/**
 * T13 tests — session/manager.ts (session table lifecycle).
 *
 * ARCHITECTURE §3.5 + the cross-validated fixes:
 *  - M3: reapIdle uses now - max(detachedAt, lastOutputAt) > idleTtlMs
 *        (not just detachedAt, so active sessions with recent output are not reaped).
 *  - M4: createSession throwing propagates out of handleAttach (not swallowed).
 *  - L1: attach hitting an already-exited session → replay buffer + resend exit + remove.
 *  - L2: the onExit callback injected into createSession removes the session from the table.
 *
 * node-pty is mocked so spawn returns a MockIPty — no real PTY/shell is started.
 */

import { describe, it, expect, beforeEach, vi } from 'vitest';

import type {
  Config,
  Dims,
  NotifyService,
  Session,
  StatusTelemetry,
  WebSocketLike,
} from '../src/types.js';
import { WS_OPEN } from '../src/types.js';
import { createMockPty, type MockIPty } from './helpers/mock-pty.js';

// ── node-pty mock ───────────────────────────────────────────────────────────
// All createSession calls ultimately call spawn; we intercept at the node-pty
// boundary so the session module works exactly as in production, but no real
// shell is ever spawned.

let nextPty: MockIPty = createMockPty();
let spawnShouldThrow: Error | null = null;

vi.mock('node-pty', () => ({
  spawn: (_file: string, _args: string[], _options: unknown) => {
    if (spawnShouldThrow) throw spawnShouldThrow;
    return nextPty;
  },
}));

// Import AFTER vi.mock so the module under test binds to the mocked spawn.
const { createSessionManager } = await import('../src/session/manager.js');

// ── Helpers ──────────────────────────────────────────────────────────────────

const CFG: Config = {
  port: 3000,
  bindHost: '0.0.0.0',
  shellPath: '/bin/zsh',
  homeDir: '/home/tester',
  idleTtlMs: 10_000, // 10 s for easy arithmetic in tests
  scrollbackBytes: 2 * 1024 * 1024,
  maxPayloadBytes: 1024 * 1024,
  wsPath: '/term',
  maxSessions: 50,
  maxMsgsPerSec: 2000,
  permTimeoutMs: 300_000,
  reapIntervalMs: 60_000,
  previewBytes: 24 * 1024,
  useTmux: false,
  allowedOrigins: [],
  // v0.6 project manager
  projectRoots: ['/home/tester'],
  projectScanDepth: 4,
  projectScanTtlMs: 10_000,
  projectDirtyCheck: true,
  editorCmd: 'code',
  // v0.7 Walk-away Workbench
  vapidPublicKey: undefined,
  vapidPrivateKey: undefined,
  vapidSubject: undefined,
  pushStorePath: '/home/tester/.web-terminal-push-subs.json',
  pushMaxSubs: 50,
  notifyDone: true,
  notifyDnd: false,
  decisionTokenTtlMs: 300_000,
  timelineMax: 200,
  timelineEnabled: true,
  stuckTtlMs: 10_000, // 10 s for easy arithmetic in tests
  stuckAlert: true,
  diffTimeoutMs: 2000,
  diffMaxBytes: 2 * 1024 * 1024,
  diffMaxFiles: 300,
  statuslineTtlMs: 30_000,
  worktreeEnabled: true,
  worktreeRoot: undefined,
  worktreeTimeoutMs: 10_000,
  defaultPermissionMode: 'default',
  allowAutoMode: false,
  // W2 inject queue
  queueEnabled: true,
  queueMaxItems: 10,
  queueItemMaxBytes: 4096,
  queueSettleMs: 1500,
};

const DIMS: Dims = { cols: 80, rows: 24 };

/** A telemetry sample for B2 tests. */
function makeTelemetry(at = 1_000): StatusTelemetry {
  return { contextUsedPct: 42, costUsd: 1.23, model: 'sonnet', at };
}

/** A mock NotifyService (DI) recording every notify(session, cls, token?) call. */
function createMockNotify() {
  const notify = vi.fn(async (_session: Session, _cls: string, _token?: string) => {});
  const service: NotifyService = {
    isEnabled: () => true,
    notify,
  };
  return { service, notify };
}

interface MockWs extends WebSocketLike {
  readyState: number;
  sent: string[];
  closed: boolean;
}

function createMockWs(readyState: number = WS_OPEN): MockWs {
  const sent: string[] = [];
  return {
    readyState,
    sent,
    closed: false,
    send(data: string) {
      sent.push(data);
    },
    close() {
      this.closed = true;
      this.readyState = 3; // CLOSED
    },
  };
}

function parseSent(ws: MockWs) {
  return ws.sent.map((s) => JSON.parse(s));
}

beforeEach(() => {
  nextPty = createMockPty();
  spawnShouldThrow = null;
});

// ── handleAttach: null sessionId → new session ────────────────────────────────
describe('handleAttach — null sessionId', () => {
  it('creates a new session and returns it', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const session = mgr.handleAttach(ws, null, DIMS, 1_000);

    expect(session).toBeDefined();
    expect(session.meta.id).toBeTruthy();
    expect(session.clients.has(ws)).toBe(true);
  });

  it('stores the session so get() returns it', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const session = mgr.handleAttach(ws, null, DIMS, 1_000);

    expect(mgr.get(session.meta.id)).toBe(session);
  });

  it('propagates spawn failure without swallowing it (M4)', () => {
    spawnShouldThrow = new Error('spawn failed: /no/such/shell ENOENT');
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();

    expect(() => mgr.handleAttach(ws, null, DIMS, 1_000)).toThrow(/spawn failed/);
  });
});

// ── handleAttach: hit live session ────────────────────────────────────────────
describe('handleAttach — hit live session', () => {
  it('JOINS the new ws and returns the same session (multi-device share)', () => {
    const mgr = createSessionManager(CFG);
    const ws1 = createMockWs();
    const session = mgr.handleAttach(ws1, null, DIMS, 1_000);
    const id = session.meta.id;

    const ws2 = createMockWs();
    const session2 = mgr.handleAttach(ws2, id, DIMS, 2_000);

    expect(session2).toBe(session);
    // Both clients share the session now.
    expect(session.clients.has(ws1)).toBe(true);
    expect(session.clients.has(ws2)).toBe(true);
  });

  it('does NOT kick the previously attached ws (v0.4 sharing)', () => {
    const mgr = createSessionManager(CFG);
    const ws1 = createMockWs();
    const session = mgr.handleAttach(ws1, null, DIMS, 1_000);
    const id = session.meta.id;

    const ws2 = createMockWs();
    mgr.handleAttach(ws2, id, DIMS, 2_000);

    // The old ws must stay open — devices mirror the session.
    expect(ws1.closed).toBe(false);
    expect(session.clients.size).toBe(2);
  });

  it('broadcasts live output to ALL joined clients', () => {
    const mgr = createSessionManager(CFG);
    const ws1 = createMockWs();
    const session = mgr.handleAttach(ws1, null, DIMS, 1_000);
    const ws2 = createMockWs();
    mgr.handleAttach(ws2, session.meta.id, DIMS, 2_000);
    ws1.sent.length = 0;
    ws2.sent.length = 0;

    (session.pty as MockIPty).emitData('to everyone');

    expect(parseSent(ws1).some((m) => m.type === 'output' && m.data === 'to everyone')).toBe(true);
    expect(parseSent(ws2).some((m) => m.type === 'output' && m.data === 'to everyone')).toBe(true);
  });

  it('replays the buffer to the new ws', () => {
    const mgr = createSessionManager(CFG);
    const ws1 = createMockWs();
    const session = mgr.handleAttach(ws1, null, DIMS, 1_000);
    const id = session.meta.id;

    // Produce some output while ws1 is attached.
    (session.pty as MockIPty).emitData('hello world');

    const ws2 = createMockWs();
    mgr.handleAttach(ws2, id, DIMS, 2_000);

    const msgs = parseSent(ws2);
    const outputMsgs = msgs.filter((m) => m.type === 'output');
    expect(outputMsgs.some((m: { data: string }) => m.data.includes('hello world'))).toBe(true);
  });
});

// ── handleAttach: hit already-exited session (L1) ─────────────────────────────
describe('handleAttach — hit already-exited session (L1)', () => {
  it('sends the buffer snapshot to the new ws', () => {
    const mgr = createSessionManager(CFG);
    const ws1 = createMockWs();
    const session = mgr.handleAttach(ws1, null, DIMS, 1_000);
    const id = session.meta.id;

    // Build some output, then detach ws1, then simulate PTY exit.
    (session.pty as MockIPty).emitData('last output before exit');
    mgr.handleAttach(createMockWs(), id, DIMS, 2_000); // re-attach so we can detach
    // Force detach by patching directly (simulates WS close event).
    session.clients.clear();
    session.detachedAt = 3_000;

    // Now PTY exits while detached — session preserved (L1).
    (session.pty as MockIPty).emitExit(0);

    // session.exitedAt is set, session still in table because onExit in detach
    // scenario keeps session (manager's onExit callback removes from table only if
    // invoked — but per L2, after exit while attached ws exists the callback removes,
    // while L1 says detach-then-exit: we must keep for replay).
    // Actually per ARCHITECTURE: the injected onExit IS called by session.ts after exit.
    // But the L1 scenario means: exitedAt!=null, session is in table until re-attach.
    // We re-insert it manually to simulate the correct state from ARCHITECTURE §4.4:
    // "session is preserved (buffer + exitedAt)" waiting for re-attach.
    // The key thing to test is that when a NEW ws comes with this session's id,
    // the manager replays the buffer + sends exit + removes from table.

    // For this test: we need the session to still be in the map with exitedAt set.
    // The manager's injected onExit should NOT remove from table in this case —
    // But wait: per ARCHITECTURE §3.5 L2: "PTY 退出: injected onExit → 从表删除"
    // And L1: "detach后exit → 保留buffer+exitedAt, 等用户回来attach"
    // These seem contradictory. Let me re-read:
    //
    // ARCHITECTURE §3.5 constraint: "PTY 退出: createSession 内部 onExit → 置 exitedAt →
    //   有 ws 则发 exit → 调 manager 注入的回调从表移除 (L2)"
    // ARCHITECTURE §3.5 L1: "detach 后才退出(无 ws 可通知, L1): 不立即丢弃会话, 保留
    //   buffer + exitedAt, 等用户带旧 id 回来 attach 时回放 + 补发 exit"
    //
    // Resolution: L2 says "从表移除" — but L1 says "不立即丢弃". So L2 applies when
    // attachedWs is NOT null (ws is attached), and L1 applies when detached.
    // The manager's injected onExit callback should:
    //   - Only remove from table if attachedWs != null at exit time (ws was attached)
    //   - Keep in table if detached at exit time (for L1 replay on reconnect)
    //
    // But PLAN.md T13 Steps says: "注入给 createSession 的 onExit: 从会话表删除该会话 (L2)"
    // And the task prompt says: "L2: onExit 从会话表删除"
    // And also: "命中已退出会话(exitedAt!=null) → 回放+补发exit后从表移除(L1)"
    //
    // So the behavior is:
    //  - When PTY exits with ws attached: onExit removes from table immediately (L2).
    //  - When PTY exits while detached (L1): onExit does NOT remove; session stays.
    //    The session is removed when the next attach hits it and sees exitedAt!=null.
    //
    // This means the manager's onExit callback must check attachedWs: if null, keep.
    // If ws attached, remove.
    //
    // Actually re-reading ARCHITECTURE §3.5 more carefully:
    // The constraint says: "PTY 退出: session 内部 onExit → 置 exitedAt → 有 ws 则发 exit
    //   → 调 manager 注入的回调从表移除 (L2: session 不持有 manager, 退出事件靠注入回调跨层冒泡)"
    //
    // This says "调 manager 注入的回调从表移除" — it calls the callback and removes.
    // But L1 says "不立即丢弃". These are the same callback situation.
    //
    // Looking at PLAN T13 instruction: "注入给 createSession 的 onExit: 从会话表删除该会话 (L2)"
    // And the task prompt: "命中已退出 → 回放+补发exit+移除 → 从表移除(L1)"
    //
    // The reconciliation: L2's callback ALWAYS removes the session from the table when
    // called. L1 means: when the session exits while detached, the session stays in the
    // table BECAUSE the onExit in the detach case should NOT remove it immediately.
    //
    // Wait, but the task prompt says "注入给 createSession 的 onExit: 从会话表删除该会话 (L2)"
    // unconditionally. And L1 says "保留 buffer + exitedAt".
    //
    // The only way to reconcile: the onExit callback should NOT remove when detached.
    // The callback should check session.attachedWs (which is null when detached):
    //   if (session.attachedWs !== null) → remove from table (session was live)
    //   if (session.attachedWs === null) → keep in table (for L1 replay)
    //
    // This matches ARCHITECTURE §4.4: "[在 detach 状态下退出] pty.onExit → 置 exitedAt/exitCode
    //   → attachedWs 为 null, exit 暂不投递 → 会话保留(buffer + exitedAt)"
    // And the session.ts onExit flow: sets exitedAt, sends exit if ws, calls manager onExit.
    //
    // So the manager's onExit MUST only remove when ws was attached. When detached,
    // it should keep the session for L1 replay.
    //
    // CONCLUSION: The injected onExit callback in the manager checks session.attachedWs:
    //   - non-null → ws existed when exit fired → remove from table (L2)
    //   - null    → detached-then-exit → keep in table for L1 replay

    // At this point, session.exitedAt should be set, and session should still be in table.
    expect(session.exitedAt).not.toBeNull();

    // Now a new ws comes back with the same session id:
    const ws2 = createMockWs();
    // Need to re-add session to map manually IF the onExit removed it.
    // Let's just test the flow by checking what actually happens:
    const result = mgr.handleAttach(ws2, id, DIMS, 5_000);

    // The manager should have replayed the buffer to ws2.
    const msgs = parseSent(ws2);
    const outputMsgs = msgs.filter((m: { type: string }) => m.type === 'output');
    expect(outputMsgs.some((m: { data: string }) => m.data.includes('last output before exit'))).toBe(true);
  });

  it('sends exit message to the new ws after replay (L1)', () => {
    const mgr = createSessionManager(CFG);
    const ws1 = createMockWs();
    const session = mgr.handleAttach(ws1, null, DIMS, 1_000);
    const id = session.meta.id;

    // Detach by simulating WS close.
    session.clients.clear();
    session.detachedAt = 2_000;

    // PTY exits while detached.
    (session.pty as MockIPty).emitExit(42);

    expect(session.exitedAt).not.toBeNull();
    expect(session.exitCode).toBe(42);

    // New ws comes back.
    const ws2 = createMockWs();
    mgr.handleAttach(ws2, id, DIMS, 5_000);

    const msgs = parseSent(ws2);
    const exitMsgs = msgs.filter((m: { type: string }) => m.type === 'exit');
    expect(exitMsgs).toHaveLength(1);
    expect(exitMsgs[0]).toMatchObject({ type: 'exit', code: 42 });
  });

  it('removes the exited session from the table after replay (L1)', () => {
    const mgr = createSessionManager(CFG);
    const ws1 = createMockWs();
    const session = mgr.handleAttach(ws1, null, DIMS, 1_000);
    const id = session.meta.id;

    // Detach and exit.
    session.clients.clear();
    session.detachedAt = 2_000;
    (session.pty as MockIPty).emitExit(0);

    // Reconnect triggers L1 replay + removal.
    const ws2 = createMockWs();
    mgr.handleAttach(ws2, id, DIMS, 5_000);

    // Session must be gone from the table now.
    expect(mgr.get(id)).toBeUndefined();
  });
});

// ── handleAttach: session not found → new session ─────────────────────────────
describe('handleAttach — session not found', () => {
  it('creates a new session when the given id does not exist', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();

    const unknownId = '00000000-0000-4000-8000-000000000000';
    const session = mgr.handleAttach(ws, unknownId, DIMS, 1_000);

    expect(session).toBeDefined();
    // The returned session has a NEW id (not the bogus one).
    expect(session.meta.id).not.toBe(unknownId);
    expect(session.clients.has(ws)).toBe(true);
  });

  it('the newly created session is stored in the table', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const unknownId = '00000000-0000-4000-8000-000000000001';
    const session = mgr.handleAttach(ws, unknownId, DIMS, 1_000);

    expect(mgr.get(session.meta.id)).toBe(session);
    // Old unknown id is NOT stored.
    expect(mgr.get(unknownId)).toBeUndefined();
  });
});

// ── get ───────────────────────────────────────────────────────────────────────
describe('get', () => {
  it('returns undefined for unknown ids', () => {
    const mgr = createSessionManager(CFG);
    expect(mgr.get('00000000-0000-4000-8000-000000000002')).toBeUndefined();
  });

  it('returns the session for a known id', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const session = mgr.handleAttach(ws, null, DIMS, 1_000);
    expect(mgr.get(session.meta.id)).toBe(session);
  });
});

// ── reapIdle (M3) ─────────────────────────────────────────────────────────────
describe('reapIdle (M3)', () => {
  it('does not reap a session that is still attached', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const session = mgr.handleAttach(ws, null, DIMS, 1_000);
    // Not detached, so detachedAt = null → not eligible.

    const reaped = mgr.reapIdle(1_000 + CFG.idleTtlMs + 1);
    expect(reaped).toBe(0);
    expect(mgr.get(session.meta.id)).toBeDefined();
  });

  it('does not reap a detached session that received output recently (M3)', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const session = mgr.handleAttach(ws, null, DIMS, 1_000);
    const id = session.meta.id;

    // Detach at t=2000.
    session.clients.clear();
    session.detachedAt = 2_000;

    // Output arrives at t=5000 (AFTER detach) — refresh lastOutputAt.
    (session.pty as MockIPty).emitData('fresh output');
    // Force the lastOutputAt to a specific value we can assert against.
    session.lastOutputAt = 5_000;

    // Now reap at t = 5000 + idleTtl - 1 → not yet expired relative to lastOutputAt.
    const reaped = mgr.reapIdle(5_000 + CFG.idleTtlMs - 1);
    expect(reaped).toBe(0);
    expect(mgr.get(id)).toBeDefined();
    expect((session.pty as MockIPty).killed).toBe(false);
  });

  it('reaps a detached session whose max(detachedAt, lastOutputAt) + idleTtl has passed (M3)', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const session = mgr.handleAttach(ws, null, DIMS, 1_000);
    const id = session.meta.id;

    // Detach at t=2000; no output after detach.
    session.clients.clear();
    session.detachedAt = 2_000;
    session.lastOutputAt = 1_500; // before detach → max = 2000

    // Reap at t = 2000 + idleTtl + 1 → expired.
    const reaped = mgr.reapIdle(2_000 + CFG.idleTtlMs + 1);
    expect(reaped).toBe(1);
    expect(mgr.get(id)).toBeUndefined();
    expect((session.pty as MockIPty).killed).toBe(true);
  });

  it('reaps multiple idle sessions and returns the count', () => {
    const mgr = createSessionManager(CFG);

    // Session A — will be reaped.
    nextPty = createMockPty();
    const wsA = createMockWs();
    const sessionA = mgr.handleAttach(wsA, null, DIMS, 1_000);
    sessionA.clients.clear();
    sessionA.detachedAt = 1_000;
    sessionA.lastOutputAt = 1_000;

    // Session B — will be reaped.
    nextPty = createMockPty();
    const wsB = createMockWs();
    const sessionB = mgr.handleAttach(wsB, null, DIMS, 1_000);
    sessionB.clients.clear();
    sessionB.detachedAt = 1_000;
    sessionB.lastOutputAt = 1_000;

    const reaped = mgr.reapIdle(1_000 + CFG.idleTtlMs + 1);
    expect(reaped).toBe(2);
    expect(mgr.get(sessionA.meta.id)).toBeUndefined();
    expect(mgr.get(sessionB.meta.id)).toBeUndefined();
  });

  it('does not reap if detachedAt is null (still attached / never detached)', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const session = mgr.handleAttach(ws, null, DIMS, 1_000);
    // detachedAt is null — session is still live.

    const reaped = mgr.reapIdle(99_999_999);
    expect(reaped).toBe(0);
    expect(mgr.get(session.meta.id)).toBeDefined();
  });
});

// ── list (v0.4 multi-device discovery) ────────────────────────────────────────
describe('list', () => {
  it('returns live sessions with client counts, newest first', () => {
    const mgr = createSessionManager(CFG);

    nextPty = createMockPty();
    const a = mgr.handleAttach(createMockWs(), null, DIMS, 1_000);
    nextPty = createMockPty();
    const b = mgr.handleAttach(createMockWs(), null, DIMS, 2_000);
    // a second device joins session b → clientCount 2
    mgr.handleAttach(createMockWs(), b.meta.id, DIMS, 2_500);

    const list = mgr.list();
    expect(list.map((s) => s.id)).toEqual([b.meta.id, a.meta.id]); // newest first
    expect(list.find((s) => s.id === b.meta.id)?.clientCount).toBe(2);
    expect(list.find((s) => s.id === a.meta.id)?.clientCount).toBe(1);
    expect(list.every((s) => s.exited === false)).toBe(true);
  });

  it('returns an empty array when there are no sessions', () => {
    const mgr = createSessionManager(CFG);
    expect(mgr.list()).toEqual([]);
  });
});

// ── shutdown ──────────────────────────────────────────────────────────────────
describe('shutdown', () => {
  it('kills all sessions and clears the table', () => {
    const mgr = createSessionManager(CFG);

    nextPty = createMockPty();
    const ws1 = createMockWs();
    const s1 = mgr.handleAttach(ws1, null, DIMS, 1_000);

    nextPty = createMockPty();
    const ws2 = createMockWs();
    const s2 = mgr.handleAttach(ws2, null, DIMS, 1_000);

    mgr.shutdown();

    expect((s1.pty as MockIPty).killed).toBe(true);
    expect((s2.pty as MockIPty).killed).toBe(true);

    // Table is cleared.
    expect(mgr.get(s1.meta.id)).toBeUndefined();
    expect(mgr.get(s2.meta.id)).toBeUndefined();
  });
});

// ── maxSessions DoS cap (Sec H1) ──────────────────────────────────────────────
describe('handleAttach — session cap', () => {
  it('throws once the table is at cfg.maxSessions (new-session path)', () => {
    const cappedCfg: Config = { ...CFG, maxSessions: 2 };
    const mgr = createSessionManager(cappedCfg);

    nextPty = createMockPty();
    mgr.handleAttach(createMockWs(), null, DIMS, 1_000);
    nextPty = createMockPty();
    mgr.handleAttach(createMockWs(), null, DIMS, 1_000);

    // Third new session must be refused (reuses the M4 exit(-1) path in server).
    nextPty = createMockPty();
    expect(() => mgr.handleAttach(createMockWs(), null, DIMS, 1_000)).toThrow(/limit/i);
  });

  it('also caps the not-found path (unknown id → would create)', () => {
    const cappedCfg: Config = { ...CFG, maxSessions: 1 };
    const mgr = createSessionManager(cappedCfg);
    mgr.handleAttach(createMockWs(), null, DIMS, 1_000);

    const unknown = '00000000-0000-4000-8000-000000000099';
    nextPty = createMockPty();
    expect(() => mgr.handleAttach(createMockWs(), unknown, DIMS, 1_000)).toThrow(/limit/i);
  });

  it('JOINing an existing session does NOT count against the cap', () => {
    const cappedCfg: Config = { ...CFG, maxSessions: 1 };
    const mgr = createSessionManager(cappedCfg);
    const s = mgr.handleAttach(createMockWs(), null, DIMS, 1_000);

    // A second device joining the same session must be allowed at the cap.
    expect(() => mgr.handleAttach(createMockWs(), s.meta.id, DIMS, 2_000)).not.toThrow();
    expect(s.clients.size).toBe(2);
  });
});

// ── killById (manage page) ────────────────────────────────────────────────────
describe('killById', () => {
  it('closes all clients, kills the PTY, and removes the session', () => {
    const mgr = createSessionManager(CFG);
    const a = createMockWs();
    const b = createMockWs();
    const s = mgr.handleAttach(a, null, DIMS, 1_000);
    mgr.handleAttach(b, s.meta.id, DIMS, 2_000);

    const ok = mgr.killById(s.meta.id);

    expect(ok).toBe(true);
    expect(a.closed).toBe(true);
    expect(b.closed).toBe(true);
    expect((s.pty as MockIPty).killed).toBe(true);
    expect(mgr.get(s.meta.id)).toBeUndefined();
  });

  it('returns false for an unknown id', () => {
    const mgr = createSessionManager(CFG);
    expect(mgr.killById('00000000-0000-4000-8000-0000000000aa')).toBe(false);
  });
});

// ── handleHookEvent (H2/H3 status push) ───────────────────────────────────────
describe('handleHookEvent', () => {
  it('sets claudeStatus and broadcasts a status frame to all clients', () => {
    const mgr = createSessionManager(CFG);
    const a = createMockWs();
    const b = createMockWs();
    const s = mgr.handleAttach(a, null, DIMS, 1_000);
    mgr.handleAttach(b, s.meta.id, DIMS, 2_000);
    a.sent.length = 0;
    b.sent.length = 0;

    mgr.handleHookEvent(s.meta.id, 'waiting', 'Bash', true);

    expect(s.claudeStatus).toBe('waiting');
    for (const ws of [a, b]) {
      const status = parseSent(ws).find((m) => m.type === 'status');
      expect(status).toMatchObject({ type: 'status', status: 'waiting', detail: 'Bash', pending: true });
    }
  });

  it('omits detail/pending when not supplied', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    ws.sent.length = 0;

    mgr.handleHookEvent(s.meta.id, 'idle');

    const status = parseSent(ws).find((m) => m.type === 'status');
    expect(status).toEqual({ type: 'status', status: 'idle' });
  });

  it('is a no-op for an unknown session id', () => {
    const mgr = createSessionManager(CFG);
    expect(() => mgr.handleHookEvent('00000000-0000-4000-8000-0000000000bb', 'working')).not.toThrow();
  });
});

// ── L2: injected onExit removes session when ws is attached at exit time ───────
describe('onExit removes session from table when ws attached at exit time (L2)', () => {
  it('session is removed from the table when PTY exits while ws is attached', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const session = mgr.handleAttach(ws, null, DIMS, 1_000);
    const id = session.meta.id;

    // PTY exits while ws is still attached.
    (session.pty as MockIPty).emitExit(0);

    // The manager's onExit should have removed the session.
    expect(mgr.get(id)).toBeUndefined();
  });

  it('session is NOT removed from table when PTY exits while detached (kept for L1 replay)', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const session = mgr.handleAttach(ws, null, DIMS, 1_000);
    const id = session.meta.id;

    // Detach first.
    session.clients.clear();
    session.detachedAt = 2_000;

    // Then PTY exits.
    (session.pty as MockIPty).emitExit(0);

    // Session must stay in table for L1 replay.
    expect(mgr.get(id)).toBeDefined();
    expect(session.exitedAt).not.toBeNull();
  });
});

// ── handleHookEvent — A4 timeline + B4 gate (T-manager) ───────────────────────
describe('handleHookEvent — timeline append (A4)', () => {
  it('appends a derived timeline event when eventClass is supplied + timeline enabled', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    mgr.handleHookEvent(s.meta.id, 'working', 'Bash', false, undefined, 'PreToolUse', 'Bash');

    expect(s.timeline).toHaveLength(1);
    expect(s.timeline[0]).toMatchObject({ class: 'tool', toolName: 'Bash', label: 'using Bash' });
    expect(typeof s.timeline[0]?.at).toBe('number');
  });

  it('replaces the timeline array immutably (never mutates the previous one)', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    const before = s.timeline;

    mgr.handleHookEvent(s.meta.id, 'working', undefined, false, undefined, 'PreToolUse', 'Bash');

    expect(s.timeline).not.toBe(before);
    expect(before).toHaveLength(0);
  });

  it('does NOT append when timeline is disabled', () => {
    const mgr = createSessionManager({ ...CFG, timelineEnabled: false });
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    mgr.handleHookEvent(s.meta.id, 'working', undefined, false, undefined, 'PreToolUse', 'Bash');

    expect(s.timeline).toHaveLength(0);
  });

  it('does NOT append when eventClass is omitted', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    mgr.handleHookEvent(s.meta.id, 'waiting', 'Bash', true);

    expect(s.timeline).toHaveLength(0);
  });

  it('drops non-whitelisted event classes (makeTimelineEvent → null)', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    mgr.handleHookEvent(s.meta.id, 'working', undefined, false, undefined, 'BogusEvent', 'X');

    expect(s.timeline).toHaveLength(0);
  });

  it('evicts oldest events past cfg.timelineMax', () => {
    const mgr = createSessionManager({ ...CFG, timelineMax: 3 });
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    for (let i = 0; i < 5; i += 1) {
      mgr.handleHookEvent(s.meta.id, 'working', undefined, false, undefined, 'PreToolUse', `Tool${i}`);
    }

    expect(s.timeline).toHaveLength(3);
    expect(s.timeline.map((e) => e.toolName)).toEqual(['Tool2', 'Tool3', 'Tool4']);
  });
});

describe('handleHookEvent — gate broadcast (B4)', () => {
  it('broadcasts the status frame with gate when supplied', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    ws.sent.length = 0;

    mgr.handleHookEvent(s.meta.id, 'waiting', 'ExitPlanMode', true, 'plan', 'PermissionRequest', 'ExitPlanMode');

    const status = parseSent(ws).find((m) => m.type === 'status');
    expect(status).toMatchObject({
      type: 'status',
      status: 'waiting',
      detail: 'ExitPlanMode',
      pending: true,
      gate: 'plan',
    });
  });

  it('omits gate when not supplied', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    ws.sent.length = 0;

    mgr.handleHookEvent(s.meta.id, 'waiting', 'Bash', true);

    const status = parseSent(ws).find((m) => m.type === 'status');
    expect(status).not.toHaveProperty('gate');
  });
});

// ── handleHookEvent — W1 preview broadcast ────────────────────────────────────
describe('handleHookEvent — preview broadcast (W1)', () => {
  it('puts the preview arg on the broadcast status frame (deep equal)', () => {
    const mgr = createSessionManager(CFG);
    const a = createMockWs();
    const b = createMockWs();
    const s = mgr.handleAttach(a, null, DIMS, 1_000);
    mgr.handleAttach(b, s.meta.id, DIMS, 2_000);
    a.sent.length = 0;
    b.sent.length = 0;

    const preview = { kind: 'command', text: 'ls -la' } as const;
    mgr.handleHookEvent(s.meta.id, 'waiting', 'Bash', true, 'tool', undefined, undefined, preview);

    for (const ws of [a, b]) {
      const status = parseSent(ws).find((m) => m.type === 'status');
      expect(status.preview).toEqual(preview);
    }
  });

  it('omits the preview key when no preview is supplied', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    ws.sent.length = 0;

    mgr.handleHookEvent(s.meta.id, 'waiting', 'Bash', true, 'tool');

    const status = parseSent(ws).find((m) => m.type === 'status');
    expect(status).not.toHaveProperty('preview');
  });
});

// ── handleStatusLine (B2 telemetry) ───────────────────────────────────────────
describe('handleStatusLine', () => {
  it('stores telemetry on the session and broadcasts it to all clients', () => {
    const mgr = createSessionManager(CFG);
    const a = createMockWs();
    const b = createMockWs();
    const s = mgr.handleAttach(a, null, DIMS, 1_000);
    mgr.handleAttach(b, s.meta.id, DIMS, 2_000);
    a.sent.length = 0;
    b.sent.length = 0;

    const telemetry = makeTelemetry();
    mgr.handleStatusLine(s.meta.id, telemetry);

    expect(s.telemetry).toBe(telemetry);
    for (const ws of [a, b]) {
      const msg = parseSent(ws).find((m) => m.type === 'telemetry');
      expect(msg).toMatchObject({ type: 'telemetry', telemetry: { costUsd: 1.23, model: 'sonnet' } });
    }
  });

  it('is a no-op for an unknown session id', () => {
    const mgr = createSessionManager(CFG);
    expect(() => mgr.handleStatusLine('00000000-0000-4000-8000-0000000000cc', makeTelemetry())).not.toThrow();
  });
});

// ── handleAttach Case 2 — late-join telemetry/status replay (M3 / AC-B2.3) ─────
describe('handleAttach — late-join replay (M3)', () => {
  it('sends the current telemetry to a device joining a live session', () => {
    const mgr = createSessionManager(CFG);
    const a = createMockWs();
    const s = mgr.handleAttach(a, null, DIMS, 1_000);
    mgr.handleStatusLine(s.meta.id, makeTelemetry());

    const b = createMockWs();
    mgr.handleAttach(b, s.meta.id, DIMS, 2_000);

    const msg = parseSent(b).find((m) => m.type === 'telemetry');
    expect(msg).toMatchObject({ type: 'telemetry', telemetry: { model: 'sonnet' } });
  });

  it('sends the current status to a late-joining device', () => {
    const mgr = createSessionManager(CFG);
    const a = createMockWs();
    const s = mgr.handleAttach(a, null, DIMS, 1_000);
    mgr.handleHookEvent(s.meta.id, 'working');

    const b = createMockWs();
    mgr.handleAttach(b, s.meta.id, DIMS, 2_000);

    const status = parseSent(b).find((m) => m.type === 'status');
    expect(status).toMatchObject({ type: 'status', status: 'working' });
  });

  it('does NOT send a telemetry frame when the session has no telemetry yet', () => {
    const mgr = createSessionManager(CFG);
    const a = createMockWs();
    const s = mgr.handleAttach(a, null, DIMS, 1_000);

    const b = createMockWs();
    mgr.handleAttach(b, s.meta.id, DIMS, 2_000);

    expect(parseSent(b).some((m) => m.type === 'telemetry')).toBe(false);
  });
});

// ── sweepStuck (A5) ───────────────────────────────────────────────────────────
describe('sweepStuck (A5)', () => {
  it('marks a silent live session stuck, broadcasts, and notifies once', () => {
    const { service, notify } = createMockNotify();
    const mgr = createSessionManager(CFG, service);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000); // lastOutputAt = 1000
    ws.sent.length = 0;

    mgr.sweepStuck(1_000 + CFG.stuckTtlMs + 1);

    expect(s.claudeStatus).toBe('stuck');
    expect(s.stuckNotified).toBe(true);
    const status = parseSent(ws).find((m) => m.type === 'status');
    expect(status).toMatchObject({ type: 'status', status: 'stuck' });
    expect(notify).toHaveBeenCalledTimes(1);
    expect(notify).toHaveBeenCalledWith(s, 'stuck');
  });

  it('covers ATTACHED sessions, not only detached ones (AC-A5.3)', () => {
    const { service, notify } = createMockNotify();
    const mgr = createSessionManager(CFG, service);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    // still attached: clients.size === 1, detachedAt === null

    mgr.sweepStuck(1_000 + CFG.stuckTtlMs + 1);

    expect(s.detachedAt).toBeNull();
    expect(s.claudeStatus).toBe('stuck');
    expect(notify).toHaveBeenCalledTimes(1);
  });

  it('alerts at most once per silent round (AC-A5.1)', () => {
    const { service, notify } = createMockNotify();
    const mgr = createSessionManager(CFG, service);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    mgr.sweepStuck(1_000 + CFG.stuckTtlMs + 1);
    mgr.sweepStuck(1_000 + CFG.stuckTtlMs + 9_999);

    expect(notify).toHaveBeenCalledTimes(1);
    expect(s.claudeStatus).toBe('stuck');
  });

  it('re-arms after output recovery so a later silence alerts again (AC-A5.2)', () => {
    const { service, notify } = createMockNotify();
    const mgr = createSessionManager(CFG, service);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    mgr.sweepStuck(1_000 + CFG.stuckTtlMs + 1);
    expect(notify).toHaveBeenCalledTimes(1);

    // Output recovery (session.ts onData) re-arms the flag + status.
    (s.pty as MockIPty).emitData('back to work');
    expect(s.stuckNotified).toBe(false);
    expect(s.claudeStatus).toBe('working');
    s.lastOutputAt = 100_000; // pin to a known cursor

    mgr.sweepStuck(100_000 + CFG.stuckTtlMs + 1);
    expect(notify).toHaveBeenCalledTimes(2);
    expect(s.claudeStatus).toBe('stuck');
  });

  it('skips idle sessions', () => {
    const { service, notify } = createMockNotify();
    const mgr = createSessionManager(CFG, service);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    s.claudeStatus = 'idle';

    mgr.sweepStuck(1_000 + CFG.stuckTtlMs + 1);

    expect(s.claudeStatus).toBe('idle');
    expect(notify).not.toHaveBeenCalled();
  });

  it('skips already-exited sessions (kept in table after detach-then-exit)', () => {
    const { service, notify } = createMockNotify();
    const mgr = createSessionManager(CFG, service);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    s.clients.clear();
    s.detachedAt = 2_000;
    (s.pty as MockIPty).emitExit(0); // detached-then-exit → stays in table (L1)

    mgr.sweepStuck(1_000 + CFG.stuckTtlMs + 1);

    expect(s.claudeStatus).not.toBe('stuck');
    expect(notify).not.toHaveBeenCalled();
  });

  it('does not mark a session whose output is within the TTL window', () => {
    const { service, notify } = createMockNotify();
    const mgr = createSessionManager(CFG, service);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    mgr.sweepStuck(1_000 + CFG.stuckTtlMs - 1);

    expect(s.claudeStatus).not.toBe('stuck');
    expect(notify).not.toHaveBeenCalled();
  });

  it('is disabled when stuckAlert is false', () => {
    const { service, notify } = createMockNotify();
    const mgr = createSessionManager({ ...CFG, stuckAlert: false }, service);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    mgr.sweepStuck(1_000 + CFG.stuckTtlMs + 1);

    expect(s.claudeStatus).not.toBe('stuck');
    expect(notify).not.toHaveBeenCalled();
  });

  it('is disabled when stuckTtlMs is 0', () => {
    const { service, notify } = createMockNotify();
    const mgr = createSessionManager({ ...CFG, stuckTtlMs: 0 }, service);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    mgr.sweepStuck(99_999_999);

    expect(s.claudeStatus).not.toBe('stuck');
    expect(notify).not.toHaveBeenCalled();
  });

  it('swallows a notifyService rejection (logs via console.error, never throws)', async () => {
    const errSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
    const notify = vi.fn(async () => {
      throw new Error('push transport down');
    });
    const service: NotifyService = { isEnabled: () => true, notify };
    const mgr = createSessionManager(CFG, service);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    expect(() => mgr.sweepStuck(1_000 + CFG.stuckTtlMs + 1)).not.toThrow();
    await Promise.resolve();
    await Promise.resolve();

    expect(s.claudeStatus).toBe('stuck');
    expect(errSpy).toHaveBeenCalled();
    errSpy.mockRestore();
  });

  it('works without an injected notifyService (broadcasts, no throw)', () => {
    const mgr = createSessionManager(CFG); // no notifyService
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    ws.sent.length = 0;

    expect(() => mgr.sweepStuck(1_000 + CFG.stuckTtlMs + 1)).not.toThrow();
    expect(s.claudeStatus).toBe('stuck');
    expect(parseSent(ws).some((m) => m.type === 'status' && m.status === 'stuck')).toBe(true);
  });
});

// ── list() carries telemetry (B2 thumbnail wall) ──────────────────────────────
describe('list — telemetry field', () => {
  it('includes the latest telemetry for each session', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    const telemetry = makeTelemetry();
    mgr.handleStatusLine(s.meta.id, telemetry);

    const entry = mgr.list().find((e) => e.id === s.meta.id);
    expect(entry?.telemetry).toBe(telemetry);
  });

  it('reports null telemetry before the first statusLine report', () => {
    const mgr = createSessionManager(CFG);
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);

    const entry = mgr.list().find((e) => e.id === s.meta.id);
    expect(entry?.telemetry).toBeNull();
  });
});

// ── list() carries lastOutputAt (T-iOS-37 unread watermark) ───────────────────
// The runtime record (Session.lastOutputAt, refreshed on every pty.onData — M3)
// is serialized into LiveSessionInfo so clients can compute an unread dot
// (lastOutputAt > local last-seen). Additive OPTIONAL field: existing consumers
// (preview grid, projects panel) are unaffected.
describe('list — lastOutputAt field (T-iOS-37)', () => {
  it('includes lastOutputAt matching the session runtime record after output flows', () => {
    const mgr = createSessionManager(CFG);
    nextPty = createMockPty();
    const s = mgr.handleAttach(createMockWs(), null, DIMS, 1_000);

    // Output flows → session.ts pty.onData refreshes the runtime record with
    // Date.now(); list() must serialize exactly that value.
    const before = Date.now();
    (s.pty as MockIPty).emitData('hello from claude');

    const entry = mgr.list().find((e) => e.id === s.meta.id);
    expect(s.lastOutputAt).toBeGreaterThanOrEqual(before);
    expect(entry?.lastOutputAt).toBe(s.lastOutputAt);
  });

  it('serializes a pinned runtime value verbatim (epoch ms, no transformation)', () => {
    const mgr = createSessionManager(CFG);
    nextPty = createMockPty();
    const s = mgr.handleAttach(createMockWs(), null, DIMS, 1_000);

    // Pin the runtime record to a known cursor (same style as the M3 reap tests).
    s.lastOutputAt = 123_456;

    const entry = mgr.list().find((e) => e.id === s.meta.id);
    expect(entry?.lastOutputAt).toBe(123_456);
  });

  it('equals spawn time for a fresh session before any output (createSession inits lastOutputAt = now)', () => {
    const mgr = createSessionManager(CFG);
    nextPty = createMockPty();
    const s = mgr.handleAttach(createMockWs(), null, DIMS, 1_000);

    // createSession initializes lastOutputAt: now (src/session/session.ts) —
    // a fresh session's watermark IS its spawn time, never absent/zero.
    const entry = mgr.list().find((e) => e.id === s.meta.id);
    expect(entry?.lastOutputAt).toBe(1_000);
  });

  it('keeps the existing LiveSessionInfo shape intact (additive optional field)', () => {
    const mgr = createSessionManager(CFG);
    nextPty = createMockPty();
    const s = mgr.handleAttach(createMockWs(), null, DIMS, 1_000);

    const entry = mgr.list().find((e) => e.id === s.meta.id);
    expect(entry).toMatchObject({
      id: s.meta.id,
      createdAt: 1_000,
      clientCount: 1,
      status: 'unknown',
      exited: false,
      cols: 80,
      rows: 24,
      telemetry: null,
    });
  });
});

// ── W2: inject-queue methods (enqueueFollowup / drainOne / clearQueue) ────────
describe('W2 inject queue — enqueueFollowup', () => {
  it('appends and returns {ok,length}, broadcasting {type:queue,length} to clients', () => {
    const mgr = createSessionManager(CFG);
    nextPty = createMockPty();
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    ws.sent.length = 0;

    const r1 = mgr.enqueueFollowup(s.meta.id, 'echo one\r');
    expect(r1).toEqual({ ok: true, length: 1 });
    expect(s.queue).toEqual(['echo one\r']);
    expect(parseSent(ws).some((m) => m.type === 'queue' && m.length === 1)).toBe(true);

    const r2 = mgr.enqueueFollowup(s.meta.id, 'echo two\r');
    expect(r2).toEqual({ ok: true, length: 2 });
    expect(s.queue).toEqual(['echo one\r', 'echo two\r']);
  });

  it('caps at queueMaxItems → {ok:false,reason:full}, no broadcast, queue unchanged', () => {
    const mgr = createSessionManager({ ...CFG, queueMaxItems: 2 });
    nextPty = createMockPty();
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    mgr.enqueueFollowup(s.meta.id, 'a');
    mgr.enqueueFollowup(s.meta.id, 'b');
    ws.sent.length = 0;

    const r = mgr.enqueueFollowup(s.meta.id, 'c');
    expect(r).toEqual({ ok: false, reason: 'full' });
    expect(s.queue).toEqual(['a', 'b']); // immutable: unchanged
    expect(parseSent(ws).some((m) => m.type === 'queue')).toBe(false); // no broadcast
  });

  it('unknown id → {ok:false,reason:unknown}', () => {
    const mgr = createSessionManager(CFG);
    expect(mgr.enqueueFollowup('11111111-1111-4111-8111-111111111111', 'x')).toEqual({
      ok: false,
      reason: 'unknown',
    });
  });

  it('exited session → {ok:false,reason:exited}', () => {
    const mgr = createSessionManager(CFG);
    nextPty = createMockPty();
    const s = mgr.handleAttach(createMockWs(), null, DIMS, 1_000);
    s.exitedAt = 2_000;
    expect(mgr.enqueueFollowup(s.meta.id, 'x')).toEqual({ ok: false, reason: 'exited' });
  });
});

describe('W2 inject queue — drainOne', () => {
  it('pops the head, writes it to the PTY, shrinks the queue, and broadcasts depth', () => {
    const mgr = createSessionManager(CFG);
    nextPty = createMockPty();
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    mgr.enqueueFollowup(s.meta.id, 'HEAD\r');
    mgr.enqueueFollowup(s.meta.id, 'TAIL\r');
    ws.sent.length = 0;
    const pty = s.pty as MockIPty;
    pty.writes.length = 0;

    const drained = mgr.drainOne(s.meta.id);
    expect(drained).toBe('HEAD\r');
    expect(pty.writes).toEqual(['HEAD\r']); // byte-identical inject
    expect(s.queue).toEqual(['TAIL\r']); // length now 1
    expect(parseSent(ws).some((m) => m.type === 'queue' && m.length === 1)).toBe(true);
  });

  it('empty queue → null, no PTY write', () => {
    const mgr = createSessionManager(CFG);
    nextPty = createMockPty();
    const s = mgr.handleAttach(createMockWs(), null, DIMS, 1_000);
    const pty = s.pty as MockIPty;
    pty.writes.length = 0;

    expect(mgr.drainOne(s.meta.id)).toBeNull();
    expect(pty.writes).toEqual([]);
  });

  it('exited session with items queued → null (double-guards L4), no write', () => {
    const mgr = createSessionManager(CFG);
    nextPty = createMockPty();
    const s = mgr.handleAttach(createMockWs(), null, DIMS, 1_000);
    mgr.enqueueFollowup(s.meta.id, 'x');
    s.exitedAt = 2_000;
    const pty = s.pty as MockIPty;
    pty.writes.length = 0;

    expect(mgr.drainOne(s.meta.id)).toBeNull();
    expect(pty.writes).toEqual([]);
  });

  it('unknown id → null', () => {
    const mgr = createSessionManager(CFG);
    expect(mgr.drainOne('11111111-1111-4111-8111-111111111111')).toBeNull();
  });
});

describe('W2 inject queue — clearQueue', () => {
  it('empties the queue, broadcasts length 0, returns true', () => {
    const mgr = createSessionManager(CFG);
    nextPty = createMockPty();
    const ws = createMockWs();
    const s = mgr.handleAttach(ws, null, DIMS, 1_000);
    mgr.enqueueFollowup(s.meta.id, 'a');
    mgr.enqueueFollowup(s.meta.id, 'b');
    ws.sent.length = 0;

    expect(mgr.clearQueue(s.meta.id)).toBe(true);
    expect(s.queue).toEqual([]);
    expect(parseSent(ws).some((m) => m.type === 'queue' && m.length === 0)).toBe(true);
  });

  it('unknown id → false', () => {
    const mgr = createSessionManager(CFG);
    expect(mgr.clearQueue('11111111-1111-4111-8111-111111111111')).toBe(false);
  });
});

describe('W2 inject queue — list() surfaces queueLength', () => {
  it('reports the pending depth per session', () => {
    const mgr = createSessionManager(CFG);
    nextPty = createMockPty();
    const s = mgr.handleAttach(createMockWs(), null, DIMS, 1_000);
    mgr.enqueueFollowup(s.meta.id, 'a');
    mgr.enqueueFollowup(s.meta.id, 'b');

    const entry = mgr.list().find((e) => e.id === s.meta.id);
    expect(entry?.queueLength).toBe(2);
  });
});