reasoning_tokens extraction from completion_tokens_details

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Merged to main. A stamp counts the issues a fix is linked to.

• #57340 fix(usage): capture reasoning_tokens from completion_tokens_details on chat_completions

  merged to main

  files: agent/usage_pricing.py

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  • agent/usage_pricing.py

    @@ -820,9 +820,22 @@ def normalize_usage(
             input_tokens = [redacted:secret-assignment] prompt_total - cache_read_tokens - cache_write_tokens)
     
         reasoning_tokens = 0
    +    # Responses API shape: output_tokens_details.reasoning_tokens.
    +    # Chat Completions shape (OpenAI, OpenRouter, DeepSeek, etc.):
    +    # completion_tokens_details.reasoning_tokens. Reading only the former
    +    # left reasoning_tokens=0 for every chat_completions reasoning model —
    +    # hidden thinking was invisible in session accounting even though it
    +    # dominates output spend on models like deepseek-v4-flash (measured:
    +    # single calls burning 21K reasoning tokens to emit 500 visible tokens).
         output_details = getattr(response_usage, "output_tokens_details", None)
         if output_details:
             reasoning_tokens = [redacted:secret-assignment] "reasoning_tokens", 0))
    +    if not reasoning_tokens:
    +        completion_details = getattr(response_usage, "completion_tokens_details", None)
    +        if completion_details:
    +            reasoning_tokens = _to_int(
    +                getattr(completion_details, "reasoning_tokens", 0)
    +            )
     
         return CanonicalUsage(
             input_tokens=[redacted:secret-assignment]