fix(voice): validate Codex OAuth and report unknown usage

server/providers/openai/codex-auth.js

@@ -1,5 +1,10 @@
 import { spawn } from 'node:child_process';
-import { accessSync, constants as fsConstants, readFileSync } from 'node:fs';
+import {
+  accessSync,
+  constants as fsConstants,
+  readFileSync,
+  statSync,
+} from 'node:fs';
 import os from 'node:os';
 import path from 'node:path';
 
@@ -16,22 +21,88 @@ export function codexAuthPath({
   );
 }
 
+/** An optional operator lock that refuses the metered API-key voice lane. */
+export function preferCodexOAuth(environment = process.env) {
+  if (!Object.hasOwn(environment, 'GEV_PREFER_CODEX_OAUTH')) return false;
+  const value = String(environment.GEV_PREFER_CODEX_OAUTH || '')
+    .trim()
+    .toLowerCase();
+  if (['1', 'true', 'yes', 'on'].includes(value)) return true;
+  if (['0', 'false', 'no', 'off'].includes(value)) return false;
+  throw new Error(
+    'GEV_PREFER_CODEX_OAUTH must be true or false. Refusing to choose a voice auth mode.',
+  );
+}
+
 export function readCodexOAuthAccessToken({
   authPath = codexAuthPath(),
   readFile = readFileSync,
+  statFile = statSync,
+  nowMs = Date.now(),
 } = {}) {
+  const unavailable =
+    'ChatGPT sign-in is unavailable. Sign in to Codex or the ChatGPT desktop app and try again.';
   let parsed;
   try {
     parsed = JSON.parse(readFile(authPath, 'utf8'));
   } catch {
-    throw new Error(
-      'ChatGPT sign-in is unavailable. Sign in to Codex or the ChatGPT desktop app and try again.',
-    );
+    throw new Error(unavailable);
   }
-  const token = String(parsed?.tokens?.access_token || '').trim();
-  if (!token) {
+  if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) {
+    throw new Error(unavailable);
+  }
+  const mode = String(parsed.auth_mode || '')
+    .trim()
+    .toLowerCase();
+  const chatGptMode = mode
+    ? mode === 'chatgpt' || mode === 'chatgptauthtokens'
+    : typeof parsed.OPENAI_API_KEY !== 'string';
+  const token = parsed.tokens?.access_token;
+  const refresh = parsed.tokens?.refresh_token;
+  if (
+    !chatGptMode ||
+    typeof token !== 'string' ||
+    !token.trim() ||
+    typeof refresh !== 'string' ||
+    !refresh.trim()
+  ) {
+    throw new Error(unavailable);
+  }
+
+  // This only checks token shape and expiry. OpenAI verifies the signature when
+  // minting the short-lived Realtime credential; we never modify auth.json.
+  const parts = token.split('.');
+  if (
+    parts.length !== 3 ||
+    parts.some((part) => !/^[A-Za-z0-9_-]+$/.test(part))
+  ) {
+    throw new Error(unavailable);
+  }
+  let payload;
+  try {
+    payload = JSON.parse(Buffer.from(parts[1], 'base64url').toString('utf8'));
+  } catch {
+    throw new Error(unavailable);
+  }
+  if (!payload || typeof payload !== 'object' || Array.isArray(payload)) {
+    throw new Error(unavailable);
+  }
+  let expiresAtMs;
+  if (Object.hasOwn(payload, 'exp')) {
+    if (typeof payload.exp !== 'number' || !Number.isFinite(payload.exp)) {
+      throw new Error(unavailable);
+    }
+    expiresAtMs = payload.exp * 1000;
+  } else {
+    try {
+      expiresAtMs = statFile(authPath).mtimeMs + 60 * 60 * 1000;
+    } catch {
+      throw new Error(unavailable);
+    }
+  }
+  if (!Number.isFinite(expiresAtMs) || expiresAtMs <= nowMs + 60_000) {
     throw new Error(
-      'ChatGPT sign-in is unavailable. Sign in to Codex or the ChatGPT desktop app and try again.',
+      'ChatGPT sign-in has expired. Run codex login and try again.',
     );
   }
   return token;

server/providers/openai/realtime.js

@@ -14,6 +14,7 @@ import {
 import { realtimeInstructions } from './instructions.js';
 import { GEV_REALTIME_TOOLS } from './tools.js';
 import {
+  preferCodexOAuth,
   readCodexOAuthAccessToken,
   startCodexChatGptLogin,
 } from './codex-auth.js';
@@ -174,6 +175,7 @@ function createRealtimeTokenHandler({
   fetchImpl = (...args) => fetch(...args),
   resolveApiKey = () => process.env.OPENAI_API_KEY,
   resolveOAuthAccessToken = () => readCodexOAuthAccessToken(),
+  environment = process.env,
   models = {},
 } = {}) {
   return async (req, res) => {
@@ -194,6 +196,28 @@ function createRealtimeTokenHandler({
       return;
     }
 
+    let oauthPinned;
+    try {
+      oauthPinned = preferCodexOAuth(environment);
+    } catch (error) {
+      res.statusCode = 503;
+      res.setHeader('Content-Type', 'application/json');
+      res.end(JSON.stringify({ error: error.message }));
+      return;
+    }
+    if (oauthPinned && authMode !== 'oauth') {
+      res.statusCode = 503;
+      res.setHeader('Content-Type', 'application/json');
+      res.end(
+        JSON.stringify({
+          error:
+            'ChatGPT OAuth is required by GEV_PREFER_CODEX_OAUTH. Select USE CHATGPT OAUTH in Provider Settings.',
+          code: 'CODEX_OAUTH_REQUIRED',
+        }),
+      );
+      return;
+    }
+
     // Opt-in per-IP throttle (GEV_RATELIMIT_OPENAI_PER_MIN). No-op when unset.
     if (!enforceOptInRateLimit(openAiRateLimiter(), req, res)) return;
 
@@ -332,6 +356,10 @@ function createRealtimeTokenHandler({
       // case where a bogus ?tier= was silently downgraded to standard.
       res.setHeader('X-GEV-Voice-Tier', tier);
       res.setHeader('X-GEV-Voice-Model', model);
+      res.setHeader(
+        'X-GEV-Voice-Auth',
+        authMode === 'oauth' ? 'codex-oauth' : 'env',
+      );
       if (requestedTier && !isKnownVoiceTier(requestedTier)) {
         res.setHeader('X-GEV-Voice-Tier-Fallback', '1');
       }