perf: v2.5.10 — ready for 10+ concurrent users, leaner locally

Measured on a copy of a real 1.2 GB / 253K-event database, 10 simulated
browsers + 10 hooks/s for 90 s: event-loop delay p99 1239 ms → 32 ms (max
2.0 s → 94 ms), 266 failed requests → 0, 74 → 111 requests/s served, server
RSS 633 → 346 MB. Entry bundle 975 KB raw → 394 KB (106 KB brotli).

Server
- /api/analytics: the events-table scans run in the read worker
  (scoped-stats eventAggregates, read-pool job analyticsEvents); runRead takes
  maxAgeMs — analytics 10 s, /api/workflows 30 s — keyed by the args
- /api/workflows/skill-usage: +event_type and a tool_name range instead of
  LIKE, so it uses idx_events_tool (784 ms → a few ms)
- idx_events_session_type_tool (session_id, event_type, tool_name,
  created_at) replaces idx_events_session_type: covering reads for session
  stats, the hook dedupes and the import resume point (1.2 s → 20 ms); 64 MB
  cache_size and 256 MB mmap_size on both connections
- WAL: the server sets wal_autocheckpoint = 0 and checkpoints PASSIVE every
  DASHBOARD_WAL_CHECKPOINT_MS (5 s) from the read worker's own writable
  connection; a failed checkpoint restores the automatic one (hook COMMIT p95
  109 ms → 15 ms at 100 hooks/s)
- tmux: one list-sessions answers a whole GET /api/lanes and the heal beat
  (liveSessions), shared for 1 s and cleared by this process's new/kill —
  GET /api/run's sync spawns had blocked 60 s of a 90 s run; the heal beat
  skips tmux when nothing runs; attach options chained into 2 spawns
- hooks: TurnDuration/APIError deduped against one read per hook instead of a
  query per transcript entry (23 ms/hook on a 763-turn session); one lane
  scan per hook; hourly upserts skip rows that did not grow; frames are sent
  after the transaction commits (and after the pane binding); new_event
  carries its row id; a split pane's (slot 1–9) hooks no longer rebind the
  lane's session_id
- watchdog liveness probe runs ps asynchronously; transcript newline scan via
  indexOf; startup subagent backfill fingerprints the files it already checked
- pty attach: backpressure (pause past 1 MB unsent, resume under 256 KB)
- static: hashed assets served from their pre-compressed .br/.gz sibling

Client
- hidden tabs neither refetch on WS events nor poll (useLiveRefresh, panes,
  lane cards, git header, changes panel, settings); no per-tab hourly
  /updates/check (the server already checks)
- refetch storms throttled (workspace tree/session list 3 s, /api/run only on
  a run-key change, notification pane lookup only when shown); WS reconnect
  jitter; terminal retry backoff 1.5 → 30 s, stops on 1008
- heavier throttles for aggregates (15 s) and detail views; Monitor keepIfSame;
  GET in-flight dedupe in request()
- lazy Dashboard/History, xterm (with the first terminal), lane modals, Sagi
  (only while enabled); only the active locale loads; Workspace chunk
  prefetched on a /workspace deep link
- Sagi: no work while disabled, pupil via CSS variables, memo avatar
- build: .br/.gz siblings, sourcemap hidden; service worker no longer caches
  /assets/ (cache v3 drops the old one)

Tests: scripts/test-server.js drops the GIT_DIR-family variables a hook
exports, so a suite run from a linked worktree's pre-commit can no longer
commit into the real repository or set core.bare.

Docs: ARCHITECTURE, DATABASE, API, DEPLOYMENT, client README,
docs/plans/perf/README.md (audit, checklist, results).

server/routes/lanes.js

@@ -28,6 +28,7 @@ const laneFeatures = require("../lib/lane-features");
 const proofLib = require("../lib/proof");
 const { broadcast } = require("../websocket");
 const runs = require("../lib/pty-run");
+const tmux = require("../lib/tmux");
 const { resumeProxy } = require("../lib/proxy-apply");
 const { sameOriginGuard } = require("./run");
 const { writeLaneFile } = require("../lib/lane-file-write");
@@ -115,10 +116,14 @@ function lastEventAge(lane) {
  * it, exactly like the old push-based handler did, just pulled instead of
  * pushed.
  */
-function healRunId(lane) {
+function healRunId(lane, live = null) {
   if (!lane.run_id) return lane;
-  const run = runs.getRun(lane.run_id);
-  if (run && run.status === "running") return lane;
+  if (live) {
+    if (live.has(lane.run_id)) return lane;
+  } else {
+    const run = runs.getRun(lane.run_id);
+    if (run && run.status === "running") return lane;
+  }
   lanesLib.updateLane(lane.id, { run_id: null, status: "idle" });
   broadcastLane(lane.id);
   return lanesLib.getLane(lane.id);
@@ -128,10 +133,11 @@ function healRunId(lane) {
  * Heal every lane at once. A claude pane that exits fires a hook, which
  * broadcasts the lane and so re-reads it; a codex or antigravity pane fires
  * nothing, so without this sweep its lane read "running" until something
- * else happened to fetch it.
+ * else happened to fetch it. `live` (a `tmux.liveSessions()` set) answers
+ * every lane from one tmux call instead of a has-session per lane.
  */
-function healAllRunIds() {
-  for (const lane of lanesLib.listLanes()) if (lane.run_id) healRunId(lane);
+function healAllRunIds(live = null) {
+  for (const lane of lanesLib.listLanes()) if (lane.run_id) healRunId(lane, live);
 }
 
 /**
@@ -171,8 +177,8 @@ function broadcastForeignLaneChanges() {
   return out;
 }
 
-function payload(lane) {
-  const healed = healRunId(lane);
+function payload(lane, live = null) {
+  const healed = healRunId(lane, live);
   return lanesLib.lanePayload(healed, lastEventAge(healed));
 }
 
@@ -195,7 +201,11 @@ function broadcastLane(id) {
 }
 
 router.get("/", (_req, res) => {
-  const lanes = lanesLib.listLanes().map(payload);
+  const rows = lanesLib.listLanes();
+  // ONE list-sessions answers every lane's run, instead of a synchronous
+  // has-session per lane (null when tmux could not be asked: per-lane then).
+  const live = rows.some((l) => l.run_id) ? tmux.liveSessions() : null;
+  const lanes = rows.map((l) => payload(l, live));
   res.json({
     lanes,
     counts: {