Surfaces
Loop board
The middle chip in a project window: the factory board, Backlog to Done.
The Loop chip opens the board: six columns, Backlog, Spec, Strategy, Build, Review, Done, with one card per piece and a hub bar across the top carrying Play Loop, which reads Pause Loop while the Loop plays. It is where you line work up and watch it move, one row of columns for the whole project rather than a tree of runs.
The columns, what Play and Pause actually start and stop, and how Backlog drafts work are covered in full on the board.