I had claude build a backdoor command port in the Godot application I'm working on. Using commands, Claude can interact with the screen, dump the node tree, and take screen shots. It works pretty well. Claude will definitely iterate over layout issues.

This is a good point. For anything without a DOM, screenshot diffing is basically your only option. Mozilla did this for Gecko layout regression testing 20+ years ago and it was remarkably effective. The interesting part now is that you can feed those screenshots to a vision model and get semantic analysis instead of just pixel diffing.