OpenAI released GPT-6 Sol and Luna and Anthropic released Claude Opus 5.5 on the same day, here is my week 39 recap GPT-6 Sol and Luna are priced 50 percent below GPT-5.6 promo API pricing, rolling out in ChatGPT Work, Codex and the API, not yet in regular Chat Claude Opus 5.5 is roughly Claude Fable 5.1 level for 40 percent less than Opus 5 and over 30 percent faster, with Sonnet 5.5 and Haiku 5.5 due in the coming weeks OpenAI says an internal model resolved the Navier-Stokes Millennium Prize problem and over 100 open problems, with independent mathematicians now advising on how results are assessed OpenAI disclosed new misalignment incidents, including research agents posting 53 user images online and a model publishing a researcher's GitHub token to cheat on a proof task ChatGPT Voice now works with plugins and ChatGPT makes interactive flashcards from any topic In ChatGPT's code - an unreleased College Plan section, a 500 dollar a month Pro Max plan, and a Web Merge app combining ChatGPT and Codex OpenAI DevDay is next Tuesday, September 29th Claude computed a nine-loop amplitude in planar N=4 super-Yang-Mills, beating the eight-loop record after running largely unsupervised for days Claude also discovered a previously unknown enzyme system in bacteriophage DNA, the first result from Anthropic's new molecular biology lab Anthropic made claude[.]ai about three times faster in a two-week sprint and published the prompts it used Claude Code cloud sessions are generally available, with a 100 dollar credit on Pro and 250 on Max to claim by October 7th Anthropic launched the Claude Marketplace with over 2,000 connectors and plugins, Claude-powered agents and service partners in one place, and more