auth: distress-password lockdown + explicit token-revoke endpoint

Add a duress password (DISTRESS_PASSWORD env): entering it at login trips an
in-memory full lockdown — all new logins (password + passkey) and every existing
session are refused until the server is restarted, and the login itself returns a
normal "invalid credentials" so it gives nothing away. Also add
POST /api/auth/blacklist-token as a clearly-named alias for revoking the current
JWT (same effect as signout).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/servers/api/auth/auth.ts

@@ -32,6 +32,8 @@ authRouter.use('/', async (ctx) => ctx.json({ officerAuthServer: 'ok' }));
 authRouter.get('/me', userMiddleware, usersMe);
 authRouter.post('/signin', signinRateLimiter, signinHandler);
 authRouter.post('/signout', userMiddleware, signoutHandler);
+// Explicit "revoke the current token" alias (same effect as signout: blacklists this JWT).
+authRouter.post('/blacklist-token', userMiddleware, signoutHandler);
 authRouter.post('/signup', signupRateLimiter, signupHandler);
 authRouter.post('/bootstrap', signupRateLimiter, bootstrapHandler);
 authRouter.post('/verify', verifyHandler);

src/servers/api/auth/distress.ts

@@ -0,0 +1,10 @@
+// Duress lockdown. The distress password (entered at login) trips this in-memory flag; while it is
+// set, ALL new logins and ALL existing sessions are refused. It is intentionally in-memory only, so
+// the only way to clear it is a manual server restart.
+let locked = false;
+
+export const isLockdown = (): boolean => locked;
+
+export const triggerLockdown = (): void => {
+  locked = true;
+};

src/servers/api/auth/passkey-router.ts

@@ -4,6 +4,7 @@ import { createRouter } from '../../create-router';
 import { userMiddleware, passkeyRateLimiter } from '../../_middlewares';
 import { sign } from '../../jwt';
 import * as errors from '../../custom-errors';
+import { isLockdown } from './distress';
 import {
   getUserByEmail,
   getPasskeysByUserIdAndOrigin,
@@ -128,6 +129,7 @@ passkeyRouter.get('/signin/:email', passkeyRateLimiter, passkeyRouterGet);
 
 // Verify passkey authentication and issue token
 const passkeyRouterPostVerify: Handler = async (ctx) => {
+  if (isLockdown()) throw errors.UNAUTHORIZED(); // duress lockdown blocks passkey logins too
   const { email } = ctx.req.param();
   const origin = ctx.get('origin') as string;
   const rpId = getRpId(origin);

src/servers/api/auth/signin.ts

@@ -6,11 +6,22 @@ import { sign } from '@@/jwt';
 import { getClaudeDir } from '@@/data-path';
 import argon2 from 'argon2';
 import * as errors from '@@/custom-errors';
+import { isLockdown, triggerLockdown } from './distress';
 
 const TEST_USERS: number[] = [];
+const { DISTRESS_PASSWORD } = process.env;
 
 export const signinHandler: Handler = async function (ctx) {
   const { email, password } = ctx.get('body');
+
+  // Duress: if lockdown is active, refuse everyone (looks like a normal failed login). If the distress
+  // password was entered, trip the lockdown now and then fail the same way, giving nothing away.
+  if (isLockdown()) throw errors.UNAUTHORIZED();
+  if (DISTRESS_PASSWORD && typeof password === 'string' && password === DISTRESS_PASSWORD) {
+    triggerLockdown();
+    throw errors.UNAUTHORIZED();
+  }
+
   const origin = ctx.get('origin');
   const dbUser = await getUserByEmail(email);
   if (!dbUser) throw errors.UNAUTHORIZED();