Lumen 0.3.1

Performance

• Thumbnails no longer stat the source file per load — one less NAS roundtrip per photo while scrolling.
• Scroll-ahead thumbnail prefetch now tracks the actual viewport (NSCollectionView prefetching) instead of decoding the whole list up front.
• Two-tier thumbnail cache: small grid cells use a 256px tier, so the memory cache holds ~4x more thumbnails on dense grids.
• Month-grouped timeline no longer re-groups the whole library on every redraw.
• Large albums now sort off the main thread like other scopes.
• Background cache warming starts with the folder you're viewing.

Fixes & improvements

• Folders with subfolders in the sidebar can now be selected with a single click (previously double-click only).
• Finder-style arrow navigation in the grid: ←/→ move linearly and wrap across rows.