GPT-5.6 Luna is the lower-cost tier of OpenAI’s GPT-5.6 family, alongside Terra and the frontier tier Sol. In this corpus it is the model Sol autonomously post-trained in July 2026, and the one whose price fell 80% three weeks later on kernels Sol rewrote, with OpenAI claiming it beats Claude Fable 5 on Agents’ Last Exam at 99% lower cost per task.
AISystem
GPT-5.6 Luna
OpenAI's lower-cost GPT-5.6 tier, autonomously post-trained by Sol and then cut 80% in price on kernels Sol rewrote.
Sources
Attribution and reporting linked by this record; links do not imply independent verification.
- Welcome to July 30, 2026 (theinnermostloop.substack.com)
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