# Atomic Design Architecture Reference

Enterprise-scale UI Kit organization using Atomic Design methodology for Pencil.

## Overview

**Problem**: Large monolithic `.pen` files (5000+ lines) cause:
- ❌ Slow performance (2-3 second load times)
- ❌ Maintenance challenges (duplicate components)
- ❌ Collaboration bottlenecks (merge conflicts)
- ❌ Poor reusability
- ❌ Difficult to scale for enterprise applications

**Solution**: Atomic Design Hierarchy - Industry standard for enterprise UI Kits

## Atomic Design Structure

```
project-name/
├── src/
│   ├── foundations/
│   │   └── design-tokens.pen           # Design system variables
│   │
│   ├── atoms/                          # Smallest building blocks
│   │   ├── buttons.pen                 # All button variants & states
│   │   ├── inputs.pen                  # Text fields, checkboxes, radio
│   │   ├── badges.pen                  # Badges, chips, pills, tags
│   │   ├── icons.pen                   # Icon library (if custom)
│   │   └── typography.pen              # Headings, body text, labels
│   │
│   ├── molecules/                      # Combinations of atoms
│   │   ├── form-fields.pen             # Label + Input + Error
│   │   ├── search-bar.pen              # Input + Icon + Button
│   │   ├── card-headers.pen            # Icon + Title + Badge
│   │   └── navigation-items.pen        # Icon + Text + Badge
│   │
│   ├── organisms/                      # Complex UI sections
│   │   ├── cards.pen                   # Feature, pricing, step cards
│   │   ├── navigation.pen              # Top nav, sidebar, mobile menu
│   │   ├── headers.pen                 # Page & section headers
│   │   ├── footers.pen                 # Footer variants
│   │   └── forms.pen                   # Complete form layouts
│   │
│   ├── templates/                      # Page layouts (optional)
│   │   ├── dashboard-layout.pen
│   │   ├── landing-layout.pen
│   │   └── auth-layout.pen
│   │
│   └── pages/                          # Complete pages
│       ├── desktop-home.pen
│       ├── mobile-home.pen
│       └── tablet-home.pen
│
├── build/                              # Build output (gitignore)
├── scripts/
│   └── build.py                        # Build script
├── pencil.config.json
└── USAGE_GUIDE.md
```

## Why Atomic Design?

### Benefits

- ✅ **Industry Standard** - Used by Figma, Material Design, Ant Design
- ✅ **Maximum Scalability** - Easy to add components at any level
- ✅ **Clear Hierarchy** - Atoms → Molecules → Organisms → Templates → Pages
- ✅ **Team Collaboration** - Different designers own different atomic levels
- ✅ **Reusability** - Components compose naturally from smaller pieces
- ✅ **Discoverability** - Intuitive folder structure for finding components
- ✅ **Maintainability** - Small, focused files (<500 lines each)
- ✅ **Version Control** - Minimal merge conflicts with parallel work

### Recommended For

- ✅ Enterprise applications with 50+ components
- ✅ Design systems shared across multiple products
- ✅ Teams of 3+ designers working in parallel
- ✅ Long-term maintenance (2+ years)
- ✅ Component documentation & showcases
- ✅ Cross-platform design consistency

## Component Naming Convention

Atomic Design uses strict hierarchical naming:

```
{AtomicLevel}/{Component}/{Variant}/{State}
```

### Atoms (Smallest Building Blocks)

```
Atom/Button/Primary/Default
Atom/Button/Primary/Hover
Atom/Button/Primary/Disabled
Atom/Button/Secondary/Default
Atom/Badge/Section/Default
Atom/Input/Text/Default
Atom/Input/Text/Error
Atom/Input/Text/Disabled
```

### Molecules (Combinations of Atoms)

```
Molecule/FormField/Text/Default
Molecule/FormField/Text/WithError
Molecule/SearchBar/Default
Molecule/SearchBar/Focused
Molecule/CardHeader/WithIcon
Molecule/CardHeader/Plain
```

### Organisms (Complex UI Sections)

```
Organism/Card/Feature/Default
Organism/Card/Pricing/Enterprise
Organism/Navigation/Desktop/Default
Organism/Navigation/Mobile/Collapsed
Organism/Navigation/Mobile/Expanded
Organism/Footer/TwoColumn/Default
Organism/Footer/FourColumn/Default
```

### Naming Rules

1. ✅ **Always include atomic level** (Atom/Molecule/Organism)
2. ✅ **Use PascalCase** for all parts
3. ✅ **Include variant** even if only one exists (use "Default")
4. ✅ **Add state** for interactive components (Default/Hover/Active/Focus/Disabled/Loading)
5. ✅ **Be descriptive** - Name should explain purpose without seeing component

## Component States & Variants

### Interactive Component States

Every interactive component should have states:

```
Button/Primary/
├── Default        # Resting state
├── Hover          # Mouse over
├── Active         # Pressed/clicked
├── Focus          # Keyboard focus
├── Disabled       # Non-interactive
└── Loading        # Processing state (with spinner)
```

### Implementation Example

```json
// Default state
{
  "type": "frame",
  "id": "BtnPrimary_Default",
  "name": "Atom/Button/Primary/Default",
  "reusable": true,
  "fill": {
    "type": "gradient",
    "colors": [
      {"color": "#FF5C00", "position": 0},
      {"color": "#FF8A4C", "position": 1}
    ]
  }
}

// Hover state - slightly brighter
{
  "type": "frame",
  "id": "BtnPrimary_Hover",
  "name": "Atom/Button/Primary/Hover",
  "reusable": true,
  "fill": {
    "type": "gradient",
    "colors": [
      {"color": "#FF6E1A", "position": 0},
      {"color": "#FF9C66", "position": 1}
    ]
  }
}

// Disabled state - reduced opacity
{
  "type": "frame",
  "id": "BtnPrimary_Disabled",
  "name": "Atom/Button/Primary/Disabled",
  "reusable": true,
  "fill": "#6B6B70",
  "opacity": 0.5
}
```

### Responsive Variants

```
Organism/Navigation/
├── Desktop/
│   ├── Default        # Full horizontal nav with all items
│   └── Scrolled       # Sticky/collapsed on scroll
├── Tablet/
│   ├── Default        # Hybrid with some collapsed items
│   └── MenuOpen       # Sidebar drawer
└── Mobile/
    ├── Collapsed      # Hamburger icon only
    └── Expanded       # Full-screen menu overlay
```

## Design Tokens Foundation

### design-tokens.pen Structure

```json
{
  "version": "2.6",
  "children": [{
    "type": "frame",
    "name": "Design Tokens Reference",
    "layout": "vertical",
    "gap": 20,
    "children": [
      {
        "type": "text",
        "content": "Design System Tokens",
        "fontSize": 32,
        "fill": "$text-primary"
      }
    ]
  }],
  "variables": {
    // Colors - Semantic naming
    "bg-page": {"type": "color", "value": "#0A0A0B"},
    "bg-surface": {"type": "color", "value": "#1A1A1C"},
    "bg-elevated": {"type": "color", "value": "#222225"},
    "text-primary": {"type": "color", "value": "#FFFFFF"},
    "text-secondary": {"type": "color", "value": "#ADADB0"},
    "text-tertiary": {"type": "color", "value": "#8B8B90"},
    "orange-primary": {"type": "color", "value": "#FF5C00"},
    "orange-light": {"type": "color", "value": "#FF8A4C"},
    "border-default": {"type": "color", "value": "#3B3B40"},
    "border-subtle": {"type": "color", "value": "#27272A"},
    
    // Typography
    "font-primary": {"type": "string", "value": "Roboto"},
    "text-xs": {"type": "number", "value": 11},
    "text-sm": {"type": "number", "value": 13},
    "text-base": {"type": "number", "value": 14},
    "text-lg": {"type": "number", "value": 16},
    "text-xl": {"type": "number", "value": 18},
    "text-2xl": {"type": "number", "value": 24},
    "text-3xl": {"type": "number", "value": 32},
    
    // Spacing (8px grid)
    "space-1": {"type": "number", "value": 4},
    "space-2": {"type": "number", "value": 8},
    "space-3": {"type": "number", "value": 12},
    "space-4": {"type": "number", "value": 16},
    "space-5": {"type": "number", "value": 20},
    "space-6": {"type": "number", "value": 24},
    "space-8": {"type": "number", "value": 32},
    "space-10": {"type": "number", "value": 40},
    
    // Border Radius
    "radius-sm": {"type": "number", "value": 6},
    "radius-md": {"type": "number", "value": 10},
    "radius-lg": {"type": "number", "value": 16},
    "radius-full": {"type": "number", "value": 100},
    
    // Breakpoints
    "breakpoint-mobile": {"type": "number", "value": 390},
    "breakpoint-tablet": {"type": "number", "value": 768},
    "breakpoint-desktop": {"type": "number", "value": 1440}
  }
}
```

## Extraction Workflow

### Step 1: Audit Components

```bash
# Analyze current structure
grep '"name":' tPOS-ui-kit.pen | grep -i "button" > buttons-list.txt
grep '"name":' tPOS-ui-kit.pen | grep -i "badge" > badges-list.txt
grep '"name":' tPOS-ui-kit.pen | grep -i "card" > cards-list.txt

# Count components by category
echo "Buttons: $(grep -c button buttons-list.txt)"
echo "Badges: $(grep -c badge badges-list.txt)"
echo "Cards: $(grep -c card cards-list.txt)"
```

### Step 2: Create Structure

```bash
mkdir -p src/foundations src/atoms src/molecules src/organisms src/pages
```

### Step 3: Extract to Atomic Files

The `pencil-design` skill now includes an automated extraction tool.

```bash
# Run the extraction script
python3 scripts/extract-atomic.py
```

This script will:
1. Read `src/components/tPOS-ui-kit.pen` (or configured library)
2. Extract design tokens to `src/foundations/design-tokens.pen`
3. Categorize components into `src/atoms`, `src/molecules`, `src/organisms`
4. Generate showcase wrappers for each file

**Customization**:
Edit `scripts/extract-atomic.py` to adjust categorization logic (regex patterns) if your component names differ.

### Step 4: Create Showcase Files

```python
import json
from pathlib import Path

for atomic_dir in ['src/atoms', 'src/molecules', 'src/organisms']:
    for filepath in Path(atomic_dir).glob('*.pen'):
        with open(filepath, 'r') as f:
            data = json.load(f)
        
        # Wrap components in a showcase page
        showcase = {
            'type': 'frame',
            'name': f'{filepath.stem.title()} Showcase',
            'width': 1440,
            'fill': '$bg-page',
            'layout': 'vertical',
            'gap': 80,
            'padding': [80, 120],
            'children': data['children']
        }
        
        data['children'] = [showcase]
        
        with open(filepath, 'w') as f:
            json.dump(data, f, indent=2)
        
        print(f'✅ Added showcase to {filepath}')
```

### Step 5: Validate Structure

```python
import json
import os
from pathlib import Path

required_structure = [
    'src/foundations/design-tokens.pen',
    'src/atoms',
    'src/molecules',
    'src/organisms'
]

for path in required_structure:
    if not os.path.exists(path):
        print(f'❌ Missing: {path}')
    else:
        if path.endswith('.pen'):
            with open(path, 'r') as f:
                data = json.load(f)
            assert 'version' in data
            assert 'variables' in data
            print(f'✅ Valid: {path}')
        else:
            files = list(Path(path).glob('*.pen'))
            print(f'✅ {path}: {len(files)} files')

print('\n🎉 Atomic Design structure validated!')
```

## Best Practices

1. **Foundations First** - Design tokens (`design-tokens.pen`) is single source of truth
2. **Build Bottom-Up** - Atoms → Molecules → Organisms → Templates → Pages
3. **Component States** - Every interactive component needs ≥3 states (default/hover/disabled)
4. **Naming Consistency** - Strict format: `{Level}/{Component}/{Variant}/{State}`
5. **File Organization** - Each atomic level in separate folder (`src/atoms/`, `src/molecules/`)
6. **Token Synchronization** - Copy `variables` object from `design-tokens.pen` to all files
7. **Showcase Pages** - Each atomic file needs showcase page to demo components
8. **No Cross-Contamination** - Atoms don't reference molecules, molecules don't reference organisms
9. **Reusable Flag** - Set `"reusable": true` for all reusable components
10. **Responsive Variants** - Create variants for Desktop/Tablet/Mobile (not breakpoint logic in Pencil)
11. **Documentation** - Document component props, states, usage in USAGE_GUIDE.md
12. **Version Control**:
    - Commit: `src/` (all atomic files)
    - Gitignore: `build/` (generated files)
    - Tag releases: `v1.0.0` for breaking changes in design tokens
13. **Component Library** - Update atomic files before building pages
14. **Validation** - Validate JSON structure after extraction
15. **Backup Strategy** - Keep `original.pen.backup` before refactoring to Atomic Design

## Usage Guide Template

```markdown
# [Project] Design System - Atomic Design Structure

## Structure Overview

\`\`\`
src/
├── foundations/
│   └── design-tokens.pen    # Colors, typography, spacing, breakpoints
├── atoms/                   # Smallest building blocks
├── molecules/               # Simple combinations
├── organisms/               # Complex components
└── pages/                   # Complete pages
\`\`\`

## Atomic Levels

### Foundations
- **File**: `design-tokens.pen`
- **Contains**: CSS variables, color palette, typography scale, spacing system
- **Usage**: Copy variables to all component files

### Atoms
- **Examples**: Buttons, inputs, badges, icons, typography
- **Characteristics**: Cannot be broken down further
- **States**: Default, Hover, Active, Disabled

### Molecules
- **Examples**: Form fields, search bars, card headers
- **Characteristics**: Combinations of 2-3 atoms
- **Usage**: Import atoms and compose

### Organisms
- **Examples**: Cards, navigation, headers, footers
- **Characteristics**: Complex sections with multiple molecules
- **Usage**: Complete, reusable UI sections

## Workflow

1. **Update Foundation**: Edit `design-tokens.pen` for colors/typography changes
2. **Build Components**: Edit atomic files with proper naming (Atom/Button/Primary/Default)
3. **Update Library**: Run `python3 scripts/build.py --library` to compile atoms
4. **Compose Up**: Molecules use atoms, organisms use molecules
5. **Test in Pages**: Reference components in page files (from compiled library)
6. **Build Monolith**: Run `python3 scripts/build.py -m` for production output

## Component Naming

\`\`\`
{Level}/{Component}/{Variant}/{State}

Examples:
- Atom/Button/Primary/Default
- Molecule/FormField/Text/WithError
- Organism/Card/Feature/Default
\`\`\`

## Best Practices

1. ✅ **Design Tokens First**: Always update foundation before components
2. ✅ **Build Up**: Atoms → Molecules → Organisms → Pages
3. ✅ **Consistent States**: All interactive components need states
4. ✅ **Reusable**: Set `"reusable": true` on all shareable components
5. ✅ **Version Control**: Commit src/ files, gitignore build/
```

## Resources

- Back to [Pencil Design Skill](../SKILL.md)
- [File Format Reference](./FILE_FORMAT.md)
- [Build System Reference](./BUILD_SYSTEM.md)
- [Code Conversion Reference](./CODE_CONVERSION.md)
- [Atomic Design Book by Brad Frost](https://atomicdesign.bradfrost.com/)
- [Material Design System](https://m3.material.io/)
- [Figma Design Systems](https://www.figma.com/best-practices/design-systems/)
