OpenAI cuts GPT-5.6 Luna price by 80%, Terra by 20%

GPT-5.6 Luna now costs $0.20 per million input tokens and $1.20 per million output, an 80% drop; Terra is 20% cheaper at $2/$12. GPT-5.6 Sol gains a Fast API mode with 2.5x speed at 2x price. OpenAI credits Sol with optimizing inference, cutting serving costs by 20%.