chore: translations were still missing

tests/renderer/i18n.test.ts

@@ -1,10 +1,25 @@
 import { describe, expect, it } from 'vitest';
+import React from 'react';
+import { render, screen } from '@testing-library/react';
 import {
+  I18nProvider,
+  UI_LANGUAGE_STORAGE_KEY,
+  useI18n,
   translateUi,
   resolveSupportedUiLanguage,
   resolveUiLanguageFromSystemLocale,
 } from '../../src/renderer/i18n';
 
+const LanguageProbe: React.FC = () => {
+  const { language, t } = useI18n();
+  return React.createElement(
+    React.Fragment,
+    null,
+    React.createElement('span', { 'data-testid': 'language' }, language),
+    React.createElement('span', { 'data-testid': 'save-label' }, t('common.save')),
+  );
+};
+
 describe('renderer i18n', () => {
   it('resolves supported ui language from OS locale', () => {
     expect(resolveUiLanguageFromSystemLocale('de-DE')).toBe('de');
@@ -24,4 +39,24 @@ describe('renderer i18n', () => {
     expect(translateUi('de', 'settings.language.english')).toBe('Englisch');
     expect(translateUi('it', 'missing.key')).toBe('missing.key');
   });
+
+  it('uses system locale for ui language when no persisted choice exists', async () => {
+    localStorage.removeItem(UI_LANGUAGE_STORAGE_KEY);
+    (window.electronAPI.app as { getSystemLanguage?: () => Promise<string> }).getSystemLanguage = async () => 'de-DE';
+
+    render(React.createElement(I18nProvider, null, React.createElement(LanguageProbe)));
+
+    expect(await screen.findByTestId('language')).toHaveTextContent('de');
+    expect(screen.getByTestId('save-label')).toHaveTextContent('Speichern');
+  });
+
+  it('uses persisted ui language over system locale', async () => {
+    localStorage.setItem(UI_LANGUAGE_STORAGE_KEY, 'fr');
+    (window.electronAPI.app as { getSystemLanguage?: () => Promise<string> }).getSystemLanguage = async () => 'de-DE';
+
+    render(React.createElement(I18nProvider, null, React.createElement(LanguageProbe)));
+
+    expect(await screen.findByTestId('language')).toHaveTextContent('fr');
+    expect(screen.getByTestId('save-label')).toHaveTextContent('Enregistrer');
+  });
 });