# Colour Plugin Ecosystem

## Background

`@suaveplan/colours` (v0.1.0) shipped with core RGB/HSL/HSV/LAB/LCH/OKLAB/OKLCH/XYZ/CMYK support, parsing, mixing, blending, and palette generation. An audit of the `../chromatism/` third-party library revealed several colour-science features that are valuable for design-tool, accessibility, and print-media use cases but were out of scope for the core universal-tier package.

## Scope

This change introduces four plugin packages that extend the colour system:

1. `@suaveplan/colour-convert-hsluv` — Perceptually uniform HSL variant with gamut mapping via HSLuv.org reference algorithm.
2. `@suaveplan/colour-convert-cieluv` — CIELUV, xyY, LMS cone response, and Bradford chromatic adaptation with CIE standard illuminants.
3. `@suaveplan/colour-filter-cmc` — CMC l:c Delta-E colour difference metric (configurable luminance and chroma weights).
4. `@suaveplan/colour-filter-cct` — Correlated Colour Temperature (CCT) in Kelvin via McCamy's formula, plus CCT-to-RGB approximation.

## Out of Scope

- ICC profile parsing / embedding (requires WASM or native bindings)
- CVD / colour-blind simulation (Brettel/Viénot models — future change)
- 1D/3D LUT loading and application (future change)

## Acceptance Criteria

- Each plugin package follows the genesis scaffold: `package.json`, `tsconfig.lib.json`, `vitest.config.ts`, `vite.config.ts`, `README.md`.
- Folder-per-file structure with explicit barrel exports.
- 100% Istanbul coverage on all `src/**/*.ts`.
- Sibling `.md` docs for every implementation file (≥200 words, required headings).
- `dep-graph.test.ts` and `tree-shake.test.ts` in every package.
- `sideEffects: false` in every `package.json`.
- All error codes use `defineCodes` from `@suaveplan/error`.
- All packages pass `bunx turbo lint typecheck test build test:coverage`.