
The AI Extension Builder now runs on GPT-6 Luna
OpenAI released GPT-6 Sol and GPT-6 Luna on September 22, 2026, after GPT-6 Astra, the flagship of the family, earlier the same month. Luna is the smallest of the three. OpenAI describes it as its most efficient model for focused, high-volume tasks, and sells it at half the price of GPT-5.6 Luna, the model it replaces in OpenAI's own line-up.The next morning, we moved the AI Extension Builder to GPT-6 Luna, for every app, on the four moments where a model is at work: understanding your request, writing the code of the section, rewriting it when you ask for a change, and answering the questions you ask about what it built.
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