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).

client/src/components/run/__tests__/TerminalView.test.tsx

@@ -3,13 +3,14 @@
  * @description Tests for the xterm.js-backed terminal view: verifies it opens
  * a WS connection to the right URL, writes incoming binary frames to the
  * mocked terminal, forwards typed input as outgoing binary frames, and
- * re-attaches after the socket drops (server restart) but not after `exit`,
+ * re-attaches after the socket drops (server restart) with backoff, but not
+ * after `exit` or a policy close,
  * and recolours live on a dark-theme change without re-attaching.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
-import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { describe, it, expect, vi, beforeAll, beforeEach, afterEach } from "vitest";
 import { render, cleanup, act, fireEvent, screen, waitFor } from "@testing-library/react";
-import { TerminalView } from "../TerminalView";
+import { TerminalView, loadXterm } from "../TerminalView";
 import { pasteToRun } from "../../../lib/panePaste";
 
 const writeMock = vi.fn();
@@ -87,7 +88,7 @@ class MockWebSocket {
   sent: unknown[] = [];
   onopen: (() => void) | null = null;
   onmessage: ((e: { data: unknown }) => void) | null = null;
-  onclose: (() => void) | null = null;
+  onclose: ((e?: { code: number }) => void) | null = null;
   readyState = 1; // OPEN — the component only sends on an open socket
   static OPEN = 1;
   constructor(url: string) {
@@ -105,6 +106,9 @@ class MockWebSocket {
 global.WebSocket = MockWebSocket;
 
 describe("TerminalView", () => {
+  // xterm is a lazy chunk; once loaded every terminal sets up synchronously.
+  beforeAll(() => loadXterm());
+
   beforeEach(() => {
     termState.modes.mouseTrackingMode = "none";
     termState.buffer.active.type = "alternate";
@@ -388,6 +392,23 @@ describe("TerminalView", () => {
     vi.useRealTimers();
   });
 
+  it("backs off between failed re-attaches, and stops on a policy close (1008)", () => {
+    vi.useFakeTimers();
+    render(<TerminalView runId="agenthub-lane-1" wsBaseUrl="ws://localhost:4820" />);
+    MockWebSocket.instances[0]!.close();
+    vi.advanceTimersByTime(1600);
+    expect(MockWebSocket.instances).toHaveLength(2);
+    MockWebSocket.instances[1]!.close(); // failed again: now 3 s
+    vi.advanceTimersByTime(1600);
+    expect(MockWebSocket.instances).toHaveLength(2);
+    vi.advanceTimersByTime(1500);
+    expect(MockWebSocket.instances).toHaveLength(3);
+    act(() => MockWebSocket.instances[2]!.onclose?.({ code: 1008 }));
+    vi.advanceTimersByTime(60_000);
+    expect(MockWebSocket.instances).toHaveLength(3);
+    vi.useRealTimers();
+  });
+
   it("does not re-attach once the server reported the pane exited", () => {
     vi.useFakeTimers();
     render(<TerminalView runId="agenthub-lane-1" wsBaseUrl="ws://localhost:4820" />);