细节优化——1

backend/app/api/v1/users.py

@@ -52,6 +52,17 @@ async def update_user(
     db_user = await user_crud.get_by_id(db, user_id)
     if not db_user:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="User not found")
+    if db_user.role.value == "ADMIN":
+        requested_role = user_in.role
+        requested_status = user_in.status
+        if user_in.is_active is not None:
+            requested_status = "ACTIVE" if user_in.is_active else "DISABLED"
+        will_leave_admin = requested_role is not None and requested_role != "ADMIN"
+        will_disable = requested_status is not None and requested_status != "ACTIVE"
+        if (will_leave_admin or will_disable) and db_user.status.value == "ACTIVE":
+            active_admins = await user_crud.count_active_admins(db)
+            if active_admins <= 1:
+                raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="至少保留一个管理员账号")
     user = await user_crud.update_user(db, db_user, user_in)
     return user
 
@@ -71,6 +82,10 @@ async def delete_user(
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="User not found")
     if db_user.id == current_user.id:
         raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="不允许删除自己")
+    if db_user.role.value == "ADMIN" and db_user.status.value == "ACTIVE":
+        active_admins = await user_crud.count_active_admins(db)
+        if active_admins <= 1:
+            raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="至少保留一个管理员账号")
     has_membership = await member_crud.user_has_memberships(db, db_user.id)
     if has_membership:
         raise HTTPException(