From 9c79bf2198ef27f29fc8f1f84a78f2f33bd7e7be Mon Sep 17 00:00:00 2001
From: plebeius <tom@plebbitlabs.com>
Date: Sun, 8 Mar 2026 21:09:22 +0800
Subject: [PATCH] fix(i18n): default interface language to english

---
 .../__tests__/interface-settings.test.tsx     |  2 +
 .../interface-settings/interface-settings.tsx | 10 ++--
 src/lib/__tests__/init-translations.test.ts   |  8 +++-
 src/lib/constants.ts                          | 44 ++++++++++++++++++
 src/lib/init-translations.ts                  | 46 ++++---------------
 5 files changed, 66 insertions(+), 44 deletions(-)

diff --git a/src/components/settings-modal/interface-settings/__tests__/interface-settings.test.tsx b/src/components/settings-modal/interface-settings/__tests__/interface-settings.test.tsx
index 2ce612bd..ed266f8c 100644
--- a/src/components/settings-modal/interface-settings/__tests__/interface-settings.test.tsx
+++ b/src/components/settings-modal/interface-settings/__tests__/interface-settings.test.tsx
@@ -6,6 +6,7 @@ import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import packageJson from '../../../../../package.json';
 import InterfaceSettings from '../interface-settings';
 import useFeedViewSettingsStore from '../../../../stores/use-feed-view-settings-store';
+import { INTERFACE_LANGUAGE_STORAGE_KEY } from '../../../../lib/constants';
 
 (globalThis as { IS_REACT_ACT_ENVIRONMENT?: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
 const act = (React as { act?: (cb: () => void | Promise<void>) => void | Promise<void> }).act as (cb: () => void | Promise<void>) => void | Promise<void>;
@@ -155,6 +156,7 @@ describe('InterfaceSettings', () => {
     });
 
     expect(testState.changeLanguageMock).toHaveBeenCalledWith('fr');
+    expect(localStorage.getItem(INTERFACE_LANGUAGE_STORAGE_KEY)).toBe('fr');
   });
 
   it('disables the update button while fetching and restores it afterward', async () => {
diff --git a/src/components/settings-modal/interface-settings/interface-settings.tsx b/src/components/settings-modal/interface-settings/interface-settings.tsx
index 43022e4d..d8c5393c 100644
--- a/src/components/settings-modal/interface-settings/interface-settings.tsx
+++ b/src/components/settings-modal/interface-settings/interface-settings.tsx
@@ -6,6 +6,7 @@ import capitalize from 'lodash/capitalize';
 import useExpandedMediaStore from '../../../stores/use-expanded-media-store';
 import useFeedViewSettingsStore from '../../../stores/use-feed-view-settings-store';
 import Version from '../../version';
+import { INTERFACE_LANGUAGE_STORAGE_KEY, SUPPORTED_INTERFACE_LANGUAGES } from '../../../lib/constants';
 
 const commitRef = process.env.VITE_COMMIT_REF;
 const isElectron = window.electronApi?.isElectron === true;
@@ -67,21 +68,20 @@ const CheckForUpdates = () => {
   );
 };
 
-// prettier-ignore
-const availableLanguages = ['ar', 'bn', 'cs', 'da', 'de', 'el', 'en', 'es', 'fa', 'fi', 'fil', 'fr', 'he', 'hi', 'hu', 'id', 'it', 'ja', 'ko', 'mr', 'nl', 'no', 'pl', 'pt', 'ro', 'ru', 'sq', 'sv', 'te', 'th', 'tr', 'uk', 'ur', 'vi', 'zh'];
-
 const InterfaceLanguage = () => {
   const { i18n } = useTranslation();
   const { changeLanguage, language } = i18n;
 
   const onSelectLanguage = (e: React.ChangeEvent<HTMLSelectElement>) => {
-    changeLanguage(e.target.value);
+    const selectedLanguage = e.target.value;
+    localStorage.setItem(INTERFACE_LANGUAGE_STORAGE_KEY, selectedLanguage);
+    changeLanguage(selectedLanguage);
   };
 
   return (
     <div className={styles.languageSettings}>
       <select value={language} onChange={onSelectLanguage}>
-        {availableLanguages.map((lang) => (
+        {SUPPORTED_INTERFACE_LANGUAGES.map((lang) => (
           <option key={lang} value={lang}>
             {lang}
           </option>
diff --git a/src/lib/__tests__/init-translations.test.ts b/src/lib/__tests__/init-translations.test.ts
index d55acdad..25e0cb45 100644
--- a/src/lib/__tests__/init-translations.test.ts
+++ b/src/lib/__tests__/init-translations.test.ts
@@ -1,4 +1,5 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { DEFAULT_INTERFACE_LANGUAGE, INTERFACE_LANGUAGE_STORAGE_KEY } from '../constants';
 
 const testState = vi.hoisted(() => {
   const i18next = {
@@ -47,10 +48,15 @@ describe('init-translations', () => {
     expect(testState.i18next.use).toHaveBeenNthCalledWith(3, testState.reactPlugin);
     expect(testState.i18next.init).toHaveBeenCalledWith(
       expect.objectContaining({
-        fallbackLng: 'en',
+        fallbackLng: DEFAULT_INTERFACE_LANGUAGE,
         ns: ['default'],
         defaultNS: 'default',
         backend: { loadPath: './translations/{{lng}}/{{ns}}.json' },
+        detection: {
+          order: ['localStorage'],
+          caches: ['localStorage'],
+          lookupLocalStorage: INTERFACE_LANGUAGE_STORAGE_KEY,
+        },
       }),
     );
     expect(testState.i18next.init.mock.calls[0]?.[0]?.supportedLngs).toContain('en');
diff --git a/src/lib/constants.ts b/src/lib/constants.ts
index a9316ae4..16a7868c 100644
--- a/src/lib/constants.ts
+++ b/src/lib/constants.ts
@@ -6,3 +6,47 @@ export const BOARD_REPLIES_PREVIEW_VISIBLE_COUNT = 5;
 
 /** Number of replies fetched for preview mode on board/listing views. */
 export const BOARD_REPLIES_PREVIEW_FETCH_SIZE = 25;
+
+/** 5chan ships in English by default; users must opt into other languages manually. */
+export const DEFAULT_INTERFACE_LANGUAGE = 'en';
+
+/** Persist only deliberate in-app language selections, never OS/browser auto-detection. */
+export const INTERFACE_LANGUAGE_STORAGE_KEY = '5chan-interface-language';
+
+export const SUPPORTED_INTERFACE_LANGUAGES = [
+  'ar',
+  'bn',
+  'cs',
+  'da',
+  'de',
+  'el',
+  'en',
+  'es',
+  'fa',
+  'fi',
+  'fil',
+  'fr',
+  'he',
+  'hi',
+  'hu',
+  'id',
+  'it',
+  'ja',
+  'ko',
+  'mr',
+  'nl',
+  'no',
+  'pl',
+  'pt',
+  'ro',
+  'ru',
+  'sq',
+  'sv',
+  'te',
+  'th',
+  'tr',
+  'uk',
+  'ur',
+  'vi',
+  'zh',
+] as const;
diff --git a/src/lib/init-translations.ts b/src/lib/init-translations.ts
index dacc105b..302f9d83 100644
--- a/src/lib/init-translations.ts
+++ b/src/lib/init-translations.ts
@@ -2,6 +2,7 @@ import i18next from 'i18next';
 import HttpBackend from 'i18next-http-backend';
 import LanguageDetector from 'i18next-browser-languagedetector';
 import { initReactI18next } from 'react-i18next';
+import { DEFAULT_INTERFACE_LANGUAGE, INTERFACE_LANGUAGE_STORAGE_KEY, SUPPORTED_INTERFACE_LANGUAGES } from './constants';
 
 const loadPath = `./translations/{{lng}}/{{ns}}.json`;
 
@@ -10,44 +11,13 @@ i18next
   .use(LanguageDetector)
   .use(initReactI18next)
   .init({
-    fallbackLng: 'en',
-    supportedLngs: [
-      'ar',
-      'bn',
-      'cs',
-      'da',
-      'de',
-      'el',
-      'en',
-      'es',
-      'fa',
-      'fi',
-      'fil',
-      'fr',
-      'he',
-      'hi',
-      'hu',
-      'id',
-      'it',
-      'ja',
-      'ko',
-      'mr',
-      'nl',
-      'no',
-      'pl',
-      'pt',
-      'ro',
-      'ru',
-      'sq',
-      'sv',
-      'te',
-      'th',
-      'tr',
-      'uk',
-      'ur',
-      'vi',
-      'zh',
-    ],
+    fallbackLng: DEFAULT_INTERFACE_LANGUAGE,
+    supportedLngs: [...SUPPORTED_INTERFACE_LANGUAGES],
+    detection: {
+      order: ['localStorage'],
+      caches: ['localStorage'],
+      lookupLocalStorage: INTERFACE_LANGUAGE_STORAGE_KEY,
+    },
 
     ns: ['default'],
     defaultNS: 'default',