## Summary
This PR adds a new `@tailwindcss/webpack` package that provides a
dedicated webpack loader for Tailwind CSS v4. This loader works with
both standard webpack and Turbopack's webpack loader compatibility
layer.
### Why a dedicated loader?
The current webpack integration uses `postcss-loader` +
`@tailwindcss/postcss`. While this works, a dedicated loader:
- **Eliminates PostCSS as a middleman** - works directly with CSS
strings (no AST conversions)
- **Simpler and more efficient** - follows the same pattern as
`@tailwindcss/vite`
- **Better for Turbopack** - gives direct control over dependency
reporting via webpack's loader API
### How it works
The loader mirrors the Vite plugin's approach:
1. Uses `compile()` from `@tailwindcss/node` to parse CSS and resolve
`@apply` directives
2. Uses `Scanner` from `@tailwindcss/oxide` to scan content files for
utility candidates
3. Reports dependencies via `this.addDependency()` and
`this.addContextDependency()`
4. Optionally optimizes output with Lightning CSS
### Usage
```javascript
// webpack.config.js
module.exports = {
module: {
rules: [
{
test: /.css$/i,
use: [
MiniCssExtractPlugin.loader,
'css-loader',
'@tailwindcss/webpack', // No PostCSS needed!
],
},
],
},
}
```
### Options
- `base` - The base directory to scan for class candidates (defaults to
`process.cwd()`)
- `optimize` - Whether to optimize/minify the output CSS (defaults to
`true` in production)
### Files added
- `packages/@tailwindcss-webpack/` - New package
- `src/index.ts` - Main loader implementation
- `src/index.cts` - CommonJS entry point for webpack compatibility
- `package.json`, `tsconfig.json`, `tsup.config.ts`, `README.md`
- `integrations/webpack/loader.test.ts` - Integration tests
- `integrations/utils.ts` - Added webpack override for transitive
dependencies
### Test plan
- [x] Build test - verifies basic compilation
- [x] Watch test - verifies HMR when adding new Tailwind classes
- [x] `@apply` test - verifies `@apply` directives work correctly
- [x] Optimization test - verifies minification works
---------
Co-authored-by: Robin Malfait <malfait.robin@gmail.com>
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## Summary
quotation mark is not closed in README doc of the postcss preprocesor
## Test plan
not needed
This PR adds a bit more information when running the upgrade tool to
know what version of Tailwind CSS you're upgrading from. This will help
users and maintainers when things go wrong.
Will have another PR up soon that errors when the Tailwind CSS version
in package.json and node_modules don't match.
### Test plan
Ran this one one of our older projects and saw the version logged
correctly.
<img width="1055" height="363" alt="image"
src="https://github.com/user-attachments/assets/5cbf4c52-ea0f-42c8-bd55-5bae2ed511de"
/>
Closes https://github.com/tailwindlabs/tailwindcss.com/issues/2061
In lieu of finding a place to put this on the docs we can at least
document this in the readme for the plugin.
---------
Co-authored-by: Philipp Spiess <hello@philippspiess.com>
