โจ OpenAI's GPT-5.6 is now ChatGPT's default โ Sol, Terra, and Luna explained
OpenAI shipped GPT-5.6 on July 9, making Sol the new flagship with an Ultra subagent mode, Terra a cost-efficient alternative at half the price, and Luna the speedy tier for quick tasks. It cleared a U.S. Commerce Department national security review before going live. The three-tier architecture is a new move for OpenAI โ which tier would you actually reach for?