x.comthread

Brandon Wie (@BrandonWie) on X

A Twitter/X thread announcing an open-source framework for reinforcement-learning training of models that runs inside the actual agent harnesses practitioners use — Claude Code, Codex, and OpenCode — rather than a synthetic training environment. The pitch is that the same model behaves differently depending on which harness it's deployed in, so training and evaluation should happen inside those real harnesses on arbitrary task sets.