diff --git a/src/daemon/spawner.py b/src/daemon/spawner.py
index 23dd4b3..08345e5 100644
--- a/src/daemon/spawner.py
+++ b/src/daemon/spawner.py
@@ -764,7 +764,7 @@ curl -X POST http://{api_host}:{api_port}/api/projects/{project_id}/tasks/{task_
         """
         # ── 关键：手动 release counter（进程退出 = agent 空闲）──
         if self.counter:
-            self.counter.release(agent_id)
+            self.counter.release(agent_id, session_id or "main")
         # 旧 wrapped_on_complete 含 counter.release，不再使用，防止 double release
         on_complete = None