OpenAI launches GPT-5.6 family with Sol, Terra, Luna

GPT-5.6 comes in three sizes: Luna ($1/$6 per 1M tokens), Terra ($2.50/$15), and Sol ($5/$30). All have a 1M token context window and 128k output. On Agents' Last Exam, Sol scored 53.6, beating Claude Fable 5 by 13.1 points, while Terra and Luna outperform at lower costs.