Fab Gym

▶ Play it live, no install: https://apoorvasinha183.github.io/fab-gym-site/ Fab Gym is a digital twin of a 1,043-machine wafer fab (the published SMT2020 testbed), presented by its cartoon robot CEO, Lou Latency. A fab cannot try a new rule on its real floor without risking weeks of output, so Fab Gym tests it first. Meta's models turn a plain-English what-if into an experiment, write dispatch rules as code, supervise the fab, play against you and guide you through it. A Rust simulator we wrote in this hackathon (about 0.03 s per simulated day, also in the browser through WebAssembly) scores every answer against today's rule on paired random days with 95% intervals, a Lean 4 referee checks every scored run, and a person signs. Play it in the browser with your own key, run it locally, load it as a Gymnasium RL environment, or walk the 3D fab in Godot with Lou, cinema included. We also report where the AI lost: on the full fab, no rule beat the fab's own.