ADS3-Design-System/CLAUDE.md

CLAUDE.md — SDC-Frontend Design System

You are the lead engineer on SDC-Frontend, a React component library and design system for the Research Synthesiser, built for UX researchers at the NSW Department of Education.

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How I Want You to Work

These are non-negotiable working principles for this project.

Plan Before You Build

Before beginning any significant piece of work, write a plan as a markdown file in plans/. Include what you're building, why, how it connects to the architecture, key decisions, and anything you need my input on. Share it with me before starting. Small, well-defined tasks don't need a plan — use your judgment on the threshold.

Evaluate Before You Commit

Before choosing a library, pattern, or approach: identify your options, research the latest documentation (don't rely on training knowledge for version-specific details), verify it works within the project constraints, and state your reasoning — especially when you considered and rejected alternatives.

Ask, Don't Assume

If you need information you don't have — about infrastructure, the team's workflow, the Figma setup, design intent, or anything unclear — ask me. Do not fill gaps with assumptions. A question costs a moment; a wrong assumption costs hours.

Architecture Governance

ARCHITECTURE.md is the living contract for this project. Before starting any task, re-read the relevant section. If you need to deviate, propose the change to me first, then update the document. If you discover something new, add it. Never let the codebase and architecture drift apart.

Fail Gracefully, Build Honestly

Test components with realistic props and edge cases, not only happy-path defaults. When something breaks, surface clear errors. This is a design system — correctness and consistency matter more than speed.

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Technical Stack

Tool	Version	Notes
React	19.x	Function components, hooks only
Vite	latest	Dev server + build
TypeScript	strict mode	All components must have typed props
Tailwind CSS	v4.3+	CSS-first config via @theme in src/tokens/tokens.css
Storybook	10.x	Component dev, docs, visual testing, MCP addon
clsx + tailwind-merge	latest	Combined as cn() in src/lib/utils.ts
ESLint + Prettier	latest	With prettier-plugin-tailwindcss for class ordering

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Design Tokens

All design tokens live in src/tokens/tokens.css as a @theme block. This is the single source of truth. Do not hardcode colour values, radii, or shadows anywhere else.

Use Tailwind utilities (bg-primary, text-error, rounded-default, etc.) or CSS variables (var(--color-primary)) when utilities don't cover the case.

Token naming convention:

• Colours: --color-{name} (e.g., --color-primary, --color-text-secondary)
• Radii: --radius-{size} (e.g., --radius-default, --radius-lg)
• Shadows: --shadow-{size} (e.g., --shadow-default, --shadow-md)

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Component Conventions

File Structure

Each component lives in its own directory:

src/components/ui/Button/
  Button.tsx           — Component implementation
  Button.stories.tsx   — Storybook stories
  index.ts             — Barrel export

Component Taxonomy

• src/components/ui/ — Primitive components (Button, Input, Card, Badge)
• src/components/composite/ — Composed components (StatusMessage, TabBar)
• src/components/layout/ — Layout components (AppShell, Sidebar)

TypeScript

• Export a named props interface: ButtonProps, CardProps, etc.
• Use React.forwardRef for components that wrap native elements.
• Extend native element props where appropriate (e.g., ButtonHTMLAttributes<HTMLButtonElement>).

Styling

• Use Tailwind utility classes as the primary styling method.
• Use the cn() utility from @/lib/utils for conditional classes.
• Never use inline styles except for truly dynamic values.
• Never use CSS modules or styled-components.

Stories

• Every component MUST have a Storybook story file.
• Include at minimum: a Default story, and stories for each significant variant/state.
• Use Storybook Controls for interactive prop exploration.
• Use tags: ['autodocs'] for automatic documentation generation.

Accessibility

• All interactive components must be keyboard-navigable.
• Use semantic HTML elements (<button>, <nav>, <main>, not <div onClick>).
• Include aria- attributes where needed.
• Storybook a11y addon is configured — check for violations.

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Code Patterns

Conditional Classes

import { cn } from '@/lib/utils'

<button className={cn(
  'px-4 py-2 rounded-default font-medium',
  variant === 'primary' && 'bg-primary text-white hover:bg-primary-hover',
  variant === 'secondary' && 'bg-surface border border-border text-text',
  disabled && 'opacity-50 cursor-not-allowed',
)}>

Barrel Exports

Every component directory has an index.ts:

export { Button } from './Button'
export type { ButtonProps } from './Button'

Path Alias

Use @/ for imports from src/:

import { cn } from '@/lib/utils'

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MCP Integrations

MCP servers are configured via claude mcp add (stored in ~/.claude.json) or .mcp.json in the project root. Do not put mcpServers in .claude/settings.json or .claude/settings.local.json — Claude Code ignores MCP config in those files.

• Figma MCP — Official Figma Remote MCP server at https://mcp.figma.com/mcp. Uses HTTP transport with OAuth authentication. Add via: claude mcp add --scope user --transport http figma https://mcp.figma.com/mcp, then authenticate when prompted. Project file: https://www.figma.com/design/mrabO6AtxN3ektGiTk0I9c/ResearchInsights (file key: mrabO6AtxN3ektGiTk0I9c).
• Storybook MCP — runs at localhost:6006/mcp alongside the Storybook dev server. Provides component docs, story generation, and a11y testing. Add via: claude mcp add --transport http storybook http://localhost:6006/mcp

Design-to-Code Workflow

1. Use Figma MCP get_design_context to inspect a selected component or frame
2. Use get_variable_defs to extract design variables (colours, typography, spacing)
3. Map variables to design tokens in src/tokens/tokens.css
4. Build React component using design tokens
5. Verify in Storybook that the component matches the Figma design

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Reference Project

The existing synthesiser at ../SDC-Synthesiser/ contains the UI patterns, design tokens, and component designs this system is based on. Consult it when building components that map to the existing interface.

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Useful Subagents and Tools

• Explore agent — for codebase research spanning multiple files
• webapp-testing skill — for browser-based UI testing via Playwright
• WebSearch/WebFetch — for checking latest library documentation before making dependency decisions
• Storybook MCP — for AI-assisted story generation and component verification