fix: Fix BuiltInCodeExecutor so that it can support visualizations

Previously BuiltInCodeExecutor was missing the logic to save output files from executed code as artifacts, so images/visualizations wouldn't show up in the UI. This fix will iterate through all parts of the LlmResponse, and if any of them are images, it will save the image data using artifact_service (similar to what is done in VertexAICodeExecutor).

This fixes the backend, but there are still UI bugs that should be fixed -- events without content are currently ignored, so the image doesn't appear even though it is saved. We will add the UI fix in a separate change.

PiperOrigin-RevId: 822245140

src/google/adk/flows/llm_flows/_code_execution.py

@@ -19,6 +19,7 @@ from __future__ import annotations
 import base64
 import copy
 import dataclasses
+import datetime
 import os
 import re
 from typing import AsyncGenerator
@@ -275,6 +276,43 @@ async def _run_post_processor(
     return
 
   if isinstance(code_executor, BuiltInCodeExecutor):
+    event_actions = EventActions()
+
+    # If an image is generated, save it to the artifact service and add it to
+    # the event actions.
+    for part in llm_response.content.parts:
+      if part.inline_data and part.inline_data.mime_type.startswith('image/'):
+        if invocation_context.artifact_service is None:
+          raise ValueError('Artifact service is not initialized.')
+
+        if part.inline_data.display_name:
+          file_name = part.inline_data.display_name
+        else:
+          now = datetime.datetime.now().astimezone()
+          timestamp = now.strftime('%Y%m%d_%H%M%S')
+          file_extension = part.inline_data.mime_type.split('/')[-1]
+          file_name = f'{timestamp}.{file_extension}'
+
+        version = await invocation_context.artifact_service.save_artifact(
+            app_name=invocation_context.app_name,
+            user_id=invocation_context.user_id,
+            session_id=invocation_context.session.id,
+            filename=file_name,
+            artifact=types.Part.from_bytes(
+                data=part.inline_data.data,
+                mime_type=part.inline_data.mime_type,
+            ),
+        )
+        event_actions.artifact_delta[file_name] = version
+        part.inline_data = None
+        part.text = f'artifact: {file_name}'
+
+    yield Event(
+        invocation_id=invocation_context.invocation_id,
+        author=agent.name,
+        branch=invocation_context.branch,
+        actions=event_actions,
+    )
     return
 
   code_executor_context = CodeExecutorContext(invocation_context.session.state)

tests/unittests/flows/llm_flows/test_code_execution.py

@@ -0,0 +1,102 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Unit tests for Code Execution logic."""
+
+import datetime
+from unittest.mock import AsyncMock
+from unittest.mock import MagicMock
+from unittest.mock import patch
+
+from google.adk.agents.llm_agent import Agent
+from google.adk.code_executors.built_in_code_executor import BuiltInCodeExecutor
+from google.adk.flows.llm_flows._code_execution import response_processor
+from google.adk.models.llm_response import LlmResponse
+from google.genai import types
+import pytest
+
+from ... import testing_utils
+
+
+@pytest.mark.asyncio
+@patch('google.adk.flows.llm_flows._code_execution.datetime')
+async def test_builtin_code_executor_image_artifact_creation(mock_datetime):
+  """Test BuiltInCodeExecutor creates artifacts for images in response."""
+  mock_now = datetime.datetime(2025, 1, 1, 12, 0, 0)
+  mock_datetime.datetime.now.return_value.astimezone.return_value = mock_now
+  code_executor = BuiltInCodeExecutor()
+  agent = Agent(name='test_agent', code_executor=code_executor)
+  invocation_context = await testing_utils.create_invocation_context(
+      agent=agent, user_content='test message'
+  )
+  invocation_context.artifact_service = MagicMock()
+  invocation_context.artifact_service.save_artifact = AsyncMock(
+      return_value='v1'
+  )
+  llm_response = LlmResponse(
+      content=types.Content(
+          parts=[
+              types.Part(
+                  inline_data=types.Blob(
+                      mime_type='image/png',
+                      data=b'image1',
+                      display_name='image_1.png',
+                  )
+              ),
+              types.Part(text='this is text'),
+              types.Part(
+                  inline_data=types.Blob(mime_type='image/jpeg', data=b'image2')
+              ),
+          ]
+      )
+  )
+
+  events = []
+  async for event in response_processor.run_async(
+      invocation_context, llm_response
+  ):
+    events.append(event)
+
+  expected_timestamp = mock_now.strftime('%Y%m%d_%H%M%S')
+  expected_filename2 = f'{expected_timestamp}.jpeg'
+
+  assert invocation_context.artifact_service.save_artifact.call_count == 2
+  invocation_context.artifact_service.save_artifact.assert_any_call(
+      app_name=invocation_context.app_name,
+      user_id=invocation_context.user_id,
+      session_id=invocation_context.session.id,
+      filename='image_1.png',
+      artifact=types.Part.from_bytes(data=b'image1', mime_type='image/png'),
+  )
+  invocation_context.artifact_service.save_artifact.assert_any_call(
+      app_name=invocation_context.app_name,
+      user_id=invocation_context.user_id,
+      session_id=invocation_context.session.id,
+      filename=expected_filename2,
+      artifact=types.Part.from_bytes(data=b'image2', mime_type='image/jpeg'),
+  )
+
+  assert len(events) == 1
+  assert events[0].actions.artifact_delta == {
+      'image_1.png': 'v1',
+      expected_filename2: 'v1',
+  }
+  assert not events[0].content
+  assert llm_response.content is not None
+  assert len(llm_response.content.parts) == 3
+  assert llm_response.content.parts[0].text == 'artifact: image_1.png'
+  assert not llm_response.content.parts[0].inline_data
+  assert llm_response.content.parts[1].text == 'this is text'
+  assert llm_response.content.parts[2].text == f'artifact: {expected_filename2}'
+  assert not llm_response.content.parts[2].inline_data