Puts real design variations of one project file on the user's own localhost, behind a small card that flips them with the arrow keys, then keeps listening for their verdict. Use when the user wants design variations, alternatives, or directions to choose between; asks to try a different hero, layout, palette, section, or page; wants to design something new and compare a few takes; clicked the card (a vary, more, or done ask is queued); or wants to continue or finish a variate session. It works in an empty folder (serves a page, drafts four fresh designs) and in a real project (varies one file in place), on any stack. Not for a single change with one right answer, a refactor, or a non-visual edit: just edit the file for those.
