Vite 8 Rolldown Migrator

A guided migration assistant for moving existing Vite 5/6/7 projects onto Vite 8 with Rolldown, the Rust-based bundler that replaces the Rollup + esbuild duo for both dev and production builds. It targets teams who want the speed gains of Rolldown without manually untangling plugin incompatibilities, config drift, and CSS pipeline changes. Best suited for medium-to-large apps where build times have become painful.

When to use it

• Your production build runs Rollup and you want to switch to the rolldown-vite package (or the native bundler path in Vite 8).
• You have a vite.config.ts with several @rollup/plugin-* entries and aren't sure which survive the move.
• CI build times or local cold starts have grown and you want Oxc-powered transforms and Lightning CSS minification.
• You're evaluating whether your dependency tree (especially Rollup-only plugins and commonjs interop) is Rolldown-ready before committing.

What it does

The skill inspects your package.json and vite.config.*, then performs the migration in stages:

• Swaps vite for the rolldown-vite drop-in (aliased via overrides/resolutions) or wires up the native bundler depending on your Vite 8 channel.
• Audits plugins: [], flagging Rollup plugins with no Rolldown equivalent and rewriting build.rollupOptions (input/output/manualChunks) into the supported shape.
• Enables experimental.enableNativePlugin where your plugins are compatible, routing transforms through Oxc instead of Babel/esbuild.
• Switches CSS handling to Lightning CSS via css.transformer: 'lightningcss' and build.cssMinify: 'lightningcss', reconciling PostCSS-only features.
• Runs a before/after vite build timing comparison and surfaces bundle-size deltas.

Usage example

curl -fsSL --create-dirs -o ~/.claude/skills/vite-8-rolldown-bundler/SKILL.md https://claudeskil.com/skills/vite-8-rolldown-bundler/SKILL.md

# then, in your project:
claude "migrate this app to Vite 8 + Rolldown and report build-time deltas"

Resulting config sketch:

// vite.config.ts
import { defineConfig } from 'vite'
export default defineConfig({
  experimental: { enableNativePlugin: true },
  css: { transformer: 'lightningcss' },
  build: {
    cssMinify: 'lightningcss',
    rollupOptions: { output: { manualChunks: { vendor: ['react', 'react-dom'] } } },
  },
})

Tips & gotchas

• rolldown-vite is a package alias — pin it through overrides (npm/pnpm) or resolutions (yarn) so transitive deps don't pull plain vite.
• Lightning CSS does not run your PostCSS plugin chain; if you rely on postcss-nesting or custom plugins, keep the PostCSS transformer for those files.
• manualChunks as a function still works, but advanced Rollup output hooks may behave differently under Rolldown — verify chunk graphs after migrating.
• Oxc is stricter about certain decorator/legacy syntax than Babel; expect to adjust tsconfig targets.

FAQ

Is rolldown-vite production-ready? It's the supported way to try Rolldown today and is API-compatible with Vite's config; treat the build output as you would any major-version bump and run your full test suite.

Will my Rollup plugins keep working? Many do via the compatibility layer, but native-plugin mode only accepts Rolldown-aware plugins. The skill lists which of yours need replacing.

Can I roll back? Yes — removing the alias and reverting the config restores standard Vite.