System wide default language detection via browser language header #1124

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MrUnknownDE · 2026-04-05T18:19:27+02:00

MrUnknownDE commented

2026-04-05 18:19:27 +02:00

Originally created by @Pallavikumarimdb on 8/3/2025

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By creating this pull request, I grant the project maintainers an unlimited,
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choose, including both the AGPLv3 and the Fossorial Commercial license terms. I
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Description

This PR adds support for detecting a user's preferred language from their browser settings (Accept-Language header) and falling back to a predefined default (en-US) when not available. The flow works as follows:

If a cookie exists and its value matches one of the app-supported locales (/i18n/config.ts), it is used.
If not, the Accept-Language header from the browser is parsed.
We extract the base language (e.g., fr from fr-FR).
We try to match it against available locales by comparing prefixes.
If no match is found, the app falls back to the default locale: 'en-US'.

Fixes #1131

How to test?

Open your browser settings and change the preferred language to something like French.
Make sure the NEXT_LOCALE cookie is not set by clearing cookies or using an incognito/private window.
Visit the app in a new tab or incognito window.
Set your browser to a language not included in the app’s locales. The application should fallback to en-US.
Cookie Override Test: If NEXT_LOCALE cookie is set (e.g., via language switcher), it should take priority over browser settings on the next visit.

*Originally created by @Pallavikumarimdb on 8/3/2025* ## Community Contribution License Agreement By creating this pull request, I grant the project maintainers an unlimited, perpetual license to use, modify, and redistribute these contributions under any terms they choose, including both the AGPLv3 and the Fossorial Commercial license terms. I represent that I have the right to grant this license for all contributed content. ## Description This PR adds support for detecting a user's preferred language from their browser settings (Accept-Language header) and falling back to a predefined default (en-US) when not available. The flow works as follows: 1. If a cookie exists and its value matches one of the app-supported locales (/i18n/config.ts), it is used. 2. If not, the Accept-Language header from the browser is parsed. We extract the base language (e.g., fr from fr-FR). We try to match it against available locales by comparing prefixes. 3. If no match is found, the app falls back to the default locale: 'en-US'. Fixes #1131 ## How to test? 1. Open your browser settings and change the preferred language to something like French. 2. Make sure the NEXT_LOCALE cookie is not set by clearing cookies or using an incognito/private window. 3. Visit the app in a new tab or incognito window. 5. Set your browser to a language not included in the app’s locales. The application should fallback to en-US. 6. Cookie Override Test: If NEXT_LOCALE cookie is set (e.g., via language switcher), it should take priority over browser settings on the next visit.

MrUnknownDE closed this issue

2026-04-05 18:19:27 +02:00

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Reference: github/pangolin#1124