load_artifact for not natively supported types shouldn't explode with "Unsupported MIME Type" #4028
Description
Describe the bug
If you persist an artifact that is not an image (CSV file in this example), following an example https://github.com/google/adk-python/blob/main/contributing/samples/generate_image/agent.py, load_artafact tool call for such an artifact is followed by
2025-12-26 12:54:15,962 - INFO - _client.py:1740 - HTTP Request: POST https://generativelanguage.googleapis.com/v1beta/models/gemini-3-pro-preview:generateContent "HTTP/1.1 400 Bad Request"
2025-12-26 12:54:16,027 - ERROR - adk_web_server.py:1509 - Error in event_generator: 400 INVALID_ARGUMENT. {'error': {'code': 400, 'message': 'Unsupported MIME type: application/csv', 'status': 'INVALID_ARGUMENT'}}
Traceback (most recent call last):
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/cli/adk_web_server.py", line 1499, in event_generator
async for event in agen:
...<7 lines>...
yield f"data: {sse_event}\n\n"
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/runners.py", line 505, in run_async
async for event in agen:
yield event
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/runners.py", line 493, in _run_with_trace
async for event in agen:
yield event
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/runners.py", line 722, in _exec_with_plugin
async for event in agen:
...<54 lines>...
yield (modified_event if modified_event else event)
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/runners.py", line 482, in execute
async for event in agen:
yield event
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/agents/base_agent.py", line 294, in run_async
async for event in agen:
yield event
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/agents/llm_agent.py", line 460, in _run_async_impl
async for event in agen:
...<5 lines>...
should_pause = True
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 370, in run_async
async for event in agen:
last_event = event
yield event
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 447, in _run_one_step_async
async for llm_response in agen:
...<13 lines>...
yield event
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 816, in _call_llm_async
async for event in agen:
yield event
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 800, in _call_llm_with_tracing
async for llm_response in agen:
...<12 lines>...
yield llm_response
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 1053, in _run_and_handle_error
raise model_error
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 1039, in _run_and_handle_error
async for response in agen:
yield response
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/models/google_llm.py", line 262, in generate_content_async
raise ce
File "miniforge3/envs/something/lib/python3.13/site-packages/google/adk/models/google_llm.py", line 241, in generate_content_async
response = await self.api_client.aio.models.generate_content(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...<3 lines>...
)
^
File "miniforge3/envs/something/lib/python3.13/site-packages/google/genai/models.py", line 7006, in generate_content
return await self._generate_content(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
model=model, contents=contents, config=parsed_config
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "miniforge3/envs/something/lib/python3.13/site-packages/google/genai/models.py", line 5824, in _generate_content
response = await self._api_client.async_request(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
'post', path, request_dict, http_options
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "miniforge3/envs/something/lib/python3.13/site-packages/google/genai/_api_client.py", line 1434, in async_request
result = await self._async_request(
^^^^^^^^^^^^^^^^^^^^^^^^^^
http_request=http_request, http_options=http_options, stream=False
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "miniforge3/envs/something/lib/python3.13/site-packages/google/genai/_api_client.py", line 1367, in _async_request
return await self._async_retry( # type: ignore[no-any-return]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
self._async_request_once, http_request, stream
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "miniforge3/envs/something/lib/python3.13/site-packages/tenacity/asyncio/__init__.py", line 111, in __call__
do = await self.iter(retry_state=retry_state)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "miniforge3/envs/something/lib/python3.13/site-packages/tenacity/asyncio/__init__.py", line 153, in iter
result = await action(retry_state)
^^^^^^^^^^^^^^^^^^^^^^^^^
File "miniforge3/envs/something/lib/python3.13/site-packages/tenacity/_utils.py", line 99, in inner
return call(*args, **kwargs)
File "miniforge3/envs/something/lib/python3.13/site-packages/tenacity/__init__.py", line 420, in exc_check
raise retry_exc.reraise()
~~~~~~~~~~~~~~~~~^^
File "miniforge3/envs/something/lib/python3.13/site-packages/tenacity/__init__.py", line 187, in reraise
raise self.last_attempt.result()
~~~~~~~~~~~~~~~~~~~~~~~~^^
File "miniforge3/envs/something/lib/python3.13/concurrent/futures/_base.py", line 449, in result
return self.__get_result()
~~~~~~~~~~~~~~~~~^^
File "miniforge3/envs/something/lib/python3.13/concurrent/futures/_base.py", line 401, in __get_result
raise self._exception
File "miniforge3/envs/something/lib/python3.13/site-packages/tenacity/asyncio/__init__.py", line 114, in __call__
result = await fn(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^
File "miniforge3/envs/something/lib/python3.13/site-packages/google/genai/_api_client.py", line 1347, in _async_request_once
await errors.APIError.raise_for_async_response(client_response)
File "miniforge3/envs/something/lib/python3.13/site-packages/google/genai/errors.py", line 203, in raise_for_async_response
await cls.raise_error_async(status_code, response_json, response)
File "miniforge3/envs/something/lib/python3.13/site-packages/google/genai/errors.py", line 225, in raise_error_async
raise ClientError(status_code, response_json, response)
google.genai.errors.ClientError: 400 INVALID_ARGUMENT. {'error': {'code': 400, 'message': 'Unsupported MIME type: application/csv', 'status': 'INVALID_ARGUMENT'}}
It would be much more helpful if artifacts with unsupported mime types were just made downloadable as raw files in the chat window instead.
To Reproduce
Store a file into "application/csv" in the artifacts storage and make ADK WEB to load it.
Expected behavior
Files that cannot be rendered should have a download button that functions the same way it currently does on the Artifacts tab.