diff --git a/backend/app/hosts.py b/backend/app/hosts.py
index 26c80d5..0bb0a49 100644
--- a/backend/app/hosts.py
+++ b/backend/app/hosts.py
@@ -1,9 +1,10 @@
+from __future__ import annotations
 """主机注册表 - 管理多台 libvirt 宿主机"""
 import json
 import os
 import time
-import uuid
 import logging
+import uuid
 from typing import Optional
 from pydantic import BaseModel, Field
 from app.config import settings
diff --git a/backend/app/libvirt_conn.py b/backend/app/libvirt_conn.py
index 793e37e..08a2621 100644
--- a/backend/app/libvirt_conn.py
+++ b/backend/app/libvirt_conn.py
@@ -1,4 +1,5 @@
 """libvirt 多主机连接管理器"""
+from __future__ import annotations
 import libvirt
 from contextlib import contextmanager
 import logging