seq':'1'},token=sessionToken,controller=attemptController,body=probe.data;if(laneID!==null)headers['X-Lane-ID']=String(laneID);
+  const response=await request('/api/v1/up',options('POST',token,body,headers,controller.signal));
+  if(closed||epoch!==attemptEpoch){await response.arrayBuffer();return}
+  if(response.status!==204){await response.arrayBuffer();advanceCarrier('http',epoch);return}
+  if(response.headers.get('X-Up-Ack')!=='1'){advanceCarrier('protocol',epoch);return}
+  if(laneID===null)upSequence=2;else ensureLane(laneID).sequence=2;
+  commitCarrier(probe,epoch);
+ }catch(error){if(!closed&&epoch===attemptEpoch)advanceCarrier('network',epoch)}
+}
+function commitCarrier(probe,epoch){
+ if(closed||carrierCommitted||epoch!==attemptEpoch)return;
+ if(switching){fail();return}
+ try{consumeProbe(probe)}catch(error){fail();return}
+ carrierCommitted=true;candidateRunning=false;if(carrierTimer)clearTimeout(carrierTimer);carrierTimer=null;
+ attemptController=null;currentAttempt=null;
+ status('connected');
+ if(carrier==='https')poll();
+ else if(carrier==='https-lanes'){const lane=lanes.get(probe.id);if(lane&&!lane.polling)pollLane(lane)}
  for(const data of pending.splice(0)){release(data.byteLength,1,null);queueCarrier(data)}
-  if(carrier==='https')poll();else if(carrier==='https-lanes')pollLane(lanes.get(0));
- }catch(error){fail()}
 }
 function queueCarrier(data){
  try{
@@ -174,22 +324,37 @@ async function runUp(){
  try{
   while(!closed&&sessionToken&&upPending.length){
    const batch=joinPending(upPending,null),sequence=String(upSequence);
-   const response=await request('/api/v1/up',()=>options('POST',sessionToken,batch.body,{'X-Up-Seq':sequence}));
+   const response=await request('/api/v1/up',options('POST',sessionToken,batch.body,{'X-Up-Seq':sequence}));
    if(response.status!==204||response.headers.get('X-Up-Ack')!==sequence)throw new Error('uplink rejected');
    release(batch.total,batch.count,null);port.postMessage({t:'traffic',up:batch.total,down:0});upSequence++;
   }
  }catch(error){fail()}
  finally{upRunning=false;if(!closed&&sessionToken&&upPending.length)runUp()}
 }
-function openSocket(){
- if(socket||closed)return;socket=new WebSocket(socketURL(),'tproxy-v1.'+sessionToken);socket.binaryType='arraybuffer';
- socket.onopen=()=>{if(closed)return;socketReady=true;status('connected');runSocketUp()};
- socket.onmessage=event=>{
-  if(closed||!(event.data instanceof ArrayBuffer)){fail();return}
-  try{const bound=frameBound(event.data,4096,batchLimit);if(bound.bytes!==event.data.byteLength)throw new Error('invalid frame batch')}catch(error){fail();return}
+function openCandidateSocket(probe,laneID,epoch){
+ const token=sessionToken,protocol=laneID===null?(negotiationEnabled?'tproxy-auto-v1.':'tproxy-v1.')+token:(negotiationEnabled?'tproxy-auto-lane-v1.':'tproxy-lane-v1.')+token+'.'+String(laneID);
+ const next=new WebSocket(socketURL(),protocol);next.binaryType='arraybuffer';let opened=false,lane=null;
+ if(laneID===null)socket=next;else{lane=ensureLane(laneID);lane.socket=next}
+ next.onopen=()=>{
+  if(closed||epoch!==attemptEpoch)return;opened=true;
+  if(lane){lane.ready=true}else socketReady=true;
+  try{next.send(probe.data);if(!negotiationEnabled)commitCarrier(probe,epoch)}catch(error){advanceCarrier('upgrade',epoch)}
+ };
+ next.onmessage=event=>{
+  if(closed||epoch!==attemptEpoch||!(event.data instanceof ArrayBuffer))return;
+  if(!carrierCommitted){if(event.data.byteLength!==0){advanceCarrier('protocol',epoch);return}commitCarrier(probe,epoch);return}
+  try{
+   if(lane){const values=splitFrames(event.data);for(const value of values)if(value.id!==lane.id)throw new Error('cross-lane frame');if(values.some(value=>value.type===3))lane.remoteClosed=true}
+   else{const bound=frameBound(event.data,4096,batchLimit);if(bound.bytes!==event.data.byteLength)throw new Error('invalid frame batch')}
+  }catch(error){if(lane)finishLane(lane,true);else fail();return}
   port.postMessage({t:'traffic',up:0,down:event.data.byteLength});port.postMessage(event.data,[event.data]);status('connected');
  };
- socket.onerror=()=>{};socket.onclose=()=>{socketReady=false;if(!closed)fail()};
+ next.onerror=()=>{};
+ next.onclose=()=>{
+  if(epoch!==attemptEpoch||closed)return;
+  if(!carrierCommitted){advanceCarrier(opened?'network':'upgrade',epoch);return}
+  if(lane){lane.ready=false;lane.socket=null;finishLane(lane,true)}else{socketReady=false;fail()}
+ };
 }
 function queueSocket(data){if(!reserve(data,null)){fail();return}upPending.push(data);runSocketUp()}
 async function waitSocket(next,size,limit){
@@ -210,7 +375,7 @@ async function poll(){
  while(!closed&&sessionToken){
   try{
    pollController=new AbortController();
-   const response=await request('/api/v1/down',()=>options('POST',sessionToken,null,{'X-Down-Cursor':downCursor},pollController.signal));
+   const response=await request('/api/v1/down',options('POST',sessionToken,null,{'X-Down-Cursor':downCursor},pollController.signal));
    if(response.status===204){status('connected');continue}
    if(response.status!==200)throw new Error('downlink rejected');
    const next=response.headers.get('X-Down-Cursor')||'',data=await response.arrayBuffer();
@@ -274,7 +439,7 @@ async function runLaneUp(lane){
  try{
   while(!closed&&sessionToken&&lane.pending.length){
    const batch=joinPending(lane.pending,lane),sequence=String(lane.sequence),laneID=String(lane.id);
-   const response=await request('/api/v1/up',()=>options('POST',sessionToken,batch.body,{'X-Up-Seq':sequence,'X-Lane-ID':laneID}));
+   const response=await request('/api/v1/up',options('POST',sessionToken,batch.body,{'X-Up-Seq':sequence,'X-Lane-ID':laneID}));
    if(response.status!==204||response.headers.get('X-Up-Ack')!==sequence)throw new Error('lane uplink rejected');
    release(batch.total,batch.count,lane);port.postMessage({t:'traffic',up:batch.total,down:0});lane.sequence++;
    if(!lane.polling)pollLane(lane);
@@ -287,7 +452,7 @@ async function pollLane(lane){
  try{
   while(!closed&&sessionToken&&lanes.get(lane.id)===lane){
    const controller=new AbortController(),laneID=String(lane.id);lane.controller=controller;
-   const response=await request('/api/v1/down',()=>options('POST',sessionToken,null,{'X-Down-Cursor':lane.cursor,'X-Lane-ID':laneID},controller.signal));
+   const response=await request('/api/v1/down',options('POST',sessionToken,null,{'X-Down-Cursor':lane.cursor,'X-Lane-ID':laneID},controller.signal));
    if(response.status===204){
     if(response.headers.get('X-Lane-Closed')==='1'){finishLane(lane,false);return}
     status('connected');continue;
@@ -303,10 +468,10 @@ async function pollLane(lane){
  finally{lane.polling=false;lane.controller=null}
 }
 function deleteSession(){
- if(sessionToken)fetch(relayOrigin+'/api/v1/session',options('DELETE',sessionToken,null,null,undefined,true)).catch(()=>{});
+ const token=cleanupToken||sessionToken;if(token)fetch(relayOrigin+'/api/v1/session',options('DELETE',token,null,null,undefined,true)).catch(()=>{});
 }
 function close(notifyServer){
- if(closed)return;closed=true;if(pollController)pollController.abort();
+ if(closed)return;closed=true;if(carrierTimer)clearTimeout(carrierTimer);if(attemptController)attemptController.abort();if(pollController)pollController.abort();
  if(socket)socket.close();for(const lane of lanes.values()){if(lane.controller)lane.controller.abort();if(lane.socket)lane.socket.close()}
  if(notifyServer)deleteSession();pending.length=0;upPending.length=0;
  for(const lane of lanes.values())lane.pending.length=0;lanes.clear();queuedBytes=0;queuedItems=0;if(port)port.close();
@@ -315,8 +480,8 @@ function activatePort(nextPort){
  initialized=true;port=nextPort;
  port.onmessage=message=>{
   if(message.data instanceof ArrayBuffer){
-   if(!createStarted){createStarted=true;createSession(message.data)}
-   else if(!sessionToken){if(!reserve(message.data,null)){fail();return}pending.push(message.data)}
+   if(!createStarted){createStarted=true;helloFrame=message.data;if(negotiationEnabled){negotiationStartedAt=Date.now();armCarrierDeadline(attemptEpoch)}createSession(attemptEpoch)}
+   else if(!carrierCommitted){if(!reserve(message.data,null)){fail();return}pending.push(message.data);maybeStartCandidate()}
    else queueCarrier(message.data);
   }else if(message.data&&message.data.t==='close')close(true);
  };
@@ -348,111 +513,6 @@ addEventListener('pagehide',()=>close(true),{once:true});
 </html>
 "##;
 
+// Rendered wire-contract tests remain separate from the embedded document.
 #[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn rendered_page_contains_no_template_markers_or_capability() {
-        let page = render(
-            "proxy.example.com",
-            "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",
-            2 * 1024 * 1024,
-            32 * 1024 * 1024,
-            16 * 1024,
-            WebCarrier::HttpsLanes,
-            &SecureRandom::new(),
-        );
-        assert!(!page.body.contains("__"));
-        assert!(!page.body.contains("bridge="));
-        assert!(page.body.contains("X-Up-Seq"));
-        assert!(page.body.contains("carrier='https-lanes'"));
-        assert!(page.body.contains("X-Lane-ID"));
-        assert!(page.body.contains("const when=Date.parse(header)"));
-        assert!(page.body.contains("},{once:false});"));
-        assert!(
-            page.body
-                .contains("if(!sessionToken)throw new Error('missing session token')")
-        );
-        assert!(!page.body.contains("welcomeBytes"));
-        assert!(
-            page.body
-                .contains("for(const value of splitFrames(data))if(value.id!==lane.id)")
-        );
-        assert!(
-            page.body
-                .contains("let frames;try{frames=splitFrames(value)}catch(error){fail();return}")
-        );
-        assert!(
-            page.content_security_policy
-                .contains("frame-ancestors http://127.0.0.1:*")
-        );
-    }
-
-    #[test]
-    fn rendered_page_is_parseable_by_ios_native_carrier() {
-        let bootstrap = "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB";
-        let page = render(
-            "proxy.example.com",
-            bootstrap,
-            2 * 1024 * 1024,
-            32 * 1024 * 1024,
-            16 * 1024,
-            WebCarrier::Https,
-            &SecureRandom::new(),
-        );
-        let accepted_shapes = [
-            format!("const bootstrap=\"{bootstrap}\""),
-            format!("const bootstrap='{bootstrap}'"),
-            format!("bootstrap=\"{bootstrap}\""),
-        ];
-
-        assert!(
-            accepted_shapes
-                .iter()
-                .any(|shape| page.body.contains(shape)),
-            "the iOS native carrier cannot parse a comma-declared single-quoted bootstrap"
-        );
-    }
-
-    #[test]
-    fn rendered_page_advertises_exact_websocket_carriers() {
-        let websocket = render(
-            "proxy.example.com",
-            "CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC",
-            2 * 1024 * 1024,
-            32 * 1024 * 1024,
-            16 * 1024,
-            WebCarrier::Websocket,
-            &SecureRandom::new(),
-        );
-        assert!(websocket.body.contains("carrier='websocket'"));
-        assert!(
-            websocket
-                .body
-                .contains("new WebSocket(socketURL(),'tproxy-v1.'+sessionToken)")
-        );
-        assert!(
-            websocket
-                .content_security_policy
-                .contains("connect-src 'self' wss://proxy.example.com")
-        );
-
-        let lanes = render(
-            "proxy.example.com",
-            "DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD",
-            2 * 1024 * 1024,
-            32 * 1024 * 1024,
-            16 * 1024,
-            WebCarrier::WebsocketLanes,
-            &SecureRandom::new(),
-        );
-        assert!(lanes.body.contains("carrier='websocket-lanes'"));
-        assert!(
-            lanes
-                .body
-                .contains("'tproxy-lane-v1.'+sessionToken+'.'+String(lane.id)")
-        );
-        assert!(!lanes.body.contains("__"));
-    }
-}
+mod tests;

src/web/bridge/tests.rs

@@ -0,0 +1,110 @@
+use super::*;
+
+fn render_page(bootstrap: &str, candidate_count: usize) -> BridgePage {
+    render(
+        "proxy.example.com",
+        bootstrap,
+        2 * 1024 * 1024,
+        32 * 1024 * 1024,
+        16 * 1024,
+        true,
+        candidate_count,
+        [3, 5, 8, 12],
+        &SecureRandom::new(),
+    )
+}
+
+#[test]
+fn rendered_page_contains_bounded_negotiation_contract() {
+    let page = render_page("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA", 4);
+    assert!(!page.body.contains("__"));
+    assert!(!page.body.contains("bridge="));
+    assert!(page.body.contains("X-Carrier-Capabilities"));
+    assert!(page.body.contains("X-Carrier-Attempt"));
+    assert!(page.body.contains("candidateCount=4"));
+    assert!(page.body.contains("candidateDeadlines=[3,5,8,12]"));
+    assert!(page.body.contains("X-Up-Seq"));
+    assert!(page.body.contains("X-Lane-ID"));
+    assert!(page.body.contains("tproxy-auto-v1."));
+    assert!(page.body.contains("tproxy-auto-lane-v1."));
+    assert!(
+        page.content_security_policy
+            .contains("frame-ancestors http://127.0.0.1:*")
+    );
+}
+
+#[test]
+fn rendered_page_preserves_the_ios_bootstrap_literal() {
+    let bootstrap = "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB";
+    let page = render_page(bootstrap, 2);
+    assert!(
+        page.body
+            .contains(&format!("const bootstrap=\"{bootstrap}\""))
+    );
+}
+
+#[test]
+fn effective_deadline_formula_uses_the_final_checkpoint() {
+    let page = render_page("CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC", 3);
+    assert!(
+        page.body
+            .contains("negotiatedFinalDeadline=candidateDeadlines[3]")
+    );
+    assert!(
+        page.body
+            .contains("carrierAttempt>=negotiatedCandidateCount?negotiatedFinalDeadline")
+    );
+}
+
+#[test]
+fn disabled_negotiation_does_not_arm_a_carrier_deadline() {
+    let page = render(
+        "proxy.example.com",
+        "DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD",
+        2 * 1024 * 1024,
+        32 * 1024 * 1024,
+        16 * 1024,
+        false,
+        1,
+        [3, 5, 8, 12],
+        &SecureRandom::new(),
+    );
+    assert!(page.body.contains(
+        "if(negotiationEnabled){negotiationStartedAt=Date.now();armCarrierDeadline(attemptEpoch)}"
+    ));
+    assert!(
+        page.body
+            .contains("negotiationEnabled?'tproxy-auto-v1.':'tproxy-v1.'")
+    );
+}
+
+#[test]
+fn retry_and_attempt_state_are_frozen_before_fetch() {
+    let page = render_page("EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE", 4);
+    assert!(
+        page.body
+            .contains("async function request(path,frozenOptions)")
+    );
+    assert!(!page.body.contains("makeOptions"));
+    assert!(
+        page.body
+            .contains("if(closed||(external&&external.aborted))throw new Error('request aborted')")
+    );
+    assert!(page.body.contains(
+        "const frozen=options('POST',bootstrap,snapshot.hello,attemptHeaders(snapshot.attempt,snapshot.failure),controller.signal)"
+    ));
+}
+
+#[test]
+fn ambiguous_commit_is_resolved_before_carrier_advance() {
+    let page = render_page("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", 4);
+    assert!(page.body.contains("resolveAttempt(reason,epoch,snapshot)"));
+    assert!(page.body.contains(
+        "sessionEcho(response,snapshot.attempt,['provisional','committed','healthy'],true)"
+    ));
+    assert!(
+        page.body
+            .contains("if(echo.state!=='provisional'){switching=false;fail();return}")
+    );
+    assert!(page.body.contains("const token=cleanupToken||sessionToken"));
+}

src/web/http.rs

@@ -1,6 +1,6 @@
 use std::convert::Infallible;
 use std::error::Error;
-use std::net::{IpAddr, SocketAddr};
+use std::net::SocketAddr;
 use std::sync::Arc;
 use std::time::{Duration, Instant};
 
@@ -19,7 +19,6 @@ use tokio_util::sync::CancellationToken;
 
 use crate::config::{WebClientIpSource, WebRuntimeVhost};
 use crate::web::bridge;
-use crate::web::frame::{self, FrameType};
 use crate::web::manager::{ManagerError, WebProcessRuntime};
 
 // Response-body activity keeps connection idle accounting lifecycle-correct.
@@ -34,6 +33,8 @@ mod down;
 mod request;
 // Carrier response construction and lane-header helpers are shared by handlers.
 mod response;
+// Session creation and replacement negotiation remain separate from request routing.
+mod session;
 // RFC 6455 upgrade validation and carrier drivers remain isolated from HTTP routing.
 #[cfg(test)]
 mod tests;
@@ -56,12 +57,12 @@ use response::{
     bad_gateway, carrier_empty, carrier_headers, carrier_lane, full_response, generic_not_found,
     insert_header, service_unavailable,
 };
+use session::handle_session;
 
 type BoxError = Box<dyn Error + Send + Sync>;
 type HttpBody = UnsyncBoxBody<Bytes, BoxError>;
 type HttpResponse = Response<HttpBody>;
 
-const CREATE_BODY_LIMIT: usize = 64;
 const TRANSPORT_PATHS: [&str; 3] = ["/api/v1/session", "/api/v1/up", "/api/v1/down"];
 const WEBSOCKET_PATH: &str = "/api/v1/ws";
 
@@ -224,7 +225,6 @@ async fn handle_root(
         trace.set_route(TraceRoute::Bridge);
         trace.set_effective_ip(client_ip);
     }
-    let carrier = profile.carrier;
     let bootstrap = match runtime.issue_bootstrap(Arc::clone(&profile), client_ip) {
         Ok(bootstrap) => bootstrap,
         Err(error) => {
@@ -234,7 +234,7 @@ async fn handle_root(
                 &profile,
                 TraceLifecycleEvent::BootstrapRejected,
                 None,
-                Some(manager_error_reason(error)),
+                Some(error.as_str()),
             );
             strip_query(&mut request);
             return serve_decoy(request, vhost, true, &runtime).await;
@@ -251,7 +251,9 @@ async fn handle_root(
         generation.config().web.limits.carrier_batch_bytes,
         generation.config().web.limits.pending_bytes_per_session,
         generation.config().web.limits.pending_items_per_session,
-        carrier,
+        profile.carrier_negotiation_enabled,
+        profile.carriers.len(),
+        profile.carrier_negotiation_deadlines_secs,
         &generation.rng,
     );
     let mut response = full_response(StatusCode::OK, Bytes::from(page.body));
@@ -315,127 +317,6 @@ async fn handle_api(
     }
 }
 
-async fn handle_session(
-    request: Request<RequestBody>,
-    runtime: Arc<WebProcessRuntime>,
-    vhost: Arc<WebRuntimeVhost>,
-    token_hash: crate::web::manager::TokenHash,
-    client_ip: IpAddr,
-) -> HttpResponse {
-    if request.headers().contains_key("x-lane-id") {
-        return serve_decoy(request, vhost, true, &runtime).await;
-    }
-    if request.method() == Method::DELETE {
-        if request.headers().contains_key(header::CONTENT_TYPE) {
-            return serve_decoy(request, vhost, true, &runtime).await;
-        }
-        if let Some(trace) = request_trace(&request)
-            && let Ok(session) = runtime.get_session(token_hash, &vhost.host)
-        {
-            trace.set_route(TraceRoute::Session);
-            trace.bind_identity(session.trace_identity());
-        }
-        let CollectedBody {
-            request,
-            body,
-            _body_budget,
-        } = match collect_body(request, &runtime, 1, true).await {
-            Ok(result) => result,
-            Err(CollectBodyError::Limit) => return service_unavailable(),
-            Err(CollectBodyError::Invalid(request)) => {
-                return serve_decoy(request, vhost, true, &runtime).await;
-            }
-        };
-        if !body.is_empty() || runtime.close_token(token_hash, &vhost.host).is_err() {
-            return serve_decoy(request, vhost, true, &runtime).await;
-        }
-        return carrier_empty(StatusCode::NO_CONTENT);
-    }
-    if request.method() != Method::POST || !binary_content_type(&request) {
-        return serve_decoy(request, vhost, true, &runtime).await;
-    }
-    let Some((trace_session_id, profile)) =
-        runtime.bootstrap_trace_identity(token_hash, &vhost.host)
-    else {
-        return serve_decoy(request, vhost, true, &runtime).await;
-    };
-    if let Some(trace) = request_trace(&request) {
-        trace.set_route(TraceRoute::Session);
-        trace.bind_profile(&profile, trace_session_id);
-    }
-    let CollectedBody {
-        request,
-        body,
-        _body_budget,
-    } = match collect_body(request, &runtime, CREATE_BODY_LIMIT, false).await {
-        Ok(result) => result,
-        Err(CollectBodyError::Limit) => return service_unavailable(),
-        Err(CollectBodyError::Invalid(request)) => {
-            return serve_decoy(request, vhost, true, &runtime).await;
-        }
-    };
-    if let Some(trace) = request_trace(&request) {
-        trace.record_frames(
-            TraceDirection::Request,
-            &body,
-            &runtime.active_generation().config().web.limits,
-        );
-    }
-    match runtime.create_session(token_hash, &vhost.host, client_ip, &body) {
-        Ok(result) => {
-            let welcome = frame::encode(FrameType::Welcome, 0, &[]);
-            if let Some(trace) = request_trace(&request) {
-                trace.register_redaction(result.token.as_bytes());
-                trace.record_frames(
-                    TraceDirection::Response,
-                    &welcome,
-                    &runtime.active_generation().config().web.limits,
-                );
-            }
-            let mut response = full_response(StatusCode::OK, welcome);
-            carrier_headers(&mut response);
-            insert_header(
-                &mut response,
-                HeaderName::from_static("x-session-token"),
-                &result.token,
-            );
-            response.headers_mut().insert(
-                HeaderName::from_static("x-carrier-mode"),
-                HeaderValue::from_static(result.carrier.as_str()),
-            );
-            response.headers_mut().insert(
-                HeaderName::from_static("x-down-cursor"),
-                HeaderValue::from_static("0"),
-            );
-            response
-        }
-        Err(
-            error @ (ManagerError::Limit | ManagerError::Backpressure | ManagerError::Concurrent),
-        ) => {
-            runtime.trace().record_profile_lifecycle(
-                client_ip,
-                Some(trace_session_id),
-                &profile,
-                TraceLifecycleEvent::SessionRejected,
-                None,
-                Some(manager_error_reason(error)),
-            );
-            service_unavailable()
-        }
-        Err(error) => {
-            runtime.trace().record_profile_lifecycle(
-                client_ip,
-                Some(trace_session_id),
-                &profile,
-                TraceLifecycleEvent::SessionRejected,
-                None,
-                Some(manager_error_reason(error)),
-            );
-            serve_decoy(request, vhost, true, &runtime).await
-        }
-    }
-}
-
 async fn handle_up(
     request: Request<RequestBody>,
     runtime: Arc<WebProcessRuntime>,
@@ -462,12 +343,7 @@ async fn handle_up(
     let Some(lane_id) = carrier_lane(&request, session.carrier()) else {
         return serve_decoy(request, vhost, true, &runtime).await;
     };
-    let limit = runtime
-        .active_generation()
-        .config()
-        .web
-        .limits
-        .max_body_bytes;
+    let limit = session.limits().max_body_bytes;
     let CollectedBody {
         request,
         body,
@@ -480,11 +356,7 @@ async fn handle_up(
         }
     };
     if let Some(trace) = request_trace(&request) {
-        trace.record_frames(
-            TraceDirection::Request,
-            &body,
-            &runtime.active_generation().config().web.limits,
-        );
+        trace.record_frames(TraceDirection::Request, &body, session.limits());
     }
     let result = match lane_id {
         Some(lane_id) => session.process_up_lane(lane_id, sequence, &body),
@@ -524,14 +396,3 @@ fn set_trace_route<B>(request: &Request<B>, route: TraceRoute) {
         trace.set_route(route);
     }
 }
-
-fn manager_error_reason(error: ManagerError) -> &'static str {
-    match error {
-        ManagerError::Authentication => "authentication",
-        ManagerError::Backpressure => "backpressure",
-        ManagerError::Limit => "limit",
-        ManagerError::Protocol => "protocol",
-        ManagerError::Concurrent => "concurrent",
-        ManagerError::Closed => "closed",
-    }
-}

src/web/http/down.rs

@@ -56,8 +56,11 @@ pub(super) async fn handle_down(
     if !body.is_empty() {
         return serve_decoy(request, vhost, true, &runtime).await;
     }
-    let _lane_poll = if lane_id.is_some() {
-        let Some(permit) = runtime.try_lane_poll() else {
+    let Some(_down_poll) = runtime.try_lane_poll(false) else {
+        return service_unavailable();
+    };
+    let _control_lane_poll = if lane_id == Some(0) {
+        let Some(permit) = runtime.try_lane_poll(true) else {
             return service_unavailable();
         };
         Some(permit)
@@ -86,11 +89,7 @@ pub(super) async fn handle_down(
         }
         Ok(result) => {
             if let Some(trace) = request_trace(&request) {
-                trace.record_frames(
-                    TraceDirection::Response,
-                    &result.body,
-                    &runtime.active_generation().config().web.limits,
-                );
+                trace.record_frames(TraceDirection::Response, &result.body, session.limits());
             }
             let mut response = full_response(StatusCode::OK, result.body);
             carrier_headers(&mut response);

src/web/http/legacy_tests.rs

@@ -0,0 +1,99 @@
+use super::*;
+
+#[tokio::test]
+async fn windows_restricted_webview_empty_cookie_preserves_the_carrier_flow() {
+    for (index, carrier) in [WebCarrier::Https, WebCarrier::HttpsLanes]
+        .into_iter()
+        .enumerate()
+    {
+        let capability = [12 + index as u8; 32];
+        let mut config = runtime_config(capability, carrier);
+        config.web.timeouts.long_poll_secs = 0;
+        let generation = test_runtime_generation(1, config);
+        let active_runtime = Arc::new(ArcSwap::from(Arc::clone(&generation)));
+        let runtime = WebProcessRuntime::start(active_runtime);
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let encoded = base64::engine::general_purpose::URL_SAFE_NO_PAD.encode(capability);
+        let root = format!(
+            "GET /?bridge={encoded} HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nCookie:\r\nConnection: close\r\n\r\n"
+        )
+        .into_bytes();
+        let root_response = request(&listener, &runtime, root).await;
+        let (root_headers, root_body) = split_response(&root_response);
+        assert!(root_headers.starts_with(b"HTTP/1.1 200"));
+        let root_body = std::str::from_utf8(root_body).unwrap();
+        let bootstrap = root_body
+            .split_once("bootstrap=\"")
+            .and_then(|(_, suffix)| suffix.split_once('"'))
+            .map(|(token, _)| token)
+            .unwrap();
+
+        let hello = frame::encode(FrameType::Hello, 0, &[1]);
+        let create = |cookie: &str| {
+            let mut request = format!(
+                "POST /api/v1/session HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {bootstrap}\r\nContent-Type: application/octet-stream\r\n{cookie}Content-Length: {}\r\nConnection: close\r\n\r\n",
+                hello.len()
+            )
+            .into_bytes();
+            request.extend_from_slice(&hello);
+            request
+        };
+        let nonempty_cookie =
+            request(&listener, &runtime, create("Cookie: state=unexpected\r\n")).await;
+        assert!(!nonempty_cookie.starts_with(b"HTTP/1.1 200"));
+        let duplicate_cookie = request(
+            &listener,
+            &runtime,
+            create("Cookie:\r\nCookie: state=unexpected\r\n"),
+        )
+        .await;
+        assert!(!duplicate_cookie.starts_with(b"HTTP/1.1 200"));
+
+        let create_response = request(&listener, &runtime, create("Cookie:\r\n")).await;
+        let (create_headers, create_body) = split_response(&create_response);
+        assert!(create_headers.starts_with(b"HTTP/1.1 200"));
+        assert_eq!(
+            response_header(create_headers, "x-carrier-mode"),
+            carrier.as_str()
+        );
+        assert_eq!(create_body, frame::encode(FrameType::Welcome, 0, &[]));
+        let session = response_header(create_headers, "x-session-token").to_string();
+        let lane = if carrier == WebCarrier::HttpsLanes {
+            "X-Lane-ID: 0\r\n"
+        } else {
+            ""
+        };
+
+        let pong = frame::encode(FrameType::Pong, 0, &[]);
+        let mut uplink = format!(
+            "POST /api/v1/up HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {session}\r\nContent-Type: application/octet-stream\r\nCookie:\r\nX-Up-Seq: 1\r\n{lane}Content-Length: {}\r\nConnection: close\r\n\r\n",
+            pong.len()
+        )
+        .into_bytes();
+        uplink.extend_from_slice(&pong);
+        let uplink_response = request(&listener, &runtime, uplink).await;
+        let (uplink_headers, _) = split_response(&uplink_response);
+        assert!(uplink_headers.starts_with(b"HTTP/1.1 204"));
+        assert_eq!(response_header(uplink_headers, "x-up-ack"), "1");
+
+        let downlink = format!(
+            "POST /api/v1/down HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {session}\r\nCookie:\r\nX-Down-Cursor: 0\r\n{lane}Content-Length: 0\r\nConnection: close\r\n\r\n"
+        )
+        .into_bytes();
+        let downlink_response = request(&listener, &runtime, downlink).await;
+        let (downlink_headers, _) = split_response(&downlink_response);
+        assert!(downlink_headers.starts_with(b"HTTP/1.1 204"));
+        assert_eq!(response_header(downlink_headers, "x-down-cursor"), "0");
+
+        let close = format!(
+            "DELETE /api/v1/session HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {session}\r\nCookie:\r\nContent-Length: 0\r\nConnection: close\r\n\r\n"
+        )
+        .into_bytes();
+        let close_response = request(&listener, &runtime, close).await;
+        assert!(close_response.starts_with(b"HTTP/1.1 204"));
+
+        runtime.shutdown().await;
+        generation.stop_sessions().await;
+        generation.stop_background_tasks().await;
+    }
+}

src/web/http/negotiation_tests.rs

@@ -0,0 +1,488 @@
+use super::*;
+
+use std::time::Duration;
+
+use sha2::{Digest, Sha256};
+
+const CAPABILITIES: &str = "https,https-lanes,websocket,websocket-lanes";
+const NATIVE_USER_AGENT_HEADER: &str =
+    "User-Agent: Telegram/3951 CFNetwork/3896.100.1.2.1 Darwin/27.0.0\r\n";
+
+fn issue_bootstrap(runtime: &Arc<WebProcessRuntime>, client_ip: &str) -> String {
+    let profile = runtime
+        .active_generation()
+        .config()
+        .web
+        .runtime
+        .as_ref()
+        .unwrap()
+        .profiles[0]
+        .clone();
+    runtime
+        .issue_bootstrap(profile, client_ip.parse().unwrap())
+        .unwrap()
+        .token
+}
+
+fn create_request(
+    bootstrap: &str,
+    hello: &[u8],
+    attempt: Option<u8>,
+    failure: Option<&str>,
+) -> Vec<u8> {
+    create_request_with_headers(bootstrap, hello, attempt, failure, "")
+}
+
+fn create_request_with_headers(
+    bootstrap: &str,
+    hello: &[u8],
+    attempt: Option<u8>,
+    failure: Option<&str>,
+    extra_headers: &str,
+) -> Vec<u8> {
+    let negotiation = attempt.map_or_else(String::new, |attempt| {
+        let failure = failure
+            .map(|failure| format!("X-Carrier-Failure: {failure}\r\n"))
+            .unwrap_or_default();
+        format!(
+            "X-Carrier-Capabilities: {CAPABILITIES}\r\nX-Carrier-Attempt: {attempt}\r\n{failure}"
+        )
+    });
+    let mut request = format!(
+        "POST /api/v1/session HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {bootstrap}\r\nContent-Type: application/octet-stream\r\n{negotiation}{extra_headers}Content-Length: {}\r\nConnection: close\r\n\r\n",
+        hello.len()
+    )
+    .into_bytes();
+    request.extend_from_slice(hello);
+    request
+}
+
+fn optional_response_header<'a>(headers: &'a [u8], name: &str) -> Option<&'a str> {
+    std::str::from_utf8(headers)
+        .unwrap()
+        .lines()
+        .filter_map(|line| line.split_once(':'))
+        .find_map(|(header, value)| header.eq_ignore_ascii_case(name).then_some(value.trim()))
+}
+
+fn token_hash(token: &str) -> crate::web::manager::TokenHash {
+    let raw = base64::engine::general_purpose::URL_SAFE_NO_PAD
+        .decode(token)
+        .unwrap();
+    Sha256::digest(raw).into()
+}
+
+fn assert_no_negotiation_headers(headers: &[u8]) {
+    for header in [
+        "x-carrier-attempt",
+        "x-carrier-candidate-count",
+        "x-carrier-deadline",
+        "x-carrier-state",
+    ] {
+        assert!(optional_response_header(headers, header).is_none());
+    }
+}
+
+#[tokio::test]
+async fn absent_carriers_reject_negotiation_and_preserve_legacy_creation() {
+    let capability = [41; 32];
+    let generation = test_runtime_generation(1, runtime_config(capability, WebCarrier::Https));
+    let runtime = WebProcessRuntime::start(Arc::new(ArcSwap::from(Arc::clone(&generation))));
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let bootstrap = issue_bootstrap(&runtime, "192.0.2.10");
+    let hello = frame::encode(FrameType::Hello, 0, &[1]);
+
+    let rejected = request(
+        &listener,
+        &runtime,
+        create_request(&bootstrap, &hello, Some(1), None),
+    )
+    .await;
+    let (rejected_headers, _) = split_response(&rejected);
+    assert!(optional_response_header(rejected_headers, "x-session-token").is_none());
+
+    let legacy = request(
+        &listener,
+        &runtime,
+        create_request(&bootstrap, &hello, None, None),
+    )
+    .await;
+    let (legacy_headers, _) = split_response(&legacy);
+    assert!(legacy_headers.starts_with(b"HTTP/1.1 200"));
+    assert_eq!(response_header(legacy_headers, "x-carrier-mode"), "https");
+    assert!(optional_response_header(legacy_headers, "x-carrier-attempt").is_none());
+
+    runtime.shutdown().await;
+    generation.stop_sessions().await;
+    generation.stop_background_tasks().await;
+}
+
+#[tokio::test]
+async fn metadata_free_native_client_can_use_each_fixed_carrier() {
+    for (index, carrier) in WebCarrier::ALL.into_iter().enumerate() {
+        let capability = [50 + index as u8; 32];
+        let generation = test_runtime_generation(1, runtime_config(capability, carrier));
+        let runtime = WebProcessRuntime::start(Arc::new(ArcSwap::from(Arc::clone(&generation))));
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let bootstrap = issue_bootstrap(&runtime, "192.0.2.10");
+        let hello = frame::encode(FrameType::Hello, 0, &[1]);
+
+        let response = request(
+            &listener,
+            &runtime,
+            create_request_with_headers(&bootstrap, &hello, None, None, NATIVE_USER_AGENT_HEADER),
+        )
+        .await;
+        let (headers, _) = split_response(&response);
+        assert!(headers.starts_with(b"HTTP/1.1 200"));
+        assert_eq!(response_header(headers, "x-carrier-mode"), carrier.as_str());
+        assert_no_negotiation_headers(headers);
+
+        runtime.shutdown().await;
+        generation.stop_sessions().await;
+        generation.stop_background_tasks().await;
+    }
+}
+
+#[tokio::test]
+async fn metadata_free_native_client_uses_fallback_when_candidates_are_enabled() {
+    let capability = [55; 32];
+    let generation = test_runtime_generation(
+        1,
+        negotiation_runtime_config(
+            capability,
+            WebCarrier::HttpsLanes,
+            false,
+            Arc::from([WebCarrier::Websocket, WebCarrier::HttpsLanes]),
+        ),
+    );
+    let runtime = WebProcessRuntime::start(Arc::new(ArcSwap::from(Arc::clone(&generation))));
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let bootstrap = issue_bootstrap(&runtime, "192.0.2.10");
+    let hello = frame::encode(FrameType::Hello, 0, &[1]);
+
+    let response = request(
+        &listener,
+        &runtime,
+        create_request_with_headers(&bootstrap, &hello, None, None, NATIVE_USER_AGENT_HEADER),
+    )
+    .await;
+    let (headers, _) = split_response(&response);
+    assert!(headers.starts_with(b"HTTP/1.1 200"));
+    assert_eq!(response_header(headers, "x-carrier-mode"), "https-lanes");
+    assert_no_negotiation_headers(headers);
+
+    runtime.shutdown().await;
+    generation.stop_sessions().await;
+    generation.stop_background_tasks().await;
+}
+
+#[tokio::test]
+async fn explicit_native_capabilities_participate_in_automatic_selection() {
+    let capability = [56; 32];
+    let generation = test_runtime_generation(
+        1,
+        negotiation_runtime_config(
+            capability,
+            WebCarrier::Https,
+            false,
+            Arc::from([WebCarrier::WebsocketLanes, WebCarrier::Https]),
+        ),
+    );
+    let runtime = WebProcessRuntime::start(Arc::new(ArcSwap::from(Arc::clone(&generation))));
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let bootstrap = issue_bootstrap(&runtime, "192.0.2.10");
+    let hello = frame::encode(FrameType::Hello, 0, &[1]);
+
+    let response = request(
+        &listener,
+        &runtime,
+        create_request_with_headers(&bootstrap, &hello, Some(1), None, NATIVE_USER_AGENT_HEADER),
+    )
+    .await;
+    let (headers, _) = split_response(&response);
+    assert!(headers.starts_with(b"HTTP/1.1 200"));
+    assert_eq!(
+        response_header(headers, "x-carrier-mode"),
+        "websocket-lanes"
+    );
+    assert_eq!(response_header(headers, "x-carrier-attempt"), "1");
+    assert_eq!(response_header(headers, "x-carrier-candidate-count"), "2");
+
+    runtime.shutdown().await;
+    generation.stop_sessions().await;
+    generation.stop_background_tasks().await;
+}
+
+#[tokio::test]
+async fn negotiation_replays_replaces_and_freezes_after_carrier_commit() {
+    let capability = [42; 32];
+    let mut config = negotiation_runtime_config(
+        capability,
+        WebCarrier::Websocket,
+        false,
+        Arc::from([
+            WebCarrier::Https,
+            WebCarrier::HttpsLanes,
+            WebCarrier::Websocket,
+        ]),
+    );
+    config.web.timeouts.long_poll_secs = 1;
+    let generation = test_runtime_generation(1, config);
+    let runtime = WebProcessRuntime::start(Arc::new(ArcSwap::from(Arc::clone(&generation))));
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let bootstrap = issue_bootstrap(&runtime, "192.0.2.10");
+    let hello = frame::encode(FrameType::Hello, 0, &[1]);
+
+    let first_request = create_request(&bootstrap, &hello, Some(1), None);
+    let first = request(&listener, &runtime, first_request.clone()).await;
+    let (first_headers, _) = split_response(&first);
+    assert_eq!(response_header(first_headers, "x-carrier-mode"), "https");
+    assert_eq!(response_header(first_headers, "x-carrier-attempt"), "1");
+    let first_token = response_header(first_headers, "x-session-token").to_string();
+
+    let replay = request(&listener, &runtime, first_request).await;
+    let (replay_headers, _) = split_response(&replay);
+    assert_eq!(
+        response_header(replay_headers, "x-session-token"),
+        first_token
+    );
+    assert_eq!(
+        response_header(replay_headers, "x-carrier-candidate-count"),
+        "3"
+    );
+    assert_eq!(
+        response_header(replay_headers, "x-carrier-state"),
+        "provisional"
+    );
+
+    let second_request = create_request(&bootstrap, &hello, Some(2), Some("timeout"));
+    let second = request(&listener, &runtime, second_request.clone()).await;
+    let (second_headers, _) = split_response(&second);
+    assert_eq!(
+        response_header(second_headers, "x-carrier-mode"),
+        "https-lanes"
+    );
+    assert_eq!(response_header(second_headers, "x-carrier-attempt"), "2");
+    let second_token = response_header(second_headers, "x-session-token").to_string();
+    assert_ne!(first_token, second_token);
+    assert!(
+        runtime
+            .get_session(token_hash(&first_token), "proxy.example.com")
+            .is_err()
+    );
+
+    let second_replay = request(&listener, &runtime, second_request).await;
+    let (second_replay_headers, _) = split_response(&second_replay);
+    for header in [
+        "x-session-token",
+        "x-carrier-mode",
+        "x-carrier-attempt",
+        "x-carrier-candidate-count",
+        "x-carrier-deadline",
+        "x-carrier-state",
+    ] {
+        assert_eq!(
+            response_header(second_replay_headers, header),
+            response_header(second_headers, header),
+        );
+    }
+
+    let changed_failure = request(
+        &listener,
+        &runtime,
+        create_request(&bootstrap, &hello, Some(2), Some("network")),
+    )
+    .await;
+    let (changed_failure_headers, _) = split_response(&changed_failure);
+    assert!(optional_response_header(changed_failure_headers, "x-session-token").is_none());
+
+    let open = frame::encode(FrameType::Open, 7, &[]);
+    let data = frame::encode(FrameType::Data, 7, &[0]);
+    let mut body = Vec::with_capacity(open.len() + data.len());
+    body.extend_from_slice(&open);
+    body.extend_from_slice(&data);
+    let mut uplink = format!(
+        "POST /api/v1/up HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {second_token}\r\nContent-Type: application/octet-stream\r\nX-Up-Seq: 1\r\nX-Lane-ID: 7\r\nContent-Length: {}\r\nConnection: close\r\n\r\n",
+        body.len()
+    )
+    .into_bytes();
+    uplink.extend_from_slice(&body);
+    let accepted = request(&listener, &runtime, uplink).await;
+    assert!(accepted.starts_with(b"HTTP/1.1 204"));
+
+    let first_down = format!(
+        "POST /api/v1/down HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {second_token}\r\nX-Down-Cursor: 0\r\nX-Lane-ID: 7\r\nContent-Length: 0\r\nConnection: close\r\n\r\n"
+    )
+    .into_bytes();
+    let first_down = request(&listener, &runtime, first_down).await;
+    let (first_down_headers, first_down_body) = split_response(&first_down);
+    assert!(first_down_headers.starts_with(b"HTTP/1.1 200"));
+    assert!(!first_down_body.is_empty());
+    assert_eq!(response_header(first_down_headers, "x-down-cursor"), "1");
+
+    let acknowledgement = format!(
+        "POST /api/v1/down HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {second_token}\r\nX-Down-Cursor: 1\r\nX-Lane-ID: 7\r\nContent-Length: 0\r\nConnection: close\r\n\r\n"
+    )
+    .into_bytes();
+    let acknowledgement = request(&listener, &runtime, acknowledgement).await;
+    assert!(acknowledgement.starts_with(b"HTTP/1.1 204"));
+
+    let third = request(
+        &listener,
+        &runtime,
+        create_request(&bootstrap, &hello, Some(3), Some("http")),
+    )
+    .await;
+    let (third_headers, _) = split_response(&third);
+    assert!(third_headers.starts_with(b"HTTP/1.1 409"));
+    assert!(optional_response_header(third_headers, "x-session-token").is_none());
+    assert_eq!(
+        response_header(third_headers, "x-carrier-mode"),
+        "https-lanes"
+    );
+    assert_eq!(response_header(third_headers, "x-carrier-attempt"), "2");
+    assert_eq!(
+        response_header(third_headers, "x-carrier-candidate-count"),
+        "3"
+    );
+    assert_eq!(response_header(third_headers, "x-carrier-deadline"), "12");
+    assert_eq!(
+        response_header(third_headers, "x-carrier-state"),
+        "committed"
+    );
+    assert!(
+        runtime
+            .get_session(token_hash(&second_token), "proxy.example.com")
+            .unwrap()
+            .is_carrier_committed()
+    );
+
+    runtime.shutdown().await;
+    generation.stop_sessions().await;
+    generation.stop_background_tasks().await;
+}
+
+#[tokio::test]
+async fn timed_out_attempt_replays_before_successor_own_deadline() {
+    let capability = [57; 32];
+    let generation = test_runtime_generation(
+        1,
+        negotiation_runtime_config_with_deadlines(
+            capability,
+            WebCarrier::HttpsLanes,
+            false,
+            Arc::from([WebCarrier::Https, WebCarrier::HttpsLanes]),
+            [1, 5, 8, 12],
+        ),
+    );
+    let runtime = WebProcessRuntime::start(Arc::new(ArcSwap::from(Arc::clone(&generation))));
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let bootstrap = issue_bootstrap(&runtime, "192.0.2.10");
+    let hello = frame::encode(FrameType::Hello, 0, &[1]);
+    let first_request = create_request(&bootstrap, &hello, Some(1), None);
+
+    let first = request(&listener, &runtime, first_request.clone()).await;
+    let (first_headers, _) = split_response(&first);
+    assert!(first_headers.starts_with(b"HTTP/1.1 200"));
+    assert_eq!(response_header(first_headers, "x-carrier-mode"), "https");
+    let first_token = response_header(first_headers, "x-session-token").to_string();
+
+    tokio::time::sleep(Duration::from_millis(1_100)).await;
+
+    let replay = request(&listener, &runtime, first_request).await;
+    let (replay_headers, _) = split_response(&replay);
+    assert!(replay_headers.starts_with(b"HTTP/1.1 200"));
+    assert_eq!(
+        response_header(replay_headers, "x-session-token"),
+        first_token
+    );
+    assert_eq!(
+        response_header(replay_headers, "x-carrier-state"),
+        "provisional"
+    );
+
+    let second = request(
+        &listener,
+        &runtime,
+        create_request(&bootstrap, &hello, Some(2), Some("timeout")),
+    )
+    .await;
+    let (second_headers, _) = split_response(&second);
+    assert!(second_headers.starts_with(b"HTTP/1.1 200"));
+    assert_eq!(
+        response_header(second_headers, "x-carrier-mode"),
+        "https-lanes"
+    );
+    assert_eq!(response_header(second_headers, "x-carrier-attempt"), "2");
+    assert_ne!(
+        response_header(second_headers, "x-session-token"),
+        first_token
+    );
+
+    runtime.shutdown().await;
+    generation.stop_sessions().await;
+    generation.stop_background_tasks().await;
+}
+
+#[tokio::test]
+async fn https_lane_downlink_can_arrive_before_its_uplink_open() {
+    let capability = [43; 32];
+    let mut config = negotiation_runtime_config(
+        capability,
+        WebCarrier::HttpsLanes,
+        false,
+        Arc::from([WebCarrier::HttpsLanes]),
+    );
+    config.web.timeouts.lane_open_wait_secs = 1;
+    config.web.timeouts.long_poll_secs = 2;
+    let generation = test_runtime_generation(1, config);
+    let runtime = WebProcessRuntime::start(Arc::new(ArcSwap::from(Arc::clone(&generation))));
+    let listener = Arc::new(TcpListener::bind("127.0.0.1:0").await.unwrap());
+    let bootstrap = issue_bootstrap(&runtime, "192.0.2.10");
+    let hello = frame::encode(FrameType::Hello, 0, &[1]);
+    let created = request(
+        &listener,
+        &runtime,
+        create_request(&bootstrap, &hello, Some(1), None),
+    )
+    .await;
+    let (created_headers, _) = split_response(&created);
+    let token = response_header(created_headers, "x-session-token").to_string();
+
+    let down_request = format!(
+        "POST /api/v1/down HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {token}\r\nX-Down-Cursor: 0\r\nX-Lane-ID: 7\r\nContent-Length: 0\r\nConnection: close\r\n\r\n"
+    )
+    .into_bytes();
+    let down_listener = Arc::clone(&listener);
+    let down_runtime = Arc::clone(&runtime);
+    let down =
+        tokio::spawn(async move { request(&down_listener, &down_runtime, down_request).await });
+    tokio::task::yield_now().await;
+
+    let open = frame::encode(FrameType::Open, 7, &[]);
+    let data = frame::encode(FrameType::Data, 7, &[1]);
+    let mut body = Vec::with_capacity(open.len() + data.len());
+    body.extend_from_slice(&open);
+    body.extend_from_slice(&data);
+    let mut uplink = format!(
+        "POST /api/v1/up HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {token}\r\nContent-Type: application/octet-stream\r\nX-Up-Seq: 1\r\nX-Lane-ID: 7\r\nContent-Length: {}\r\nConnection: close\r\n\r\n",
+        body.len()
+    )
+    .into_bytes();
+    uplink.extend_from_slice(&body);
+    let accepted = request(&listener, &runtime, uplink).await;
+    assert!(accepted.starts_with(b"HTTP/1.1 204"));
+
+    let down = tokio::time::timeout(Duration::from_secs(3), down)
+        .await
+        .unwrap()
+        .unwrap();
+    let (down_headers, _) = split_response(&down);
+    assert!(down_headers.starts_with(b"HTTP/1.1 200") || down_headers.starts_with(b"HTTP/1.1 204"));
+    assert!(optional_response_header(down_headers, "x-down-cursor").is_some());
+
+    runtime.shutdown().await;
+    generation.stop_sessions().await;
+    generation.stop_background_tasks().await;
+}

src/web/http/request.rs

@@ -1,65 +1,21 @@
-use std::net::{IpAddr, SocketAddr};
 use std::sync::Arc;
 
 use base64::Engine as _;
 use hyper::Request;
 use hyper::header;
-use ipnetwork::IpNetwork;
 use sha2::{Digest, Sha256};
 use subtle::ConstantTimeEq;
 
-use crate::config::{WebClientIpSource, WebRuntimeProfile, WebRuntimeVhost};
-use crate::web::manager::TokenHash;
+use crate::config::{WebRuntimeProfile, WebRuntimeVhost};
+use crate::web::manager::{
+    CarrierCapabilities, CarrierClientClass, CarrierFailure, CarrierRequest, TokenHash,
+};
 
-/// Parses one lowercase canonical Host value restricted to the public HTTPS port.
-pub(super) fn canonical_request_host<B>(request: &Request<B>) -> Option<&str> {
-    let values = request.headers().get_all(header::HOST);
-    let mut values = values.iter();
-    let value = values.next()?.to_str().ok()?;
-    if values.next().is_some() {
-        return None;
-    }
-    let authority = value.parse::<hyper::http::uri::Authority>().ok()?;
-    if authority.port_u16().is_some_and(|port| port != 443) {
-        return None;
-    }
-    let host = value.strip_suffix(":443").unwrap_or(value);
-    if authority.host() != host || host.bytes().any(|byte| byte.is_ascii_uppercase()) {
-        return None;
-    }
-    Some(host)
-}
+const USER_AGENT_CONTEXT: &[u8] = b"telemt-web-carrier-user-agent-v1\0";
 
-/// Accepts one forwarded client address or the direct address of a trusted peer.
-pub(super) fn client_ip<B>(
-    request: &Request<B>,
-    peer: SocketAddr,
-    source: WebClientIpSource,
-    trusted_proxy_cidrs: &[IpNetwork],
-) -> Option<IpAddr> {
-    if !trusted_proxy_cidrs
-        .iter()
-        .any(|network| network.contains(peer.ip()))
-    {
-        return None;
-    }
-    let header_name = match source {
-        WebClientIpSource::XForwardedFor => "x-forwarded-for",
-    };
-    let values = request.headers().get_all(header_name);
-    let mut values = values.iter();
-    let Some(value) = values.next() else {
-        return Some(peer.ip());
-    };
-    let value = value.to_str().ok()?;
-    if values.next().is_some() || value.trim() != value || value.contains(',') {
-        return None;
-    }
-    if value.is_empty() {
-        return Some(peer.ip());
-    }
-    value.parse::<IpAddr>().ok()
-}
+// Canonical host and forwarded-address provenance remain isolated from credentials.
+mod identity;
+pub(super) use identity::{canonical_request_host, carrier_ip_learning_eligible, client_ip};
 
 /// Decodes an exact canonical bridge query without allocating credential strings.
 pub(super) fn bridge_candidate(query: Option<&str>) -> ([u8; 32], bool) {
@@ -167,9 +123,148 @@ pub(super) fn canonical_u64_header<B>(request: &Request<B>, name: &'static str)
     (parsed.to_string() == value).then_some(parsed)
 }
 
+/// Parses strict bridge negotiation metadata without trusting it for authentication.
+pub(super) fn carrier_request<B>(request: &Request<B>, host: &str) -> Option<CarrierRequest> {
+    let user_agent_hash = normalized_user_agent_hash(request)?;
+    let capabilities = single_header(request, "x-carrier-capabilities");
+    let attempt = optional_canonical_u8_header(request, "x-carrier-attempt")?;
+    let failure = optional_failure_header(request)?;
+    let native_ios = native_ios_user_agent(request);
+    match (capabilities, attempt) {
+        (None, None) if failure.is_none() => {
+            if native_ios {
+                Some(CarrierRequest::ios(user_agent_hash))
+            } else {
+                Some(CarrierRequest::legacy(user_agent_hash))
+            }
+        }
+        (Some(capabilities), Some(attempt)) => {
+            let capabilities = parse_capabilities(capabilities)?;
+            if (attempt == 1) != failure.is_none() {
+                return None;
+            }
+            Some(CarrierRequest::automatic(
+                if native_ios {
+                    CarrierClientClass::Ios
+                } else {
+                    CarrierClientClass::Bridge
+                },
+                capabilities,
+                attempt,
+                failure,
+                user_agent_hash,
+            ))
+        }
+        (None, Some(attempt)) if strict_browser_hint(request, host) => {
+            if (attempt == 1) != failure.is_none() {
+                return None;
+            }
+            Some(CarrierRequest::automatic(
+                if native_ios {
+                    CarrierClientClass::Ios
+                } else {
+                    CarrierClientClass::BrowserHint
+                },
+                CarrierCapabilities::all(),
+                attempt,
+                failure,
+                user_agent_hash,
+            ))
+        }
+        _ => None,
+    }
+}
+
+fn native_ios_user_agent<B>(request: &Request<B>) -> bool {
+    single_header(request, header::USER_AGENT).is_some_and(|value| {
+        let value = value.to_ascii_lowercase();
+        value.contains("cfnetwork/") && value.contains("darwin/")
+    })
+}
+
+fn parse_capabilities(value: &str) -> Option<CarrierCapabilities> {
+    let mut bits = 0u8;
+    let mut previous = None;
+    for token in value.split(',') {
+        let index = match token {
+            "https" => 0,
+            "https-lanes" => 1,
+            "websocket" => 2,
+            "websocket-lanes" => 3,
+            _ => return None,
+        };
+        if previous.is_some_and(|previous| index <= previous) {
+            return None;
+        }
+        previous = Some(index);
+        bits |= 1 << index;
+    }
+    CarrierCapabilities::from_bits(bits)
+}
+
+fn strict_browser_hint<B>(request: &Request<B>, host: &str) -> bool {
+    single_header(request, header::ORIGIN).is_some_and(|value| value == format!("https://{host}"))
+        && single_header(request, "sec-fetch-site") == Some("same-origin")
+        && single_header(request, "sec-fetch-mode") == Some("cors")
+        && single_header(request, "sec-fetch-dest") == Some("empty")
+}
+
+fn optional_canonical_u8_header<B>(request: &Request<B>, name: &'static str) -> Option<Option<u8>> {
+    if !request.headers().contains_key(name) {
+        return Some(None);
+    }
+    canonical_u64_header(request, name)
+        .and_then(|value| u8::try_from(value).ok())
+        .filter(|value| (1..=4).contains(value))
+        .map(Some)
+}
+
+fn optional_failure_header<B>(request: &Request<B>) -> Option<Option<CarrierFailure>> {
+    if !request.headers().contains_key("x-carrier-failure") {
+        return Some(None);
+    }
+    single_header(request, "x-carrier-failure")
+        .and_then(CarrierFailure::parse)
+        .map(Some)
+}
+
+fn normalized_user_agent_hash<B>(request: &Request<B>) -> Option<[u8; 32]> {
+    let user_agent = match single_header(request, header::USER_AGENT) {
+        Some(value) => value.as_bytes(),
+        None if !request.headers().contains_key(header::USER_AGENT) => &[],
+        None => return None,
+    };
+    let mut digest = Sha256::new();
+    digest.update(USER_AGENT_CONTEXT);
+    let mut emitted = false;
+    let mut pending_whitespace = false;
+    for &byte in user_agent {
+        if byte.is_ascii_whitespace() {
+            pending_whitespace = emitted;
+        } else {
+            if pending_whitespace {
+                digest.update([b' ']);
+            }
+            digest.update([byte.to_ascii_lowercase()]);
+            emitted = true;
+            pending_whitespace = false;
+        }
+    }
+    Some(digest.finalize().into())
+}
+
+fn single_header<B>(request: &Request<B>, name: impl header::AsHeaderName) -> Option<&str> {
+    let mut values = request.headers().get_all(name).iter();
+    let value = values.next()?.to_str().ok()?;
+    values.next().is_none().then_some(value)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
+    use ipnetwork::IpNetwork;
+
+    use crate::config::{WebCarrier, WebClientIpSource};
 
     #[test]
     fn canonical_bridge_query_rejects_aliases() {
@@ -319,4 +414,129 @@ mod tests {
             .append(header::COOKIE, "state=unexpected".parse().unwrap());
         assert!(!compatible_cookie_header(&duplicate_mixed));
     }
+
+    #[test]
+    fn carrier_metadata_is_canonical_and_legacy_safe() {
+        let automatic = Request::builder()
+            .header(
+                "x-carrier-capabilities",
+                "https,https-lanes,websocket,websocket-lanes",
+            )
+            .header("x-carrier-attempt", "2")
+            .header("x-carrier-failure", "timeout")
+            .header(header::USER_AGENT, "Example  Browser")
+            .body(())
+            .unwrap();
+        let parsed = carrier_request(&automatic, "proxy.example.com").unwrap();
+        assert!(parsed.is_automatic());
+        assert_eq!(parsed.attempt(), Some(2));
+        assert_eq!(parsed.failure(), Some(CarrierFailure::Timeout));
+
+        let missing_failure = Request::builder()
+            .header(
+                "x-carrier-capabilities",
+                "https,https-lanes,websocket,websocket-lanes",
+            )
+            .header("x-carrier-attempt", "2")
+            .body(())
+            .unwrap();
+        assert!(carrier_request(&missing_failure, "proxy.example.com").is_none());
+
+        let legacy = Request::builder()
+            .header(header::USER_AGENT, "Native")
+            .body(())
+            .unwrap();
+        assert!(
+            !carrier_request(&legacy, "proxy.example.com")
+                .unwrap()
+                .is_automatic()
+        );
+
+        let reordered = Request::builder()
+            .header("x-carrier-capabilities", "websocket,https")
+            .header("x-carrier-attempt", "1")
+            .body(())
+            .unwrap();
+        assert!(carrier_request(&reordered, "proxy.example.com").is_none());
+    }
+
+    #[test]
+    fn native_ios_user_agent_classifies_without_overriding_capabilities() {
+        let metadata_free = Request::builder()
+            .header(
+                header::USER_AGENT,
+                "Telemt/1 CFNetwork/1498.700.2 Darwin/23.6.0",
+            )
+            .body(())
+            .unwrap();
+        let parsed = carrier_request(&metadata_free, "proxy.example.com").unwrap();
+        assert_eq!(parsed.class(), CarrierClientClass::Ios);
+        assert!(!parsed.is_automatic());
+        assert!(!parsed.uses_capabilities());
+
+        let automatic = Request::builder()
+            .header("x-carrier-capabilities", "https,https-lanes")
+            .header("x-carrier-attempt", "1")
+            .header(
+                header::USER_AGENT,
+                "Telemt/1 CFNetwork/1498.700.2 Darwin/23.6.0",
+            )
+            .body(())
+            .unwrap();
+        let parsed = carrier_request(&automatic, "proxy.example.com").unwrap();
+        assert_eq!(parsed.class(), CarrierClientClass::Ios);
+        assert!(parsed.is_automatic());
+        assert!(parsed.supports(WebCarrier::Https));
+        assert!(parsed.supports(WebCarrier::HttpsLanes));
+        assert!(!parsed.supports(WebCarrier::Websocket));
+        assert!(!parsed.supports(WebCarrier::WebsocketLanes));
+    }
+
+    #[test]
+    fn mapped_private_addresses_are_not_learning_evidence() {
+        for address in ["::ffff:127.0.0.1", "::ffff:10.0.0.1"] {
+            let effective_ip = address.parse().unwrap();
+            let request = Request::builder()
+                .header("x-forwarded-for", address)
+                .body(())
+                .unwrap();
+            assert!(!carrier_ip_learning_eligible(&request, effective_ip));
+        }
+        let effective_ip = "::ffff:8.8.8.8".parse().unwrap();
+        let request = Request::builder()
+            .header("x-forwarded-for", "::ffff:8.8.8.8")
+            .body(())
+            .unwrap();
+        assert!(carrier_ip_learning_eligible(&request, effective_ip));
+    }
+
+    #[test]
+    fn strict_browser_metadata_recovers_a_stripped_capability_marker() {
+        let request = Request::builder()
+            .header("x-carrier-attempt", "1")
+            .header(header::ORIGIN, "https://proxy.example.com")
+            .header("sec-fetch-site", "same-origin")
+            .header("sec-fetch-mode", "cors")
+            .header("sec-fetch-dest", "empty")
+            .body(())
+            .unwrap();
+        let parsed = carrier_request(&request, "proxy.example.com").unwrap();
+        assert_eq!(parsed.class(), CarrierClientClass::BrowserHint);
+    }
+
+    #[test]
+    fn user_agent_learning_key_is_case_and_whitespace_normalized() {
+        let first = Request::builder()
+            .header(header::USER_AGENT, "  Example\t Browser  ")
+            .body(())
+            .unwrap();
+        let second = Request::builder()
+            .header(header::USER_AGENT, "example browser")
+            .body(())
+            .unwrap();
+        assert_eq!(
+            normalized_user_agent_hash(&first),
+            normalized_user_agent_hash(&second)
+        );
+    }
 }

src/web/http/request/identity.rs

@@ -0,0 +1,111 @@
+use std::net::{IpAddr, SocketAddr};
+
+use hyper::Request;
+use hyper::header;
+use ipnetwork::IpNetwork;
+
+use crate::config::WebClientIpSource;
+
+/// Parses one lowercase canonical Host value restricted to the public HTTPS port.
+pub(in crate::web::http) fn canonical_request_host<B>(request: &Request<B>) -> Option<&str> {
+    let values = request.headers().get_all(header::HOST);
+    let mut values = values.iter();
+    let value = values.next()?.to_str().ok()?;
+    if values.next().is_some() {
+        return None;
+    }
+    let authority = value.parse::<hyper::http::uri::Authority>().ok()?;
+    if authority.port_u16().is_some_and(|port| port != 443) {
+        return None;
+    }
+    let host = value.strip_suffix(":443").unwrap_or(value);
+    if authority.host() != host || host.bytes().any(|byte| byte.is_ascii_uppercase()) {
+        return None;
+    }
+    Some(host)
+}
+
+/// Accepts one forwarded client address or the direct address of a trusted peer.
+pub(in crate::web::http) fn client_ip<B>(
+    request: &Request<B>,
+    peer: SocketAddr,
+    source: WebClientIpSource,
+    trusted_proxy_cidrs: &[IpNetwork],
+) -> Option<IpAddr> {
+    if !trusted_proxy_cidrs
+        .iter()
+        .any(|network| network.contains(peer.ip()))
+    {
+        return None;
+    }
+    let header_name = match source {
+        WebClientIpSource::XForwardedFor => "x-forwarded-for",
+    };
+    let values = request.headers().get_all(header_name);
+    let mut values = values.iter();
+    let Some(value) = values.next() else {
+        return Some(peer.ip());
+    };
+    let value = value.to_str().ok()?;
+    if values.next().is_some() || value.trim() != value || value.contains(',') {
+        return None;
+    }
+    if value.is_empty() {
+        return Some(peer.ip());
+    }
+    value.parse::<IpAddr>().ok()
+}
+
+/// Allows IP learning only for one explicit globally routable forwarded address.
+pub(in crate::web::http) fn carrier_ip_learning_eligible<B>(
+    request: &Request<B>,
+    effective_ip: IpAddr,
+) -> bool {
+    let mut values = request.headers().get_all("x-forwarded-for").iter();
+    let Some(value) = values.next().and_then(|value| value.to_str().ok()) else {
+        return false;
+    };
+    if values.next().is_some()
+        || value.trim() != value
+        || value.contains(',')
+        || value.parse::<IpAddr>().ok() != Some(effective_ip)
+    {
+        return false;
+    }
+    globally_routable(effective_ip)
+}
+
+fn globally_routable(address: IpAddr) -> bool {
+    match address {
+        IpAddr::V4(address) => globally_routable_v4(address),
+        IpAddr::V6(address) => {
+            if let Some(address) = address.to_ipv4_mapped() {
+                return globally_routable_v4(address);
+            }
+            let segments = address.segments();
+            !address.is_unspecified()
+                && !address.is_loopback()
+                && segments[0] & 0xfe00 != 0xfc00
+                && segments[0] & 0xffc0 != 0xfe80
+                && segments[0] & 0xff00 != 0xff00
+                && !(segments[0] == 0x2001 && segments[1] == 0x0db8)
+        }
+    }
+}
+
+fn globally_routable_v4(address: std::net::Ipv4Addr) -> bool {
+    let [a, b, c, _] = address.octets();
+    !(a == 0
+        || a == 10
+        || a == 127
+        || (a == 100 && (64..=127).contains(&b))
+        || (a == 169 && b == 254)
+        || (a == 172 && (16..=31).contains(&b))
+        || (a == 192 && b == 0 && c == 0)
+        || (a == 192 && b == 0 && c == 2)
+        || (a == 192 && b == 168)
+        || (a == 198 && (b == 18 || b == 19))
+        || (a == 198 && b == 51 && c == 100)
+        || (a == 203 && b == 0 && c == 113)
+        || a >= 224)
+}

src/web/http/session.rs

@@ -0,0 +1,210 @@
+use std::net::IpAddr;
+use std::sync::Arc;
+
+use hyper::header::{self, HeaderName, HeaderValue};
+use hyper::{Method, Request, StatusCode};
+
+use super::body::{CollectBodyError, CollectedBody, RequestBody, collect_body};
+use super::decoy::serve_decoy;
+use super::request::{binary_content_type, carrier_ip_learning_eligible, carrier_request};
+use super::response::{
+    carrier_empty, carrier_headers, full_response, insert_header, service_unavailable,
+};
+use super::{HttpResponse, request_trace};
+use crate::config::WebRuntimeVhost;
+use crate::web::frame::{self, FrameType};
+use crate::web::manager::{ManagerError, TokenHash, WebProcessRuntime};
+use crate::web::trace::{TraceDirection, TraceLifecycleEvent, TraceRoute};
+
+const CREATE_BODY_LIMIT: usize = 64;
+
+/// Handles session creation, replacement replay, and authenticated closure.
+pub(super) async fn handle_session(
+    request: Request<RequestBody>,
+    runtime: Arc<WebProcessRuntime>,
+    vhost: Arc<WebRuntimeVhost>,
+    token_hash: TokenHash,
+    client_ip: IpAddr,
+) -> HttpResponse {
+    if request.headers().contains_key("x-lane-id") {
+        return serve_decoy(request, vhost, true, &runtime).await;
+    }
+    if request.method() == Method::DELETE {
+        if request.headers().contains_key(header::CONTENT_TYPE) {
+            return serve_decoy(request, vhost, true, &runtime).await;
+        }
+        if let Some(trace) = request_trace(&request)
+            && let Ok(session) = runtime.get_session(token_hash, &vhost.host)
+        {
+            trace.set_route(TraceRoute::Session);
+            trace.bind_identity(session.trace_identity());
+        }
+        let CollectedBody {
+            request,
+            body,
+            _body_budget,
+        } = match collect_body(request, &runtime, 1, true).await {
+            Ok(result) => result,
+            Err(CollectBodyError::Limit) => return service_unavailable(),
+            Err(CollectBodyError::Invalid(request)) => {
+                return serve_decoy(request, vhost, true, &runtime).await;
+            }
+        };
+        if !body.is_empty() || runtime.close_token(token_hash, &vhost.host).is_err() {
+            return serve_decoy(request, vhost, true, &runtime).await;
+        }
+        return carrier_empty(StatusCode::NO_CONTENT);
+    }
+    if request.method() != Method::POST || !binary_content_type(&request) {
+        return serve_decoy(request, vhost, true, &runtime).await;
+    }
+    let Some(carrier_request) = carrier_request(&request, &vhost.host) else {
+        return serve_decoy(request, vhost, true, &runtime).await;
+    };
+    let ip_learning_eligible = carrier_ip_learning_eligible(&request, client_ip);
+    let Some((trace_session_id, profile)) =
+        runtime.bootstrap_trace_identity(token_hash, &vhost.host)
+    else {
+        return serve_decoy(request, vhost, true, &runtime).await;
+    };
+    if let Some(trace) = request_trace(&request) {
+        trace.set_route(TraceRoute::Session);
+        trace.bind_profile(&profile, trace_session_id);
+    }
+    let CollectedBody {
+        request,
+        body,
+        _body_budget,
+    } = match collect_body(request, &runtime, CREATE_BODY_LIMIT, false).await {
+        Ok(result) => result,
+        Err(CollectBodyError::Limit) => return service_unavailable(),
+        Err(CollectBodyError::Invalid(request)) => {
+            return serve_decoy(request, vhost, true, &runtime).await;
+        }
+    };
+    if let Some(trace) = request_trace(&request) {
+        trace.record_frames(
+            TraceDirection::Request,
+            &body,
+            &runtime.active_generation().config().web.limits,
+        );
+    }
+    match runtime.create_session(
+        token_hash,
+        &vhost.host,
+        client_ip,
+        &body,
+        carrier_request,
+        ip_learning_eligible,
+    ) {
+        Ok(result) => {
+            let welcome = frame::encode(FrameType::Welcome, 0, &[]);
+            if let Some(trace) = request_trace(&request) {
+                trace.register_redaction(result.token.as_bytes());
+                trace.record_frames(
+                    TraceDirection::Response,
+                    &welcome,
+                    &runtime.active_generation().config().web.limits,
+                );
+            }
+            let mut response = full_response(StatusCode::OK, welcome);
+            carrier_headers(&mut response);
+            insert_header(
+                &mut response,
+                HeaderName::from_static("x-session-token"),
+                &result.token,
+            );
+            response.headers_mut().insert(
+                HeaderName::from_static("x-carrier-mode"),
+                HeaderValue::from_static(result.carrier.as_str()),
+            );
+            response.headers_mut().insert(
+                HeaderName::from_static("x-down-cursor"),
+                HeaderValue::from_static("0"),
+            );
+            if let Some(attempt) = result.attempt {
+                insert_header(
+                    &mut response,
+                    HeaderName::from_static("x-carrier-attempt"),
+                    &attempt.to_string(),
+                );
+            }
+            if let Some(candidate_count) = result.candidate_count {
+                insert_header(
+                    &mut response,
+                    HeaderName::from_static("x-carrier-candidate-count"),
+                    &candidate_count.to_string(),
+                );
+                insert_header(
+                    &mut response,
+                    HeaderName::from_static("x-carrier-deadline"),
+                    &result.deadline_secs.unwrap_or_default().to_string(),
+                );
+                if let Some(state) = result.carrier_state {
+                    insert_header(
+                        &mut response,
+                        HeaderName::from_static("x-carrier-state"),
+                        state,
+                    );
+                }
+            }
+            response
+        }
+        Err(ManagerError::Committed) => {
+            let mut response = carrier_empty(StatusCode::CONFLICT);
+            if let Some(echo) =
+                runtime.carrier_echo(token_hash, &vhost.host, client_ip, carrier_request)
+            {
+                response.headers_mut().insert(
+                    HeaderName::from_static("x-carrier-mode"),
+                    HeaderValue::from_static(echo.carrier.as_str()),
+                );
+                insert_header(
+                    &mut response,
+                    HeaderName::from_static("x-carrier-attempt"),
+                    &echo.attempt.to_string(),
+                );
+                insert_header(
+                    &mut response,
+                    HeaderName::from_static("x-carrier-candidate-count"),
+                    &echo.candidate_count.to_string(),
+                );
+                insert_header(
+                    &mut response,
+                    HeaderName::from_static("x-carrier-deadline"),
+                    &echo.deadline_secs.to_string(),
+                );
+                insert_header(
+                    &mut response,
+                    HeaderName::from_static("x-carrier-state"),
+                    echo.state,
+                );
+            }
+            response
+        }
+        Err(
+            error @ (ManagerError::Limit | ManagerError::Backpressure | ManagerError::Concurrent),
+        ) => {
+            runtime.trace().record_profile_lifecycle(
+                client_ip,
+                Some(trace_session_id),
+                &profile,
+                TraceLifecycleEvent::SessionRejected,
+                None,
+                Some(error.as_str()),
+            );
+            service_unavailable()
+        }
+        Err(error) => {
+            runtime.trace().record_profile_lifecycle(
+                client_ip,
+                Some(trace_session_id),
+                &profile,
+                TraceLifecycleEvent::SessionRejected,
+                None,
+                Some(error.as_str()),
+            );
+            serve_decoy(request, vhost, true, &runtime).await
+        }
+    }
+}

src/web/http/tests.rs

@@ -10,20 +10,85 @@ use tokio_util::sync::CancellationToken;
 
 use super::serve_connection;
 use crate::config::{
-    ProxyConfig, WebCarrier, WebClientIpSource, WebRuntimeConfig, WebRuntimeDecoy,
+    ProxyConfig, WebCarrier, WebCarriers, WebClientIpSource, WebRuntimeConfig, WebRuntimeDecoy,
     WebRuntimeProfile, WebRuntimeVhost, WebSecretMode, WebStaticAsset, WebStaticSite,
 };
 use crate::maestro::generation::test_runtime_generation;
 use crate::web::frame::{self, FrameType};
 use crate::web::manager::WebProcessRuntime;
 
+#[path = "legacy_tests.rs"]
+mod legacy_tests;
+#[path = "negotiation_tests.rs"]
+mod negotiation_tests;
+
+const TEST_CARRIER_DEADLINES_SECS: [u64; 4] = [3, 5, 8, 12];
+
 pub(super) fn runtime_config(capability: [u8; 32], carrier: WebCarrier) -> ProxyConfig {
+    runtime_config_with_carriers(capability, carrier, false, true, Arc::from([carrier]))
+}
+
+pub(super) fn negotiation_runtime_config(
+    capability: [u8; 32],
+    carrier: WebCarrier,
+    carrier_learning: bool,
+    carriers: Arc<[WebCarrier]>,
+) -> ProxyConfig {
+    runtime_config_with_carriers(capability, carrier, true, carrier_learning, carriers)
+}
+
+fn runtime_config_with_carriers(
+    capability: [u8; 32],
+    carrier: WebCarrier,
+    carrier_negotiation_enabled: bool,
+    carrier_learning: bool,
+    carriers: Arc<[WebCarrier]>,
+) -> ProxyConfig {
+    runtime_config_with_carriers_and_deadlines(
+        capability,
+        carrier,
+        carrier_negotiation_enabled,
+        carrier_learning,
+        carriers,
+        TEST_CARRIER_DEADLINES_SECS,
+    )
+}
+
+pub(super) fn negotiation_runtime_config_with_deadlines(
+    capability: [u8; 32],
+    carrier: WebCarrier,
+    carrier_learning: bool,
+    carriers: Arc<[WebCarrier]>,
+    carrier_negotiation_deadlines_secs: [u64; 4],
+) -> ProxyConfig {
+    runtime_config_with_carriers_and_deadlines(
+        capability,
+        carrier,
+        true,
+        carrier_learning,
+        carriers,
+        carrier_negotiation_deadlines_secs,
+    )
+}
+
+fn runtime_config_with_carriers_and_deadlines(
+    capability: [u8; 32],
+    carrier: WebCarrier,
+    carrier_negotiation_enabled: bool,
+    carrier_learning: bool,
+    carriers: Arc<[WebCarrier]>,
+    carrier_negotiation_deadlines_secs: [u64; 4],
+) -> ProxyConfig {
     let profile = Arc::new(WebRuntimeProfile {
         host: "proxy.example.com".to_string(),
         public_addr: "203.0.113.10:443".parse().unwrap(),
         user: "alice".to_string(),
         secret_mode: WebSecretMode::Plain,
         carrier,
+        carrier_negotiation_enabled,
+        carrier_learning,
+        carriers: Arc::clone(&carriers),
+        carrier_negotiation_deadlines_secs,
         capability,
         key_fingerprint: "0000000000000000".to_string(),
         max_sessions: 4,
@@ -63,6 +128,13 @@ pub(super) fn runtime_config(capability: [u8; 32], carrier: WebCarrier) -> Proxy
     let mut config = ProxyConfig::default();
     config.web.enabled = true;
     config.web.carrier = carrier;
+    config.web.carriers = if carrier_negotiation_enabled {
+        WebCarriers::Enabled(carriers.to_vec())
+    } else {
+        WebCarriers::Disabled
+    };
+    config.web.carrier_learning = carrier_learning;
+    config.web.timeouts.carrier_negotiation_deadlines_secs = carrier_negotiation_deadlines_secs;
     config.web.limits.max_bootstraps_per_ip = 1;
     config.web.timeouts.shutdown_secs = 1;
     config.web.runtime = Some(Arc::new(WebRuntimeConfig {
@@ -106,7 +178,7 @@ pub(super) fn split_response(response: &[u8]) -> (&[u8], &[u8]) {
     (&response[..separator], &response[separator + 4..])
 }
 
-fn response_header<'a>(headers: &'a [u8], name: &str) -> &'a str {
+pub(super) fn response_header<'a>(headers: &'a [u8], name: &str) -> &'a str {
     std::str::from_utf8(headers)
         .unwrap()
         .lines()
@@ -189,8 +261,8 @@ async fn https_carrier_bootstraps_and_closes_one_session() {
     );
     assert!(
         next_root_body
-            .windows(21)
-            .any(|value| value == b"carrier='https-lanes'")
+            .windows(b"const negotiationEnabled=false".len())
+            .any(|value| value == b"const negotiationEnabled=false")
     );
 
     let close = format!(
@@ -375,7 +447,7 @@ async fn https_lanes_is_advertised_and_requires_canonical_lane_headers() {
     let root_response = request(&listener, &runtime, root).await;
     let (_, root_body) = split_response(&root_response);
     let root_body = std::str::from_utf8(root_body).unwrap();
-    assert!(root_body.contains("carrier='https-lanes'"));
+    assert!(root_body.contains("const negotiationEnabled=false"));
     let bootstrap = root_body
         .split_once("bootstrap=\"")
         .and_then(|(_, suffix)| suffix.split_once('"'))
@@ -437,99 +509,3 @@ async fn https_lanes_is_advertised_and_requires_canonical_lane_headers() {
     generation.stop_sessions().await;
     generation.stop_background_tasks().await;
 }
-
-#[tokio::test]
-async fn windows_restricted_webview_empty_cookie_preserves_the_carrier_flow() {
-    for (index, carrier) in [WebCarrier::Https, WebCarrier::HttpsLanes]
-        .into_iter()
-        .enumerate()
-    {
-        let capability = [12 + index as u8; 32];
-        let mut config = runtime_config(capability, carrier);
-        config.web.timeouts.long_poll_secs = 0;
-        let generation = test_runtime_generation(1, config);
-        let active_runtime = Arc::new(ArcSwap::from(Arc::clone(&generation)));
-        let runtime = WebProcessRuntime::start(active_runtime);
-        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
-        let encoded = base64::engine::general_purpose::URL_SAFE_NO_PAD.encode(capability);
-        let root = format!(
-            "GET /?bridge={encoded} HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nCookie:\r\nConnection: close\r\n\r\n"
-        )
-        .into_bytes();
-        let root_response = request(&listener, &runtime, root).await;
-        let (root_headers, root_body) = split_response(&root_response);
-        assert!(root_headers.starts_with(b"HTTP/1.1 200"));
-        let root_body = std::str::from_utf8(root_body).unwrap();
-        let bootstrap = root_body
-            .split_once("bootstrap=\"")
-            .and_then(|(_, suffix)| suffix.split_once('"'))
-            .map(|(token, _)| token)
-            .unwrap();
-
-        let hello = frame::encode(FrameType::Hello, 0, &[1]);
-        let create = |cookie: &str| {
-            let mut request = format!(
-                "POST /api/v1/session HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {bootstrap}\r\nContent-Type: application/octet-stream\r\n{cookie}Content-Length: {}\r\nConnection: close\r\n\r\n",
-                hello.len()
-            )
-            .into_bytes();
-            request.extend_from_slice(&hello);
-            request
-        };
-        let nonempty_cookie =
-            request(&listener, &runtime, create("Cookie: state=unexpected\r\n")).await;
-        assert!(!nonempty_cookie.starts_with(b"HTTP/1.1 200"));
-        let duplicate_cookie = request(
-            &listener,
-            &runtime,
-            create("Cookie:\r\nCookie: state=unexpected\r\n"),
-        )
-        .await;
-        assert!(!duplicate_cookie.starts_with(b"HTTP/1.1 200"));
-
-        let create_response = request(&listener, &runtime, create("Cookie:\r\n")).await;
-        let (create_headers, create_body) = split_response(&create_response);
-        assert!(create_headers.starts_with(b"HTTP/1.1 200"));
-        assert_eq!(
-            response_header(create_headers, "x-carrier-mode"),
-            carrier.as_str()
-        );
-        assert_eq!(create_body, frame::encode(FrameType::Welcome, 0, &[]));
-        let session = response_header(create_headers, "x-session-token").to_string();
-        let lane = (carrier == WebCarrier::HttpsLanes)
-            .then_some("X-Lane-ID: 0\r\n")
-            .unwrap_or_default();
-
-        let pong = frame::encode(FrameType::Pong, 0, &[]);
-        let mut uplink = format!(
-            "POST /api/v1/up HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {session}\r\nContent-Type: application/octet-stream\r\nCookie:\r\nX-Up-Seq: 1\r\n{lane}Content-Length: {}\r\nConnection: close\r\n\r\n",
-            pong.len()
-        )
-        .into_bytes();
-        uplink.extend_from_slice(&pong);
-        let uplink_response = request(&listener, &runtime, uplink).await;
-        let (uplink_headers, _) = split_response(&uplink_response);
-        assert!(uplink_headers.starts_with(b"HTTP/1.1 204"));
-        assert_eq!(response_header(uplink_headers, "x-up-ack"), "1");
-
-        let downlink = format!(
-            "POST /api/v1/down HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {session}\r\nCookie:\r\nX-Down-Cursor: 0\r\n{lane}Content-Length: 0\r\nConnection: close\r\n\r\n"
-        )
-        .into_bytes();
-        let downlink_response = request(&listener, &runtime, downlink).await;
-        let (downlink_headers, _) = split_response(&downlink_response);
-        assert!(downlink_headers.starts_with(b"HTTP/1.1 204"));
-        assert_eq!(response_header(downlink_headers, "x-down-cursor"), "0");
-
-        let close = format!(
-            "DELETE /api/v1/session HTTP/1.1\r\nHost: proxy.example.com\r\nX-Forwarded-For: 192.0.2.10\r\nAuthorization: Bearer {session}\r\nCookie:\r\nContent-Length: 0\r\nConnection: close\r\n\r\n"
-        )
-        .into_bytes();
-        let close_response = request(&listener, &runtime, close).await;
-        assert!(close_response.starts_with(b"HTTP/1.1 204"));
-
-        runtime.shutdown().await;
-        generation.stop_sessions().await;
-        generation.stop_background_tasks().await;
-    }
-}

src/web/http/websocket.rs

@@ -200,7 +200,6 @@ impl AsyncRead for ConnectionIo {
             Poll::Ready(Ok(())) => {
                 let filled = limited.filled().len();
                 boundary.observe(limited.filled());
-                drop(limited);
                 buffer.advance(filled);
                 Poll::Ready(Ok(()))
             }
@@ -244,6 +243,7 @@ struct ParsedUpgrade {
     protocol: String,
     accept: String,
     carrier: ParsedCarrier,
+    acknowledge_commit: bool,
 }
 
 pub(super) async fn handle(
@@ -272,6 +272,10 @@ pub(super) async fn handle(
         (ParsedCarrier::Lane(lane_id), WebCarrier::WebsocketLanes) => WebSocketKind::Lane(lane_id),
         _ => return serve_decoy(request, vhost, true, &runtime).await,
     };
+    let mut probe_reservation = match session.reserve_websocket_probe(parsed.acknowledge_commit) {
+        Ok(reservation) => reservation,
+        Err(_) => return serve_decoy(request, vhost, true, &runtime).await,
+    };
     let mut lane_reservation = match kind {
         WebSocketKind::Multiplex => None,
         WebSocketKind::Lane(lane_id) => match session.reserve_websocket_lane(lane_id) {
@@ -279,22 +283,29 @@ pub(super) async fn handle(
             Err(_) => return serve_decoy(request, vhost, true, &runtime).await,
         },
     };
-    let timeouts = runtime.active_generation().config().web.timeouts.clone();
+    let timeouts = session.timeouts().clone();
     let connection = match runtime
         .admit_websocket(
             session.profile_key(),
             session.trace_session_id(),
+            session.token_hash(),
             effective_ip,
             kind,
             BASE_BUDGET_BYTES,
             Duration::from_secs(timeouts.long_poll_secs),
             Duration::from_secs(timeouts.websocket_eviction_secs),
+            session.carrier_cancellation(),
         )
         .await
     {
         Ok(connection) => connection,
         Err(_) => return serve_decoy(request, vhost, true, &runtime).await,
     };
+    if let Some(reservation) = probe_reservation.as_mut()
+        && reservation.bind(connection.id()).is_err()
+    {
+        return serve_decoy(request, vhost, true, &runtime).await;
+    }
     let trace_context = runtime.trace().websocket_context(
         &request,
         peer.ip(),
@@ -324,7 +335,9 @@ pub(super) async fn handle(
             driver_session,
             connection,
             lane_reservation.take(),
+            probe_reservation.take(),
             trace_context,
+            parsed.acknowledge_commit,
         )
         .await;
     });
@@ -376,21 +389,17 @@ fn parse_upgrade<B>(request: &Request<B>) -> Option<ParsedUpgrade> {
     {
         return None;
     }
-    let (token, carrier) = if let Some(token) = protocol.strip_prefix("tproxy-v1.") {
-        (token, ParsedCarrier::Multiplex)
+    let (token, carrier, acknowledge_commit) =
+        if let Some(token) = protocol.strip_prefix("tproxy-auto-v1.") {
+            (token, ParsedCarrier::Multiplex, true)
+        } else if let Some(lane) = protocol.strip_prefix("tproxy-auto-lane-v1.") {
+            let (token, lane_id) = parse_lane_protocol(lane)?;
+            (token, ParsedCarrier::Lane(lane_id), true)
+        } else if let Some(token) = protocol.strip_prefix("tproxy-v1.") {
+            (token, ParsedCarrier::Multiplex, false)
         } else if let Some(lane) = protocol.strip_prefix("tproxy-lane-v1.") {
-        let (token, lane_id) = lane.split_once('.')?;
-        if lane_id.is_empty()
-            || lane_id.starts_with('+')
-            || (lane_id.len() > 1 && lane_id.starts_with('0'))
-        {
-            return None;
-        }
-        let lane_id = lane_id
-            .parse::<u32>()
-            .ok()
-            .filter(|value| (1..=crate::web::frame::MAX_STREAM_ID).contains(value))?;
-        (token, ParsedCarrier::Lane(lane_id))
+            let (token, lane_id) = parse_lane_protocol(lane)?;
+            (token, ParsedCarrier::Lane(lane_id), false)
         } else {
             return None;
         };
@@ -412,13 +421,26 @@ fn parse_upgrade<B>(request: &Request<B>) -> Option<ParsedUpgrade> {
         protocol: protocol.to_string(),
         accept: base64::engine::general_purpose::STANDARD.encode(accept.finalize()),
         carrier,
+        acknowledge_commit,
     })
 }
 
-fn single_header<'a, B>(
-    request: &'a Request<B>,
-    name: impl hyper::header::AsHeaderName,
-) -> Option<&'a str> {
+fn parse_lane_protocol(value: &str) -> Option<(&str, u32)> {
+    let (token, lane_id) = value.split_once('.')?;
+    if lane_id.is_empty()
+        || lane_id.starts_with('+')
+        || (lane_id.len() > 1 && lane_id.starts_with('0'))
+    {
+        return None;
+    }
+    let lane_id = lane_id
+        .parse::<u32>()
+        .ok()
+        .filter(|value| (1..=crate::web::frame::MAX_STREAM_ID).contains(value))?;
+    Some((token, lane_id))
+}
+
+fn single_header<B>(request: &Request<B>, name: impl hyper::header::AsHeaderName) -> Option<&str> {
     let mut values = request.headers().get_all(name).iter();
     let value = values.next()?.to_str().ok()?;
     values.next().is_none().then_some(value)

src/web/http/websocket/driver.rs

@@ -2,31 +2,46 @@ use std::sync::Arc;
 use std::time::{Duration, Instant};
 
 use bytes::Bytes;
-use futures_util::{SinkExt, StreamExt};
 use hyper_util::rt::TokioIo;
 use tokio_tungstenite::WebSocketStream;
 use tokio_tungstenite::tungstenite::protocol::{Message, Role, WebSocketConfig};
 use tokio_util::sync::CancellationToken;
 
 use super::ConnectionIo;
-use crate::web::manager::{
-    ManagerError, WebProcessRuntime, WebSocketBudgetLease, WebSocketConnection,
-};
-use crate::web::session::{WebSession, WebSocketLaneReservation};
+use crate::web::manager::{WebProcessRuntime, WebSocketBudgetLease, WebSocketConnection};
+use crate::web::session::{WebSession, WebSocketLaneReservation, WebSocketProbeReservation};
 use crate::web::trace::{TraceDirection, TraceWebSocketContext};
 
 const READ_BUFFER_BYTES: usize = 64 * 1024;
 const WRITE_BUFFER_BYTES: usize = 64 * 1024;
 
+// Cancellation-safe message I/O and budget retries remain separate from carrier loops.
+mod io;
+// Per-lane carrier state remains isolated from the multiplexed driver.
+mod lane;
+use io::{flush, process_multiplex, read_message, record_message, reserve_data, send};
+use lane::run_lane;
+
 pub(super) async fn run_upgraded(
     on_upgrade: hyper::upgrade::OnUpgrade,
     runtime: Arc<WebProcessRuntime>,
     session: Arc<WebSession>,
     connection: WebSocketConnection,
     mut lane_reservation: Option<WebSocketLaneReservation>,
+    _probe_reservation: Option<WebSocketProbeReservation>,
     trace: Option<TraceWebSocketContext>,
+    acknowledge_commit: bool,
 ) {
-    let Ok(upgraded) = on_upgrade.await else {
+    let cancellation = connection.cancellation();
+    let timeouts = session.timeouts().clone();
+    let upgraded = tokio::select! {
+        _ = cancellation.cancelled() => return,
+        result = tokio::time::timeout(
+            Duration::from_secs(timeouts.websocket_upgrade_secs),
+            on_upgrade,
+        ) => result,
+    };
+    let Ok(Ok(upgraded)) = upgraded else {
         return;
     };
     let Ok(parts) = upgraded.downcast::<TokioIo<ConnectionIo>>() else {
@@ -34,7 +49,7 @@ pub(super) async fn run_upgraded(
     };
     let mut io = parts.io.into_inner();
     io.enable_websocket(parts.read_buf);
-    let limits = runtime.active_generation().config().web.limits.clone();
+    let limits = session.limits().clone();
     let config = WebSocketConfig::default()
         .read_buffer_size(READ_BUFFER_BYTES)
         .write_buffer_size(WRITE_BUFFER_BYTES)
@@ -46,8 +61,9 @@ pub(super) async fn run_upgraded(
         .max_message_size(Some(limits.carrier_batch_bytes))
         .max_frame_size(Some(limits.carrier_batch_bytes));
     let mut socket = WebSocketStream::from_raw_socket(io, Role::Server, Some(config)).await;
-    connection.mark_opened();
-    let cancellation = connection.cancellation();
+    if !connection.mark_opened() {
+        return;
+    }
     if let Some(reservation) = lane_reservation.as_mut() {
         let _ = run_lane(
             &mut socket,
@@ -57,6 +73,7 @@ pub(super) async fn run_upgraded(
             reservation,
             cancellation.clone(),
             trace.as_ref(),
+            acknowledge_commit,
         )
         .await;
     } else {
@@ -67,22 +84,20 @@ pub(super) async fn run_upgraded(
             &connection,
             cancellation.clone(),
             trace.as_ref(),
+            acknowledge_commit,
         )
         .await;
     }
-    let eviction = Duration::from_secs(
-        runtime
-            .active_generation()
-            .config()
-            .web
-            .timeouts
-            .websocket_eviction_secs,
-    );
-    let _ = tokio::time::timeout(eviction, socket.close(None)).await;
+    let eviction = Duration::from_secs(timeouts.websocket_eviction_secs);
+    tokio::select! {
+        biased;
+        _ = cancellation.cancelled() => {}
+        _ = tokio::time::timeout(eviction, socket.close(None)) => {}
+    }
     if let Some(reservation) = lane_reservation {
         session.close_websocket_lane(reservation.lane_id());
         drop(reservation);
-    } else {
+    } else if !acknowledge_commit || session.is_carrier_committed() {
         session.close();
     }
 }
@@ -96,6 +111,7 @@ async fn run_multiplex(
     connection: &WebSocketConnection,
     cancellation: CancellationToken,
     trace: Option<&TraceWebSocketContext>,
+    acknowledge_commit: bool,
 ) -> Result<(), ()> {
     let mut sequence = 1u64;
     let mut cursor = 0u64;
@@ -104,11 +120,18 @@ async fn run_multiplex(
     let mut read_budget = None;
     let liveness_interval = connection.liveness_interval();
     let mut next_ping = Instant::now() + liveness_interval;
+    let open_deadline =
+        Instant::now() + Duration::from_secs(session.timeouts().websocket_open_secs);
+    let backpressure_timeout = Duration::from_secs(session.timeouts().websocket_backpressure_secs);
+    let write_timeout = Duration::from_secs(session.timeouts().websocket_write_secs);
+    let maximum_message = session.limits().carrier_batch_bytes;
+    let mut active = false;
     loop {
         let down = session.poll_down(cursor);
         tokio::pin!(down);
         let event = tokio::select! {
             _ = cancellation.cancelled() => return Err(()),
+            _ = tokio::time::sleep_until(open_deadline.into()), if !active => return Err(()),
             _ = tokio::time::sleep_until(next_ping.into()) => DriverEvent::Liveness,
             incoming = read_message(
                 socket,
@@ -116,6 +139,8 @@ async fn run_multiplex(
                 session.profile_key(),
                 &cancellation,
                 &mut read_budget,
+                maximum_message,
+                backpressure_timeout,
             ) => {
                 DriverEvent::Incoming(incoming?)
             }
@@ -125,179 +150,13 @@ async fn run_multiplex(
             DriverEvent::Incoming((message, _budget)) => match message {
                 Message::Binary(body) => {
                     let started = Instant::now();
-                    let result =
-                        process_multiplex(runtime, session, sequence, &body, &cancellation).await;
-                    record_message(
-                        runtime,
-                        trace,
-                        TraceDirection::Request,
-                        "binary",
-                        &body,
-                        started,
-                    );
-                    result?;
-                    sequence = sequence.checked_add(1).ok_or(())?;
-                    connection.mark_peer_activity();
-                    next_ping = Instant::now() + liveness_interval;
-                }
-                Message::Pong(payload) => {
-                    record_message(
-                        runtime,
-                        trace,
-                        TraceDirection::Request,
-                        "pong",
-                        &payload,
-                        Instant::now(),
-                    );
-                    connection.mark_peer_activity();
-                    next_ping = Instant::now() + liveness_interval;
-                }
-                Message::Ping(payload) => {
-                    let started = Instant::now();
-                    flush(socket, runtime).await?;
-                    record_message(
-                        runtime,
-                        trace,
-                        TraceDirection::Request,
-                        "ping",
-                        &payload,
-                        started,
-                    );
-                    record_message(
-                        runtime,
-                        trace,
-                        TraceDirection::Response,
-                        "pong",
-                        &payload,
-                        started,
-                    );
-                    connection.mark_peer_activity();
-                    next_ping = Instant::now() + liveness_interval;
-                }
-                Message::Close(_) => {
-                    record_message(
-                        runtime,
-                        trace,
-                        TraceDirection::Request,
-                        "close",
-                        &[],
-                        Instant::now(),
-                    );
-                    return Ok(());
-                }
-                Message::Text(text) => {
-                    record_message(
-                        runtime,
-                        trace,
-                        TraceDirection::Request,
-                        "text",
-                        text.as_bytes(),
-                        Instant::now(),
-                    );
-                    return Err(());
-                }
-                Message::Frame(_) => return Err(()),
-            },
-            DriverEvent::Down(result) => {
-                if result.body.is_empty() {
-                    let started = Instant::now();
-                    send(socket, runtime, Message::Ping(Bytes::new())).await?;
-                    record_message(
-                        runtime,
-                        trace,
-                        TraceDirection::Response,
-                        "ping",
-                        &[],
-                        started,
-                    );
-                    next_ping = Instant::now() + liveness_interval;
-                } else {
-                    let _budget = reserve_data(
-                        runtime,
-                        session.profile_key(),
-                        result.body.len(),
-                        &cancellation,
-                    )
-                    .await?;
-                    let body = result.body;
-                    let started = Instant::now();
-                    if trace.is_some() {
-                        send(socket, runtime, Message::Binary(body.clone())).await?;
-                        record_message(
-                            runtime,
-                            trace,
-                            TraceDirection::Response,
-                            "binary",
-                            &body,
-                            started,
-                        );
-                    } else {
-                        send(socket, runtime, Message::Binary(body)).await?;
-                    }
-                    connection.mark_progress();
-                }
-                cursor = result.next_cursor;
-            }
-            DriverEvent::Liveness => {
-                let started = Instant::now();
-                send(socket, runtime, Message::Ping(Bytes::new())).await?;
-                record_message(
-                    runtime,
-                    trace,
-                    TraceDirection::Response,
-                    "ping",
-                    &[],
-                    started,
-                );
-                next_ping = Instant::now() + liveness_interval;
-            }
-        }
-    }
-}
-
-async fn run_lane(
-    socket: &mut CarrierSocket,
-    runtime: &Arc<WebProcessRuntime>,
-    session: &Arc<WebSession>,
-    connection: &WebSocketConnection,
-    reservation: &mut WebSocketLaneReservation,
-    cancellation: CancellationToken,
-    trace: Option<&TraceWebSocketContext>,
-) -> Result<(), ()> {
-    let mut sequence = 1u64;
-    let mut cursor = 0u64;
-    // Lane reads use the same cancellation-safe fragmented-message ownership.
-    let mut read_budget = None;
-    let liveness_interval = connection.liveness_interval();
-    let mut next_ping = Instant::now() + liveness_interval;
-    loop {
-        let down = session.poll_down_lane(reservation.lane_id(), cursor);
-        tokio::pin!(down);
-        let event = tokio::select! {
-            _ = cancellation.cancelled() => return Err(()),
-            _ = tokio::time::sleep_until(next_ping.into()) => DriverEvent::Liveness,
-            incoming = read_message(
-                socket,
-                runtime,
-                session.profile_key(),
-                &cancellation,
-                &mut read_budget,
-            ) => {
-                DriverEvent::Incoming(incoming?)
-            }
-            down = &mut down => DriverEvent::Down(down.map_err(|_| ())?),
-        };
-        match event {
-            DriverEvent::Incoming((message, _budget)) => match message {
-                Message::Binary(body) => {
-                    let started = Instant::now();
-                    let result = process_lane(
+                    let result = process_multiplex(
                         runtime,
                         session,
-                        reservation,
                         sequence,
                         &body,
                         &cancellation,
+                        backpressure_timeout,
                     )
                     .await;
                     record_message(
@@ -308,7 +167,42 @@ async fn run_lane(
                         &body,
                         started,
                     );
-                    result?;
+                    let progressed = result?;
+                    if acknowledge_commit && sequence == 1 {
+                        if !session.needs_websocket_commit_ack(connection.id()) {
+                            return Err(());
+                        }
+                        let started = Instant::now();
+                        send(
+                            socket,
+                            Message::Binary(Bytes::new()),
+                            &cancellation,
+                            write_timeout,
+                        )
+                        .await?;
+                        record_message(
+                            runtime,
+                            trace,
+                            TraceDirection::Response,
+                            "carrier-ack",
+                            &[],
+                            started,
+                        );
+                        if !session.websocket_commit_ack_written(connection.id()) {
+                            session.close();
+                            return Err(());
+                        }
+                    } else if acknowledge_commit && sequence > 1 && progressed {
+                        if !session.websocket_peer_after_commit_ack(connection.id()) {
+                            return Err(());
+                        }
+                    }
+                    if !active && progressed {
+                        if !connection.mark_active() {
+                            return Err(());
+                        }
+                        active = true;
+                    }
                     sequence = sequence.checked_add(1).ok_or(())?;
                     connection.mark_peer_activity();
                     next_ping = Instant::now() + liveness_interval;
@@ -327,7 +221,7 @@ async fn run_lane(
                 }
                 Message::Ping(payload) => {
                     let started = Instant::now();
-                    flush(socket, runtime).await?;
+                    flush(socket, &cancellation, write_timeout).await?;
                     record_message(
                         runtime,
                         trace,
@@ -372,12 +266,15 @@ async fn run_lane(
                 Message::Frame(_) => return Err(()),
             },
             DriverEvent::Down(result) => {
-                if result.lane_closed {
-                    return Ok(());
-                }
                 if result.body.is_empty() {
                     let started = Instant::now();
-                    send(socket, runtime, Message::Ping(Bytes::new())).await?;
+                    send(
+                        socket,
+                        Message::Ping(Bytes::new()),
+                        &cancellation,
+                        write_timeout,
+                    )
+                    .await?;
                     record_message(
                         runtime,
                         trace,
@@ -393,12 +290,19 @@ async fn run_lane(
                         session.profile_key(),
                         result.body.len(),
                         &cancellation,
+                        backpressure_timeout,
                     )
                     .await?;
                     let body = result.body;
                     let started = Instant::now();
                     if trace.is_some() {
-                        send(socket, runtime, Message::Binary(body.clone())).await?;
+                        send(
+                            socket,
+                            Message::Binary(body.clone()),
+                            &cancellation,
+                            write_timeout,
+                        )
+                        .await?;
                         record_message(
                             runtime,
                             trace,
@@ -408,7 +312,7 @@ async fn run_lane(
                             started,
                         );
                     } else {
-                        send(socket, runtime, Message::Binary(body)).await?;
+                        send(socket, Message::Binary(body), &cancellation, write_timeout).await?;
                     }
                     connection.mark_progress();
                 }
@@ -416,7 +320,13 @@ async fn run_lane(
             }
             DriverEvent::Liveness => {
                 let started = Instant::now();
-                send(socket, runtime, Message::Ping(Bytes::new())).await?;
+                send(
+                    socket,
+                    Message::Ping(Bytes::new()),
+                    &cancellation,
+                    write_timeout,
+                )
+                .await?;
                 record_message(
                     runtime,
                     trace,
@@ -436,203 +346,3 @@ enum DriverEvent {
     Down(crate::web::session::PollResult),
     Liveness,
 }
-
-async fn read_message(
-    socket: &mut CarrierSocket,
-    runtime: &Arc<WebProcessRuntime>,
-    owner: crate::web::manager::ProfileKey,
-    cancellation: &CancellationToken,
-    retained_budget: &mut Option<WebSocketBudgetLease>,
-) -> Result<(Message, Option<WebSocketBudgetLease>), ()> {
-    tokio::select! {
-        _ = cancellation.cancelled() => return Err(()),
-        ready = socket.get_ref().readable() => ready.map_err(|_| ())?,
-    }
-    if retained_budget.is_none() {
-        let maximum = runtime
-            .active_generation()
-            .config()
-            .web
-            .limits
-            .carrier_batch_bytes;
-        *retained_budget = Some(reserve_data(runtime, owner, maximum, cancellation).await?);
-    }
-    let message = tokio::select! {
-        _ = cancellation.cancelled() => return Err(()),
-        message = socket.next() => message.ok_or(())?.map_err(|_| ())?,
-    };
-    if socket.get_ref().websocket_fragmented_message() {
-        return Ok((message, None));
-    }
-    let mut budget = retained_budget.take().ok_or(())?;
-    budget.shrink_to(message.len());
-    Ok((message, Some(budget)))
-}
-
-async fn reserve_data(
-    runtime: &Arc<WebProcessRuntime>,
-    owner: crate::web::manager::ProfileKey,
-    bytes: usize,
-    cancellation: &CancellationToken,
-) -> Result<WebSocketBudgetLease, ()> {
-    let timeout = Duration::from_secs(
-        runtime
-            .active_generation()
-            .config()
-            .web
-            .timeouts
-            .websocket_backpressure_secs,
-    );
-    tokio::time::timeout(timeout, async {
-        loop {
-            let notify = runtime.budget_notify();
-            let notified = notify.notified();
-            if let Some(budget) = runtime.try_websocket_data_budget(owner, bytes.max(1)) {
-                return Ok(budget);
-            }
-            tokio::select! {
-                _ = cancellation.cancelled() => return Err(()),
-                _ = notified => {}
-            }
-        }
-    })
-    .await
-    .map_err(|_| ())?
-}
-
-async fn process_multiplex(
-    runtime: &Arc<WebProcessRuntime>,
-    session: &Arc<WebSession>,
-    sequence: u64,
-    body: &[u8],
-    cancellation: &CancellationToken,
-) -> Result<(), ()> {
-    retry_backpressure(runtime, cancellation, || {
-        session.process_up(sequence, body).map(|_| ())
-    })
-    .await
-}
-
-async fn process_lane(
-    runtime: &Arc<WebProcessRuntime>,
-    session: &Arc<WebSession>,
-    reservation: &mut WebSocketLaneReservation,
-    sequence: u64,
-    body: &[u8],
-    cancellation: &CancellationToken,
-) -> Result<(), ()> {
-    let timeout = Duration::from_secs(
-        runtime
-            .active_generation()
-            .config()
-            .web
-            .timeouts
-            .websocket_backpressure_secs,
-    );
-    tokio::time::timeout(timeout, async {
-        loop {
-            let notify = runtime.budget_notify();
-            let notified = notify.notified();
-            match session.process_websocket_lane(reservation, sequence, body) {
-                Ok(()) => return Ok(()),
-                Err(ManagerError::Backpressure) => {}
-                Err(_) => return Err(()),
-            }
-            tokio::select! {
-                _ = cancellation.cancelled() => return Err(()),
-                _ = notified => {}
-            }
-        }
-    })
-    .await
-    .map_err(|_| ())?
-}
-
-async fn retry_backpressure<F>(
-    runtime: &Arc<WebProcessRuntime>,
-    cancellation: &CancellationToken,
-    mut operation: F,
-) -> Result<(), ()>
-where
-    F: FnMut() -> Result<(), ManagerError>,
-{
-    let timeout = Duration::from_secs(
-        runtime
-            .active_generation()
-            .config()
-            .web
-            .timeouts
-            .websocket_backpressure_secs,
-    );
-    tokio::time::timeout(timeout, async {
-        loop {
-            let notify = runtime.budget_notify();
-            let notified = notify.notified();
-            match operation() {
-                Ok(()) => return Ok(()),
-                Err(ManagerError::Backpressure) => {}
-                Err(_) => return Err(()),
-            }
-            tokio::select! {
-                _ = cancellation.cancelled() => return Err(()),
-                _ = notified => {}
-            }
-        }
-    })
-    .await
-    .map_err(|_| ())?
-}
-
-async fn send(
-    socket: &mut CarrierSocket,
-    runtime: &WebProcessRuntime,
-    message: Message,
-) -> Result<(), ()> {
-    let timeout = Duration::from_secs(
-        runtime
-            .active_generation()
-            .config()
-            .web
-            .timeouts
-            .websocket_write_secs,
-    );
-    tokio::time::timeout(timeout, socket.send(message))
-        .await
-        .map_err(|_| ())?
-        .map_err(|_| ())
-}
-
-async fn flush(socket: &mut CarrierSocket, runtime: &WebProcessRuntime) -> Result<(), ()> {
-    let timeout = Duration::from_secs(
-        runtime
-            .active_generation()
-            .config()
-            .web
-            .timeouts
-            .websocket_write_secs,
-    );
-    tokio::time::timeout(timeout, socket.flush())
-        .await
-        .map_err(|_| ())?
-        .map_err(|_| ())
-}
-
-fn record_message(
-    runtime: &WebProcessRuntime,
-    trace: Option<&TraceWebSocketContext>,
-    direction: TraceDirection,
-    message_type: &'static str,
-    payload: &[u8],
-    started: Instant,
-) {
-    let Some(trace) = trace else {
-        return;
-    };
-    runtime.trace().record_websocket_message(
-        trace,
-        direction,
-        message_type,
-        payload,
-        started.elapsed().as_micros().min(u128::from(u64::MAX)) as u64,
-    );
-}

src/web/http/websocket/driver/io.rs

@@ -0,0 +1,190 @@
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+
+use futures_util::{SinkExt, StreamExt};
+use tokio_tungstenite::tungstenite::protocol::Message;
+use tokio_util::sync::CancellationToken;
+
+use super::CarrierSocket;
+use crate::web::manager::{ManagerError, WebProcessRuntime, WebSocketBudgetLease};
+use crate::web::session::{WebSession, WebSocketLaneReservation};
+use crate::web::trace::{TraceDirection, TraceWebSocketContext};
+
+pub(super) async fn read_message(
+    socket: &mut CarrierSocket,
+    runtime: &Arc<WebProcessRuntime>,
+    owner: crate::web::manager::ProfileKey,
+    cancellation: &CancellationToken,
+    retained_budget: &mut Option<WebSocketBudgetLease>,
+    maximum: usize,
+    backpressure_timeout: Duration,
+) -> Result<(Message, Option<WebSocketBudgetLease>), ()> {
+    tokio::select! {
+        _ = cancellation.cancelled() => return Err(()),
+        ready = socket.get_ref().readable() => ready.map_err(|_| ())?,
+    }
+    if retained_budget.is_none() {
+        *retained_budget =
+            Some(reserve_data(runtime, owner, maximum, cancellation, backpressure_timeout).await?);
+    }
+    let message = tokio::select! {
+        _ = cancellation.cancelled() => return Err(()),
+        message = socket.next() => message.ok_or(())?.map_err(|_| ())?,
+    };
+    if socket.get_ref().websocket_fragmented_message() {
+        return Ok((message, None));
+    }
+    let mut budget = retained_budget.take().ok_or(())?;
+    budget.shrink_to(message.len());
+    Ok((message, Some(budget)))
+}
+
+pub(super) async fn reserve_data(
+    runtime: &Arc<WebProcessRuntime>,
+    owner: crate::web::manager::ProfileKey,
+    bytes: usize,
+    cancellation: &CancellationToken,
+    timeout: Duration,
+) -> Result<WebSocketBudgetLease, ()> {
+    tokio::time::timeout(timeout, async {
+        loop {
+            if cancellation.is_cancelled() {
+                return Err(());
+            }
+            let notify = runtime.budget_notify();
+            let notified = notify.notified();
+            if let Some(budget) = runtime.try_websocket_data_budget(owner, bytes.max(1)) {
+                return Ok(budget);
+            }
+            tokio::select! {
+                _ = cancellation.cancelled() => return Err(()),
+                _ = notified => {}
+            }
+        }
+    })
+    .await
+    .map_err(|_| ())?
+}
+
+pub(super) async fn process_multiplex(
+    runtime: &Arc<WebProcessRuntime>,
+    session: &Arc<WebSession>,
+    sequence: u64,
+    body: &[u8],
+    cancellation: &CancellationToken,
+    timeout: Duration,
+) -> Result<bool, ()> {
+    retry_backpressure(runtime, cancellation, timeout, || {
+        session.process_websocket_multiplex(sequence, body)
+    })
+    .await
+}
+
+pub(super) async fn process_lane(
+    runtime: &Arc<WebProcessRuntime>,
+    session: &Arc<WebSession>,
+    reservation: &mut WebSocketLaneReservation,
+    sequence: u64,
+    body: &[u8],
+    cancellation: &CancellationToken,
+    timeout: Duration,
+) -> Result<bool, ()> {
+    tokio::time::timeout(timeout, async {
+        loop {
+            if cancellation.is_cancelled() {
+                return Err(());
+            }
+            let notify = runtime.budget_notify();
+            let notified = notify.notified();
+            match session.process_websocket_lane(reservation, sequence, body) {
+                Ok(progressed) => return Ok(progressed),
+                Err(ManagerError::Backpressure) => {}
+                Err(_) => return Err(()),
+            }
+            tokio::select! {
+                _ = cancellation.cancelled() => return Err(()),
+                _ = notified => {}
+            }
+        }
+    })
+    .await
+    .map_err(|_| ())?
+}
+
+async fn retry_backpressure<F, T>(
+    runtime: &Arc<WebProcessRuntime>,
+    cancellation: &CancellationToken,
+    timeout: Duration,
+    mut operation: F,
+) -> Result<T, ()>
+where
+    F: FnMut() -> Result<T, ManagerError>,
+{
+    tokio::time::timeout(timeout, async {
+        loop {
+            if cancellation.is_cancelled() {
+                return Err(());
+            }
+            let notify = runtime.budget_notify();
+            let notified = notify.notified();
+            match operation() {
+                Ok(value) => return Ok(value),
+                Err(ManagerError::Backpressure) => {}
+                Err(_) => return Err(()),
+            }
+            tokio::select! {
+                _ = cancellation.cancelled() => return Err(()),
+                _ = notified => {}
+            }
+        }
+    })
+    .await
+    .map_err(|_| ())?
+}
+
+pub(super) async fn send(
+    socket: &mut CarrierSocket,
+    message: Message,
+    cancellation: &CancellationToken,
+    timeout: Duration,
+) -> Result<(), ()> {
+    tokio::select! {
+        _ = cancellation.cancelled() => Err(()),
+        result = tokio::time::timeout(timeout, socket.send(message)) => {
+            result.map_err(|_| ())?.map_err(|_| ())
+        }
+    }
+}
+
+pub(super) async fn flush(
+    socket: &mut CarrierSocket,
+    cancellation: &CancellationToken,
+    timeout: Duration,
+) -> Result<(), ()> {
+    tokio::select! {
+        _ = cancellation.cancelled() => Err(()),
+        result = tokio::time::timeout(timeout, socket.flush()) => {
+            result.map_err(|_| ())?.map_err(|_| ())
+        }
+    }
+}
+
+pub(super) fn record_message(
+    runtime: &WebProcessRuntime,
+    trace: Option<&TraceWebSocketContext>,
+    direction: TraceDirection,
+    message_type: &'static str,
+    payload: &[u8],
+    started: Instant,
+) {
+    let Some(trace) = trace else {
+        return;
+    };
+    runtime.trace().record_websocket_message(
+        trace,
+        direction,
+        message_type,
+        payload,
+        started.elapsed().as_micros().min(u128::from(u64::MAX)) as u64,
+    );
+}

src/web/http/websocket/driver/lane.rs

@@ -0,0 +1,265 @@
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+
+use bytes::Bytes;
+use tokio_tungstenite::tungstenite::protocol::Message;
+use tokio_util::sync::CancellationToken;
+
+use super::CarrierSocket;
+use super::io::{flush, process_lane, read_message, record_message, reserve_data, send};
+use crate::web::manager::{WebProcessRuntime, WebSocketBudgetLease, WebSocketConnection};
+use crate::web::session::{WebSession, WebSocketLaneReservation};
+use crate::web::trace::{TraceDirection, TraceWebSocketContext};
+
+#[allow(clippy::too_many_arguments)]
+pub(super) async fn run_lane(
+    socket: &mut CarrierSocket,
+    runtime: &Arc<WebProcessRuntime>,
+    session: &Arc<WebSession>,
+    connection: &WebSocketConnection,
+    reservation: &mut WebSocketLaneReservation,
+    cancellation: CancellationToken,
+    trace: Option<&TraceWebSocketContext>,
+    acknowledge_commit: bool,
+) -> Result<(), ()> {
+    let mut sequence = 1u64;
+    let mut cursor = 0u64;
+    // Lane reads use the same cancellation-safe fragmented-message ownership.
+    let mut read_budget = None;
+    let liveness_interval = connection.liveness_interval();
+    let mut next_ping = Instant::now() + liveness_interval;
+    let open_deadline =
+        Instant::now() + Duration::from_secs(session.timeouts().websocket_open_secs);
+    let backpressure_timeout = Duration::from_secs(session.timeouts().websocket_backpressure_secs);
+    let write_timeout = Duration::from_secs(session.timeouts().websocket_write_secs);
+    let maximum_message = session.limits().carrier_batch_bytes;
+    let mut active = false;
+    loop {
+        let down = session.poll_down_lane(reservation.lane_id(), cursor);
+        tokio::pin!(down);
+        let event = tokio::select! {
+            _ = cancellation.cancelled() => return Err(()),
+            _ = tokio::time::sleep_until(open_deadline.into()), if !active => return Err(()),
+            _ = tokio::time::sleep_until(next_ping.into()) => DriverEvent::Liveness,
+            incoming = read_message(
+                socket,
+                runtime,
+                session.profile_key(),
+                &cancellation,
+                &mut read_budget,
+                maximum_message,
+                backpressure_timeout,
+            ) => {
+                DriverEvent::Incoming(incoming?)
+            }
+            down = &mut down => DriverEvent::Down(down.map_err(|_| ())?),
+        };
+        match event {
+            DriverEvent::Incoming((message, _budget)) => match message {
+                Message::Binary(body) => {
+                    let started = Instant::now();
+                    let result = process_lane(
+                        runtime,
+                        session,
+                        reservation,
+                        sequence,
+                        &body,
+                        &cancellation,
+                        backpressure_timeout,
+                    )
+                    .await;
+                    record_message(
+                        runtime,
+                        trace,
+                        TraceDirection::Request,
+                        "binary",
+                        &body,
+                        started,
+                    );
+                    let progressed = result?;
+                    if acknowledge_commit && sequence == 1 {
+                        if !session.needs_websocket_commit_ack(connection.id()) {
+                            return Err(());
+                        }
+                        let started = Instant::now();
+                        if send(
+                            socket,
+                            Message::Binary(Bytes::new()),
+                            &cancellation,
+                            write_timeout,
+                        )
+                        .await
+                        .is_err()
+                        {
+                            session.close();
+                            return Err(());
+                        }
+                        record_message(
+                            runtime,
+                            trace,
+                            TraceDirection::Response,
+                            "carrier-ack",
+                            &[],
+                            started,
+                        );
+                        if !session.websocket_commit_ack_written(connection.id()) {
+                            session.close();
+                            return Err(());
+                        }
+                    } else if acknowledge_commit && sequence > 1 && progressed {
+                        if !session.websocket_peer_after_commit_ack(connection.id()) {
+                            return Err(());
+                        }
+                    }
+                    if !active && progressed {
+                        if !connection.mark_active() {
+                            return Err(());
+                        }
+                        active = true;
+                    }
+                    sequence = sequence.checked_add(1).ok_or(())?;
+                    connection.mark_peer_activity();
+                    next_ping = Instant::now() + liveness_interval;
+                }
+                Message::Pong(payload) => {
+                    record_message(
+                        runtime,
+                        trace,
+                        TraceDirection::Request,
+                        "pong",
+                        &payload,
+                        Instant::now(),
+                    );
+                    connection.mark_peer_activity();
+                    next_ping = Instant::now() + liveness_interval;
+                }
+                Message::Ping(payload) => {
+                    let started = Instant::now();
+                    flush(socket, &cancellation, write_timeout).await?;
+                    record_message(
+                        runtime,
+                        trace,
+                        TraceDirection::Request,
+                        "ping",
+                        &payload,
+                        started,
+                    );
+                    record_message(
+                        runtime,
+                        trace,
+                        TraceDirection::Response,
+                        "pong",
+                        &payload,
+                        started,
+                    );
+                    connection.mark_peer_activity();
+                    next_ping = Instant::now() + liveness_interval;
+                }
+                Message::Close(_) => {
+                    record_message(
+                        runtime,
+                        trace,
+                        TraceDirection::Request,
+                        "close",
+                        &[],
+                        Instant::now(),
+                    );
+                    return Ok(());
+                }
+                Message::Text(text) => {
+                    record_message(
+                        runtime,
+                        trace,
+                        TraceDirection::Request,
+                        "text",
+                        text.as_bytes(),
+                        Instant::now(),
+                    );
+                    return Err(());
+                }
+                Message::Frame(_) => return Err(()),
+            },
+            DriverEvent::Down(result) => {
+                if result.lane_closed {
+                    return Ok(());
+                }
+                if result.body.is_empty() {
+                    let started = Instant::now();
+                    send(
+                        socket,
+                        Message::Ping(Bytes::new()),
+                        &cancellation,
+                        write_timeout,
+                    )
+                    .await?;
+                    record_message(
+                        runtime,
+                        trace,
+                        TraceDirection::Response,
+                        "ping",
+                        &[],
+                        started,
+                    );
+                    next_ping = Instant::now() + liveness_interval;
+                } else {
+                    let _budget = reserve_data(
+                        runtime,
+                        session.profile_key(),
+                        result.body.len(),
+                        &cancellation,
+                        backpressure_timeout,
+                    )
+                    .await?;
+                    let body = result.body;
+                    let started = Instant::now();
+                    if trace.is_some() {
+                        send(
+                            socket,
+                            Message::Binary(body.clone()),
+                            &cancellation,
+                            write_timeout,
+                        )
+                        .await?;
+                        record_message(
+                            runtime,
+                            trace,
+                            TraceDirection::Response,
+                            "binary",
+                            &body,
+                            started,
+                        );
+                    } else {
+                        send(socket, Message::Binary(body), &cancellation, write_timeout).await?;
+                    }
+                    connection.mark_progress();
+                }
+                cursor = result.next_cursor;
+            }
+            DriverEvent::Liveness => {
+                let started = Instant::now();
+                send(
+                    socket,
+                    Message::Ping(Bytes::new()),
+                    &cancellation,
+                    write_timeout,
+                )
+                .await?;
+                record_message(
+                    runtime,
+                    trace,
+                    TraceDirection::Response,
+                    "ping",
+                    &[],
+                    started,
+                );
+                next_ping = Instant::now() + liveness_interval;
+            }
+        }
+    }
+}
+
+enum DriverEvent {
+    Incoming((Message, Option<WebSocketBudgetLease>)),
+    Down(crate::web::session::PollResult),
+    Liveness,
+}

src/web/http/websocket/tests.rs

@@ -14,8 +14,10 @@ use tokio_util::sync::CancellationToken;
 
 use crate::maestro::generation::{RuntimeGeneration, test_runtime_generation};
 use crate::web::frame::{self, FrameType};
-use crate::web::http::tests::runtime_config;
-use crate::web::manager::WebProcessRuntime;
+use crate::web::http::tests::{negotiation_runtime_config, runtime_config};
+use crate::web::manager::{
+    CarrierCapabilities, CarrierClientClass, CarrierFailure, CarrierRequest, WebProcessRuntime,
+};
 
 fn request(protocol: &str) -> Request<()> {
     Request::builder()
@@ -39,6 +41,14 @@ fn canonical_multiplex_and_lane_protocols_are_accepted() {
 
     let lane = parse_upgrade(&request(&format!("tproxy-lane-v1.{token}.16777215"))).unwrap();
     assert!(matches!(lane.carrier, ParsedCarrier::Lane(16_777_215)));
+
+    let automatic = parse_upgrade(&request(&format!("tproxy-auto-v1.{token}"))).unwrap();
+    assert!(automatic.acknowledge_commit);
+    let automatic_lane =
+        parse_upgrade(&request(&format!("tproxy-auto-lane-v1.{token}.7"))).unwrap();
+    assert!(matches!(automatic_lane.carrier, ParsedCarrier::Lane(7)));
+    assert!(automatic_lane.acknowledge_commit);
+    assert!(!multiplex.acknowledge_commit);
 }
 
 #[test]
@@ -92,7 +102,20 @@ fn live_runtime(carrier: WebCarrier) -> LiveRuntime {
 }
 
 fn live_runtime_with_long_poll(carrier: WebCarrier, long_poll_secs: u64) -> LiveRuntime {
-    let mut config = runtime_config([31; 32], carrier);
+    live_runtime_from_config(runtime_config([31; 32], carrier), long_poll_secs)
+}
+
+fn live_negotiation_runtime(carrier: WebCarrier, carriers: Arc<[WebCarrier]>) -> LiveRuntime {
+    live_runtime_from_config(
+        negotiation_runtime_config([31; 32], carrier, false, carriers),
+        1,
+    )
+}
+
+fn live_runtime_from_config(
+    mut config: crate::config::ProxyConfig,
+    long_poll_secs: u64,
+) -> LiveRuntime {
     config.web.timeouts.long_poll_secs = long_poll_secs;
     config.web.timeouts.websocket_write_secs = 2;
     config.web.timeouts.websocket_backpressure_secs = 2;
@@ -105,6 +128,49 @@ fn live_runtime_with_long_poll(carrier: WebCarrier, long_poll_secs: u64) -> Live
     }
 }
 
+fn create_automatic_session(
+    runtime: &Arc<WebProcessRuntime>,
+) -> (TokenHash, Bytes, String, TokenHash) {
+    let profile = runtime
+        .active_generation()
+        .config()
+        .web
+        .runtime
+        .as_ref()
+        .unwrap()
+        .profiles[0]
+        .clone();
+    let client_ip = "192.0.2.10".parse().unwrap();
+    let bootstrap = runtime.issue_bootstrap(profile, client_ip).unwrap().token;
+    let raw = base64::engine::general_purpose::URL_SAFE_NO_PAD
+        .decode(&bootstrap)
+        .unwrap();
+    let bootstrap_hash = Sha256::digest(raw).into();
+    let hello = frame::encode(FrameType::Hello, 0, &[1]);
+    let session = runtime
+        .create_session(
+            bootstrap_hash,
+            "proxy.example.com",
+            client_ip,
+            &hello,
+            CarrierRequest::automatic(
+                CarrierClientClass::Bridge,
+                CarrierCapabilities::all(),
+                1,
+                None,
+                [9; 32],
+            ),
+            false,
+        )
+        .unwrap()
+        .token;
+    let raw = base64::engine::general_purpose::URL_SAFE_NO_PAD
+        .decode(&session)
+        .unwrap();
+    let session_hash = Sha256::digest(raw).into();
+    (bootstrap_hash, hello, session, session_hash)
+}
+
 fn create_session(runtime: &Arc<WebProcessRuntime>) -> (String, TokenHash) {
     let profile = runtime
         .active_generation()
@@ -123,7 +189,14 @@ fn create_session(runtime: &Arc<WebProcessRuntime>) -> (String, TokenHash) {
     let bootstrap_hash = Sha256::digest(raw).into();
     let hello = frame::encode(FrameType::Hello, 0, &[1]);
     let session = runtime
-        .create_session(bootstrap_hash, "proxy.example.com", client_ip, &hello)
+        .create_session(
+            bootstrap_hash,
+            "proxy.example.com",
+            client_ip,
+            &hello,
+            CarrierRequest::legacy([0; 32]),
+            false,
+        )
         .unwrap()
         .token;
     let raw = base64::engine::general_purpose::URL_SAFE_NO_PAD
@@ -309,3 +382,106 @@ async fn malformed_websocket_lane_closes_only_that_lane() {
     let _ = second.close(None).await;
     live.shutdown().await;
 }
+
+#[tokio::test]
+async fn automatic_websocket_carriers_commit_after_acknowledged_peer_progress() {
+    for carrier in [WebCarrier::Websocket, WebCarrier::WebsocketLanes] {
+        let live = live_negotiation_runtime(carrier, Arc::from([carrier]));
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let (_, _, session, session_hash) = create_automatic_session(&live.runtime);
+        let protocol = match carrier {
+            WebCarrier::Websocket => format!("tproxy-auto-v1.{session}"),
+            WebCarrier::WebsocketLanes => format!("tproxy-auto-lane-v1.{session}.7"),
+            _ => unreachable!(),
+        };
+        let mut socket = upgrade(&listener, &live.runtime, &protocol).await;
+        socket
+            .send(Message::Binary(frame::encode(FrameType::Open, 7, &[])))
+            .await
+            .unwrap();
+        let acknowledgement = tokio::time::timeout(Duration::from_secs(2), socket.next())
+            .await
+            .unwrap()
+            .unwrap()
+            .unwrap();
+        assert_eq!(acknowledgement, Message::Binary(Bytes::new()));
+        assert!(
+            live.runtime
+                .get_session(session_hash, "proxy.example.com")
+                .unwrap()
+                .is_carrier_committed()
+        );
+        socket
+            .send(Message::Binary(frame::encode(
+                FrameType::Window,
+                7,
+                &frame::window_payload(1),
+            )))
+            .await
+            .unwrap();
+        socket
+            .send(Message::Ping(Bytes::from_static(b"commit")))
+            .await
+            .unwrap();
+        loop {
+            let message = tokio::time::timeout(Duration::from_secs(2), socket.next())
+                .await
+                .unwrap()
+                .unwrap()
+                .unwrap();
+            if message == Message::Pong(Bytes::from_static(b"commit")) {
+                break;
+            }
+        }
+        assert!(
+            live.runtime
+                .get_session(session_hash, "proxy.example.com")
+                .unwrap()
+                .is_carrier_committed()
+        );
+
+        let _ = socket.close(None).await;
+        live.shutdown().await;
+    }
+}
+
+#[tokio::test]
+async fn failed_automatic_multiplex_socket_remains_supersedable() {
+    let live = live_negotiation_runtime(
+        WebCarrier::Https,
+        Arc::from([WebCarrier::Websocket, WebCarrier::Https]),
+    );
+    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let (bootstrap_hash, hello, session, session_hash) = create_automatic_session(&live.runtime);
+    let protocol = format!("tproxy-auto-v1.{session}");
+    let mut socket = upgrade(&listener, &live.runtime, &protocol).await;
+    socket.close(None).await.unwrap();
+    tokio::time::sleep(Duration::from_millis(200)).await;
+    assert!(
+        live.runtime
+            .get_session(session_hash, "proxy.example.com")
+            .is_ok()
+    );
+
+    let replacement = live
+        .runtime
+        .create_session(
+            bootstrap_hash,
+            "proxy.example.com",
+            "192.0.2.10".parse().unwrap(),
+            &hello,
+            CarrierRequest::automatic(
+                CarrierClientClass::Bridge,
+                CarrierCapabilities::all(),
+                2,
+                Some(CarrierFailure::Upgrade),
+                [9; 32],
+            ),
+            false,
+        )
+        .unwrap();
+    assert_eq!(replacement.carrier, WebCarrier::Https);
+    assert_eq!(replacement.attempt, Some(2));
+
+    live.shutdown().await;
+}

src/web/manager.rs

@@ -16,8 +16,19 @@ use crate::web::trace::WebTraceStore;
 
 // Credential maps, quotas, and token-bucket helpers remain private to the manager.
 mod state;
+// Carrier attempt metadata remains explicit and independent from HTTP parsing.
+mod negotiation;
+// Bounded process-local carrier evidence is isolated from session registries.
+#[path = "manager/carrier_learning.rs"]
+mod learning;
 // Bootstrap credentials and idempotent session creation are isolated from queue accounting.
 mod credentials;
+// First-session admission and bounded carrier replacement share one state machine.
+mod session_creation;
+// Session admission remains separate from stream tuple ownership.
+mod session_admission;
+// Carrier commit, health, and conflict echoes share one outcome publication path.
+mod carrier_outcome;
 // Stream admission and synthetic tuple ownership are process-scoped.
 mod admission;
 // Shutdown and expiry work remain outside request-path coordination.
@@ -28,7 +39,10 @@ mod budget;
 mod websocket;
 pub(crate) use budget::WebSocketBudgetLease;
 use budget::{WebDataBudget, WebSocketBudgetClass};
-use state::ManagerState;
+pub(crate) use negotiation::{
+    CarrierCapabilities, CarrierClientClass, CarrierFailure, CarrierLearningContext, CarrierRequest,
+};
+use state::{ManagerState, StreamAdmissionState};
 pub(crate) use websocket::{WebSocketConnection, WebSocketKind};
 
 const TOKEN_BYTES: usize = 32;
@@ -52,16 +66,55 @@ pub(crate) enum ManagerError {
     Protocol,
     /// The operation conflicts with another in-flight operation.
     Concurrent,
+    /// An authenticated attempt chain is already committed.
+    Committed,
     /// The process or session has stopped accepting work.
     Closed,
 }
 
+impl ManagerError {
+    /// Returns the stable non-sensitive failure token used by WEB diagnostics.
+    pub(crate) const fn as_str(self) -> &'static str {
+        match self {
+            Self::Authentication => "authentication",
+            Self::Backpressure => "backpressure",
+            Self::Limit => "limit",
+            Self::Protocol => "protocol",
+            Self::Concurrent => "concurrent",
+            Self::Committed => "committed",
+            Self::Closed => "closed",
+        }
+    }
+}
+
 /// Successful idempotent session creation result.
 pub(crate) struct CreateResult {
     /// Opaque bearer token for the created or replayed session.
     pub(crate) token: String,
     /// Carrier frozen into the created or replayed session.
     pub(crate) carrier: WebCarrier,
+    /// One-based carrier attempt echoed only for negotiated sessions.
+    pub(crate) attempt: Option<u8>,
+    /// Effective frozen candidate count on the first automatic response.
+    pub(crate) candidate_count: Option<u8>,
+    /// Cumulative final chain deadline on the first automatic response.
+    pub(crate) deadline_secs: Option<u64>,
+    /// Actual attempt-chain phase echoed for automatic sessions.
+    pub(crate) carrier_state: Option<&'static str>,
+}
+
+/// Authenticated non-secret attempt-chain metadata returned with a conflict.
+pub(crate) struct CarrierEcho {
+    /// Carrier frozen into the current committed attempt.
+    pub(crate) carrier: WebCarrier,
+    /// One-based current attempt.
+    pub(crate) attempt: u8,
+    /// Frozen supported candidate count.
+    pub(crate) candidate_count: u8,
+    /// Frozen cumulative final deadline.
+    pub(crate) deadline_secs: u64,
+    /// Actual current chain phase.
+    pub(crate) state: &'static str,
 }
 
 /// Successful bridge bootstrap issuance result.
@@ -78,9 +131,12 @@ pub(crate) struct WebProcessRuntime {
     trace: Arc<WebTraceStore>,
     limits: WebLimitsConfig,
     state: Mutex<ManagerState>,
+    stream_admission: Mutex<StreamAdmissionState>,
+    learning: Mutex<learning::CarrierLearning>,
     http_connections: Arc<Semaphore>,
     http_handlers: Arc<Semaphore>,
     lane_polls: Arc<Semaphore>,
+    lane_aux_polls: Arc<Semaphore>,
     body_readers: Arc<Semaphore>,
     body_bytes: Arc<Semaphore>,
     stream_handshakes: Arc<Semaphore>,
@@ -115,16 +171,28 @@ impl WebProcessRuntime {
         active_runtime: Arc<ArcSwap<RuntimeGeneration>>,
         trace: Arc<WebTraceStore>,
     ) -> Arc<Self> {
-        let limits = active_runtime.load().config().web.limits.clone();
+        let config = active_runtime.load().config();
+        let limits = config.web.limits.clone();
+        let learning_capacity = limits.max_carrier_learning_entries;
+        let mut carrier_learning = learning::CarrierLearning::new(learning_capacity);
+        let _ = carrier_learning.apply_policy(
+            std::time::Instant::now(),
+            config.web.carrier_negotiation_enabled() && config.web.carrier_learning,
+            config.web.carrier_negotiation_aggressiveness,
+            Duration::from_secs(config.web.timeouts.carrier_learning_secs),
+        );
         let websocket_connections = limits
             .max_http_connections
             .saturating_sub(limits.websocket_http_connection_reserve);
+        let lane_poll_limit = limits.max_http_handlers / 2;
+        let lane_aux_poll_limit = (lane_poll_limit / 2).max(1);
         let runtime = Arc::new(Self {
             active_runtime,
             trace,
             http_connections: Arc::new(Semaphore::new(limits.max_http_connections)),
             http_handlers: Arc::new(Semaphore::new(limits.max_http_handlers)),
-            lane_polls: Arc::new(Semaphore::new((limits.max_http_handlers / 2).max(1))),
+            lane_polls: Arc::new(Semaphore::new(lane_poll_limit)),
+            lane_aux_polls: Arc::new(Semaphore::new(lane_aux_poll_limit)),
             body_readers: Arc::new(Semaphore::new(limits.max_body_readers)),
             body_bytes: Arc::new(Semaphore::new(limits.max_body_bytes_global)),
             stream_handshakes: Arc::new(Semaphore::new(limits.max_stream_handshakes)),
@@ -136,6 +204,8 @@ impl WebProcessRuntime {
             data_budget: WebDataBudget::new(limits.clone()),
             limits,
             state: Mutex::new(ManagerState::default()),
+            stream_admission: Mutex::new(StreamAdmissionState::default()),
+            learning: Mutex::new(carrier_learning),
             shutdown: CancellationToken::new(),
             tasks: TaskTracker::new(),
             sessions_created: AtomicU64::new(0),
@@ -197,8 +267,13 @@ impl WebProcessRuntime {
     }
 
     /// Reserves one parked lane poll without exhausting all HTTP handlers.
-    pub(crate) fn try_lane_poll(&self) -> Option<OwnedSemaphorePermit> {
-        let permit = Arc::clone(&self.lane_polls).try_acquire_owned().ok();
+    pub(crate) fn try_lane_poll(&self, auxiliary: bool) -> Option<OwnedSemaphorePermit> {
+        let slots = if auxiliary {
+            &self.lane_aux_polls
+        } else {
+            &self.lane_polls
+        };
+        let permit = Arc::clone(slots).try_acquire_owned().ok();
         if permit.is_none() {
             self.record_limit_hit();
         }
@@ -251,6 +326,18 @@ impl WebProcessRuntime {
         Some((reader, body))
     }
 
+    /// Reserves transient bytes while one downlink batch replaces queued frames.
+    pub(crate) fn try_downlink_staging_budget(&self, bytes: usize) -> Option<OwnedSemaphorePermit> {
+        let bytes = u32::try_from(bytes).ok()?;
+        let permit = Arc::clone(&self.body_bytes)
+            .try_acquire_many_owned(bytes)
+            .ok();
+        if permit.is_none() {
+            self.record_limit_hit();
+        }
+        permit
+    }
+
     /// Reserves bounded process-wide queue capacity for data or control traffic.
     pub(crate) fn try_reserve_pending(
         &self,
@@ -307,25 +394,30 @@ impl WebProcessRuntime {
     }
 
     /// Admits one WebSocket with owner-first bounded replacement.
+    #[allow(clippy::too_many_arguments)]
     pub(crate) async fn admit_websocket(
         self: &Arc<Self>,
         owner: ProfileKey,
         session_id: u64,
+        session_hash: TokenHash,
         client_ip: IpAddr,
         kind: WebSocketKind,
         base_bytes: usize,
         liveness_interval: Duration,
         eviction_timeout: Duration,
+        parent_cancellation: CancellationToken,
     ) -> Result<WebSocketConnection, ManagerError> {
         websocket::admit(
             self,
             owner,
             session_id,
+            session_hash,
             client_ip,
             kind,
             base_bytes,
             liveness_interval,
             eviction_timeout,
+            parent_cancellation,
         )
         .await
     }

src/web/manager/admission.rs

@@ -15,7 +15,7 @@ impl WebProcessRuntime {
         public_addr: SocketAddr,
     ) -> Option<u16> {
         let now = Instant::now();
-        let mut state = self.state.lock();
+        let mut state = self.stream_admission.lock();
         if state.closed
             || state.streams_live >= self.limits.max_streams_global
             || state
@@ -54,7 +54,7 @@ impl WebProcessRuntime {
         public_addr: SocketAddr,
         peer_port: u16,
     ) {
-        let mut state = self.state.lock();
+        let mut state = self.stream_admission.lock();
         if !release_stream_port(&mut state, client_ip, public_addr, peer_port) {
             return;
         }

src/web/manager/budget.rs

@@ -163,7 +163,6 @@ impl WebDataBudget {
         }
         remove_owner(&mut state.owner_bytes, owner, bytes);
         drop(state);
-        self.pressured.store(false, Ordering::Release);
         self.notify.notify_waiters();
     }
 
@@ -217,6 +216,10 @@ impl WebDataBudget {
         self.pressured.swap(false, Ordering::AcqRel)
     }
 
+    pub(super) fn restore_pressure(&self) {
+        self.pressured.store(true, Ordering::Release);
+    }
+
     pub(super) fn owner_usage(&self, owner: ProfileKey) -> usize {
         self.state
             .lock()
@@ -259,7 +262,6 @@ impl WebDataBudget {
         state.websocket_bytes = state.websocket_bytes.saturating_sub(bytes);
         remove_owner(&mut state.owner_bytes, owner, bytes);
         drop(state);
-        self.pressured.store(false, Ordering::Release);
         self.notify.notify_waiters();
     }
 }

src/web/manager/carrier_learning.rs

@@ -0,0 +1,467 @@
+use std::collections::{HashMap, VecDeque};
+use std::net::IpAddr;
+use std::time::{Duration, Instant};
+
+use sha2::{Digest, Sha256};
+
+use super::ProfileKey;
+use super::negotiation::{CarrierClientClass, CarrierLearningContext};
+use crate::config::{WebCarrier, WebCarrierNegotiationAggressiveness};
+
+const PROFILE_WEIGHT: i16 = 32;
+const USER_AGENT_WEIGHT: i16 = 32;
+const IP_WEIGHT: i16 = 1;
+const SCORE_MIN: i8 = -8;
+const SCORE_MAX: i8 = 8;
+const MAX_COHORTS: usize = 4;
+const PRUNE_ENTRIES_PER_TICK: usize = 64;
+const COHORT_CONTEXT: &[u8] = b"telemt-web-carrier-cohort-v1\0";
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+enum EvidenceKey {
+    Profile(ProfileKey),
+    UserAgent(ProfileKey, CarrierClientClass, [u8; 32]),
+    Ip(ProfileKey, IpAddr),
+}
+
+#[derive(Clone, Copy, Default)]
+struct Bucket {
+    slot: u64,
+    valid: bool,
+    scores: [i8; 4],
+    outcomes: u8,
+    cohorts: [Option<[u8; 32]>; MAX_COHORTS],
+}
+
+impl Bucket {
+    fn reset(&mut self, slot: u64) {
+        *self = Self {
+            slot,
+            valid: true,
+            ..Self::default()
+        };
+    }
+
+    fn update(&mut self, deltas: [i8; 4], cohort: Option<[u8; 32]>) {
+        for (score, delta) in self.scores.iter_mut().zip(deltas) {
+            *score = score.saturating_add(delta).clamp(SCORE_MIN, SCORE_MAX);
+        }
+        self.outcomes = self.outcomes.saturating_add(1);
+        if let Some(cohort) = cohort
+            && !self.cohorts.contains(&Some(cohort))
+            && let Some(slot) = self.cohorts.iter_mut().find(|slot| slot.is_none())
+        {
+            *slot = Some(cohort);
+        }
+    }
+}
+
+struct Evidence {
+    insertion_sequence: u64,
+    buckets: [Bucket; 2],
+}
+
+impl Evidence {
+    fn new(insertion_sequence: u64) -> Self {
+        Self {
+            insertion_sequence,
+            buckets: [Bucket::default(), Bucket::default()],
+        }
+    }
+
+    fn update(&mut self, slot: u64, deltas: [i8; 4], cohort: Option<[u8; 32]>) {
+        let index = slot as usize % self.buckets.len();
+        if !self.buckets[index].valid || self.buckets[index].slot != slot {
+            self.buckets[index].reset(slot);
+        }
+        self.buckets[index].update(deltas, cohort);
+    }
+
+    fn aggregate(&self, slot: u64) -> Aggregate {
+        let mut aggregate = Aggregate::default();
+        for bucket in &self.buckets {
+            if !bucket.valid || (bucket.slot != slot && bucket.slot.saturating_add(1) != slot) {
+                continue;
+            }
+            aggregate.outcomes = aggregate.outcomes.saturating_add(bucket.outcomes);
+            for (score, value) in aggregate.scores.iter_mut().zip(bucket.scores) {
+                *score = score.saturating_add(value).clamp(SCORE_MIN, SCORE_MAX);
+            }
+            for cohort in bucket.cohorts.iter().flatten() {
+                if !aggregate.cohorts.contains(&Some(*cohort))
+                    && let Some(target) = aggregate.cohorts.iter_mut().find(|slot| slot.is_none())
+                {
+                    *target = Some(*cohort);
+                }
+            }
+        }
+        aggregate
+    }
+
+    fn is_live(&self, slot: u64) -> bool {
+        self.buckets.iter().any(|bucket| {
+            bucket.valid && (bucket.slot == slot || bucket.slot.saturating_add(1) == slot)
+        })
+    }
+}
+
+#[derive(Default)]
+struct Aggregate {
+    scores: [i8; 4],
+    outcomes: u8,
+    cohorts: [Option<[u8; 32]>; MAX_COHORTS],
+}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+struct LearningPolicy {
+    enabled: bool,
+    aggressiveness: WebCarrierNegotiationAggressiveness,
+    lifetime: Duration,
+}
+
+#[derive(Clone, Copy)]
+struct Thresholds {
+    user_agent: u8,
+    ip: Option<u8>,
+    profile_outcomes: u8,
+    profile_cohorts: usize,
+}
+
+impl Thresholds {
+    fn for_aggressiveness(value: WebCarrierNegotiationAggressiveness) -> Self {
+        match value {
+            WebCarrierNegotiationAggressiveness::Conservative => Self {
+                user_agent: 3,
+                ip: None,
+                profile_outcomes: 8,
+                profile_cohorts: 4,
+            },
+            WebCarrierNegotiationAggressiveness::Balanced => Self {
+                user_agent: 2,
+                ip: Some(3),
+                profile_outcomes: 6,
+                profile_cohorts: 3,
+            },
+            WebCarrierNegotiationAggressiveness::Aggressive => Self {
+                user_agent: 1,
+                ip: Some(1),
+                profile_outcomes: 4,
+                profile_cohorts: 2,
+            },
+        }
+    }
+}
+
+/// Process-local bounded two-bucket carrier evidence store.
+pub(super) struct CarrierLearning {
+    entries: HashMap<EvidenceKey, Evidence>,
+    insertion_order: VecDeque<(EvidenceKey, u64)>,
+    capacity: usize,
+    insertion_sequence: u64,
+    epoch: Option<u64>,
+    policy: Option<LearningPolicy>,
+    policy_started_at: Instant,
+}
+
+impl CarrierLearning {
+    /// Creates an empty store under the restart-owned capacity ceiling.
+    pub(super) fn new(capacity: usize) -> Self {
+        Self {
+            entries: HashMap::new(),
+            insertion_order: VecDeque::new(),
+            capacity,
+            insertion_sequence: 1,
+            epoch: Some(0),
+            policy: None,
+            policy_started_at: Instant::now(),
+        }
+    }
+
+    /// Applies hot-reloaded learning policy and returns its outcome epoch.
+    pub(super) fn apply_policy(
+        &mut self,
+        now: Instant,
+        enabled: bool,
+        aggressiveness: WebCarrierNegotiationAggressiveness,
+        lifetime: Duration,
+    ) -> Option<u64> {
+        let policy = LearningPolicy {
+            enabled,
+            aggressiveness,
+            lifetime,
+        };
+        if self.policy != Some(policy) {
+            self.entries.clear();
+            self.insertion_order.clear();
+            if !enabled {
+                self.entries.shrink_to_fit();
+                self.insertion_order.shrink_to_fit();
+            }
+            self.insertion_sequence = 1;
+            self.epoch = self.epoch.and_then(|epoch| epoch.checked_add(1));
+            self.policy = Some(policy);
+            self.policy_started_at = now;
+        }
+        self.epoch
+    }
+
+    /// Returns the current epoch only when the request snapshot matches owner policy.
+    pub(super) fn epoch_for_policy(
+        &self,
+        enabled: bool,
+        aggressiveness: WebCarrierNegotiationAggressiveness,
+        lifetime: Duration,
+    ) -> Option<u64> {
+        (self.policy
+            == Some(LearningPolicy {
+                enabled,
+                aggressiveness,
+                lifetime,
+            }))
+        .then_some(self.epoch)
+        .flatten()
+    }
+
+    /// Ranks supported configured candidates without scanning the evidence store.
+    pub(super) fn rank(
+        &self,
+        now: Instant,
+        configured: &[WebCarrier],
+        request: super::CarrierRequest,
+        profile_key: ProfileKey,
+        client_ip: IpAddr,
+        ip_learning_eligible: bool,
+    ) -> (Vec<WebCarrier>, [i16; 4]) {
+        let Some(policy) = self.policy.filter(|policy| policy.enabled) else {
+            return (supported(configured, request), [0; 4]);
+        };
+        let slot = bucket_slot(self.policy_started_at, now, policy.lifetime);
+        let thresholds = Thresholds::for_aggressiveness(policy.aggressiveness);
+        let profile = self
+            .entries
+            .get(&EvidenceKey::Profile(profile_key))
+            .map(|entry| entry.aggregate(slot));
+        let user_agent = self
+            .entries
+            .get(&EvidenceKey::UserAgent(
+                profile_key,
+                request.class(),
+                request.user_agent_hash(),
+            ))
+            .map(|entry| entry.aggregate(slot));
+        let ip = (ip_learning_eligible && thresholds.ip.is_some())
+            .then(|| self.entries.get(&EvidenceKey::Ip(profile_key, client_ip)))
+            .flatten()
+            .map(|entry| entry.aggregate(slot));
+        let profile_ready = profile.as_ref().is_some_and(|entry| {
+            entry.outcomes >= thresholds.profile_outcomes
+                && entry.cohorts.iter().flatten().count() >= thresholds.profile_cohorts
+        });
+        let user_agent_ready = user_agent
+            .as_ref()
+            .is_some_and(|entry| entry.outcomes >= thresholds.user_agent);
+        let ip_ready = thresholds
+            .ip
+            .is_some_and(|minimum| ip.as_ref().is_some_and(|entry| entry.outcomes >= minimum));
+        let mut scores = [0i16; 4];
+        for carrier in WebCarrier::ALL {
+            let index = carrier.index();
+            if profile_ready {
+                scores[index] += i16::from(profile.as_ref().map_or(0, |value| value.scores[index]))
+                    * PROFILE_WEIGHT;
+            }
+            if user_agent_ready {
+                scores[index] +=
+                    i16::from(user_agent.as_ref().map_or(0, |value| value.scores[index]))
+                        * USER_AGENT_WEIGHT;
+            }
+            if ip_ready {
+                scores[index] +=
+                    i16::from(ip.as_ref().map_or(0, |value| value.scores[index])) * IP_WEIGHT;
+            }
+        }
+        let mut ranked = supported(configured, request);
+        let fallback = configured
+            .last()
+            .copied()
+            .filter(|carrier| request.supports(*carrier));
+        if let Some(fallback) = fallback {
+            ranked.retain(|carrier| *carrier != fallback);
+        }
+        ranked.sort_by_key(|carrier| std::cmp::Reverse(scores[carrier.index()]));
+        if let Some(fallback) = fallback {
+            ranked.push(fallback);
+        }
+        (ranked, scores)
+    }
+
+    /// Applies one complete attempt chain as one atomic evidence sample.
+    pub(super) fn record_chain(
+        &mut self,
+        now: Instant,
+        epoch: u64,
+        context: CarrierLearningContext,
+        failures: &[WebCarrier],
+        winner: WebCarrier,
+    ) {
+        let Some(policy) = self.policy.filter(|policy| policy.enabled) else {
+            return;
+        };
+        if Some(epoch) != self.epoch {
+            return;
+        }
+        let mut deltas = [0i8; 4];
+        let _ = failures;
+        deltas[winner.index()] = deltas[winner.index()].saturating_add(1);
+        let thresholds = Thresholds::for_aggressiveness(policy.aggressiveness);
+        let keys = [
+            Some(EvidenceKey::Profile(context.profile_key)),
+            Some(EvidenceKey::UserAgent(
+                context.profile_key,
+                context.class,
+                context.user_agent_hash,
+            )),
+            (context.ip_learning_eligible && thresholds.ip.is_some())
+                .then_some(EvidenceKey::Ip(context.profile_key, context.client_ip)),
+        ];
+        self.make_room(&keys);
+        let missing = keys
+            .iter()
+            .flatten()
+            .filter(|key| !self.entries.contains_key(key))
+            .count();
+        if self.entries.len().saturating_add(missing) > self.capacity {
+            return;
+        }
+        let slot = bucket_slot(self.policy_started_at, now, policy.lifetime);
+        let cohort = cohort_hash(context);
+        for (index, key) in keys.into_iter().enumerate() {
+            let Some(key) = key else { continue };
+            self.update_key(key, slot, deltas, (index == 0).then_some(cohort));
+        }
+    }
+
+    /// Reclaims a fixed number of entries outside both half-window buckets.
+    pub(super) fn prune(&mut self, now: Instant) {
+        let Some(policy) = self.policy else { return };
+        let slot = bucket_slot(self.policy_started_at, now, policy.lifetime);
+        let budget = self.insertion_order.len().min(PRUNE_ENTRIES_PER_TICK);
+        for _ in 0..budget {
+            let Some((key, sequence)) = self.insertion_order.pop_front() else {
+                break;
+            };
+            let current = self
+                .entries
+                .get(&key)
+                .is_some_and(|entry| entry.insertion_sequence == sequence);
+            if !current {
+                continue;
+            }
+            if self
+                .entries
+                .get(&key)
+                .is_some_and(|entry| entry.is_live(slot))
+            {
+                self.insertion_order.push_back((key, sequence));
+            } else {
+                self.entries.remove(&key);
+            }
+        }
+    }
+
+    fn make_room(&mut self, keys: &[Option<EvidenceKey>; 3]) {
+        let missing = keys
+            .iter()
+            .flatten()
+            .filter(|key| !self.entries.contains_key(key))
+            .count();
+        let mut remaining = self.insertion_order.len();
+        while self.entries.len().saturating_add(missing) > self.capacity && remaining > 0 {
+            remaining -= 1;
+            let Some((oldest, sequence)) = self.insertion_order.pop_front() else {
+                break;
+            };
+            if self
+                .entries
+                .get(&oldest)
+                .is_none_or(|entry| entry.insertion_sequence != sequence)
+            {
+                continue;
+            }
+            if keys.contains(&Some(oldest)) {
+                self.insertion_order.push_back((oldest, sequence));
+                continue;
+            }
+            self.entries.remove(&oldest);
+        }
+    }
+
+    fn update_key(
+        &mut self,
+        key: EvidenceKey,
+        slot: u64,
+        deltas: [i8; 4],
+        cohort: Option<[u8; 32]>,
+    ) {
+        if let Some(entry) = self.entries.get_mut(&key) {
+            entry.update(slot, deltas, cohort);
+            return;
+        }
+        let Some(insertion_sequence) = self.next_insertion_sequence() else {
+            return;
+        };
+        self.entries.insert(key, Evidence::new(insertion_sequence));
+        self.insertion_order.push_back((key, insertion_sequence));
+        if let Some(entry) = self.entries.get_mut(&key) {
+            entry.update(slot, deltas, cohort);
+        }
+    }
+
+    fn next_insertion_sequence(&mut self) -> Option<u64> {
+        let sequence = self.insertion_sequence;
+        self.insertion_sequence = sequence.checked_add(1)?;
+        Some(sequence)
+    }
+}
+
+fn supported(configured: &[WebCarrier], request: super::CarrierRequest) -> Vec<WebCarrier> {
+    configured
+        .iter()
+        .copied()
+        .filter(|carrier| request.supports(*carrier))
+        .collect()
+}
+
+fn bucket_slot(start: Instant, now: Instant, lifetime: Duration) -> u64 {
+    let half = (lifetime / 2).max(Duration::from_nanos(1));
+    let quotient = now.saturating_duration_since(start).as_nanos() / half.as_nanos();
+    quotient.min(u128::from(u64::MAX)) as u64
+}
+
+fn cohort_hash(context: CarrierLearningContext) -> [u8; 32] {
+    let mut digest = Sha256::new();
+    digest.update(COHORT_CONTEXT);
+    digest.update(context.profile_key);
+    digest.update([match context.class {
+        CarrierClientClass::Legacy => 0,
+        CarrierClientClass::Bridge => 1,
+        CarrierClientClass::BrowserHint => 2,
+        CarrierClientClass::Ios => 3,
+    }]);
+    digest.update(context.user_agent_hash);
+    match context.client_ip {
+        IpAddr::V4(address) => {
+            digest.update([4]);
+            digest.update(address.octets());
+        }
+        IpAddr::V6(address) => {
+            digest.update([6]);
+            digest.update(address.octets());
+        }
+    }
+    digest.finalize().into()
+}
+
+#[cfg(test)]
+#[path = "carrier_learning/tests.rs"]
+mod tests;

src/web/manager/carrier_learning/tests.rs

@@ -0,0 +1,222 @@
+use super::*;
+use crate::web::manager::{CarrierCapabilities, CarrierRequest};
+
+fn request(hash: u8) -> CarrierRequest {
+    CarrierRequest::automatic(
+        CarrierClientClass::Bridge,
+        CarrierCapabilities::all(),
+        1,
+        None,
+        [hash; 32],
+    )
+}
+
+fn context(hash: u8) -> CarrierLearningContext {
+    CarrierLearningContext {
+        profile_key: [1; 32],
+        client_ip: IpAddr::V4(std::net::Ipv4Addr::new(192, 0, 2, hash)),
+        class: CarrierClientClass::Bridge,
+        user_agent_hash: [hash; 32],
+        epoch: 1,
+        ip_learning_eligible: true,
+    }
+}
+
+#[test]
+fn policy_epoch_rejects_late_outcomes_and_clears_state() {
+    let now = Instant::now();
+    let mut learning = CarrierLearning::new(6);
+    let epoch = learning
+        .apply_policy(
+            now,
+            true,
+            WebCarrierNegotiationAggressiveness::Aggressive,
+            Duration::from_secs(10),
+        )
+        .unwrap();
+    learning.record_chain(now, epoch, context(1), &[], WebCarrier::Websocket);
+    assert_eq!(learning.entries.len(), 3);
+    let next = learning
+        .apply_policy(
+            now,
+            false,
+            WebCarrierNegotiationAggressiveness::Aggressive,
+            Duration::from_secs(10),
+        )
+        .unwrap();
+    assert_ne!(epoch, next);
+    learning.record_chain(now, epoch, context(1), &[], WebCarrier::Https);
+    assert!(learning.entries.is_empty());
+}
+
+#[test]
+fn aggressive_policy_ranks_one_atomic_chain_sample() {
+    let now = Instant::now();
+    let mut learning = CarrierLearning::new(6);
+    let epoch = learning
+        .apply_policy(
+            now,
+            true,
+            WebCarrierNegotiationAggressiveness::Aggressive,
+            Duration::from_secs(10),
+        )
+        .unwrap();
+    learning.record_chain(now, epoch, context(2), &[], WebCarrier::Websocket);
+    let (ranked, scores) = learning.rank(
+        now,
+        &[
+            WebCarrier::Https,
+            WebCarrier::Websocket,
+            WebCarrier::HttpsLanes,
+        ],
+        request(2),
+        [1; 32],
+        context(2).client_ip,
+        true,
+    );
+    assert_eq!(
+        ranked,
+        [
+            WebCarrier::Websocket,
+            WebCarrier::Https,
+            WebCarrier::HttpsLanes,
+        ]
+    );
+    assert_eq!(scores[WebCarrier::Websocket.index()], 33);
+}
+
+#[test]
+fn two_half_windows_expire_without_sliding_updates() {
+    let start = Instant::now();
+    let mut learning = CarrierLearning::new(6);
+    let epoch = learning
+        .apply_policy(
+            start,
+            true,
+            WebCarrierNegotiationAggressiveness::Aggressive,
+            Duration::from_secs(10),
+        )
+        .unwrap();
+    learning.record_chain(start, epoch, context(3), &[], WebCarrier::Websocket);
+    learning.record_chain(
+        start + Duration::from_secs(6),
+        epoch,
+        context(3),
+        &[],
+        WebCarrier::Websocket,
+    );
+    learning.prune(start + Duration::from_secs(11));
+    assert_eq!(learning.entries.len(), 3);
+    learning.prune(start + Duration::from_secs(16));
+    assert!(learning.entries.is_empty());
+}
+
+#[test]
+fn exhausted_epoch_and_insertion_identifiers_fail_closed() {
+    let now = Instant::now();
+    let mut learning = CarrierLearning::new(3);
+    learning.epoch = Some(u64::MAX);
+    assert_eq!(
+        learning.apply_policy(
+            now,
+            true,
+            WebCarrierNegotiationAggressiveness::Aggressive,
+            Duration::from_secs(10),
+        ),
+        None
+    );
+    learning.record_chain(now, u64::MAX, context(4), &[], WebCarrier::Https);
+    assert!(learning.entries.is_empty());
+
+    learning.epoch = Some(1);
+    learning.insertion_sequence = u64::MAX;
+    learning.record_chain(now, 1, context(4), &[], WebCarrier::Https);
+    assert!(learning.entries.is_empty());
+}
+
+#[test]
+fn client_reported_failures_do_not_create_negative_evidence() {
+    let now = Instant::now();
+    let mut learning = CarrierLearning::new(3);
+    let epoch = learning
+        .apply_policy(
+            now,
+            true,
+            WebCarrierNegotiationAggressiveness::Aggressive,
+            Duration::from_secs(10),
+        )
+        .unwrap();
+    learning.record_chain(
+        now,
+        epoch,
+        context(5),
+        &[WebCarrier::Websocket],
+        WebCarrier::Https,
+    );
+    let (_, scores) = learning.rank(
+        now,
+        &[WebCarrier::Websocket, WebCarrier::HttpsLanes],
+        request(5),
+        [1; 32],
+        context(5).client_ip,
+        true,
+    );
+    assert_eq!(scores[WebCarrier::Websocket.index()], 0);
+}
+
+#[test]
+fn old_new_old_policy_rejects_both_stale_epochs() {
+    let now = Instant::now();
+    let mut learning = CarrierLearning::new(3);
+    let old = learning
+        .apply_policy(
+            now,
+            true,
+            WebCarrierNegotiationAggressiveness::Aggressive,
+            Duration::from_secs(10),
+        )
+        .unwrap();
+    let middle = learning
+        .apply_policy(
+            now,
+            true,
+            WebCarrierNegotiationAggressiveness::Balanced,
+            Duration::from_secs(10),
+        )
+        .unwrap();
+    let current = learning
+        .apply_policy(
+            now,
+            true,
+            WebCarrierNegotiationAggressiveness::Aggressive,
+            Duration::from_secs(10),
+        )
+        .unwrap();
+    assert_ne!(old, middle);
+    assert_ne!(middle, current);
+    assert_ne!(old, current);
+    learning.record_chain(now, old, context(6), &[], WebCarrier::Https);
+    learning.record_chain(now, middle, context(6), &[], WebCarrier::Https);
+    assert!(learning.entries.is_empty());
+    learning.record_chain(now, current, context(6), &[], WebCarrier::Https);
+    assert_eq!(learning.entries.len(), 3);
+}
+
+#[test]
+fn fifo_metadata_stays_within_the_entry_capacity() {
+    let now = Instant::now();
+    let mut learning = CarrierLearning::new(3);
+    let epoch = learning
+        .apply_policy(
+            now,
+            true,
+            WebCarrierNegotiationAggressiveness::Aggressive,
+            Duration::from_secs(10),
+        )
+        .unwrap();
+    for hash in 1..=32 {
+        learning.record_chain(now, epoch, context(hash), &[], WebCarrier::Https);
+        assert!(learning.entries.len() <= 3);
+        assert!(learning.insertion_order.len() <= 3);
+    }
+}

src/web/manager/carrier_outcome.rs

@@ -0,0 +1,161 @@
+use std::net::IpAddr;
+use std::sync::Arc;
+use std::time::Instant;
+
+use super::state::CarrierChainPhase;
+use super::{
+    CarrierClientClass, CarrierEcho, CarrierLearningContext, CarrierRequest, TokenHash,
+    WebProcessRuntime,
+};
+use crate::config::WebCarrier;
+use crate::web::session::WebSession;
+use crate::web::trace::{TraceIdentity, TraceLifecycleEvent};
+
+impl WebProcessRuntime {
+    /// Returns authenticated current chain metadata after a committed retry conflict.
+    pub(crate) fn carrier_echo(
+        &self,
+        bootstrap_hash: TokenHash,
+        host: &str,
+        client_ip: IpAddr,
+        request: CarrierRequest,
+    ) -> Option<CarrierEcho> {
+        let state = self.state.lock();
+        let entry = state.bootstraps.get(&bootstrap_hash)?;
+        let session = entry.session.as_ref()?;
+        if !entry.used
+            || entry.profile.host != host
+            || entry.session_client_ip != Some(client_ip)
+            || entry
+                .carrier_request
+                .is_none_or(|current| !current.matches_client(request))
+            || !(matches!(
+                entry.carrier_phase,
+                CarrierChainPhase::CommittedPendingHealth | CarrierChainPhase::Healthy
+            ) || session.is_carrier_committed())
+        {
+            return None;
+        }
+        Some(CarrierEcho {
+            carrier: session.carrier(),
+            attempt: entry.carrier_attempt,
+            candidate_count: u8::try_from(entry.carrier_candidates.len()).unwrap_or(4),
+            deadline_secs: entry.profile.carrier_negotiation_deadlines_secs[3],
+            state: if entry.carrier_phase == CarrierChainPhase::Provisional
+                && session.is_carrier_committed()
+            {
+                CarrierChainPhase::CommittedPendingHealth.as_str()
+            } else {
+                entry.carrier_phase.as_str()
+            },
+        })
+    }
+
+    /// Restores the exact old attempt after successor admission fails.
+    pub(super) fn cancel_replacement(
+        &self,
+        bootstrap_hash: TokenHash,
+        old_session: &Arc<WebSession>,
+    ) {
+        old_session.cancel_carrier_supersede();
+        let mut state = self.state.lock();
+        if let Some(entry) = state.bootstraps.get_mut(&bootstrap_hash)
+            && entry
+                .session
+                .as_ref()
+                .is_some_and(|session| Arc::ptr_eq(session, old_session))
+        {
+            entry.carrier_transitioning = false;
+        }
+    }
+
+    /// Freezes replacement immediately after accepted carrier state mutation.
+    #[allow(clippy::too_many_arguments)]
+    pub(crate) fn carrier_committed(
+        self: &Arc<Self>,
+        bootstrap_hash: TokenHash,
+        session_hash: TokenHash,
+        attempt: u8,
+        carrier: WebCarrier,
+        class: CarrierClientClass,
+        client_ip: IpAddr,
+        identity: TraceIdentity,
+    ) -> bool {
+        let mut state = self.state.lock();
+        let scores = state.bootstraps.get_mut(&bootstrap_hash).and_then(|entry| {
+            if entry.carrier_attempt == attempt
+                && entry
+                    .session
+                    .as_ref()
+                    .is_some_and(|session| session.token_hash() == session_hash)
+                && entry.carrier_phase == CarrierChainPhase::Provisional
+            {
+                entry.carrier_phase = CarrierChainPhase::CommittedPendingHealth;
+                Some(entry.carrier_scores)
+            } else {
+                None
+            }
+        });
+        drop(state);
+        let Some(scores) = scores else { return false };
+        self.trace.record_carrier_lifecycle(
+            client_ip,
+            identity.clone(),
+            TraceLifecycleEvent::CarrierCommitted,
+            class.as_str(),
+            carrier,
+            attempt,
+            scores,
+            None,
+        );
+        true
+    }
+
+    /// Promotes one exact committed attempt after transport-specific health evidence.
+    #[allow(clippy::too_many_arguments)]
+    pub(crate) fn carrier_became_healthy(
+        &self,
+        bootstrap_hash: TokenHash,
+        session_hash: TokenHash,
+        attempt: u8,
+        carrier: WebCarrier,
+        class: CarrierClientClass,
+        learning_context: Option<CarrierLearningContext>,
+        client_ip: IpAddr,
+        identity: TraceIdentity,
+    ) {
+        let (scores, failures) = {
+            let mut state = self.state.lock();
+            let Some(entry) = state.bootstraps.get_mut(&bootstrap_hash) else {
+                return;
+            };
+            if entry.carrier_attempt != attempt
+                || entry.carrier_phase != CarrierChainPhase::CommittedPendingHealth
+                || entry
+                    .session
+                    .as_ref()
+                    .is_none_or(|session| session.token_hash() != session_hash)
+            {
+                return;
+            }
+            entry.carrier_phase = CarrierChainPhase::Healthy;
+            (entry.carrier_scores, entry.carrier_failures)
+        };
+        if let Some(context) = learning_context {
+            let now = Instant::now();
+            let mut learning = self.learning.lock();
+            let failures = failures.into_iter().flatten().collect::<Vec<_>>();
+            learning.record_chain(now, context.epoch, context, &failures, carrier);
+        }
+        self.trace.record_carrier_lifecycle(
+            client_ip,
+            identity,
+            TraceLifecycleEvent::CarrierHealthy,
+            class.as_str(),
+            carrier,
+            attempt,
+            scores,
+            None,
+        );
+    }
+}

src/web/manager/credentials.rs

@@ -3,19 +3,14 @@ use std::sync::Arc;
 use std::sync::atomic::Ordering;
 use std::time::{Duration, Instant};
 
-use sha2::{Digest, Sha256};
-use subtle::ConstantTimeEq;
 use zeroize::Zeroizing;
 
 use super::state::{
-    Bootstrap, allow_rate, decrement_map, evict_oldest_unused_bootstrap, matching_profile,
-    new_unique_token, profile_key, remove_expired_locked,
-};
-use super::{
-    BootstrapResult, CreateResult, ManagerError, TOKEN_BYTES, TokenHash, WebProcessRuntime,
+    Bootstrap, CarrierChainPhase, allow_rate, evict_oldest_unused_bootstrap, matching_profile,
+    new_unique_token, remove_expired_locked,
 };
+use super::{BootstrapResult, ManagerError, TOKEN_BYTES, TokenHash, WebProcessRuntime};
 use crate::config::WebRuntimeProfile;
-use crate::web::frame;
 use crate::web::session::WebSession;
 
 impl WebProcessRuntime {
@@ -78,6 +73,19 @@ impl WebProcessRuntime {
                 body_digest: [0; TOKEN_BYTES],
                 session_token: Zeroizing::new(String::new()),
                 session: None,
+                carrier_request: None,
+                carrier_candidates: Arc::from([]),
+                carrier_scores: [0; 4],
+                carrier_attempt: 0,
+                carrier_transitioning: false,
+                carrier_phase: CarrierChainPhase::Provisional,
+                carrier_started_at: None,
+                carrier_deadline_at: None,
+                carrier_failures: [None; 3],
+                carrier_learning_epoch: 0,
+                close_requested: false,
+                session_client_ip: None,
+                session_ip_learning_eligible: false,
                 used: false,
             },
         );
@@ -117,128 +125,6 @@ impl WebProcessRuntime {
             .map(|entry| (entry.trace_session_id, Arc::clone(&entry.profile)))
     }
 
-    /// Creates a session exactly once or replays the original successful result.
-    pub(crate) fn create_session(
-        self: &Arc<Self>,
-        bootstrap_hash: TokenHash,
-        host: &str,
-        client_ip: IpAddr,
-        body: &[u8],
-    ) -> std::result::Result<CreateResult, ManagerError> {
-        if !frame::validate_hello(body, &self.limits) {
-            return Err(ManagerError::Protocol);
-        }
-        let body_digest: TokenHash = Sha256::digest(body).into();
-        let generation = self.active_generation();
-        let config = generation.config();
-        let now = Instant::now();
-        let mut state = self.state.lock();
-        remove_expired_locked(&mut state, now);
-        let Some(entry) = state.bootstraps.get(&bootstrap_hash) else {
-            return Err(ManagerError::Authentication);
-        };
-        if entry.profile.host != host || now > entry.expires_at {
-            return Err(ManagerError::Authentication);
-        }
-        if entry.used {
-            let digest_matches = bool::from(entry.body_digest.ct_eq(&body_digest));
-            if !digest_matches {
-                return Err(ManagerError::Authentication);
-            }
-            let session = entry.session.as_ref().ok_or(ManagerError::Authentication)?;
-            let result = CreateResult {
-                token: entry.session_token.as_str().to_owned(),
-                carrier: session.carrier(),
-            };
-            let identity = session.trace_identity();
-            drop(state);
-            self.trace.record_lifecycle(
-                None,
-                Some(client_ip),
-                identity,
-                crate::web::trace::TraceLifecycleEvent::SessionReplayed,
-                None,
-                None,
-            );
-            return Ok(result);
-        }
-        let trace_session_id = entry.trace_session_id;
-        let issued_profile = Arc::clone(&entry.profile);
-        if state.closed || !config.web.enabled {
-            return Err(ManagerError::Closed);
-        }
-        let profile = config
-            .web
-            .runtime
-            .as_ref()
-            .and_then(|runtime| matching_profile(runtime, &issued_profile))
-            .filter(|profile| generation.proxy_shared.is_user_enabled(&profile.user))
-            .ok_or(ManagerError::Authentication)?;
-        let profile_key = profile_key(&profile);
-        if state.sessions.len() >= self.limits.max_sessions_global
-            || state.sessions_per_ip.get(&client_ip).copied().unwrap_or(0)
-                >= self.limits.max_sessions_per_ip
-            || state
-                .sessions_per_profile
-                .get(&profile_key)
-                .copied()
-                .unwrap_or(0)
-                >= profile.max_sessions
-            || !allow_rate(
-                &mut state.session_rate,
-                now,
-                self.limits.new_sessions_per_minute,
-                self.limits.new_sessions_burst,
-            )
-        {
-            self.limit_hits.fetch_add(1, Ordering::Relaxed);
-            return Err(ManagerError::Limit);
-        }
-        let Some((session_token, session_hash)) = new_unique_token(&generation, &state) else {
-            self.limit_hits.fetch_add(1, Ordering::Relaxed);
-            return Err(ManagerError::Limit);
-        };
-        let session = WebSession::new(
-            Arc::downgrade(self),
-            session_hash,
-            client_ip,
-            trace_session_id,
-            profile,
-            profile_key,
-            self.limits.clone(),
-            config.web.timeouts.clone(),
-        );
-        state.sessions.insert(session_hash, Arc::clone(&session));
-        *state.sessions_per_ip.entry(client_ip).or_insert(0) += 1;
-        *state.sessions_per_profile.entry(profile_key).or_insert(0) += 1;
-        let entry = state
-            .bootstraps
-            .get_mut(&bootstrap_hash)
-            .ok_or(ManagerError::Authentication)?;
-        entry.used = true;
-        entry.body_digest = body_digest;
-        entry.session_token = Zeroizing::new(session_token.clone());
-        entry.session = Some(Arc::clone(&session));
-        let issuance_ip = entry.issuance_ip;
-        decrement_map(&mut state.bootstraps_per_ip, &issuance_ip);
-        self.sessions_created.fetch_add(1, Ordering::Relaxed);
-        let identity = session.trace_identity();
-        let result = CreateResult {
-            token: session_token,
-            carrier: session.carrier(),
-        };
-        drop(state);
-        self.trace.record_lifecycle(
-            None,
-            Some(client_ip),
-            identity,
-            crate::web::trace::TraceLifecycleEvent::SessionCreated,
-            None,
-            None,
-        );
-        Ok(result)
-    }
-
     /// Resolves an authenticated session token.
     pub(crate) fn get_session(
         &self,
@@ -260,12 +146,24 @@ impl WebProcessRuntime {
         hash: TokenHash,
         host: &str,
     ) -> std::result::Result<(), ManagerError> {
-        let state = self.state.lock();
+        let mut state = self.state.lock();
         let session = state
             .sessions
             .get(&hash)
             .filter(|session| session.matches_host(host))
             .cloned();
+        if session.is_some() {
+            for bootstrap in state.bootstraps.values_mut() {
+                if bootstrap
+                    .session
+                    .as_ref()
+                    .is_some_and(|current| current.token_hash() == hash)
+                {
+                    bootstrap.close_requested = true;
+                    break;
+                }
+            }
+        }
         let closed = state
             .closed_tokens
             .get(&hash)

src/web/manager/learning.rs

@@ -0,0 +1,346 @@
+/// Telemt Carrier Selection and Failure Dampening - Copyright 2077 
+/// anhand des Kundenverhaltens Rückschlüsse gegen DSGVO ziehen...?!
+use std::collections::HashMap;
+use std::net::IpAddr;
+use std::time::{Duration, Instant};
+
+use sha2::{Digest, Sha256};
+
+use super::negotiation::{CarrierClientClass, CarrierLearningContext};
+use super::ProfileKey;
+use crate::config::WebCarrier;
+
+const PROFILE_WEIGHT: i16 = 4;
+const USER_AGENT_WEIGHT: i16 = 4;
+const IP_WEIGHT: i16 = 1;
+const SCORE_MIN: i8 = -8;
+const SCORE_MAX: i8 = 8;
+const PROFILE_MIN_OUTCOMES: u8 = 8;
+const PROFILE_MIN_COHORTS: usize = 4;
+const COHORT_CONTEXT: &[u8] = b"telemt-web-carrier-cohort-v1\0";
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+enum EvidenceKey {
+    Profile(ProfileKey),
+    UserAgent(ProfileKey, CarrierClientClass, [u8; 32]),
+    Ip(ProfileKey, IpAddr),
+}
+
+struct Evidence {
+    created_at: Instant,
+    lifetime: Duration,
+    scores: [i8; 4],
+    outcomes: u8,
+    cohorts: [Option<[u8; 32]>; PROFILE_MIN_COHORTS],
+}
+
+impl Evidence {
+    fn new(created_at: Instant, lifetime: Duration) -> Self {
+        Self {
+            created_at,
+            lifetime,
+            scores: [0; 4],
+            outcomes: 0,
+            cohorts: [None; PROFILE_MIN_COHORTS],
+        }
+    }
+
+    fn update(&mut self, carrier: WebCarrier, delta: i8, cohort: Option<[u8; 32]>) {
+        let score = &mut self.scores[carrier.index()];
+        *score = score.saturating_add(delta).clamp(SCORE_MIN, SCORE_MAX);
+        self.outcomes = self.outcomes.saturating_add(1).min(PROFILE_MIN_OUTCOMES);
+        if let Some(cohort) = cohort
+            && !self.cohorts.contains(&Some(cohort))
+            && let Some(slot) = self.cohorts.iter_mut().find(|slot| slot.is_none())
+        {
+            *slot = Some(cohort);
+        }
+    }
+}
+
+/// Process-local bounded fixed-window carrier evidence store.
+pub(super) struct CarrierLearning {
+    entries: HashMap<EvidenceKey, Evidence>,
+    capacity: usize,
+}
+
+impl CarrierLearning {
+    /// Creates an empty store under the restart-owned capacity ceiling.
+    pub(super) fn new(capacity: usize) -> Self {
+        Self {
+            entries: HashMap::with_capacity(capacity),
+            capacity,
+        }
+    }
+
+    /// Ranks supported configured candidates using only unexpired evidence.
+    pub(super) fn rank(
+        &mut self,
+        now: Instant,
+        configured: &[WebCarrier],
+        request: super::CarrierRequest,
+        profile_key: ProfileKey,
+        client_ip: IpAddr,
+    ) -> (Vec<WebCarrier>, [i16; 4]) {
+        self.prune(now);
+        let mut scores = [0i16; 4];
+        let profile = self.entries.get(&EvidenceKey::Profile(profile_key));
+        let profile_ready = profile.is_some_and(|entry| {
+            entry.outcomes >= PROFILE_MIN_OUTCOMES
+                && entry.cohorts.iter().flatten().count() >= PROFILE_MIN_COHORTS
+        });
+        let user_agent = self.entries.get(&EvidenceKey::UserAgent(
+            profile_key,
+            request.class(),
+            request.user_agent_hash(),
+        ));
+        let ip = self.entries.get(&EvidenceKey::Ip(profile_key, client_ip));
+        for carrier in WebCarrier::ALL {
+            let index = carrier.index();
+            if profile_ready {
+                scores[index] += i16::from(profile.map_or(0, |entry| entry.scores[index]))
+                    * PROFILE_WEIGHT;
+            }
+            scores[index] += i16::from(user_agent.map_or(0, |entry| entry.scores[index]))
+                * USER_AGENT_WEIGHT;
+            scores[index] +=
+                i16::from(ip.map_or(0, |entry| entry.scores[index])) * IP_WEIGHT;
+        }
+        let mut ranked = configured
+            .iter()
+            .copied()
+            .filter(|carrier| request.supports(*carrier))
+            .collect::<Vec<_>>();
+        ranked.sort_by_key(|carrier| std::cmp::Reverse(scores[carrier.index()]));
+        (ranked, scores)
+    }
+
+    /// Records one committed success or one server-accepted supersession failure.
+    pub(super) fn record(
+        &mut self,
+        now: Instant,
+        lifetime: Duration,
+        context: CarrierLearningContext,
+        carrier: WebCarrier,
+        success: bool,
+    ) {
+        self.prune(now);
+        let delta = if success { 1 } else { -1 };
+        let cohort = cohort_hash(context);
+        self.update(
+            EvidenceKey::Profile(context.profile_key),
+            now,
+            lifetime,
+            carrier,
+            delta,
+            Some(cohort),
+        );
+        self.update(
+            EvidenceKey::UserAgent(
+                context.profile_key,
+                context.class,
+                context.user_agent_hash,
+            ),
+            now,
+            lifetime,
+            carrier,
+            delta,
+            None,
+        );
+        self.update(
+            EvidenceKey::Ip(context.profile_key, context.client_ip),
+            now,
+            lifetime,
+            carrier,
+            delta,
+            None,
+        );
+    }
+
+    /// Removes fixed-window entries after their creation-time expiry.
+    pub(super) fn prune(&mut self, now: Instant) {
+        self.entries.retain(|_, entry| {
+            now.saturating_duration_since(entry.created_at) <= entry.lifetime
+        });
+    }
+
+    fn update(
+        &mut self,
+        key: EvidenceKey,
+        now: Instant,
+        lifetime: Duration,
+        carrier: WebCarrier,
+        delta: i8,
+        cohort: Option<[u8; 32]>,
+    ) {
+        if !self.entries.contains_key(&key) && self.entries.len() >= self.capacity {
+            let oldest = self
+                .entries
+                .iter()
+                .min_by_key(|(_, entry)| entry.created_at)
+                .map(|(key, _)| *key);
+            if let Some(oldest) = oldest {
+                self.entries.remove(&oldest);
+            }
+        }
+        self.entries
+            .entry(key)
+            .or_insert_with(|| Evidence::new(now, lifetime))
+            .update(carrier, delta, cohort);
+    }
+}
+
+fn cohort_hash(context: CarrierLearningContext) -> [u8; 32] {
+    let mut digest = Sha256::new();
+    digest.update(COHORT_CONTEXT);
+    digest.update(context.profile_key);
+    digest.update([match context.class {
+        CarrierClientClass::Legacy => 0,
+        CarrierClientClass::Bridge => 1,
+        CarrierClientClass::BrowserHint => 2,
+    }]);
+    digest.update(context.user_agent_hash);
+    match context.client_ip {
+        IpAddr::V4(address) => {
+            digest.update([4]);
+            digest.update(address.octets());
+        }
+        IpAddr::V6(address) => {
+            digest.update([6]);
+            digest.update(address.octets());
+        }
+    }
+    digest.finalize().into()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::web::manager::{CarrierCapabilities, CarrierRequest};
+
+    fn request(hash: u8) -> CarrierRequest {
+        CarrierRequest::automatic(
+            CarrierClientClass::Bridge,
+            CarrierCapabilities::all(),
+            1,
+            None,
+            [hash; 32],
+        )
+    }
+
+    #[test]
+    fn evidence_is_bounded_and_expires_without_sliding() {
+        let start = Instant::now();
+        let mut learning = CarrierLearning::new(3);
+        let context = CarrierLearningContext {
+            profile_key: [1; 32],
+            client_ip: "192.0.2.1".parse().unwrap(),
+            class: CarrierClientClass::Bridge,
+            user_agent_hash: [2; 32],
+        };
+        learning.record(
+            start,
+            Duration::from_secs(10),
+            context,
+            WebCarrier::Websocket,
+            true,
+        );
+        assert_eq!(learning.entries.len(), 3);
+        learning.record(
+            start + Duration::from_secs(5),
+            Duration::from_secs(10),
+            context,
+            WebCarrier::Websocket,
+            true,
+        );
+        learning.prune(start + Duration::from_secs(11));
+        assert!(learning.entries.is_empty());
+    }
+
+    #[test]
+    fn user_agent_and_ip_evidence_rank_stably() {
+        let now = Instant::now();
+        let mut learning = CarrierLearning::new(16);
+        let context = CarrierLearningContext {
+            profile_key: [1; 32],
+            client_ip: "192.0.2.1".parse().unwrap(),
+            class: CarrierClientClass::Bridge,
+            user_agent_hash: [2; 32],
+        };
+        learning.record(
+            now,
+            Duration::from_secs(10),
+            context,
+            WebCarrier::Websocket,
+            true,
+        );
+        let (ranked, scores) = learning.rank(
+            now,
+            &[WebCarrier::Https, WebCarrier::Websocket],
+            request(2),
+            context.profile_key,
+            context.client_ip,
+        );
+        assert_eq!(ranked, [WebCarrier::Websocket, WebCarrier::Https]);
+        assert_eq!(scores[WebCarrier::Websocket.index()], 5);
+    }
+
+    #[test]
+    fn profile_evidence_requires_outcome_and_cohort_thresholds() {
+        let now = Instant::now();
+        let profile_key = [1; 32];
+        let configured = [WebCarrier::Https, WebCarrier::Websocket];
+        let unrelated_ip = "198.51.100.10".parse().unwrap();
+        let mut learning = CarrierLearning::new(64);
+        for cohort in 1..=3u8 {
+            let context = CarrierLearningContext {
+                profile_key,
+                client_ip: IpAddr::V4(std::net::Ipv4Addr::new(192, 0, 2, cohort)),
+                class: CarrierClientClass::Bridge,
+                user_agent_hash: [cohort; 32],
+            };
+            for _ in 0..2 {
+                learning.record(
+                    now,
+                    Duration::from_secs(10),
+                    context,
+                    WebCarrier::Websocket,
+                    true,
+                );
+            }
+        }
+        let (ranked, _) = learning.rank(
+            now,
+            &configured,
+            request(99),
+            profile_key,
+            unrelated_ip,
+        );
+        assert_eq!(ranked, configured);
+
+        let fourth = CarrierLearningContext {
+            profile_key,
+            client_ip: "192.0.2.4".parse().unwrap(),
+            class: CarrierClientClass::Bridge,
+            user_agent_hash: [4; 32],
+        };
+        for _ in 0..2 {
+            learning.record(
+                now,
+                Duration::from_secs(10),
+                fourth,
+                WebCarrier::Websocket,
+                true,
+            );
+        }
+        let (ranked, scores) = learning.rank(
+            now,
+            &configured,
+            request(99),
+            profile_key,
+            unrelated_ip,
+        );
+        assert_eq!(ranked, [WebCarrier::Websocket, WebCarrier::Https]);
+        assert_eq!(scores[WebCarrier::Websocket.index()], 32);
+    }
+}

src/web/manager/lifecycle.rs

@@ -4,7 +4,9 @@ use std::time::{Duration, Instant};
 
 use tracing::info;
 
-use super::state::{ClosedToken, decrement_map, remove_bootstrap_locked, remove_expired_locked};
+use super::state::{
+    decrement_map, remember_closed_token_locked, remove_bootstrap_locked, remove_expired_locked,
+};
 use super::{ProfileKey, TokenHash, WebProcessRuntime};
 
 impl WebProcessRuntime {
@@ -22,33 +24,20 @@ impl WebProcessRuntime {
         }
         decrement_map(&mut state.sessions_per_ip, &client_ip);
         decrement_map(&mut state.sessions_per_profile, &profile_key);
-        let expiry = Instant::now()
-            + Duration::from_secs(
+        remember_closed_token_locked(
+            &mut state,
+            hash,
+            profile_host,
+            Duration::from_secs(
                 self.active_runtime
                     .load()
                     .config()
                     .web
                     .timeouts
                     .bootstrap_lifetime_secs,
+            ),
+            self.limits.max_sessions_global.saturating_mul(16),
         );
-        state.closed_tokens.insert(
-            hash,
-            ClosedToken {
-                expires_at: expiry,
-                host: profile_host.to_string(),
-            },
-        );
-        while state.closed_tokens.len() > self.limits.max_sessions_global.saturating_mul(16) {
-            let Some(oldest) = state
-                .closed_tokens
-                .iter()
-                .min_by_key(|(_, closed)| closed.expires_at)
-                .map(|(hash, _)| *hash)
-            else {
-                break;
-            };
-            state.closed_tokens.remove(&oldest);
-        }
         let bootstrap_hashes = state
             .bootstraps
             .iter()
@@ -78,6 +67,7 @@ impl WebProcessRuntime {
             state.bootstraps_per_ip.clear();
             state.sessions.values().cloned().collect::<Vec<_>>()
         };
+        self.stream_admission.lock().closed = true;
         for session in &sessions {
             session.close();
         }
@@ -96,10 +86,8 @@ impl WebProcessRuntime {
         let _ = tokio::time::timeout(Duration::from_secs(timeout_secs), waits).await;
         self.tasks.close();
         let _ = tokio::time::timeout(Duration::from_secs(timeout_secs), self.tasks.wait()).await;
-        let (sessions_live, streams_live) = {
-            let state = self.state.lock();
-            (state.sessions.len(), state.streams_live)
-        };
+        let sessions_live = self.state.lock().sessions.len();
+        let streams_live = self.stream_admission.lock().streams_live;
         let budget = self.data_budget.snapshot();
         info!(
             target: "telemt::web",
@@ -124,13 +112,53 @@ impl WebProcessRuntime {
     pub(super) fn cleanup(&self) {
         self.cleanup_websockets();
         let now = Instant::now();
-        let sessions = {
+        let generation = self.active_generation();
+        let config = &generation.config().web;
+        let learning_enabled = config.carrier_negotiation_enabled() && config.carrier_learning;
+        let mut learning = self.learning.lock();
+        let _ = learning.apply_policy(
+            now,
+            learning_enabled,
+            config.carrier_negotiation_aggressiveness,
+            Duration::from_secs(config.timeouts.carrier_learning_secs),
+        );
+        learning.prune(now);
+        drop(learning);
+        let (sessions, expired_chains) = {
             let mut state = self.state.lock();
+            let expired = state
+                .bootstraps
+                .iter()
+                .filter_map(|(hash, bootstrap)| {
+                    (bootstrap.carrier_phase == super::state::CarrierChainPhase::Provisional
+                        && bootstrap
+                            .carrier_deadline_at
+                            .is_some_and(|deadline| now >= deadline)
+                        && bootstrap
+                            .session
+                            .as_ref()
+                            .is_some_and(|session| !session.is_carrier_committed()))
+                    .then_some((*hash, bootstrap.session.clone()))
+                })
+                .collect::<Vec<_>>();
+            let expired_chains = expired
+                .iter()
+                .filter_map(|(_, session)| session.clone())
+                .collect::<Vec<_>>();
+            for (hash, _) in expired {
+                remove_bootstrap_locked(&mut state, hash);
+            }
             remove_expired_locked(&mut state, now);
-            state.sessions.values().cloned().collect::<Vec<_>>()
+            (
+                state.sessions.values().cloned().collect::<Vec<_>>(),
+                expired_chains,
+            )
         };
-        for session in sessions.into_iter().filter(|session| session.is_idle(now)) {
+        for session in expired_chains {
             session.close();
         }
+        for session in sessions {
+            session.close_if_due(now);
+        }
     }
 }

src/web/manager/negotiation.rs

@@ -0,0 +1,259 @@
+use std::net::IpAddr;
+
+use crate::config::WebCarrier;
+
+/// Stable client classification used only for carrier negotiation and learning.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub(crate) enum CarrierClientClass {
+    /// A client that did not present server-bridge negotiation metadata.
+    Legacy,
+    /// The generated bridge presented the explicit capability marker.
+    Bridge,
+    /// Strict same-origin browser metadata survived while the marker did not.
+    BrowserHint,
+    /// A native iOS client classified for diagnostics and learning only.
+    Ios,
+}
+
+impl CarrierClientClass {
+    /// Returns the non-sensitive token exposed by WEB debug lifecycle records.
+    pub(crate) const fn as_str(self) -> &'static str {
+        match self {
+            Self::Legacy => "legacy",
+            Self::Bridge => "bridge",
+            Self::BrowserHint => "browser-hint",
+            Self::Ios => "ios",
+        }
+    }
+}
+
+/// Canonical carrier failure category reported by the generated bridge.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) enum CarrierFailure {
+    /// The cumulative attempt deadline elapsed.
+    Timeout,
+    /// The browser observed a network failure.
+    Network,
+    /// A WebSocket upgrade or post-upgrade acknowledgement failed.
+    Upgrade,
+    /// The carrier returned an unexpected HTTP result.
+    Http,
+    /// The carrier violated its response or framing contract.
+    Protocol,
+}
+
+impl CarrierFailure {
+    /// Parses one canonical bridge failure token.
+    pub(crate) const fn parse(value: &str) -> Option<Self> {
+        match value.as_bytes() {
+            b"timeout" => Some(Self::Timeout),
+            b"network" => Some(Self::Network),
+            b"upgrade" => Some(Self::Upgrade),
+            b"http" => Some(Self::Http),
+            b"protocol" => Some(Self::Protocol),
+            _ => None,
+        }
+    }
+
+    /// Returns the canonical non-sensitive failure token.
+    pub(crate) const fn as_str(self) -> &'static str {
+        match self {
+            Self::Timeout => "timeout",
+            Self::Network => "network",
+            Self::Upgrade => "upgrade",
+            Self::Http => "http",
+            Self::Protocol => "protocol",
+        }
+    }
+}
+
+/// Validated carrier capability set sent by a negotiation-capable client.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) struct CarrierCapabilities(u8);
+
+impl CarrierCapabilities {
+    /// Returns a set containing every carrier implemented by the generated bridge.
+    pub(crate) const fn all() -> Self {
+        Self(0b1111)
+    }
+
+    /// Builds a set from a validated bit representation.
+    pub(crate) const fn from_bits(bits: u8) -> Option<Self> {
+        if bits != 0 && bits & !0b1111 == 0 {
+            Some(Self(bits))
+        } else {
+            None
+        }
+    }
+
+    /// Returns whether the bridge can run one carrier.
+    pub(crate) const fn contains(self, carrier: WebCarrier) -> bool {
+        self.0 & (1 << carrier.index()) != 0
+    }
+}
+
+/// Immutable metadata attached to one session-creation attempt.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) struct CarrierRequest {
+    class: CarrierClientClass,
+    capabilities: Option<CarrierCapabilities>,
+    attempt: Option<u8>,
+    failure: Option<CarrierFailure>,
+    user_agent_hash: [u8; 32],
+}
+
+impl CarrierRequest {
+    /// Constructs legacy metadata without enabling negotiation or learning.
+    pub(crate) const fn legacy(user_agent_hash: [u8; 32]) -> Self {
+        Self {
+            class: CarrierClientClass::Legacy,
+            capabilities: None,
+            attempt: None,
+            failure: None,
+            user_agent_hash,
+        }
+    }
+
+    /// Constructs a metadata-free native client without inferring capabilities.
+    pub(crate) const fn ios(user_agent_hash: [u8; 32]) -> Self {
+        Self {
+            class: CarrierClientClass::Ios,
+            capabilities: None,
+            attempt: None,
+            failure: None,
+            user_agent_hash,
+        }
+    }
+
+    /// Constructs validated automatic-negotiation metadata.
+    pub(crate) const fn automatic(
+        class: CarrierClientClass,
+        capabilities: CarrierCapabilities,
+        attempt: u8,
+        failure: Option<CarrierFailure>,
+        user_agent_hash: [u8; 32],
+    ) -> Self {
+        Self {
+            class,
+            capabilities: Some(capabilities),
+            attempt: Some(attempt),
+            failure,
+            user_agent_hash,
+        }
+    }
+
+    /// Returns whether this request participates in server-side negotiation.
+    pub(crate) const fn is_automatic(self) -> bool {
+        self.capabilities.is_some()
+    }
+
+    /// Returns whether server capability filtering applies to this request.
+    pub(crate) const fn uses_capabilities(self) -> bool {
+        self.capabilities.is_some()
+    }
+
+    /// Returns the canonical attempt number when negotiation is active.
+    pub(crate) const fn attempt(self) -> Option<u8> {
+        self.attempt
+    }
+
+    /// Returns the reported reason for advancing from the previous candidate.
+    pub(crate) const fn failure(self) -> Option<CarrierFailure> {
+        self.failure
+    }
+
+    /// Returns whether a carrier is supported by this request.
+    pub(crate) const fn supports(self, carrier: WebCarrier) -> bool {
+        match self.capabilities {
+            Some(capabilities) => capabilities.contains(carrier),
+            None => false,
+        }
+    }
+
+    /// Returns the stable non-sensitive client class.
+    pub(crate) const fn class(self) -> CarrierClientClass {
+        self.class
+    }
+
+    /// Returns the normalized User-Agent digest.
+    pub(crate) const fn user_agent_hash(self) -> [u8; 32] {
+        self.user_agent_hash
+    }
+
+    /// Checks the capability identity frozen across sequential attempts.
+    pub(crate) fn matches_client(self, other: Self) -> bool {
+        self.class == other.class
+            && self.capabilities_bits() == other.capabilities_bits()
+            && self.user_agent_hash == other.user_agent_hash
+    }
+
+    /// Checks the complete idempotent identity of one exact attempt request.
+    pub(crate) fn matches_attempt(self, other: Self) -> bool {
+        self.matches_client(other) && self.attempt == other.attempt && self.failure == other.failure
+    }
+
+    fn capabilities_bits(self) -> Option<u8> {
+        self.capabilities.map(|capabilities| capabilities.0)
+    }
+}
+
+/// Returns the cumulative deadline slot assigned to one carrier attempt.
+pub(super) const fn carrier_attempt_deadline_index(
+    candidate_count: u8,
+    attempt: u8,
+) -> Option<usize> {
+    if candidate_count == 0 || candidate_count > 4 || attempt == 0 || attempt > candidate_count {
+        return None;
+    }
+    if attempt == candidate_count {
+        Some(3)
+    } else {
+        Some((attempt - 1) as usize)
+    }
+}
+
+/// Secret-independent evidence owner frozen into an automatic session.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) struct CarrierLearningContext {
+    /// Stable profile namespace.
+    pub(crate) profile_key: super::ProfileKey,
+    /// Effective client address from the trusted L7 boundary.
+    pub(crate) client_ip: IpAddr,
+    /// Client-class namespace for normalized User-Agent evidence.
+    pub(crate) class: CarrierClientClass,
+    /// Domain-separated normalized User-Agent digest.
+    pub(crate) user_agent_hash: [u8; 32],
+    /// Hot-reload epoch that rejects late outcomes from an older policy.
+    pub(crate) epoch: u64,
+    /// Whether the authoritative client address is safe to use as learning evidence.
+    pub(crate) ip_learning_eligible: bool,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::carrier_attempt_deadline_index;
+
+    #[test]
+    fn final_candidate_uses_the_final_cumulative_deadline_slot() {
+        assert_eq!(carrier_attempt_deadline_index(1, 1), Some(3));
+        assert_eq!(carrier_attempt_deadline_index(2, 1), Some(0));
+        assert_eq!(carrier_attempt_deadline_index(2, 2), Some(3));
+        assert_eq!(carrier_attempt_deadline_index(3, 1), Some(0));
+        assert_eq!(carrier_attempt_deadline_index(3, 2), Some(1));
+        assert_eq!(carrier_attempt_deadline_index(3, 3), Some(3));
+        assert_eq!(carrier_attempt_deadline_index(4, 1), Some(0));
+        assert_eq!(carrier_attempt_deadline_index(4, 2), Some(1));
+        assert_eq!(carrier_attempt_deadline_index(4, 3), Some(2));
+        assert_eq!(carrier_attempt_deadline_index(4, 4), Some(3));
+    }
+
+    #[test]
+    fn invalid_candidate_or_attempt_counts_have_no_deadline_slot() {
+        for (candidate_count, attempt) in [(0, 1), (5, 1), (1, 0), (1, 2), (3, 4)] {
+            assert_eq!(
+                carrier_attempt_deadline_index(candidate_count, attempt),
+                None
+            );
+        }
+    }
+}

src/web/manager/session_admission.rs

@@ -0,0 +1,37 @@
+use std::net::IpAddr;
+use std::sync::atomic::Ordering;
+use std::time::Instant;
+
+use super::state::{ManagerState, allow_rate};
+use super::{ProfileKey, WebProcessRuntime};
+use crate::config::WebRuntimeProfile;
+
+/// Applies process, address, profile, and rate ceilings to one initial session.
+pub(super) fn admit_initial(
+    runtime: &WebProcessRuntime,
+    state: &mut ManagerState,
+    now: Instant,
+    client_ip: IpAddr,
+    profile_key: ProfileKey,
+    profile: &WebRuntimeProfile,
+) -> bool {
+    let admitted = state.sessions.len() < runtime.limits.max_sessions_global
+        && state.sessions_per_ip.get(&client_ip).copied().unwrap_or(0)
+            < runtime.limits.max_sessions_per_ip
+        && state
+            .sessions_per_profile
+            .get(&profile_key)
+            .copied()
+            .unwrap_or(0)
+            < profile.max_sessions
+        && allow_rate(
+            &mut state.session_rate,
+            now,
+            runtime.limits.new_sessions_per_minute,
+            runtime.limits.new_sessions_burst,
+        );
+    if !admitted {
+        runtime.limit_hits.fetch_add(1, Ordering::Relaxed);
+    }
+    admitted
+}

src/web/manager/session_creation.rs

@@ -0,0 +1,553 @@
+use std::net::IpAddr;
+use std::sync::Arc;
+use std::sync::atomic::Ordering;
+use std::time::{Duration, Instant};
+
+use sha2::{Digest, Sha256};
+use subtle::ConstantTimeEq;
+use zeroize::Zeroizing;
+
+use super::negotiation::carrier_attempt_deadline_index;
+use super::session_admission::admit_initial;
+use super::state::{
+    CarrierChainPhase, decrement_map, matching_profile, new_unique_token, profile_key,
+    remember_closed_token_locked, remove_expired_locked,
+};
+use super::{
+    CarrierLearningContext, CarrierRequest, CreateResult, ManagerError, TokenHash,
+    WebProcessRuntime,
+};
+use crate::config::{WebCarrier, WebRuntimeProfile};
+use crate::web::frame;
+use crate::web::session::WebSession;
+use crate::web::trace::TraceLifecycleEvent;
+
+struct Replacement {
+    old_session: Arc<WebSession>,
+    profile: Arc<WebRuntimeProfile>,
+    profile_key: super::ProfileKey,
+    trace_session_id: u64,
+    attempt: u8,
+    carrier: WebCarrier,
+    request: CarrierRequest,
+    scores: [i16; 4],
+    learning_epoch: u64,
+    ip_learning_eligible: bool,
+    carrier_deadline_at: Instant,
+}
+
+impl WebProcessRuntime {
+    /// Creates, replays, or atomically supersedes one pre-commit carrier session.
+    pub(crate) fn create_session(
+        self: &Arc<Self>,
+        bootstrap_hash: TokenHash,
+        host: &str,
+        client_ip: IpAddr,
+        body: &[u8],
+        carrier_request: CarrierRequest,
+        ip_learning_eligible: bool,
+    ) -> std::result::Result<CreateResult, ManagerError> {
+        if !frame::validate_hello(body, &self.limits) {
+            return Err(ManagerError::Protocol);
+        }
+        let body_digest: TokenHash = Sha256::digest(body).into();
+        let generation = self.active_generation();
+        let config = generation.config();
+        let now = Instant::now();
+        let mut state = self.state.lock();
+        remove_expired_locked(&mut state, now);
+        let Some(entry) = state.bootstraps.get(&bootstrap_hash) else {
+            return Err(ManagerError::Authentication);
+        };
+        if entry.profile.host != host || now > entry.expires_at {
+            return Err(ManagerError::Authentication);
+        }
+        if entry.used {
+            if entry
+                .carrier_deadline_at
+                .is_some_and(|deadline| now >= deadline)
+                && entry
+                    .session
+                    .as_ref()
+                    .is_some_and(|session| !session.is_carrier_committed())
+            {
+                let session = entry.session.clone();
+                drop(state);
+                if let Some(session) = session {
+                    session.close();
+                }
+                return Err(ManagerError::Closed);
+            }
+            if entry.close_requested {
+                return Err(ManagerError::Closed);
+            }
+            let digest_matches = bool::from(entry.body_digest.ct_eq(&body_digest));
+            let client_matches = entry.session_client_ip == Some(client_ip)
+                && entry.session_ip_learning_eligible == ip_learning_eligible;
+            let request_matches = entry
+                .carrier_request
+                .is_some_and(|current| current.matches_client(carrier_request));
+            if !digest_matches || !client_matches || !request_matches {
+                return Err(ManagerError::Authentication);
+            }
+            if entry.carrier_transitioning {
+                return Err(ManagerError::Concurrent);
+            }
+            if carrier_request.attempt() == Some(entry.carrier_attempt)
+                || (!carrier_request.is_automatic() && entry.carrier_attempt == 1)
+            {
+                if entry
+                    .carrier_request
+                    .is_none_or(|current| !current.matches_attempt(carrier_request))
+                {
+                    return Err(ManagerError::Authentication);
+                }
+                let session = entry.session.as_ref().ok_or(ManagerError::Authentication)?;
+                let automatic = carrier_request.is_automatic();
+                let carrier_state = if entry.carrier_phase == CarrierChainPhase::Provisional
+                    && session.is_carrier_committed()
+                {
+                    CarrierChainPhase::CommittedPendingHealth.as_str()
+                } else {
+                    entry.carrier_phase.as_str()
+                };
+                let result = CreateResult {
+                    token: entry.session_token.as_str().to_owned(),
+                    carrier: session.carrier(),
+                    attempt: carrier_request.attempt(),
+                    candidate_count: automatic
+                        .then(|| u8::try_from(entry.carrier_candidates.len()).unwrap_or(4)),
+                    deadline_secs: automatic
+                        .then_some(entry.profile.carrier_negotiation_deadlines_secs[3]),
+                    carrier_state: automatic.then_some(carrier_state),
+                };
+                let identity = session.trace_identity();
+                drop(state);
+                self.trace.record_lifecycle(
+                    None,
+                    Some(client_ip),
+                    identity,
+                    TraceLifecycleEvent::SessionReplayed,
+                    None,
+                    None,
+                );
+                return Ok(result);
+            }
+            let next_attempt = entry.carrier_attempt.saturating_add(1);
+            if !carrier_request.is_automatic()
+                || carrier_request.attempt() != Some(next_attempt)
+                || matches!(
+                    entry.carrier_phase,
+                    CarrierChainPhase::CommittedPendingHealth | CarrierChainPhase::Healthy
+                )
+            {
+                return Err(
+                    if matches!(
+                        entry.carrier_phase,
+                        CarrierChainPhase::CommittedPendingHealth | CarrierChainPhase::Healthy
+                    ) {
+                        ManagerError::Committed
+                    } else {
+                        ManagerError::Protocol
+                    },
+                );
+            }
+            let Some(carrier) = entry
+                .carrier_candidates
+                .get(usize::from(next_attempt - 1))
+                .copied()
+            else {
+                return Err(ManagerError::Protocol);
+            };
+            let candidate_count =
+                u8::try_from(entry.carrier_candidates.len()).map_err(|_| ManagerError::Protocol)?;
+            let deadline_index = carrier_attempt_deadline_index(candidate_count, next_attempt)
+                .ok_or(ManagerError::Protocol)?;
+            if entry.carrier_started_at.is_some_and(|started| {
+                now.saturating_duration_since(started)
+                    >= Duration::from_secs(
+                        entry.profile.carrier_negotiation_deadlines_secs[deadline_index],
+                    )
+            }) {
+                return Err(ManagerError::Protocol);
+            }
+            let old_session = entry.session.clone().ok_or(ManagerError::Authentication)?;
+            let replacement = Replacement {
+                profile: Arc::clone(&entry.profile),
+                profile_key: old_session.profile_key(),
+                trace_session_id: entry.trace_session_id,
+                old_session,
+                attempt: next_attempt,
+                carrier,
+                request: carrier_request,
+                scores: entry.carrier_scores,
+                learning_epoch: entry.carrier_learning_epoch,
+                ip_learning_eligible,
+                carrier_deadline_at: entry.carrier_deadline_at.ok_or(ManagerError::Protocol)?,
+            };
+            state
+                .bootstraps
+                .get_mut(&bootstrap_hash)
+                .ok_or(ManagerError::Authentication)?
+                .carrier_transitioning = true;
+            drop(state);
+            return self.replace_session(bootstrap_hash, client_ip, replacement);
+        }
+
+        if (carrier_request.is_automatic() && carrier_request.attempt() != Some(1))
+            || (!carrier_request.is_automatic() && carrier_request.attempt().is_some())
+        {
+            return Err(ManagerError::Protocol);
+        }
+        let trace_session_id = entry.trace_session_id;
+        let issued_profile = Arc::clone(&entry.profile);
+        if state.closed || !config.web.enabled {
+            return Err(ManagerError::Closed);
+        }
+        let profile = config
+            .web
+            .runtime
+            .as_ref()
+            .and_then(|runtime| matching_profile(runtime, &issued_profile))
+            .filter(|profile| generation.proxy_shared.is_user_enabled(&profile.user))
+            .ok_or(ManagerError::Authentication)?;
+        let profile_key = profile_key(&profile);
+        if carrier_request.is_automatic() && !profile.carrier_negotiation_enabled {
+            return Err(ManagerError::Protocol);
+        }
+        let capability_selection =
+            carrier_request.uses_capabilities() && profile.carrier_negotiation_enabled;
+        let learning_policy = (
+            config.web.carrier_negotiation_enabled() && config.web.carrier_learning,
+            config.web.carrier_negotiation_aggressiveness,
+            Duration::from_secs(config.web.timeouts.carrier_learning_secs),
+        );
+        let (candidates, scores, learning_epoch) = if capability_selection
+            && profile.carrier_learning
+        {
+            let learning = self.learning.lock();
+            if let Some(epoch) =
+                learning.epoch_for_policy(learning_policy.0, learning_policy.1, learning_policy.2)
+            {
+                let (candidates, scores) = learning.rank(
+                    now,
+                    &profile.carriers,
+                    carrier_request,
+                    profile_key,
+                    client_ip,
+                    ip_learning_eligible,
+                );
+                (candidates, scores, Some(epoch))
+            } else {
+                (
+                    profile
+                        .carriers
+                        .iter()
+                        .copied()
+                        .filter(|carrier| carrier_request.supports(*carrier))
+                        .collect(),
+                    [0; 4],
+                    None,
+                )
+            }
+        } else if capability_selection {
+            (
+                profile
+                    .carriers
+                    .iter()
+                    .copied()
+                    .filter(|carrier| carrier_request.supports(*carrier))
+                    .collect(),
+                [0; 4],
+                None,
+            )
+        } else if carrier_request.uses_capabilities() && !carrier_request.supports(profile.carrier)
+        {
+            return Err(ManagerError::Protocol);
+        } else {
+            (vec![profile.carrier], [0; 4], None)
+        };
+        let Some(carrier) = candidates.first().copied() else {
+            return Err(ManagerError::Protocol);
+        };
+        if !admit_initial(self, &mut state, now, client_ip, profile_key, &profile) {
+            return Err(ManagerError::Limit);
+        }
+        let Some((session_token, session_hash)) = new_unique_token(&generation, &state) else {
+            self.limit_hits.fetch_add(1, Ordering::Relaxed);
+            return Err(ManagerError::Limit);
+        };
+        let carrier_deadline_at = carrier_request
+            .is_automatic()
+            .then_some(now + Duration::from_secs(profile.carrier_negotiation_deadlines_secs[3]));
+        let learning_context = learning_epoch.map(|epoch| CarrierLearningContext {
+            profile_key,
+            client_ip,
+            class: carrier_request.class(),
+            user_agent_hash: carrier_request.user_agent_hash(),
+            epoch,
+            ip_learning_eligible,
+        });
+        let session = WebSession::new(
+            Arc::downgrade(self),
+            session_hash,
+            client_ip,
+            trace_session_id,
+            Arc::clone(&profile),
+            profile_key,
+            carrier,
+            1,
+            bootstrap_hash,
+            carrier_deadline_at,
+            carrier_request.class(),
+            learning_context,
+            carrier_request.is_automatic(),
+            self.limits.clone(),
+            config.web.timeouts.clone(),
+        );
+        state.sessions.insert(session_hash, Arc::clone(&session));
+        *state.sessions_per_ip.entry(client_ip).or_insert(0) += 1;
+        *state.sessions_per_profile.entry(profile_key).or_insert(0) += 1;
+        let entry = state
+            .bootstraps
+            .get_mut(&bootstrap_hash)
+            .ok_or(ManagerError::Authentication)?;
+        entry.used = true;
+        entry.body_digest = body_digest;
+        entry.session_token = Zeroizing::new(session_token.clone());
+        entry.session = Some(Arc::clone(&session));
+        entry.carrier_request = Some(carrier_request);
+        entry.carrier_candidates = candidates.into();
+        entry.carrier_scores = scores;
+        entry.carrier_attempt = 1;
+        entry.carrier_phase = CarrierChainPhase::Provisional;
+        entry.carrier_started_at = carrier_request.is_automatic().then_some(now);
+        entry.carrier_deadline_at = carrier_deadline_at;
+        entry.carrier_failures = [None; 3];
+        entry.carrier_learning_epoch = learning_epoch.unwrap_or(0);
+        entry.expires_at = now + Duration::from_secs(config.web.timeouts.bootstrap_lifetime_secs);
+        entry.session_client_ip = Some(client_ip);
+        entry.session_ip_learning_eligible = ip_learning_eligible;
+        let issuance_ip = entry.issuance_ip;
+        let candidate_count = u8::try_from(entry.carrier_candidates.len()).unwrap_or(4);
+        decrement_map(&mut state.bootstraps_per_ip, &issuance_ip);
+        self.sessions_created.fetch_add(1, Ordering::Relaxed);
+        let identity = session.trace_identity();
+        let result = CreateResult {
+            token: session_token,
+            carrier,
+            attempt: carrier_request.attempt(),
+            candidate_count: carrier_request.is_automatic().then_some(candidate_count),
+            deadline_secs: carrier_request
+                .is_automatic()
+                .then_some(profile.carrier_negotiation_deadlines_secs[3]),
+            carrier_state: carrier_request
+                .is_automatic()
+                .then_some(CarrierChainPhase::Provisional.as_str()),
+        };
+        drop(state);
+        self.trace.record_carrier_lifecycle(
+            client_ip,
+            identity.clone(),
+            TraceLifecycleEvent::CarrierClassified,
+            carrier_request.class().as_str(),
+            carrier,
+            1,
+            scores,
+            None,
+        );
+        self.trace.record_carrier_lifecycle(
+            client_ip,
+            identity.clone(),
+            TraceLifecycleEvent::CarrierSelected,
+            carrier_request.class().as_str(),
+            carrier,
+            1,
+            scores,
+            None,
+        );
+        self.trace.record_lifecycle(
+            None,
+            Some(client_ip),
+            identity,
+            TraceLifecycleEvent::SessionCreated,
+            None,
+            None,
+        );
+        Ok(result)
+    }
+
+    fn replace_session(
+        self: &Arc<Self>,
+        bootstrap_hash: TokenHash,
+        client_ip: IpAddr,
+        replacement: Replacement,
+    ) -> std::result::Result<CreateResult, ManagerError> {
+        if !replacement.old_session.begin_carrier_supersede() {
+            let committed = replacement.old_session.is_carrier_committed();
+            self.cancel_replacement(bootstrap_hash, &replacement.old_session);
+            return Err(if committed {
+                ManagerError::Committed
+            } else {
+                ManagerError::Closed
+            });
+        }
+        let generation = self.active_generation();
+        let config = generation.config();
+        let now = Instant::now();
+        let mut state = self.state.lock();
+        remove_expired_locked(&mut state, now);
+        let valid = state.bootstraps.get(&bootstrap_hash).is_some_and(|entry| {
+            entry.carrier_transitioning
+                && entry.carrier_phase == CarrierChainPhase::Provisional
+                && !entry.close_requested
+                && entry.carrier_attempt.saturating_add(1) == replacement.attempt
+                && now < replacement.carrier_deadline_at
+                && entry
+                    .session
+                    .as_ref()
+                    .is_some_and(|session| Arc::ptr_eq(session, &replacement.old_session))
+        }) && state
+            .sessions
+            .get(&replacement.old_session.token_hash())
+            .is_some_and(|session| Arc::ptr_eq(session, &replacement.old_session));
+        if !valid
+            || state.closed
+            || !config.web.enabled
+            || !generation
+                .proxy_shared
+                .is_user_enabled(&replacement.profile.user)
+        {
+            drop(state);
+            self.cancel_replacement(bootstrap_hash, &replacement.old_session);
+            return Err(ManagerError::Closed);
+        }
+        let Some((session_token, session_hash)) = new_unique_token(&generation, &state) else {
+            self.limit_hits.fetch_add(1, Ordering::Relaxed);
+            drop(state);
+            self.cancel_replacement(bootstrap_hash, &replacement.old_session);
+            return Err(ManagerError::Limit);
+        };
+        let learning_context = (replacement.profile.carrier_learning
+            && replacement.learning_epoch != 0)
+            .then_some(CarrierLearningContext {
+                profile_key: replacement.profile_key,
+                client_ip,
+                class: replacement.request.class(),
+                user_agent_hash: replacement.request.user_agent_hash(),
+                epoch: replacement.learning_epoch,
+                ip_learning_eligible: replacement.ip_learning_eligible,
+            });
+        let session = WebSession::new(
+            Arc::downgrade(self),
+            session_hash,
+            client_ip,
+            replacement.trace_session_id,
+            Arc::clone(&replacement.profile),
+            replacement.profile_key,
+            replacement.carrier,
+            replacement.attempt,
+            bootstrap_hash,
+            Some(replacement.carrier_deadline_at),
+            replacement.request.class(),
+            learning_context,
+            true,
+            self.limits.clone(),
+            replacement.old_session.timeouts().clone(),
+        );
+        let Some(supersede) = replacement.old_session.prepare_carrier_supersede() else {
+            drop(state);
+            self.cancel_replacement(bootstrap_hash, &replacement.old_session);
+            session.close();
+            return Err(ManagerError::Closed);
+        };
+        let old_hash = replacement.old_session.token_hash();
+        state.sessions.remove(&old_hash);
+        remember_closed_token_locked(
+            &mut state,
+            old_hash,
+            &replacement.profile.host,
+            Duration::from_secs(config.web.timeouts.bootstrap_lifetime_secs),
+            self.limits.max_sessions_global.saturating_mul(16),
+        );
+        state.sessions.insert(session_hash, Arc::clone(&session));
+        let entry = state
+            .bootstraps
+            .get_mut(&bootstrap_hash)
+            .ok_or(ManagerError::Authentication)?;
+        entry.session_token = Zeroizing::new(session_token.clone());
+        entry.session = Some(Arc::clone(&session));
+        entry.carrier_request = Some(replacement.request);
+        entry.carrier_attempt = replacement.attempt;
+        entry.carrier_transitioning = false;
+        entry.carrier_phase = CarrierChainPhase::Provisional;
+        if let Some(slot) = entry
+            .carrier_failures
+            .get_mut(usize::from(replacement.attempt.saturating_sub(2)))
+        {
+            *slot = Some(replacement.old_session.carrier());
+        }
+        self.sessions_created.fetch_add(1, Ordering::Relaxed);
+        self.sessions_closed.fetch_add(1, Ordering::Relaxed);
+        let result = CreateResult {
+            token: session_token,
+            carrier: replacement.carrier,
+            attempt: Some(replacement.attempt),
+            candidate_count: Some(u8::try_from(entry.carrier_candidates.len()).unwrap_or(4)),
+            deadline_secs: Some(entry.profile.carrier_negotiation_deadlines_secs[3]),
+            carrier_state: Some(CarrierChainPhase::Provisional.as_str()),
+        };
+        let identity = session.trace_identity();
+        let old_identity = replacement.old_session.trace_identity();
+        drop(state);
+        supersede.finish();
+        self.trace.record_carrier_lifecycle(
+            client_ip,
+            old_identity.clone(),
+            TraceLifecycleEvent::CarrierFailed,
+            replacement.request.class().as_str(),
+            replacement.old_session.carrier(),
+            replacement.attempt - 1,
+            replacement.scores,
+            replacement
+                .request
+                .failure()
+                .map(|failure| failure.as_str()),
+        );
+        self.trace.record_carrier_lifecycle(
+            client_ip,
+            old_identity,
+            TraceLifecycleEvent::CarrierSuperseded,
+            replacement.request.class().as_str(),
+            replacement.old_session.carrier(),
+            replacement.attempt - 1,
+            replacement.scores,
+            replacement
+                .request
+                .failure()
+                .map(|failure| failure.as_str()),
+        );
+        self.trace.record_carrier_lifecycle(
+            client_ip,
+            identity.clone(),
+            TraceLifecycleEvent::CarrierSelected,
+            replacement.request.class().as_str(),
+            replacement.carrier,
+            replacement.attempt,
+            replacement.scores,
+            None,
+        );
+        self.trace.record_lifecycle(
+            None,
+            Some(client_ip),
+            identity,
+            TraceLifecycleEvent::SessionCreated,
+            None,
+            replacement
+                .request
+                .failure()
+                .map(|failure| failure.as_str()),
+        );
+        Ok(result)
+    }
+}

src/web/manager/state.rs

@@ -1,19 +1,36 @@
 use std::collections::{HashMap, HashSet};
 use std::net::{IpAddr, SocketAddr};
 use std::sync::Arc;
-use std::time::Instant;
+use std::time::{Duration, Instant};
 
 use base64::Engine as _;
 use sha2::{Digest, Sha256};
 use zeroize::Zeroizing;
 
-use super::{ProfileKey, TOKEN_BYTES, TokenHash};
-use crate::config::{WebRuntimeConfig, WebRuntimeProfile};
+use super::{CarrierRequest, ProfileKey, TOKEN_BYTES, TokenHash};
+use crate::config::{WebCarrier, WebRuntimeConfig, WebRuntimeProfile};
 use crate::maestro::generation::RuntimeGeneration;
 use crate::web::session::WebSession;
 
 const WEB_PROFILE_OWNER_CONTEXT: &[u8] = b"telemt-web-profile-owner-v1\0";
 
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub(super) enum CarrierChainPhase {
+    Provisional,
+    CommittedPendingHealth,
+    Healthy,
+}
+
+impl CarrierChainPhase {
+    pub(super) const fn as_str(self) -> &'static str {
+        match self {
+            Self::Provisional => "provisional",
+            Self::CommittedPendingHealth => "committed",
+            Self::Healthy => "healthy",
+        }
+    }
+}
+
 /// One issued bootstrap and optional idempotent session-creation replay state.
 pub(super) struct Bootstrap {
     /// Credential and replay-state expiry deadline.
@@ -32,6 +49,32 @@ pub(super) struct Bootstrap {
     pub(super) session_token: Zeroizing<String>,
     /// Created session retained while retry replay remains valid.
     pub(super) session: Option<Arc<WebSession>>,
+    /// Metadata that defines exact attempt replay and candidate advancement.
+    pub(super) carrier_request: Option<CarrierRequest>,
+    /// Learning-ranked carrier order frozen by the first automatic attempt.
+    pub(super) carrier_candidates: Arc<[WebCarrier]>,
+    /// Weighted learning scores captured when the candidate order was frozen.
+    pub(super) carrier_scores: [i16; 4],
+    /// Current one-based carrier attempt, or zero before session creation.
+    pub(super) carrier_attempt: u8,
+    /// Prevents concurrent retries from replacing the same attempt twice.
+    pub(super) carrier_transitioning: bool,
+    /// Manager-owned attempt-chain phase used for replacement linearization.
+    pub(super) carrier_phase: CarrierChainPhase,
+    /// Monotonic start of the first automatic session attempt.
+    pub(super) carrier_started_at: Option<Instant>,
+    /// Absolute server-side end of the automatic attempt chain.
+    pub(super) carrier_deadline_at: Option<Instant>,
+    /// Failed candidates staged until one winner becomes healthy.
+    pub(super) carrier_failures: [Option<WebCarrier>; 3],
+    /// Learning-policy epoch frozen by the first automatic attempt.
+    pub(super) carrier_learning_epoch: u64,
+    /// DELETE observed before an in-flight replacement committed its swap.
+    pub(super) close_requested: bool,
+    /// Effective address frozen by the first session-creation request.
+    pub(super) session_client_ip: Option<IpAddr>,
+    /// Whether the first request carried an authoritative public forwarded address.
+    pub(super) session_ip_learning_eligible: bool,
     /// Distinguishes unused issuance quota from completed creation replay state.
     pub(super) used: bool,
 }
@@ -56,6 +99,20 @@ struct StreamPortState {
     next: u16,
 }
 
+/// Stream admission and KDF tuple ownership isolated from credential transitions.
+#[derive(Default)]
+pub(super) struct StreamAdmissionState {
+    /// Process shutdown admission latch.
+    pub(super) closed: bool,
+    /// Live stream counts by stable profile key.
+    pub(super) streams_per_profile: HashMap<ProfileKey, usize>,
+    /// Process-wide live relay-task count.
+    pub(super) streams_live: usize,
+    stream_ports: HashMap<(IpAddr, SocketAddr), StreamPortState>,
+    /// Logical-stream creation rate limiter.
+    pub(super) stream_rate: RateState,
+}
+
 /// Process-wide WEB registries and quota accounting protected by one short lock.
 #[derive(Default)]
 pub(super) struct ManagerState {
@@ -71,17 +128,10 @@ pub(super) struct ManagerState {
     pub(super) sessions_per_ip: HashMap<IpAddr, usize>,
     /// Live session counts by stable profile key.
     pub(super) sessions_per_profile: HashMap<ProfileKey, usize>,
-    /// Live relay-task counts by stable profile key.
-    pub(super) streams_per_profile: HashMap<ProfileKey, usize>,
-    /// Process-wide live relay-task count.
-    pub(super) streams_live: usize,
-    stream_ports: HashMap<(IpAddr, SocketAddr), StreamPortState>,
     /// Bootstrap issuance rate limiter.
     pub(super) bootstrap_rate: RateState,
     /// Session creation rate limiter.
     pub(super) session_rate: RateState,
-    /// Logical-stream creation rate limiter.
-    pub(super) stream_rate: RateState,
     /// Process shutdown admission latch.
     pub(super) closed: bool,
 }
@@ -135,6 +185,11 @@ pub(super) fn matching_profile(
                 && profile.user == expected.user
                 && profile.secret_mode == expected.secret_mode
                 && profile.carrier == expected.carrier
+                && profile.carrier_negotiation_enabled == expected.carrier_negotiation_enabled
+                && profile.carrier_learning == expected.carrier_learning
+                && profile.carriers == expected.carriers
+                && profile.carrier_negotiation_deadlines_secs
+                    == expected.carrier_negotiation_deadlines_secs
                 && profile.capability == expected.capability
                 && profile.key_fingerprint == expected.key_fingerprint
         })
@@ -198,6 +253,34 @@ pub(super) fn remove_bootstrap_locked(state: &mut ManagerState, hash: TokenHash)
     }
 }
 
+/// Retains one bounded host-bound marker for an invalidated session credential.
+pub(super) fn remember_closed_token_locked(
+    state: &mut ManagerState,
+    hash: TokenHash,
+    host: &str,
+    lifetime: Duration,
+    capacity: usize,
+) {
+    state.closed_tokens.insert(
+        hash,
+        ClosedToken {
+            expires_at: Instant::now() + lifetime,
+            host: host.to_string(),
+        },
+    );
+    while state.closed_tokens.len() > capacity {
+        let Some(oldest) = state
+            .closed_tokens
+            .iter()
+            .min_by_key(|(_, closed)| closed.expires_at)
+            .map(|(hash, _)| *hash)
+        else {
+            break;
+        };
+        state.closed_tokens.remove(&oldest);
+    }
+}
+
 /// Decrements one counted owner and removes its map entry at zero.
 pub(super) fn decrement_map<K, Q>(values: &mut HashMap<K, usize>, key: &Q)
 where
@@ -217,7 +300,7 @@ where
 
 /// Allocates a non-zero source port unique among live streams for one KDF route.
 pub(super) fn allocate_stream_port(
-    state: &mut ManagerState,
+    state: &mut StreamAdmissionState,
     client_ip: IpAddr,
     public_addr: SocketAddr,
 ) -> Option<u16> {
@@ -240,7 +323,7 @@ pub(super) fn allocate_stream_port(
 
 /// Releases one source port and reclaims empty per-route allocator state.
 pub(super) fn release_stream_port(
-    state: &mut ManagerState,
+    state: &mut StreamAdmissionState,
     client_ip: IpAddr,
     public_addr: SocketAddr,
     peer_port: u16,
@@ -262,7 +345,7 @@ mod tests {
 
     #[test]
     fn synthetic_ports_are_unique_per_live_route_and_state_is_reclaimed() {
-        let mut state = ManagerState::default();
+        let mut state = StreamAdmissionState::default();
         let client_ip = "192.0.2.10".parse().unwrap();
         let public_addr = "203.0.113.10:443".parse().unwrap();
         let first = allocate_stream_port(&mut state, client_ip, public_addr).unwrap();

src/web/manager/websocket.rs

@@ -1,7 +1,7 @@
 use std::collections::HashMap;
 use std::net::IpAddr;
 use std::sync::Arc;
-use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicU8, AtomicU64, Ordering};
 use std::time::Duration;
 
 use tokio::sync::OwnedSemaphorePermit;
@@ -10,7 +10,7 @@ use tokio_util::sync::CancellationToken;
 use super::{ManagerError, ProfileKey, WebProcessRuntime, WebSocketBudgetLease};
 
 /// One process-owned WebSocket carrier class used for eviction priority.
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub(crate) enum WebSocketKind {
     /// One connection multiplexes every logical stream in a session.
     Multiplex,
@@ -18,23 +18,42 @@ pub(crate) enum WebSocketKind {
     Lane(u32),
 }
 
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+struct WebSocketClaimKey {
+    session_hash: super::TokenHash,
+    kind: WebSocketKind,
+}
+
+#[repr(u8)]
+enum WebSocketPhase {
+    Claimed,
+    Upgraded,
+    Active,
+    Closing,
+}
+
 pub(super) struct WebSocketEntry {
     id: u64,
     owner: ProfileKey,
     session_id: u64,
+    claim: WebSocketClaimKey,
     client_ip: IpAddr,
     kind: WebSocketKind,
     liveness_interval_ms: u64,
     created_tick: u64,
     last_peer_tick: AtomicU64,
     last_progress_tick: AtomicU64,
-    opened: AtomicBool,
+    phase: AtomicU8,
+    closing: AtomicBool,
     cancel: CancellationToken,
+    released: CancellationToken,
 }
 
 #[derive(Default)]
 pub(super) struct WebSocketRegistry {
     entries: HashMap<u64, Arc<WebSocketEntry>>,
+    claims: HashMap<WebSocketClaimKey, u64>,
+    evictions_in_flight: usize,
     closed: bool,
 }
 
@@ -63,9 +82,45 @@ impl WebSocketConnection {
     }
 
     /// Marks successful ownership transfer from HTTP to the WebSocket codec.
-    pub(crate) fn mark_opened(&self) {
-        self.entry.opened.store(true, Ordering::Release);
+    pub(crate) fn mark_opened(&self) -> bool {
+        if self.entry.closing.load(Ordering::Acquire)
+            || self
+                .entry
+                .phase
+                .compare_exchange(
+                    WebSocketPhase::Claimed as u8,
+                    WebSocketPhase::Upgraded as u8,
+                    Ordering::AcqRel,
+                    Ordering::Acquire,
+                )
+                .is_err()
+            || self.entry.closing.load(Ordering::Acquire)
+        {
+            return false;
+        }
         self.mark_progress();
+        true
+    }
+
+    /// Marks the first validated carrier binary message as active progress.
+    pub(crate) fn mark_active(&self) -> bool {
+        if self.entry.closing.load(Ordering::Acquire)
+            || self
+                .entry
+                .phase
+                .compare_exchange(
+                    WebSocketPhase::Upgraded as u8,
+                    WebSocketPhase::Active as u8,
+                    Ordering::AcqRel,
+                    Ordering::Acquire,
+                )
+                .is_err()
+            || self.entry.closing.load(Ordering::Acquire)
+        {
+            return false;
+        }
+        self.mark_peer_activity();
+        true
     }
 
     /// Refreshes the peer-liveness deadline after any received WebSocket message.
@@ -90,93 +145,167 @@ impl WebSocketConnection {
 impl Drop for WebSocketConnection {
     fn drop(&mut self) {
         if let Some(runtime) = self.runtime.upgrade() {
-            runtime.websockets.lock().entries.remove(&self.entry.id);
+            let mut registry = runtime.websockets.lock();
+            registry.entries.remove(&self.entry.id);
+            if registry.claims.get(&self.entry.claim) == Some(&self.entry.id) {
+                registry.claims.remove(&self.entry.claim);
+            }
+            if self.entry.closing.load(Ordering::Acquire) {
+                if registry.evictions_in_flight == 0 {
+                    registry.closed = true;
+                } else {
+                    registry.evictions_in_flight -= 1;
+                }
+            }
+            drop(registry);
             drop(self.base_budget.take());
             drop(self.slot.take());
+            self.entry.released.cancel();
             runtime.websocket_notify.notify_waiters();
         }
     }
 }
 
+#[allow(clippy::too_many_arguments)]
 pub(super) async fn admit(
     runtime: &Arc<WebProcessRuntime>,
     owner: ProfileKey,
     session_id: u64,
+    session_hash: super::TokenHash,
     client_ip: IpAddr,
     kind: WebSocketKind,
     base_bytes: usize,
     liveness_interval: Duration,
     eviction_timeout: Duration,
+    parent_cancellation: CancellationToken,
 ) -> Result<WebSocketConnection, ManagerError> {
+    if parent_cancellation.is_cancelled() {
+        return Err(ManagerError::Closed);
+    }
     let liveness_interval_ms = liveness_interval.as_millis().min(u128::from(u64::MAX)) as u64;
-    if let Some(connection) = try_admit(
+    match try_admit(
         runtime,
         owner,
         session_id,
+        session_hash,
         client_ip,
         kind,
         base_bytes,
         liveness_interval_ms,
+        &parent_cancellation,
     ) {
-        return Ok(connection);
+        Ok(connection) => return Ok(connection),
+        Err(TryAdmitError::Conflict) => return Err(ManagerError::Concurrent),
+        Err(TryAdmitError::Closed) => return Err(ManagerError::Closed),
+        Err(TryAdmitError::Capacity) => {}
     }
-    let Some(victim) = select_victim(runtime, owner, session_id, client_ip, None) else {
+    let Some(victim) = select_victim(runtime, owner, session_id, client_ip, None, true) else {
         runtime.record_limit_hit();
         return Err(ManagerError::Limit);
     };
-    let released = runtime.websocket_notify.notified();
+    let released = victim.released.cancelled();
     victim.cancel.cancel();
-    let _ = tokio::time::timeout(eviction_timeout, released).await;
-    try_admit(
+    tokio::select! {
+        _ = parent_cancellation.cancelled() => return Err(ManagerError::Closed),
+        _ = tokio::time::timeout(eviction_timeout, released) => {}
+    }
+    if parent_cancellation.is_cancelled() {
+        return Err(ManagerError::Closed);
+    }
+    match try_admit(
         runtime,
         owner,
         session_id,
+        session_hash,
         client_ip,
         kind,
         base_bytes,
         liveness_interval_ms,
-    )
-    .ok_or_else(|| {
+        &parent_cancellation,
+    ) {
+        Ok(connection) => Ok(connection),
+        Err(TryAdmitError::Conflict) => Err(ManagerError::Concurrent),
+        Err(TryAdmitError::Closed) => Err(ManagerError::Closed),
+        Err(TryAdmitError::Capacity) => {
             runtime.record_limit_hit();
-        ManagerError::Limit
-    })
+            Err(ManagerError::Limit)
+        }
+    }
+}
+
+enum TryAdmitError {
+    Capacity,
+    Conflict,
+    Closed,
 }
 
 fn try_admit(
     runtime: &Arc<WebProcessRuntime>,
     owner: ProfileKey,
     session_id: u64,
+    session_hash: super::TokenHash,
     client_ip: IpAddr,
     kind: WebSocketKind,
     base_bytes: usize,
     liveness_interval_ms: u64,
-) -> Option<WebSocketConnection> {
+    parent_cancellation: &CancellationToken,
+) -> Result<WebSocketConnection, TryAdmitError> {
+    if parent_cancellation.is_cancelled() {
+        return Err(TryAdmitError::Closed);
+    }
+    let claim = WebSocketClaimKey { session_hash, kind };
+    {
+        let registry = runtime.websockets.lock();
+        if registry.closed {
+            return Err(TryAdmitError::Closed);
+        }
+        if registry.claims.contains_key(&claim) {
+            return Err(TryAdmitError::Conflict);
+        }
+    }
     let slot = Arc::clone(&runtime.websocket_connections)
         .try_acquire_owned()
-        .ok()?;
-    let base_budget = runtime.try_websocket_base_budget(owner, base_bytes)?;
-    let id = runtime.websocket_next_id.fetch_add(1, Ordering::Relaxed);
+        .map_err(|_| TryAdmitError::Capacity)?;
+    let base_budget = runtime
+        .try_websocket_base_budget(owner, base_bytes)
+        .ok_or(TryAdmitError::Capacity)?;
+    if parent_cancellation.is_cancelled() {
+        return Err(TryAdmitError::Closed);
+    }
+    let id = runtime
+        .websocket_next_id
+        .fetch_update(Ordering::AcqRel, Ordering::Acquire, |value| {
+            value.checked_add(1)
+        })
+        .map_err(|_| TryAdmitError::Capacity)?;
     let now = runtime.websocket_tick();
     let entry = Arc::new(WebSocketEntry {
         id,
         owner,
         session_id,
+        claim,
         client_ip,
         kind,
         liveness_interval_ms,
         created_tick: now,
         last_peer_tick: AtomicU64::new(now),
         last_progress_tick: AtomicU64::new(now),
-        opened: AtomicBool::new(false),
-        cancel: CancellationToken::new(),
+        phase: AtomicU8::new(WebSocketPhase::Claimed as u8),
+        closing: AtomicBool::new(false),
+        cancel: parent_cancellation.child_token(),
+        released: CancellationToken::new(),
     });
     let mut registry = runtime.websockets.lock();
-    if registry.closed {
-        return None;
+    if registry.closed || parent_cancellation.is_cancelled() {
+        return Err(TryAdmitError::Closed);
     }
+    if registry.claims.contains_key(&claim) {
+        return Err(TryAdmitError::Conflict);
+    }
+    registry.claims.insert(claim, id);
     registry.entries.insert(id, Arc::clone(&entry));
     drop(registry);
-    Some(WebSocketConnection {
+    Ok(WebSocketConnection {
         runtime: Arc::downgrade(runtime),
         entry,
         slot: Some(slot),
@@ -191,22 +320,13 @@ impl WebProcessRuntime {
 
     pub(super) fn cleanup_websockets(&self) {
         let now = self.websocket_tick();
-        let mut victims = self
-            .websockets
-            .lock()
-            .entries
-            .values()
-            .filter(|entry| {
-                now.saturating_sub(entry.last_peer_tick.load(Ordering::Acquire))
-                    >= dead_after(entry)
-            })
-            .cloned()
-            .collect::<Vec<_>>();
-        if victims.is_empty()
-            && self.data_budget.take_pressure()
-            && let Some(victim) = select_pressure_victim(self, now)
-        {
+        let mut victims = claim_stale_victims(self, now);
+        if victims.is_empty() && self.data_budget.take_pressure() {
+            if let Some(victim) = select_pressure_victim(self, now, true) {
                 victims.push(victim);
+            } else {
+                self.data_budget.restore_pressure();
+            }
         }
         for victim in victims {
             victim.cancel.cancel();
@@ -231,16 +351,20 @@ fn select_victim(
     session_id: u64,
     client_ip: IpAddr,
     excluded_id: Option<u64>,
+    claim: bool,
 ) -> Option<Arc<WebSocketEntry>> {
     let fair_share = runtime.data_budget.fair_share(Some(owner));
     let requester_usage = runtime.data_budget.owner_usage(owner);
     let now = runtime.websocket_tick();
-    runtime
-        .websockets
-        .lock()
+    let mut registry = runtime.websockets.lock();
+    if claim && registry.evictions_in_flight >= runtime.limits.max_websocket_evictions_in_flight {
+        return None;
+    }
+    let selected = registry
         .entries
         .values()
         .filter(|entry| Some(entry.id) != excluded_id)
+        .filter(|entry| !entry.closing.load(Ordering::Acquire))
         .filter_map(|entry| {
             let owner_rank = if entry.session_id == session_id {
                 0
@@ -269,15 +393,26 @@ fn select_victim(
             ))
         })
         .min_by_key(|(key, _)| *key)
-        .map(|(_, entry)| entry)
+        .map(|(_, entry)| entry)?;
+    if claim && !claim_entry(&mut registry, &selected, runtime) {
+        return None;
+    }
+    Some(selected)
 }
 
-fn select_pressure_victim(runtime: &WebProcessRuntime, now: u64) -> Option<Arc<WebSocketEntry>> {
-    runtime
-        .websockets
-        .lock()
+fn select_pressure_victim(
+    runtime: &WebProcessRuntime,
+    now: u64,
+    claim: bool,
+) -> Option<Arc<WebSocketEntry>> {
+    let mut registry = runtime.websockets.lock();
+    if claim && registry.evictions_in_flight >= runtime.limits.max_websocket_evictions_in_flight {
+        return None;
+    }
+    let selected = registry
         .entries
         .values()
+        .filter(|entry| !entry.closing.load(Ordering::Acquire))
         .map(|entry| {
             (
                 (
@@ -290,11 +425,57 @@ fn select_pressure_victim(runtime: &WebProcessRuntime, now: u64) -> Option<Arc<W
             )
         })
         .min_by_key(|(key, _)| *key)
-        .map(|(_, entry)| entry)
+        .map(|(_, entry)| entry)?;
+    if claim && !claim_entry(&mut registry, &selected, runtime) {
+        return None;
+    }
+    Some(selected)
+}
+
+fn claim_stale_victims(runtime: &WebProcessRuntime, now: u64) -> Vec<Arc<WebSocketEntry>> {
+    let mut registry = runtime.websockets.lock();
+    let available = runtime
+        .limits
+        .max_websocket_evictions_in_flight
+        .saturating_sub(registry.evictions_in_flight);
+    let candidates = registry
+        .entries
+        .values()
+        .filter(|entry| !entry.closing.load(Ordering::Acquire))
+        .filter(|entry| {
+            now.saturating_sub(entry.last_peer_tick.load(Ordering::Acquire)) >= dead_after(entry)
+        })
+        .take(available)
+        .cloned()
+        .collect::<Vec<_>>();
+    candidates
+        .into_iter()
+        .filter(|entry| claim_entry(&mut registry, entry, runtime))
+        .collect()
+}
+
+fn claim_entry(
+    registry: &mut WebSocketRegistry,
+    entry: &Arc<WebSocketEntry>,
+    runtime: &WebProcessRuntime,
+) -> bool {
+    if registry.evictions_in_flight >= runtime.limits.max_websocket_evictions_in_flight
+        || entry
+            .closing
+            .compare_exchange(false, true, Ordering::AcqRel, Ordering::Acquire)
+            .is_err()
+    {
+        return false;
+    }
+    entry
+        .phase
+        .store(WebSocketPhase::Closing as u8, Ordering::Release);
+    registry.evictions_in_flight += 1;
+    true
 }
 
 fn entry_priority(entry: &WebSocketEntry, now: u64) -> u8 {
-    if !entry.opened.load(Ordering::Acquire)
+    if entry.phase.load(Ordering::Acquire) < WebSocketPhase::Active as u8
         || now.saturating_sub(entry.last_peer_tick.load(Ordering::Acquire)) >= dead_after(entry)
     {
         0

src/web/manager/websocket/tests.rs

@@ -1,18 +1,29 @@
 use super::*;
 
 fn entry(kind: WebSocketKind, opened: bool, peer_tick: u64) -> WebSocketEntry {
+    let phase = if opened {
+        WebSocketPhase::Active
+    } else {
+        WebSocketPhase::Claimed
+    };
     WebSocketEntry {
         id: 1,
         owner: [0; 32],
         session_id: 1,
+        claim: WebSocketClaimKey {
+            session_hash: [0; 32],
+            kind,
+        },
         client_ip: "192.0.2.10".parse().unwrap(),
         kind,
         liveness_interval_ms: 10,
         created_tick: 1,
         last_peer_tick: AtomicU64::new(peer_tick),
         last_progress_tick: AtomicU64::new(peer_tick),
-        opened: AtomicBool::new(opened),
+        phase: AtomicU8::new(phase as u8),
+        closing: AtomicBool::new(false),
         cancel: CancellationToken::new(),
+        released: CancellationToken::new(),
     }
 }
 

src/web/session.rs

@@ -2,9 +2,9 @@ use std::collections::{HashMap, HashSet, VecDeque};
 use std::io;
 use std::net::IpAddr;
 use std::sync::Arc;
-use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicUsize};
 use std::task::{Context, Poll, Waker};
-use std::time::{Duration, Instant};
+use std::time::Instant;
 
 use bytes::{Bytes, BytesMut};
 use parking_lot::Mutex;
@@ -14,17 +14,30 @@ use tokio_util::sync::CancellationToken;
 
 use crate::config::{WebCarrier, WebLimitsConfig, WebRuntimeProfile, WebTimeoutsConfig};
 use crate::web::frame::{self, FrameType};
-use crate::web::manager::{ProfileKey, TokenHash, WebProcessRuntime};
+use crate::web::manager::{
+    CarrierClientClass, CarrierLearningContext, ProfileKey, TokenHash, WebProcessRuntime,
+};
 
 // Backend tasks own generation admission and authenticated MTProxy relay lifetimes.
 mod backend;
 // Downlink queues own cursor replay, flow control, and memory reservations.
 mod downlink;
+// Response ownership keeps detached batches charged until the last body clone drops.
+mod resident;
 // Lane carrier state isolates request sequencing and downlink replay per logical stream.
 mod lanes;
+// Lane batch staging transfers queue ownership without escaping process budgets.
+mod lane_downlink;
+// Lane uplink creation remains transactional across validation and queue reservations.
+mod lane_uplink;
 // WebSocket carrier state owns pre-OPEN lane reservations and failure isolation.
 mod websocket;
 pub(crate) use websocket::WebSocketLaneReservation;
+pub(crate) use websocket::WebSocketProbeReservation;
+// Carrier commit and health evidence share one session-locked state machine.
+mod negotiation;
+// Session closure and carrier-attempt transitions share one cancellation boundary.
+mod lifecycle;
 // Uplink batches own exactly-once sequencing and client-frame validation.
 mod uplink;
 
@@ -43,7 +56,14 @@ struct InboundChunk {
     offset: usize,
 }
 
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) struct StreamIdentity {
+    pub(crate) id: u32,
+    pub(crate) instance: u64,
+}
+
 struct StreamState {
+    instance: u64,
     inbound: VecDeque<InboundChunk>,
     receive_window: u32,
     send_credit: u64,
@@ -61,15 +81,21 @@ struct QueuedFrame {
 
 struct DownBatch {
     body: Bytes,
+    lease: Arc<resident::PendingResponseLease>,
     base_cursor: u64,
     next_cursor: u64,
     data_bytes: usize,
     data_items: usize,
     control_bytes: usize,
     control_items: usize,
+    carrier_health_eligible: bool,
 }
 
 struct CarrierLane {
+    instance: u64,
+    pending_bytes: usize,
+    pending_items: usize,
+    resident: Arc<resident::ResidentCounters>,
     pending_frames: VecDeque<QueuedFrame>,
     pending_windows: HashMap<u32, usize>,
     unacked: Option<DownBatch>,
@@ -82,8 +108,12 @@ struct CarrierLane {
 }
 
 impl CarrierLane {
-    fn new() -> Self {
+    fn new(instance: u64) -> Self {
         Self {
+            instance,
+            pending_bytes: 0,
+            pending_items: 0,
+            resident: Arc::new(resident::ResidentCounters::default()),
             pending_frames: VecDeque::new(),
             pending_windows: HashMap::new(),
             unacked: None,
@@ -99,6 +129,8 @@ impl CarrierLane {
 
 struct SessionState {
     streams: HashMap<u32, StreamState>,
+    closing_streams: HashMap<u32, u64>,
+    next_stream_instance: u64,
     active_peer_ports: HashSet<u16>,
     closed_streams: HashSet<u32>,
     closed_order: VecDeque<u32>,
@@ -110,15 +142,38 @@ struct SessionState {
     last_up_sequence: u64,
     last_up_digest: TokenHash,
     carrier_lanes: HashMap<u32, CarrierLane>,
+    lane_open_waits: usize,
+    next_lane_instance: u64,
     websocket_lane_reservations: HashMap<u32, u16>,
     pending_bytes: usize,
     pending_items: usize,
     pending_control_bytes: usize,
     pending_control_items: usize,
     last_activity: Instant,
+    negotiation_phase: SessionNegotiationPhase,
+    carrier_health_due_at: Option<Instant>,
+    carrier_health_activity_at: Option<Instant>,
+    carrier_health_uplink: bool,
+    carrier_health_downlink: bool,
+    carrier_commit_published: bool,
+    carrier_health_reported: bool,
+    websocket_carrier_active: bool,
+    websocket_commit_ack_pending: bool,
+    websocket_commit_ack_owner: Option<u64>,
+    websocket_commit_ack_written: bool,
+    websocket_probe_claimed: bool,
+    close_requested: bool,
     closed: bool,
 }
 
+#[derive(Clone, Copy, PartialEq, Eq)]
+enum SessionNegotiationPhase {
+    Uncommitted,
+    Replacing,
+    Committed,
+    Superseded,
+}
+
 /// One bounded WEB carrier session containing logical MTProxy streams.
 pub(crate) struct WebSession {
     manager: std::sync::Weak<WebProcessRuntime>,
@@ -127,13 +182,22 @@ pub(crate) struct WebSession {
     trace_session_id: u64,
     profile: Arc<WebRuntimeProfile>,
     profile_key: ProfileKey,
+    selected_carrier: WebCarrier,
+    carrier_attempt: u8,
+    bootstrap_hash: TokenHash,
+    carrier_deadline_at: Option<Instant>,
+    carrier_class: CarrierClientClass,
+    learning_context: Option<CarrierLearningContext>,
+    automatic_carrier: bool,
     limits: WebLimitsConfig,
     timeouts: WebTimeoutsConfig,
     state: Mutex<SessionState>,
     down_notify: Arc<Notify>,
+    lane_open_notify: Arc<Notify>,
     cancel: CancellationToken,
     tasks_live: AtomicUsize,
     tasks_done: Arc<Notify>,
+    resident: Arc<resident::ResidentCounters>,
     finished: AtomicBool,
     up_active: AtomicBool,
 }
@@ -158,12 +222,21 @@ impl WebSession {
         trace_session_id: u64,
         profile: Arc<WebRuntimeProfile>,
         profile_key: ProfileKey,
+        selected_carrier: WebCarrier,
+        carrier_attempt: u8,
+        bootstrap_hash: TokenHash,
+        carrier_deadline_at: Option<Instant>,
+        carrier_class: CarrierClientClass,
+        learning_context: Option<CarrierLearningContext>,
+        automatic_carrier: bool,
         limits: WebLimitsConfig,
         timeouts: WebTimeoutsConfig,
     ) -> Arc<Self> {
         let mut carrier_lanes = HashMap::new();
-        if profile.carrier == WebCarrier::HttpsLanes {
-            carrier_lanes.insert(0, CarrierLane::new());
+        let mut next_lane_instance = 1;
+        if selected_carrier == WebCarrier::HttpsLanes {
+            carrier_lanes.insert(0, CarrierLane::new(next_lane_instance));
+            next_lane_instance += 1;
         }
         Arc::new(Self {
             manager,
@@ -172,10 +245,19 @@ impl WebSession {
             trace_session_id,
             profile,
             profile_key,
+            selected_carrier,
+            carrier_attempt,
+            bootstrap_hash,
+            carrier_deadline_at,
+            carrier_class,
+            learning_context,
+            automatic_carrier,
             limits,
             timeouts,
             state: Mutex::new(SessionState {
                 streams: HashMap::new(),
+                closing_streams: HashMap::new(),
+                next_stream_instance: 1,
                 active_peer_ports: HashSet::new(),
                 closed_streams: HashSet::new(),
                 closed_order: VecDeque::new(),
@@ -187,18 +269,35 @@ impl WebSession {
                 last_up_sequence: 0,
                 last_up_digest: [0; 32],
                 carrier_lanes,
+                lane_open_waits: 0,
+                next_lane_instance,
                 websocket_lane_reservations: HashMap::new(),
                 pending_bytes: 0,
                 pending_items: 0,
                 pending_control_bytes: 0,
                 pending_control_items: 0,
                 last_activity: Instant::now(),
+                negotiation_phase: SessionNegotiationPhase::Uncommitted,
+                carrier_health_due_at: None,
+                carrier_health_activity_at: None,
+                carrier_health_uplink: false,
+                carrier_health_downlink: false,
+                carrier_commit_published: false,
+                carrier_health_reported: false,
+                websocket_carrier_active: false,
+                websocket_commit_ack_pending: false,
+                websocket_commit_ack_owner: None,
+                websocket_commit_ack_written: false,
+                websocket_probe_claimed: false,
+                close_requested: false,
                 closed: false,
             }),
             down_notify: Arc::new(Notify::new()),
+            lane_open_notify: Arc::new(Notify::new()),
             cancel: CancellationToken::new(),
             tasks_live: AtomicUsize::new(0),
             tasks_done: Arc::new(Notify::new()),
+            resident: Arc::new(resident::ResidentCounters::default()),
             finished: AtomicBool::new(false),
             up_active: AtomicBool::new(false),
         })
@@ -216,7 +315,7 @@ impl WebSession {
 
     /// Returns the immutable carrier selected when this session was created.
     pub(crate) fn carrier(&self) -> WebCarrier {
-        self.profile.carrier
+        self.selected_carrier
     }
 
     /// Returns the stable quota owner without exposing profile credentials.
@@ -229,6 +328,11 @@ impl WebSession {
         self.trace_session_id
     }
 
+    /// Creates a child cancellation boundary for one owned carrier task.
+    pub(crate) fn carrier_cancellation(&self) -> CancellationToken {
+        self.cancel.child_token()
+    }
+
     /// Returns a cloned non-secret identity only for enabled debug capture.
     pub(crate) fn trace_identity(&self) -> crate::web::trace::TraceIdentity {
         crate::web::trace::TraceIdentity::from_profile(self.trace_session_id, &self.profile)
@@ -253,96 +357,34 @@ impl WebSession {
         }
     }
 
-    /// Closes carrier state while relay tasks retain their admission until exit.
-    pub(crate) fn close(&self) {
-        let (data_bytes, data_items, control_bytes, control_items) = {
-            let mut state = self.state.lock();
-            if state.closed {
-                return;
-            }
-            state.closed = true;
-            for stream in state.streams.values_mut() {
-                if let Some(waker) = stream.read_waker.take() {
-                    waker.wake();
-                }
-                if let Some(waker) = stream.write_waker.take() {
-                    waker.wake();
-                }
-            }
-            state.streams.clear();
-            state.pending_frames.clear();
-            state.pending_windows.clear();
-            state.unacked = None;
-            for lane in state.carrier_lanes.values() {
-                lane.notify.notify_waiters();
-            }
-            state.carrier_lanes.clear();
-            let control_bytes = state.pending_control_bytes;
-            let control_items = state.pending_control_items;
-            let data_bytes = state.pending_bytes.saturating_sub(control_bytes);
-            let data_items = state.pending_items.saturating_sub(control_items);
-            state.pending_bytes = 0;
-            state.pending_items = 0;
-            state.pending_control_bytes = 0;
-            state.pending_control_items = 0;
-            (data_bytes, data_items, control_bytes, control_items)
-        };
-        self.cancel.cancel();
-        if self.carrier().is_multiplexed() {
-            self.down_notify.notify_waiters();
-        }
-        if let Some(manager) = self.manager.upgrade() {
-            manager.release_pending(self.profile_key, data_bytes, data_items, false);
-            manager.release_pending(self.profile_key, control_bytes, control_items, true);
-            if !self.finished.swap(true, Ordering::AcqRel) {
-                self.trace_lifecycle(
-                    crate::web::trace::TraceLifecycleEvent::SessionClosed,
-                    None,
-                    Some("closed"),
-                );
-                manager.session_finished(
-                    self.token_hash,
-                    self.client_ip,
-                    self.profile_key,
-                    &self.profile.host,
-                );
-            }
-        }
+    /// Returns the immutable limits frozen when this carrier chain was created.
+    pub(crate) fn limits(&self) -> &WebLimitsConfig {
+        &self.limits
     }
 
-    /// Waits for all logical-stream tasks after admission has closed.
-    pub(crate) async fn wait(&self) {
-        loop {
-            let notified = self.tasks_done.notified();
-            if self.tasks_live.load(Ordering::Acquire) == 0 {
-                return;
-            }
-            notified.await;
-        }
-    }
-
-    /// Returns whether reconnect grace elapsed without activity.
-    pub(crate) fn is_idle(&self, now: Instant) -> bool {
-        let state = self.state.lock();
-        !state.closed
-            && now.saturating_duration_since(state.last_activity)
-                >= Duration::from_secs(self.timeouts.reconnect_grace_secs)
+    /// Returns the immutable timeouts frozen when this carrier chain was created.
+    pub(crate) fn timeouts(&self) -> &WebTimeoutsConfig {
+        &self.timeouts
     }
 
     /// Polls client-to-server bytes and returns consumed flow-control credit.
     pub(super) fn poll_read(
         &self,
-        stream_id: u32,
+        stream: StreamIdentity,
         cx: &mut Context<'_>,
         output: &mut ReadBuf<'_>,
     ) -> Poll<io::Result<()>> {
         let mut state = self.state.lock();
         let (count, finished) = {
-            let Some(stream) = state.streams.get_mut(&stream_id) else {
+            let Some(stream_state) = state
+                .streams
+                .get_mut(&stream.id)
+                .filter(|state| state.instance == stream.instance)
+            else {
                 return Poll::Ready(Ok(()));
             };
-            let Some(chunk) = stream.inbound.front_mut() else {
-                stream.read_waker = Some(cx.waker().clone());
+            let Some(chunk) = stream_state.inbound.front_mut() else {
+                stream_state.read_waker = Some(cx.waker().clone());
                 return Poll::Pending;
             };
             let available = &chunk.bytes[chunk.offset..];
@@ -351,14 +393,14 @@ impl WebSession {
             chunk.offset += count;
             let finished = chunk.offset == chunk.bytes.len();
             if finished {
-                stream.inbound.pop_front();
+                stream_state.inbound.pop_front();
             }
-            stream.receive_window = stream.receive_window.saturating_add(count as u32);
+            stream_state.receive_window = stream_state.receive_window.saturating_add(count as u32);
             (count, finished)
         };
         let overhead = if finished { QUEUE_ITEM_COST } else { 0 };
         self.release_locked(&mut state, count + overhead, usize::from(finished), false);
-        if !self.queue_window_locked(&mut state, stream_id, count as u32) {
+        if !self.queue_window_locked(&mut state, stream.id, count as u32) {
             drop(state);
             self.close();
             return Poll::Ready(Err(io::Error::other(
@@ -371,7 +413,7 @@ impl WebSession {
     /// Polls server-to-client writes against stream credit and bounded queues.
     pub(super) fn poll_write(
         &self,
-        stream_id: u32,
+        stream: StreamIdentity,
         cx: &mut Context<'_>,
         input: &[u8],
     ) -> Poll<io::Result<usize>> {
@@ -379,7 +421,11 @@ impl WebSession {
             return Poll::Ready(Ok(0));
         }
         let mut state = self.state.lock();
-        let Some(stream) = state.streams.get_mut(&stream_id) else {
+        let Some(stream_state) = state
+            .streams
+            .get_mut(&stream.id)
+            .filter(|state| state.instance == stream.instance)
+        else {
             return Poll::Ready(Err(io::Error::new(
                 io::ErrorKind::BrokenPipe,
                 "WEB logical stream is closed",
@@ -389,24 +435,39 @@ impl WebSession {
             .len()
             .min(frame::DATA_CHUNK_BYTES)
             .min(self.limits.max_frame_payload_bytes)
-            .min(stream.send_credit as usize);
+            .min(if self.carrier().uses_lanes() {
+                self.limits
+                    .pending_bytes_per_lane
+                    .saturating_sub(frame::HEADER_BYTES + QUEUE_ITEM_COST)
+            } else {
+                usize::MAX
+            })
+            .min(stream_state.send_credit as usize);
         if count == 0 {
-            stream.write_waker = Some(cx.waker().clone());
+            stream_state.write_waker = Some(cx.waker().clone());
             return Poll::Pending;
         }
-        if !self.queue_data_locked(&mut state, stream_id, &input[..count]) {
-            if let Some(stream) = state.streams.get_mut(&stream_id) {
-                stream.write_waker = Some(cx.waker().clone());
+        if !self.queue_data_locked(&mut state, stream.id, &input[..count]) {
+            if let Some(stream_state) = state
+                .streams
+                .get_mut(&stream.id)
+                .filter(|state| state.instance == stream.instance)
+            {
+                stream_state.write_waker = Some(cx.waker().clone());
             }
             return Poll::Pending;
         }
-        let Some(stream) = state.streams.get_mut(&stream_id) else {
+        let Some(stream_state) = state
+            .streams
+            .get_mut(&stream.id)
+            .filter(|state| state.instance == stream.instance)
+        else {
             return Poll::Ready(Err(io::Error::new(
                 io::ErrorKind::BrokenPipe,
                 "WEB logical stream is closed",
             )));
         };
-        stream.send_credit -= count as u64;
+        stream_state.send_credit -= count as u64;
         state.last_activity = Instant::now();
         drop(state);
         if self.carrier().is_multiplexed() {
@@ -421,18 +482,6 @@ impl WebSession {
             .upgrade()
             .map(|manager| manager.budget_notify())
     }
-
-    fn release_stream_reservation(&self, peer_port: u16) {
-        let removed = self.state.lock().active_peer_ports.remove(&peer_port);
-        if removed && let Some(manager) = self.manager.upgrade() {
-            manager.release_stream(
-                self.profile_key,
-                self.client_ip,
-                self.profile.public_addr,
-                peer_port,
-            );
-        }
-    }
 }
 
 fn inbound_queue_cost(queue: &VecDeque<InboundChunk>) -> (usize, usize) {
@@ -456,3 +505,12 @@ fn remember_closed(state: &mut SessionState, stream_id: u32, limit: usize) -> Op
     }
     evicted
 }
+
+fn insert_carrier_lane(state: &mut SessionState, lane_id: u32) -> Option<u64> {
+    let instance = state.next_lane_instance;
+    state.next_lane_instance = instance.checked_add(1)?;
+    state
+        .carrier_lanes
+        .insert(lane_id, CarrierLane::new(instance));
+    Some(instance)
+}

src/web/session/backend.rs

@@ -7,7 +7,7 @@ use crate::proxy::shared_state::ConntrackClosePolicy;
 use crate::web::frame::FrameType;
 use crate::web::stream::WebLogicalStream;
 
-use super::{WebSession, inbound_queue_cost};
+use super::{StreamIdentity, WebSession, inbound_queue_cost};
 
 #[cfg(test)]
 #[path = "backend_tests.rs"]
@@ -17,61 +17,64 @@ impl WebSession {
     /// Starts one owned inner handshake and relay task for an admitted stream.
     pub(super) fn spawn_stream(
         self: &Arc<Self>,
-        stream_id: u32,
-        peer_port: u16,
+        completion: StreamCompletion,
         retain_reservation_on_reject: bool,
     ) -> bool {
+        let stream = completion.stream;
+        let peer_port = completion.peer_port;
         let Some(manager) = self.manager.upgrade() else {
-            self.stream_rejected_before_spawn(stream_id, peer_port, retain_reservation_on_reject);
+            completion
+                .retain_rejected
+                .store(retain_reservation_on_reject, Ordering::Release);
+            drop(completion);
             return false;
         };
         let generation = manager.active_generation();
         if !*generation.admission_rx.borrow() {
             self.trace_lifecycle(
                 crate::web::trace::TraceLifecycleEvent::StreamRejected,
-                Some(stream_id),
+                Some(stream.id),
                 Some("admission_closed"),
             );
-            self.stream_rejected_before_spawn(stream_id, peer_port, retain_reservation_on_reject);
+            completion
+                .retain_rejected
+                .store(retain_reservation_on_reject, Ordering::Release);
+            drop(completion);
             return false;
         }
         let Ok(connection_permit) = generation.max_connections.clone().try_acquire_owned() else {
             manager.record_stream_rejected();
             self.trace_lifecycle(
                 crate::web::trace::TraceLifecycleEvent::StreamRejected,
-                Some(stream_id),
+                Some(stream.id),
                 Some("connection_limit"),
             );
-            self.stream_rejected_before_spawn(stream_id, peer_port, retain_reservation_on_reject);
+            completion
+                .retain_rejected
+                .store(retain_reservation_on_reject, Ordering::Release);
+            drop(completion);
             return false;
         };
         let deps = generation.client_runtime_deps();
         let replay_checker = Arc::clone(&generation.replay_checker);
         let session = Arc::clone(self);
         let cancel = self.cancel.clone();
-        let retain_rejected = Arc::new(AtomicBool::new(false));
-        self.tasks_live.fetch_add(1, Ordering::AcqRel);
-        let completion = StreamCompletion {
-            session: Arc::clone(&session),
-            stream_id,
-            peer_port,
-            retain_rejected: Arc::clone(&retain_rejected),
-        };
+        let retain_rejected = Arc::clone(&completion.retain_rejected);
         let future = async move {
             let _connection_permit = connection_permit;
             let _completion = completion;
             session.trace_lifecycle(
                 crate::web::trace::TraceLifecycleEvent::StreamAdmitted,
-                Some(stream_id),
+                Some(stream.id),
                 None,
             );
-            let stream = WebLogicalStream::new(Arc::clone(&session), stream_id);
+            let logical_stream = WebLogicalStream::new(Arc::clone(&session), stream);
             tokio::select! {
                 _ = cancel.cancelled() => {}
                 _ = run_stream(
                     Arc::clone(&session),
-                    stream_id,
                     stream,
+                    logical_stream,
                     deps,
                     replay_checker,
                     peer_port,
@@ -82,7 +85,7 @@ impl WebSession {
             retain_rejected.store(retain_reservation_on_reject, Ordering::Release);
             self.trace_lifecycle(
                 crate::web::trace::TraceLifecycleEvent::StreamRejected,
-                Some(stream_id),
+                Some(stream.id),
                 Some("generation_closed"),
             );
             drop(future);
@@ -93,21 +96,32 @@ impl WebSession {
 
     fn stream_rejected_before_spawn(
         &self,
-        stream_id: u32,
+        stream: StreamIdentity,
         peer_port: u16,
         retain_reservation: bool,
     ) {
         if !retain_reservation {
-            self.stream_finished(stream_id, peer_port);
+            self.stream_finished(stream, peer_port);
             return;
         }
         let queued = {
             let mut state = self.state.lock();
-            state.streams.remove(&stream_id).map(|stream| {
-                let (bytes, items) = inbound_queue_cost(&stream.inbound);
+            if state.closing_streams.get(&stream.id) == Some(&stream.instance) {
+                state.closing_streams.remove(&stream.id);
+                self.remember_closed_locked(&mut state, stream.id);
+            }
+            state
+                .streams
+                .get(&stream.id)
+                .filter(|state| state.instance == stream.instance)
+                .is_some()
+                .then(|| state.streams.remove(&stream.id))
+                .flatten()
+                .map(|stream_state| {
+                    let (bytes, items) = inbound_queue_cost(&stream_state.inbound);
                     self.release_locked(&mut state, bytes, items, false);
-                self.remember_closed_locked(&mut state, stream_id);
-                self.queue_control_locked(&mut state, FrameType::Close, stream_id, &[])
+                    self.remember_closed_locked(&mut state, stream.id);
+                    self.queue_control_locked(&mut state, FrameType::Close, stream.id, &[])
                 })
         };
         if queued.is_some_and(|queued| !queued) {
@@ -115,16 +129,27 @@ impl WebSession {
         }
     }
 
-    fn stream_finished(&self, stream_id: u32, peer_port: u16) {
+    fn stream_finished(&self, stream: StreamIdentity, peer_port: u16) {
         let (queued, reserved) = {
             let mut state = self.state.lock();
             let reserved = state.active_peer_ports.remove(&peer_port);
-            let queued = state.streams.remove(&stream_id).map(|stream| {
-                let (bytes, items) = inbound_queue_cost(&stream.inbound);
+            let current = state
+                .streams
+                .get(&stream.id)
+                .is_some_and(|state| state.instance == stream.instance);
+            let queued = current
+                .then(|| state.streams.remove(&stream.id))
+                .flatten()
+                .map(|stream_state| {
+                    let (bytes, items) = inbound_queue_cost(&stream_state.inbound);
                     self.release_locked(&mut state, bytes, items, false);
-                self.remember_closed_locked(&mut state, stream_id);
-                self.queue_control_locked(&mut state, FrameType::Close, stream_id, &[])
+                    self.remember_closed_locked(&mut state, stream.id);
+                    self.queue_control_locked(&mut state, FrameType::Close, stream.id, &[])
                 });
+            if state.closing_streams.get(&stream.id) == Some(&stream.instance) {
+                state.closing_streams.remove(&stream.id);
+                self.remember_closed_locked(&mut state, stream.id);
+            }
             (queued, reserved)
         };
         if reserved && let Some(manager) = self.manager.upgrade() {
@@ -146,25 +171,41 @@ impl WebSession {
     }
 }
 
-struct StreamCompletion {
+pub(super) struct StreamCompletion {
     session: Arc<WebSession>,
-    stream_id: u32,
-    peer_port: u16,
+    pub(super) stream: StreamIdentity,
+    pub(super) peer_port: u16,
     retain_rejected: Arc<AtomicBool>,
 }
 
+impl WebSession {
+    pub(super) fn own_stream_task(
+        self: &Arc<Self>,
+        stream: StreamIdentity,
+        peer_port: u16,
+    ) -> StreamCompletion {
+        self.tasks_live.fetch_add(1, Ordering::AcqRel);
+        StreamCompletion {
+            session: Arc::clone(self),
+            stream,
+            peer_port,
+            retain_rejected: Arc::new(AtomicBool::new(false)),
+        }
+    }
+}
+
 impl Drop for StreamCompletion {
     fn drop(&mut self) {
         self.session.trace_lifecycle(
             crate::web::trace::TraceLifecycleEvent::StreamClosed,
-            Some(self.stream_id),
+            Some(self.stream.id),
             None,
         );
         if self.retain_rejected.load(Ordering::Acquire) {
             self.session
-                .stream_rejected_before_spawn(self.stream_id, self.peer_port, true);
+                .stream_rejected_before_spawn(self.stream, self.peer_port, true);
         } else {
-            self.session.stream_finished(self.stream_id, self.peer_port);
+            self.session.stream_finished(self.stream, self.peer_port);
         }
         if self.session.tasks_live.fetch_sub(1, Ordering::AcqRel) == 1 {
             self.session.tasks_done.notify_waiters();
@@ -174,7 +215,7 @@ impl Drop for StreamCompletion {
 
 async fn run_stream(
     session: Arc<WebSession>,
-    stream_id: u32,
+    stream_identity: StreamIdentity,
     stream: WebLogicalStream,
     deps: crate::proxy::authenticated::ClientRuntimeDeps,
     replay_checker: Arc<crate::stats::ReplayChecker>,
@@ -191,13 +232,27 @@ async fn run_stream(
     let peer = std::net::SocketAddr::new(session.client_ip, peer_port);
     deps.stats.increment_connects_all();
 
-    // A carrier may publish OPEN before the local MTProto socket writes its
-    // first byte. Session and stream quotas bound this idle phase without
-    // consuming the process-wide active-handshake budget.
-    if reader.read_exact(&mut handshake[..1]).await.is_err() {
+    // Silent OPEN ownership has a separate absolute deadline so it cannot
+    // consume stream and tuple quotas indefinitely before handshake admission.
+    let first_byte = tokio::time::timeout(
+        Duration::from_secs(session.timeouts.stream_first_byte_secs),
+        reader.read_exact(&mut handshake[..1]),
+    )
+    .await;
+    if first_byte.is_err() {
+        session.trace_lifecycle(
+            crate::web::trace::TraceLifecycleEvent::HandshakeTimeout,
+            Some(stream_identity.id),
+            Some("first_byte_timeout"),
+        );
+        deps.stats
+            .increment_connects_bad_with_class("web_mtproto_first_byte_timeout");
+        return;
+    }
+    if first_byte.is_ok_and(|result| result.is_err()) {
         session.trace_lifecycle(
             crate::web::trace::TraceLifecycleEvent::HandshakeIo,
-            Some(stream_id),
+            Some(stream_identity.id),
             Some("first_byte_io"),
         );
         deps.stats
@@ -206,7 +261,7 @@ async fn run_stream(
     }
     session.trace_lifecycle(
         crate::web::trace::TraceLifecycleEvent::StreamFirstByte,
-        Some(stream_id),
+        Some(stream_identity.id),
         None,
     );
     let Some(manager) = session.manager.upgrade() else {
@@ -215,7 +270,7 @@ async fn run_stream(
     let Some(handshake_permit) = manager.try_stream_handshake() else {
         session.trace_lifecycle(
             crate::web::trace::TraceLifecycleEvent::StreamRejected,
-            Some(stream_id),
+            Some(stream_identity.id),
             Some("handshake_limit"),
         );
         return;
@@ -246,7 +301,7 @@ async fn run_stream(
         Err(_) => {
             session.trace_lifecycle(
                 crate::web::trace::TraceLifecycleEvent::HandshakeTimeout,
-                Some(stream_id),
+                Some(stream_identity.id),
                 Some("timeout"),
             );
             deps.stats
@@ -258,7 +313,7 @@ async fn run_stream(
         Ok(Err(_)) => {
             session.trace_lifecycle(
                 crate::web::trace::TraceLifecycleEvent::HandshakeIo,
-                Some(stream_id),
+                Some(stream_identity.id),
                 Some("io"),
             );
             deps.stats
@@ -268,7 +323,7 @@ async fn run_stream(
         Ok(Ok(crate::error::HandshakeResult::Success((reader, writer, success)))) => {
             session.trace_lifecycle(
                 crate::web::trace::TraceLifecycleEvent::HandshakeSucceeded,
-                Some(stream_id),
+                Some(stream_identity.id),
                 None,
             );
             (reader, writer, success)
@@ -276,7 +331,7 @@ async fn run_stream(
         Ok(Ok(_)) => {
             session.trace_lifecycle(
                 crate::web::trace::TraceLifecycleEvent::HandshakeRejected,
-                Some(stream_id),
+                Some(stream_identity.id),
                 Some("bad_client"),
             );
             deps.stats
@@ -286,7 +341,7 @@ async fn run_stream(
     };
     session.trace_lifecycle(
         crate::web::trace::TraceLifecycleEvent::RelayStarted,
-        Some(stream_id),
+        Some(stream_identity.id),
         None,
     );
     let relay_result = run_authenticated(
@@ -301,7 +356,7 @@ async fn run_stream(
     .await;
     session.trace_lifecycle(
         crate::web::trace::TraceLifecycleEvent::RelayEnded,
-        Some(stream_id),
+        Some(stream_identity.id),
         Some(if relay_result.is_ok() {
             "completed"
         } else {

src/web/session/backend_tests.rs

@@ -70,6 +70,10 @@ fn test_runtime_with_dc(
         user: "default".to_string(),
         secret_mode: WebSecretMode::Plain,
         carrier,
+        carrier_negotiation_enabled: false,
+        carrier_learning: true,
+        carriers: Arc::from([carrier]),
+        carrier_negotiation_deadlines_secs: [3, 5, 8, 12],
         capability: [7; 32],
         key_fingerprint: "0000000000000000".to_string(),
         max_sessions: 4,
@@ -120,6 +124,13 @@ fn test_runtime_with_dc(
         1,
         profile,
         [7; 32],
+        carrier,
+        1,
+        [9; 32],
+        None,
+        crate::web::manager::CarrierClientClass::Legacy,
+        None,
+        false,
         limits,
         timeouts,
     );
@@ -323,10 +334,11 @@ async fn silent_streams_do_not_consume_active_handshake_capacity() {
     assert_eq!(runtime.process_frame(2, 4, FrameType::Data, &[2]), Ok(4));
     settle_tasks().await;
 
+    {
         let state = runtime.session.state.lock();
         assert!(state.streams.contains_key(&1));
         assert!(!state.streams.contains_key(&2));
-    drop(state);
+    }
     runtime.shutdown().await;
 }
 
@@ -361,3 +373,17 @@ async fn cancellation_while_waiting_for_data_releases_stream_ownership() {
     );
     runtime.shutdown().await;
 }
+
+#[tokio::test]
+async fn exhausted_stream_identity_does_not_acquire_synthetic_port_ownership() {
+    let runtime = test_runtime(WebCarrier::Https, 1);
+    runtime.session.state.lock().next_stream_instance = u64::MAX;
+
+    assert_eq!(
+        runtime.process_frame(1, 1, FrameType::Open, &[]),
+        Err(ManagerError::Closed)
+    );
+    assert!(runtime.session.state.lock().active_peer_ports.is_empty());
+
+    runtime.shutdown().await;
+}

src/web/session/downlink.rs

@@ -1,7 +1,9 @@
+use std::sync::Arc;
 use std::time::{Duration, Instant};
 
 use bytes::{BufMut, Bytes, BytesMut};
 
+use super::resident::{OwnedBatchBody, PendingCounts, PendingResponseLease};
 use super::{
     DownBatch, PendingClass, PollResult, QUEUE_ITEM_COST, QueuedFrame, SessionState, WebSession,
 };
@@ -14,7 +16,7 @@ impl WebSession {
         if !self.carrier().is_multiplexed() {
             return Err(ManagerError::Protocol);
         }
-        let epoch = {
+        let (epoch, healthy) = {
             let mut state = self.state.lock();
             if state.closed {
                 return Err(ManagerError::Closed);
@@ -33,15 +35,29 @@ impl WebSession {
                     self.close();
                     return Err(ManagerError::Protocol);
                 }
+                let carrier_health_eligible = unacked.carrier_health_eligible;
                 self.release_unacked_locked(&mut state);
+                state.carrier_health_downlink |= carrier_health_eligible;
+                if carrier_health_eligible {
+                    state.carrier_health_activity_at = Some(Instant::now());
+                }
             } else if cursor != state.down_cursor {
                 drop(state);
                 self.close();
                 return Err(ManagerError::Protocol);
             }
-            state.down_epoch = state.down_epoch.wrapping_add(1).max(1);
-            state.down_epoch
+            let Some(epoch) = state.down_epoch.checked_add(1) else {
+                drop(state);
+                self.close();
+                return Err(ManagerError::Protocol);
             };
+            state.down_epoch = epoch;
+            let healthy = self.carrier_health_ready_locked(&mut state, Instant::now());
+            (state.down_epoch, healthy)
+        };
+        if healthy {
+            self.finish_carrier_health();
+        }
         self.down_notify.notify_waiters();
 
         let deadline = Duration::from_secs(self.timeouts.long_poll_secs);
@@ -60,6 +76,9 @@ impl WebSession {
                     if !state.pending_frames.is_empty() {
                         let batch = match self.take_down_batch_locked(&mut state, cursor) {
                             Ok(batch) => batch,
+                            Err(ManagerError::Backpressure) => {
+                                return Err(ManagerError::Backpressure);
+                            }
                             Err(error) => {
                                 drop(state);
                                 self.close();
@@ -121,6 +140,15 @@ impl WebSession {
             .limits
             .pending_items_per_session
             .saturating_sub(item_reserve);
+        let resident = self.resident.snapshot();
+        let pending_bytes = state.pending_bytes.saturating_add(resident.bytes());
+        let pending_items = state.pending_items.saturating_add(resident.items());
+        let pending_control_bytes = state
+            .pending_control_bytes
+            .saturating_add(resident.control_bytes);
+        let pending_control_items = state
+            .pending_control_items
+            .saturating_add(resident.control_items);
         if state.closed {
             return false;
         }
@@ -128,20 +156,14 @@ impl WebSession {
         let fits = if control {
             bytes <= self.limits.control_bytes_per_session
                 && items <= item_reserve
-                && state.pending_bytes
-                    <= self.limits.pending_bytes_per_session.saturating_sub(bytes)
-                && state.pending_items
-                    <= self.limits.pending_items_per_session.saturating_sub(items)
-                && state.pending_control_bytes
+                && pending_bytes <= self.limits.pending_bytes_per_session.saturating_sub(bytes)
+                && pending_items <= self.limits.pending_items_per_session.saturating_sub(items)
+                && pending_control_bytes
                     <= self.limits.control_bytes_per_session.saturating_sub(bytes)
-                && state.pending_control_items <= item_reserve.saturating_sub(items)
+                && pending_control_items <= item_reserve.saturating_sub(items)
         } else {
-            let data_bytes = state
-                .pending_bytes
-                .saturating_sub(state.pending_control_bytes);
-            let data_items = state
-                .pending_items
-                .saturating_sub(state.pending_control_items);
+            let data_bytes = pending_bytes.saturating_sub(pending_control_bytes);
+            let data_items = pending_items.saturating_sub(pending_control_items);
             let (byte_limit, item_limit) = if class == PendingClass::Downlink {
                 let uplink_bytes = self.limits.max_body_bytes.saturating_add(
                     self.limits
@@ -203,6 +225,21 @@ impl WebSession {
         }
     }
 
+    pub(super) fn release_local_locked(
+        &self,
+        state: &mut SessionState,
+        bytes: usize,
+        items: usize,
+        control: bool,
+    ) {
+        state.pending_bytes = state.pending_bytes.saturating_sub(bytes);
+        state.pending_items = state.pending_items.saturating_sub(items);
+        if control {
+            state.pending_control_bytes = state.pending_control_bytes.saturating_sub(bytes);
+            state.pending_control_items = state.pending_control_items.saturating_sub(items);
+        }
+    }
+
     /// Coalesces one flow-control update into the bounded control queue.
     pub(super) fn queue_window_locked(
         &self,
@@ -351,6 +388,12 @@ impl WebSession {
             body_len += queued.encoded.len();
             count += 1;
         }
+        let Some(manager) = self.manager.upgrade() else {
+            return Err(ManagerError::Closed);
+        };
+        let Some(_staging) = manager.try_downlink_staging_budget(body_len) else {
+            return Err(ManagerError::Backpressure);
+        };
         let mut body = BytesMut::with_capacity(body_len);
         let mut data_bytes = 0usize;
         let mut data_items = 0usize;
@@ -383,14 +426,25 @@ impl WebSession {
             *index = index.saturating_sub(count);
         }
         state.down_cursor = next_cursor;
+        let counts = PendingCounts {
+            data_bytes,
+            data_items,
+            control_bytes,
+            control_items,
+        };
+        let lease = PendingResponseLease::new(self, counts, None);
+        let body = Bytes::from_owner(OwnedBatchBody::new(body.freeze(), Arc::clone(&lease)));
         Ok(DownBatch {
-            body: body.freeze(),
+            body,
+            lease,
             base_cursor: cursor,
             next_cursor,
             data_bytes,
             data_items,
             control_bytes,
             control_items,
+            carrier_health_eligible: state.negotiation_phase
+                == super::SessionNegotiationPhase::Committed,
         })
     }
 
@@ -398,8 +452,9 @@ impl WebSession {
         let Some(batch) = state.unacked.take() else {
             return;
         };
-        self.release_locked(state, batch.data_bytes, batch.data_items, false);
-        self.release_locked(state, batch.control_bytes, batch.control_items, true);
+        batch.lease.detach();
+        self.release_local_locked(state, batch.data_bytes, batch.data_items, false);
+        self.release_local_locked(state, batch.control_bytes, batch.control_items, true);
         for stream in state.streams.values_mut() {
             if let Some(waker) = stream.write_waker.take() {
                 waker.wake();
@@ -409,106 +464,5 @@ impl WebSession {
 }
 
 #[cfg(test)]
-mod tests {
-    use super::*;
-    use std::net::SocketAddr;
-    use std::sync::Arc;
-
-    use crate::config::{
-        WebCarrier, WebLimitsConfig, WebRuntimeProfile, WebSecretMode, WebTimeoutsConfig,
-    };
-    use crate::web::manager::WebProcessRuntime;
-
-    fn session() -> Arc<WebSession> {
-        let profile = Arc::new(WebRuntimeProfile {
-            host: "proxy.example.com".to_string(),
-            public_addr: SocketAddr::from(([203, 0, 113, 10], 443)),
-            user: "alice".to_string(),
-            secret_mode: WebSecretMode::Plain,
-            carrier: WebCarrier::Https,
-            capability: [0; 32],
-            key_fingerprint: "0000000000000000".to_string(),
-            max_sessions: 1,
-            max_streams: 1,
-            max_streams_per_session: 1,
-        });
-        WebSession::new(
-            std::sync::Weak::<WebProcessRuntime>::new(),
-            [1; 32],
-            "192.0.2.10".parse().unwrap(),
-            1,
-            profile,
-            [2; 32],
-            WebLimitsConfig::default(),
-            WebTimeoutsConfig::default(),
-        )
-    }
-
-    fn queue_close(session: &WebSession) {
-        let encoded = frame::encode(FrameType::Close, 1, &[]);
-        session.state.lock().pending_frames.push_back(QueuedFrame {
-            encoded: BytesMut::from(encoded.as_ref()),
-            frame_type: FrameType::Close,
-            stream_id: 1,
-            control: true,
-            cost: frame::HEADER_BYTES + QUEUE_ITEM_COST,
-        });
-    }
-
-    #[tokio::test]
-    async fn downlink_replays_unacknowledged_batch_byte_for_byte() {
-        let session = session();
-        queue_close(&session);
-        let first = session.poll_down(0).await.unwrap();
-        let replay = session.poll_down(0).await.unwrap();
-        assert_eq!(first.next_cursor, 1);
-        assert_eq!(replay.next_cursor, 1);
-        assert_eq!(first.body, replay.body);
-    }
-
-    #[tokio::test]
-    async fn invalid_or_overflowing_cursor_closes_session() {
-        let invalid = session();
-        assert!(matches!(
-            invalid.poll_down(1).await,
-            Err(ManagerError::Protocol)
-        ));
-        assert!(invalid.state.lock().closed);
-
-        let overflow = session();
-        {
-            let mut state = overflow.state.lock();
-            state.down_cursor = u64::MAX;
-        }
-        queue_close(&overflow);
-        assert!(matches!(
-            overflow.poll_down(u64::MAX).await,
-            Err(ManagerError::Protocol)
-        ));
-        assert!(overflow.state.lock().closed);
-    }
-
-    #[tokio::test]
-    async fn newer_poll_supersedes_older_poll_without_closing_session() {
-        let session = session();
-        let first_session = Arc::clone(&session);
-        let first = tokio::spawn(async move { first_session.poll_down(0).await });
-        while session.state.lock().down_epoch < 1 {
-            tokio::task::yield_now().await;
-        }
-        let second_session = Arc::clone(&session);
-        let second = tokio::spawn(async move { second_session.poll_down(0).await });
-        while session.state.lock().down_epoch < 2 {
-            tokio::task::yield_now().await;
-        }
-        let superseded = tokio::time::timeout(Duration::from_secs(1), first)
-            .await
-            .unwrap()
-            .unwrap()
-            .unwrap();
-        assert!(superseded.body.is_empty());
-        assert_eq!(superseded.next_cursor, 0);
-        assert!(!session.state.lock().closed);
-        second.abort();
-    }
-}
+#[path = "downlink_tests.rs"]
+mod tests;

src/web/session/downlink_tests.rs

@@ -0,0 +1,142 @@
+use super::*;
+use std::net::SocketAddr;
+use std::sync::Arc;
+
+use arc_swap::ArcSwap;
+
+use crate::config::{
+    ProxyConfig, WebCarrier, WebLimitsConfig, WebRuntimeProfile, WebSecretMode, WebTimeoutsConfig,
+};
+use crate::maestro::generation::test_runtime_generation;
+use crate::web::manager::WebProcessRuntime;
+
+fn session() -> (Arc<WebSession>, Arc<WebProcessRuntime>) {
+    let generation = test_runtime_generation(1, ProxyConfig::default());
+    let manager = WebProcessRuntime::start(Arc::new(ArcSwap::from(generation)));
+    let profile = Arc::new(WebRuntimeProfile {
+        host: "proxy.example.com".to_string(),
+        public_addr: SocketAddr::from(([203, 0, 113, 10], 443)),
+        user: "alice".to_string(),
+        secret_mode: WebSecretMode::Plain,
+        carrier: WebCarrier::Https,
+        carrier_negotiation_enabled: false,
+        carrier_learning: false,
+        carriers: Arc::from([WebCarrier::Https]),
+        carrier_negotiation_deadlines_secs: [3, 5, 8, 12],
+        capability: [0; 32],
+        key_fingerprint: "0000000000000000".to_string(),
+        max_sessions: 1,
+        max_streams: 1,
+        max_streams_per_session: 1,
+    });
+    let mut timeouts = WebTimeoutsConfig::default();
+    timeouts.long_poll_secs = 1;
+    let session = WebSession::new(
+        Arc::downgrade(&manager),
+        [1; 32],
+        "192.0.2.10".parse().unwrap(),
+        1,
+        profile,
+        [2; 32],
+        WebCarrier::Https,
+        1,
+        [3; 32],
+        None,
+        crate::web::manager::CarrierClientClass::Legacy,
+        None,
+        false,
+        WebLimitsConfig::default(),
+        timeouts,
+    );
+    (session, manager)
+}
+
+fn queue_close(session: &WebSession) {
+    let mut state = session.state.lock();
+    assert!(session.queue_control_locked(&mut state, FrameType::Close, 1, &[]));
+}
+
+#[tokio::test]
+async fn downlink_replays_unacknowledged_batch_byte_for_byte() {
+    let (session, manager) = session();
+    queue_close(&session);
+    let first = session.poll_down(0).await.unwrap();
+    let replay = session.poll_down(0).await.unwrap();
+    assert_eq!(first.next_cursor, 1);
+    assert_eq!(replay.next_cursor, 1);
+    assert_eq!(first.body, replay.body);
+    drop(first);
+    drop(replay);
+    session.close();
+    manager.shutdown().await;
+}
+
+#[tokio::test]
+async fn acknowledged_response_stays_resident_until_the_last_body_clone_drops() {
+    let (session, manager) = session();
+    queue_close(&session);
+    let response = session.poll_down(0).await.unwrap();
+    let retained = response.body.clone();
+    {
+        let mut state = session.state.lock();
+        session.release_unacked_locked(&mut state);
+        assert_eq!(state.pending_bytes, 0);
+    }
+    assert!(session.resident.snapshot().bytes() > 0);
+    drop(response);
+    assert!(session.resident.snapshot().bytes() > 0);
+    drop(retained);
+    assert_eq!(session.resident.snapshot().bytes(), 0);
+    session.close();
+    manager.shutdown().await;
+}
+
+#[tokio::test]
+async fn invalid_or_overflowing_cursor_closes_session() {
+    let (invalid, invalid_manager) = session();
+    assert!(matches!(
+        invalid.poll_down(1).await,
+        Err(ManagerError::Protocol)
+    ));
+    assert!(invalid.state.lock().closed);
+    invalid_manager.shutdown().await;
+
+    let (overflow, overflow_manager) = session();
+    {
+        let mut state = overflow.state.lock();
+        state.down_cursor = u64::MAX;
+    }
+    queue_close(&overflow);
+    assert!(matches!(
+        overflow.poll_down(u64::MAX).await,
+        Err(ManagerError::Protocol)
+    ));
+    assert!(overflow.state.lock().closed);
+    overflow_manager.shutdown().await;
+}
+
+#[tokio::test]
+async fn newer_poll_supersedes_older_poll_without_closing_session() {
+    let (session, manager) = session();
+    let first_session = Arc::clone(&session);
+    let first = tokio::spawn(async move { first_session.poll_down(0).await });
+    while session.state.lock().down_epoch < 1 {
+        tokio::task::yield_now().await;
+    }
+    let second_session = Arc::clone(&session);
+    let second = tokio::spawn(async move { second_session.poll_down(0).await });
+    while session.state.lock().down_epoch < 2 {
+        tokio::task::yield_now().await;
+    }
+    let superseded = tokio::time::timeout(Duration::from_secs(1), first)
+        .await
+        .unwrap()
+        .unwrap()
+        .unwrap();
+    assert!(superseded.body.is_empty());
+    assert_eq!(superseded.next_cursor, 0);
+    assert!(!session.state.lock().closed);
+    second.abort();
+    session.close();
+    manager.shutdown().await;
+}

src/web/session/lane_downlink.rs

@@ -0,0 +1,92 @@
+use std::sync::Arc;
+
+use bytes::{Bytes, BytesMut};
+
+use super::resident::{OwnedBatchBody, PendingCounts, PendingResponseLease};
+use super::{CarrierLane, DownBatch, WebSession};
+use crate::config::WebLimitsConfig;
+use crate::web::frame::FrameType;
+use crate::web::manager::ManagerError;
+
+/// Stages one bounded lane batch and transfers its accounting into response ownership.
+pub(super) fn take_lane_down_batch(
+    session: &WebSession,
+    limits: &WebLimitsConfig,
+    lane: &mut CarrierLane,
+    cursor: u64,
+    carrier_health_eligible: bool,
+) -> Result<DownBatch, ManagerError> {
+    let next_cursor = lane
+        .down_cursor
+        .checked_add(1)
+        .ok_or(ManagerError::Protocol)?;
+    let mut count = 0usize;
+    let mut body_len = 0usize;
+    for queued in &lane.pending_frames {
+        if count >= limits.max_frames_per_body
+            || (count != 0
+                && body_len.saturating_add(queued.encoded.len()) > limits.carrier_batch_bytes)
+        {
+            break;
+        }
+        body_len += queued.encoded.len();
+        count += 1;
+    }
+    let Some(manager) = session.manager.upgrade() else {
+        return Err(ManagerError::Closed);
+    };
+    let Some(_staging) = manager.try_downlink_staging_budget(body_len) else {
+        return Err(ManagerError::Backpressure);
+    };
+    let mut body = BytesMut::with_capacity(body_len);
+    let mut data_bytes = 0usize;
+    let mut data_items = 0usize;
+    let mut control_bytes = 0usize;
+    let mut control_items = 0usize;
+    for index in 0..count {
+        let Some(queued) = lane.pending_frames.get(index) else {
+            break;
+        };
+        if queued.frame_type == FrameType::Window
+            && lane.pending_windows.get(&queued.stream_id) == Some(&index)
+        {
+            lane.pending_windows.remove(&queued.stream_id);
+        }
+    }
+    for _ in 0..count {
+        let Some(queued) = lane.pending_frames.pop_front() else {
+            break;
+        };
+        body.extend_from_slice(&queued.encoded);
+        if queued.control {
+            control_bytes += queued.cost;
+            control_items += 1;
+        } else {
+            data_bytes += queued.cost;
+            data_items += 1;
+        }
+    }
+    for index in lane.pending_windows.values_mut() {
+        *index = index.saturating_sub(count);
+    }
+    lane.down_cursor = next_cursor;
+    let counts = PendingCounts {
+        data_bytes,
+        data_items,
+        control_bytes,
+        control_items,
+    };
+    let lease = PendingResponseLease::new(session, counts, Some(Arc::clone(&lane.resident)));
+    let body = Bytes::from_owner(OwnedBatchBody::new(body.freeze(), Arc::clone(&lease)));
+    Ok(DownBatch {
+        body,
+        lease,
+        base_cursor: cursor,
+        next_cursor,
+        data_bytes,
+        data_items,
+        control_bytes,
+        control_items,
+        carrier_health_eligible,
+    })
+}

src/web/session/lane_uplink.rs

@@ -0,0 +1,196 @@
+use std::sync::Arc;
+use std::time::Instant;
+
+use sha2::{Digest, Sha256};
+use subtle::ConstantTimeEq;
+
+use super::uplink::{AppliedProgress, inbound_reservation, validate_batch};
+use super::{PendingClass, WebSession, insert_carrier_lane};
+use crate::config::WebCarrier;
+use crate::web::frame::{self, Frame, FrameType};
+use crate::web::manager::{ManagerError, TokenHash};
+
+impl WebSession {
+    /// Applies one exactly-once uplink batch to an independent HTTPS lane.
+    pub(crate) fn process_up_lane(
+        self: &Arc<Self>,
+        lane_id: u32,
+        sequence: u64,
+        body: &[u8],
+    ) -> Result<u64, ManagerError> {
+        if self.carrier() != WebCarrier::HttpsLanes || lane_id > frame::MAX_STREAM_ID {
+            return Err(ManagerError::Protocol);
+        }
+        let frames = match frame::parse_all(body, &self.limits) {
+            Ok(frames) => frames,
+            Err(_) => {
+                self.close();
+                return Err(ManagerError::Protocol);
+            }
+        };
+        if frames
+            .iter()
+            .copied()
+            .any(|value| value.stream_id != lane_id || frame::validate_client_shape(value).is_err())
+        {
+            self.close();
+            return Err(ManagerError::Protocol);
+        }
+        let digest: TokenHash = Sha256::digest(body).into();
+        let mut opened = Vec::new();
+        let mut committed = false;
+        let mut healthy = false;
+        let result = {
+            let mut state = self.state.lock();
+            if state.closed {
+                return Err(ManagerError::Closed);
+            }
+            self.ensure_carrier_active_locked(&state)?;
+            state.last_activity = Instant::now();
+            let new_lane = !state.carrier_lanes.contains_key(&lane_id);
+            if new_lane {
+                if lane_id != 0
+                    && frames
+                        .first()
+                        .is_some_and(|value| value.frame_type != FrameType::Open)
+                    && only_late_frames(&frames)
+                {
+                    return if self.automatic_carrier
+                        && state.negotiation_phase != super::SessionNegotiationPhase::Committed
+                    {
+                        Err(ManagerError::Backpressure)
+                    } else {
+                        Ok(sequence)
+                    };
+                }
+                if lane_id == 0
+                    || frames
+                        .first()
+                        .is_none_or(|value| value.frame_type != FrameType::Open)
+                {
+                    drop(state);
+                    self.close();
+                    return Err(ManagerError::Protocol);
+                }
+                let lane_limit = self
+                    .profile
+                    .max_streams_per_session
+                    .saturating_add(self.limits.max_tombstones_per_session)
+                    .saturating_add(1);
+                if state.carrier_lanes.len() >= lane_limit {
+                    return Err(ManagerError::Limit);
+                }
+            }
+            let (last_sequence, last_digest, up_active) = state
+                .carrier_lanes
+                .get(&lane_id)
+                .map_or((0, [0; 32], false), |lane| {
+                    (lane.last_up_sequence, lane.last_up_digest, lane.up_active)
+                });
+            if sequence == last_sequence && sequence != 0 {
+                return if bool::from(last_digest.ct_eq(&digest)) {
+                    Ok(sequence)
+                } else {
+                    drop(state);
+                    self.close();
+                    Err(ManagerError::Protocol)
+                };
+            }
+            if sequence == 0 || sequence != last_sequence.saturating_add(1) {
+                drop(state);
+                self.close();
+                return Err(ManagerError::Protocol);
+            }
+            if up_active {
+                return Err(ManagerError::Concurrent);
+            }
+            if !validate_batch(&state, &frames) {
+                drop(state);
+                self.close();
+                return Err(ManagerError::Protocol);
+            }
+            let (reserve_bytes, reserve_items) = inbound_reservation(&state, &frames);
+            if !self.reserve_locked(
+                &mut state,
+                reserve_bytes,
+                reserve_items,
+                PendingClass::Uplink,
+            ) {
+                if let Some(lane) = state.carrier_lanes.get_mut(&lane_id) {
+                    lane.up_active = false;
+                }
+                return Err(ManagerError::Backpressure);
+            }
+            if new_lane && insert_carrier_lane(&mut state, lane_id).is_none() {
+                self.release_locked(&mut state, reserve_bytes, reserve_items, false);
+                drop(state);
+                self.close();
+                return Err(ManagerError::Protocol);
+            }
+            let Some(lane) = state.carrier_lanes.get_mut(&lane_id) else {
+                self.release_locked(&mut state, reserve_bytes, reserve_items, false);
+                return Err(ManagerError::Closed);
+            };
+            lane.up_active = true;
+            let mut unused_bytes = reserve_bytes;
+            let mut unused_items = reserve_items;
+            let mut progress = AppliedProgress::default();
+            let applied = self.apply_batch_locked(
+                &mut state,
+                &frames,
+                &mut opened,
+                &mut None,
+                &mut unused_bytes,
+                &mut unused_items,
+                &mut progress,
+            );
+            self.release_locked(&mut state, unused_bytes, unused_items, false);
+            if let Some(lane) = state.carrier_lanes.get_mut(&lane_id) {
+                lane.up_active = false;
+                if applied {
+                    lane.last_up_sequence = sequence;
+                    lane.last_up_digest = digest;
+                }
+            }
+            if applied {
+                (committed, healthy) = self.record_uplink_progress_locked(&mut state, progress);
+            }
+            applied.then_some(sequence).ok_or(ManagerError::Closed)
+        };
+        if matches!(result, Err(ManagerError::Backpressure)) {
+            return result;
+        }
+        if result.is_err() {
+            self.close();
+            drop(opened);
+            return result;
+        }
+        if self.automatic_carrier && !self.is_carrier_committed() {
+            self.lane_open_notify.notify_waiters();
+            return Err(ManagerError::Backpressure);
+        }
+        if committed {
+            self.finish_carrier_commit();
+        }
+        if healthy {
+            self.finish_carrier_health();
+        }
+        self.lane_open_notify.notify_waiters();
+        for completion in opened {
+            self.spawn_stream(completion, false);
+        }
+        if let Some(manager) = self.manager.upgrade() {
+            manager.record_up(body.len());
+        }
+        result
+    }
+}
+
+fn only_late_frames(frames: &[Frame<'_>]) -> bool {
+    frames.iter().all(|value| {
+        matches!(
+            value.frame_type,
+            FrameType::Data | FrameType::Window | FrameType::Close
+        )
+    })
+}

src/web/session/lanes.rs

@@ -2,150 +2,17 @@ use std::sync::Arc;
 use std::time::{Duration, Instant};
 
 use bytes::{BufMut, Bytes, BytesMut};
-use sha2::{Digest, Sha256};
-use subtle::ConstantTimeEq;
+use tokio::sync::OwnedSemaphorePermit;
 
-use super::uplink::{inbound_reservation, validate_batch};
+use super::lane_downlink::take_lane_down_batch;
 use super::{
-    CarrierLane, DownBatch, PendingClass, PollResult, QUEUE_ITEM_COST, QueuedFrame, SessionState,
-    WebSession, remember_closed,
+    PendingClass, PollResult, QUEUE_ITEM_COST, QueuedFrame, SessionState, WebSession,
+    remember_closed,
 };
-use crate::config::{WebCarrier, WebLimitsConfig};
-use crate::web::frame::{self, Frame, FrameType};
-use crate::web::manager::{ManagerError, TokenHash};
+use crate::web::frame::{self, FrameType};
+use crate::web::manager::ManagerError;
 
 impl WebSession {
-    /// Applies one exactly-once uplink batch to an independent HTTPS lane.
-    pub(crate) fn process_up_lane(
-        self: &Arc<Self>,
-        lane_id: u32,
-        sequence: u64,
-        body: &[u8],
-    ) -> Result<u64, ManagerError> {
-        if self.carrier() != WebCarrier::HttpsLanes || lane_id > frame::MAX_STREAM_ID {
-            return Err(ManagerError::Protocol);
-        }
-        let frames = match frame::parse_all(body, &self.limits) {
-            Ok(frames) => frames,
-            Err(_) => {
-                self.close();
-                return Err(ManagerError::Protocol);
-            }
-        };
-        if frames
-            .iter()
-            .copied()
-            .any(|value| value.stream_id != lane_id || frame::validate_client_shape(value).is_err())
-        {
-            self.close();
-            return Err(ManagerError::Protocol);
-        }
-        let digest: TokenHash = Sha256::digest(body).into();
-        let mut opened = Vec::new();
-        let result = {
-            let mut state = self.state.lock();
-            if state.closed {
-                return Err(ManagerError::Closed);
-            }
-            state.last_activity = Instant::now();
-            if !state.carrier_lanes.contains_key(&lane_id) {
-                if lane_id != 0
-                    && frames
-                        .first()
-                        .is_some_and(|value| value.frame_type != FrameType::Open)
-                    && only_late_frames(&frames)
-                {
-                    return Ok(sequence);
-                }
-                if lane_id == 0
-                    || frames
-                        .first()
-                        .is_none_or(|value| value.frame_type != FrameType::Open)
-                {
-                    drop(state);
-                    self.close();
-                    return Err(ManagerError::Protocol);
-                }
-                state.carrier_lanes.insert(lane_id, CarrierLane::new());
-            }
-            let lane = state
-                .carrier_lanes
-                .get_mut(&lane_id)
-                .ok_or(ManagerError::Protocol)?;
-            if sequence == lane.last_up_sequence && sequence != 0 {
-                return if bool::from(lane.last_up_digest.ct_eq(&digest)) {
-                    Ok(sequence)
-                } else {
-                    drop(state);
-                    self.close();
-                    Err(ManagerError::Protocol)
-                };
-            }
-            if sequence == 0 || sequence != lane.last_up_sequence.saturating_add(1) {
-                drop(state);
-                self.close();
-                return Err(ManagerError::Protocol);
-            }
-            if lane.up_active {
-                return Err(ManagerError::Concurrent);
-            }
-            lane.up_active = true;
-            if !validate_batch(&state, &frames) {
-                drop(state);
-                self.close();
-                return Err(ManagerError::Protocol);
-            }
-            let (reserve_bytes, reserve_items) = inbound_reservation(&state, &frames);
-            if !self.reserve_locked(
-                &mut state,
-                reserve_bytes,
-                reserve_items,
-                PendingClass::Uplink,
-            ) {
-                if let Some(lane) = state.carrier_lanes.get_mut(&lane_id) {
-                    lane.up_active = false;
-                }
-                return Err(ManagerError::Backpressure);
-            }
-            let mut unused_bytes = reserve_bytes;
-            let mut unused_items = reserve_items;
-            let applied = self.apply_batch_locked(
-                &mut state,
-                &frames,
-                &mut opened,
-                &mut None,
-                &mut unused_bytes,
-                &mut unused_items,
-            );
-            self.release_locked(&mut state, unused_bytes, unused_items, false);
-            if let Some(lane) = state.carrier_lanes.get_mut(&lane_id) {
-                lane.up_active = false;
-                if applied {
-                    lane.last_up_sequence = sequence;
-                    lane.last_up_digest = digest;
-                }
-            }
-            applied.then_some(sequence).ok_or(ManagerError::Closed)
-        };
-        if matches!(result, Err(ManagerError::Backpressure)) {
-            return result;
-        }
-        if result.is_err() {
-            self.close();
-            for (_, peer_port) in opened {
-                self.release_stream_reservation(peer_port);
-            }
-            return result;
-        }
-        for (stream_id, peer_port) in opened {
-            self.spawn_stream(stream_id, peer_port, false);
-        }
-        if let Some(manager) = self.manager.upgrade() {
-            manager.record_up(body.len());
-        }
-        result
-    }
-
     /// Polls one lane with independent cursor replay and newest-poll-wins semantics.
     pub(crate) async fn poll_down_lane(
         &self,
@@ -155,14 +22,26 @@ impl WebSession {
         if !self.carrier().uses_lanes() || lane_id > frame::MAX_STREAM_ID {
             return Err(ManagerError::Protocol);
         }
-        let (epoch, notify) = {
+        if !self.wait_for_lane_open(lane_id, cursor).await? {
+            return Ok(PollResult {
+                body: Bytes::new(),
+                next_cursor: cursor,
+                lane_closed: false,
+            });
+        }
+        let (instance, epoch, notify, healthy) = {
             let mut state = self.state.lock();
             if state.closed {
                 return Err(ManagerError::Closed);
             }
+            state.last_activity = Instant::now();
             let acknowledged = {
                 let Some(lane) = state.carrier_lanes.get_mut(&lane_id) else {
-                    return Err(ManagerError::Protocol);
+                    return Ok(PollResult {
+                        body: Bytes::new(),
+                        next_cursor: cursor,
+                        lane_closed: true,
+                    });
                 };
                 if let Some(unacked) = &lane.unacked {
                     if cursor == unacked.base_cursor {
@@ -188,22 +67,46 @@ impl WebSession {
                 }
             };
             if let Some(batch) = acknowledged {
-                self.release_locked(&mut state, batch.data_bytes, batch.data_items, false);
-                self.release_locked(&mut state, batch.control_bytes, batch.control_items, true);
+                if let Some(lane) = state.carrier_lanes.get_mut(&lane_id) {
+                    lane.pending_bytes = lane.pending_bytes.saturating_sub(batch.data_bytes);
+                    lane.pending_items = lane.pending_items.saturating_sub(batch.data_items);
+                }
+                batch.lease.detach();
+                self.release_local_locked(&mut state, batch.data_bytes, batch.data_items, false);
+                self.release_local_locked(
+                    &mut state,
+                    batch.control_bytes,
+                    batch.control_items,
+                    true,
+                );
+                state.carrier_health_downlink |= batch.carrier_health_eligible;
+                if batch.carrier_health_eligible {
+                    state.carrier_health_activity_at = Some(Instant::now());
+                }
                 if let Some(stream) = state.streams.get_mut(&lane_id)
                     && let Some(waker) = stream.write_waker.take()
                 {
                     waker.wake();
                 }
             }
-            state.last_activity = Instant::now();
             let lane = state
                 .carrier_lanes
                 .get_mut(&lane_id)
                 .ok_or(ManagerError::Protocol)?;
-            lane.down_epoch = lane.down_epoch.wrapping_add(1).max(1);
-            (lane.down_epoch, Arc::clone(&lane.notify))
+            let Some(epoch) = lane.down_epoch.checked_add(1) else {
+                drop(state);
+                self.close();
+                return Err(ManagerError::Protocol);
             };
+            lane.down_epoch = epoch;
+            let instance = lane.instance;
+            let notify = Arc::clone(&lane.notify);
+            let healthy = self.carrier_health_ready_locked(&mut state, Instant::now());
+            (instance, epoch, notify, healthy)
+        };
+        if healthy {
+            self.finish_carrier_health();
+        }
         notify.notify_waiters();
 
         let deadline = Duration::from_secs(self.timeouts.long_poll_secs);
@@ -215,6 +118,8 @@ impl WebSession {
                     if state.closed {
                         return Err(ManagerError::Closed);
                     }
+                    let carrier_health_eligible = lane_id != 0
+                        && state.negotiation_phase == super::SessionNegotiationPhase::Committed;
                     let Some(lane) = state.carrier_lanes.get_mut(&lane_id) else {
                         return Ok(PollResult {
                             body: Bytes::new(),
@@ -222,6 +127,13 @@ impl WebSession {
                             lane_closed: true,
                         });
                     };
+                    if lane.instance != instance {
+                        return Ok(PollResult {
+                            body: Bytes::new(),
+                            next_cursor: cursor,
+                            lane_closed: true,
+                        });
+                    }
                     if lane.down_epoch != epoch {
                         return Ok(PollResult {
                             body: Bytes::new(),
@@ -230,8 +142,17 @@ impl WebSession {
                         });
                     }
                     if !lane.pending_frames.is_empty() {
-                        let batch = match take_lane_down_batch(&self.limits, lane, cursor) {
+                        let batch = match take_lane_down_batch(
+                            self,
+                            &self.limits,
+                            lane,
+                            cursor,
+                            carrier_health_eligible,
+                        ) {
                             Ok(batch) => batch,
+                            Err(ManagerError::Backpressure) => {
+                                return Err(ManagerError::Backpressure);
+                            }
                             Err(error) => {
                                 drop(state);
                                 self.close();
@@ -288,13 +209,18 @@ impl WebSession {
                         lane_closed: true,
                     });
                 }
-                if state
-                    .carrier_lanes
-                    .get(&lane_id)
-                    .is_some_and(|lane| lane.down_epoch == epoch)
-                {
+                if let Some(lane) = state.carrier_lanes.get(&lane_id) {
+                    if lane.instance != instance {
+                        return Ok(PollResult {
+                            body: Bytes::new(),
+                            next_cursor: cursor,
+                            lane_closed: true,
+                        });
+                    }
+                    if lane.down_epoch == epoch {
                         state.last_activity = Instant::now();
                     }
+                }
                 Ok(PollResult {
                     body: Bytes::new(),
                     next_cursor: cursor,
@@ -304,6 +230,76 @@ impl WebSession {
         }
     }
 
+    async fn wait_for_lane_open(&self, lane_id: u32, cursor: u64) -> Result<bool, ManagerError> {
+        let wait = {
+            let mut state = self.state.lock();
+            if state.closed {
+                return Err(ManagerError::Closed);
+            }
+            if state.carrier_lanes.contains_key(&lane_id) {
+                return Ok(true);
+            }
+            if cursor != 0 || lane_id == 0 {
+                drop(state);
+                self.close();
+                return Err(ManagerError::Protocol);
+            }
+            if state.closed_streams.contains(&lane_id)
+                || state.closing_streams.contains_key(&lane_id)
+            {
+                return Ok(true);
+            }
+            if state.lane_open_waits >= self.limits.max_lane_open_waits_per_session {
+                return Err(ManagerError::Limit);
+            }
+            let Some(manager) = self.manager.upgrade() else {
+                return Err(ManagerError::Closed);
+            };
+            let Some(auxiliary) = manager.try_lane_poll(true) else {
+                return Err(ManagerError::Limit);
+            };
+            state.lane_open_waits += 1;
+            LaneOpenWaitGuard {
+                session: self,
+                _auxiliary: auxiliary,
+            }
+        };
+        let deadline = Duration::from_secs(self.timeouts.lane_open_wait_secs);
+        let opened = tokio::time::timeout(deadline, async {
+            loop {
+                let notified = self.lane_open_notify.notified();
+                {
+                    let state = self.state.lock();
+                    if state.closed {
+                        return Err(ManagerError::Closed);
+                    }
+                    if state.carrier_lanes.contains_key(&lane_id)
+                        || state.closed_streams.contains(&lane_id)
+                        || state.closing_streams.contains_key(&lane_id)
+                    {
+                        return Ok(true);
+                    }
+                }
+                notified.await;
+            }
+        })
+        .await;
+        drop(wait);
+        match opened {
+            Ok(result) => result,
+            Err(_) => {
+                let state = self.state.lock();
+                if state.closed {
+                    Err(ManagerError::Closed)
+                } else {
+                    Ok(state.carrier_lanes.contains_key(&lane_id)
+                        || state.closed_streams.contains(&lane_id)
+                        || state.closing_streams.contains_key(&lane_id))
+                }
+            }
+        }
+    }
+
     pub(super) fn queue_lane_frame_locked(
         &self,
         state: &mut SessionState,
@@ -350,6 +346,17 @@ impl WebSession {
                             <= self.limits.max_frame_payload_bytes
                 });
         if can_coalesce {
+            if state.carrier_lanes.get(&stream_id).is_none_or(|lane| {
+                let resident = lane.resident.snapshot();
+                payload.len() > self.limits.pending_bytes_per_lane
+                    || lane.pending_bytes.saturating_add(resident.data_bytes)
+                        > self
+                            .limits
+                            .pending_bytes_per_lane
+                            .saturating_sub(payload.len())
+            }) {
+                return false;
+            }
             if !self.reserve_locked(state, payload.len(), 0, PendingClass::Downlink) {
                 return false;
             }
@@ -365,6 +372,7 @@ impl WebSession {
             last.cost += payload.len();
             let payload_len = (last.encoded.len() - frame::HEADER_BYTES) as u32;
             last.encoded[4..8].copy_from_slice(&payload_len.to_be_bytes());
+            lane.pending_bytes += payload.len();
             lane.notify.notify_waiters();
             return true;
         }
@@ -374,6 +382,18 @@ impl WebSession {
         } else {
             PendingClass::Downlink
         };
+        if !control
+            && state.carrier_lanes.get(&stream_id).is_none_or(|lane| {
+                let resident = lane.resident.snapshot();
+                cost > self.limits.pending_bytes_per_lane
+                    || lane.pending_bytes.saturating_add(resident.data_bytes)
+                        > self.limits.pending_bytes_per_lane.saturating_sub(cost)
+                    || lane.pending_items.saturating_add(resident.data_items)
+                        >= self.limits.pending_items_per_lane
+            })
+        {
+            return false;
+        }
         if !self.reserve_locked(state, cost, 1, class) {
             return false;
         }
@@ -396,6 +416,10 @@ impl WebSession {
             control,
             cost,
         });
+        if !control {
+            lane.pending_bytes += cost;
+            lane.pending_items += 1;
+        }
         if frame_type == FrameType::Window {
             lane.pending_windows.insert(stream_id, index);
         }
@@ -435,87 +459,26 @@ impl WebSession {
             }
         }
         if let Some(batch) = lane.unacked.take() {
-            data_bytes = data_bytes.saturating_add(batch.data_bytes);
-            data_items = data_items.saturating_add(batch.data_items);
-            control_bytes = control_bytes.saturating_add(batch.control_bytes);
-            control_items = control_items.saturating_add(batch.control_items);
+            batch.lease.detach();
+            self.release_local_locked(state, batch.data_bytes, batch.data_items, false);
+            self.release_local_locked(state, batch.control_bytes, batch.control_items, true);
         }
         self.release_locked(state, data_bytes, data_items, false);
         self.release_locked(state, control_bytes, control_items, true);
+        self.lane_open_notify.notify_waiters();
     }
 }
 
-fn only_late_frames(frames: &[Frame<'_>]) -> bool {
-    frames.iter().all(|value| {
-        matches!(
-            value.frame_type,
-            FrameType::Data | FrameType::Window | FrameType::Close
-        )
-    })
+struct LaneOpenWaitGuard<'a> {
+    session: &'a WebSession,
+    _auxiliary: OwnedSemaphorePermit,
 }
 
-fn take_lane_down_batch(
-    limits: &WebLimitsConfig,
-    lane: &mut CarrierLane,
-    cursor: u64,
-) -> Result<DownBatch, ManagerError> {
-    let next_cursor = lane
-        .down_cursor
-        .checked_add(1)
-        .ok_or(ManagerError::Protocol)?;
-    let mut count = 0usize;
-    let mut body_len = 0usize;
-    for queued in &lane.pending_frames {
-        if count >= limits.max_frames_per_body
-            || (count != 0
-                && body_len.saturating_add(queued.encoded.len()) > limits.carrier_batch_bytes)
-        {
-            break;
+impl Drop for LaneOpenWaitGuard<'_> {
+    fn drop(&mut self) {
+        let mut state = self.session.state.lock();
+        state.lane_open_waits = state.lane_open_waits.saturating_sub(1);
     }
-        body_len += queued.encoded.len();
-        count += 1;
-    }
-    let mut body = BytesMut::with_capacity(body_len);
-    let mut data_bytes = 0usize;
-    let mut data_items = 0usize;
-    let mut control_bytes = 0usize;
-    let mut control_items = 0usize;
-    for index in 0..count {
-        let Some(queued) = lane.pending_frames.get(index) else {
-            break;
-        };
-        if queued.frame_type == FrameType::Window
-            && lane.pending_windows.get(&queued.stream_id) == Some(&index)
-        {
-            lane.pending_windows.remove(&queued.stream_id);
-        }
-    }
-    for _ in 0..count {
-        let Some(queued) = lane.pending_frames.pop_front() else {
-            break;
-        };
-        body.extend_from_slice(&queued.encoded);
-        if queued.control {
-            control_bytes += queued.cost;
-            control_items += 1;
-        } else {
-            data_bytes += queued.cost;
-            data_items += 1;
-        }
-    }
-    for index in lane.pending_windows.values_mut() {
-        *index = index.saturating_sub(count);
-    }
-    lane.down_cursor = next_cursor;
-    Ok(DownBatch {
-        body: body.freeze(),
-        base_cursor: cursor,
-        next_cursor,
-        data_bytes,
-        data_items,
-        control_bytes,
-        control_items,
-    })
 }
 
 // Lane-specific protocol, replay, and lifecycle tests.

src/web/session/lanes/tests.rs

@@ -1,19 +1,43 @@
 use std::net::SocketAddr;
 use std::sync::Arc;
 
+use arc_swap::ArcSwap;
 use bytes::BytesMut;
 
 use super::*;
-use crate::config::{WebRuntimeProfile, WebSecretMode, WebTimeoutsConfig};
+use crate::config::{
+    ProxyConfig, WebCarrier, WebLimitsConfig, WebRuntimeProfile, WebSecretMode, WebTimeoutsConfig,
+};
+use crate::maestro::generation::test_runtime_generation;
 use crate::web::manager::WebProcessRuntime;
+use crate::web::session::{CarrierLane, insert_carrier_lane};
 
 fn session_with_limits(limits: WebLimitsConfig) -> Arc<WebSession> {
+    new_session(limits, std::sync::Weak::new())
+}
+
+fn new_session(
+    limits: WebLimitsConfig,
+    manager: std::sync::Weak<WebProcessRuntime>,
+) -> Arc<WebSession> {
+    new_session_with_automatic(limits, manager, false)
+}
+
+fn new_session_with_automatic(
+    limits: WebLimitsConfig,
+    manager: std::sync::Weak<WebProcessRuntime>,
+    automatic: bool,
+) -> Arc<WebSession> {
     let profile = Arc::new(WebRuntimeProfile {
         host: "proxy.example.com".to_string(),
         public_addr: SocketAddr::from(([203, 0, 113, 10], 443)),
         user: "alice".to_string(),
         secret_mode: WebSecretMode::Plain,
         carrier: WebCarrier::HttpsLanes,
+        carrier_negotiation_enabled: false,
+        carrier_learning: true,
+        carriers: Arc::from([WebCarrier::HttpsLanes]),
+        carrier_negotiation_deadlines_secs: [3, 5, 8, 12],
         capability: [0; 32],
         key_fingerprint: "0000000000000000".to_string(),
         max_sessions: 1,
@@ -21,28 +45,150 @@ fn session_with_limits(limits: WebLimitsConfig) -> Arc<WebSession> {
         max_streams_per_session: 2,
     });
     WebSession::new(
-        std::sync::Weak::<WebProcessRuntime>::new(),
+        manager,
         [1; 32],
         "192.0.2.10".parse().unwrap(),
         1,
         profile,
         [2; 32],
+        WebCarrier::HttpsLanes,
+        1,
+        [3; 32],
+        None,
+        if automatic {
+            crate::web::manager::CarrierClientClass::Bridge
+        } else {
+            crate::web::manager::CarrierClientClass::Legacy
+        },
+        None,
+        automatic,
         limits,
         WebTimeoutsConfig::default(),
     )
 }
 
+fn session_with_manager() -> (Arc<WebSession>, Arc<WebProcessRuntime>) {
+    session_with_manager_limits(WebLimitsConfig::default())
+}
+
+fn session_with_manager_limits(
+    limits: WebLimitsConfig,
+) -> (Arc<WebSession>, Arc<WebProcessRuntime>) {
+    let generation = test_runtime_generation(1, ProxyConfig::default());
+    let manager = WebProcessRuntime::start(Arc::new(ArcSwap::from(generation)));
+    let session = new_session(limits, Arc::downgrade(&manager));
+    (session, manager)
+}
+
 fn session() -> Arc<WebSession> {
     session_with_limits(WebLimitsConfig::default())
 }
 
+#[tokio::test]
+async fn early_down_waits_without_creating_a_provisional_lane() {
+    let (session, manager) = session_with_manager();
+    let polling = Arc::clone(&session);
+    let poll = tokio::spawn(async move { polling.poll_down_lane(7, 0).await });
+    while session.state.lock().lane_open_waits == 0 {
+        tokio::task::yield_now().await;
+    }
+    assert!(!session.state.lock().carrier_lanes.contains_key(&7));
+    {
+        let mut state = session.state.lock();
+        assert!(insert_carrier_lane(&mut state, 7).is_some());
+        state.closed_streams.insert(7);
+        assert!(session.queue_control_locked(&mut state, FrameType::Close, 7, &[]));
+    }
+    session.lane_open_notify.notify_waiters();
+    let result = tokio::time::timeout(Duration::from_secs(1), poll)
+        .await
+        .unwrap()
+        .unwrap()
+        .unwrap();
+    assert!(!result.body.is_empty());
+    assert_eq!(session.state.lock().lane_open_waits, 0);
+    drop(result);
+    session.close();
+    manager.shutdown().await;
+}
+
+#[tokio::test(start_paused = true)]
+async fn early_down_timeout_is_empty_and_releases_its_session_slot() {
+    let (session, manager) = session_with_manager();
+    let polling = Arc::clone(&session);
+    let poll = tokio::spawn(async move { polling.poll_down_lane(7, 0).await });
+    while session.state.lock().lane_open_waits == 0 {
+        tokio::task::yield_now().await;
+    }
+    tokio::time::advance(Duration::from_secs(3)).await;
+    let result = poll.await.unwrap().unwrap();
+    assert!(result.body.is_empty());
+    assert_eq!(result.next_cursor, 0);
+    assert!(!result.lane_closed);
+    assert_eq!(session.state.lock().lane_open_waits, 0);
+    session.close();
+    manager.shutdown().await;
+}
+
+#[tokio::test]
+async fn early_down_admission_is_bounded_and_cancellation_safe() {
+    let limits = WebLimitsConfig {
+        max_lane_open_waits_per_session: 2,
+        ..WebLimitsConfig::default()
+    };
+    let (session, manager) = session_with_manager_limits(limits);
+    let mut waits = Vec::new();
+    for lane_id in [7, 8] {
+        let polling = Arc::clone(&session);
+        waits.push(tokio::spawn(async move {
+            polling.poll_down_lane(lane_id, 0).await
+        }));
+    }
+    while session.state.lock().lane_open_waits < 2 {
+        tokio::task::yield_now().await;
+    }
+    assert!(matches!(
+        session.poll_down_lane(9, 0).await,
+        Err(ManagerError::Limit)
+    ));
+    for wait in waits {
+        wait.abort();
+        let _ = wait.await;
+    }
+    assert_eq!(session.state.lock().lane_open_waits, 0);
+    session.close();
+    manager.shutdown().await;
+}
+
+#[tokio::test]
+async fn session_close_wakes_early_down_with_closed_state() {
+    let (session, manager) = session_with_manager();
+    let polling = Arc::clone(&session);
+    let poll = tokio::spawn(async move { polling.poll_down_lane(7, 0).await });
+    while session.state.lock().lane_open_waits == 0 {
+        tokio::task::yield_now().await;
+    }
+    session.close();
+    assert!(matches!(
+        tokio::time::timeout(Duration::from_secs(1), poll)
+            .await
+            .unwrap()
+            .unwrap(),
+        Err(ManagerError::Closed)
+    ));
+    assert_eq!(session.state.lock().lane_open_waits, 0);
+    manager.shutdown().await;
+}
+
 #[test]
 fn lane_uplink_sequences_are_independent_and_exactly_once() {
     let session = session();
     {
         let mut state = session.state.lock();
         for lane_id in [51, 52] {
-            state.carrier_lanes.insert(lane_id, CarrierLane::new());
+            state
+                .carrier_lanes
+                .insert(lane_id, CarrierLane::new(u64::from(lane_id)));
             state.closed_streams.insert(lane_id);
         }
     }
@@ -67,20 +213,12 @@ fn cross_lane_frame_is_fatal_to_https_lane_session() {
 
 #[tokio::test]
 async fn drained_closed_lane_replays_then_signals_completion() {
-    let session = session();
+    let (session, manager) = session_with_manager();
     {
         let mut state = session.state.lock();
-        state.carrier_lanes.insert(7, CarrierLane::new());
+        state.carrier_lanes.insert(7, CarrierLane::new(7));
         state.closed_streams.insert(7);
-        let lane = state.carrier_lanes.get_mut(&7).unwrap();
-        let encoded = frame::encode(FrameType::Close, 7, &[]);
-        lane.pending_frames.push_back(QueuedFrame {
-            encoded: BytesMut::from(encoded.as_ref()),
-            frame_type: FrameType::Close,
-            stream_id: 7,
-            control: true,
-            cost: frame::HEADER_BYTES + QUEUE_ITEM_COST,
-        });
+        assert!(session.queue_control_locked(&mut state, FrameType::Close, 7, &[]));
     }
     let first = session.poll_down_lane(7, 0).await.unwrap();
     let replay = session.poll_down_lane(7, 0).await.unwrap();
@@ -89,6 +227,10 @@ async fn drained_closed_lane_replays_then_signals_completion() {
     let finished = session.poll_down_lane(7, 1).await.unwrap();
     assert!(finished.body.is_empty());
     assert!(finished.lane_closed);
+    drop(first);
+    drop(replay);
+    session.close();
+    manager.shutdown().await;
 }
 
 #[test]
@@ -100,7 +242,7 @@ fn tombstone_eviction_releases_lane_budget_and_accepts_late_frames() {
     let session = session_with_limits(limits);
     {
         let mut state = session.state.lock();
-        state.carrier_lanes.insert(7, CarrierLane::new());
+        state.carrier_lanes.insert(7, CarrierLane::new(7));
         let encoded = frame::encode(FrameType::Close, 7, &[]);
         let cost = encoded.len() + QUEUE_ITEM_COST;
         state
@@ -120,7 +262,7 @@ fn tombstone_eviction_releases_lane_budget_and_accepts_late_frames() {
         state.pending_control_bytes = cost;
         state.pending_control_items = 1;
         session.remember_closed_locked(&mut state, 7);
-        state.carrier_lanes.insert(8, CarrierLane::new());
+        state.carrier_lanes.insert(8, CarrierLane::new(8));
         session.remember_closed_locked(&mut state, 8);
         assert!(!state.carrier_lanes.contains_key(&7));
         assert_eq!(state.pending_bytes, 0);
@@ -130,3 +272,17 @@ fn tombstone_eviction_releases_lane_budget_and_accepts_late_frames() {
     assert_eq!(session.process_up_lane(7, 7, &late), Ok(7));
     assert!(!session.state.lock().closed);
 }
+
+#[test]
+fn automatic_lane_does_not_ack_a_missing_lane_without_real_progress() {
+    let session =
+        new_session_with_automatic(WebLimitsConfig::default(), std::sync::Weak::new(), true);
+    let late = frame::encode(FrameType::Data, 7, b"late");
+
+    assert_eq!(
+        session.process_up_lane(7, 1, &late),
+        Err(ManagerError::Backpressure)
+    );
+    assert!(!session.is_carrier_committed());
+    assert!(!session.state.lock().closed);
+}

src/web/session/lifecycle.rs

@@ -0,0 +1,214 @@
+use std::sync::atomic::Ordering;
+use std::time::{Duration, Instant};
+
+use super::{SessionNegotiationPhase, WebSession};
+
+struct ReleasedQueues {
+    data_bytes: usize,
+    data_items: usize,
+    control_bytes: usize,
+    control_items: usize,
+}
+
+/// Deferred queue release after manager publication linearizes a supersede.
+#[must_use]
+pub(crate) struct CarrierSupersedeCompletion<'a> {
+    session: &'a WebSession,
+    released: ReleasedQueues,
+}
+
+impl CarrierSupersedeCompletion<'_> {
+    /// Releases process budgets and signals cancellation after manager locks are dropped.
+    pub(crate) fn finish(self) {
+        self.session.finish_close(self.released, true);
+    }
+}
+
+impl WebSession {
+    /// Closes carrier state while relay tasks retain their admission until exit.
+    pub(crate) fn close(&self) {
+        let Some(released) = self.begin_close(false, None) else {
+            return;
+        };
+        self.finish_close(released, false);
+    }
+
+    /// Atomically prevents first-frame commit while one successor is prepared.
+    pub(crate) fn begin_carrier_supersede(&self) -> bool {
+        let mut state = self.state.lock();
+        if state.closed || state.close_requested {
+            return false;
+        }
+        match state.negotiation_phase {
+            SessionNegotiationPhase::Uncommitted => {
+                state.negotiation_phase = SessionNegotiationPhase::Replacing;
+                true
+            }
+            SessionNegotiationPhase::Replacing
+            | SessionNegotiationPhase::Committed
+            | SessionNegotiationPhase::Superseded => false,
+        }
+    }
+
+    /// Restores an uncommitted attempt after successor admission failed.
+    pub(crate) fn cancel_carrier_supersede(&self) {
+        let close_requested = {
+            let mut state = self.state.lock();
+            if !state.closed && state.negotiation_phase == SessionNegotiationPhase::Replacing {
+                state.negotiation_phase = SessionNegotiationPhase::Uncommitted;
+            }
+            state.close_requested
+        };
+        if close_requested {
+            self.close();
+        }
+    }
+
+    /// Linearizes manager publication against close requests on the old token.
+    pub(crate) fn prepare_carrier_supersede(&self) -> Option<CarrierSupersedeCompletion<'_>> {
+        let released = self.begin_close(true, None)?;
+        Some(CarrierSupersedeCompletion {
+            session: self,
+            released,
+        })
+    }
+
+    /// Waits for all logical-stream tasks after admission has closed.
+    pub(crate) async fn wait(&self) {
+        loop {
+            let notified = self.tasks_done.notified();
+            if self.tasks_live.load(Ordering::Acquire) == 0 {
+                return;
+            }
+            notified.await;
+        }
+    }
+
+    /// Atomically closes a session only when reconnect grace is still due.
+    pub(crate) fn close_if_due(&self, now: Instant) -> bool {
+        let healthy = {
+            let mut state = self.state.lock();
+            self.carrier_health_ready_locked(&mut state, now)
+        };
+        if healthy {
+            self.finish_carrier_health();
+        }
+        let Some(released) = self.begin_close(false, Some(now)) else {
+            return false;
+        };
+        self.finish_close(released, false);
+        true
+    }
+
+    fn begin_close(&self, superseded: bool, idle_now: Option<Instant>) -> Option<ReleasedQueues> {
+        let mut state = self.state.lock();
+        if state.closed
+            || (superseded
+                && (state.negotiation_phase != SessionNegotiationPhase::Replacing
+                    || state.close_requested))
+        {
+            return None;
+        }
+        if let Some(now) = idle_now
+            && (state.negotiation_phase == SessionNegotiationPhase::Replacing
+                || now.saturating_duration_since(state.last_activity)
+                    < Duration::from_secs(self.timeouts.reconnect_grace_secs))
+        {
+            return None;
+        }
+        if !superseded && state.negotiation_phase == SessionNegotiationPhase::Replacing {
+            state.close_requested = true;
+            return None;
+        }
+        state.closed = true;
+        if superseded {
+            state.negotiation_phase = SessionNegotiationPhase::Superseded;
+        }
+        for stream in state.streams.values_mut() {
+            if let Some(waker) = stream.read_waker.take() {
+                waker.wake();
+            }
+            if let Some(waker) = stream.write_waker.take() {
+                waker.wake();
+            }
+        }
+        state.streams.clear();
+        state.pending_frames.clear();
+        state.pending_windows.clear();
+        if let Some(batch) = state.unacked.take() {
+            batch.lease.detach();
+            self.release_local_locked(&mut state, batch.data_bytes, batch.data_items, false);
+            self.release_local_locked(&mut state, batch.control_bytes, batch.control_items, true);
+        }
+        let mut lane_data_bytes = 0usize;
+        let mut lane_data_items = 0usize;
+        let mut lane_control_bytes = 0usize;
+        let mut lane_control_items = 0usize;
+        for lane in state.carrier_lanes.values_mut() {
+            lane.notify.notify_waiters();
+            if let Some(batch) = lane.unacked.take() {
+                batch.lease.detach();
+                lane_data_bytes = lane_data_bytes.saturating_add(batch.data_bytes);
+                lane_data_items = lane_data_items.saturating_add(batch.data_items);
+                lane_control_bytes = lane_control_bytes.saturating_add(batch.control_bytes);
+                lane_control_items = lane_control_items.saturating_add(batch.control_items);
+            }
+        }
+        self.release_local_locked(&mut state, lane_data_bytes, lane_data_items, false);
+        self.release_local_locked(&mut state, lane_control_bytes, lane_control_items, true);
+        state.carrier_lanes.clear();
+        let control_bytes = state.pending_control_bytes;
+        let control_items = state.pending_control_items;
+        let data_bytes = state.pending_bytes.saturating_sub(control_bytes);
+        let data_items = state.pending_items.saturating_sub(control_items);
+        state.pending_bytes = 0;
+        state.pending_items = 0;
+        state.pending_control_bytes = 0;
+        state.pending_control_items = 0;
+        Some(ReleasedQueues {
+            data_bytes,
+            data_items,
+            control_bytes,
+            control_items,
+        })
+    }
+
+    fn finish_close(&self, released: ReleasedQueues, superseded: bool) {
+        self.cancel.cancel();
+        if self.carrier().is_multiplexed() {
+            self.down_notify.notify_waiters();
+        }
+        if self.carrier().uses_lanes() {
+            self.lane_open_notify.notify_waiters();
+        }
+        if let Some(manager) = self.manager.upgrade() {
+            manager.release_pending(
+                self.profile_key,
+                released.data_bytes,
+                released.data_items,
+                false,
+            );
+            manager.release_pending(
+                self.profile_key,
+                released.control_bytes,
+                released.control_items,
+                true,
+            );
+            if !self.finished.swap(true, Ordering::AcqRel) {
+                self.trace_lifecycle(
+                    crate::web::trace::TraceLifecycleEvent::SessionClosed,
+                    None,
+                    Some(if superseded { "superseded" } else { "closed" }),
+                );
+                if !superseded {
+                    manager.session_finished(
+                        self.token_hash,
+                        self.client_ip,
+                        self.profile_key,
+                        &self.profile.host,
+                    );
+                }
+            }
+        }
+    }
+}

src/web/session/negotiation.rs

@@ -0,0 +1,329 @@
+use std::time::{Duration, Instant};
+
+use super::uplink::AppliedProgress;
+use super::{SessionNegotiationPhase, SessionState, WebSession};
+
+impl WebSession {
+    /// Returns whether accepted carrier progress made this attempt immutable.
+    pub(crate) fn is_carrier_committed(&self) -> bool {
+        self.state.lock().negotiation_phase == SessionNegotiationPhase::Committed
+    }
+
+    /// Rejects mutation after replacement, supersede, or the final chain deadline.
+    pub(super) fn ensure_carrier_active_locked(
+        &self,
+        state: &SessionState,
+    ) -> Result<(), crate::web::manager::ManagerError> {
+        if state.negotiation_phase == SessionNegotiationPhase::Uncommitted
+            && self
+                .carrier_deadline_at
+                .is_some_and(|deadline| Instant::now() >= deadline)
+        {
+            return Err(crate::web::manager::ManagerError::Closed);
+        }
+        match state.negotiation_phase {
+            SessionNegotiationPhase::Uncommitted | SessionNegotiationPhase::Committed => Ok(()),
+            SessionNegotiationPhase::Replacing | SessionNegotiationPhase::Superseded => {
+                Err(crate::web::manager::ManagerError::Closed)
+            }
+        }
+    }
+
+    /// Publishes the already-linearized session commit to process state.
+    pub(super) fn finish_carrier_commit(&self) {
+        let published = self.manager.upgrade().is_some_and(|manager| {
+            manager.carrier_committed(
+                self.bootstrap_hash,
+                self.token_hash,
+                self.carrier_attempt,
+                self.selected_carrier,
+                self.carrier_class,
+                self.client_ip,
+                self.trace_identity(),
+            )
+        });
+        if !published {
+            return;
+        }
+        let healthy = {
+            let mut state = self.state.lock();
+            if state.closed || state.negotiation_phase != SessionNegotiationPhase::Committed {
+                false
+            } else {
+                state.carrier_commit_published = true;
+                self.carrier_health_ready_locked(&mut state, Instant::now())
+            }
+        };
+        if healthy {
+            self.finish_carrier_health();
+        }
+    }
+
+    /// Publishes complete transport-specific health evidence to process state.
+    pub(super) fn finish_carrier_health(&self) {
+        if let Some(manager) = self.manager.upgrade() {
+            manager.carrier_became_healthy(
+                self.bootstrap_hash,
+                self.token_hash,
+                self.carrier_attempt,
+                self.selected_carrier,
+                self.carrier_class,
+                self.learning_context,
+                self.client_ip,
+                self.trace_identity(),
+            );
+        }
+    }
+
+    /// Records accepted OPEN or DATA progress and returns commit and health transitions.
+    pub(super) fn record_uplink_progress_locked(
+        &self,
+        state: &mut SessionState,
+        progress: AppliedProgress,
+    ) -> (bool, bool) {
+        if !self.automatic_carrier || !progress.any() {
+            return (false, false);
+        }
+        if self.selected_carrier.uses_websocket() {
+            state.websocket_carrier_active = true;
+            state.websocket_commit_ack_pending = true;
+        } else if progress.accepted_data {
+            state.carrier_health_uplink = true;
+        }
+        let now = Instant::now();
+        let committed = if state.negotiation_phase == SessionNegotiationPhase::Uncommitted {
+            state.negotiation_phase = SessionNegotiationPhase::Committed;
+            state.carrier_health_due_at =
+                Some(now + Duration::from_secs(self.timeouts.carrier_health_secs));
+            true
+        } else {
+            false
+        };
+        state.carrier_health_activity_at = Some(now);
+        let healthy = self.carrier_health_ready_locked(state, now);
+        (committed, healthy)
+    }
+
+    /// Consumes complete post-commit health evidence at most once.
+    pub(super) fn carrier_health_ready_locked(
+        &self,
+        state: &mut SessionState,
+        now: Instant,
+    ) -> bool {
+        if !self.automatic_carrier
+            || state.closed
+            || state.negotiation_phase != SessionNegotiationPhase::Committed
+            || !state.carrier_commit_published
+            || state.carrier_health_reported
+            || state.carrier_health_due_at.is_none_or(|due| now < due)
+        {
+            return false;
+        }
+        let evidence = if state.websocket_carrier_active {
+            state.websocket_probe_claimed
+                && state.websocket_commit_ack_owner.is_some()
+                && state.websocket_commit_ack_written
+                && state.carrier_health_uplink
+        } else {
+            state.carrier_health_uplink
+                && state.carrier_health_downlink
+                && state
+                    .carrier_health_activity_at
+                    .zip(state.carrier_health_due_at)
+                    .is_some_and(|(activity, due)| activity >= due)
+        };
+        if evidence {
+            state.carrier_health_reported = true;
+        }
+        evidence
+    }
+
+    /// Returns whether the exact automatic WebSocket owner must receive a commit acknowledgement.
+    pub(crate) fn needs_websocket_commit_ack(&self, owner: u64) -> bool {
+        let state = self.state.lock();
+        !state.closed
+            && state.websocket_commit_ack_owner == Some(owner)
+            && state.websocket_commit_ack_pending
+            && !state.websocket_commit_ack_written
+    }
+
+    /// Records that the commit acknowledgement reached its exact WebSocket owner.
+    pub(crate) fn websocket_commit_ack_written(&self, owner: u64) -> bool {
+        let mut state = self.state.lock();
+        if state.closed
+            || state.websocket_commit_ack_owner != Some(owner)
+            || !state.websocket_commit_ack_pending
+        {
+            return false;
+        }
+        state.websocket_commit_ack_written = true;
+        true
+    }
+
+    /// Records validated binary peer progress after the exact WebSocket acknowledgement.
+    pub(crate) fn websocket_peer_after_commit_ack(&self, owner: u64) -> bool {
+        let healthy = {
+            let mut state = self.state.lock();
+            if state.closed
+                || state.websocket_commit_ack_owner != Some(owner)
+                || !state.websocket_commit_ack_written
+            {
+                return false;
+            }
+            state.carrier_health_uplink = true;
+            let now = Instant::now();
+            state.carrier_health_activity_at = Some(now);
+            self.carrier_health_ready_locked(&mut state, now)
+        };
+        if healthy {
+            self.finish_carrier_health();
+        }
+        true
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::net::SocketAddr;
+    use std::sync::Arc;
+
+    use super::*;
+    use crate::config::{
+        WebCarrier, WebLimitsConfig, WebRuntimeProfile, WebSecretMode, WebTimeoutsConfig,
+    };
+    use crate::web::manager::{CarrierClientClass, WebProcessRuntime};
+
+    fn session(carrier: WebCarrier, deadline: Instant) -> Arc<WebSession> {
+        let profile = Arc::new(WebRuntimeProfile {
+            host: "proxy.example.com".to_string(),
+            public_addr: SocketAddr::from(([203, 0, 113, 10], 443)),
+            user: "alice".to_string(),
+            secret_mode: WebSecretMode::Plain,
+            carrier,
+            carrier_negotiation_enabled: true,
+            carrier_learning: false,
+            carriers: Arc::from([carrier]),
+            carrier_negotiation_deadlines_secs: [3, 5, 8, 12],
+            capability: [0; 32],
+            key_fingerprint: "0000000000000000".to_string(),
+            max_sessions: 1,
+            max_streams: 1,
+            max_streams_per_session: 1,
+        });
+        WebSession::new(
+            std::sync::Weak::<WebProcessRuntime>::new(),
+            [1; 32],
+            "192.0.2.10".parse().unwrap(),
+            1,
+            profile,
+            [2; 32],
+            carrier,
+            1,
+            [3; 32],
+            Some(deadline),
+            CarrierClientClass::Bridge,
+            None,
+            true,
+            WebLimitsConfig::default(),
+            WebTimeoutsConfig::default(),
+        )
+    }
+
+    #[test]
+    fn final_deadline_refuses_uncommitted_progress() {
+        let session = session(WebCarrier::Https, Instant::now() - Duration::from_secs(1));
+        let state = session.state.lock();
+        assert_eq!(
+            session.ensure_carrier_active_locked(&state),
+            Err(crate::web::manager::ManagerError::Closed)
+        );
+        assert!(matches!(
+            state.negotiation_phase,
+            SessionNegotiationPhase::Uncommitted
+        ));
+    }
+
+    #[test]
+    fn http_health_requires_authenticated_activity_after_the_window() {
+        let session = session(WebCarrier::Https, Instant::now() + Duration::from_secs(60));
+        let now = Instant::now();
+        let mut state = session.state.lock();
+        state.negotiation_phase = SessionNegotiationPhase::Committed;
+        state.carrier_commit_published = true;
+        state.carrier_health_due_at = Some(now - Duration::from_secs(1));
+        state.carrier_health_uplink = true;
+        state.carrier_health_downlink = true;
+        state.carrier_health_activity_at = Some(now - Duration::from_secs(2));
+        assert!(!session.carrier_health_ready_locked(&mut state, now));
+        state.carrier_health_activity_at = Some(now);
+        assert!(session.carrier_health_ready_locked(&mut state, now));
+    }
+
+    #[test]
+    fn websocket_health_requires_the_exact_live_probe_owner() {
+        let session = session(
+            WebCarrier::Websocket,
+            Instant::now() + Duration::from_secs(60),
+        );
+        let now = Instant::now();
+        let mut state = session.state.lock();
+        state.negotiation_phase = SessionNegotiationPhase::Committed;
+        state.carrier_commit_published = true;
+        state.carrier_health_due_at = Some(now - Duration::from_secs(1));
+        state.websocket_carrier_active = true;
+        state.websocket_commit_ack_owner = Some(7);
+        state.websocket_commit_ack_written = true;
+        state.carrier_health_uplink = true;
+        assert!(!session.carrier_health_ready_locked(&mut state, now));
+        state.websocket_probe_claimed = true;
+        assert!(session.carrier_health_ready_locked(&mut state, now));
+    }
+
+    #[test]
+    fn health_waits_for_manager_commit_publication() {
+        let session = session(WebCarrier::Https, Instant::now() + Duration::from_secs(60));
+        let now = Instant::now();
+        let mut state = session.state.lock();
+        state.negotiation_phase = SessionNegotiationPhase::Committed;
+        state.carrier_health_due_at = Some(now - Duration::from_secs(1));
+        state.carrier_health_uplink = true;
+        state.carrier_health_downlink = true;
+        state.carrier_health_activity_at = Some(now);
+
+        assert!(!session.carrier_health_ready_locked(&mut state, now));
+        assert!(!state.carrier_health_reported);
+    }
+
+    #[test]
+    fn commit_and_supersede_have_one_session_lock_winner() {
+        let committed = session(WebCarrier::Https, Instant::now() + Duration::from_secs(60));
+        {
+            let mut state = committed.state.lock();
+            assert!(
+                committed
+                    .record_uplink_progress_locked(
+                        &mut state,
+                        AppliedProgress {
+                            accepted_open: true,
+                            accepted_data: true,
+                        },
+                    )
+                    .0
+            );
+        }
+        assert!(!committed.begin_carrier_supersede());
+
+        let replacing = session(WebCarrier::Https, Instant::now() + Duration::from_secs(60));
+        assert!(replacing.begin_carrier_supersede());
+        assert_eq!(
+            replacing.ensure_carrier_active_locked(&replacing.state.lock()),
+            Err(crate::web::manager::ManagerError::Closed)
+        );
+        replacing.cancel_carrier_supersede();
+        assert!(
+            replacing
+                .ensure_carrier_active_locked(&replacing.state.lock())
+                .is_ok()
+        );
+    }
+}

src/web/session/resident.rs

@@ -0,0 +1,151 @@
+use std::sync::Arc;
+use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
+
+use bytes::Bytes;
+
+use super::WebSession;
+use crate::web::manager::{ProfileKey, WebProcessRuntime};
+
+#[derive(Clone, Copy, Default)]
+pub(super) struct PendingCounts {
+    pub(super) data_bytes: usize,
+    pub(super) data_items: usize,
+    pub(super) control_bytes: usize,
+    pub(super) control_items: usize,
+}
+
+impl PendingCounts {
+    pub(super) fn bytes(self) -> usize {
+        self.data_bytes.saturating_add(self.control_bytes)
+    }
+
+    pub(super) fn items(self) -> usize {
+        self.data_items.saturating_add(self.control_items)
+    }
+}
+
+#[derive(Default)]
+pub(super) struct ResidentCounters {
+    data_bytes: AtomicUsize,
+    data_items: AtomicUsize,
+    control_bytes: AtomicUsize,
+    control_items: AtomicUsize,
+}
+
+impl ResidentCounters {
+    pub(super) fn snapshot(&self) -> PendingCounts {
+        PendingCounts {
+            data_bytes: self.data_bytes.load(Ordering::Acquire),
+            data_items: self.data_items.load(Ordering::Acquire),
+            control_bytes: self.control_bytes.load(Ordering::Acquire),
+            control_items: self.control_items.load(Ordering::Acquire),
+        }
+    }
+
+    fn add(&self, counts: PendingCounts) {
+        self.data_bytes
+            .fetch_add(counts.data_bytes, Ordering::AcqRel);
+        self.data_items
+            .fetch_add(counts.data_items, Ordering::AcqRel);
+        self.control_bytes
+            .fetch_add(counts.control_bytes, Ordering::AcqRel);
+        self.control_items
+            .fetch_add(counts.control_items, Ordering::AcqRel);
+    }
+
+    fn remove(&self, counts: PendingCounts) {
+        self.data_bytes
+            .fetch_sub(counts.data_bytes, Ordering::AcqRel);
+        self.data_items
+            .fetch_sub(counts.data_items, Ordering::AcqRel);
+        self.control_bytes
+            .fetch_sub(counts.control_bytes, Ordering::AcqRel);
+        self.control_items
+            .fetch_sub(counts.control_items, Ordering::AcqRel);
+    }
+}
+
+pub(super) struct PendingResponseLease {
+    manager: std::sync::Weak<WebProcessRuntime>,
+    owner: ProfileKey,
+    counts: PendingCounts,
+    session: Arc<ResidentCounters>,
+    lane: Option<Arc<ResidentCounters>>,
+    detached: AtomicBool,
+}
+
+impl PendingResponseLease {
+    pub(super) fn new(
+        session: &WebSession,
+        counts: PendingCounts,
+        lane: Option<Arc<ResidentCounters>>,
+    ) -> Arc<Self> {
+        Arc::new(Self {
+            manager: session.manager.clone(),
+            owner: session.profile_key,
+            counts,
+            session: Arc::clone(&session.resident),
+            lane,
+            detached: AtomicBool::new(false),
+        })
+    }
+
+    pub(super) fn detach(&self) {
+        if self
+            .detached
+            .compare_exchange(false, true, Ordering::AcqRel, Ordering::Acquire)
+            .is_err()
+        {
+            return;
+        }
+        self.session.add(self.counts);
+        if let Some(lane) = &self.lane {
+            lane.add(self.counts);
+        }
+    }
+}
+
+impl Drop for PendingResponseLease {
+    fn drop(&mut self) {
+        if self.detached.load(Ordering::Acquire) {
+            self.session.remove(self.counts);
+            if let Some(lane) = &self.lane {
+                lane.remove(self.counts);
+            }
+        }
+        if let Some(manager) = self.manager.upgrade() {
+            manager.release_pending(
+                self.owner,
+                self.counts.data_bytes,
+                self.counts.data_items,
+                false,
+            );
+            manager.release_pending(
+                self.owner,
+                self.counts.control_bytes,
+                self.counts.control_items,
+                true,
+            );
+        }
+    }
+}
+
+pub(super) struct OwnedBatchBody {
+    bytes: Bytes,
+    _lease: Arc<PendingResponseLease>,
+}
+
+impl OwnedBatchBody {
+    pub(super) fn new(bytes: Bytes, lease: Arc<PendingResponseLease>) -> Self {
+        Self {
+            bytes,
+            _lease: lease,
+        }
+    }
+}
+
+impl AsRef<[u8]> for OwnedBatchBody {
+    fn as_ref(&self) -> &[u8] {
+        &self.bytes
+    }
+}

src/web/session/uplink.rs

@@ -7,13 +7,26 @@ use bytes::Bytes;
 use sha2::{Digest, Sha256};
 use subtle::ConstantTimeEq;
 
+use super::backend::StreamCompletion;
 use super::{
-    InboundChunk, PendingClass, QUEUE_ITEM_COST, SessionState, StreamState, WebSession,
-    inbound_queue_cost,
+    InboundChunk, PendingClass, QUEUE_ITEM_COST, SessionState, StreamIdentity, StreamState,
+    WebSession, inbound_queue_cost,
 };
 use crate::web::frame::{self, Frame, FrameType};
 use crate::web::manager::{ManagerError, TokenHash};
 
+#[derive(Clone, Copy, Default)]
+pub(super) struct AppliedProgress {
+    pub(super) accepted_open: bool,
+    pub(super) accepted_data: bool,
+}
+
+impl AppliedProgress {
+    pub(super) fn any(self) -> bool {
+        self.accepted_open || self.accepted_data
+    }
+}
+
 impl WebSession {
     /// Applies one exactly-once uplink batch.
     pub(crate) fn process_up(
@@ -21,6 +34,28 @@ impl WebSession {
         sequence: u64,
         body: &[u8],
     ) -> Result<u64, ManagerError> {
+        let (acknowledged, progressed) = self.process_up_inner(sequence, body)?;
+        if self.automatic_carrier && !progressed && !self.is_carrier_committed() {
+            return Err(ManagerError::Backpressure);
+        }
+        Ok(acknowledged)
+    }
+
+    /// Applies one WebSocket uplink batch and reports actual carrier progress.
+    pub(crate) fn process_websocket_multiplex(
+        self: &Arc<Self>,
+        sequence: u64,
+        body: &[u8],
+    ) -> Result<bool, ManagerError> {
+        self.process_up_inner(sequence, body)
+            .map(|(_, progress)| progress)
+    }
+
+    fn process_up_inner(
+        self: &Arc<Self>,
+        sequence: u64,
+        body: &[u8],
+    ) -> Result<(u64, bool), ManagerError> {
         if !self.carrier().is_multiplexed() {
             return Err(ManagerError::Protocol);
         }
@@ -49,15 +84,18 @@ impl WebSession {
         }
         let digest: TokenHash = Sha256::digest(body).into();
         let mut opened = Vec::new();
+        let mut committed = false;
+        let mut healthy = false;
         let result = {
             let mut state = self.state.lock();
             if state.closed {
                 return Err(ManagerError::Closed);
             }
+            self.ensure_carrier_active_locked(&state)?;
             state.last_activity = Instant::now();
             if sequence == state.last_up_sequence && sequence != 0 {
                 return if bool::from(state.last_up_digest.ct_eq(&digest)) {
-                    Ok(sequence)
+                    Ok((sequence, false))
                 } else {
                     drop(state);
                     self.close();
@@ -85,6 +123,7 @@ impl WebSession {
             }
             let mut unused_bytes = reserve_bytes;
             let mut unused_items = reserve_items;
+            let mut progress = AppliedProgress::default();
             let applied = self.apply_batch_locked(
                 &mut state,
                 &frames,
@@ -92,6 +131,7 @@ impl WebSession {
                 &mut None,
                 &mut unused_bytes,
                 &mut unused_items,
+                &mut progress,
             );
             self.release_locked(&mut state, unused_bytes, unused_items, false);
             if !applied {
@@ -99,7 +139,8 @@ impl WebSession {
             } else {
                 state.last_up_sequence = sequence;
                 state.last_up_digest = digest;
-                Ok(sequence)
+                (committed, healthy) = self.record_uplink_progress_locked(&mut state, progress);
+                Ok((sequence, progress.any()))
             }
         };
         if matches!(result, Err(ManagerError::Backpressure)) {
@@ -107,13 +148,17 @@ impl WebSession {
         }
         if result.is_err() {
             self.close();
-            for (_, peer_port) in opened {
-                self.release_stream_reservation(peer_port);
-            }
+            drop(opened);
             return result;
         }
-        for (stream_id, peer_port) in opened {
-            self.spawn_stream(stream_id, peer_port, false);
+        if committed {
+            self.finish_carrier_commit();
+        }
+        if healthy {
+            self.finish_carrier_health();
+        }
+        for completion in opened {
+            self.spawn_stream(completion, false);
         }
         if let Some(manager) = self.manager.upgrade() {
             manager.record_up(body.len());
@@ -122,21 +167,26 @@ impl WebSession {
     }
 
     pub(super) fn apply_batch_locked(
-        &self,
+        self: &Arc<Self>,
         state: &mut SessionState,
         frames: &[Frame<'_>],
-        opened: &mut Vec<(u32, u16)>,
+        opened: &mut Vec<StreamCompletion>,
         reserved_open: &mut Option<(u32, u16)>,
         unused_bytes: &mut usize,
         unused_items: &mut usize,
+        progress: &mut AppliedProgress,
     ) -> bool {
         for value in frames {
             if value.stream_id == 0 {
                 continue;
             }
-            let was_closed = state.closed_streams.contains(&value.stream_id);
+            let was_closed = state.closed_streams.contains(&value.stream_id)
+                || state.closing_streams.contains_key(&value.stream_id);
             match value.frame_type {
                 FrameType::Open => {
+                    let Some(stream) = next_stream_identity(state, value.stream_id) else {
+                        return false;
+                    };
                     let peer_port = match reserved_open.take() {
                         Some((reserved_stream_id, peer_port))
                             if reserved_stream_id == value.stream_id =>
@@ -166,6 +216,7 @@ impl WebSession {
                     state.streams.insert(
                         value.stream_id,
                         StreamState {
+                            instance: stream.instance,
                             inbound: VecDeque::new(),
                             receive_window: frame::INITIAL_STREAM_WINDOW,
                             send_credit: u64::from(frame::INITIAL_STREAM_WINDOW),
@@ -173,7 +224,8 @@ impl WebSession {
                             write_waker: None,
                         },
                     );
-                    opened.push((value.stream_id, peer_port));
+                    progress.accepted_open = true;
+                    opened.push(self.own_stream_task(stream, peer_port));
                 }
                 FrameType::Data if !was_closed => {
                     let Some(stream) = state.streams.get_mut(&value.stream_id) else {
@@ -184,6 +236,7 @@ impl WebSession {
                         bytes: Bytes::copy_from_slice(value.payload),
                         offset: 0,
                     });
+                    progress.accepted_data = true;
                     *unused_bytes =
                         unused_bytes.saturating_sub(value.payload.len() + QUEUE_ITEM_COST);
                     *unused_items = unused_items.saturating_sub(1);
@@ -208,6 +261,9 @@ impl WebSession {
                     let Some(stream) = state.streams.remove(&value.stream_id) else {
                         return false;
                     };
+                    state
+                        .closing_streams
+                        .insert(value.stream_id, stream.instance);
                     let (bytes, items) = inbound_queue_cost(&stream.inbound);
                     self.release_locked(state, bytes, items, false);
                     self.remember_closed_locked(state, value.stream_id);
@@ -249,6 +305,15 @@ impl WebSession {
     }
 }
 
+fn next_stream_identity(state: &mut SessionState, stream_id: u32) -> Option<StreamIdentity> {
+    let instance = state.next_stream_instance;
+    state.next_stream_instance = instance.checked_add(1)?;
+    Some(StreamIdentity {
+        id: stream_id,
+        instance,
+    })
+}
+
 struct UplinkGuard<'a>(&'a AtomicBool);
 
 impl Drop for UplinkGuard<'_> {
@@ -271,8 +336,9 @@ pub(super) fn validate_batch(state: &SessionState, frames: &[Frame<'_>]) -> bool
             }
             continue;
         }
-        let was_closed =
-            state.closed_streams.contains(&value.stream_id) || closed.contains(&value.stream_id);
+        let was_closed = state.closed_streams.contains(&value.stream_id)
+            || state.closing_streams.contains_key(&value.stream_id)
+            || closed.contains(&value.stream_id);
         match value.frame_type {
             FrameType::Open => {
                 if live.contains_key(&value.stream_id) || was_closed {
@@ -356,12 +422,20 @@ mod tests {
     use crate::web::manager::WebProcessRuntime;
 
     fn session() -> Arc<WebSession> {
+        session_with_automatic(false)
+    }
+
+    fn session_with_automatic(automatic: bool) -> Arc<WebSession> {
         let profile = Arc::new(WebRuntimeProfile {
             host: "proxy.example.com".to_string(),
             public_addr: SocketAddr::from(([203, 0, 113, 10], 443)),
             user: "alice".to_string(),
             secret_mode: WebSecretMode::Plain,
             carrier: WebCarrier::Https,
+            carrier_negotiation_enabled: false,
+            carrier_learning: true,
+            carriers: Arc::from([WebCarrier::Https]),
+            carrier_negotiation_deadlines_secs: [3, 5, 8, 12],
             capability: [0; 32],
             key_fingerprint: "0000000000000000".to_string(),
             max_sessions: 1,
@@ -375,6 +449,17 @@ mod tests {
             1,
             profile,
             [2; 32],
+            WebCarrier::Https,
+            1,
+            [3; 32],
+            None,
+            if automatic {
+                crate::web::manager::CarrierClientClass::Bridge
+            } else {
+                crate::web::manager::CarrierClientClass::Legacy
+            },
+            None,
+            automatic,
             WebLimitsConfig::default(),
             WebTimeoutsConfig::default(),
         )
@@ -411,6 +496,7 @@ mod tests {
             state.streams.insert(
                 1,
                 StreamState {
+                    instance: 1,
                     inbound: VecDeque::new(),
                     receive_window: frame::INITIAL_STREAM_WINDOW,
                     send_credit: u64::from(frame::INITIAL_STREAM_WINDOW),
@@ -439,4 +525,17 @@ mod tests {
         assert_eq!(session.process_up(2, &body), Err(ManagerError::Protocol));
         assert!(session.state.lock().closed);
     }
+
+    #[test]
+    fn automatic_uplink_does_not_ack_a_batch_without_real_progress() {
+        let session = session_with_automatic(true);
+        let body = frame::encode(FrameType::Pong, 0, &[]);
+
+        assert_eq!(
+            session.process_up(1, &body),
+            Err(ManagerError::Backpressure)
+        );
+        assert!(!session.is_carrier_committed());
+        assert!(!session.state.lock().closed);
+    }
 }

src/web/session/websocket.rs

@@ -3,8 +3,8 @@ use std::time::Instant;
 
 use sha2::{Digest, Sha256};
 
-use super::uplink::{inbound_reservation, validate_batch};
-use super::{CarrierLane, PendingClass, WebSession, inbound_queue_cost};
+use super::uplink::{AppliedProgress, inbound_reservation, validate_batch};
+use super::{PendingClass, WebSession, inbound_queue_cost, insert_carrier_lane};
 use crate::config::WebCarrier;
 use crate::web::frame;
 use crate::web::manager::ManagerError;
@@ -17,6 +17,43 @@ pub(crate) struct WebSocketLaneReservation {
     transferred: bool,
 }
 
+/// Session-wide ownership of the only automatic WebSocket carrier probe.
+pub(crate) struct WebSocketProbeReservation {
+    session: Arc<WebSession>,
+    owner: Option<u64>,
+}
+
+impl WebSocketProbeReservation {
+    /// Binds the admitted process connection to the future commit acknowledgement.
+    pub(crate) fn bind(&mut self, owner: u64) -> Result<(), ManagerError> {
+        let mut state = self.session.state.lock();
+        if state.closed
+            || !state.websocket_probe_claimed
+            || state.websocket_commit_ack_owner.is_some()
+        {
+            return Err(ManagerError::Closed);
+        }
+        state.websocket_commit_ack_owner = Some(owner);
+        self.owner = Some(owner);
+        Ok(())
+    }
+}
+
+impl Drop for WebSocketProbeReservation {
+    fn drop(&mut self) {
+        let mut state = self.session.state.lock();
+        state.websocket_probe_claimed = false;
+        if state.websocket_commit_ack_owner == self.owner {
+            state.websocket_commit_ack_owner = None;
+            if !state.carrier_health_reported {
+                state.websocket_commit_ack_written = false;
+                state.carrier_health_uplink = false;
+                state.carrier_health_activity_at = None;
+            }
+        }
+    }
+}
+
 impl WebSocketLaneReservation {
     /// Returns the logical stream owned by this connection.
     pub(crate) fn lane_id(&self) -> u32 {
@@ -46,6 +83,42 @@ impl Drop for WebSocketLaneReservation {
 }
 
 impl WebSession {
+    /// Reserves the only automatic WebSocket probe before any HTTP 101 response.
+    pub(crate) fn reserve_websocket_probe(
+        self: &Arc<Self>,
+        acknowledge_commit: bool,
+    ) -> Result<Option<WebSocketProbeReservation>, ManagerError> {
+        let mut state = self.state.lock();
+        if state.closed {
+            return Err(ManagerError::Closed);
+        }
+        self.ensure_carrier_active_locked(&state)?;
+        if !self.automatic_carrier {
+            return if acknowledge_commit {
+                Err(ManagerError::Protocol)
+            } else {
+                Ok(None)
+            };
+        }
+        match state.negotiation_phase {
+            super::SessionNegotiationPhase::Uncommitted if acknowledge_commit => {
+                if state.websocket_probe_claimed || state.websocket_commit_ack_owner.is_some() {
+                    return Err(ManagerError::Concurrent);
+                }
+                state.websocket_probe_claimed = true;
+                Ok(Some(WebSocketProbeReservation {
+                    session: Arc::clone(self),
+                    owner: None,
+                }))
+            }
+            super::SessionNegotiationPhase::Committed if !acknowledge_commit => Ok(None),
+            super::SessionNegotiationPhase::Committed => Err(ManagerError::Committed),
+            super::SessionNegotiationPhase::Uncommitted => Err(ManagerError::Protocol),
+            super::SessionNegotiationPhase::Replacing
+            | super::SessionNegotiationPhase::Superseded => Err(ManagerError::Closed),
+        }
+    }
+
     /// Acquires stream quota and tuple ownership before a lane returns HTTP 101.
     pub(crate) fn reserve_websocket_lane(
         self: &Arc<Self>,
@@ -63,6 +136,7 @@ impl WebSession {
         }
         if state.active_peer_ports.len() >= self.profile.max_streams_per_session
             || state.streams.contains_key(&lane_id)
+            || state.closing_streams.contains_key(&lane_id)
             || state.closed_streams.contains(&lane_id)
             || state.websocket_lane_reservations.contains_key(&lane_id)
         {
@@ -89,7 +163,19 @@ impl WebSession {
             return Err(ManagerError::Limit);
         }
         state.websocket_lane_reservations.insert(lane_id, peer_port);
-        state.carrier_lanes.insert(lane_id, CarrierLane::new());
+        if insert_carrier_lane(&mut state, lane_id).is_none() {
+            state.websocket_lane_reservations.remove(&lane_id);
+            state.active_peer_ports.remove(&peer_port);
+            manager.release_stream(
+                self.profile_key,
+                self.client_ip,
+                self.profile.public_addr,
+                peer_port,
+            );
+            return Err(ManagerError::Protocol);
+        }
+        drop(state);
+        self.lane_open_notify.notify_waiters();
         Ok(WebSocketLaneReservation {
             session: Arc::clone(self),
             lane_id,
@@ -104,7 +190,7 @@ impl WebSession {
         reservation: &mut WebSocketLaneReservation,
         sequence: u64,
         body: &[u8],
-    ) -> Result<(), ManagerError> {
+    ) -> Result<bool, ManagerError> {
         if !Arc::ptr_eq(self, &reservation.session)
             || reservation.lane_id == 0
             || reservation.lane_id > frame::MAX_STREAM_ID
@@ -122,11 +208,14 @@ impl WebSession {
         }
         let digest = Sha256::digest(body).into();
         let mut opened = Vec::new();
+        let mut committed = false;
+        let mut healthy = false;
         let result = {
             let mut state = self.state.lock();
             if state.closed {
                 return Err(ManagerError::Closed);
             }
+            self.ensure_carrier_active_locked(&state)?;
             if !reservation.transferred
                 && state.websocket_lane_reservations.get(&lane_id) != Some(&reservation.peer_port)
             {
@@ -162,6 +251,7 @@ impl WebSession {
             }
             let mut unused_bytes = reserve_bytes;
             let mut unused_items = reserve_items;
+            let mut progress = AppliedProgress::default();
             let mut reserved_open =
                 (!reservation.transferred).then_some((lane_id, reservation.peer_port));
             let applied = self.apply_batch_locked(
@@ -171,6 +261,7 @@ impl WebSession {
                 &mut reserved_open,
                 &mut unused_bytes,
                 &mut unused_items,
+                &mut progress,
             );
             self.release_locked(&mut state, unused_bytes, unused_items, false);
             if let Some(lane) = state.carrier_lanes.get_mut(&lane_id) {
@@ -181,14 +272,25 @@ impl WebSession {
                 }
             }
             state.last_activity = Instant::now();
-            applied.then_some(()).ok_or(ManagerError::Protocol)
+            if applied {
+                (committed, healthy) = self.record_uplink_progress_locked(&mut state, progress);
+            }
+            applied
+                .then_some(progress.any())
+                .ok_or(ManagerError::Protocol)
         };
-        result?;
-        for (stream_id, peer_port) in opened {
-            if stream_id != lane_id || peer_port != reservation.peer_port {
+        let progressed = result?;
+        if committed {
+            self.finish_carrier_commit();
+        }
+        if healthy {
+            self.finish_carrier_health();
+        }
+        for completion in opened {
+            if completion.stream.id != lane_id || completion.peer_port != reservation.peer_port {
                 return Err(ManagerError::Protocol);
             }
-            if !self.spawn_stream(stream_id, peer_port, true) {
+            if !self.spawn_stream(completion, true) {
                 return Err(ManagerError::Limit);
             }
             reservation.transfer_to_stream();
@@ -199,7 +301,7 @@ impl WebSession {
         if let Some(manager) = self.manager.upgrade() {
             manager.record_up(body.len());
         }
-        Ok(())
+        Ok(progressed)
     }
 
     /// Ends one failed or disconnected lane without closing its parent session.
@@ -208,6 +310,7 @@ impl WebSession {
             let mut state = self.state.lock();
             let reserved = state.websocket_lane_reservations.remove(&lane_id);
             if let Some(stream) = state.streams.remove(&lane_id) {
+                state.closing_streams.insert(lane_id, stream.instance);
                 let (bytes, items) = inbound_queue_cost(&stream.inbound);
                 self.release_locked(&mut state, bytes, items, false);
                 if let Some(waker) = stream.read_waker {
@@ -224,6 +327,7 @@ impl WebSession {
         if let Some(peer_port) = reserved {
             self.release_websocket_lane_reservation(lane_id, peer_port);
         }
+        self.lane_open_notify.notify_waiters();
     }
 
     fn release_websocket_lane_reservation(&self, lane_id: u32, peer_port: u16) {

src/web/session/websocket/tests.rs

@@ -33,6 +33,10 @@ fn runtime(admission: bool) -> TestRuntime {
         user: "default".to_string(),
         secret_mode: WebSecretMode::Plain,
         carrier: WebCarrier::WebsocketLanes,
+        carrier_negotiation_enabled: false,
+        carrier_learning: true,
+        carriers: Arc::from([WebCarrier::WebsocketLanes]),
+        carrier_negotiation_deadlines_secs: [3, 5, 8, 12],
         capability: [7; 32],
         key_fingerprint: "0000000000000000".to_string(),
         max_sessions: 2,
@@ -60,6 +64,13 @@ fn runtime(admission: bool) -> TestRuntime {
         1,
         profile,
         [7; 32],
+        WebCarrier::WebsocketLanes,
+        1,
+        [9; 32],
+        None,
+        crate::web::manager::CarrierClientClass::Legacy,
+        None,
+        false,
         limits,
         timeouts,
     );

src/web/stream.rs

@@ -7,21 +7,21 @@ use std::task::{Context, Poll};
 use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
 use tokio::sync::futures::OwnedNotified;
 
-use crate::web::session::WebSession;
+use crate::web::session::{StreamIdentity, WebSession};
 
 /// Async byte stream that maps one WEB stream identifier onto carrier frames.
 pub(crate) struct WebLogicalStream {
     session: Arc<WebSession>,
-    stream_id: u32,
+    stream: StreamIdentity,
     budget_wait: Option<Pin<Box<OwnedNotified>>>,
 }
 
 impl WebLogicalStream {
     /// Binds a virtual byte stream to one live carrier stream identifier.
-    pub(crate) fn new(session: Arc<WebSession>, stream_id: u32) -> Self {
+    pub(crate) fn new(session: Arc<WebSession>, stream: StreamIdentity) -> Self {
         Self {
             session,
-            stream_id,
+            stream,
             budget_wait: None,
         }
     }
@@ -33,7 +33,7 @@ impl AsyncRead for WebLogicalStream {
         cx: &mut Context<'_>,
         output: &mut ReadBuf<'_>,
     ) -> Poll<io::Result<()>> {
-        self.session.poll_read(self.stream_id, cx, output)
+        self.session.poll_read(self.stream, cx, output)
     }
 }
 
@@ -43,7 +43,7 @@ impl AsyncWrite for WebLogicalStream {
         cx: &mut Context<'_>,
         input: &[u8],
     ) -> Poll<io::Result<usize>> {
-        let result = self.session.poll_write(self.stream_id, cx, input);
+        let result = self.session.poll_write(self.stream, cx, input);
         if !result.is_pending() {
             self.budget_wait = None;
             return result;
@@ -64,7 +64,7 @@ impl AsyncWrite for WebLogicalStream {
             }
             self.budget_wait = None;
         }
-        match self.session.poll_write(self.stream_id, cx, input) {
+        match self.session.poll_write(self.stream, cx, input) {
             Poll::Ready(result) => {
                 self.budget_wait = None;
                 Poll::Ready(result)

src/web/trace/exchange.rs

@@ -81,10 +81,11 @@ impl HttpTraceExchange {
                     .headers()
                     .get(hyper::header::USER_AGENT)
                     .map(|value| bounded_text(value.as_bytes(), USER_AGENT_MAX_BYTES)),
-                policy
-                    .capture_headers
-                    .then(|| sanitized_headers(request.headers()))
-                    .unwrap_or_default(),
+                if policy.capture_headers {
+                    sanitized_headers(request.headers())
+                } else {
+                    Vec::new()
+                },
                 sensitive_values(request.headers(), request.uri().query()),
             )
         } else {
@@ -423,13 +424,17 @@ mod tests {
             .header("authorization", format!("Bearer {request_token}"))
             .body(())
             .unwrap();
-        let mut policy = WebDebugConfig::default();
-        policy.enabled = true;
-        policy.body_capture = WebDebugBodyCapture::Prefix;
-        policy.body_prefix_bytes = 256;
-        let mut limits = WebLimitsConfig::default();
-        limits.debug_records_capacity = 4;
-        limits.debug_bytes_global = 16 * 1024;
+        let policy = WebDebugConfig {
+            enabled: true,
+            body_capture: WebDebugBodyCapture::Prefix,
+            body_prefix_bytes: 256,
+            ..Default::default()
+        };
+        let limits = WebLimitsConfig {
+            debug_records_capacity: 4,
+            debug_bytes_global: 16 * 1024,
+            ..Default::default()
+        };
         let store = WebTraceStore::new(policy, &limits);
         let exchange = store
             .begin_http(&request, "192.0.2.30".parse().unwrap())

src/web/trace/mod.rs

@@ -13,5 +13,6 @@ pub(crate) use exchange::HttpTraceExchange;
 pub(crate) use store::{StoredTraceRecord, WebTraceStore, epoch_millis as store_epoch_millis};
 pub(crate) use types::{
     TraceBodySnapshot, TraceBodyState, TraceDirection, TraceFrame, TraceHeader, TraceIdentity,
-    TraceLifecycleEvent, TraceRecord, TraceRecordKind, TraceRoute, TraceWebSocketContext,
+    TraceLifecycleEvent, TraceLifecycleRecord, TraceRecord, TraceRecordKind, TraceRoute,
+    TraceWebSocketContext,
 };

src/web/trace/sanitize.rs

@@ -28,12 +28,11 @@ pub(super) fn request_dynamic_bytes<B>(
                     lossy_text_reservation(value.as_bytes(), USER_AGENT_MAX_BYTES)
                 }),
         )
-        .saturating_add(
-            policy
-                .capture_headers
-                .then(|| sanitized_header_bytes(request.headers()))
-                .unwrap_or(0),
-        )
+        .saturating_add(if policy.capture_headers {
+            sanitized_header_bytes(request.headers())
+        } else {
+            0
+        })
         .saturating_add(sensitive_value_bytes(
             request.headers(),
             request.uri().query(),
@@ -45,10 +44,11 @@ pub(super) fn response_dynamic_bytes<B>(
     response: &hyper::Response<B>,
     policy: &WebDebugConfig,
 ) -> usize {
-    policy
-        .capture_headers
-        .then(|| sanitized_header_bytes(response.headers()))
-        .unwrap_or(0)
+    if policy.capture_headers {
+        sanitized_header_bytes(response.headers())
+    } else {
+        0
+    }
     .saturating_add(sensitive_value_bytes(response.headers(), None))
 }
 
@@ -173,11 +173,11 @@ fn sanitized_header_bytes(headers: &hyper::HeaderMap) -> usize {
         total
             .saturating_add(std::mem::size_of::<TraceHeader>())
             .saturating_add(name.as_str().len())
-            .saturating_add(
-                header_value_allowed(name)
-                    .then(|| lossy_text_reservation(value.as_bytes(), 4096))
-                    .unwrap_or(0),
-            )
+            .saturating_add(if header_value_allowed(name) {
+                lossy_text_reservation(value.as_bytes(), 4096)
+            } else {
+                0
+            })
     })
 }
 
@@ -195,6 +195,8 @@ fn header_value_allowed(name: &hyper::header::HeaderName) -> bool {
             | "x-down-cursor"
             | "x-lane-id"
             | "x-lane-closed"
+            | "x-carrier-attempt"
+            | "x-carrier-failure"
             | "x-carrier-mode"
             | "retry-after"
             | "cache-control"
@@ -273,9 +275,11 @@ mod tests {
 
     #[test]
     fn full_capture_keeps_decoy_bodies_prefix_bounded() {
-        let mut policy = WebDebugConfig::default();
-        policy.body_capture = WebDebugBodyCapture::Full;
-        policy.decoy_body_prefix_bytes = 123;
+        let policy = WebDebugConfig {
+            body_capture: WebDebugBodyCapture::Full,
+            decoy_body_prefix_bytes: 123,
+            ..Default::default()
+        };
         assert_eq!(capture_limit(&policy, TraceRoute::Decoy, 4096), Some(123));
         assert_eq!(capture_limit(&policy, TraceRoute::Uplink, 4096), Some(4096));
     }

src/web/trace/store.rs

@@ -9,7 +9,8 @@ use tokio::sync::{OwnedSemaphorePermit, Semaphore};
 
 use super::exchange::HttpTraceExchange;
 use super::types::{
-    TraceIdentity, TraceLifecycleEvent, TraceLifecycleRecord, TraceRecord, TraceRecordKind,
+    TraceCarrierDetail, TraceIdentity, TraceLifecycleEvent, TraceLifecycleRecord, TraceRecord,
+    TraceRecordKind,
 };
 use crate::config::{WebDebugConfig, WebLimitsConfig};
 
@@ -166,6 +167,57 @@ impl WebTraceStore {
         event: TraceLifecycleEvent,
         stream_id: Option<u32>,
         reason: Option<&'static str>,
+    ) {
+        self.record_lifecycle_detail(
+            peer_ip,
+            effective_ip,
+            identity,
+            event,
+            stream_id,
+            reason,
+            None,
+        );
+    }
+
+    /// Records one carrier transition with structured, non-secret negotiation fields.
+    #[allow(clippy::too_many_arguments)]
+    pub(crate) fn record_carrier_lifecycle(
+        &self,
+        effective_ip: IpAddr,
+        identity: TraceIdentity,
+        event: TraceLifecycleEvent,
+        client_class: &'static str,
+        carrier: crate::config::WebCarrier,
+        attempt: u8,
+        scores: [i16; 4],
+        reason: Option<&'static str>,
+    ) {
+        self.record_lifecycle_detail(
+            None,
+            Some(effective_ip),
+            identity,
+            event,
+            None,
+            reason,
+            Some(TraceCarrierDetail {
+                client_class,
+                carrier,
+                attempt,
+                scores,
+            }),
+        );
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    fn record_lifecycle_detail(
+        &self,
+        peer_ip: Option<IpAddr>,
+        effective_ip: Option<IpAddr>,
+        identity: TraceIdentity,
+        event: TraceLifecycleEvent,
+        stream_id: Option<u32>,
+        reason: Option<&'static str>,
+        carrier: Option<TraceCarrierDetail>,
     ) {
         if !self.enabled.load(Ordering::Acquire) {
             return;
@@ -197,6 +249,7 @@ impl WebTraceStore {
                 event,
                 stream_id,
                 reason,
+                carrier,
             }),
         };
         if !self.try_commit(record, reservation, epoch) {
@@ -378,11 +431,15 @@ mod tests {
     use super::*;
 
     fn store(records_capacity: usize, bytes_capacity: usize) -> Arc<WebTraceStore> {
-        let mut policy = WebDebugConfig::default();
-        policy.enabled = true;
-        let mut limits = WebLimitsConfig::default();
-        limits.debug_records_capacity = records_capacity;
-        limits.debug_bytes_global = bytes_capacity;
+        let policy = WebDebugConfig {
+            enabled: true,
+            ..Default::default()
+        };
+        let limits = WebLimitsConfig {
+            debug_records_capacity: records_capacity,
+            debug_bytes_global: bytes_capacity,
+            ..Default::default()
+        };
         WebTraceStore::new(policy, &limits)
     }
 
@@ -427,9 +484,11 @@ mod tests {
             .begin_http(&request, "192.0.2.20".parse().unwrap())
             .unwrap();
 
-        let mut changed = WebDebugConfig::default();
-        changed.enabled = true;
-        changed.capture_headers = false;
+        let changed = WebDebugConfig {
+            enabled: true,
+            capture_headers: false,
+            ..Default::default()
+        };
         store.apply_policy(&changed);
         exchange.commit();
 

src/web/trace/store/websocket.rs

@@ -65,16 +65,15 @@ impl WebTraceStore {
         )
         .unwrap_or(0);
         let capture_bytes = payload.len().min(capture_limit);
-        let frame_reservation = policy
-            .capture_frames
-            .then(|| {
+        let frame_reservation = if policy.capture_frames {
             payload
                 .len()
                 .div_ceil(frame::HEADER_BYTES)
                 .clamp(1, self.frame_limits.max_frames_per_body)
                 .saturating_mul(std::mem::size_of::<TraceFrame>())
-            })
-            .unwrap_or(0);
+        } else {
+            0
+        };
         let identity_bytes = context
             .identity
             .user
@@ -168,14 +167,18 @@ mod tests {
 
     #[test]
     fn websocket_message_capture_retains_bounded_identity_body_timing_and_frames() {
-        let mut policy = WebDebugConfig::default();
-        policy.enabled = true;
-        policy.capture_frames = true;
-        policy.capture_timings = true;
-        policy.body_capture = WebDebugBodyCapture::Full;
-        let mut limits = WebLimitsConfig::default();
-        limits.debug_records_capacity = 4;
-        limits.debug_bytes_global = 64 * 1024;
+        let policy = WebDebugConfig {
+            enabled: true,
+            capture_frames: true,
+            capture_timings: true,
+            body_capture: WebDebugBodyCapture::Full,
+            ..Default::default()
+        };
+        let limits = WebLimitsConfig {
+            debug_records_capacity: 4,
+            debug_bytes_global: 64 * 1024,
+            ..Default::default()
+        };
         let store = WebTraceStore::new(policy, &limits);
         let request = hyper::Request::builder()
             .header(hyper::header::USER_AGENT, "trace-client")

src/web/trace/types.rs

@@ -228,6 +228,18 @@ pub(crate) enum TraceLifecycleEvent {
     BridgeIssued,
     /// Bootstrap or bridge admission was rejected.
     BootstrapRejected,
+    /// A session request was classified for legacy or automatic negotiation.
+    CarrierClassified,
+    /// One carrier candidate was selected for an attempt.
+    CarrierSelected,
+    /// A provisional carrier was reported failed by the bridge.
+    CarrierFailed,
+    /// An uncommitted carrier session was atomically superseded.
+    CarrierSuperseded,
+    /// Bidirectional carrier evidence made replacement unsafe.
+    CarrierCommitted,
+    /// A committed carrier survived its configured health interval.
+    CarrierHealthy,
     /// A new session was created.
     SessionCreated,
     /// An idempotent session creation was replayed.
@@ -264,6 +276,12 @@ impl TraceLifecycleEvent {
         match self {
             Self::BridgeIssued => "bridge_issued",
             Self::BootstrapRejected => "bootstrap_rejected",
+            Self::CarrierClassified => "carrier_classified",
+            Self::CarrierSelected => "carrier_selected",
+            Self::CarrierFailed => "carrier_failed",
+            Self::CarrierSuperseded => "carrier_superseded",
+            Self::CarrierCommitted => "carrier_committed",
+            Self::CarrierHealthy => "carrier_healthy",
             Self::SessionCreated => "session_created",
             Self::SessionReplayed => "session_replayed",
             Self::SessionRejected => "session_rejected",
@@ -282,6 +300,19 @@ impl TraceLifecycleEvent {
     }
 }
 
+/// Non-sensitive carrier-negotiation fields attached to lifecycle records.
+#[derive(Debug)]
+pub(crate) struct TraceCarrierDetail {
+    /// Stable client classification; never a raw User-Agent.
+    pub(crate) client_class: &'static str,
+    /// Candidate associated with the lifecycle transition.
+    pub(crate) carrier: crate::config::WebCarrier,
+    /// One-based candidate attempt.
+    pub(crate) attempt: u8,
+    /// Weighted learning scores indexed by the canonical carrier order.
+    pub(crate) scores: [i16; 4],
+}
+
 /// One typed WEB lifecycle observation.
 #[derive(Debug)]
 pub(crate) struct TraceLifecycleRecord {
@@ -291,6 +322,8 @@ pub(crate) struct TraceLifecycleRecord {
     pub(crate) stream_id: Option<u32>,
     /// Closed outcome or rejection reason.
     pub(crate) reason: Option<&'static str>,
+    /// Carrier negotiation detail when this is a carrier lifecycle event.
+    pub(crate) carrier: Option<TraceCarrierDetail>,
 }
 
 /// Trace record payload variant.