进行了完整的视图拆分，同步了 merchant_ops 的修改

merchant_ops/services/authz.py

@@ -33,9 +33,7 @@ def get_active_staff_member(user):
 
 
 def require_active_staff_member(user):
-    """子客服接口鉴权：区分老板误入、未绑定、禁用、移除等场景。"""
-    if is_merchant_owner(user):
-        raise StaffAuthError(403, '您是商家老板，请使用商家端原接口')
+    """子客服接口鉴权：区分未绑定、禁用、移除等场景（已是商家老板也可担任其他店子客服）。"""
     member = MerchantStaffMember.query.filter(
         staff_user_id=user.UserUID,
     ).select_related('role').order_by('-id').first()
@@ -132,9 +130,21 @@ def resolve_owner_or_staff(request, perm_code=None):
     return 'staff', member.merchant_id, member, user.UserUID
 
 
-def assert_not_merchant_when_bind(user):
-    if is_merchant_owner(user):
-        raise StaffAuthError(403, '您已是商家，无法成为子客服')
+def assert_not_self_merchant_when_bind(user, invite_merchant_id):
+    """不能绑定为自己店铺的客服；可以是其他商家的子客服。"""
+    if invite_merchant_id is not None and str(user.UserUID) == str(invite_merchant_id):
+        raise StaffAuthError(403, '不能绑定为自己商家的客服')
+
+
+def assert_can_bind_staff(user, invite_merchant_id=None):
+    assert_not_self_merchant_when_bind(user, invite_merchant_id)
+    existing = MerchantStaffMember.query.filter(
+        staff_user_id=user.UserUID, status=MEMBER_STATUS_ACTIVE
+    ).first()
+    if existing:
+        if invite_merchant_id and str(existing.merchant_id) == str(invite_merchant_id):
+            raise StaffAuthError(400, '您已是该商家客服')
+        raise StaffAuthError(403, '您已绑定其他商家客服，请先联系原商家解除后再绑定')
 
 
 def assert_no_active_staff_when_merchant_register(user):
@@ -144,14 +154,6 @@ def assert_no_active_staff_when_merchant_register(user):
         raise StaffAuthError(403, '您当前是商家客服，请先联系商家解除后再认证商家')
 
 
-def assert_can_bind_staff(user):
-    assert_not_merchant_when_bind(user)
-    if MerchantStaffMember.query.filter(
-        staff_user_id=user.UserUID, status=MEMBER_STATUS_ACTIVE
-    ).exists():
-        raise StaffAuthError(403, '您已绑定商家客服，无法重复绑定')
-
-
 def get_owner_permissions():
     return list(OWNER_ALL_PERMISSIONS)