Initial support for tool_calls passthrough

[oseoin]

Proposed changes

Initially enure that for messages with null content and tool_calls present:

• null content is maintained
• tool_calls data is passed through

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have written my commit messages in the Conventional Commits format.
• I have read the CONTRIBUTING doc
• I have added tests (when possible) that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[ryan-surname-p]

will this work on response choices as well?

example response

{
  "id": "chatcmpl-abc123",
  "object": "chat.completion",
  "created": 1699896916,
  "model": "gpt-4o-mini",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": null,
        "tool_calls": [
          {
            "id": "call_abc123",
            "type": "function",
            "function": {
              "name": "get_current_weather",
              "arguments": "{\n\"location\": \"Boston, MA\"\n}"
            }
          }
        ]
      },
      "logprobs": null,
      "finish_reason": "tool_calls"
    }
  ],
  "usage": {
    "prompt_tokens": 82,
    "completion_tokens": 17,
    "total_tokens": 99,
    "completion_tokens_details": {
      "reasoning_tokens": 0,
      "accepted_prediction_tokens": 0,
      "rejected_prediction_tokens": 0
    }
  }
}

[oseoin]

@ryan-surname-p yes, the same Message class is used for both.

POST
http://localhost:8000/api/v1/execute/example/update-messages
user-agent:
httpyac
content-type:
multipart/form-data;boundary="boundary"
accept:
*/*
content-length:
1348
accept-encoding:
gzip, deflate, br
--boundary
Content-Disposition: form-data; name="response.parameters"
Content-Type: application/json

{ "modify": true, "add_system_prompt": true }
--boundary
Content-Disposition: form-data; name="metadata"
Content-Type: application/json

{  }
--boundary
Content-Disposition: form-data; name="response.choices"
Content-Type: application/json; charset=utf-8

{
  "id": "chatcmpl-abc123",
  "object": "chat.completion",
  "created": 1699896916,
  "model": "gpt-4o-mini",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": null,
        "tool_calls": [
          {
            "id": "call_abc123",
            "type": "function",
            "function": {
              "name": "get_current_weather",
              "arguments": "{\n\"location\": \"Boston, MA\"\n}"
            }
          }
        ]
      },
      "logprobs": null,
      "finish_reason": "tool_calls"
    },{
      "message": {
        "content": "Hello from system",
        "role": "assistant"
      }
    }
  ],
  "usage": {
    "prompt_tokens": 82,
    "completion_tokens": 17,
    "total_tokens": 99,
    "completion_tokens_details": {
      "reasoning_tokens": 0,
      "accepted_prediction_tokens": 0,
      "rejected_prediction_tokens": 0
    }
  }
}
--boundary--
HTTP/1.1
200
OK
date:
Wed, 16 Jul 2025 15:58:09 GMT
server:
uvicorn
content-type:
multipart/form-data;charset=utf-8;boundary="esOJMmZsk0GOGitgkvm3IUsaFb1oPQQqwuN73n6NyPOPDyp7tozbNjQIANeuzwL1"
content-encoding:
br
vary:
Accept-Encoding
transfer-encoding:
chunked
connection:
close
--esOJMmZsk0GOGitgkvm3IUsaFb1oPQQqwuN73n6NyPOPDyp7tozbNjQIANeuzwL1
Content-Disposition: form-data; name="response.choices"
Content-Type: application/json

{
    "choices": [
        {
            "message": {
                "content": null,
                "role": "assistant",
                "tool_calls": [
                    {
                        "id": "call_abc123",
                        "type": "function",
                        "function": {
                            "name": "get_current_weather",
                            "arguments": "{\n\"location\": \"Boston, MA\"\n}"
                        }
                    }
                ]
            }
        },
        {
            "message": {
                "content": "UpdateMessagesProcessor modified the output choice: Hello from system",
                "role": "assistant"
            }
        }
    ]
}
--esOJMmZsk0GOGitgkvm3IUsaFb1oPQQqwuN73n6NyPOPDyp7tozbNjQIANeuzwL1
Content-Disposition: form-data; name="metadata"
Content-Type: application/json

{"processor_id": "example:update-messages", "processor_version": "v1", "app_details": {"description": "UpdateMessagesProcessor is a simple example of a Starlette-based processor. "}}