We turned Pokemon Showdown into a GPU-parallel JAX battle sim: 22,320x speedup,

https://preview.redd.it/0j6ckc315qog1.png?width=1875&format=png&auto=webp&s=c6df71e03a1ec3f235346c5ee79e44b09fa3284a

Coding agents translated five RL environments into fast JAX/Rust for under $10 each — Pokemon Showdown to 22,320x, Pokemon TCG Pocket to 6.6x, HalfCheetah matching MJX, Pong 42x over PufferLib. No hand-written env code. Correctness verified by zero sim-to-sim gap (train in translation, eval in original). Paper: https://arxiv.org/abs/2603.12145