refactor: 推进后端分层架构治理

app/db/uow.py

@@ -0,0 +1,36 @@
+"""SQLAlchemy 请求级事务适配器。"""
+
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.orm import Session
+
+
+class SqlAlchemyUnitOfWork:
+    """把同步 Session 的提交与回滚能力适配为应用层事务端口。"""
+
+    def __init__(self, session: Session) -> None:
+        """保存由请求依赖提供的同步数据库会话。"""
+        self._session = session
+
+    def commit(self) -> None:
+        """提交请求级事务。"""
+        self._session.commit()
+
+    def rollback(self) -> None:
+        """回滚请求级事务。"""
+        self._session.rollback()
+
+
+class SqlAlchemyAsyncUnitOfWork:
+    """把 AsyncSession 的提交与回滚能力适配为应用层事务端口。"""
+
+    def __init__(self, session: AsyncSession) -> None:
+        """保存由请求依赖提供的数据库会话。"""
+        self._session = session
+
+    async def commit(self) -> None:
+        """提交请求级事务。"""
+        await self._session.commit()
+
+    async def rollback(self) -> None:
+        """回滚请求级事务。"""
+        await self._session.rollback()