Claude was given an empty folder and built an operating system in eight days.
An Entropy engineer gave the new Claude Fable 5.2 an empty folder and asked for a prototype operating system. The model brought together more than 1,000 sub-agents who wrote, tested and tested code around the clock for eight days.
The result boots on a laptop. It has its own kernel, disk drivers, keyboard and network, file storage, windows, login screen, installer and built-in cloud.
Anthropic shared the benchmark when it released Fable 5.2 and Myth 5.2 on Monday. A team of 1,000 Fable agents also turned the proof of Fermat's Last Theorem into a form that the computer could check, in 30 hours. The anthropists' first attempt, with a man guiding it, lasted 11 days.
Fable 5.2 is open to all users. Myth 5.2, the same model with fewer cyber and biological safeguards, is only intended for vetted organizations.
Anthropic says Cloud now writes over 90% of the changes merged into its core code base, with human guidance.