feat(web): add quick language and theme switchers to user menu

- Add language and theme selector submenus to UserMenu component for quick access
- Refactor shared utilities: extract THEME_OPTIONS constant and getLocaleDisplayName() function
- Update LocaleSelect and ThemeSelect to use shared utilities, eliminating code duplication
- Make UserMenu reactive with MobX observer for real-time setting updates
- Fix language switching reactivity by immediately updating workspaceStore.state.locale
- Add scrollable menu support for language selector (max-h-[90vh])
- Apply same instant locale update to PreferencesSection for consistency

🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>

web/src/components/LocaleSelect.tsx

@@ -2,6 +2,7 @@ import { GlobeIcon } from "lucide-react";
 import { FC } from "react";
 import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
 import { locales } from "@/i18n";
+import { getLocaleDisplayName } from "@/utils/i18n";
 
 interface Props {
   value: Locale;
@@ -24,26 +25,11 @@ const LocaleSelect: FC<Props> = (props: Props) => {
         </div>
       </SelectTrigger>
       <SelectContent>
-        {locales.map((locale) => {
-          try {
-            const languageName = new Intl.DisplayNames([locale], { type: "language" }).of(locale);
-            if (languageName) {
-              return (
-                <SelectItem key={locale} value={locale}>
-                  {languageName.charAt(0).toUpperCase() + languageName.slice(1)}
-                </SelectItem>
-              );
-            }
-          } catch {
-            // do nth
-          }
-
-          return (
-            <SelectItem key={locale} value={locale}>
-              {locale}
-            </SelectItem>
-          );
-        })}
+        {locales.map((locale) => (
+          <SelectItem key={locale} value={locale}>
+            {getLocaleDisplayName(locale)}
+          </SelectItem>
+        ))}
       </SelectContent>
     </Select>
   );

web/src/components/Settings/PreferencesSection.tsx

 import { observer } from "mobx-react-lite";
 import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
 import { Separator } from "@/components/ui/separator";
-import { userStore } from "@/store";
+import { userStore, workspaceStore } from "@/store";
 import { Visibility } from "@/types/proto/api/v1/memo_service";
 import { UserSetting_GeneralSetting } from "@/types/proto/api/v1/user_service";
 import { useTranslate } from "@/utils/i18n";
@@ -16,6 +16,9 @@ const PreferencesSection = observer(() => {
   const generalSetting = userStore.state.userGeneralSetting;
 
   const handleLocaleSelectChange = async (locale: Locale) => {
+    // Update workspace store immediately for instant UI feedback
+    workspaceStore.state.setPartial({ locale });
+    // Persist to user settings
     await userStore.updateUserGeneralSetting({ locale }, ["locale"]);
   };
 

web/src/components/ThemeSelect.tsx

 import { Moon, Palette, Sun, Wallpaper } from "lucide-react";
 import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
 import { workspaceStore } from "@/store";
+import { THEME_OPTIONS } from "@/utils/theme";
 
 interface ThemeSelectProps {
   value?: string;
@@ -8,16 +9,16 @@ interface ThemeSelectProps {
   className?: string;
 }
 
+const THEME_ICONS: Record<string, JSX.Element> = {
+  default: <Sun className="w-4 h-4" />,
+  "default-dark": <Moon className="w-4 h-4" />,
+  paper: <Palette className="w-4 h-4" />,
+  whitewall: <Wallpaper className="w-4 h-4" />,
+};
+
 const ThemeSelect = ({ value, onValueChange, className }: ThemeSelectProps = {}) => {
   const currentTheme = value || workspaceStore.state.theme || "default";
 
-  const themeOptions: { value: Theme; icon: JSX.Element; label: string }[] = [
-    { value: "default", icon: <Sun className="w-4 h-4" />, label: "Default Light" },
-    { value: "default-dark", icon: <Moon className="w-4 h-4" />, label: "Default Dark" },
-    { value: "paper", icon: <Palette className="w-4 h-4" />, label: "Paper" },
-    { value: "whitewall", icon: <Wallpaper className="w-4 h-4" />, label: "Whitewall" },
-  ];
-
   const handleThemeChange = (newTheme: Theme) => {
     if (onValueChange) {
       onValueChange(newTheme);
@@ -34,10 +35,10 @@ const ThemeSelect = ({ value, onValueChange, className }: ThemeSelectProps = {})
         </div>
       </SelectTrigger>
       <SelectContent>
-        {themeOptions.map((option) => (
+        {THEME_OPTIONS.map((option) => (
           <SelectItem key={option.value} value={option.value}>
             <div className="flex items-center gap-2">
-              {option.icon}
+              {THEME_ICONS[option.value]}
               <span>{option.label}</span>
             </div>
           </SelectItem>

web/src/components/UserMenu.tsx

-import { ArchiveIcon, LogOutIcon, User2Icon, SquareUserIcon, SettingsIcon, BellIcon } from "lucide-react";
+import {
+  ArchiveIcon,
+  LogOutIcon,
+  User2Icon,
+  SquareUserIcon,
+  SettingsIcon,
+  BellIcon,
+  GlobeIcon,
+  PaletteIcon,
+  CheckIcon,
+} from "lucide-react";
+import { observer } from "mobx-react-lite";
 import { authServiceClient } from "@/grpcweb";
 import useCurrentUser from "@/hooks/useCurrentUser";
 import useNavigateTo from "@/hooks/useNavigateTo";
+import { locales } from "@/i18n";
 import { cn } from "@/lib/utils";
 import { Routes } from "@/router";
-import { useTranslate } from "@/utils/i18n";
+import { userStore, workspaceStore } from "@/store";
+import { getLocaleDisplayName, useTranslate } from "@/utils/i18n";
+import { THEME_OPTIONS } from "@/utils/theme";
 import UserAvatar from "./UserAvatar";
-import { DropdownMenu, DropdownMenuContent, DropdownMenuItem, DropdownMenuTrigger } from "./ui/dropdown-menu";
+import {
+  DropdownMenu,
+  DropdownMenuContent,
+  DropdownMenuItem,
+  DropdownMenuSub,
+  DropdownMenuSubContent,
+  DropdownMenuSubTrigger,
+  DropdownMenuTrigger,
+} from "./ui/dropdown-menu";
 
 interface Props {
   collapsed?: boolean;
 }
 
-const UserMenu = (props: Props) => {
+const UserMenu = observer((props: Props) => {
   const { collapsed } = props;
   const t = useTranslate();
   const navigateTo = useNavigateTo();
   const currentUser = useCurrentUser();
+  const generalSetting = userStore.state.userGeneralSetting;
+  const currentLocale = generalSetting?.locale || "en";
+  const currentTheme = generalSetting?.theme || "default";
+
+  const handleLocaleChange = async (locale: Locale) => {
+    // Update workspace store immediately for instant UI feedback
+    workspaceStore.state.setPartial({ locale });
+    // Persist to user settings
+    await userStore.updateUserGeneralSetting({ locale }, ["locale"]);
+  };
+
+  const handleThemeChange = async (theme: string) => {
+    await userStore.updateUserGeneralSetting({ theme }, ["theme"]);
+  };
 
   const handleSignOut = async () => {
     await authServiceClient.deleteSession({});
@@ -67,6 +103,36 @@ const UserMenu = (props: Props) => {
           <BellIcon className="size-4 text-muted-foreground" />
           {t("common.inbox")}
         </DropdownMenuItem>
+        <DropdownMenuSub>
+          <DropdownMenuSubTrigger>
+            <GlobeIcon className="size-4 text-muted-foreground" />
+            {t("common.language")}
+          </DropdownMenuSubTrigger>
+          <DropdownMenuSubContent className="max-h-[90vh] overflow-y-auto">
+            {locales.map((locale) => (
+              <DropdownMenuItem key={locale} onClick={() => handleLocaleChange(locale)}>
+                {currentLocale === locale && <CheckIcon className="w-4 h-auto mr-2" />}
+                {currentLocale !== locale && <span className="w-4 mr-2" />}
+                {getLocaleDisplayName(locale)}
+              </DropdownMenuItem>
+            ))}
+          </DropdownMenuSubContent>
+        </DropdownMenuSub>
+        <DropdownMenuSub>
+          <DropdownMenuSubTrigger>
+            <PaletteIcon className="size-4 text-muted-foreground" />
+            {t("setting.preference-section.theme")}
+          </DropdownMenuSubTrigger>
+          <DropdownMenuSubContent>
+            {THEME_OPTIONS.map((option) => (
+              <DropdownMenuItem key={option.value} onClick={() => handleThemeChange(option.value)}>
+                {currentTheme === option.value && <CheckIcon className="w-4 h-auto mr-2" />}
+                {currentTheme !== option.value && <span className="w-4 mr-2" />}
+                {option.label}
+              </DropdownMenuItem>
+            ))}
+          </DropdownMenuSubContent>
+        </DropdownMenuSub>
         <DropdownMenuItem onClick={() => navigateTo(Routes.SETTING)}>
           <SettingsIcon className="size-4 text-muted-foreground" />
           {t("common.settings")}
@@ -78,6 +144,6 @@ const UserMenu = (props: Props) => {
       </DropdownMenuContent>
     </DropdownMenu>
   );
-};
+});
 
 export default UserMenu;

web/src/utils/i18n.ts

@@ -51,3 +51,20 @@ export const isValidateLocale = (locale: string | undefined | null): boolean =>
   if (!locale) return false;
   return locales.includes(locale);
 };
+
+/**
+ * Get the display name for a locale in its native language
+ * @param locale - The locale code (e.g., "en", "zh-Hans", "fr")
+ * @returns The display name with capitalized first letter, or the locale code if display name is unavailable
+ */
+export const getLocaleDisplayName = (locale: string): string => {
+  try {
+    const displayName = new Intl.DisplayNames([locale], { type: "language" }).of(locale);
+    if (displayName) {
+      return displayName.charAt(0).toUpperCase() + displayName.slice(1);
+    }
+  } catch {
+    // Intl.DisplayNames might not be available or might fail for some locales
+  }
+  return locale;
+};

web/src/utils/theme.ts

@@ -12,6 +12,18 @@ const THEME_CONTENT: Record<ValidTheme, string | null> = {
   whitewall: whitewallThemeContent,
 };
 
+export interface ThemeOption {
+  value: string;
+  label: string;
+}
+
+export const THEME_OPTIONS: ThemeOption[] = [
+  { value: "default", label: "Default Light" },
+  { value: "default-dark", label: "Default Dark" },
+  { value: "paper", label: "Paper" },
+  { value: "whitewall", label: "Whitewall" },
+];
+
 const validateTheme = (theme: string): ValidTheme => {
   return VALID_THEMES.includes(theme as ValidTheme) ? (theme as ValidTheme) : "default";
 };