The IO that drives audience-mode scroll navigation kept firing during the layout transition into presenter mode: as slides shifted between slot states the IO saw them passing through the host's viewport and sent navigate.scroll for each one, marching currentIndex through every slide before settling on whichever fired last. Gate fireUpdates on role==='audience'. The IO only makes sense for scroll-driven navigation in the audience layout; presenter navigation goes through keyboard/buttons via explicit navigate.next/previous. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>