fix(startup): 收口 leader 失锁后的后台任务

- 为后台调度器注册失锁回调并只在 stop 成功后清空生命周期引用
- 停止调度器时移除定时 job，补充启动与任务协调器回归测试
- 降低多 worker 下重复调度风险，保持停机收口与统计聚合回归一致

tests/unit/test_task_coordinator.py

@@ -0,0 +1,106 @@
+from __future__ import annotations
+
+from typing import Any
+
+import pytest
+
+from src.utils.task_coordinator import StartupTaskCoordinator
+
+
+class _FakeRedis:
+    def __init__(self, eval_results: list[int] | None = None, set_result: bool = True) -> None:
+        self.eval_results = list(eval_results or [])
+        self.eval_calls: list[tuple[Any, ...]] = []
+        self.set_result = set_result
+        self.set_calls: list[tuple[Any, ...]] = []
+
+    async def eval(self, script: str, numkeys: int, *args: Any) -> int:
+        self.eval_calls.append((script, numkeys, *args))
+        if self.eval_results:
+            return self.eval_results.pop(0)
+        return 1
+
+    async def set(self, key: str, value: str, *, nx: bool, ex: int) -> bool:
+        self.set_calls.append((key, value, nx, ex))
+        return self.set_result
+
+
+class _FakeTask:
+    def __init__(self) -> None:
+        self.cancelled = False
+
+    def cancel(self) -> None:
+        self.cancelled = True
+
+
+@pytest.mark.asyncio
+async def test_startup_task_coordinator_acquire_starts_refresh_for_redis_lock(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    redis = _FakeRedis(eval_results=[1])
+    coordinator = StartupTaskCoordinator(redis)
+    started: list[tuple[str, int]] = []
+
+    monkeypatch.setattr(
+        coordinator,
+        "_start_refresh_task",
+        lambda name, ttl: started.append((name, ttl)),
+    )
+
+    acquired = await coordinator.acquire("maintenance_scheduler", ttl=120)
+
+    assert acquired is True
+    assert "maintenance_scheduler" in coordinator._tokens
+    assert started == [("maintenance_scheduler", 120)]
+
+
+@pytest.mark.asyncio
+async def test_startup_task_coordinator_refresh_lock_extends_matching_token() -> None:
+    redis = _FakeRedis(eval_results=[1])
+    coordinator = StartupTaskCoordinator(redis)
+    coordinator._tokens["maintenance_scheduler"] = "token-1"
+
+    refreshed = await coordinator._refresh_lock("maintenance_scheduler", ttl=180)
+
+    assert refreshed is True
+    assert len(redis.eval_calls) == 1
+    _script, numkeys, key, token, ttl = redis.eval_calls[0]
+    assert numkeys == 1
+    assert key == "task_lock:maintenance_scheduler"
+    assert token == "token-1"
+    assert ttl == 180
+
+
+@pytest.mark.asyncio
+async def test_startup_task_coordinator_release_cancels_refresh_task() -> None:
+    redis = _FakeRedis(eval_results=[1])
+    coordinator = StartupTaskCoordinator(redis)
+    coordinator._tokens["maintenance_scheduler"] = "token-1"
+    refresh_task = _FakeTask()
+    coordinator._refresh_tasks["maintenance_scheduler"] = refresh_task  # type: ignore[assignment]
+
+    await coordinator.release("maintenance_scheduler")
+
+    assert refresh_task.cancelled is True
+    assert "maintenance_scheduler" not in coordinator._refresh_tasks
+    assert "maintenance_scheduler" not in coordinator._tokens
+    assert len(redis.eval_calls) == 1
+    _script, numkeys, key, token = redis.eval_calls[0]
+    assert numkeys == 1
+    assert key == "task_lock:maintenance_scheduler"
+    assert token == "token-1"
+
+
+@pytest.mark.asyncio
+async def test_startup_task_coordinator_notify_lock_lost_runs_registered_callback() -> None:
+    coordinator = StartupTaskCoordinator()
+    called: list[str] = []
+
+    async def on_lock_lost(name: str) -> None:
+        called.append(name)
+
+    coordinator.register_lock_lost_callback("maintenance_scheduler", on_lock_lost)
+
+    await coordinator._notify_lock_lost("maintenance_scheduler")
+
+    assert called == ["maintenance_scheduler"]