An RGBA_F32 image with an sRGB tag comes back off the GPU backend sampled on a 1/255 grid; the same shader on a raster surface returns the floats untouched. The plane is raw/65535, so the shadows the black level is there to keep sit at 1e-3 and quantise to zero -- a 3010x2012 develop landed 41189 pixels under luma 2 with the dark end speckled blue/yellow, against none on the raster surface. A half is uploaded as float, so the plane stays exact either way. Rejects the earlier guess that the render target's colour space was to blame: gpu+rt-srgb and gpu+img-untagged came back byte-identical to gpu. scripts/half-check.mjs checks the conversion: the named encodings, and no plane value in a 14-bit sensor's range moving more than 4.8e-4 relative.
RecipesCam web — self-contained stack
A Docker-hosted web build of RecipesCam. Everything it needs is in this folder: move it to another machine, run two commands, and the app is up. It does not need the React Native project around it.
cp .env.example .env
docker compose up -d --build
# → http://localhost:8090
What runs where
| Service | Image | Role |
|---|---|---|
frontend |
nginx:1.27-alpine (built by frontend/Dockerfile) |
Static SPA + /api/ reverse proxy |
api |
node:22-slim (built by backend/Dockerfile) |
Accounts + saved recipes, SQLite on ./data |
frontend resolves api through Docker's embedded DNS and proxies /api/* to
it — that is why the API container is named api and why it is not published on
the host. Only ${WEB_PORT:-8090} is exposed.
Photos never leave the browser. The CanvasKit render pipeline (grade, frame, watermarks, JPEG encode) runs in the visitor's tab; the API only stores recipes as JSON.
Layout
docker-compose.yml the stack
.env.example WEB_PORT
data/ SQLite (created on first run, gitignored)
backend/ Fastify + better-sqlite3 API, own Dockerfile
frontend/ Vite + React + CanvasKit SPA, own Dockerfile + nginx.conf
shared/ vendored copies of the app's types + utils (see below)
src/engine/ skiaShim.ts (CanvasKit) + exportEngine.ts (render pipeline)
+ session.ts (localStorage/IndexedDB studio persistence)
Vendored files
frontend/shared/{types/index.ts,utils/*.ts} are byte-identical copies of
src/types/index.ts and ten src/utils/*.ts files from the React Native
project (@shopify/react-native-skia is aliased to src/engine/skiaShim.ts in
vite.config.ts + tsconfig.json, so those files compile unchanged):
cinemaShader colorUtils defaultRecipes exifWrite frameUtils jpegDpi
paramDefs recipeShare skiaImage toneShader.
The landing page needs no CDN: frontend/public/assets/fonts/*.woff2 are the
seven self-hosted faces behind the three font groups the Themes menu offers
(Plus Jakarta Sans / Inter / JetBrains Mono, Fraunces / Be Vietnam Pro /
Courier Prime, Be Vietnam Pro / Space Mono — all SIL OFL, pulled from Google
Fonts, vietnamese + latin + latin-ext subsets), and
frontend/public/assets/samples/s*.jpg are the six placeholder negatives the
film strip, preset tester and QR card show (swap them for real graded stills
whenever we have them). Its one foreign request is the QR image from
api.qrserver.com, which degrades to an empty slot offline.
When the app changes one of them, copy it back in — the renderer is only "parity" for as long as these stay in sync:
cd <repo>/docker/frontend/shared/utils
cp <repo>/src/utils/<name>.ts .
Operations
docker compose logs -f api # API log
docker compose restart api # after backend/src changes (rebuild: --build)
docker compose down # stop; ./data survives
Backup is the ./data folder — that is the whole database.
Checks
curl -s http://localhost:8090/api/health # {"ok":true}
curl -sI http://localhost:8090/ # 200, index.html
Then open the UI, drop a photo in, and confirm the preview shows the picture and
EXPORT downloads a JPEG that opens. The preview going solid black while the
export still reports a plausible size is the one failure mode worth knowing: it
means the CanvasKit GPU surfaces lost their shared GrDirectContext (see
frontend/src/engine/skiaShim.ts), and with no GPU the raster fallback renders
the same pipeline correctly, just slower.