diff --git a/src/daemon/spawner.py b/src/daemon/spawner.py
index 91580aa..27d35ff 100644
--- a/src/daemon/spawner.py
+++ b/src/daemon/spawner.py
@@ -149,6 +149,8 @@ class AgentSpawner:
 
         # session 注册表 {session_id: {...}}
         self._sessions: Dict[str, Dict[str, Any]] = {}
+        # B2 compact 等待计数器 {task_id: count}
+        self._compact_waits: Dict[str, int] = {}
 
     @property
     def active_sessions(self) -> Dict[str, Dict[str, Any]]:
@@ -511,8 +513,8 @@ curl -X POST http://{api_host}:{api_port}/api/projects/{project_id}/tasks/{task_
                         agent_id, session_id, monitor_timeout_count, self.max_monitor_timeouts)
             # 不递增 monitor_timeout_count，但最多额外等 max_monitor_timeouts 次
             # 用独立计数器防止无限等待
-            compact_wait_count = getattr(self, f"_compact_waits_{task_id}", 0) + 1
-            setattr(self, f"_compact_waits_{task_id}", compact_wait_count)
+            compact_wait_count = self._compact_waits.get(task_id, 0) + 1
+            self._compact_waits[task_id] = compact_wait_count
             if compact_wait_count >= self.max_monitor_timeouts:
                 logger.error("Agent %s max compact waits reached (session=%s, count=%d)",
                              agent_id, session_id, compact_wait_count)