OpenAI ships GPT-5.6 with Sol/Terra/Luna tiers and effort controls
OpenAI launched GPT-5.6 as a three-model family (Sol, Terra, Luna) with Max and Ultra effort levels, cache-write pricing, and a 90% cache-read discount. Pricing spans $1–$5 per million tokens. Independent evals put Sol near frontier coding-agent performance at roughly one-third the cost of Claude Fable 5, with a ~500 Elo gain on presentation tasks. Early reports flag instruction-following regressions and jailbreak concerns.
Tiered effort levels turn model selection into a per-call cost/quality knob — plan routing logic, not just a default model. The cache-write pricing changes prompt architecture math; long system prompts get materially cheaper if you actually pin them.