fix(api): avoid mutating pipeline update payload

src/langbot/pkg/api/http/service/pipeline.py

@@ -113,14 +113,9 @@ class PipelineService:
         return pipeline_data['uuid']
 
     async def update_pipeline(self, pipeline_uuid: str, pipeline_data: dict) -> None:
-        if 'uuid' in pipeline_data:
-            del pipeline_data['uuid']
-        if 'for_version' in pipeline_data:
-            del pipeline_data['for_version']
-        if 'stages' in pipeline_data:
-            del pipeline_data['stages']
-        if 'is_default' in pipeline_data:
-            del pipeline_data['is_default']
+        pipeline_data = pipeline_data.copy()
+        for protected_field in ('uuid', 'for_version', 'stages', 'is_default'):
+            pipeline_data.pop(protected_field, None)
 
         await self.ap.persistence_mgr.execute_async(
             sqlalchemy.update(persistence_pipeline.LegacyPipeline)

tests/unit_tests/pipeline/test_pipeline_service.py

@@ -0,0 +1,43 @@
+from unittest.mock import AsyncMock, Mock
+
+import pytest
+
+from langbot.pkg.api.http.service.pipeline import PipelineService
+
+
+@pytest.mark.asyncio
+async def test_update_pipeline_filters_protected_fields_without_mutating_input(mock_app):
+    service = PipelineService(mock_app)
+    loaded_pipeline = Mock()
+    service.get_pipeline = AsyncMock(return_value=loaded_pipeline)
+
+    bot = Mock(uuid='bot-uuid')
+    bot_result = Mock(all=Mock(return_value=[bot]))
+    mock_app.persistence_mgr.execute_async = AsyncMock(side_effect=[None, bot_result])
+    mock_app.bot_service = Mock(update_bot=AsyncMock())
+    mock_app.pipeline_mgr = Mock(remove_pipeline=AsyncMock(), load_pipeline=AsyncMock())
+    mock_app.sess_mgr.session_list = []
+
+    pipeline_data = {
+        'uuid': 'caller-uuid',
+        'for_version': '1.0.0',
+        'stages': ['CallerStage'],
+        'is_default': True,
+        'name': 'Updated pipeline',
+    }
+    original_pipeline_data = pipeline_data.copy()
+
+    await service.update_pipeline('pipeline-uuid', pipeline_data)
+
+    assert pipeline_data == original_pipeline_data
+
+    update_stmt = mock_app.persistence_mgr.execute_async.await_args_list[0].args[0]
+    updated_fields = {getattr(field, 'key', str(field)) for field in update_stmt._values}
+    assert updated_fields == {'name'}
+
+    mock_app.bot_service.update_bot.assert_awaited_once_with(
+        'bot-uuid',
+        {'use_pipeline_name': 'Updated pipeline'},
+    )
+    mock_app.pipeline_mgr.remove_pipeline.assert_awaited_once_with('pipeline-uuid')
+    mock_app.pipeline_mgr.load_pipeline.assert_awaited_once_with(loaded_pipeline)