diff --git a/app/services/__pycache__/adapter_service.cpython-311.pyc b/app/services/__pycache__/adapter_service.cpython-311.pyc
index 95292a2..5ac9b46 100644
Binary files a/app/services/__pycache__/adapter_service.cpython-311.pyc and b/app/services/__pycache__/adapter_service.cpython-311.pyc differ
diff --git a/app/services/adapter_service.py b/app/services/adapter_service.py
index 2d57851..10d3002 100644
--- a/app/services/adapter_service.py
+++ b/app/services/adapter_service.py
@@ -13,25 +13,50 @@ from app.core.logger import info, error
 
 
 class AdapterService:
-    """适配器管理服务"""
+    """适配器管理服务（单例模式）
+    
+    确保整个应用中只有一个 AdapterService 实例，
+    避免重复创建导致适配器连接状态丢失。
+    """
+    
+    _instance: Optional['AdapterService'] = None
+    _lock = RLock()
+    
+    def __new__(cls) -> 'AdapterService':
+        if cls._instance is None:
+            with cls._lock:
+                if cls._instance is None:
+                    cls._instance = super().__new__(cls)
+                    cls._instance._initialized = False
+        return cls._instance
     
     def __init__(self):
-        self.lock = RLock()
-        
-        # 已注册的适配器工厂
-        self.factories: Dict[str, Callable[[], DataSourceAdapter]] = {}
-        
-        # 适配器配置
-        self.configs: Dict[str, dict] = {}
-        
-        # 当前激活的适配器实例
-        self.active_adapters: Dict[str, DataSourceAdapter] = {}
-        
-        # 适配器元数据
-        self.metadata: Dict[str, dict] = {}
+        # 避免重复初始化
+        if self._initialized:
+            return
         
-        # 注册内置适配器
-        self._register_builtin_adapters()
+        with self._lock:
+            if self._initialized:
+                return
+            
+            self.lock = RLock()
+            
+            # 已注册的适配器工厂
+            self.factories: Dict[str, Callable[[], DataSourceAdapter]] = {}
+            
+            # 适配器配置
+            self.configs: Dict[str, dict] = {}
+            
+            # 当前激活的适配器实例
+            self.active_adapters: Dict[str, DataSourceAdapter] = {}
+            
+            # 适配器元数据
+            self.metadata: Dict[str, dict] = {}
+            
+            # 注册内置适配器
+            self._register_builtin_adapters()
+            
+            self._initialized = True
     
     def _register_builtin_adapters(self):
         """注册内置适配器"""
@@ -155,12 +180,15 @@ class AdapterService:
             print(f"Using adapter: {active_name}")
             # 返回已激活的适配器实例
             if active_name in self.active_adapters:
+                print(f"Adapter {active_name} already connected, reusing...")
                 return self.active_adapters[active_name]
             
-            # 如果配置为启用但未激活，尝试连接
-            if active_name in self.configs and self.configs[active_name].get("enabled"):
-                # 启动异步连接（不等待）
-                asyncio.create_task(self._connect_adapter(active_name))
+            # 如果适配器已注册但未连接，尝试连接
+            # 检查适配器是否已注册（在 factories 中）
+            if active_name in self.factories:
+                print(f"Adapter {active_name} registered but not connected, connecting...")
+                # 注意：这里不直接调用异步方法，让调用方处理连接
+                # 返回 None 表示需要连接，由服务层调用 _connect_adapter
             
             # 如果没有激活的适配器，返回None
             return None