OpenAI Releases GPT-5.6 Model Family: Sol, Terra, and Luna

OpenAI launched the GPT-5.6 family. Flagship Sol beats Claude Fable 5 on the Artificial Analysis Coding Agent Index at under half the cost. Terra matches GPT-5.5 at half the price, and Luna is 80% cheaper than Sol. Efficiency gains come from inference optimizations and the agentic harness: Sol autonomously rewrote production GPU kernels, cutting end-to-end serving costs by 20%. The post doesn't name the benchmarks for Terra and Luna, nor does it give absolute pricing for Sol.

Why it matters: OpenAI launches GPT-5.6 family: flagship Sol beats Claude Fable 5 on coding agent benchmarks at less than half the cost, with Terra and Luna targeting price-performance tiers. This is a top-tier model refresh with concrete comparisons and disclosed efficiency mechanisms — a sa...