# Storybook Contract — Veza Design System

## Purpose

This document defines the mandatory structure and conventions for all Storybook stories in the Veza frontend. It is referenced by `.cursorrules` and must be followed by all contributors and AI assistants.

## Story Requirements

### 1. Feature Components

Every **Feature component** (components in `src/features/`) must have the following story variants:

| Story Name | Description | Required |
|---|---|---|
| `Default` | Component with typical data | Yes |
| `Loading` | Component in loading state (using Skeleton components) | Yes |
| `Error` | Component displaying an error fallback | Yes |
| `Empty` | Component with no data (empty list/state) | Yes, if applicable |

### 2. UI Components

Every **UI component** (components in `src/components/ui/`) must have:

| Story Name | Description | Required |
|---|---|---|
| `Default` | Default variant/state | Yes |
| `Variants` | All visual variants (size, color, etc.) | If applicable |
| `Disabled` | Disabled state | If applicable |
| `WithIcon` | With icon prop | If applicable |

### 3. Layout Components

Layout components (`src/components/layout/`) should demonstrate:

- Responsive behavior (mobile, tablet, desktop)
- Light and dark modes

## Decorators

### Global Decorator

All stories automatically receive the global `StorybookDecorator` configured in `.storybook/preview.tsx`. This provides:

- Theme provider (dark/light mode)
- i18n provider
- Router context (MemoryRouter)
- Toast provider
- MSW request interception

### Do NOT Import Application Providers

Never import application-level providers directly in stories:

```tsx
// BAD — do not do this
import { AuthProvider } from '@/providers/AuthProvider';
export const MyStory = () => (
  <AuthProvider>
    <MyComponent />
  </AuthProvider>
);

// GOOD — the global decorator handles providers
export const MyStory = () => <MyComponent />;
```

## Data Mocking

### Use MSW Handlers

All API data should be mocked via MSW handlers in `src/mocks/handlers.ts`:

```tsx
// In the story file
import type { Meta, StoryObj } from '@storybook/react';
import { http, HttpResponse } from 'msw';

const meta: Meta<typeof MyComponent> = {
  component: MyComponent,
  parameters: {
    msw: {
      handlers: [
        http.get('*/api/v1/my-endpoint', () => {
          return HttpResponse.json({
            success: true,
            data: { items: [] },
          });
        }),
      ],
    },
  },
};
```

### Loading States

Use `delay: 'infinite'` in MSW handlers to simulate loading:

```tsx
export const Loading: StoryObj<typeof MyComponent> = {
  parameters: {
    msw: {
      handlers: [
        http.get('*/api/v1/my-endpoint', async () => {
          await new Promise(() => {}); // Never resolves
        }),
      ],
    },
  },
};
```

### Error States

Return error responses from MSW handlers:

```tsx
export const Error: StoryObj<typeof MyComponent> = {
  parameters: {
    msw: {
      handlers: [
        http.get('*/api/v1/my-endpoint', () => {
          return HttpResponse.json(
            { success: false, error: { message: 'Server error' } },
            { status: 500 },
          );
        }),
      ],
    },
  },
};
```

## File Naming Convention

- Story files: `ComponentName.stories.tsx`
- Co-located with their component file
- Example: `src/components/ui/button.tsx` → `src/components/ui/button.stories.tsx`

## Story File Template

```tsx
import type { Meta, StoryObj } from '@storybook/react';
import { MyComponent } from './MyComponent';

const meta: Meta<typeof MyComponent> = {
  title: 'Features/MyFeature/MyComponent',
  component: MyComponent,
  tags: ['autodocs'],
};

export default meta;
type Story = StoryObj<typeof MyComponent>;

export const Default: Story = {
  args: {
    // Default props
  },
};

export const Loading: Story = {
  // Loading state configuration
};

export const Error: Story = {
  // Error state configuration
};

export const Empty: Story = {
  // Empty state configuration
};
```