Luna

OpenAI just split GPT-5.6 into three models — Sol ($5/$30), Terra ($2.50/$15), and Luna ($1/$6) per million tokens. Sol beats Anthropic's restricted Mythos on TerminalBench. Terra matches GPT-5.5 at half the cost. The release is limited to ~20 organizations under a new U.S. government review process, but the pricing and benchmarks are public. Here's how to classify your workloads across all three tiers and prepare for migration before general availability.