fix(desktop): language switching + window drag hardening

apps/desktop/src/renderer/src/components/LanguageToggle.tsx

@@ -1,8 +1,11 @@
 import { setLocale as applyLocale, getCurrentLocale, useT } from '@open-codesign/i18n';
 import type { Locale } from '@open-codesign/i18n';
 import { Globe } from 'lucide-react';
+import type { CSSProperties } from 'react';
 import { useEffect, useState } from 'react';
 
+const noDragStyle = { WebkitAppRegion: 'no-drag' } as CSSProperties;
+
 function nextLocale(locale: Locale): Locale {
   return locale === 'en' ? 'zh-CN' : 'en';
 }
@@ -30,6 +33,7 @@ export function LanguageToggle() {
     <button
       type="button"
       onClick={() => void handleToggle()}
+      style={noDragStyle}
       className="inline-flex items-center gap-2 h-8 px-3 rounded-[var(--radius-md)] border border-[var(--color-border)] bg-[var(--color-surface)] text-[12px] text-[var(--color-text-primary)] hover:bg-[var(--color-surface-hover)] transition-colors"
       aria-label={t('settings.language.label')}
       title={t('settings.language.label')}

apps/desktop/src/renderer/src/components/Settings.tsx

@@ -1,3 +1,4 @@
+import { setLocale as applyLocale } from '@open-codesign/i18n';
 import type {
   OnboardingState,
   PROVIDER_SHORTLIST,
@@ -777,9 +778,10 @@ function AppearanceTab() {
 
   async function handleLocaleChange(v: string) {
     if (!window.codesign) return;
-    setLocale(v);
     try {
-      await window.codesign.locale.set(v);
+      const persisted = await window.codesign.locale.set(v);
+      const applied = await applyLocale(persisted);
+      setLocale(applied);
     } catch (err) {
       pushToast({
         variant: 'error',
@@ -829,7 +831,7 @@ function AppearanceTab() {
       </div>
 
       <div className="pt-2 border-t border-[var(--color-border-subtle)]">
-        <Row label="Language" hint="Restart the app after changing the language.">
+        <Row label="Language" hint="Language changes take effect immediately.">
           <NativeSelect
             value={locale}
             onChange={handleLocaleChange}

packages/i18n/src/i18n.test.ts

@@ -1,5 +1,12 @@
 import { describe, expect, it, vi } from 'vitest';
-import { availableLocales, initI18n, isSupportedLocale, normalizeLocale, setLocale } from './index';
+import {
+  availableLocales,
+  getCurrentLocale,
+  initI18n,
+  isSupportedLocale,
+  normalizeLocale,
+  setLocale,
+} from './index';
 
 describe('normalizeLocale', () => {
   it('returns the value unchanged when it is supported', () => {
@@ -69,4 +76,19 @@ describe('initI18n + setLocale (live switching)', () => {
     expect(warn).toHaveBeenCalled();
     warn.mockRestore();
   });
+
+  it('setLocale updates getCurrentLocale and i18n.t() immediately (no restart needed)', async () => {
+    const { i18n } = await import('./index');
+    await initI18n('en');
+    expect(getCurrentLocale()).toBe('en');
+    expect(i18n.t('common.send')).toBe('Send');
+
+    await setLocale('zh-CN');
+    expect(getCurrentLocale()).toBe('zh-CN');
+    expect(i18n.t('common.send')).toBe('发送');
+
+    await setLocale('en');
+    expect(getCurrentLocale()).toBe('en');
+    expect(i18n.t('common.send')).toBe('Send');
+  });
 });