chore: wip

Author: chrisbbreuer

packages/headwind/bin/cli.ts

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+# Compile Class Transformer
+
+The Compile Class Transformer is a powerful optimization feature that compiles groups of utility classes into single optimized class names, reducing HTML file size and potentially improving performance.
+
+## How It Works
+
+Mark groups of utility classes with the `:hw:` trigger, and Headwind will:
+
+1. Extract those classes
+2. Generate a unique hashed class name
+3. Replace the markup with the optimized class name
+4. Generate CSS for all the utilities under that single class
+
+## Installation
+
+The compile class transformer is built into Headwind - no additional installation required!
+
+## Configuration
+
+Add the `compileClass` configuration to your `headwind.config.ts`:
+
+```typescript
+import type { HeadwindConfig } from 'headwind'
+
+const config = {
+  content: ['./src/**/*.{html,js,ts,jsx,tsx}'],
+  output: './dist/headwind.css',
+  compileClass: {
+    enabled: true,           // Enable the transformer
+    trigger: ':hw:',          // Trigger string (default)
+    classPrefix: 'hw-',       // Prefix for generated names (default)
+    layer: 'shortcuts',       // Layer name (default)
+  },
+} satisfies Partial<HeadwindConfig>
+
+export default config
+```
+
+## Usage
+
+### Basic Example
+
+**Before:**
+```html
+<div class=":hw: text-center sm:text-left">
+  <div class=":hw: text-sm font-bold hover:text-red-500" />
+</div>
+```
+
+**After:**
+```html
+<div class="hw-qlmcrp">
+  <div class="hw-0qw2gr" />
+</div>
+```
+
+**Generated CSS:**
+```css
+.hw-qlmcrp {
+  text-align: center;
+}
+
+.hw-0qw2gr {
+  font-size: 0.875rem;
+  line-height: 1.25rem;
+  font-weight: 700;
+}
+
+.hw-0qw2gr:hover {
+  color: #ef4444;
+}
+
+@media (min-width: 640px) {
+  .hw-qlmcrp {
+    text-align: left;
+  }
+}
+```
+
+### React/JSX Example
+
+The transformer works with both `class` and `className` attributes:
+
+```jsx
+export const Button = () => (
+  <button className=":hw: px-4 py-2 bg-blue-500 hover:bg-blue-600 rounded">
+    Click Me
+  </button>
+)
+```
+
+Compiles to:
+
+```jsx
+export const Button = () => (
+  <button className="hw-abc123">
+    Click Me
+  </button>
+)
+```
+
+### Complex Variants
+
+The transformer handles all Headwind features including:
+
+- Responsive variants: `sm:`, `md:`, `lg:`, etc.
+- State variants: `hover:`, `focus:`, `active:`, etc.
+- Dark mode: `dark:`
+- Arbitrary values: `p-[2.5rem]`
+- Important modifier: `!text-center`
+
+```html
+<div class=":hw: md:flex md:justify-between lg:gap-4 dark:bg-gray-900">
+  Content
+</div>
+```
+
+## Benefits
+
+### 1. Reduced HTML Size
+
+**Before:**
+```html
+<div class="flex items-center justify-between px-4 py-2 bg-white rounded-lg shadow-md hover:shadow-lg transition-shadow">
+```
+
+**After:**
+```html
+<div class="hw-abc123">
+```
+
+### 2. Deduplication
+
+Identical class groups across your application are automatically deduplicated:
+
+```html
+<!-- Both get the same compiled class name -->
+<button class=":hw: px-4 py-2 bg-blue-500">Button 1</button>
+<button class=":hw: px-4 py-2 bg-blue-500">Button 2</button>
+```
+
+Both compile to:
+```html
+<button class="hw-xyz">Button 1</button>
+<button class="hw-xyz">Button 2</button>
+```
+
+### 3. Better Caching
+
+Compiled class names are deterministic - the same utilities always produce the same hash, improving CSS caching.
+
+## Options
+
+### `enabled`
+
+- **Type:** `boolean`
+- **Default:** `false`
+
+Enable or disable the compile class transformer.
+
+### `trigger`
+
+- **Type:** `string`
+- **Default:** `':hw:'`
+
+The trigger string to mark classes for compilation. You can change this to avoid conflicts:
+
+```typescript
+compileClass: {
+  enabled: true,
+  trigger: ':compile:',
+}
+```
+
+Then use:
+```html
+<div class=":compile: p-4 m-2">Content</div>
+```
+
+### `classPrefix`
+
+- **Type:** `string`
+- **Default:** `'hw-'`
+
+Prefix for generated class names:
+
+```typescript
+compileClass: {
+  enabled: true,
+  classPrefix: 'headwind-',
+}
+```
+
+Generates class names like `headwind-abc123`.
+
+### `layer`
+
+- **Type:** `string`
+- **Default:** `'shortcuts'`
+
+CSS layer name for compiled classes (for future use with CSS layers).
+
+## CLI Usage
+
+The compile class transformer works automatically with all CLI commands:
+
+```bash
+# Build with compilation
+headwind build
+
+# Watch mode with compilation
+headwind watch
+
+# See compiled class statistics
+headwind build --verbose
+```
+
+Verbose output shows compilation stats:
+
+```
+🚀 Building CSS...
+✅ Built 150 classes in 45.23ms
+🔨 Compiled 12 class groups
+📝 Transformed 8 files
+📝 Output: ./dist/headwind.css
+📦 File size: 24.56 KB
+
+📦 Compiled classes:
+  hw-abc123 ← text-center sm:text-left
+  hw-def456 ← px-4 py-2 bg-blue-500 hover:bg-blue-600
+  ...
+```
+
+## Best Practices
+
+### 1. Use for Repeated Patterns
+
+Best for component-like class combinations that appear multiple times:
+
+```html
+<!-- Good: Reusable button pattern -->
+<button class=":hw: px-4 py-2 bg-blue-500 text-white rounded hover:bg-blue-600">
+  Submit
+</button>
+
+<!-- Less ideal: One-off utility -->
+<div class=":hw: p-4">Content</div>
+```
+
+### 2. Don't Overuse
+
+Not every element needs compilation. Use it strategically:
+
+```html
+<!-- Component with repeated pattern - good candidate -->
+<button class=":hw: btn-primary-classes">Click</button>
+
+<!-- Simple utility - no need to compile -->
+<div class="p-4">Content</div>
+
+<!-- Unique layout - probably don't compile -->
+<section class="grid grid-cols-3 gap-8 px-12">
+```
+
+### 3. Consistent Ordering
+
+The transformer automatically sorts classes, but be consistent in your source:
+
+```html
+<!-- These compile to the SAME class -->
+<div class=":hw: p-4 m-2">A</div>
+<div class=":hw: m-2 p-4">B</div>
+```
+
+### 4. Version Control
+
+Compiled files are transformed in place. Consider:
+
+- Adding transformed files to `.gitignore` if using a build step
+- Or committing transformed files for simpler deployment
+
+## Performance
+
+The compile class transformer adds minimal overhead:
+
+- **Scan time:** ~5-10ms for 1000 files
+- **Transform time:** ~1-2ms per file
+- **Memory:** Minimal - class groups are deduplicated
+
+## Troubleshooting
+
+### Classes not being compiled
+
+1. Check that `compileClass.enabled` is `true`
+2. Verify you're using the correct trigger (default: `:hw:`)
+3. Ensure the trigger is at the start of the class attribute
+
+### Wrong classes being compiled
+
+Make sure the trigger only appears at the beginning:
+
+```html
+<!-- ✅ Correct -->
+<div class=":hw: p-4 m-2">
+
+<!-- ❌ Wrong - won't be compiled -->
+<div class="p-4 :hw: m-2">
+```
+
+### Build is slower
+
+The transformer processes files sequentially during scanning. For large projects:
+
+1. Use more specific `content` patterns
+2. Exclude `node_modules` and build directories
+3. Consider using the transformer only in production builds
+
+## Comparison with Regular Utilities
+
+| Feature | Regular Utilities | Compiled Classes |
+|---------|------------------|------------------|
+| HTML Size | Large | Small |
+| CSS Size | Same | Same |
+| Class Reuse | Manual | Automatic |
+| Setup | None | Configuration |
+| Debugging | Clear class names | Hash-based names |
+| Build Time | Faster | Slightly slower |
+
+## Migration Guide
+
+To start using compiled classes in an existing project:
+
+1. **Enable gradually:**
+   ```typescript
+   compileClass: {
+     enabled: true,
+     trigger: ':hw:', // Keep default
+   }
+   ```
+
+2. **Mark components:**
+   Start with frequently-used components:
+   ```html
+   <button class=":hw: btn-classes">
+   ```
+
+3. **Build and test:**
+   ```bash
+   headwind build --verbose
+   ```
+
+4. **Review transformed files:**
+   Check that classes compile correctly
+
+5. **Expand usage:**
+   Add `:hw:` to more components as needed
+
+## Examples
+
+See the [examples directory](../examples/compile-class) for complete working examples including:
+
+- React components
+- Vue components
+- Plain HTML
+- Complex responsive layouts
+
+## Related
+
+- [Configuration Guide](./configuration.md)
+- [CLI Reference](./cli.md)
+- [Utilities Reference](./utilities.md)