v5.0.0

We have reduced dependencies. According to npmx.dev, the number of dependencies has been reduced from 97 to 46.

As a trade-off, this release also includes several breaking changes.

Breaking Changes

Drops support for Node.js 18 / 20 (#295)

Use Node.js 22 or later.

CSS module files starting with . are no longer matched by default (#307)

The internal glob implementation has been changed, and dotfiles are no longer matched by default.

Before: hcm 'src/**/*.module.css' matched both src/a.module.css and src/.hidden.module.css

After: hcm 'src/**/*.module.css' matches only src/a.module.css

To preserve the previous behavior, use a brace expansion to explicitly include dotfiles:

hcm 'src/**/{*,.*}.module.css'

Boolean options no longer accept the --option=true / --option=false syntax (#308)

Use --option / --no-option instead.

Before	After
--cache=false	--no-cache
--cache=true	--cache
--watch=false	--no-watch
--declarationMap=false	--no-declarationMap
--arbitraryExtensions=false	--no-arbitraryExtensions

YAML-based PostCSS config file require yaml package (#316)

If you use a YAML-based PostCSS config file (postcss.config.yaml or postcss.config.yml), you must now install the yaml package separately:

npm install --save-dev yaml

This is because postcss-load-config v6 no longer bundles yaml as a dependency — it is now an optional peer dependency. If yaml is not installed, loading a YAML config file will throw an error.

If you use a JavaScript or TypeScript PostCSS config file (e.g. postcss.config.js, postcss.config.ts), no action is required.

In watch mode, node_modules and .git directories are now always excluded from the watch target, regardless of the pattern (#317)

Due to an update of the internally-used file watcher library and to avoid performance issues caused by scanning large directories, node_modules and .git are now excluded unconditionally. Previously, patterns like hcm 'node_modules/**/*.module.css' --watch would watch files inside node_modules.

In practice, running hcm against node_modules or .git is almost never intended, so this change should not affect most users.

What's Changed

Breaking Change

• feat!: require Node.js ^22.20.0 || ^24.8.0 || >=26.0.0 by @mizdra in #295
• chore!: reduce dependencies by replacing with Node.js built-ins by @mizdra in #307
• chore!: replace yargs with node:util's parseArgs by @mizdra in #308
• deps: update postcss-load-config to v6 by @mizdra in #316
• deps: update chokidar to v5 by @mizdra in #317

Bug

• fix: set Node.js engines requirement on the published package instead of the monorepo root by @mizdra in #300

Documentation

• docs: add AGENTS.md and re-export it from CLAUDE.md by @mizdra in #306

Refactoring

• chore: migrate from Prettier to Oxfmt by @mizdra in #299
• chore: migrate from ESLint to Oxlint by @mizdra in #301
• chore: remove npm workspace and flatten to root by @mizdra in #302

Testing

• Remove custom snapshot serializers by @mizdra in #298
• test: suppress false-positive source map warning from Vite by @mizdra in #310
• test: fix flaky test by @mizdra in #314

Maintenance

• Repository maintenance by @mizdra in #297
• chore: preinstall less v3/v4 and switch via LESS_VERSION env var by @mizdra in #303
• chore: remove unused react and @types/react by @mizdra in #304
• chore: upgrade TypeScript to v6 by @mizdra in #305
• deps: update vitest to v4 by @mizdra in #309
• Run build before update example by @mizdra in #312
• Update devDependencies by @mizdra in #313
• Use Trusted Publishing and Staged Packages by @mizdra in #318

Dependencies

• deps: update dependencies by @mizdra in #315

Other Changes

• Update GitHub Actions by @mizdra in #296

Full Changelog: v4.0.0...v5.0.0