OpenAI launches cheaper GPT-6 Sol and Luna models

OpenAI expanded the GPT-6 family on September 22, 2026 with GPT-6 Sol and GPT-6 Luna, cheaper models that it says carry much of GPT-6 Astra's capability. API docs list Sol at $2 per million input tokens and $10 per million output tokens for complex coding and agentic work, and Luna at $0.10 and $0.50 for high-volume tasks. Both are in the API and in ChatGPT Work and Codex for paid plans; Luna is also rolling to Free and Go users, and GitHub added both models to Copilot.