OpenAI’s GPT-5.6 Sol, Terra, and Luna are now available in GitHub Copilot
TL;DR
OpenAI’s GPT-5.6 family started rolling out in GitHub Copilot on July 9, 2026. The three variants are Sol, Terra, and Luna, positioned for high-end reasoning, everyday coding, and cheaper fast assistance. Sol targets complex codebase reasoning and long-running agentic coding work. Terra is the balanced default for interactive and agentic coding. Luna is the lightweight, cost-efficient option for smaller tasks.
Nauti's Take
For small teams, Terra should be the first benchmark: same tickets, same repo context, same review workflow as before. Sol sounds like the model for long agent runs, but that is exactly where teams should first verify who can enable it, which budget limits apply, and whether the extra cost shows up in real code review quality.
Briefingshow
Copilot is becoming less of a single assistant and more of a model router for engineering teams. The useful shift is not the GPT-5.6 label itself, but the ability to choose between expensive, powerful, and good-enough-fast. For companies, governance matters: enabling Sol broadly may improve agentic work, but it also turns cost control into a real admin task.
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