The new GPT-5.6 family: Luna, Terra, Sol

OpenAI's GPT-5.6 models (Luna $1/$6, Terra $2.50/$15, Sol $5/$30 per 1M tokens) launched with a 1M token context window and up to 128K output tokens. On Agents' Last Exam, Sol scores 53.6, outperforming Claude Fable 5 by 13.1 points at lower cost.