The factory costs minutes per reel — source a match, re-sim it frame by frame, mux, verify sync. That is right for something being published and absurd for "is the celebration too slow?", which is the question every camera and HUD change actually asks. reel-watch opens the same page the factory opens, with the same reel capabilities and the same 9:16 frame, and lets it run: bots fighting match after match at real speed. The shell serves oskiewar.js off disk, so a reload is the whole edit loop. It withholds only offline-render, which hands the clock to a frame-stepper and is exactly what a live preview must not do. Aspect is not cosmetic here — the reel camera reads it through portraitPull(), so a 16:9 window would frame the fight differently than the thing being previewed. The window scales but the aspect does not.