Specification

The authoritative spec lives in SPEC.md at the repository root and is the source of truth for both implementations.

It covers:

§1 — Accepted inputs (Python vs JS)
§2 — The eight-stage pipeline (fetch → rasterize → mask → pad → trace → outer-shell → simplify → emit)
§3 — Output formats and exact serialisation rules
§4 — Python-only “smart” features (colour-distance bg detection, auto-contrast, adaptive thresholding, batch)
§5 — The JavaScript subset (what’s deliberately not there)
§6 — Defaults table
§7 — CLI surface
§8 — Error model
§9 — Determinism and reproducibility rules
§10 — Cross-language parity contract: byte-identical JSON / CSS on the shared surface
§11 — Performance targets
§12 — Target repository layout
§13 — Versioning (single git tag releases both packages)

If the spec and an implementation disagree, the spec wins. PRs should update the spec before changing behaviour.