diff --git a/backend/app/core/database.py b/backend/app/core/database.py
index 271c54b..130594d 100644
--- a/backend/app/core/database.py
+++ b/backend/app/core/database.py
@@ -19,6 +19,12 @@ AsyncSessionLocal = async_sessionmaker(
 
 
 async def get_db() -> AsyncSession:
-    """FastAPI 依赖注入：每次请求获取一个数据库会话"""
+    """FastAPI 依赖注入：每次请求获取一个数据库会话（带事务安全兜底）"""
     async with AsyncSessionLocal() as session:
-        yield session
+        try:
+            yield session
+        except Exception:
+            await session.rollback()
+            raise
+        finally:
+            await session.close()