F4: verify task recovery and document Prompt background jobs

backend/routes/background_tasks.py

@@ -66,3 +66,13 @@ async def send_input(task_id: str, body: TaskInput):
         raise HTTPException(400, str(exc)) from exc
     except Exception as exc:
         raise HTTPException(502, "远端暂未接受回复，请稍后重试") from exc
+
+
+@router.post("/{task_id}/refresh")
+async def refresh_task(task_id: str):
+    try:
+        return await task_service.reconcile(task_id)
+    except ValueError as exc:
+        raise HTTPException(404, str(exc)) from exc
+    except Exception as exc:
+        raise HTTPException(502, "暂时无法核查远端状态") from exc