feat: include complete turn response in Agent.create_turn

[ehhuang]

Summary:

In #102, we made a turn's behavior more complete by automatically passing back the tool response and create another turn when client tool is used.

However, this creates a problem with the non-streaming API where the response object only contains information since the last tool call.

This PR is a hacky attemp to address this, by combining the Turn responses into one. I think ideally we should move all the loop logic to only be on the server side, where a turn would pause and the client SDK would pass tool reponses back to resume a turn.

I also changed it to not yield ToolResponseMessage but instead yield a proper ToolExecutionStep event so that it can be treated the same as server side tool execution in terms of logging. I.e. it now outputs:
"tool_execution> Tool:load_url Response:{"content": "\nToday Google announced that they have released the source code to PebbleOS. This is massive for Rebble, and will accelerate our" instead of "CustomTool> {"content": "\nToday Google announced that they have released the source code to PebbleOS. This is massive for Rebble, and will accelerate our efforts to "

Test Plan:

Added test in meta-llama/llama-stack#1078

Run a simple script with Agent and client tool. Observe the returned response has steps from both created turns.

Turn(
│ input_messages=[
│ │ UserMessage(
│ │ │ content='load https://llama-stack.readthedocs.io/en/latest/introduction/index.html and summarize it',
│ │ │ role='user',
│ │ │ context=None
│ │ )
│ ],
│ output_message=CompletionMessage(
│ │ content="The document from the given URL is about Google releasing the source code to PebbleOS, which is a significant development for Rebble. This allows Rebble to accelerate its efforts to produce new hardware. Rebble had been working on its own replacement firmware, RebbleOS, but the release of PebbleOS's source code will help Rebble to build a production-ready real-time OS for the Pebble.",
│ │ role='assistant',
│ │ stop_reason='end_of_turn',
│ │ tool_calls=[]
│ ),
│ session_id='dec1c6c0-ed9b-42c1-97d7-906871acd5ba',
│ started_at=datetime.datetime(2025, 2, 12, 16, 38, 14, 643186),
│ steps=[
│ │ InferenceStep(
│ │ │ api_model_response=CompletionMessage(
│ │ │ │ content='',
│ │ │ │ role='assistant',
│ │ │ │ stop_reason='end_of_turn',
│ │ │ │ tool_calls=[
│ │ │ │ │ ToolCall(
│ │ │ │ │ │ arguments={'url': 'https://llama-stack.readthedocs.io/en/latest/introduction/index.html'},
│ │ │ │ │ │ call_id='5d09151b-8a53-4292-be8d-f21e134d5142',
│ │ │ │ │ │ tool_name='load_url'
│ │ │ │ │ )
│ │ │ │ ]
│ │ │ ),
│ │ │ step_id='d724a238-d02b-4d77-a4bc-a978a54979c6',
│ │ │ step_type='inference',
│ │ │ turn_id='0496c654-cd02-48bb-a2ab-d1a0a5e91aba',
│ │ │ completed_at=datetime.datetime(2025, 2, 12, 16, 38, 15, 523310),
│ │ │ started_at=datetime.datetime(2025, 2, 12, 16, 38, 14, 654535)
│ │ ),
│ │ ToolExecutionStep(
│ │ │ step_id='49f19a5e-6a1e-4b1c-9232-fbafb82f2f89',
│ │ │ step_type='tool_execution',
│ │ │ tool_calls=[
│ │ │ │ ToolCall(
│ │ │ │ │ arguments={'url': 'https://llama-stack.readthedocs.io/en/latest/introduction/index.html'},
│ │ │ │ │ call_id='5d09151b-8a53-4292-be8d-f21e134d5142',
│ │ │ │ │ tool_name='load_url'
│ │ │ │ )
│ │ │ ],
│ │ │ tool_responses=[
│ │ │ │ ToolResponse(
│ │ │ │ │ call_id='5d09151b-8a53-4292-be8d-f21e134d5142',
│ │ │ │ │ content='{"content": "\nToday Google announced that they have released the source code to PebbleOS. This is massive for Rebble, and will accelerate our efforts to produce new hardware.\n\nPreviously, we have been working on our own replacement firmware: RebbleOS. As you can see by the commit history though, progress was slow. Building a production-ready realtime OS for the Pebble is no small feat, and although we were confident we’d get there given enough time, it was never our ideal path. Thanks to the hard work of many people both within Google and not, we finally have our hands on the original source code for PebbleOS. You can read Google’s blog post on this for even more information.\n\nThis does not mean we instantly have the ability to start developing updates for PebbleOS though, we first will need to spend some concentrated time getting it to build. But before we talk about that, let’s talk about Rebble itself.\n"}',
│ │ │ │ │ tool_name='load_url'
│ │ │ │ )
│ │ │ ],
│ │ │ turn_id='0496c654-cd02-48bb-a2ab-d1a0a5e91aba',
│ │ │ completed_at=datetime.datetime(2025, 2, 12, 16, 38, 15, 534830),
│ │ │ started_at=datetime.datetime(2025, 2, 12, 16, 38, 15, 534756)
│ │ ),
│ │ InferenceStep(
│ │ │ api_model_response=CompletionMessage(
│ │ │ │ content="The document from the given URL is about Google releasing the source code to PebbleOS, which is a significant development for Rebble. This allows Rebble to accelerate its efforts to produce new hardware. Rebble had been working on its own replacement firmware, RebbleOS, but the release of PebbleOS's source code will help Rebble to build a production-ready real-time OS for the Pebble.",
│ │ │ │ role='assistant',
│ │ │ │ stop_reason='end_of_turn',
│ │ │ │ tool_calls=[]
│ │ │ ),
│ │ │ step_id='5e6daa91-e689-4d7a-a7f9-d7c3da2eca5a',
│ │ │ step_type='inference',
│ │ │ turn_id='8f65d88d-7643-4dd7-acc7-48cd9e8aa449',
│ │ │ completed_at=datetime.datetime(2025, 2, 12, 16, 38, 16, 179107),
│ │ │ started_at=datetime.datetime(2025, 2, 12, 16, 38, 15, 561449)
│ │ )
│ ],
│ turn_id='0496c654-cd02-48bb-a2ab-d1a0a5e91aba',
│ completed_at=datetime.datetime(2025, 2, 12, 16, 38, 16, 191199),
│ output_attachments=[]
)

[hardikjshah]

Awesome, this makes it super consistent on server / client.