BrandHueRequired [constraint] v1.0.0

Brand color systems must derive their primary ramp from a single OKLCH hue (one --hue variable feeding 9–12 lightness stops at calibrated chroma). Multi-hue ad-hoc palettes assembled from picked hex values are forbidden for new design systems.

Target

• brand color system
• primary palette ramp
• design-token color scaffolding

Severity

high

Values

• • Required: single --hue: CSS custom property feeding all primary ramp stops
• • Required: ramp generated by holding chroma constant or following a documented chroma curve while varying L
• • Forbidden: ad-hoc hex picks per ramp stop with no shared hue anchor

Exceptions

• Multi-brand products where each tenant supplies a hue (each tenant ramp must still be single-hue).
• Categorical chart palettes (qualitative encoding requires multiple hues — see @community/category-data-viz).
• Legacy products mid-migration (hex-based) — flagged but not blocked.

Approved Alternatives

• @impeccable/template-oklch-palette — 12-stop scaffold parameterised by --hue
• Radix Colors (12-step OKLCH-derived ramps per hue)
• Tailwind v4 OKLCH palette (per-hue, perceptually balanced)

Enforcement

Design-token review: every primary ramp token must reference --hue (or a hue-derived token); CI lint rejects literal H values inside oklch() calls in primary ramps unless they equal var(--hue).

BrandHueRequired [constraint] v1.0.0

Brand color systems must derive their primary ramp from a single OKLCH hue (one --hue variable feeding 9–12 lightness stops at calibrated chroma). Multi-hue ad-hoc palettes assembled from picked hex values are forbidden for new design systems.

Target

• brand color system
• primary palette ramp
• design-token color scaffolding

Severity

high

Values

• • Required: single --hue: CSS custom property feeding all primary ramp stops
• • Required: ramp generated by holding chroma constant or following a documented chroma curve while varying L
• • Forbidden: ad-hoc hex picks per ramp stop with no shared hue anchor

Exceptions

• Multi-brand products where each tenant supplies a hue (each tenant ramp must still be single-hue).
• Categorical chart palettes (qualitative encoding requires multiple hues — see @community/category-data-viz).
• Legacy products mid-migration (hex-based) — flagged but not blocked.

Approved Alternatives

• @impeccable/template-oklch-palette — 12-stop scaffold parameterised by --hue
• Radix Colors (12-step OKLCH-derived ramps per hue)
• Tailwind v4 OKLCH palette (per-hue, perceptually balanced)

Enforcement

Design-token review: every primary ramp token must reference --hue (or a hue-derived token); CI lint rejects literal H values inside oklch() calls in primary ramps unless they equal var(--hue).

Rationale

OKLCH-derived single-hue ramps produce perceptually uniform lightness progressions and trivially mirrorable dark-mode tokens. Ad-hoc hex ramps drift in hue across stops (the 100 stop reads warm, the 700 stop reads cool), break dark-mode parity, and require manual contrast tuning at every stop. The constraint also enforces brand discipline — one hue is the brand.