fix(browse): CLI always sends explicit pair scopes via shared DEFAULT_PAIR_SCOPES

The effective pairing default lived in two places: the CLI omitted scopes
unless --restrict was passed, and the server filled in its own literal.
handlePairAgent now always sends an explicit scopes list and both sides
reference one exported constant, DEFAULT_PAIR_SCOPES, so the default cannot
silently drift again (pinned by a server-auth source tripwire).

Three input traps closed in the same surface:
- Bare --restrict (or --restrict swallowing the next flag) parsed as "no
  restriction" and silently granted FULL access, the opposite of the user's
  intent. validatePairAgentFlags rejects it pre-server, before any consent
  gate, so an arg error never boots a daemon.
- A scopes list could smuggle the control scope past the explicit flag:
  --restrict "read,control" minted a control-scoped session with no
  --control. /pair now 400s on control in a scopes list without the control
  flag, and the CLI points the user at --control.
- Option typos validated only at exchange time: createSetupKey stored any
  scope string and any rateLimit, so /pair returned 200 with a poisoned
  setup key whose failure surfaced to the REMOTE agent at /connect as a
  misleading "Invalid request body". Shared validation now runs in both
  creators and throws typed InvalidScopeError; /pair and /token 400 with the
  message, naming the bad scope or negative rateLimit. Also
  `opts.rateLimit || 10` became `?? 10` so the documented "0 = unlimited"
  survives the /pair path.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

browse/test/pair-agent-e2e.test.ts

@@ -194,6 +194,76 @@ describe('pair-agent flow end-to-end (HTTP only, no ngrok)', () => {
     expect(Array.isArray(scopes)).toBe(true);
   });
 
+  // ─── Pair scope contract: defaults, explicit lists, typo naming ───────
+
+  test('default /connect scopes are exactly read,write,admin,meta', async () => {
+    const pairResp = await fetch(`${daemon.baseUrl}/pair`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${daemon.token}` },
+      body: JSON.stringify({ clientId: 'default-scopes' }),
+    });
+    const { setup_key, scopes: pairScopes } = await pairResp.json() as any;
+    expect(pairScopes).toEqual(['read', 'write', 'admin', 'meta']);
+    const connectResp = await fetch(`${daemon.baseUrl}/connect`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ setup_key }),
+    });
+    const { scopes } = await connectResp.json() as any;
+    expect(scopes).toEqual(['read', 'write', 'admin', 'meta']);
+  });
+
+  test('explicit scopes are honored end-to-end (the --restrict wire contract)', async () => {
+    const pairResp = await fetch(`${daemon.baseUrl}/pair`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${daemon.token}` },
+      body: JSON.stringify({ clientId: 'restricted-scopes', scopes: ['read'] }),
+    });
+    const { setup_key } = await pairResp.json() as any;
+    const connectResp = await fetch(`${daemon.baseUrl}/connect`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ setup_key }),
+    });
+    const { scopes } = await connectResp.json() as any;
+    expect(scopes).toEqual(['read']);
+  });
+
+  test('POST /pair with a scope typo fails fast, naming the scope', async () => {
+    // Regression: pre-fix this returned 200 with a poisoned setup key whose
+    // failure surfaced at /connect as a misleading "Invalid request body".
+    const resp = await fetch(`${daemon.baseUrl}/pair`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${daemon.token}` },
+      body: JSON.stringify({ clientId: 'typo-agent', scopes: ['raed'] }),
+    });
+    expect(resp.status).toBe(400);
+    const body = await resp.json() as any;
+    expect(body.error).toContain('Invalid scope: raed');
+  });
+
+  test('POST /token with a scope typo names the scope too', async () => {
+    const resp = await fetch(`${daemon.baseUrl}/token`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${daemon.token}` },
+      body: JSON.stringify({ clientId: 'typo-token', scopes: ['wirte'] }),
+    });
+    expect(resp.status).toBe(400);
+    const body = await resp.json() as any;
+    expect(body.error).toContain('Invalid scope: wirte');
+  });
+
+  test('control cannot ride in through a /pair scopes list without the control flag', async () => {
+    const resp = await fetch(`${daemon.baseUrl}/pair`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${daemon.token}` },
+      body: JSON.stringify({ clientId: 'sneaky', scopes: ['read', 'control'] }),
+    });
+    expect(resp.status).toBe(400);
+    const body = await resp.json() as any;
+    expect(body.error).toContain('control');
+  });
+
   // ─── Revocation e2e: revoke-all + the /agents verification surface ────
 
   test('DELETE /token revokes session AND setup keys; agent leaves /agents; token 401s; re-connect fails', async () => {

browse/test/server-auth.test.ts

@@ -409,3 +409,32 @@ describe('Server auth security', () => {
     expect(routeSrc).toContain('SameSite=Strict');
   });
 });
+
+describe('Pair scope defaults and revocation surface', () => {
+  // Regression: the CLI only sent scopes when --restrict was passed, so the
+  // effective pairing default lived in two places (CLI omission + server
+  // fallback) and could silently drift. Both sides must reference the shared
+  // DEFAULT_PAIR_SCOPES constant, and the CLI must send scopes
+  // unconditionally (the old conditional-spread shape is banned).
+  test('/pair default and CLI pairing body share DEFAULT_PAIR_SCOPES', () => {
+    const pairBlock = sliceBetween(SERVER_SRC, "url.pathname === '/pair'", "url.pathname === '/tunnel/start'");
+    expect(pairBlock).toContain('DEFAULT_PAIR_SCOPES');
+    const cliBlock = sliceBetween(CLI_SRC, 'async function handlePairAgent', 'Determine the URL to use');
+    expect(cliBlock).toContain('DEFAULT_PAIR_SCOPES');
+    expect(cliBlock).not.toContain('...(restrict ? { scopes');
+  });
+
+  // control is the only scope behind an explicit flag; a scopes list must
+  // not be able to smuggle it into a pairing grant.
+  test('/pair rejects control inside a scopes list without the control flag', () => {
+    const pairBlock = sliceBetween(SERVER_SRC, "url.pathname === '/pair'", "url.pathname === '/tunnel/start'");
+    expect(pairBlock).toContain("pairBody.scopes.includes('control')");
+  });
+
+  // CLI-encoded clientIds (spaces, UTF-8) must round-trip through the revoke
+  // route; slicing the raw pathname 404s on every encoded name.
+  test('DELETE /token decodes the clientId path segment', () => {
+    const revokeBlock = sliceBetween(SERVER_SRC, "url.pathname.startsWith('/token/')", "url.pathname === '/agents'");
+    expect(revokeBlock).toContain('decodeURIComponent');
+  });
+});

browse/test/token-registry.test.ts

@@ -6,6 +6,7 @@ import {
   revokeToken, rotateRoot, listTokens, recordCommand,
   serializeRegistry, restoreRegistry, checkConnectRateLimit,
   SCOPE_READ, SCOPE_WRITE, SCOPE_ADMIN, SCOPE_CONTROL, SCOPE_META,
+  DEFAULT_PAIR_SCOPES, InvalidScopeError,
   __resetRegistry,
 } from '../src/token-registry';
 
@@ -347,6 +348,35 @@ describe('token-registry', () => {
     });
   });
 
+  describe('pair defaults and option validation', () => {
+    it('DEFAULT_PAIR_SCOPES is exactly read,write,admin,meta (b73f3644: the ceremony is the trust boundary)', () => {
+      expect([...DEFAULT_PAIR_SCOPES]).toEqual(['read', 'write', 'admin', 'meta']);
+    });
+
+    // Regression: only createToken validated options, so a scope typo minted
+    // a poisoned setup key at /pair and surfaced to the REMOTE agent at
+    // /connect as a misleading "Invalid request body".
+    it('createSetupKey rejects an unknown scope with InvalidScopeError naming it', () => {
+      expect(() => createSetupKey({ scopes: ['raed' as never] }))
+        .toThrow(InvalidScopeError);
+      expect(() => createSetupKey({ scopes: ['raed' as never] }))
+        .toThrow('Invalid scope: raed');
+    });
+
+    it('createSetupKey rejects a negative rateLimit', () => {
+      expect(() => createSetupKey({ rateLimit: -5 })).toThrow(InvalidScopeError);
+    });
+
+    // Regression: `opts.rateLimit || 10` coerced the documented "0 = unlimited"
+    // into 10 on the /pair path while /token honored it.
+    it('createSetupKey preserves rateLimit 0 (unlimited)', () => {
+      const setup = createSetupKey({ rateLimit: 0 });
+      expect(setup.rateLimit).toBe(0);
+      const session = exchangeSetupKey(setup.token)!;
+      expect(session.rateLimit).toBe(0);
+    });
+  });
+
   describe('rotateRoot', () => {
     it('generates new root and invalidates all tokens', () => {
       const oldRoot = getRootToken();

browse/test/tunnel-revoke-cli.test.ts

@@ -97,6 +97,50 @@ describe('tunnel subcommand parsing', () => {
   }, 60_000);
 });
 
+// pair-agent scope-flag misuse shares this file's subprocess harness: like
+// tunnel, the validation must run pre-server, so "no daemon spawned" is the
+// load-bearing assertion.
+describe('pair-agent scope-flag validation (pre-server)', () => {
+  test('bare --restrict → exit 1 usage error, NO daemon spawned (was: silent FULL grant)', async () => {
+    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'browse-restrict-bare-'));
+    const stateFile = path.join(tmpDir, 'browse.json');
+    try {
+      const result = await runCli(['pair-agent', '--restrict'], baseEnv(stateFile));
+      expect(result.code).toBe(1);
+      expect(result.stderr).toContain('--restrict needs a scope list');
+      expect(fs.existsSync(stateFile)).toBe(false);
+    } finally {
+      fs.rmSync(tmpDir, { recursive: true, force: true });
+    }
+  }, 30_000);
+
+  test('--restrict swallowing the next flag → exit 1, NO daemon spawned', async () => {
+    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'browse-restrict-flag-'));
+    const stateFile = path.join(tmpDir, 'browse.json');
+    try {
+      const result = await runCli(['pair-agent', '--restrict', '--client', 'bob'], baseEnv(stateFile));
+      expect(result.code).toBe(1);
+      expect(result.stderr).toContain('--restrict needs a scope list');
+      expect(fs.existsSync(stateFile)).toBe(false);
+    } finally {
+      fs.rmSync(tmpDir, { recursive: true, force: true });
+    }
+  }, 30_000);
+
+  test('--restrict "read,control" → exit 1 pointing at --control, NO daemon spawned', async () => {
+    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'browse-restrict-ctl-'));
+    const stateFile = path.join(tmpDir, 'browse.json');
+    try {
+      const result = await runCli(['pair-agent', '--restrict', 'read,control'], baseEnv(stateFile));
+      expect(result.code).toBe(1);
+      expect(result.stderr).toContain('Re-run with --control');
+      expect(fs.existsSync(stateFile)).toBe(false);
+    } finally {
+      fs.rmSync(tmpDir, { recursive: true, force: true });
+    }
+  }, 30_000);
+});
+
 describe('tunnel against no daemon (#2254 — never boot one)', () => {
   test('revoke → exit 0, "No daemon running", nothing spawned', async () => {
     const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'browse-tunnel-dead-'));