feat(telegram): self-contained pairing for chat ownership verification

BotFather issues bot tokens with no user binding, so anyone who guesses the
bot's username can DM it and get registered as a channel. Pairing closes that
gap: setup issues a one-time 4-digit code, the operator echoes it back from
the chat they want to register, and the inbound interceptor binds
admin_user_id before the message reaches the router.

- src/channels/telegram-pairing.ts: JSON-backed store with createPairing,
  tryConsume, getStatus, waitForPairing (fs.watch + poll fallback)
- src/channels/telegram.ts: wraps bridge.setup with an onInbound interceptor
  that consumes pairing codes and upserts messaging_groups
- setup/pair-telegram.ts: CLI step issues a code and waits up to 5 min for
  the operator to echo it back, emitting PLATFORM_ID/IS_GROUP/ADMIN_USER_ID
- Skill docs: /setup reorders mounts -> service -> wire (pairing needs a
  live polling adapter); /manage-channels and /add-telegram-v2 use pairing
  instead of asking the user to discover chat IDs

All other channels still bind admin via install-time identity (OAuth/QR/token);
pairing is Telegram-only. The bridge, router, and other adapters are untouched.

src/channels/telegram-pairing.test.ts

@@ -0,0 +1,166 @@
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+import fs from 'fs';
+import path from 'path';
+import os from 'os';
+
+vi.mock('../log.js', () => ({ log: { info: vi.fn(), warn: vi.fn(), error: vi.fn(), debug: vi.fn() } }));
+
+import {
+  createPairing,
+  tryConsume,
+  getStatus,
+  waitForPairing,
+  extractCode,
+  extractAddressedText,
+  _setStorePathForTest,
+  _resetForTest,
+} from './telegram-pairing.js';
+
+let tmpDir: string;
+
+beforeEach(() => {
+  tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'tg-pair-'));
+  _setStorePathForTest(path.join(tmpDir, 'pairings.json'));
+});
+
+afterEach(() => {
+  _resetForTest();
+  _setStorePathForTest(null);
+  fs.rmSync(tmpDir, { recursive: true, force: true });
+});
+
+describe('extractAddressedText', () => {
+  it('strips @botname prefix', () => {
+    expect(extractAddressedText('@nanobot 1234', 'nanobot')).toBe('1234');
+  });
+  it('is case-insensitive', () => {
+    expect(extractAddressedText('@NanoBot hello', 'nanobot')).toBe('hello');
+  });
+  it('returns null when not addressed', () => {
+    expect(extractAddressedText('hello 1234', 'nanobot')).toBeNull();
+  });
+  it('returns null when address is mid-text', () => {
+    expect(extractAddressedText('hi @nanobot 1234', 'nanobot')).toBeNull();
+  });
+});
+
+describe('extractCode', () => {
+  it('finds 4-digit code after @botname', () => {
+    expect(extractCode('@nanobot 0042', 'nanobot')).toBe('0042');
+  });
+  it('rejects non-4-digit numbers', () => {
+    expect(extractCode('@nanobot 12345', 'nanobot')).toBeNull();
+    expect(extractCode('@nanobot 12', 'nanobot')).toBeNull();
+  });
+  it('returns null without addressing', () => {
+    expect(extractCode('1234', 'nanobot')).toBeNull();
+  });
+});
+
+describe('createPairing', () => {
+  it('generates a 4-digit code with TTL', async () => {
+    const r = await createPairing('main', { ttlMs: 60_000 });
+    expect(r.code).toMatch(/^\d{4}$/);
+    expect(r.status).toBe('pending');
+    expect(Date.parse(r.expiresAt)).toBeGreaterThan(Date.now());
+  });
+
+  it('does not collide with active codes', async () => {
+    const codes = new Set<string>();
+    for (let i = 0; i < 20; i++) {
+      const r = await createPairing('main');
+      expect(codes.has(r.code)).toBe(false);
+      codes.add(r.code);
+    }
+  });
+});
+
+describe('tryConsume', () => {
+  it('matches and marks consumed', async () => {
+    const r = await createPairing('main');
+    const consumed = await tryConsume({
+      text: `@nanobot ${r.code}`,
+      botUsername: 'nanobot',
+      platformId: 'telegram:123',
+      isGroup: false,
+      adminUserId: 'u1',
+    });
+    expect(consumed).not.toBeNull();
+    expect(consumed!.status).toBe('consumed');
+    expect(consumed!.consumed?.platformId).toBe('telegram:123');
+    expect(consumed!.consumed?.adminUserId).toBe('u1');
+    expect(getStatus(r.code)).toBe('consumed');
+  });
+
+  it('returns null on no match (silent drop)', async () => {
+    await createPairing('main');
+    const out = await tryConsume({
+      text: '@nanobot 9999',
+      botUsername: 'nanobot',
+      platformId: 'x',
+      isGroup: false,
+    });
+    expect(out).toBeNull();
+  });
+
+  it('returns null without @botname addressing', async () => {
+    const r = await createPairing('main');
+    const out = await tryConsume({
+      text: r.code,
+      botUsername: 'nanobot',
+      platformId: 'x',
+      isGroup: false,
+    });
+    expect(out).toBeNull();
+  });
+
+  it('cannot be consumed twice', async () => {
+    const r = await createPairing('main');
+    await tryConsume({ text: `@b ${r.code}`, botUsername: 'b', platformId: 'p', isGroup: false });
+    const second = await tryConsume({ text: `@b ${r.code}`, botUsername: 'b', platformId: 'p', isGroup: false });
+    expect(second).toBeNull();
+  });
+
+  it('cannot consume an expired pairing', async () => {
+    const r = await createPairing('main', { ttlMs: 1 });
+    await new Promise((res) => setTimeout(res, 10));
+    const out = await tryConsume({ text: `@b ${r.code}`, botUsername: 'b', platformId: 'p', isGroup: false });
+    expect(out).toBeNull();
+    expect(getStatus(r.code)).toBe('expired');
+  });
+});
+
+describe('getStatus', () => {
+  it('returns unknown for missing codes', () => {
+    expect(getStatus('0000')).toBe('unknown');
+  });
+});
+
+describe('waitForPairing', () => {
+  it('resolves when consumed', async () => {
+    const r = await createPairing('main', { ttlMs: 5000 });
+    const p = waitForPairing(r.code, { pollMs: 50 });
+    setTimeout(() => {
+      tryConsume({ text: `@b ${r.code}`, botUsername: 'b', platformId: 'tg:1', isGroup: true, name: 'Group' });
+    }, 100);
+    const consumed = await p;
+    expect(consumed.status).toBe('consumed');
+    expect(consumed.consumed?.name).toBe('Group');
+  });
+
+  it('rejects on expiry', async () => {
+    const r = await createPairing('main', { ttlMs: 100 });
+    await expect(waitForPairing(r.code, { pollMs: 30 })).rejects.toThrow(/expired/);
+  });
+});
+
+describe('intent passthrough', () => {
+  it('preserves wire-to and new-agent intents', async () => {
+    const a = await createPairing({ kind: 'wire-to', folder: 'work' });
+    const b = await createPairing({ kind: 'new-agent', folder: 'side' });
+    const ca = await tryConsume({ text: `@b ${a.code}`, botUsername: 'b', platformId: 'p1', isGroup: true });
+    const cb = await tryConsume({ text: `@b ${b.code}`, botUsername: 'b', platformId: 'p2', isGroup: true });
+    expect(ca!.intent).toEqual({ kind: 'wire-to', folder: 'work' });
+    expect(cb!.intent).toEqual({ kind: 'new-agent', folder: 'side' });
+  });
+});