dt-design-system

name: dt-design-system description: >- Creates and modifies Digitaltableteur UI components, layout patterns, Storybook stories, contracts, and design tokens under nextjs-app/shared/. Use when the user says "new component", "scaffold component", "Storybook story", "design system", "CSS Modules", "component contract", "validate:components", or edits files in shared/components or shared/patterns. Do NOT use for Next.js page routes (use dt-nextjs-app) or API endpoints (use dt-api-routes). metadata: version: 1.1.0 category: design-system

Design system workflow

Instructions

Step 1: Load context

1. Read references/area-guide.md
2. Before creating UI, run dt-use-existing-component or npm run find-component -- "your intent".
3. Search for existing components before creating new ones:

rg -n "<SimilarName" nextjs-app/shared/components/

3. For new components, open docs/LLM_COMPONENT_GENERATION_RULES.md by relevant section only — do not paste the full 12k-word doc into context.

Step 2: Scaffold (new component)

npm run new-component ComponentName

Expected output: folder under nextjs-app/shared/components/ComponentName/ with .tsx, .module.css, .stories.tsx, .test.tsx, .contract.json, .spec.md, .mdx, index.ts.

CRITICAL before finishing:

• WIP badge on Storybook story until promoted
• axe-core assertion in .test.tsx
• EN / FI / SV keys if user-facing strings
• Design tokens from variables.css — no hardcoded colors

Step 3: Validate

npm run validate:components
npm test -- ComponentName

If validation fails, halt and fix reported contract/spec/MDX issues before proceeding.

Step 4: Promote (remove WIP badge)

Only when ALL pass:

• Unit + axe tests green
• npm run test:stories:smoke for the story
• Full i18n coverage
• Visual check in Storybook or via npx agent-browser

Ask the user before promoting contract status to stable.

Token changes

npm run build:tokens

Regenerates nextjs-app/shared/foundations/dist/agent-manifest.json.

@dt usage gate

Do not replace pattern-level <h*> / header chrome <button> with @dt/Title / @dt/Button unless explicitly requested — that changes typography and breaks section CSS. Fix heading levels only (h3 → h2) while keeping existing classes. npm run lint:dt-usage flags @/components/ui/* in app/, patterns, pages, and shared components (known shadcn debt allowlisted).

Agent / MCP discovery

• CLI: npm run find-component -- "your intent"
• Local MCP: npm run ds:mcp (stdio — see docs/DESIGN_SYSTEM_MCP.md)
• HTTP: /mcp on production (design-system tools + consulting)

Examples

Example 1: New Button variant

User says: "Add a ghost variant to Button"

Actions:

1. Load existing nextjs-app/shared/components/Button/
2. Update Button.tsx, Button.module.css, Button.contract.json, Button.spec.md
3. Add story variant + test coverage
4. Run npm run validate:components && npm test -- Button

Example 2: New layout pattern

User says: "Create a pricing table pattern"

Actions:

1. Check nextjs-app/shared/patterns/ for similar patterns
2. Compose from @dt primitives (Title, Text, Card, Grid) — no raw <h2> or <p>
3. Follow same contract/story/test structure as components
4. Run validation gates

Troubleshooting

validate:components fails on contract

Cause: props in .tsx drifted from .contract.json or spec has open TODOs at beta+.

Solution: align contract schema with exported props; rewrite stub MDX/spec prose flagged in agent-manifest.json.

Storybook story missing WIP badge

Cause: scaffolder default removed manually.

Solution: restore WIP badge until a11y + visual + i18n gates pass.

Tests fail on axe violations

Cause: missing labels, contrast, or keyboard support.

Solution: fix a11y in component first; do not suppress axe rules without documented justification in spec.

Boundaries

• MUST NOT use inline styles (except dynamic backgroundImage)
• MUST NOT create single-file components outside folder structure
• MUST NOT remove WIP badge without full verification gate