fix(BA-3806): use intersection operator for scaling group conflict detection (#7892)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: MinJuTur

changes/3806.fix.md

@@ -0,0 +1 @@
+Fix incorrect set operator for scaling group conflict validation in `modify_domain_node`

src/ai/backend/manager/services/domain/service.py

@@ -118,10 +118,10 @@ async def modify_domain_node(
         self, action: ModifyDomainNodeAction
     ) -> ModifyDomainNodeActionResult:
         if action.sgroups_to_add is not None and action.sgroups_to_remove is not None:
-            if union := action.sgroups_to_add | action.sgroups_to_remove:
+            if conflict := action.sgroups_to_add & action.sgroups_to_remove:
                 raise InvalidAPIParameters(
                     "Should be no scaling group names included in both `sgroups_to_add` and `sgroups_to_remove` "
-                    f"(sg:{union})."
+                    f"(sg:{conflict})."
                 )
 
         if action.user_info.role == UserRole.SUPERADMIN:

tests/unit/manager/services/test_domain.py

@@ -1001,3 +1001,57 @@ async def test_modify_domain_node_with_scaling_groups_to_remove(
 
         assert result.domain_data is not None
         mock_admin_repository.modify_domain_node_with_permissions_force.assert_called_once()
+
+    async def test_modify_domain_node_with_disjoint_scaling_groups_succeeds(
+        self,
+        service: DomainService,
+        mock_admin_repository: MagicMock,
+        superadmin_user: UserInfo,
+        sample_domain_data: DomainData,
+    ) -> None:
+        """Modify domain node with disjoint add/remove scaling groups should succeed."""
+        mock_admin_repository.modify_domain_node_with_permissions_force = AsyncMock(
+            return_value=sample_domain_data
+        )
+
+        action = ModifyDomainNodeAction(
+            user_info=superadmin_user,
+            updater=Updater(
+                spec=DomainNodeUpdaterSpec(),
+                pk_value="test-domain",
+            ),
+            sgroups_to_add={"sg1", "sg2"},
+            sgroups_to_remove={"sg3", "sg4"},  # No overlap
+        )
+
+        result = await service.modify_domain_node(action)
+
+        assert result.domain_data is not None
+        mock_admin_repository.modify_domain_node_with_permissions_force.assert_called_once()
+
+    async def test_modify_domain_node_with_empty_scaling_groups_succeeds(
+        self,
+        service: DomainService,
+        mock_admin_repository: MagicMock,
+        superadmin_user: UserInfo,
+        sample_domain_data: DomainData,
+    ) -> None:
+        """Modify domain node with both empty scaling groups should succeed."""
+        mock_admin_repository.modify_domain_node_with_permissions_force = AsyncMock(
+            return_value=sample_domain_data
+        )
+
+        action = ModifyDomainNodeAction(
+            user_info=superadmin_user,
+            updater=Updater(
+                spec=DomainNodeUpdaterSpec(),
+                pk_value="test-domain",
+            ),
+            sgroups_to_add=set(),
+            sgroups_to_remove=set(),
+        )
+
+        result = await service.modify_domain_node(action)
+
+        assert result.domain_data is not None
+        mock_admin_repository.modify_domain_node_with_permissions_force.assert_called_once()