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/lib/session-liveness.js

@@ -16,7 +16,7 @@
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
 
-const { execFileSync } = require("node:child_process");
+const { execFile, execFileSync } = require("node:child_process");
 const fs = require("node:fs");
 const path = require("node:path");
 const { isInsideContainer } = require("../../scripts/install-hooks");
@@ -63,21 +63,45 @@ function probeDisabledByEnv() {
  * with an empty set genuinely means no claude process is running.
  */
 function probeLiveCwds() {
-  if (probeDisabledByEnv()) return UNAVAILABLE();
-  if (process.platform === "win32") return UNAVAILABLE();
-  if (isInsideContainer()) return UNAVAILABLE();
-
+  if (probeBlocked()) return UNAVAILABLE();
   let psOut;
   try {
-    psOut = execImpl("ps", ["-Ao", "pid=,args="], {
-      encoding: "utf8",
-      timeout: 5_000,
-      maxBuffer: 16 * 1024 * 1024,
-    });
+    psOut = execImpl("ps", PS_ARGS, PS_OPTS);
   } catch {
     return UNAVAILABLE();
   }
+  return cwdsFromPs(psOut);
+}
 
+/**
+ * `probeLiveCwds` with `ps` run asynchronously — what the watchdog's 15 s
+ * beat uses, so the spawn (24–300 ms inside a large server process) never
+ * blocks the event loop. Same answer shape; resolves, never rejects.
+ *
+ * @returns {Promise<{ available: boolean, cwds: Set<string> }>}
+ */
+function probeLiveCwdsAsync() {
+  if (probeBlocked()) return Promise.resolve(UNAVAILABLE());
+  return new Promise((resolve) => {
+    execFile("ps", PS_ARGS, PS_OPTS, (err, out) => {
+      try {
+        resolve(err ? UNAVAILABLE() : cwdsFromPs(out));
+      } catch {
+        resolve(UNAVAILABLE());
+      }
+    });
+  });
+}
+
+const PS_ARGS = ["-Ao", "pid=,args="];
+const PS_OPTS = { encoding: "utf8", timeout: 5_000, maxBuffer: 16 * 1024 * 1024 };
+
+function probeBlocked() {
+  return probeDisabledByEnv() || process.platform === "win32" || isInsideContainer();
+}
+
+/** The cwds of the `claude` processes in a `ps -Ao pid=,args=` listing. */
+function cwdsFromPs(psOut) {
   const pids = [];
   for (const line of psOut.split("\n")) {
     const m = line.match(/^\s*(\d+)\s+(.*)$/);
@@ -120,4 +144,4 @@ function probeLiveCwds() {
   return { available: true, cwds };
 }
 
-module.exports = { probeLiveCwds, isClaudeCommand, __setExecImpl };
+module.exports = { probeLiveCwds, probeLiveCwdsAsync, isClaudeCommand, __setExecImpl };