fix: address review report across security, architecture, quality, tests

Implements the fixes from docs/REVIEW_REPORT.md (4-agent parallel review).
typecheck clean; 341 tests pass (16 files, +113); build:web ok; coverage
thresholds (80%) enforced in vitest.config.ts.

Critical:
- multi-device approval race: release held approval only when the last
  client detaches (closing one mirror no longer cancels another's prompt)
- unbounded session creation (DoS): Config.maxSessions cap (env MAX_SESSIONS),
  enforced in manager via the existing M4 exit(-1) path
- signal-handler leak: named SIGINT/SIGTERM/uncaughtException refs removed in close()
- terminal-session initialInput timer tracked + cleared on dispose
- tabs.addEntry null-as-cast type hole removed (build session before entry)

Should-fix:
- security-headers middleware + Origin/CSRF guard on DELETE /live-sessions[/:id]
- history.ts converted to fs/promises (async /sessions handler)
- removed dead clientDims map + blur protocol message end-to-end
- per-connection WS message rate limit (Config.maxMsgsPerSec)
- /sessions behavior kept; documented as accepted LAN risk (TECH_DOC §7)

Tests:
- new tmux / preview-grid / terminal-session (jsdom) / tabs (jsdom) suites
- extended history/config/manager/integration coverage incl. regressions

Hygiene:
- parsePositiveInt -> parseNonNegativeInt; ALLOWED_ORIGINS scheme validation
- log-injection sanitize; isLoopback handles 127.0.0.0/8 + IPv4-mapped
- operational constants moved into Config
- extracted public/preview-grid.ts (DRY launcher/manage)
- doc sweeps: ARCHITECTURE §8 runtime-handle exception, stale comments

test/history.test.ts

@@ -1,6 +1,28 @@
-import { describe, it, expect } from 'vitest'
-import { parseSessionMeta } from '../src/http/history.js'
+import { describe, it, expect, vi, beforeEach } from 'vitest'
 
+// ── mock node:fs/promises + node:os ──────────────────────────────────────────
+// Hoisted by vitest; history.ts binds to these mocks.
+const mockReaddir = vi.fn()
+const mockStat = vi.fn()
+const mockOpen = vi.fn()
+const mockHomedir = vi.fn(() => '/home/tester')
+
+vi.mock('node:fs/promises', () => ({
+  default: {
+    readdir: (...a: unknown[]) => mockReaddir(...a),
+    stat: (...a: unknown[]) => mockStat(...a),
+    open: (...a: unknown[]) => mockOpen(...a),
+  },
+}))
+
+vi.mock('node:os', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('node:os')>()
+  return { ...actual, default: { ...actual.default, homedir: () => mockHomedir() } }
+})
+
+const { parseSessionMeta, listSessions } = await import('../src/http/history.js')
+
+// ── parseSessionMeta (pure) ───────────────────────────────────────────────────
 describe('parseSessionMeta', () => {
   it('extracts cwd and the first user prompt (string content)', () => {
     const jsonl = [
@@ -31,3 +53,71 @@ describe('parseSessionMeta', () => {
     expect(parseSessionMeta('not json\n{"type":"summary"}')).toEqual({ cwd: null, preview: '' })
   })
 })
+
+// ── listSessions (fs traversal, async) ────────────────────────────────────────
+describe('listSessions', () => {
+  function mockFile(text: string) {
+    const buf = Buffer.from(text, 'utf8')
+    return {
+      read: vi.fn(async (b: Buffer, off: number, len: number) => {
+        const n = buf.copy(b, off, 0, Math.min(len, buf.length))
+        return { bytesRead: n }
+      }),
+      close: vi.fn(async () => undefined),
+    }
+  }
+
+  beforeEach(() => {
+    mockReaddir.mockReset()
+    mockStat.mockReset()
+    mockOpen.mockReset()
+    mockHomedir.mockReturnValue('/home/tester')
+  })
+
+  it('returns [] when the projects root is missing', async () => {
+    mockReaddir.mockRejectedValueOnce(new Error('ENOENT'))
+    expect(await listSessions()).toEqual([])
+  })
+
+  it('lists .jsonl sessions newest-first with parsed cwd/preview/project', async () => {
+    mockReaddir
+      .mockResolvedValueOnce(['projA']) // root
+      .mockResolvedValueOnce(['old.jsonl', 'new.jsonl', 'ignore.txt']) // projA
+    mockStat.mockImplementation(async (p: string) => ({
+      mtimeMs: p.endsWith('new.jsonl') ? 2000 : 1000,
+    }))
+    mockOpen.mockImplementation(async (p: string) =>
+      p.endsWith('new.jsonl')
+        ? mockFile(JSON.stringify({ type: 'user', cwd: '/work/newdir', message: { role: 'user', content: 'newest task' } }))
+        : mockFile(JSON.stringify({ type: 'user', cwd: '/work/olddir', message: { role: 'user', content: 'older task' } })),
+    )
+
+    const out = await listSessions()
+    expect(out.map((s) => s.id)).toEqual(['new', 'old']) // newest first
+    expect(out[0]).toMatchObject({ id: 'new', cwd: '/work/newdir', project: 'newdir', preview: 'newest task' })
+    // .txt is skipped
+    expect(out).toHaveLength(2)
+  })
+
+  it('skips a project subdir that cannot be read', async () => {
+    mockReaddir
+      .mockResolvedValueOnce(['good', 'bad'])
+      .mockResolvedValueOnce(['s.jsonl']) // good
+      .mockRejectedValueOnce(new Error('EACCES')) // bad
+    mockStat.mockResolvedValue({ mtimeMs: 1000 })
+    mockOpen.mockResolvedValue(mockFile(JSON.stringify({ type: 'user', cwd: '/g', message: { role: 'user', content: 'hi' } })))
+
+    const out = await listSessions()
+    expect(out).toHaveLength(1)
+    expect(out[0]!.id).toBe('s')
+  })
+
+  it('respects the limit', async () => {
+    mockReaddir.mockResolvedValueOnce(['p']).mockResolvedValueOnce(['a.jsonl', 'b.jsonl', 'c.jsonl'])
+    mockStat.mockImplementation(async (p: string) => ({ mtimeMs: p.charCodeAt(p.length - 7) }))
+    mockOpen.mockResolvedValue(mockFile(JSON.stringify({ type: 'user', cwd: '/p', message: { role: 'user', content: 'x' } })))
+
+    const out = await listSessions(2)
+    expect(out).toHaveLength(2)
+  })
+})