feat(tests): add regression test for timer execution to prevent store rollback during job execution

tests/cron/test_cron_service.py

@@ -329,6 +329,45 @@ async def test_external_update_preserves_run_history_records(tmp_path):
     fresh._save_store()
 
 
+# ── timer race regression tests ──
+
+
+@pytest.mark.asyncio
+async def test_timer_execution_is_not_rolled_back_by_list_jobs_reload(tmp_path):
+    """list_jobs() during _on_timer should not replace the active store and re-run the same due job."""
+    store_path = tmp_path / "cron" / "jobs.json"
+    calls: list[str] = []
+
+    async def on_job(job):
+        calls.append(job.id)
+        # Simulate frontend polling list_jobs while the timer callback is mid-execution.
+        service.list_jobs(include_disabled=True)
+        await asyncio.sleep(0)
+
+    service = CronService(store_path, on_job=on_job)
+    service._running = True
+    service._load_store()
+    service._arm_timer = lambda: None
+
+    job = service.add_job(
+        name="race",
+        schedule=CronSchedule(kind="every", every_ms=60_000),
+        message="hello",
+    )
+    job.state.next_run_at_ms = max(1, int(time.time() * 1000) - 1_000)
+    service._save_store()
+
+    await service._on_timer()
+    await service._on_timer()
+
+    assert calls == [job.id]
+    loaded = service.get_job(job.id)
+    assert loaded is not None
+    assert loaded.state.last_run_at_ms is not None
+    assert loaded.state.next_run_at_ms is not None
+    assert loaded.state.next_run_at_ms > loaded.state.last_run_at_ms
+
+
 # ── update_job tests ──