svelte-kit-vice/scripts/contrast-audit.ts

/**
 * Contrast audit — Stage 1 of the "tonal-ramp contrast parity" initiative
 * (docs/next-features.md §1). Measures whether the framework's slot-pair
 * contrast PROMISES actually hold across all 33 donor scales × 2 modes, and
 * prints the drift list for user verdicts (retune vs annotated exception).
 *
 * This is measurement only — it changes no output. The pair table below is the
 * proposed doctrine (grounded in the registry's stated promises); adjust it and
 * re-run. WCAG 2 is the normative gate (4.5:1 text · 3:1 non-text); APCA Lc is
 * reported alongside (the framework's on-solid criterion already uses APCA — the
 * verdict phase can promote it to a co-gate).
 *
 *   node --import tsx/esm scripts/contrast-audit.ts
 */
import { apcaLc, oklchToGammaRgb, safeParseColor, wcagContrastRatio } from '$color'
import { PALETTE_SCALES } from '../src/uix/eidos/lib/types.ts'
import {
	THEME_BASE_DARK_COLOR_SCALES,
	THEME_BASE_LIGHT_COLOR_SCALES
} from '../src/uix/eidos/lib/themes/base.ts'

type StepMap = Record<string | number, string | undefined>

interface Pair {
	/** Foreground step (the ink / border). */
	ink: number
	/** Background step. */
	bg: number
	label: string
	/** WCAG 2 floor (the normative gate). */
	wcag: number
	kind: 'text' | 'non-text'
}

// Proposed pair table — the promises the registry §1 names as "unmeasured".
// Radix functional steps: 1 track · 2 subtle-bg · 3 element-bg · 7 UI border ·
// 9 solid · 11 text · 12 text-strong.
const PAIRS: readonly Pair[] = [
	{ ink: 11, bg: 1, label: 'text·11 over track·1', wcag: 4.5, kind: 'text' },
	{ ink: 11, bg: 2, label: 'text·11 over bg·2', wcag: 4.5, kind: 'text' },
	{ ink: 11, bg: 3, label: 'text·11 over element·3', wcag: 4.5, kind: 'text' },
	{ ink: 12, bg: 1, label: 'textStrong·12 over track·1', wcag: 4.5, kind: 'text' },
	{ ink: 12, bg: 3, label: 'textStrong·12 over element·3', wcag: 4.5, kind: 'text' },
	{ ink: 7, bg: 1, label: 'border·7 over track·1', wcag: 3, kind: 'non-text' },
	{ ink: 7, bg: 2, label: 'border·7 over bg·2', wcag: 3, kind: 'non-text' }
]

function measure(inkHex: string, bgHex: string): { wcag: number; apca: number } | null {
	const ink = safeParseColor(inkHex)
	const bg = safeParseColor(bgHex)
	if (!ink || !bg) return null
	const inkRgb = oklchToGammaRgb(ink)
	const bgRgb = oklchToGammaRgb(bg)
	return { wcag: wcagContrastRatio(inkRgb, bgRgb), apca: Math.abs(apcaLc(inkRgb, bgRgb)) }
}

const MODES: readonly [string, Record<string, StepMap>][] = [
	['light', THEME_BASE_LIGHT_COLOR_SCALES as unknown as Record<string, StepMap>],
	['dark', THEME_BASE_DARK_COLOR_SCALES as unknown as Record<string, StepMap>]
]

interface Row {
	mode: string
	scale: string
	pair: string
	wcagFloor: number
	wcag: number
	apca: number
}

const failures: Row[] = []
let checked = 0

for (const [mode, scales] of MODES) {
	for (const scale of PALETTE_SCALES) {
		const steps = scales[scale]
		if (!steps) continue
		for (const p of PAIRS) {
			const inkHex = steps[p.ink]
			const bgHex = steps[p.bg]
			if (!inkHex || !bgHex) continue
			const c = measure(inkHex, bgHex)
			if (!c) continue
			checked++
			if (c.wcag < p.wcag) {
				failures.push({
					mode,
					scale,
					pair: p.label,
					wcagFloor: p.wcag,
					wcag: c.wcag,
					apca: c.apca
				})
			}
		}
	}
}

// ── Report ────────────────────────────────────────────────────────────────
const f2 = (n: number) => n.toFixed(2)
console.log(`\nContrast audit — ${checked} pair-checks (${PALETTE_SCALES.length} scales × 2 modes × ${PAIRS.length} pairs)\n`)

if (failures.length === 0) {
	console.log('✅ No WCAG drift — every measured pair clears its floor.\n')
} else {
	// Group by pair, then mode.
	const byPair = new Map<string, Row[]>()
	for (const r of failures) {
		const key = r.pair
		;(byPair.get(key) ?? byPair.set(key, []).get(key)!).push(r)
	}
	console.log(`⚠️  ${failures.length} pair-checks below the WCAG floor:\n`)
	for (const [pair, rows] of byPair) {
		console.log(`── ${pair}  (floor ${rows[0].wcagFloor}:1) — ${rows.length} fail`)
		for (const r of rows.sort((a, b) => a.wcag - b.wcag)) {
			console.log(
				`     ${r.mode.padEnd(5)} ${r.scale.padEnd(10)} WCAG ${f2(r.wcag)}:1   APCA Lc ${f2(r.apca)}`
			)
		}
		console.log('')
	}
}

// Summary by pair (fail count) — the shape of the drift.
console.log('Summary (fails per pair):')
for (const p of PAIRS) {
	const n = failures.filter((r) => r.pair === p.label).length
	console.log(`  ${n === 0 ? '✅' : '⚠️ '} ${p.label.padEnd(30)} ${n}/66`)
}
console.log('')