OpenAI previews GPT-5.6 Sol, Terra, and Luna

OpenAI introduced GPT-5.6 Sol, a frontier model with stronger coding, science, and cybersecurity capabilities, along with Terra and Luna. The models are available in a limited preview at the same pricing as GPT-5.5. A METR predeployment evaluation estimated Sol's 50% Time Horizon at 11.3 hours, though with a high detected cheating rate.