Motivation

Fix #11433

Docusaurus v3 should maintain a retro-compatible behavior regarding where it output files.
The new v3.9 i18n features implemented in #11316 broke that contract.

When a site has a baseUrl: '/myBaseUrl/', then the files should be written

• in /build/ and /build/fr/
• not /build/myBaseUrl/ and /build/myBaseUrl/fr/

Note that in the future, we'll probably want to expose a new i18n outDir config for each locale because it makes sense to 100% decouple the locale baseUrl from its outDir. It's possible to assemble things and rewrite URLs at the CDN level, so we only do a best effort to infer a decent outDir for each locale, but ultimately we should give total freedom to the user.

Note that in the current state, there are cases where it's really hard to infer a decent outDir for a locale, such as this one:

module.exports = {
  title: 'Hello',
  baseUrl: '/myBaseUrl/',
  url: 'https://docusaurus.io',
  i18n: {
    defaultLocale: 'en',
    locales: ['en','fr', 'de','it'],
    localeConfigs: {
      en: {
        baseUrl: '/myBaseUrl/',
      },
      fr: {
        baseUrl: '/myBaseUrl/fr/',
      },
      de {
        baseUrl: '/somethingElse/de/',
      },
    }
  }
};

In this case, de does not start with /myBaseUrl/, but we can't output outside of the root build folder so this means we'll have as out dirs:

• en => build
• fr => build/fr
• de => build/somethingElse/de

This creates an ambiguity where different baseUrls can be mapped to the same outDir, and may complicate deployments in such situations. Fortunately, this config was only introduced in v3.9, and most users will not do that, so I doubt it will be a problem in 99% of the cases, but it still further motivates the ability to provide an explicit localeConfig.outDir value.

Test Plan

local tests + CI snapshots