feat: add OpenAI OAuth, strict model overrides, and Gmail pull mode

src/models/router.test.ts

@@ -438,4 +438,29 @@ describe('setClient and labels', () => {
     expect(newFastClient!.chat).toHaveBeenCalledTimes(1);
     expect(initialFastClient!.chat).toHaveBeenCalledTimes(1);
   });
+
+  it('strict tier mode disables fallback chain for that tier', async () => {
+    const failingDefault = {
+      chat: vi.fn().mockRejectedValue(new Error('primary failed')),
+    } as unknown as ModelClient;
+    const fallback = {
+      chat: vi.fn().mockResolvedValue({
+        content: 'fallback',
+        stopReason: 'end_turn',
+        usage: { inputTokens: 1, outputTokens: 1 },
+      }),
+    } as unknown as ModelClient;
+
+    const router = new ModelRouter({
+      default: failingDefault,
+      fallbackChain: [fallback],
+    });
+
+    router.setTierStrict('default', true);
+
+    await expect(router.chat({ messages: [{ role: 'user', content: 'Hi' }] }, 'default'))
+      .rejects.toThrow('primary failed');
+    expect(fallback.chat).not.toHaveBeenCalled();
+    expect(router.isTierStrict('default')).toBe(true);
+  });
 });