docs(tasks): review-001 ws-session-limits remediation complete

tasks/websocket/review-001-ws-session-limits.md

@@ -1,7 +1,7 @@
 ---
 id: review-001-ws-session-limits
 name: WS session lifecycle — idle timeout, shutdown, teardown, caps (WS-01, WS-07..WS-10)
-status: pending
+status: completed
 depends_on: [review-001-ws-eof-signal]
 scope: narrow
 risk: medium
@@ -42,12 +42,12 @@ Review 001 WS subsystem lifecycle/staleness findings over
 
 ## Acceptance Criteria
 
-- [ ] Idle timeout bounds a dribble stall (test: dribbling peer's channels fail/bound rather than hang forever)
-- [ ] `shutdown()` causes a WS Close frame to the peer (test)
-- [ ] `_pumps` retained; `abort()` reachable on the server path
-- [ ] Session concurrency cap configurable in `HttpAdapter`; enforced (test)
-- [ ] Detached-task lifetime semantics documented (WS-10)
-- [ ] `cargo test` and `cargo clippy --all-targets -- -D warnings` pass
+- [x] Idle timeout bounds a dribble stall (test: dribbling peer's channels fail/bound rather than hang forever)
+- [x] `shutdown()` causes a WS Close frame to the peer (test)
+- [x] `_pumps` retained; `abort()` reachable on the server path
+- [x] Session concurrency cap configurable in `HttpAdapter`; enforced (test)
+- [x] Detached-task lifetime semantics documented (WS-10)
+- [x] `cargo test` and `cargo clippy --all-targets -- -D warnings` pass
 
 ## References
 
@@ -61,4 +61,86 @@ Review 001 WS subsystem lifecycle/staleness findings over
 
 ## Summary
 
-> Filled on completion.
+All five lifecycle findings fixed in `src/websocket/` (+ `server/`
+builder plumbing, one test-side touchpoint):
+
+- **WS-07** (`websocket/byte_adapter.rs`): `poll_shutdown` dropped a
+  *fresh clone* of `write_tx` — the pump-side channel never closed, so
+  the write pump's trailing `ws_sink.close()` (the WS Close frame at
+  shutdown) never ran. Mechanics of the fix: `WsByteStream.write_tx`
+  became `Option<Sender<WriteMsg>>`; `poll_shutdown` **takes** the held
+  sender (no clone). Both senders must be gone for the queue to close —
+  the read pump holds the other clone until its loop ends (peer close /
+  read error / idle timeout), which is the documented close sequencing.
+  The write pump then drains the queued bytes and closes the sink.
+  (Test: `tungstenite_shutdown_closes_the_write_sink_toward_the_peer`.)
+- **WS-08** (`websocket/upgrade.rs` + `server/state.rs`,
+  `server/adapter.rs`): retention point is a **shared `WsSessions`
+  registry** — `Arc` of a `parking_lot` map (`u64 → Arc<WsPumps>`)
+  carried in `RouterState` and lifted into the handler via the new
+  `SessionState` `FromRef` substate; a `WsSessions` request extension
+  overrides the state instance (mirrors the SRV-10 `ChannelsPolicy`
+  seam; extending alkcall's `ChannelLifecyclePolicy` itself was not
+  possible — the trait is owned by the call crate). The session task
+  registers its pumps through a self-removing guard, so an entry
+  exists exactly for the session's lifetime; `WsSessions::abort()`
+  force-ends the pump tasks of every live session (eviction lever) and
+  `HttpAdapter::ws_sessions()` hands the shared instance to the
+  assembly layer. (Test:
+  `ws_sessions_registry_tracks_and_aborts_live_sessions`.)
+- **WS-09** (`websocket/upgrade.rs`, `server/adapter.rs`): a
+  `tokio::sync::Semaphore` cap on concurrent WS sessions, acquired
+  post-auth / pre-upgrade in `ws_upgrade_handler` with
+  `try_acquire_owned`; exhausted → **503 Service Unavailable**. The
+  permit moves into the upgrade closure and is held for the session's
+  lifetime (ended sessions free their slot). Configurable via
+  `HttpAdapter::with_ws_max_sessions(usize)`; default
+  [`DEFAULT_WS_MAX_SESSIONS`] = **64** (documented const). One
+  semaphore per adapter, built once (an earlier per-request
+  construction bug would have made the cap a no-op — caught by the
+  acceptance test). (Tests: `session_cap_rejects_over_limit_with_503_and_frees_slots_on_end`.)
+- **WS-01** (`websocket/byte_adapter.rs`: `run_read_pump`; knob in
+  `upgrade.rs`/`server/adapter.rs`): the read pump's next-message await
+  is wrapped in `tokio::time::timeout` **inside** the loop (the
+  consolidation shape untouched — `on_end` still fires exactly once
+  after the loop, so the from_wss watch+monitor+sweep machinery is
+  unchanged). Staleness sends the **1001 GoingAway** close
+  ([`WS_GOING_AWAY`]) to the peer and ends the read loop → EOF → the
+  demux clears channels and fails pendings as a normal connection end.
+  The window resets per inbound WS message (a dribble of messages
+  within the window never trips; only a true stall does). Knob:
+  `HttpAdapter::with_ws_idle_timeout(Option<Duration>)` (`None`
+  disables); default [`DEFAULT_WS_IDLE_TIMEOUT`] = **60 s**. The split
+  functions gained `_idle` variants
+  (`split_ws_to_bytes_idle`/`split_tungstenite_to_bytes_idle`); the
+  old names keep the default. (Tests:
+  `idle_read_timeout_closes_a_stalled_connection_with_goingaway` —
+  stalled peer gets the 1001 + EOF signal within the knob;
+  `idle_read_timeout_resets_on_traffic` — a dribble of one message per
+  half-window keeps the connection alive across many windows.)
+- **WS-10** (`websocket/upgrade.rs`, docs-only): new module-doc section
+  "Detached task lifetime semantics" — the pump and channel-0
+  dispatcher tasks are detached by design and outlive a failed session
+  task; they self-heal (each ends when its stream half closes), the
+  leak window is bounded by peer behavior and (when configured) the
+  WS-01 idle timeout, and every session's pumps stay force-evictable
+  via the WS-08 registry.
+
+Also: `src/adapters/to_mcp.rs` test
+`search_honors_query_substring_filter` asserted a hard-coded operation
+order over a HashMap-derived upstream list (pre-existing flake on
+main, fails ~1/3 in isolation, unrelated to WS); made the assert
+order-independent (sorted).
+
+Knob defaults: session cap 64 (`DEFAULT_WS_MAX_SESSIONS`), idle-read
+timeout 60 s (`DEFAULT_WS_IDLE_TIMEOUT`). Pumps-handle retention: the
+`WsSessions` registry in `RouterState` (`HttpAdapter::ws_sessions()`),
+override via the `WsSessions` request extension. WS-07 mechanics: the
+held `write_tx` is taken (Option) at shutdown — no clone — so the
+pump-side close (drain + `ws_sink.close()` → WS Close frame) runs once
+the read pump's sentinel clone also drops.
+
+Verification: `cargo test` 300 passed; `cargo test --all-features` all
+green (371 lib + ws/from_mcp/full-surface suites); `cargo clippy
+--all-targets -- -D warnings` and `cargo clippy --all-features
+--all-targets -- -D warnings` clean; `cargo fmt --check` clean.