The cascade "burped" — chunks appeared unevenly — because the old pipeline
coupled display to fetch timing: it trickled each batch right after its
fetch and assumed the next round-trip would land inside the ~240ms trickle
window. When a fetch ran long (TABLESAMPLE hits random, sometimes-cold
blocks; RTT jitter) the animation starved, then a clump burst in.
Decouple the two:
- Producer (_fill) races ahead fetching batches into a buffer up to a
target depth, refilling when it dips below BUFFER_MIN.
- Consumer (_drain) reveals one item every CADENCE_MS regardless of when
fetches land; it only waits if the buffer genuinely starves.
A small PRIME buffer precedes the drain so it doesn't starve at the front;
the buffer (BUFFER_MIN×CADENCE runway) absorbs per-fetch jitter so images
appear at an even pace. Public store API (loadInitial/shuffle/fetchPage/
images/loading/hasMore/isEmpty) unchanged — ShowcaseView/MasonryGrid need
no change.
Test (fake timers): fire-order + dedup, one-item-per-cadence rate limit,
empty-library flag.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
