OpenAI-compatible chat completions over x402, answered by Claude Sonnet 4.6 — send a messages array and get an assistant reply for Q&A, reasoning, agent planning, coding help, summarization, extraction, classification, and chatbot responses. The body is OpenAI chat.completions-shaped ({model?, messages:[{role,content}], max_tokens?, temperature?}) and the response is a chat.completion object. Flat $0.06 per call; inputs are capped at ~6KB and max_tokens at 1024; streaming is not supported in v1.