Rolldown

The same options as the Vite plugin. The plugin declares Rolldown hook filters, so files that never name a macro module are skipped in Rust and the JavaScript plugin is not even called for them.

// rolldown.config.ts
import process from 'node:process'
import { fileURLToPath } from 'node:url'
import { i18n } from 'best-i18n/rolldown'

export default {
  input: 'src/main.ts',
  plugins: [
    i18n({
      messagesDir: fileURLToPath(new URL('./messages', import.meta.url)),
      locales: ['en', 'zh'],
      baseLocale: 'en',
      staticLocale: process.env.I18N_STATIC_LOCALE,
    }),
  ],
}

This covers Rolldown used directly and tools built on it (tsdown, ...). In watch mode the catalog reloads per rebuild, and the catalog files are registered as watch dependencies.

Note: rolldown-vite is not this — it keeps the Vite plugin API, so it takes best-i18n/vite unchanged.