PageAsDeckWrapper

Behaviors delivered

Scroll-snap — scroll-snap-type: y mandatory on the inner container; direct-child <section> children get scroll-snap-align: start
Keyboard — Arrow ↑/↓, PageUp/Down, Home, End, c chrome toggle, f fullscreen
Double-click — upper half of viewport → prev; lower half → next
Section counter — floating top-right “NN / total”; updates via IntersectionObserver on scroll
Hash nav — #s-N on load jumps to section index N
Reveal-on-intersect — child .reveal-item elements fade-in when 15% intersecting

Event protocol

Dispatches deck:section-changed with {index, total, isFirst, isLast} on every section change (scroll-driven or programmatic). DeckChrome listens for this to update its prev/next button enabled state.
Listens for deck:section-prev / deck:section-next — so DeckChrome’s prev/next buttons fire the same nav code path as the keyboard.

This is the load-bearing seam that lets the chrome composite cleanly: navigation is single-source-of-truth even though click handlers and key handlers live in different components.

Section discovery

Counts only direct top-level <section> children of .ddd-deck-content — decorative nested <section> elements inside slot content are deliberately excluded from the count (would over-count “17 / 24” when only 17 slots).

CSS prefix discipline

Classes use .ddd-* prefix (e.g. .ddd-deck-wrapper, .ddd-deck-content, .ddd-section-indicator, .ddd-nav-hint). Chroma’s old class names (.deck-wrapper, .section-indicator) — chroma now consumes via shim, so any chroma global CSS targeting old names is broken; re-target or use the --ddd-scroll-* tokens.

Status

✅ Shipped — humain consumes via ScrollDeckPage; chroma consumes via local shim at chroma-decks/src/layouts/PageAsDeckWrapper.astro that re-exports the shell version

[[ScrollDeckPage]] — bundles PageAsDeckWrapper as the canonical scroll-deck overlay
[[DeckChrome]] — the floating chrome that uses the event protocol
[[DeckOverlay—Scroll-UI]] — the overlay layer that sits on top of PageAsDeckWrapper
[[../../plans/Lift-Chroma-Decks-Generic-Code-into-Shared-Shell]]