From 4e25db2989e40121a82b340d4dde3e826da3ad19 Mon Sep 17 00:00:00 2001
From: Daniel Dietzler <36593685+danieldietzler@users.noreply.github.com>
Date: Mon, 6 Jul 2026 16:42:47 +0200
Subject: [PATCH] fix: chinese browser locales recognition (#29622)

---
 web/src/lib/i18n.spec.ts  |  9 +++++++++
 web/src/lib/utils/i18n.ts | 12 +++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/web/src/lib/i18n.spec.ts b/web/src/lib/i18n.spec.ts
index ccc60a835b..ebf2fdfa3b 100644
--- a/web/src/lib/i18n.spec.ts
+++ b/web/src/lib/i18n.spec.ts
@@ -58,5 +58,14 @@ describe('i18n', () => {
       expect(getClosestAvailableLocale(['sr_Cyrl'], allLocales)).toBe('sr_Cyrl');
       expect(getClosestAvailableLocale(['zh_Hant'], allLocales)).toBe('zh_Hant');
     });
+
+    it('should handle language aliases', () => {
+      const allLocales = ['zh-Hans', 'zh-Hant'];
+      expect(getClosestAvailableLocale(['zh-CN'], allLocales)).toBe('zh-Hans');
+      expect(getClosestAvailableLocale(['zh-HK'], allLocales)).toBe('zh-Hant');
+      expect(getClosestAvailableLocale(['zh-MO'], allLocales)).toBe('zh-Hant');
+      expect(getClosestAvailableLocale(['zh-SG'], allLocales)).toBe('zh-Hans');
+      expect(getClosestAvailableLocale(['zh-TW'], allLocales)).toBe('zh-Hant');
+    });
   });
 });
diff --git a/web/src/lib/utils/i18n.ts b/web/src/lib/utils/i18n.ts
index 85331ddf7c..758721c384 100644
--- a/web/src/lib/utils/i18n.ts
+++ b/web/src/lib/utils/i18n.ts
@@ -13,6 +13,14 @@ export const getFormatter = async () => {
   return get(t);
 };
 
+const aliases: Record<string, string> = {
+  'zh-CN': 'zh-Hans',
+  'zh-HK': 'zh-Hant',
+  'zh-MO': 'zh-Hant',
+  'zh-SG': 'zh-Hans',
+  'zh-TW': 'zh-Hant',
+};
+
 const modules = import.meta.glob('$i18n/*.json');
 
 const fileCodes = Object.keys(modules)
@@ -33,7 +41,9 @@ const getSubLocales = (locale: string) => {
 
 export const getClosestAvailableLocale = (locales: readonly string[], allLocales: readonly string[]) => {
   const allLocalesSet = new Set(allLocales.map((locale) => convertBCP47(locale)));
-  return locales.find((locale) => getSubLocales(locale).some((subLocale) => allLocalesSet.has(subLocale)));
+  return locales
+    .map((locale) => aliases[locale] ?? locale)
+    .find((locale) => getSubLocales(locale).some((subLocale) => allLocalesSet.has(subLocale)));
 };
 
 export const getPreferredLocale = () => getClosestAvailableLocale(navigator.languages, langCodes);