diff --git a/src/daemon/spawner.py b/src/daemon/spawner.py
index 8c6caf2..cda85ac 100644
--- a/src/daemon/spawner.py
+++ b/src/daemon/spawner.py
@@ -700,13 +700,15 @@ curl -X POST http://{api_host}:{api_port}/api/projects/{project_id}/tasks/{task_
         )
 
         # 续杯 spawn（counter 保持占用，直到 max_retries 或最终完成时 release）
+        # session 策略：原始是 main session (session_id=None) 时，retry 也用 main session
         try:
             await self.spawn_full_agent(
                 agent_id=agent_id,
                 message=message,
                 task_id=task_id,
                 on_complete=on_complete,
-                reuse_session_id=session_id,
+                use_main_session=(session_id is None),
+                reuse_session_id=session_id if session_id else None,
                 task_db_path=db_path,
             )
         except Exception: