Subdomain only redirects

[Matt-Cain]

Hi 👋 , I am just getting up and running, and I think I may have a misunderstanding about how subdomain redirects work.

Expected:

• When I navigate to local.app.com with Accept-Language: pt-BR;q=0.9
• I should be redirect to pt.local.app.com

Actual:

• When I navigate to local.app.com with Accept-Language: pt-BR;q=0.9
• I am not redirected, but stay on local.app.com
• However, the content on the page shows the correct language

import { defineRouting } from 'next-intl/routing';

export const routing = defineRouting({
  defaultLocale: 'en-US',
  domains: [
    {
      defaultLocale: 'en-US',
      domain: 'en.local.app.com',
      locales: ['en-US'],
    },
    {
      defaultLocale: 'pt-BR',
      domain: 'pt.local.app.com',
      locales: ['pt-BR'],
    },
    {
      defaultLocale: 'es',
      domain: 'es.local.app.com',
      locales: ['es'],
    },
  ],
  localePrefix: { mode: 'never' },
  locales: ['en-US', 'pt-BR', 'es'],
});

When I set localePrefix to { mode: 'always' }, I get redirected properly, albeit prefix-based routing

    "next": "15.3.1",
    "next-intl": "^4.1.0",
    "react": "^19.0.0",

[amannn]

There's this part relevant here from the docs:

If no domain matches, the middleware will fall back to default locale matching based on prefixes (e.g. on localhost, for local development).

If you need additional redirects for local.app.com, you might want to compose the middleware.

Hope this helps!