@best-i18n/vinext-unprefixed-locale

Serve the default locale unprefixed on vinext - /about and /zh/about, not /en/about - without a proxy rewrite, so default-locale navigations stay cacheable.

app/
  [locale]/          what you write
    layout.tsx
    blog/[...slug]/page.tsx
  (unprefixed)/      what this generates, gitignored
    layout.tsx       → imports [locale]/layout, params.locale pinned to 'en'
    blog/[...slug]/page.tsx

Why

Routes under app/[locale] give every language a prefix. Hiding it for the default locale is usually a proxy that rewrites /about onto /en/about. On vinext that rewrite costs the cache: a rewritten request is resolved rather than requested, and only requested RSC navigations are mapped onto the shared cache key. Every client navigation in the default locale answers Cache-Control: no-store - a Cloudflare BYPASS on every page change - while the prefixed locales hit the cache.

This package removes the rewrite. It mirrors app/[locale] into a route group whose files import the originals and pin the locale, so /about matches a route directly. It is the mirror from @best-i18n/next-unprefixed-locale, run from a Vite plugin and meant for a server.

Setup

pnpm add @best-i18n/vinext-unprefixed-locale

// vite.config.ts
import { unprefixedLocale } from '@best-i18n/vinext-unprefixed-locale'
import vinext from 'vinext'
import { defineConfig } from 'vite'

export default defineConfig({
  plugins: [
    unprefixedLocale({ defaultLocale: 'en', localeParam: 'locale' }),
    vinext(),
  ],
})

The mirror is written when Vite resolves its config, before vinext scans the app directory, and regenerated while vite dev runs whenever a file under [locale] changes. Then take the rewrite out of the proxy.

On a server [locale] still sits at the root, so:

• Redirect /en/... to its unprefixed URL, e.g. with redirects() in next.config.ts.
• Validate the locale in [locale]/layout.tsx and call notFound() for anything else: an unknown single-segment path such as /foo now reaches [locale] as locale: 'foo' instead of being rewritten to /en/foo. Do not use dynamicParams = false for this; it cascades to every segment below.
• Fall back to the default locale where the server reads the locale from the [locale] root param: mirrored routes have no such segment.

Options

| Option | Default | | | ---------------- | --------------------- | ------------------------------------------------------------------------ | | defaultLocale | required | The locale served unprefixed. | | localeParam | 'locale' | Name of the segment: [locale], [lang]. | | appDir | src/app, else app | Relative to the Vite root. | | group | '(unprefixed)' | Where the mirror goes. Must be a route group, so it adds no URL segment. | | pageExtensions | tsx ts jsx js | Which files are routes. | | watch | true | Regenerate in vite dev when files under [locale] change. | | quiet | false | Skip the one-line summary. Warnings are always printed. |

generate(options) is exported too, and there is a CLI for the same:

vinext-unprefixed-locale --locale en          # once
vinext-unprefixed-locale --locale en --watch  # keep going

What is generated

| In [locale] | In the mirror | | -------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | page, layout, template, default | A component rendering the original with params pinned. generateMetadata, generateViewport and generateStaticParams are wrapped the same way; metadata and viewport are re-exported. | | route | One function per HTTP method, context.params pinned, plus generateStaticParams. | | opengraph-image, twitter-image, icon, apple-icon | The default export and generateImageMetadata pinned; alt, size, contentType re-exported. | | loading, error, not-found, global-error | Re-exported as they are; they take no params. | | favicon.ico, icon.png, robots.txt, … | Copied. | | Anything else - components, helpers, styles | Left alone. The wrappers import the originals, which resolve their own neighbours. |

Route segment config - dynamic, revalidate and the rest - is repeated as a literal, because it is read by static analysis and a re-exported binding would not be seen. A 'use client' page gets a 'use client' wrapper. The group carries its own .gitignore.

Limits

• No dynamic segment directly under [locale]. [locale]/[slug] would mirror to /[slug], beside /[locale] at the root, and two dynamic segments with different names cannot share a level.
• Two root layouts. [locale]/layout.tsx and its mirror each render <html>, so switching locale is a full page load.
• export * in a route file hides its exports from the mirror.

License

MIT