Messages API responses now report billed output tokens used for extended thinking.

Cost accounting gets a direct field for extended thinking inside the normal Messages API response.

For streaming builds, read the final message_delta event to capture the extended thinking token breakdown.

• Aug 25, 2026OpenAI models page removed visible model selection documentation text.
• Aug 25, 2026Anthropic model card removed Claude Fable 5 and Claude Mythos 5 selection guidance
• Aug 25, 2026OpenAI removed business pricing copy listing GPT-5.6 and GPT-Image-2 rates.

This is the world we build in. It moves this fast. We move with it.