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
				})
			}
		}
	}
}

// ── Tier-1: the LOAD-BEARING borders (WCAG 1.4.11 — 3:1 required) ───────────
// The per-scale `border` (step 7) is a DECORATIVE accent (used only when a
// filled/colored element also carries its boundary via bg + content) → exempt.
// The borders that ARE the sole indicator of a control's boundary/state use
// STRONGER tokens; those are the real 3:1 promise. Role bindings in the base:
// neutral→gray, primary→purple, risk→orange.
function compositeSrgb(fgHex: string, alpha: number, bgHex: string): string | null {
	const fg = safeParseColor(fgHex)
	const bg = safeParseColor(bgHex)
	if (!fg || !bg) return null
	// `oklchToGammaRgb` returns a normalized [0,1] `[r,g,b]` tuple — scale to [0,255].
	const f = oklchToGammaRgb(fg)
	const b = oklchToGammaRgb(bg)
	const hex = (i: 0 | 1 | 2) =>
		Math.max(0, Math.min(255, Math.round((f[i] * alpha + b[i] * (1 - alpha)) * 255)))
			.toString(16)
			.padStart(2, '0')
	return `#${hex(0)}${hex(1)}${hex(2)}`
}

// Role bindings in the base theme: neutral→gray, primary→purple, risk→orange.
const NEUTRAL = 'gray'
const PRIMARY = 'purple'
const RISK = 'orange'
const FOCUS_ALPHA: Record<string, number> = { light: 0.48, dark: 0.52 }
const RING_ERROR_ALPHA: Record<string, number> = { light: 0.52, dark: 0.56 }

// The surfaces a control (and thus its border) sits on.
const SURFACES: readonly { id: string; step: number }[] = [
	{ id: 'default', step: 1 },
	{ id: 'raised', step: 2 },
	{ id: 'muted', step: 3 }
]

interface BorderToken {
	label: string
	/** `true` = the sole indicator of a boundary/state → WCAG 1.4.11 wants 3:1. */
	loadBearing: boolean
	/** Resolve the (already-composited) border color for a mode's scale map. */
	color: (s: Record<string, StepMap>, mode: string, surfaceHex: string) => string | undefined
}
const BORDER_TOKENS: readonly BorderToken[] = [
	{ label: 'border-subtle (neutral·4)', loadBearing: false, color: (s) => s[NEUTRAL]?.[4] },
	{ label: 'border-default (neutral·6) — resting', loadBearing: false, color: (s) => s[NEUTRAL]?.[6] },
	{ label: 'border-strong (neutral·8) — hover/ghost', loadBearing: true, color: (s) => s[NEUTRAL]?.[8] },
	{
		label: 'focus ring (primary·8 @ ~50%)',
		loadBearing: true,
		color: (s, mode, surf) => {
			const fg = s[PRIMARY]?.[8]
			return fg ? (compositeSrgb(fg, FOCUS_ALPHA[mode], surf) ?? undefined) : undefined
		}
	},
	{
		label: 'focus ring-error (risk·8 @ ~54%)',
		loadBearing: true,
		color: (s, mode, surf) => {
			const fg = s[RISK]?.[8]
			return fg ? (compositeSrgb(fg, RING_ERROR_ALPHA[mode], surf) ?? undefined) : undefined
		}
	},
	{ label: 'invalid border (risk·7)', loadBearing: true, color: (s) => s[RISK]?.[7] },
	{ label: 'checked/selected (primary·9 solid)', loadBearing: true, color: (s) => s[PRIMARY]?.[9] }
]

interface T1Row {
	mode: string
	surface: string
	label: string
	loadBearing: boolean
	wcag: number
	apca: number
	pass: boolean
}
const t1: T1Row[] = []
for (const [mode, scales] of MODES) {
	for (const surf of SURFACES) {
		const surfaceHex = scales[NEUTRAL]?.[surf.step]
		if (!surfaceHex) continue
		for (const bt of BORDER_TOKENS) {
			const c = bt.color(scales, mode, surfaceHex)
			if (!c) continue
			const m = measure(c, surfaceHex)
			if (!m) continue
			t1.push({
				mode,
				surface: surf.id,
				label: bt.label,
				loadBearing: bt.loadBearing,
				wcag: m.wcag,
				apca: m.apca,
				pass: m.wcag >= 3
			})
		}
	}
}

// ── 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 (per-scale pairs — fails/66):')
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  ${p.kind === 'non-text' ? '(non-text · see Tier-1 below)' : ''}`)
}
console.log('')

// ── Semantic border matrix (the tokens that ARE used as borders) ────────────
// `L` = load-bearing (sole indicator → WCAG 1.4.11 wants 3:1); `·` = decorative
// (accompanied by a fill / other cue → exempt). Floor 3:1 for the L rows.
console.log('Semantic border matrix — WCAG:1 vs each surface (L = load-bearing/3:1-required):\n')
const surfIds = SURFACES.map((s) => s.id)
const header = `  ${'token'.padEnd(38)} ${'kind'.padEnd(4)} ` + surfIds.map((s) => `${('' + s).padEnd(14)}`).join('')
for (const mode of ['light', 'dark']) {
	console.log(`── ${mode} (surface: default·1 / raised·2 / muted·3)`)
	console.log(header)
	for (const bt of BORDER_TOKENS) {
		const cells = surfIds.map((sid) => {
			const r = t1.find((x) => x.mode === mode && x.surface === sid && x.label === bt.label)
			if (!r) return ''.padEnd(14)
			const mark = !r.loadBearing ? ' ' : r.pass ? '✅' : '⚠️'
			return `${mark}${f2(r.wcag)}`.padEnd(14)
		})
		console.log(`  ${bt.label.padEnd(38)} ${(bt.loadBearing ? 'L' : '·').padEnd(4)} ${cells.join('')}`)
	}
	console.log('')
}
const lbFails = t1.filter((r) => r.loadBearing && !r.pass)
console.log(
	lbFails.length === 0
		? 'Load-bearing borders: ✅ all clear 3:1.\n'
		: `Load-bearing 3:1 FAILURES: ${lbFails.length}  →  ${[...new Set(lbFails.map((r) => r.label))].join(' · ')}\n`
)