design-system

Establish typography, an OKLCH color palette, and spacing as canonical design tokens. Typography drives the spacing scale; the palette is generated from the design briefing (or a supplied brand seed) into perceptually uniform OKLCH tint scales. Light mode only in v1 — dark mode is an open item for research-plan.md, never an invented palette.

generate-scale.mjs (in this skill directory, no dependencies) does the mechanics: typography <base> <ratio> · color <kind> <hue> <chroma> [lAdjust] · contrast <hex1> <hex2>.

Modes

Exactly one fires per invocation — declare which in your first output line.

• Pipeline — conducted by ateam-design. Never asks a question: every input derives from context.md's ## Design context per the derivation table below; what cannot derive becomes a visible TBD and a flag. Variant choice is the human's at the design gate; under a non-block gate_policy the skill self-selects the recommended variant only if the design bank's self-select consent was captured at the grill, recording it as a provisional call in research-plan.md.
• Standalone — a human invoked it directly. Run the upstream interactive flow exactly as written in Process below: ask, confirm, then write. Durable writes still require the read-back — standalone is not a back door.

Where tokens live (A-Team paths)

Source of truth, durable layer of the target repo — gate-reviewed, never silently overwritten (CONTRACT.md durable rules):

• docs/product/design-system/scale.ts — typography + spacing tokens
• docs/product/design-system/palette.ts — color tokens
• docs/product/design-system/shadcn-theme.css — the shadcn role-variable bridge (A-Team extension, below)

Materialised for the lofi (when docs/features/<slug>/lofi/ exists):

• docs/features/<slug>/lofi/src/styles/tokens.css — :root { --... } block
• docs/features/<slug>/lofi/tailwind.config.mjs — references var(--...)
• docs/features/<slug>/lofi/scale-variants/{name}.css and palette-variants/{name}.css — alternate token blocks for ?scale= / ?palette= comparison

If no lofi exists yet, write only the source-of-truth files; the lofi picks them up when build-lofi runs.

Production materialisation (the target's src/, Tailwind config, shadcn install) is never this skill's write — the dev phase materialises against spec.md's mapping. Whether the target uses Tailwind v3 config or v4 @theme is a dev-time fact read from the target repo; the CSS variables here are version-agnostic.

Create-once

Before generating anything, check for an existing system:

1. docs/product/design-system/ exists, or A-Team Config's design system path points at a real token source → consume, don't regenerate. Read the tokens as settled facts; report them; stop.
2. If ## Design context now contradicts the existing tokens (e.g. "avoid blue" while brand-500 is blue), do not auto-regenerate — surface the contradiction as a flag at the design gate and let the human decide.
3. Regeneration has exactly two triggers: an explicit human instruction (gate revision notes, or standalone invocation saying so). Never spontaneous.

Pipeline derivation — replaces the interview

The upstream questions are answered from durable context, not asked. Scan the target first (the design bank's own rule): existing tokens/CSS variables, brand assets, style guides — a fact the repo already answers is read, not derived.

Upstream input	A-Team source	When absent
Specimen category (sans/serif/mono/display)	## Design context typography answer (design-intake bank)	default sans-serif (upstream default); mark derived
Scale preset (base, ratio)	## Design context density/feel answer	derive from aesthetic direction — calm/airy/editorial → Relaxed · dense/fast/technical → Compact · spacious/luxury → Spacious · else Balanced; mark derived, emit 2–3 scale variants for the gate
Brand seed (hex/hue/brand name)	## Design context color constraints; brand assets found in the target	TBD-draft (below) + blocking flag
Domain/industry	context.md ## Overview	—
Mood axes	## Design context users & emotional goals + brand personality	derived from adjacent fields; flag
Reference / anti-reference brands	## Design context aesthetic direction	skip nudging toward references; note the gap
Audience sophistication	## Design context users	derived; flag
Colors to avoid	## Design context color constraints	—
WCAG bar	## Design context accessibility	default AA (4.5:1 body)

TBD-draft (no brand seed anywhere): the design lead's red flag — never pick colors from nothing — holds in substance: generate everything that needs no brand opinion (neutral scale at a default hue bias, the four fixed-hue semantics, the full typography pass), write brand/accent as explicit TBD: no brand seed in Design context, and report it as a blocking flag in the phase report. The lofi stays greyscale regardless, so nothing downstream is blocked from rendering — only from shipping a brand nobody chose.

Every derived value is listed in design.md's options/reasoning section and appended to research-plan.md's ## Assumptions tagged · [design phase] with a confidence level.

Process

The guideline content below is the design lead's, preserved from upstream. "Ask" steps fire in standalone mode; pipeline mode answers them from the derivation table.

Pass 1: Typography

1. Specimen category. Ask: sans-serif (default), serif, monospace, or display? Don't ask for a specific font yet — the fontFamily block gets a TODO: project font placeholder; system fallback stack is filled per category.

2. Pick presets. Show the four curated presets plus an optional custom tuple:

   Preset	Base	Ratio	Character
   Compact	16	1.2	fast, dense
   Balanced	16	1.333	steady
   Relaxed	18	1.414	calm
   Spacious	20	1.5	airy
   Custom	user-supplied (base, ratio)	—

   Ask the user to pick one preset, or "show me a few to compare." Multiple → emit as variants under scale-variants/.

3. Compute the scale. Invoke node generate-scale.mjs typography <base> <ratio>. The script returns:

   • sizes: { caption, body, h3, h2, h1 } — each snapped to a multiple of 4, with anti-collision applied.
   • lineHeights: matching, each a multiple of 8 (baseline grid is half, so a multiple of 4).
   • spacing: { xs:4, s:8, m:16, l:24, xl:32, xxl:48 } — fixed for v1.
   • warnings: any string describing collisions that required ≥2 bumps.

4. Surface warnings. If warnings is non-empty, print the message verbatim. Soft warning only — do not block, do not auto-pick another preset. Let the user decide (pipeline: keep the preset, carry the warning into the gate report).

Pass 2: Color

1. Brand seed check. Ask: "Do you already have brand colour(s) you need to lock — hex, hue, or a brand name?" If yes → skip the vibe interview; convert the supplied input into a seed hue/chroma pair and continue.

2. Vibe interview (only if no seed; pipeline reads these from ## Design context). Five questions, in order:

   1. What domain or industry is the product in?
   2. Mood on three axes: warm↔cool, calm↔energetic, sophisticated↔playful.
   3. Reference brand to lean toward + one to feel distinct from.
   4. Audience sophistication.
   5. Anything to actively avoid.

3. Propose seed hues (reasoning from the interview). Surface these before generating (pipeline: in design.md's reasoning, reviewed at the gate).

   • Brand hue (H 0–360°), chroma 0.10–0.20 (low for sophisticated/calm, high for energetic/playful).
   • Neutral hue, chroma 0.01–0.03, biased ±15° from brand for tonal harmony.
   • Optional accent hue (90° or 180° from brand) if the vibe needs a counter-colour.
   • Semantic placeholders: success 145°, warning 70°, error 25°, info 240°. These are fixed per-language convention; only the lightness curve adapts.

4. Generate tint scales. Invoke node generate-scale.mjs color <kind> <hue> <chroma> for each scale (brand, neutral, accent if any, four semantics). The script returns 10 steps (50, 100, …, 900) as { oklch, hex } pairs.

5. WCAG nudge loop (max 2 iterations).

   • Check contrast: brand-500 on neutral-50, and neutral-50 on brand-500.
   • If either is below 4.5:1, regenerate with the L curve adjusted down 0.02 at the relevant steps (lAdjust).
   • After 2 nudges, if still failing, surface the failure. Don't ship a low-contrast palette silently.

6. Generate variants if requested. "Show me 3 palettes" (pipeline: the diverge-by-default requirement) → generate two or three with slightly varied hue/chroma seeds, write to palette-variants/, and record in design.md why each exists and which is recommended.

Anti-collision rule (typography)

Body is the anchor. Snap each scale level to nearest multiple of 4. Walk levels above body upward: each must be ≥ previous + 4 (bump if not). Walk levels below body downward: each must be ≤ previous − 4 (bump if not).

If any level required ≥2 bumps, surface a soft warning: "Ratio X at base Y collides too tight. Try a wider ratio or larger base." Continue writing — do not hard-stop. The user picks.

Token format

docs/product/design-system/scale.ts

export const scale = {
  fontFamily: {
    // TODO: project font
    sans: 'ui-sans-serif, system-ui, -apple-system, sans-serif',
  },
  base: 16,
  ratio: 1.333,
  sizes: { caption: 12, body: 16, h3: 20, h2: 24, h1: 32 },
  lineHeights: { caption: 16, body: 24, h3: 28, h2: 32, h1: 40 },
  spacing: { xs: 4, s: 8, m: 16, l: 24, xl: 32, xxl: 48 },
} as const;

docs/product/design-system/palette.ts

export const palette = {
  brand: {
    50: { oklch: 'oklch(0.985 0.02 240)', hex: '#f6faff' },
    // ... 100–900
  },
  neutral: { /* same shape */ },
  semantic: {
    success: { default: { oklch: '...', hex: '...' }, bg: { oklch: '...', hex: '...' } },
    warning: { /* ... */ },
    error:   { /* ... */ },
    info:    { /* ... */ },
  },
} as const;

docs/features/<slug>/lofi/src/styles/tokens.css

:root {
  /* Typography */
  --font-sans: ui-sans-serif, system-ui, -apple-system, sans-serif;
  --size-body: 16px;
  --line-body: 24px;
  /* ...other sizes/line-heights/spacing */

  /* Brand scale (OKLCH triplets — space-separated, no commas) */
  --brand-50: 0.985 0.02 240;
  --brand-100: 0.965 0.04 240;
  /* ...200–900 */

  /* Neutral, semantic — same pattern */
}

docs/features/<slug>/lofi/tailwind.config.mjs

import { scale } from '../../../product/design-system/scale.ts';

export default {
  content: ['./src/**/*.{astro,html,js,ts}'],
  theme: {
    extend: {
      fontFamily: { sans: 'var(--font-sans)' },
      fontSize: {
        caption: ['var(--size-caption)', { lineHeight: 'var(--line-caption)' }],
        body:    ['var(--size-body)',    { lineHeight: 'var(--line-body)' }],
        h3:      ['var(--size-h3)',      { lineHeight: 'var(--line-h3)' }],
        h2:      ['var(--size-h2)',      { lineHeight: 'var(--line-h2)' }],
        h1:      ['var(--size-h1)',      { lineHeight: 'var(--line-h1)' }],
      },
      spacing: scale.spacing,
      colors: {
        brand: {
          50:  'oklch(var(--brand-50))',
          100: 'oklch(var(--brand-100))',
          // ...
        },
        neutral: { /* ... */ },
        success: 'oklch(var(--success))',
        warning: 'oklch(var(--warning))',
        error:   'oklch(var(--error))',
        info:    'oklch(var(--info))',
      },
    },
  },
};

lofi-lint.mjs treats the fontSize keys above as type roles and accepts color keys only when their effective configured leaf value is bound through a CSS custom property (for example, oklch(var(--brand-500))). It merges theme.colors with theme.extend.colors before granting names, so a literal override removes an earlier token binding. Fallbacks must also be token-only: var(--surface, var(--fallback)) is valid, while var(--surface, red) is not. Keep target-specific nested role names intact: a surface.raised binding authorizes bg-surface-raised, while a literal value such as red authorizes nothing. This lets canonical text-h1/text-body/text-caption and semantic utilities pass without allowing raw Tailwind palette or CSS named colors.

shadcn bridge — A-Team extension

Not upstream content. This section exists because shadcn/ui is the A-Team's declared-default component library (design-intake ## Declared defaults); shadcn themes through semantic role variables, and someone has to bind roles to scale steps exactly once. The binding is contrast-driven mechanics — every aesthetic opinion already lives in the scales above.

Write docs/product/design-system/shadcn-theme.css: a :root block binding shadcn's role variables to OKLCH scale steps. Default mapping (light mode):

Role var	Scale step	Role var	Scale step
--background	neutral-50	--muted	neutral-100
--foreground	neutral-900	--muted-foreground	neutral-600
--card / --popover	neutral-50	--accent	accent-100, else neutral-100
--card-foreground / --popover-foreground	neutral-900	--accent-foreground	accent-900, else neutral-900
--primary	brand-600	--destructive	error default
--primary-foreground	neutral-50	--destructive-foreground	neutral-50
--secondary	neutral-100	--border / --input	neutral-200
--secondary-foreground	neutral-900	--ring	brand-500

Rules:

• Every foreground/background pair must pass the WCAG bar (default AA 4.5:1) via generate-scale.mjs contrast. A failing pair walks its scale step darker/lighter one step at a time, max 2 steps — the same nudge discipline as the palette. Still failing → surface it, don't ship it.
• --radius has no source in the subvisual tokens: write --radius: 0.5rem; /* TBD: no radius opinion in the design system */ and record the open item in research-plan.md.
• Light mode only: no .dark block. Dark mode is an open item in research-plan.md, not an invented palette.
• File header comments record the mapping table and the contrast results, so the gate reviews the binding, not just the values.

Common mistakes

• Hard-coding hex without OKLCH source. Always store OKLCH primary, hex fallback. Editing hex by hand drifts the scale.
• Forgetting the WCAG nudge. Generated palettes can fail AA on key pairings. Run the check — on the palette and on the shadcn bridge pairs.
• Letting the user pick "any font". Push for the specimen category. Even "system sans-serif" is more useful than "TBD".
• Generating both passes silently. Standalone is interactive: ask, confirm, then write. Pipeline is derived: every non-obvious call lands in design.md's reasoning and the assumptions ledger — derived is not silent.
• Skipping the brand-seed branch. Most real projects have at least a brand color already. Always check ## Design context and the target's assets before deriving anything.
• Regenerating instead of consuming. An existing system is a settled fact. Re-running the generator over it is a silent overwrite of a durable artifact.

Red flags — STOP

• Standalone: user says "skip the vibe interview, just pick colors" without supplying a seed. Decline; ask for at least domain + mood.
• Pipeline: ## Design context has no brand/aesthetic data. Do the TBD-draft; never invent a seed to keep the run tidy.
• Generated palette fails WCAG after 2 nudges. Surface the failure; don't ship low-contrast tokens.
• Custom typography tuple produces ≥2 collision bumps on any level. Warn explicitly; offer (standalone) or fall back to (pipeline, flagged) a curated preset.
• Existing docs/product/design-system/ and no explicit regeneration instruction. Consume it; report; stop.