Reasoning Field Standardization

Issue

DeepSeek uses "reasoning_content" field while OpenAI uses "reasoning" field in their chat completion streaming responses. This inconsistency caused confusion about what field name to use in the g4f Interference API.

Decision

Standardized on OpenAI's "reasoning" field format for API output while maintaining input compatibility.

Rationale

1. OpenAI Compatibility: OpenAI is the de facto standard for chat completion APIs
2. Ecosystem Compatibility: Most tools and libraries expect OpenAI format
3. Consistency: Provides a unified output format regardless of the underlying provider
4. Backward Compatibility: Input parsing continues to accept both formats

Implementation

Input Format Support (Unchanged)

The system continues to accept both input formats in OpenaiTemplate.py:

reasoning_content = choice.get("delta", {}).get("reasoning_content", choice.get("delta", {}).get("reasoning"))

Output Format Standardization (Changed)

• Streaming Delta: Uses reasoning field (OpenAI format)
• Non-streaming Message: Uses reasoning field (OpenAI format)
• API Responses: Should use standard OpenAI streaming format

Example Output Formats

Streaming Response (OpenAI Compatible)

{
  "id": "chatcmpl-example",
  "object": "chat.completion.chunk",
  "choices": [{
    "index": 0,
    "delta": {
      "role": "assistant",
      "reasoning": "I need to think about this step by step..."
    },
    "finish_reason": null
  }]
}

Non-streaming Response

{
  "choices": [{
    "message": {
      "role": "assistant",
      "content": "Here's my answer",
      "reasoning": "My reasoning process was..."
    }
  }]
}

Files Changed

• g4f/client/stubs.py: Updated to use reasoning field instead of reasoning_content

Testing

• Added comprehensive tests for format standardization
• Verified input compatibility with both OpenAI and DeepSeek formats
• Confirmed no regressions in existing functionality