fix(openai): honor absolute codex jwt expiry fallback

extensions/openai/openai-codex-device-code.test.ts

@@ -1,4 +1,5 @@
 import { describe, expect, it, vi } from "vitest";
+import { resolveCodexAccessTokenExpiry } from "./openai-codex-auth-identity.js";
 import { loginOpenAICodexDeviceCode } from "./openai-codex-device-code.js";
 
 function createJwt(payload: Record<string, unknown>): string {
@@ -88,6 +89,45 @@ describe("loginOpenAICodexDeviceCode", () => {
     expect(credentials.expires).toBeGreaterThan(Date.now());
   });
 
+  it("treats JWT-derived expiry fallback as an absolute timestamp", async () => {
+    const accessToken = createJwt({
+      exp: Math.floor(Date.now() / 1000) + 600,
+      "https://api.openai.com/auth": {
+        chatgpt_account_id: "acct_123",
+      },
+    });
+    const expectedExpiry = resolveCodexAccessTokenExpiry(accessToken);
+    const fetchMock = vi
+      .fn()
+      .mockResolvedValueOnce(
+        createJsonResponse({
+          device_auth_id: "device-auth-123",
+          user_code: "CODE-12345",
+          interval: "0",
+        }),
+      )
+      .mockResolvedValueOnce(
+        createJsonResponse({
+          authorization_code: "authorization-code-123",
+          code_verifier: "code-verifier-123",
+        }),
+      )
+      .mockResolvedValueOnce(
+        createJsonResponse({
+          access_token: accessToken,
+          refresh_token: "refresh-token-123",
+        }),
+      );
+
+    const credentials = await loginOpenAICodexDeviceCode({
+      fetchFn: fetchMock as typeof fetch,
+      onVerification: async () => {},
+    });
+
+    expect(expectedExpiry).toBeDefined();
+    expect(credentials.expires).toBe(expectedExpiry);
+  });
+
   it("surfaces user-code request failures", async () => {
     const fetchMock = vi.fn().mockResolvedValueOnce(new Response(null, { status: 503 }));
 

extensions/openai/openai-codex-device-code.ts

@@ -240,9 +240,11 @@ async function exchangeOpenAICodexDeviceCode(params: {
     throw new Error("OpenAI token exchange succeeded but did not return OAuth tokens.");
   }
 
+  const expiresInMs = normalizeTokenLifetimeMs(body?.expires_in);
   const expires =
-    Date.now() +
-    (normalizeTokenLifetimeMs(body?.expires_in) ?? resolveCodexAccessTokenExpiry(access) ?? 0);
+    expiresInMs !== undefined
+      ? Date.now() + expiresInMs
+      : (resolveCodexAccessTokenExpiry(access) ?? Date.now());
   const accountId =
     resolveCodexChatgptAccountId(access) ?? (idToken && resolveCodexChatgptAccountId(idToken));