Show persistent timestamps for operation and teacher messages

tests/unit/coding-teacher.test.ts

@@ -164,6 +164,35 @@ async function fixture({ durableSource = false, sourceContext = context, liveMod
   };
 }
 describe('cloud coding teacher', () => {
+  it.each([false, true])('persists terminal times for local/cloud=%s replies across restart', async cloudTeacher => {
+    const f = await fixture({ cloudTeacher, mockCloud: cloudTeacher });
+    const topic = await f.service.create(f.scope, undefined, undefined, cloudTeacher ? 9 : undefined);
+    const id = '22222222-2222-4222-8222-222222222222';
+    await f.service.send(f.scope, topic.id, { requestId: id, text: '解释一下' });
+    const running = (await f.service.read(f.scope, topic.id)).requests[0];
+    expect(running.finishedAt).toBeUndefined();
+    const endingAfter = Date.now();
+    f.finish();
+    await vi.waitFor(async () => expect((await f.service.read(f.scope, topic.id)).requests[0].finishedAt).toBeTruthy());
+    const saved = (await f.service.read(f.scope, topic.id)).requests[0];
+    expect(saved.createdAt).toBe(running.createdAt);
+    expect(Date.parse(saved.finishedAt!)).toBeGreaterThanOrEqual(endingAfter);
+    expect(Date.parse(saved.finishedAt!)).toBeLessThanOrEqual(Date.now());
+    const restarted = await f.restart();
+    expect((await restarted.read(f.scope, topic.id)).requests[0]).toEqual(saved);
+  });
+  it.each(['cancelled', 'failed'] as const)('also saves the actual terminal time for %s replies', async status => {
+    const f = await fixture();
+    if (status === 'failed') f.run.mockRejectedValueOnce(new Error('failure'));
+    const topic = await f.service.create(f.scope);
+    const id = '22222222-2222-4222-8222-222222222222';
+    await f.service.send(f.scope, topic.id, { requestId: id, text: '解释一下' });
+    if (status === 'cancelled') await f.service.cancel(f.scope, topic.id, id);
+    await vi.waitFor(async () => expect((await f.service.read(f.scope, topic.id)).requests[0]).toMatchObject({ status, finishedAt: expect.any(String) }));
+    const saved = (await f.service.read(f.scope, topic.id)).requests[0];
+    expect((await (await f.restart()).read(f.scope, topic.id)).requests[0].finishedAt).toBe(saved.finishedAt);
+  });
+
   it('does not change the selected discussion when the companion polls an older topic', async () => {
     const f = await fixture();
     const old = await f.service.create(f.scope);