unjs-fontaine

name	unjs-fontaine
description	ALWAYS use when writing code importing "fontless". Consult for debugging, best practices, or modifying fontless, fontaine.
metadata	{"version":"0.2.1"}

unjs/fontaine fontless

Version: 0.2.1 (today) Deps: consola@^3.4.2, css-tree@^3.1.0, defu@^6.1.4, esbuild@^0.27.0, jiti@^2.6.1, lightningcss@^1.30.2, magic-string@^0.30.21, ohash@^2.0.11, pathe@^2.0.3, ufo@^1.6.1, unifont@^0.7.4, unstorage@^1.17.1, fontaine@0.8.0 Tags: latest: 0.2.1 (today)

References: package.json • README • GitHub Issues • GitHub Discussions • Releases

Search

Use npx -y skilld search instead of grepping .skilld/ directories — hybrid semantic + keyword search across all indexed docs, issues, and releases.

npx -y skilld search "query" -p fontless
npx -y skilld search "issues:error handling" -p fontless
npx -y skilld search "releases:deprecated" -p fontless

Filters: docs:, issues:, releases: prefix narrows by source type.

API Changes

⚠️ fontaine → fontless — the package was renamed/extracted; import { fontless } from "fontless" not "fontaine". The fontaine package still exists but only provides font metrics utilities, not the Vite plugin source

✨ fontless() — new Vite plugin export in v0.1.0, replaces old FontaineTransform() from fontaine. Usage: import { fontless } from 'fontless' source

✨ npm provider — v0.2.1 added support for resolving fonts from local npm packages via providers: { npm: true } source

✨ defaults.formats — v0.2.0 added formats option to control resolved font formats. Defaults to ['woff2'] source

✨ providerOptions — v0.2.0 added per-family providerOptions field to pass provider-specific options (e.g. { google: { ... } }) when resolving a font source

⚠️ experimental.processCSSVariables — deprecated, use top-level processCSSVariables instead. Setting to true is no longer needed for Tailwind v4 source

✨ processCSSVariables — promoted from experimental to top-level option. Accepts boolean | 'font-prefixed-only' (default: 'font-prefixed-only') source

✨ createResolver() — exported utility for programmatic font resolution outside the Vite plugin. Takes ResolverContext, returns Promise<Resolver> source

✨ transformCSS() — exported utility to transform CSS with font injection. Used internally by the plugin, available for custom integrations source

✨ DEFAULT_CATEGORY_FALLBACKS — category-aware fallback presets (sans-serif, serif, monospace, cursive, fantasy, system-ui, etc.) re-exported from fontaine. Configure via defaults.fallbacks source

⚠️ unifont v0.7 — v0.2.0 upgraded to unifont v0.7; provider type signatures changed. Custom ProviderFactory implementations may need updates source

Best Practices

✅ Set defaults.formats to ['woff2'] (the default) — google provider previously included both woff2 and woff, causing browsers to download the larger woff file unnecessarily source

✅ Use processCSSVariables: 'font-prefixed-only' (default) for Tailwind v4 — fontless detects --font-* CSS variables in @theme blocks. Setting true is no longer needed or recommended; the old experimental.processCSSVariables is deprecated source

/* Tailwind v4: detected automatically with default config */
@theme {
  --font-sans: 'DM Sans', sans-serif;
}

✅ Set provider: 'none' on self-hosted fonts to skip provider resolution — prevents fontless from searching all providers for fonts you load manually source

fontless({
  families: [
    { name: 'Custom Font', provider: 'none' },
    { name: 'My Font', src: '/fonts/my-font.woff2' },
  ]
})

✅ Use priority array to control provider resolution order — fontless checks providers sequentially and stops at first match. Put your preferred CDN first to avoid unexpected provider selection source

fontless({
  priority: ['bunny', 'google'], // bunny checked before google
})

✅ Override defaults.fallbacks per generic family, not globally — category-aware presets (from fontaine) provide optimized system font stacks per category (sans-serif, serif, monospace, etc.). Only override the specific category you need source

fontless({
  defaults: {
    fallbacks: {
      'sans-serif': ['Arial', 'Helvetica Neue'], // only override sans-serif
      // serif, monospace, etc. keep their optimized defaults
    }
  }
})

✅ Specify weights per family for variable fonts — default is [400] only. Variable fonts that support a weight range won't get their full range unless explicitly configured source

fontless({
  families: [
    { name: 'Inter', weights: ['100..900'] } // variable weight range
  ]
})

✅ Preload is automatic for the highest-priority format but disabled for subsetted fonts — to avoid over-preloading. Override with preload: true on specific families if your subset is small enough source

✅ Use createResolver + transformCSS for non-Vite integrations — fontless exports these as standalone utilities. createResolver returns a function that resolves font families to FontFaceData[], and transformCSS handles CSS injection source

✅ Fonts from npm packages now resolve via the npm provider (v0.2.1) — previously fontless couldn't process fonts imported from node_modules (e.g., fontsource packages). The npm provider was added to handle this source source

✅ Plugin is skipped during vite preview — fontless only runs in dev and build modes. Don't expect font processing in preview source

Related: parcel-bundler-lightningcss, unjs-unifont