update

backend/app/db.py

@@ -9,8 +9,11 @@ class Base(DeclarativeBase):
     """所有 ORM 模型的基类。"""
 
 
-# echo=False；生产环境可用连接池参数调优
-engine = create_async_engine(settings.database_url, echo=False, future=True)
+# echo=False；远程 PG 的空闲连接可能被中间层断开，pre_ping + recycle 自动剔除死连接
+engine = create_async_engine(
+    settings.database_url, echo=False, future=True,
+    pool_pre_ping=True, pool_recycle=1800,
+)
 async_session = async_sessionmaker(engine, expire_on_commit=False, class_=AsyncSession)