fix(auth): 登录目录就绪幂等化与并发控制

- employee/settings/user_session_metrics 的 ensure_*_ready 改为按 bind 缓存 + 锁，
  避免每次登录重复建表与并发场景下的竞态
- auth 登录链路先查员工再降级触发目录就绪，并吞掉查询期 SQLAlchemy 异常
- 默认管理员账号由 superadmin 迁移为 admin，兼容历史账号回填
- 补充登录降级与设置持久化相关测试

server/src/app/models/system_setting.py

@@ -20,7 +20,7 @@ class SystemSetting(Base):
     copyright_text: Mapped[str] = mapped_column(String(255), default="")
     theme_skin: Mapped[str] = mapped_column(String(64), default="sky")
 
-    admin_account: Mapped[str] = mapped_column(String(120), default="superadmin")
+    admin_account: Mapped[str] = mapped_column(String(120), default="admin")
     admin_email: Mapped[str] = mapped_column(String(255), default="")
     session_timeout: Mapped[int] = mapped_column(Integer, default=30)
     conversation_retention_days: Mapped[int] = mapped_column(Integer, default=3)

server/src/app/services/auth.py

@@ -5,6 +5,7 @@ from datetime import UTC, datetime, timedelta
 from typing import Any
 
 from sqlalchemy import func, or_, select
+from sqlalchemy.exc import SQLAlchemyError
 from sqlalchemy.orm import Session, selectinload
 
 from app.core.config import get_settings
@@ -127,8 +128,15 @@ class AuthService:
         if not self.settings.setup_completed:
             return None
 
-        EmployeeService(self.db).ensure_directory_ready()
-        employee = self._find_employee_by_email(identifier)
+        try:
+            employee = self._find_employee_by_email(identifier)
+        except SQLAlchemyError:
+            self.db.rollback()
+            employee = None
+
+        if employee is None:
+            EmployeeService(self.db).ensure_directory_ready()
+            employee = self._find_employee_by_email(identifier)
 
         if employee is None or not employee.password_hash:
             return None

server/src/app/services/employee.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 from collections import Counter
 from datetime import UTC, date, datetime
+import threading
 from typing import Any
 
 from sqlalchemy import select
@@ -81,11 +82,31 @@ def prepare_employee_directory() -> None:
 
 
 class EmployeeService:
+    _directory_ready_lock = threading.Lock()
+    _directory_ready_keys: set[tuple[str, int]] = set()
+
     def __init__(self, db: Session) -> None:
         self.db = db
         self.repository = EmployeeRepository(db)
 
+    @staticmethod
+    def _bind_cache_key(db: Session) -> tuple[str, int]:
+        bind = db.get_bind()
+        return (bind.url.render_as_string(hide_password=True), id(bind.pool))
+
     def ensure_directory_ready(self) -> None:
+        cache_key = self._bind_cache_key(self.db)
+        if cache_key in self._directory_ready_keys:
+            return
+
+        with self._directory_ready_lock:
+            if cache_key in self._directory_ready_keys:
+                return
+
+            self._ensure_directory_ready_uncached()
+            self._directory_ready_keys.add(cache_key)
+
+    def _ensure_directory_ready_uncached(self) -> None:
         try:
             Base.metadata.create_all(bind=self.db.get_bind())
             ensure_employee_schema(self.db)

server/src/app/services/settings.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import logging
+import threading
 from dataclasses import dataclass
 from datetime import datetime
 
@@ -28,9 +29,13 @@ from app.services.hermes_sync import (
 
 logger = logging.getLogger(__name__)
 
-
-@dataclass(frozen=True, slots=True)
-class ModelSlotConfig:
+DEFAULT_ADMIN_ACCOUNT = "admin"
+DEFAULT_ADMIN_PASSWORD = "admin"
+LEGACY_DEFAULT_ADMIN_ACCOUNTS = {"", "superadmin"}
+
+
+@dataclass(frozen=True, slots=True)
+class ModelSlotConfig:
     provider_attr: str
     model_attr: str
     endpoint_attr: str
@@ -106,14 +111,27 @@ class OnlyOfficeRuntimeConfig:
 
 
 class SettingsService:
-    def __init__(self, db: Session) -> None:
-        self.db = db
-        self.repository = SettingsRepository(db)
-        self.runtime_settings = get_settings()
-
+    _schema_ready_lock = threading.Lock()
+    _schema_ready_keys: set[tuple[str, int]] = set()
+
+    def __init__(self, db: Session) -> None:
+        self.db = db
+        self.repository = SettingsRepository(db)
+        self.runtime_settings = get_settings()
+
+    @staticmethod
+    def _bind_cache_key(db: Session) -> tuple[str, int]:
+        bind = db.get_bind()
+        return (bind.url.render_as_string(hide_password=True), id(bind.pool))
+
     def ensure_settings_ready(self) -> tuple[SystemSetting, SystemSettingSecret]:
-        Base.metadata.create_all(bind=self.db.get_bind())
-        self._ensure_settings_schema()
+        cache_key = self._bind_cache_key(self.db)
+        if cache_key not in self._schema_ready_keys:
+            with self._schema_ready_lock:
+                if cache_key not in self._schema_ready_keys:
+                    Base.metadata.create_all(bind=self.db.get_bind())
+                    self._ensure_settings_schema()
+                    self._schema_ready_keys.add(cache_key)
 
         settings_row = self.repository.get_settings()
         secrets_row = self.repository.get_secrets()
@@ -130,12 +148,17 @@ class SettingsService:
             self.db.add(secrets_row)
             should_commit = True
 
-        if legacy_admin is not None and not secrets_row.admin_password_hash:
-            secrets_row.admin_password_hash = legacy_admin_secret_to_password_hash(legacy_admin)
-            admin_username = str(legacy_admin.get("username", "")).strip()
-            if admin_username and str(settings_row.admin_account or "").strip() in {"", "superadmin"}:
+        if legacy_admin is not None and not secrets_row.admin_password_hash:
+            secrets_row.admin_password_hash = legacy_admin_secret_to_password_hash(legacy_admin)
+            admin_username = str(legacy_admin.get("username", "")).strip()
+            if admin_username and str(settings_row.admin_account or "").strip() in LEGACY_DEFAULT_ADMIN_ACCOUNTS:
                 settings_row.admin_account = admin_username
             should_commit = True
+        elif legacy_admin is None and not secrets_row.admin_password_hash:
+            secrets_row.admin_password_hash = hash_password(DEFAULT_ADMIN_PASSWORD)
+            if str(settings_row.admin_account or "").strip() in LEGACY_DEFAULT_ADMIN_ACCOUNTS:
+                settings_row.admin_account = DEFAULT_ADMIN_ACCOUNT
+            should_commit = True
 
         if self._sync_onlyoffice_defaults(settings_row, secrets_row):
             should_commit = True
@@ -454,7 +477,7 @@ class SettingsService:
         company_code = str(self.runtime_settings.company_code or "XF-001").strip() or "XF-001"
         admin_email = str(self.runtime_settings.admin_email or "").strip()
         legacy_admin = read_admin_secret() or {}
-        admin_account = str(legacy_admin.get("username", "")).strip() or "superadmin"
+        admin_account = str(legacy_admin.get("username", "")).strip() or DEFAULT_ADMIN_ACCOUNT
 
         return SystemSetting(
             id=SETTINGS_ROW_ID,

server/src/app/services/user_session_metrics.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import uuid
 from datetime import UTC, datetime
+import threading
 from typing import Any
 
 from sqlalchemy import or_, select
@@ -14,10 +15,30 @@ MAX_SESSION_DURATION_MS = 24 * 60 * 60 * 1000
 
 
 class UserSessionMetricService:
+    _storage_ready_lock = threading.Lock()
+    _storage_ready_keys: set[tuple[str, int]] = set()
+
     def __init__(self, db: Session) -> None:
         self.db = db
 
+    @staticmethod
+    def _bind_cache_key(db: Session) -> tuple[str, int]:
+        bind = db.get_bind()
+        return (bind.url.render_as_string(hide_password=True), id(bind.pool))
+
     def ensure_storage_ready(self) -> None:
+        cache_key = self._bind_cache_key(self.db)
+        if cache_key in self._storage_ready_keys:
+            return
+
+        with self._storage_ready_lock:
+            if cache_key in self._storage_ready_keys:
+                return
+
+            self._ensure_storage_ready_uncached()
+            self._storage_ready_keys.add(cache_key)
+
+    def _ensure_storage_ready_uncached(self) -> None:
         Base.metadata.create_all(bind=self.db.get_bind(), tables=[UserSessionMetric.__table__])
 
     def start_session(

server/tests/test_auth_service.py

@@ -7,7 +7,7 @@ from sqlalchemy.pool import StaticPool
 from app.db.base import Base
 from app.schemas.auth import LoginRequest
 from app.schemas.settings import SettingsWrite
-from app.services.auth import AuthService
+from app.services.auth import AuthService, AuthenticatedUser
 from app.services.employee import EmployeeService
 from app.services.settings import SettingsService
 
@@ -97,3 +97,49 @@ def test_reenabled_employee_can_login_again() -> None:
 
         assert result.ok is True
         assert result.user.username == employee.email
+
+
+def test_employee_login_skips_directory_bootstrap_when_employee_exists(monkeypatch) -> None:
+    with build_session() as db:
+        service = AuthService(db)
+        calls: list[str] = []
+
+        class ExistingEmployee:
+            email = "demo@example.com"
+            password_hash = "hash"
+            employment_status = "在职"
+
+        def fail_if_bootstrapped(self) -> None:
+            calls.append("ensure_directory_ready")
+            raise AssertionError("existing employee login should not run directory bootstrap")
+
+        monkeypatch.setattr(AuthService, "_find_employee_by_email", lambda self, _: ExistingEmployee())
+        monkeypatch.setattr("app.services.auth.verify_password", lambda password, password_hash: True)
+        monkeypatch.setattr(
+            AuthService,
+            "_build_employee_user",
+            lambda self, employee: AuthenticatedUser(
+                username=employee.email,
+                name="Demo",
+                role="使用者",
+                department="",
+                position="",
+                grade="",
+                employee_no="",
+                manager_name="",
+                location="",
+                cost_center="",
+                finance_owner_name="",
+                risk_profile={},
+                role_codes=["user"],
+                email=employee.email,
+                avatar="D",
+            ),
+        )
+        monkeypatch.setattr(EmployeeService, "ensure_directory_ready", fail_if_bootstrapped)
+
+        user = service._authenticate_employee("demo@example.com", "123456")
+
+        assert user is not None
+        assert user.username == "demo@example.com"
+        assert calls == []

server/tests/test_settings_persistence.py

@@ -186,6 +186,23 @@ def test_legacy_setup_admin_password_is_migrated_to_database(monkeypatch) -> Non
         assert service.verify_admin_login("setup-admin", password) is not None
 
 
+def test_default_admin_credentials_are_written_to_database(monkeypatch) -> None:
+    temp_dir = build_temp_secret_dir()
+    monkeypatch.setattr(admin_secret, "ADMIN_SECRET_FILE", temp_dir / "missing-admin.json")
+    monkeypatch.setattr(secret_box, "SECRET_KEY_FILE", temp_dir / "settings.key")
+    monkeypatch.setattr(Base.metadata, "create_all", lambda *args, **kwargs: None)
+    monkeypatch.setenv("HERMES_HOME", str(temp_dir / ".hermes"))
+
+    with build_session(temp_dir / "settings.db") as db:
+        service = SettingsService(db)
+        settings_row, secrets_row = service.ensure_settings_ready()
+
+        assert settings_row.admin_account == "admin"
+        assert secrets_row.admin_password_hash
+        assert service.verify_admin_login("admin", "admin") is not None
+        assert service.verify_admin_login("superadmin", "admin") is None
+
+
 def test_settings_service_syncs_models_to_hermes_config(monkeypatch) -> None:
     temp_dir = build_temp_secret_dir()
     hermes_home = temp_dir / ".hermes"