Original LayerEditor related image compositing exercise

The assets are authored geometric raster layers and not a model output
Use Bun 1.3.11 sharp 0.34.5 Biome 2.2.2 and Python standard library
Copy layereditor-study.ts build-layereditor-assets.ts build-layereditor-pack.py verify-layereditor-pixels.py layereditor-source-audit.json and this file to a fresh directory
bun add sharp@0.34.5
bun add --dev @biomejs/biome@2.2.2
bun build-layereditor-assets.ts .
python3 verify-layereditor-pixels.py .

The helper authors a 512 by 384 poster at two by two subpixel coverage
Layers store straight RGBA bytes with final per-layer byte rounding
The compositor uses source over in byte space over opaque white
Intermediate composition stays floating point and rounds once at the final output
It is not a linear light or color managed pipeline and does not implement the paper model
The correct order is background product seal
The wrong order is product seal background
The masked example appends the opaque flattened target to that wrong stack
The Python verifier independently decodes PNG chunks and filters checks CRCs recomputes every output pixel and compares saved numeric reports
The deterministic ZIP includes the three input PNGs separate target order JSON and readme
Browser uploads use browser decoded RGBA values and can differ from original encoded samples after color or alpha conversion
No model weights inference runtime extraction or recovery of hidden content was tested