diff --git a/scripts/migrate_business_from_sqlite.py b/scripts/migrate_business_from_sqlite.py
index 1fcb338f..252ee2d0 100644
--- a/scripts/migrate_business_from_sqlite.py
+++ b/scripts/migrate_business_from_sqlite.py
@@ -30,7 +30,7 @@ from typing import Any
 sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
 os.environ.setdefault("YUXI_SKIP_APP_INIT", "1")
 
-from sqlalchemy import Boolean, Column, DateTime, Integer, String, Text, create_engine, select, text
+from sqlalchemy import Column, DateTime, Integer, String, Text, create_engine, select, text
 from sqlalchemy.orm import declarative_base, sessionmaker
 
 from src import config
diff --git a/server/routers/auth_router.py b/server/routers/auth_router.py
index 4e75d456..59d7ba67 100644
--- a/server/routers/auth_router.py
+++ b/server/routers/auth_router.py
@@ -23,10 +23,7 @@ from server.utils.auth_utils import AuthUtils
 from server.utils.user_utils import generate_unique_user_id, validate_username, is_valid_phone_number
 from server.utils.common_utils import log_operation
 from src.storage.minio import aupload_file_to_minio
-from datetime import datetime as dt, UTC
-
-# 使用 naive datetime 以兼容 PostgreSQL TIMESTAMP WITHOUT TIME ZONE 列
-_utc_now = lambda: dt.now(UTC).replace(tzinfo=None)
+from src.utils.datetime_utils import utc_now_naive
 
 # 创建路由器
 auth = APIRouter(prefix="/auth", tags=["authentication"])
@@ -180,7 +177,7 @@ async def login_for_access_token(form_data: OAuth2PasswordRequestForm = Depends(
 
     # 登录成功，重置失败计数器
     user.reset_failed_login()
-    user.last_login = _utc_now()
+    user.last_login = utc_now_naive()
     await db.commit()
 
     # 生成访问令牌
@@ -270,7 +267,7 @@ async def initialize_admin(admin_data: InitializeAdmin, db: AsyncSession = Depen
             "password_hash": hashed_password,
             "role": "superadmin",
             "department_id": default_department.id,
-            "last_login": _utc_now(),
+            "last_login": utc_now_naive(),
         }
     )
 
@@ -679,7 +676,7 @@ async def delete_user(
     hash_suffix = hashlib.md5(user.user_id.encode()).hexdigest()[:4]
 
     user.is_deleted = 1
-    user.deleted_at = _utc_now()
+    user.deleted_at = utc_now_naive()
     user.username = f"已注销用户-{hash_suffix}"
     user.phone_number = None  # 清空手机号，释放该手机号供其他用户使用
     user.password_hash = "DELETED"  # 禁止登录
diff --git a/src/repositories/evaluation_repository.py b/src/repositories/evaluation_repository.py
index 03f61f74..c51d9cbe 100644
--- a/src/repositories/evaluation_repository.py
+++ b/src/repositories/evaluation_repository.py
@@ -4,8 +4,8 @@ from typing import Any
 
 from sqlalchemy import delete, select
 
-from src.storage.postgres.models_knowledge import EvaluationBenchmark, EvaluationResult, EvaluationResultDetail
 from src.storage.postgres.manager import pg_manager
+from src.storage.postgres.models_knowledge import EvaluationBenchmark, EvaluationResult, EvaluationResultDetail
 
 
 class EvaluationRepository:
diff --git a/src/repositories/knowledge_base_repository.py b/src/repositories/knowledge_base_repository.py
index 63b0c239..ef591750 100644
--- a/src/repositories/knowledge_base_repository.py
+++ b/src/repositories/knowledge_base_repository.py
@@ -4,8 +4,8 @@ from typing import Any
 
 from sqlalchemy import select
 
-from src.storage.postgres.models_knowledge import KnowledgeBase
 from src.storage.postgres.manager import pg_manager
+from src.storage.postgres.models_knowledge import KnowledgeBase
 
 
 class KnowledgeBaseRepository:
diff --git a/src/repositories/knowledge_file_repository.py b/src/repositories/knowledge_file_repository.py
index 5ac97362..520a5448 100644
--- a/src/repositories/knowledge_file_repository.py
+++ b/src/repositories/knowledge_file_repository.py
@@ -4,8 +4,8 @@ from typing import Any
 
 from sqlalchemy import select
 
-from src.storage.postgres.models_knowledge import KnowledgeFile
 from src.storage.postgres.manager import pg_manager
+from src.storage.postgres.models_knowledge import KnowledgeFile
 
 
 class KnowledgeFileRepository:
diff --git a/src/repositories/task_repository.py b/src/repositories/task_repository.py
index 8e8af1dd..5f089f64 100644
--- a/src/repositories/task_repository.py
+++ b/src/repositories/task_repository.py
@@ -43,4 +43,3 @@ class TaskRepository:
     async def delete_all(self) -> None:
         async with pg_manager.get_async_session_context() as session:
             await session.execute(delete(TaskRecord))
-
diff --git a/src/services/evaluation_service.py b/src/services/evaluation_service.py
index 6720facb..1280fac7 100644
--- a/src/services/evaluation_service.py
+++ b/src/services/evaluation_service.py
@@ -6,11 +6,11 @@ import uuid
 from datetime import datetime
 from typing import Any
 
-from src.services.task_service import TaskContext, tasker
 from src.knowledge import knowledge_base
 from src.models import select_model
 from src.repositories.evaluation_repository import EvaluationRepository
 from src.repositories.knowledge_base_repository import KnowledgeBaseRepository
+from src.services.task_service import TaskContext, tasker
 from src.utils import logger
 from src.utils.evaluation_metrics import EvaluationMetricsCalculator
 
diff --git a/src/services/task_service.py b/src/services/task_service.py
index a23b3dbd..d4741b6c 100644
--- a/src/services/task_service.py
+++ b/src/services/task_service.py
@@ -326,4 +326,3 @@ tasker = Tasker()
 
 
 __all__ = ["tasker", "TaskContext", "Tasker"]
-
diff --git a/src/storage/postgres/manager.py b/src/storage/postgres/manager.py
index 9a7647eb..49cd67ca 100644
--- a/src/storage/postgres/manager.py
+++ b/src/storage/postgres/manager.py
@@ -9,8 +9,8 @@ from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_asyn
 from sqlalchemy.orm import declarative_base
 
 from server.utils.singleton import SingletonMeta
-from src.storage.postgres.models_knowledge import Base as KnowledgeBase
 from src.storage.postgres.models_business import Base as BusinessBase
+from src.storage.postgres.models_knowledge import Base as KnowledgeBase
 from src.utils import logger
 
 # 合并两个 Base