GPT-5.6's 3 tiers reset enterprise AI inference costs in 2026
OpenAI's GPT-5.6 (Sol, Terra, Luna) went public on July 9, 2026, with Luna at $1/$6 per million tokens. We compare the new tiers to Claude Sonnet 5 and Gemini, and the levers that cut inference bills 60 to 80 percent.