Posts on Ui Gate.

The in-chapter TOC needed live JavaScript. It still got a mockup first.

The captainrandom learning hub navigation retrofit ran five phases. Every one went through the UI gate — interactive approval mockup before production code. The most interesting case was P4: the subsystem's only client-side component, with a live IntersectionObserver scroll-spy in its mockup, still approved before a line of React was written.