fix(ai): handle call arguments done on OpenAI-compatible endpoints

[williballenthin]

fix bug encountered when running GLM-4.7-Flash hosted by LM Studio, in which the provider sends tool call arguments via
response.function_call_arguments.done events instead of streaming them via response.function_call_arguments.delta events. The final response.output_item.done event then contains empty {} arguments. The code only handled delta events, so tool calls failed with validation errors like "must have required property 'command'".

Full disclosure, Opus triaged the bug and provided the fix (by adding logging statements to the req/resp to the upstream provider (LM Studio)). I'm happy to provide prompts/transcripts if you'd like, and acknowledge that I'm not an expert in Pi internals at this time.

Example output before fix:

and models.json config:

{
    "providers": {
      "lmstudio": {
        "baseUrl": "http://localhost:1234/v1",
        "apiKey": "unused",
        "api": "openai-responses",
        "models": [
          ...
          {
            "id": "glm-4.7-flash",
            "name": "glm-4.7-flash",
            "reasoning": true,
            "input": ["text"],
            "compat": {
              "supportsDeveloperRole": false,
              "thinkingFormat": "zai"
            },
            "cost": {"input": 0, "output": 0, "cacheRead": 0, "cacheWrite": 0},
            "contextWindow": 128000,
            "maxTokens": 32000
          }
        ]
      }
    }
  }

Other models, like Devstral Small 2, didn't show this issue.

[github-actions]

Hi @williballenthin, thanks for your interest in contributing!

We ask new contributors to open an issue first before submitting a PR. This helps us discuss the approach and avoid wasted effort.

Next steps:

1. Open an issue describing what you want to change and why (keep it concise, write in your human voice, AI slop will be closed)
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3. Then you can submit your PR

This PR will be closed automatically. See https://github.com/badlogic/pi-mono/blob/main/CONTRIBUTING.md for more details.

[badlogic]

Cheers, Opus did well :)