The content fade mask on .scrollbody lives in the scrolling element's local
box, so its cut stop (--flow-cut) must ride scroll to stay at a fixed screen
line. Driving that from heroScroll's rAF lagged the native compositor scroll
by a frame on fast flicks, so the cut slid up and rows briefly showed above
where they should clip (user-reported).
Move --flow-cut to a CSS scroll-driven animation (@property + @keyframes +
animation-timeline: scroll(nearest block), @supports-gated), so it's a pure
function of scroll position evaluated on the compositor and can't lag. The
keyframe delta and animation-range share one oversized constant (100000px)
so the value is base + scrollTop for ANY scroll distance — necessary because
the artist page changes its own content height as it scrolls, making the
total range non-constant. apply() keeps the per-frame path only as the
unsupported-engine fallback.
Verified live: screen cut constant at 217px across scrollTop 300..2500,
--flow-cut == base+scrollTop exactly.
Working:
- PreviewOverlay.svelte mounted at app root; opens over a fixture manifest
(window.__previewFixture(n) in dev), inert background, player bar hidden,
focus trap, keyboard nav, F3 rail, T3 swaps, R1b capsule, accent extraction.
- previewSession.svelte.js: store + service wiring (production + fixture).
- Root integration in App.svelte; revision-gateway bumps + notePlaybackGeneration
threaded through state.svelte.js player entry points; api.win guarded so plain
vite browser mounts.
- Launcher on the artist page builds a real artist manifest and opens the modal
with a play-full starter.
- 70 JS tests still green.
Two bugs found and fixed during bring-up:
- effect_update_depth_exceeded: bleed-crossfade and bump effects read AND wrote
the same $state; wrapped writes in untrack(). This loop was breaking Svelte's
scheduler globally (even ui.* stopped reacting).
- accentFromImage now sets crossOrigin for remote covers.
KNOWN BROKEN (handoff): reel vertical centering. The active card stays centred
at index 0 but drifts by one stride per step. Root cause isolated — see
TODO-Feature-Docs/scrollable-track-previews/HANDOFF-PHASE2C.md.
The previous .git directory was found gutted (only info/ remained), so
history is unrecoverable locally. This commit restores version control
with the tree exactly as it stands: the working app, the preview-tracks
launcher on the artist hero, the scrollable-track-previews design bundle
(docs + approved mockups), and the Phase 0 validation artifacts.
KeelrLeek