fix: 修复代码质量问题 - 更正异常处理和导入语句

Co-authored-by: Windpicker-owo <221029311+Windpicker-owo@users.noreply.github.com>

plugins/memory_graph_plugin/plugin.py

@@ -6,10 +6,12 @@ from typing import ClassVar
 
 from src.common.logger import get_logger
 from src.plugin_system import BasePlugin, register_plugin
-from src.plugin_system.base.component_types import ComponentInfo, ToolInfo
 
 logger = get_logger("memory_graph_plugin")
 
+# 用于存储后台任务引用
+_background_tasks = set()
+
 
 @register_plugin
 class MemoryGraphPlugin(BasePlugin):
@@ -60,6 +62,7 @@ class MemoryGraphPlugin(BasePlugin):
         """插件卸载时的回调"""
         try:
             import asyncio
+
             from src.memory_graph.manager_singleton import shutdown_memory_manager
 
             logger.info(f"{self.log_prefix} 正在关闭记忆系统...")
@@ -68,7 +71,10 @@ class MemoryGraphPlugin(BasePlugin):
             loop = asyncio.get_event_loop()
             if loop.is_running():
                 # 如果循环正在运行，创建任务
-                asyncio.create_task(shutdown_memory_manager())
+                task = asyncio.create_task(shutdown_memory_manager())
+                # 存储引用以防止任务被垃圾回收
+                _background_tasks.add(task)
+                task.add_done_callback(_background_tasks.discard)
             else:
                 # 如果循环未运行，直接运行
                 loop.run_until_complete(shutdown_memory_manager())