OpenAI has begun a limited preview of GPT-5.6, its next-generation model series. The lineup splits into three named tiers: Sol, Terra, and Luna. Sol is the flagship. Terra targets everyday production work. Luna is the fast, low-cost option.
OpenAI is starting with a small group of trusted partners through the API and Codex. According to OpenAI post, they shared the models and plans with the U.S. government first. Broader access in ChatGPT, Codex, and the API is planned in the coming weeks.
The change is mostly structural. GPT-5.6 introduces tiered models, two new reasoning modes, and a heavier safety stack.
What is GPT-5.6?
GPT-5.6 is a family, not a single model. OpenAI also changed how it names releases. The number now marks the generation. The names mark durable capability tiers.
