diff --git a/tests/test_account_sensitive_fields.py b/tests/test_account_sensitive_fields.py
index 86203ff..957bc16 100644
--- a/tests/test_account_sensitive_fields.py
+++ b/tests/test_account_sensitive_fields.py
@@ -35,7 +35,7 @@ class TestAccountSensitiveFields:
     def test_sensitive_fields_are_hidden_by_default_even_for_admin(self):
         result = list_accounts(
             assigned_only=False,
-            tag=None,
+            tag="",
             has_cookie=False,
             search="",
             page=1,
@@ -45,6 +45,7 @@ class TestAccountSensitiveFields:
             current=self.admin,
         )
 
+        assert isinstance(result, dict)
         item = result["items"][0]
         assert item.password is None
         assert item.email is None
@@ -53,7 +54,7 @@ class TestAccountSensitiveFields:
     def test_admin_can_explicitly_request_sensitive_fields(self):
         result = list_accounts(
             assigned_only=False,
-            tag=None,
+            tag="",
             has_cookie=False,
             search="",
             page=1,
@@ -63,6 +64,7 @@ class TestAccountSensitiveFields:
             current=self.admin,
         )
 
+        assert isinstance(result, dict)
         item = result["items"][0]
         assert item.password == "account-password"
         assert item.email == "account@example.com"
diff --git a/tests/test_cookie_operations.py b/tests/test_cookie_operations.py
index 68ab5e2..78c1579 100644
--- a/tests/test_cookie_operations.py
+++ b/tests/test_cookie_operations.py
@@ -1,12 +1,13 @@
 import pytest
 from types import SimpleNamespace
 from unittest.mock import patch
+from typing import cast
 
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
 
 from web.backend.database import Base
-from web.backend.models import Account, LoginTask, User
+from web.backend.models import Account, LoginTask, ProxyConfig, User
 from web.backend.services.login_service import (
     LoginBatchRunner,
     cleanup_orphan_relogin_tasks,
@@ -137,6 +138,7 @@ class TestCookieOperation:
             current=admin,
         )
 
+        assert isinstance(result, dict)
         assert result["total"] == 1
         assert [item["id"] for item in result["items"]] == [self.owned_task.id]
 
@@ -200,7 +202,7 @@ class TestCookieOperation:
                 page=1,
                 page_size=20,
                 db=self.session,
-                current=no_permission_user,
+                current=cast(User, no_permission_user),
             )
 
     def test_relogin_failed_record_stays_visible_and_can_be_checked(self):
@@ -235,7 +237,7 @@ class TestCookieOperation:
         assert self.other_task.status == "success"
 
     def test_runner_copies_proxy_config_before_background_execution(self):
-        proxy = SimpleNamespace(
+        proxy = ProxyConfig(
             enabled=True,
             http="http://127.0.0.1:8080",
             https="",
diff --git a/tests/test_douyu_gold_recharge_channel.py b/tests/test_douyu_gold_recharge_channel.py
index 66d03d4..3337672 100644
--- a/tests/test_douyu_gold_recharge_channel.py
+++ b/tests/test_douyu_gold_recharge_channel.py
@@ -94,16 +94,18 @@ class TestDouyuGoldRechargeChannel:
         assert str(supplier.create_order.call_args.kwargs["pay_amount"]) == "10"
         self.session.refresh(self.task)
         assert self.task.status == "success"
-        assert self.task.result["recharge_channel"] == "supplier_api"
-        assert self.task.result["supplier_order_status"] == 2
-        assert self.task.result["buy_num"] == 10
-        assert self.task.result["out_order_id"] == expected_order_id
-        assert self.task.result["recharge_account"] == "罗炅729"
-        assert self.task.result["douyu_uid"] == "10001"
-        assert self.task.result["order_id"] == "supplier-001"
-        assert self.task.result["pay_amount"] == "10"
-        assert "pay_url" not in self.task.result
-        assert "sign" not in self.task.result["supplier_order"]
+        task_result = self.task.result
+        assert isinstance(task_result, dict)
+        assert task_result["recharge_channel"] == "supplier_api"
+        assert task_result["supplier_order_status"] == 2
+        assert task_result["buy_num"] == 10
+        assert task_result["out_order_id"] == expected_order_id
+        assert task_result["recharge_account"] == "罗炅729"
+        assert task_result["douyu_uid"] == "10001"
+        assert task_result["order_id"] == "supplier-001"
+        assert task_result["pay_amount"] == "10"
+        assert "pay_url" not in task_result
+        assert "sign" not in task_result["supplier_order"]
 
     @patch("web.backend.services.douyu_runner_gold.FishFinRechargeClient")
     def test_supplier_channel_rejects_account_without_nickname(self, client_class):
@@ -226,13 +228,14 @@ class TestDouyuGoldRechargeChannel:
         try:
             task = verify_session.get(DouyuTask, task_id)
             checked_login = verify_session.get(LoginTask, login_task_id)
+            assert task is not None
+            assert checked_login is not None
             assert task.status == "failed"
             assert "Cookie 已失效，请重新登录" in task.message
             assert checked_login.ck_check_status == "invalid"
-            assert (
-                checked_login.ck_check_result["message"]
-                == "鱼丸接口: 未登录；等级接口: 未登录"
-            )
+            check_result = checked_login.ck_check_result
+            assert isinstance(check_result, dict)
+            assert check_result["message"] == "鱼丸接口: 未登录；等级接口: 未登录"
         finally:
             verify_session.close()
 
@@ -273,8 +276,10 @@ class TestDouyuGoldRechargeChannel:
         assert self.task.message == "供应商直充成功（异步通知）"
         self.session.refresh(self.account)
         assert self.account.bind_status == "gold_recharged"
-        assert self.task.result["order_id"] == "supplier-001"
-        assert self.task.result["supplier_order_status"] == 2
+        task_result = self.task.result
+        assert isinstance(task_result, dict)
+        assert task_result["order_id"] == "supplier-001"
+        assert task_result["supplier_order_status"] == 2
         audit = (
             self.session.query(AuditLog)
             .filter(AuditLog.action == "recharge:douyu:callback")
diff --git a/tests/test_douyu_mobile_bind_skip.py b/tests/test_douyu_mobile_bind_skip.py
index 5fc64b3..cb62697 100644
--- a/tests/test_douyu_mobile_bind_skip.py
+++ b/tests/test_douyu_mobile_bind_skip.py
@@ -1,5 +1,6 @@
 from types import SimpleNamespace
 from unittest.mock import Mock
+from typing import Any, cast
 
 from core.douyu.login import DouyuLogin
 from core.douyu.login_api_wgapi import WgapiLoginAPI
@@ -9,13 +10,14 @@ class TestMobileBindSkip:
     def setup_method(self):
         self.login = DouyuLogin.__new__(DouyuLogin)
         self.login.api = WgapiLoginAPI()
-        self.login.account = SimpleNamespace(
-            username="test-user", password="test-password"
+        self.login.account = cast(
+            Any, SimpleNamespace(username="test-user", password="test-password")
         )
-        self.login._request_json = Mock()
+        self.request_json = Mock()
+        self.login.__dict__["_request_json"] = self.request_json
 
     def test_second_login_skips_mobile_bind_with_unique_key(self):
-        self.login._request_json.side_effect = [
+        self.request_json.side_effect = [
             {
                 "error": 130014,
                 "msg": "需要进行手机号绑定",
@@ -41,8 +43,8 @@ class TestMobileBindSkip:
         assert (
             login_url == "https://www.douyu.com/api/passport/login?code=callback-code"
         )
-        assert self.login._request_json.call_count == 2
-        skip_call = self.login._request_json.call_args_list[1]
+        assert self.request_json.call_count == 2
+        skip_call = self.request_json.call_args_list[1]
         assert skip_call.args[:3] == (
             "post",
             "https://passport.douyu.com/wgapi/member/passport/login",
@@ -55,7 +57,7 @@ class TestMobileBindSkip:
         }
 
     def test_second_login_preserves_remote_email_flow_without_unique_key(self):
-        self.login._request_json.return_value = {
+        self.request_json.return_value = {
             "error": 130014,
             "data": {"remoteLogin": {"code": "remote-code"}},
         }
@@ -69,4 +71,4 @@ class TestMobileBindSkip:
         )
 
         assert (next_step, remote_code) == ("remote_email", "remote-code")
-        assert self.login._request_json.call_count == 1
+        assert self.request_json.call_count == 1
diff --git a/tests/test_douyu_workbench_scopes.py b/tests/test_douyu_workbench_scopes.py
index 20a0df9..24e992a 100644
--- a/tests/test_douyu_workbench_scopes.py
+++ b/tests/test_douyu_workbench_scopes.py
@@ -1,5 +1,4 @@
 import pytest
-from types import SimpleNamespace
 
 from sqlalchemy import create_engine, event
 from sqlalchemy.orm import sessionmaker
@@ -54,12 +53,6 @@ class TestDouyuWorkbenchScope:
             )
         )
         self.session.commit()
-        self.current = SimpleNamespace(
-            id=self.user.id,
-            username=self.user.username,
-            role=self.user.role,
-            custom_permissions=None,
-        )
 
     def teardown_method(self):
         self.session.close()
@@ -72,12 +65,10 @@ class TestDouyuWorkbenchScope:
                 handbook_scope="elite", account_ids=[self.account.id]
             ),
             db=self.session,
-            current=self.current,
-        )
-        elite = list_workbench_accounts("elite", db=self.session, current=self.current)
-        esports = list_workbench_accounts(
-            "esports", db=self.session, current=self.current
+            current=self.user,
         )
+        elite = list_workbench_accounts("elite", db=self.session, current=self.user)
+        esports = list_workbench_accounts("esports", db=self.session, current=self.user)
         assert elite["account_ids"] == [self.account.id]
         assert esports["account_ids"] == []
         assert elite["configured"]
@@ -87,10 +78,10 @@ class TestDouyuWorkbenchScope:
         update_workbench_accounts(
             DouyuWorkbenchAccountsUpdate(handbook_scope="elite", account_ids=[]),
             db=self.session,
-            current=self.current,
+            current=self.user,
         )
         empty_elite = list_workbench_accounts(
-            "elite", db=self.session, current=self.current
+            "elite", db=self.session, current=self.user
         )
         assert empty_elite["account_ids"] == []
         assert empty_elite["configured"]
@@ -118,7 +109,7 @@ class TestDouyuWorkbenchScope:
             page=None,
             page_size=100,
             db=self.session,
-            current=self.current,
+            current=self.user,
         )
         esports = list_tasks(
             batch_id=None,
@@ -127,8 +118,10 @@ class TestDouyuWorkbenchScope:
             page=None,
             page_size=100,
             db=self.session,
-            current=self.current,
+            current=self.user,
         )
+        assert isinstance(elite, list)
+        assert isinstance(esports, list)
         assert {item.batch_id for item in elite} == {elite_batch}
         assert {item.batch_id for item in esports} == {esports_batch}
         assert {
@@ -182,6 +175,6 @@ class TestDouyuWorkbenchScope:
         )
         self.session.commit()
 
-        delete_account(self.account.id, db=self.session, current=self.current)
+        delete_account(self.account.id, db=self.session, current=self.user)
 
         assert self.session.query(DouyuWorkbenchAccount).count() == 0
diff --git a/tests/test_user_deletion.py b/tests/test_user_deletion.py
index a086d0a..c7a7bd5 100644
--- a/tests/test_user_deletion.py
+++ b/tests/test_user_deletion.py
@@ -1,6 +1,4 @@
 import pytest
-from types import SimpleNamespace
-
 from sqlalchemy import create_engine, event
 from sqlalchemy.orm import sessionmaker
 
@@ -53,11 +51,12 @@ class TestUserDeletion:
         result = delete_user(
             self.user.id,
             db=self.session,
-            current=SimpleNamespace(id=self.admin.id, username=self.admin.username),
+            current=self.admin,
         )
 
         deleted = self.session.get(User, self.user.id)
         account = self.session.query(Account).one()
+        assert deleted is not None
         assert result["success"]
         assert result["released_accounts"] == 1
         assert not deleted.is_active
@@ -74,7 +73,7 @@ class TestUserDeletion:
             delete_user(
                 self.user.id,
                 db=self.session,
-                current=SimpleNamespace(id=self.user.id, username=self.user.username),
+                current=self.user,
             )
 
     def test_rename_preserves_user_id_and_related_data(self):
@@ -82,12 +81,13 @@ class TestUserDeletion:
             self.user.id,
             UserRename(username="renamed-support"),
             db=self.session,
-            current=SimpleNamespace(id=self.admin.id, username=self.admin.username),
+            current=self.admin,
         )
 
         renamed = self.session.get(User, self.user.id)
         account = self.session.query(Account).one()
         task = self.session.query(LoginTask).one()
+        assert renamed is not None
         assert result.username == "renamed-support"
         assert renamed.id == self.user.id
         assert account.assigned_to == self.user.id
diff --git a/web/backend/schemas.py b/web/backend/schemas.py
index e582f62..388b488 100644
--- a/web/backend/schemas.py
+++ b/web/backend/schemas.py
@@ -41,6 +41,11 @@ def _ensure_tz(dt: Optional[datetime]) -> Optional[datetime]:
     return dt
 
 
+def _isoformat(dt: Optional[datetime]) -> str | None:
+    normalized = _ensure_tz(dt)
+    return normalized.isoformat() if normalized is not None else None
+
+
 # ---- 认证 ----
 class LoginRequest(BaseModel):
     username: str
@@ -75,7 +80,7 @@ class UserInfo(BaseModel):
             "role": self.role,
             "is_active": self.is_active,
             "remark": self.remark,
-            "created_at": _ensure_tz(self.created_at).isoformat() if self.created_at else None,
+            "created_at": _isoformat(self.created_at),
             "permissions": self.permissions,
             "custom_permissions": self.custom_permissions,
         }
@@ -108,6 +113,7 @@ class AccountImport(BaseModel):
     tag 为本次导入的统一标签兜底：某行未单独写标签时使用该值，
     行内第5列标签优先。
     """
+
     text: str
     tag: str = ""
 
@@ -123,6 +129,7 @@ class BatchAssign(BaseModel):
 
 class AccountBulkSelection(BaseModel):
     """批量操作选择范围：显式 ID 或当前筛选条件下全部账号。"""
+
     account_ids: list[int] = Field(default_factory=list)
     all_matching: bool = False
     search: str = ""
@@ -167,7 +174,7 @@ class AccountOut(BaseModel):
             "assigned_to": self.assigned_to,
             "assigned_username": self.assigned_username,
             "remark": self.remark,
-            "created_at": _ensure_tz(self.created_at).isoformat() if self.created_at else None,
+            "created_at": _isoformat(self.created_at),
         }
 
 
@@ -178,7 +185,9 @@ class LoginBatchRequest(BaseModel):
     max_total_time: float = 300  # 单账号登录总时长上限（秒），0=不限制
     concurrency: int = 3  # 并发数，1-10
     api_strategy: str = "wgapi"  # 接口策略: wgapi（新版）或 iframe（旧版备选）
-    mode: str = Field("login", pattern="^(login|check)$")  # login=登录取CK，check=账号状态检测
+    mode: str = Field(
+        "login", pattern="^(login|check)$"
+    )  # login=登录取CK，check=账号状态检测
 
 
 class CookieReloginRequest(BaseModel):
@@ -210,8 +219,8 @@ class LoginTaskOut(BaseModel):
             "cookie": self.cookie,
             "message": self.message,
             "created_by": self.created_by,
-            "created_at": _ensure_tz(self.created_at).isoformat() if self.created_at else None,
-            "finished_at": _ensure_tz(self.finished_at).isoformat() if self.finished_at else None,
+            "created_at": _isoformat(self.created_at),
+            "finished_at": _isoformat(self.finished_at),
         }
 
 
@@ -256,12 +265,14 @@ class AccountCheckBatchOut(BaseModel):
 # ---- 虎牙 ----
 class HuyaCookieImport(BaseModel):
     """批量导入虎牙 Cookie。支持纯 CK 或 账号----密码----CK。"""
+
     text: str
     tag: str = ""
 
 
 class HuyaPasswordLoginRequest(BaseModel):
     """虎牙账号 Web 密码登录并保存 Cookie（旧版）。"""
+
     username: str = Field(..., min_length=1, max_length=128)
     password: str = Field(..., min_length=1, max_length=128)
     tag: str = ""
@@ -270,6 +281,7 @@ class HuyaPasswordLoginRequest(BaseModel):
 
 class HuyaAppPasswordLoginRequest(BaseModel):
     """虎牙账号 App 协议密码登录并保存 Cookie（推荐）。"""
+
     username: str = Field(..., min_length=1, max_length=128)
     password: str = Field(..., min_length=1, max_length=128)
     tag: str = ""
@@ -278,12 +290,14 @@ class HuyaAppPasswordLoginRequest(BaseModel):
 
 class HuyaSmsCodeRequest(BaseModel):
     """发送虎牙短信验证码。"""
+
     phone: str = Field(..., min_length=5, max_length=32)
     cookie: str = ""
 
 
 class HuyaSmsLoginRequest(BaseModel):
     """提交虎牙短信验证码并保存 Cookie。"""
+
     authcode: str = Field(..., min_length=4, max_length=8)
     state: str = Field(..., min_length=1)
     phone: str = ""
@@ -292,6 +306,7 @@ class HuyaSmsLoginRequest(BaseModel):
 
 class HuyaAutoRegisterRequest(BaseModel):
     """虎牙自动注册批次。每行格式：手机号----短信查询URL。"""
+
     text: str = Field(..., min_length=1)
     tag: str = ""
     concurrency: int = Field(1, ge=1, le=5)
@@ -310,6 +325,7 @@ class HuyaAutoRegisterRetryRequest(BaseModel):
       - retry_failed: 只重试 error
       - all_unfinished: 失败+未完成都跑
     """
+
     mode: str = Field("continue", max_length=32)
     concurrency: Optional[int] = Field(None, ge=1, le=5)
     wait_seconds: Optional[float] = Field(None, ge=15, le=600)
@@ -382,12 +398,14 @@ class HuyaRegisterSuccessLogOut(BaseModel):
 
 class HuyaPasswordAccountImport(BaseModel):
     """导入虎牙账号密码，稍后再选择登录。"""
+
     text: str = Field(..., min_length=1)
     tag: str = ""
 
 
 class HuyaPasswordLoginSelectedRequest(BaseModel):
     """选择已导入的虎牙账号执行密码登录。"""
+
     account_ids: list[int] = Field(default_factory=list)
     all_matching: bool = False
     search: str = ""
@@ -399,6 +417,7 @@ class HuyaPasswordLoginSelectedRequest(BaseModel):
 
 class HuyaDeviceBindingsBatchDeleteRequest(BaseModel):
     """批量解绑设备：删除账号画像与 hydevice 指纹状态。"""
+
     accounts: list[str] = Field(..., min_length=1)
 
 
@@ -447,8 +466,8 @@ class HuyaAccountOut(BaseModel):
             "game_phone": self.game_phone,
             "assigned_to": self.assigned_to,
             "assigned_username": self.assigned_username,
-            "created_at": _ensure_tz(self.created_at).isoformat() if self.created_at else None,
-            "updated_at": _ensure_tz(self.updated_at).isoformat() if self.updated_at else None,
+            "created_at": _isoformat(self.created_at),
+            "updated_at": _isoformat(self.updated_at),
         }
 
 
@@ -468,7 +487,7 @@ class HuyaConfigOut(BaseModel):
             "outer_act_id": self.outer_act_id,
             "bind_act_id": self.bind_act_id,
             "pay_channel": self.pay_channel,
-            "updated_at": _ensure_tz(self.updated_at).isoformat() if self.updated_at else None,
+            "updated_at": _isoformat(self.updated_at),
         }
 
 
@@ -516,8 +535,8 @@ class HuyaTaskOut(BaseModel):
             "message": self.message,
             "result": self.result,
             "created_by": self.created_by,
-            "created_at": _ensure_tz(self.created_at).isoformat() if self.created_at else None,
-            "finished_at": _ensure_tz(self.finished_at).isoformat() if self.finished_at else None,
+            "created_at": _isoformat(self.created_at),
+            "finished_at": _isoformat(self.finished_at),
         }
 
 
@@ -541,7 +560,7 @@ class HuyaGoodsOut(BaseModel):
             "price": self.price,
             "remain_text": self.remain_text,
             "raw": self.raw,
-            "updated_at": _ensure_tz(self.updated_at).isoformat() if self.updated_at else None,
+            "updated_at": _isoformat(self.updated_at),
         }
 
 
@@ -577,7 +596,7 @@ class HuyaRechargeGoodsOut(BaseModel):
             "task_id": self.task_id,
             "task_name": self.task_name,
             "raw": self.raw,
-            "updated_at": _ensure_tz(self.updated_at).isoformat() if self.updated_at else None,
+            "updated_at": _isoformat(self.updated_at),
         }
 
 
@@ -634,7 +653,7 @@ class DouyuConfigOut(BaseModel):
             "gold_api_account_template_name": self.gold_api_account_template_name,
             "gift_id": self.gift_id,
             "skin_id": self.skin_id,
-            "updated_at": _ensure_tz(self.updated_at).isoformat() if self.updated_at else None,
+            "updated_at": _isoformat(self.updated_at),
         }
 
 
@@ -657,7 +676,9 @@ class DouyuConfigUpdate(BaseModel):
     xpd_act_id: Optional[str] = None
     xpd_rid: Optional[str] = None
     gold_pay_type: Optional[int] = Field(None, ge=1, le=9)
-    gold_recharge_channel: Optional[str] = Field(None, pattern="^(wechat_qr|supplier_api)$")
+    gold_recharge_channel: Optional[str] = Field(
+        None, pattern="^(wechat_qr|supplier_api)$"
+    )
     gold_api_product_id: Optional[str] = Field(None, max_length=128)
     gold_api_account_template_name: Optional[str] = Field(None, max_length=64)
     gift_id: Optional[str] = None
@@ -710,8 +731,8 @@ class DouyuTaskOut(BaseModel):
             "message": self.message,
             "result": self.result,
             "created_by": self.created_by,
-            "created_at": _ensure_tz(self.created_at).isoformat() if self.created_at else None,
-            "finished_at": _ensure_tz(self.finished_at).isoformat() if self.finished_at else None,
+            "created_at": _isoformat(self.created_at),
+            "finished_at": _isoformat(self.finished_at),
         }
 
 
@@ -735,7 +756,7 @@ class DouyuGoodsOut(BaseModel):
             "score": self.score,
             "status": self.status,
             "raw": self.raw,
-            "updated_at": _ensure_tz(self.updated_at).isoformat() if self.updated_at else None,
+            "updated_at": _isoformat(self.updated_at),
         }
 
 
@@ -794,7 +815,7 @@ class DouyuXpdGoodsOut(BaseModel):
             "category": self.category,
             "goods_left": self.goods_left,
             "raw": self.raw,
-            "updated_at": _ensure_tz(self.updated_at).isoformat() if self.updated_at else None,
+            "updated_at": _isoformat(self.updated_at),
         }
 
 
@@ -828,6 +849,7 @@ class ProxyConfigUpdate(BaseModel):
 # ---- 代理平台元信息 ----
 class PlatformFieldDef(BaseModel):
     """平台凭据字段定义。"""
+
     key: str
     label: str
     placeholder: str = ""
@@ -835,6 +857,7 @@ class PlatformFieldDef(BaseModel):
 
 class PlatformInfo(BaseModel):
     """平台元信息。"""
+
     name: str
     label: str
     credential_fields: list[PlatformFieldDef]