断点镜像状态标签回落：host-state 条目写 status 不是 goal_status

生产实弹：极小 goal 任务的 timeline 里 checkpoint goal_status 为
None——host.py 的任务条目只有 status（goal-running/goal-met），
没有 goal_status 键，镜像原样读 goal_status 永远是空。修法：
entry.get('goal_status') or entry.get('status')。轮次、thread_id、
state_sha 等关键字段不受影响（熔断只看轮次），纯标签 fidelity
修复；单测加 status-only 条目镜像断言。

cloud/tests/test_p0_three.py

@@ -240,6 +240,24 @@ class CheckpointMirrorTestCase(unittest.TestCase):
             conn.close()
         self.assertEqual(rows, [(1, "round"), (2, "round")])
 
+    def test_mirror_falls_back_to_status_label(self):
+        # host-state 条目写的是 status 不是 goal_status：实弹里
+        # 镜像到的 goal_status 全是 None，修法是取 status 回落。
+        with open(self.state_path, "w", encoding="utf-8") as fh:
+            json.dump({"version": 1, "tasks": {"T1": {
+                "goal_rounds_done": 2, "thread_id": "th2",
+                "status": "goal-met",
+                "goal_last_verify": ""}}}, fh)
+        self.assertEqual(self.worker._mirror_checkpoint_once(self.task), 2)
+        conn = sqlite3.connect(self.db_path)
+        try:
+            row = conn.execute(
+                "SELECT round_no, thread_id, goal_status"
+                " FROM task_checkpoints WHERE task_id = 'T1'").fetchone()
+        finally:
+            conn.close()
+        self.assertEqual(row, (2, "th2", "goal-met"))
+
     def test_rebuild_without_checkpoint_is_false(self):
         with open(self.state_path, "w", encoding="utf-8") as fh:
             json.dump({"version": 1, "tasks": {}}, fh)