- engine: QuickJob — what to show the moment a photo opens: the loupe's last render for the
current settings (kept by Session::loupe_job under a size-independent "view" key in the
preview cache, memory + disk with a library; the disk JPEG is written off the render
thread via PreviewCache::put_deferred), else the embedded camera JPEG of a raw that still
has its import look (import::has_import_look), else a thumbnail-level render.
- Grid / filmstrip: an unedited raw without a thumbnail shows its cached thumbnail, else its
embedded preview (Slot::ThumbQuick) at once; the real rendered thumbnail follows at
background priority (same cache keys, so it still ends up matching the develop render;
edited photos render directly).
- Loupe (detail, compare, filmstrip selection): Slot::Preview holds the stand-in until
Slot::Main has the photo; the full render then replaces it in place (no blank frame).
- files::embedded_preview_srgb + PreviewLoader hook (desktop/CLI/MCP and web).
- ui.inspect → loupe {photo, source: render|cached|embedded|small|thumb|none, pending}.
Real app (24 MP raws, loaded machine): first image 15–90 ms (thumbnail, then embedded
preview), full render 0.2–0.5 s (was 1.0–2.4 s with nothing shown before it).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Renders run in dedicated module Web Workers, each a second instance of the app's wasm module
(index.html compiles it once and posts the WebAssembly.Module to worker.js). A job crosses as
JSON (WireJob: source, settings, request); the worker reads originals and cached thumbnails from
browser storage itself, keeps decoded sources and per-view stage caches, and transfers RGBA back.
Jobs follow the worker that decoded the photo; the loupe waits for it. No wasm threads or
SharedArrayBuffer needed; falls back to inline rendering if no worker starts (?workers=0).
Thumbnail disk cache on the web: thumbs/<key>.jpg in OPFS/IndexedDB with an index on the main
thread, pruned to the desktop budget (2 GB → 80 %, LRU).
ui-egui: RenderOffload hook in the Renderer (queue/priorities/dedup stay in the UI).
engine: RenderJob.origin + MediaCache::origin_ref; preview: encode_jpeg/decode_jpeg public.
xtask web: copies worker.js; --serve sends COOP/COEP/CORP (documented in docs/web.md).
Headless Chrome, cold load + grid scroll, 24 demo photos: main-thread busy 12.4 s → 0.7–1.1 s,
long tasks 23 (max 1.1 s) → 0; grid filled in 6.3–8.4 s vs 13–16 s; slider job 4 ms.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- new crate lightcraft-preview (L3): 128-bit content hashing (SipHash-1-3),
cost-bounded Lru, DiskCache (JPEG q90 files keyed by content hash +
settings hash + size + RENDER_CACHE_VERSION; temp+rename writes; LRU prune
by mtime to 80% of budget; corrupt files dropped), PreviewCache (memory
LRU over disk), JobPool (per-slot dedupe, priorities, reprioritize/drop,
inline mode for wasm).
- engine: Session::thumb_job buckets thumbnails to 128/256/384/512 and serves
them from the cache without decoding the source; decoded thumbnail
sources now in a 384 MB LRU (was unbounded); library attaches
<library>/thumbs; library.info cache stats; library.clearPreviews.
- ui-egui: Renderer runs on JobPool; thumbnails scrolled out of the
prefetch area are dropped from the queue; on-screen thumbnails get
re-prioritized; ui.inspect reports in-flight renders + thumb textures.
- Demo library (24 photos): grid fully drawn 4.4 s cold -> 0.21 s warm
(24/24 disk hits, no source decoded).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Brandon Thomas