fix: reduce mysql connection pressure

db/task_db/task_model.py

@@ -10,6 +10,7 @@ from typing import Optional, Dict, List
 from pathlib import Path
 from enum import Enum
 import os
+from db.chat_log_db import _get_pooled_conn, _return_conn
 
 logger = logging.getLogger(__name__)
 _DB_TYPE = os.getenv("DB_TYPE", "sqlite").lower()
@@ -45,6 +46,19 @@ class TaskPriority(Enum):
     HIGH = "high"
     URGENT = "urgent"
 
+
+class _PooledMySQLConn:
+    """包装 pymysql 连接，close 时归还到共享连接池。"""
+
+    def __init__(self, conn):
+        self._conn = conn
+
+    def __getattr__(self, name):
+        return getattr(self._conn, name)
+
+    def close(self):
+        _return_conn(self._conn)
+
 class TaskManager:
     """任务管理器 - SQLite 存储"""
     
@@ -139,17 +153,7 @@ class TaskManager:
     def _get_conn(self):
         """获取数据库连接"""
         if _is_mysql():
-            import pymysql
-            return pymysql.connect(
-                host=_MYSQL_HOST,
-                port=_MYSQL_PORT,
-                user=_MYSQL_USER,
-                password=_MYSQL_PASSWORD,
-                database=_MYSQL_DATABASE,
-                charset="utf8mb4",
-                cursorclass=pymysql.cursors.DictCursor,
-                autocommit=False,
-            )
+            return _PooledMySQLConn(_get_pooled_conn())
         conn = sqlite3.connect(self.db_path)
         conn.row_factory = sqlite3.Row
         return conn