diff --git a/src/daemon/spawner.py b/src/daemon/spawner.py
index 6119c29..c842845 100644
--- a/src/daemon/spawner.py
+++ b/src/daemon/spawner.py
@@ -243,17 +243,25 @@ curl -X POST http://{self.api_host}:{self.api_port}/api/projects/{project_id}/ta
         on_complete: Optional[Any] = None,
         use_main_session: bool = False,
         task_db_path: Optional[Path] = None,
+        reuse_session_id: Optional[str] = None,
     ) -> str:
         """Spawn Full Agent（异步非阻塞）
 
         Args:
             on_complete: async callback(agent_id, outcome) — Agent 完成后调用
             use_main_session: True = 投递到主 Agent session（不传 --session-id）
+            reuse_session_id: 传入指定 session-id 复用（用于续杯）
 
         Returns:
             session_id
         """
-        session_id = None if use_main_session else str(uuid.uuid4())
+        # Session 策略：main > reuse > new
+        if use_main_session:
+            session_id = None
+        elif reuse_session_id:
+            session_id = reuse_session_id
+        else:
+            session_id = str(uuid.uuid4())
 
         if self.dry_run:
             logger.info("[DRY RUN] Would spawn agent %s (session=%s)", agent_id, session_id or "main")
@@ -552,7 +560,7 @@ curl -X POST http://{api_host}:{api_port}/api/projects/{project_id}/tasks/{task_
                 message=message,
                 task_id=task_id,
                 on_complete=on_complete,
-                use_main_session=(session_id is None),
+                reuse_session_id=session_id,
                 task_db_path=db_path,
             )
         except Exception: