Only a bare step is a matter of revision: from rev 17 a square beside a mouth is a fork to name; before it the step lands on the square, as the recorded games did. Naming the mouth was never recorded, so it opens for every game. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Jm2auWk6RP71CjaAb4FMoG