OpenAI cuts GPT-5.6 Luna price 80%, Terra 20%, adds Sol Fast mode

OpenAI cut GPT-5.6 Luna pricing 80% to $0.20/M input and $1.20/M output tokens, and Terra 20% to $2/$12. GPT-5.6 Sol gains Fast mode in the API: up to 2.5x speed at 2x price with unchanged intelligence. The company credits GPT-5.6 Sol's efficiency for enabling the cuts.