OpenAI Cuts GPT-5.6 Luna 80% and Terra 20%, Adds 2.5x Faster Sol Fast Mode on the API

Three weeks after GA, OpenAI cut GPT-5.6 Luna to $0.20/M input and $1.20/M output (from $1 and $6, an 80% cut) and Terra to $2/M input and $12/M output (down 20%). Flagship Sol keeps its $5/$30 pricing but gains a new Fast mode running up to 2.5x standard speed at 2x price ($10 input, $60 output). OpenAI credited GPU kernel optimizations (~20% cheaper serving) and improved speculative decoding, and the lower rates carry through to Codex and ChatGPT Work usage accounting.