any-llm version: latest (commit 2acea65)
Python Version: 3.12

Describe the bug

The Mistral provider fails with a TypeError when the user parameter is included in completion requests. This parameter is part of OpenAI's standard API (defined in CompletionParams) but is not supported by Mistral's API.

Error message:

TypeError: Chat.stream_async() got an unexpected keyword argument 'user'

Stack trace:

File "src/any_llm/providers/mistral/mistral.py", line 116, in _stream_completion_async
    mistral_stream = await self.client.chat.stream_async(model=model, messages=messages, **kwargs)
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: Chat.stream_async() got an unexpected keyword argument 'user'

Root cause:
MistralProvider._convert_completion_params() does not exclude the user parameter when converting CompletionParams to Mistral API format.

Current code (src/any_llm/providers/mistral/mistral.py, line 60-62):

converted_params = params.model_dump(
    exclude_none=True, exclude={"model_id", "messages", "response_format", "stream"}
)

The user parameter is defined in CompletionParams (line 129 in src/any_llm/types/completion.py) as part of the OpenAI-compatible interface, but Mistral's API doesn't support it.

Example w/ Code

Reproduction (Python):

from any_llm import completion

response = completion(
    model="mistral:mistral-small-latest",
    messages=[{"role": "user", "content": "Hello"}],
    user="user_123",  # This parameter causes the TypeError
    stream=True
)

Reproduction (HTTP/Gateway):

curl -X POST http://localhost:8000/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "mistral:mistral-small-latest",
    "messages": [{"role": "user", "content": "Hello"}],
    "user": "test_user_123",
    "stream": true
  }'

Expected Behavior:
The request should succeed with the user parameter automatically excluded.

Actual Behavior:
Raises TypeError: Chat.stream_async() got an unexpected keyword argument 'user'

Proposed Fix

Add "user" to the exclude list in src/any_llm/providers/mistral/mistral.py:61:

converted_params = params.model_dump(
    exclude_none=True, exclude={"model_id", "messages", "response_format", "stream", "user"}
)

Additional Context

Impact:

• Affects any application using any-llm directly OR through the gateway
• The user parameter is commonly used for tracking and rate limiting in production systems
• Gateway users are also affected since the gateway uses the core library internally
• Both streaming and non-streaming requests are affected

Related Code:

• CompletionParams definition: src/any_llm/types/completion.py:129-130
• Similar handling for reasoning_effort: src/any_llm/providers/mistral/mistral.py:71-72

Contribution

I have submitted a PR to fix this issue

Checklist:

• Searched existing issues for duplicates
• Verified bug exists in main branch (commit 2acea65)
• Provided clear reproduction steps
• Identified root cause and proposed fix