layouts/pro.json is the baked default; ~/.config/easel/layout.json overrides any key and is watched, so a save in an editor lands on the screen of the session already open. /layout shows the shape, /layout set changes one key from the prompt, /layout reset takes the override back, and /layout bake writes the shape into the package and commits that one file — the customisation becomes the code. The vocabulary is small and it is JSON: rows under the transcript, facts on the status line, the bar's shade, the prompt glyph, the separator. The data-sharing screen now stands in the middle of the window with the donkey over it, painted the way the interface paints him.