OpenAI Cuts GPT-5.6 Luna 80% to $0.20/$1.20 and Says GPT-5.6 Sol Autonomously Rewrote the Production Triton and Gluon Kernels That Paid For It

Simon Willison (on OpenAI's price-performance announcement)·high signalXBlueskyLinkedInCopy link

OpenAI announced on 2026-07-30 that GPT-5.6 Luna drops 80% to $0.20 input / $1.20 output per million tokens and Terra drops 20%, undercutting Gemini 3.1 Flash-Lite ($0.25/$1.50) and pricing Luna's input at one-fifth of Claude Haiku 4.5's $1. The stated mechanism is the interesting part: OpenAI used GPT-5.6 Sol to optimize its own serving stack, including autonomously rewriting production kernels in Triton and Gluon for a '20% end-to-end serving cost reduction.' Simon Willison immediately migrated his agent.datasette.io demo off Gemini 3.1 Flash-Lite to Luna on the strength of the new pricing.