feat(desktop): gate traffic-lights behind window-controls style setting

packages/ui/src/components/desktop/WindowsWindowControls.tsx

@@ -5,6 +5,80 @@ import { useI18n } from '@/lib/i18n';
 import { cn } from '@/lib/utils';
 import { getDesktopWindowControlsOrder, invokeDesktop } from '@/lib/desktop';
 import type { DesktopWindowControlAction, DesktopWindowControlsSide } from '@/lib/desktop';
+import { useUIStore } from '@/stores/useUIStore';
+
+// macOS chrome colors; intentionally theme-independent — these replicate a
+// foreign platform's chrome, not OpenChamber's own status tokens, so the
+// theme-system hex rule does not apply.
+const TRAFFIC_LIGHT_COLORS: Record<DesktopWindowControlAction, { fill: string; glyph: string }> = {
+  close: { fill: '#FF5F57', glyph: '#7F0808' },
+  minimize: { fill: '#FEBC2E', glyph: '#B3710C' },
+  maximize: { fill: '#28C940', glyph: '#006200' },
+};
+
+const TrafficLightGlyph: React.FC<{ action: DesktopWindowControlAction }> = ({ action }) => {
+  if (action === 'close') {
+    return (
+      <svg viewBox="0 0 12 12" fill="none" stroke="currentColor" strokeWidth={1.2} strokeLinecap="round" className="size-[9px]" aria-hidden>
+        <path d="M3.5 3.5 L8.5 8.5 M8.5 3.5 L3.5 8.5" />
+      </svg>
+    );
+  }
+  if (action === 'minimize') {
+    return (
+      <svg viewBox="0 0 12 12" fill="none" stroke="currentColor" strokeWidth={1.4} strokeLinecap="round" className="size-[9px]" aria-hidden>
+        <path d="M3 6 L9 6" />
+      </svg>
+    );
+  }
+  // Green expand: two paired corner triangles pointing diagonally outward.
+  return (
+    <svg viewBox="0 0 12 12" fill="currentColor" className="size-[9px]" aria-hidden>
+      <path d="M5.25 2.25 L9.75 2.25 L9.75 6.75 Z" />
+      <path d="M6.75 9.75 L2.25 9.75 L2.25 5.25 Z" />
+    </svg>
+  );
+};
+
+type TrafficLightButtonProps = {
+  action: DesktopWindowControlAction;
+  isMaximized: boolean;
+  onActivate: (action: DesktopWindowControlAction) => void;
+};
+
+const TrafficLightButton: React.FC<TrafficLightButtonProps> = ({ action, isMaximized, onActivate }) => {
+  const { t } = useI18n();
+  const { fill, glyph } = TRAFFIC_LIGHT_COLORS[action];
+  const label =
+    action === 'close'
+      ? t('header.windowControls.close')
+      : action === 'minimize'
+        ? t('header.windowControls.minimize')
+        : isMaximized
+          ? t('header.windowControls.restore')
+          : t('header.windowControls.maximize');
+  return (
+    <button
+      type="button"
+      onClick={() => onActivate(action)}
+      title={label}
+      aria-label={label}
+      // 24px-wide button wrapping a 14px circle centers it at a 24px interval
+      // between neighbors, giving a 10px edge-to-edge gap. The 32px height
+      // keeps the titlebar's vertical hit band.
+      className="app-region-no-drag flex h-8 w-[24px] items-center justify-center rounded-md focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-primary"
+    >
+      <span
+        className="flex size-3.5 items-center justify-center rounded-full shadow-[inset_0_0_0_0.5px_rgba(0,0,0,0.28)] transition-[filter] duration-75 active:brightness-90"
+        style={{ backgroundColor: fill, color: glyph }}
+      >
+        <span className="flex opacity-0 transition-opacity duration-75 group-hover/wctl:opacity-100">
+          <TrafficLightGlyph action={action} />
+        </span>
+      </span>
+    </button>
+  );
+};
 
 type WindowsWindowControlsProps = {
   visible: boolean;
@@ -17,6 +91,7 @@ export const WindowsWindowControls = React.memo(function WindowsWindowControls({
 }: WindowsWindowControlsProps) {
   const { t } = useI18n();
   const [isMaximized, setIsMaximized] = React.useState(false);
+  const desktopWindowControlsStyle = useUIStore((state) => state.desktopWindowControlsStyle);
 
   useEffect(() => {
     if (!visible) {
@@ -48,12 +123,50 @@ export const WindowsWindowControls = React.memo(function WindowsWindowControls({
     return null;
   }
 
-  // Left-side controls sit in the same cluster as h-8 titlebar icon buttons
-  // (app menu / sidebar / project actions). Match that size and avoid negative
-  // margins so TitlebarLeftControls can publish an accurate reserved width —
-  // otherwise the project-actions chevron overlaps the session title.
-  // Right-side controls keep a taller Windows-style hit target.
   const isLeft = position === 'left';
+  // Order is side-driven for both styles: close, minimize, maximize on the
+  // left; minimize, maximize, close on the right.
+  const order = getDesktopWindowControlsOrder(position);
+
+  const activate = (action: DesktopWindowControlAction) => {
+    if (action === 'close') {
+      void invokeDesktop('desktop_close_current_window');
+      return;
+    }
+    if (action === 'minimize') {
+      void invokeDesktop('desktop_minimize_current_window');
+      return;
+    }
+    void invokeDesktop<{ maximized?: boolean }>('desktop_toggle_current_window_maximized')
+      .then((state) => setIsMaximized(Boolean(state?.maximized)))
+      .catch(() => {});
+  };
+
+  // Traffic-light chrome: macOS-style 14px circles in an h-8 band. Glyphs
+  // reveal on any-cluster hover (group-hover/wctl). TitlebarLeftControls
+  // measures and republishes the cluster width via ResizeObserver, so the
+  // narrower footprint takes effect without touching reserved-width constants.
+  if (desktopWindowControlsStyle === 'traffic-lights') {
+    return (
+      <div
+        className={cn(
+          'app-region-no-drag group/wctl flex h-8 shrink-0 items-center',
+          isLeft ? 'mr-1' : 'ml-1',
+        )}
+        aria-label={t('header.windowControls.groupAria')}
+      >
+        {order.map((action) => (
+          <TrafficLightButton key={action} action={action} isMaximized={isMaximized} onActivate={activate} />
+        ))}
+      </div>
+    );
+  }
+
+  // Classic Windows-style square buttons. Left side matches the h-8 titlebar
+  // icon cluster (app menu / sidebar / project actions) and avoids negative
+  // margins so TitlebarLeftControls publishes an accurate reserved width —
+  // otherwise the project-actions chevron overlaps the session title. Right
+  // side keeps a taller h-12 Windows-style hit target.
   const buttonClassName = cn(
     'app-region-no-drag inline-flex items-center justify-center text-muted-foreground transition-colors hover:bg-interactive-hover hover:text-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-primary',
     isLeft ? 'h-8 w-8 rounded-md' : 'h-12 w-11',
@@ -113,7 +226,7 @@ export const WindowsWindowControls = React.memo(function WindowsWindowControls({
 
   return (
     <div className={containerClassName} aria-label={t('header.windowControls.groupAria')}>
-      {getDesktopWindowControlsOrder(position).map(renderControl)}
+      {order.map(renderControl)}
     </div>
   );
 });

packages/ui/src/components/sections/openchamber/OpenChamberVisualSettings.tsx

@@ -24,6 +24,7 @@ import {
     isWebRuntime,
     usesFramelessElectronChrome,
     type DesktopWindowControlsPosition,
+    type DesktopWindowControlsStyle,
 } from '@/lib/desktop';
 import { useDeviceInfo } from '@/lib/device';
 import { usePwaDetection } from '@/hooks/usePwaDetection';
@@ -285,6 +286,11 @@ const WINDOW_CONTROLS_POSITION_OPTIONS: Array<{ id: DesktopWindowControlsPositio
     { id: 'right', labelKey: 'settings.openchamber.desktopNetwork.option.windowControlsRight' },
 ];
 
+const WINDOW_CONTROLS_STYLE_OPTIONS: Array<{ id: DesktopWindowControlsStyle; labelKey: string }> = [
+    { id: 'classic', labelKey: 'settings.openchamber.desktopNetwork.option.windowControlsClassic' },
+    { id: 'traffic-lights', labelKey: 'settings.openchamber.desktopNetwork.option.windowControlsTrafficLights' },
+];
+
 interface OpenChamberVisualSettingsProps {
     /** Which settings to show. If undefined, shows all. */
     visibleSettings?: VisibleSetting[];
@@ -425,6 +431,8 @@ export const OpenChamberVisualSettings: React.FC<OpenChamberVisualSettingsProps>
     const showWindowControlsPosition = usesFramelessElectronChrome();
     const desktopWindowControlsPosition = useUIStore((state) => state.desktopWindowControlsPosition);
     const setDesktopWindowControlsPosition = useUIStore((state) => state.setDesktopWindowControlsPosition);
+    const desktopWindowControlsStyle = useUIStore((state) => state.desktopWindowControlsStyle);
+    const setDesktopWindowControlsStyle = useUIStore((state) => state.setDesktopWindowControlsStyle);
     const [chatRenderPreviewTick, setChatRenderPreviewTick] = React.useState(0);
     const reportUsage = useUIStore(state => state.reportUsage);
     const setReportUsage = useUIStore(state => state.setReportUsage);
@@ -440,6 +448,11 @@ export const OpenChamberVisualSettings: React.FC<OpenChamberVisualSettingsProps>
         void updateDesktopSettings({ desktopWindowControlsPosition: value });
     }, [setDesktopWindowControlsPosition]);
 
+    const handleWindowControlsStyleChange = React.useCallback((value: DesktopWindowControlsStyle) => {
+        setDesktopWindowControlsStyle(value);
+        void updateDesktopSettings({ desktopWindowControlsStyle: value });
+    }, [setDesktopWindowControlsStyle]);
+
     const shouldAnimateChatPreview = (isSettingsDialogOpen || isMobile || isVSCodeRuntime())
         && (visibleSettings ? visibleSettings.includes('chatRenderMode') : true);
 
@@ -738,6 +751,10 @@ export const OpenChamberVisualSettings: React.FC<OpenChamberVisualSettingsProps>
         const option = MOBILE_KEYBOARD_MODE_OPTIONS.find((item) => item.id === mobileKeyboardMode);
         return option ? tUnsafe(option.labelKey) : undefined;
     }, [mobileKeyboardMode, tUnsafe]);
+    const selectedWindowControlsStyleLabel = React.useMemo(() => {
+        const option = WINDOW_CONTROLS_STYLE_OPTIONS.find((item) => item.id === desktopWindowControlsStyle);
+        return option ? tUnsafe(option.labelKey) : undefined;
+    }, [desktopWindowControlsStyle, tUnsafe]);
 
     const handleMobileLayoutPreferenceChange = React.useCallback((value: MobileLayoutPreference) => {
         if (value === mobileLayoutPreference) {
@@ -1010,20 +1027,41 @@ export const OpenChamberVisualSettings: React.FC<OpenChamberVisualSettingsProps>
 
                         {showWindowControlsPositionSetting && (
                             <SettingsSection
-                                title={t('settings.openchamber.desktopNetwork.field.windowControlsPosition')}
-                                description={t('settings.openchamber.desktopNetwork.field.windowControlsPositionDescription')}
+                                title={t('settings.openchamber.desktopNetwork.field.windowControls')}
+                                info={t('settings.openchamber.desktopNetwork.field.windowControlsDescription')}
                                 divider={hasThemeSettings}
-                                settingsItem="sessions.desktop-window-controls-position"
                             >
-                                <SettingsChipGroup
-                                    value={desktopWindowControlsPosition}
-                                    options={WINDOW_CONTROLS_POSITION_OPTIONS.map((option) => ({
-                                        value: option.id,
-                                        label: tUnsafe(option.labelKey),
-                                    }))}
-                                    onChange={handleWindowControlsPositionChange}
-                                    aria-label={t('settings.openchamber.desktopNetwork.field.windowControlsPositionAria')}
-                                />
+                                <SettingsTwoColumn>
+                                    <SettingsStackedField
+                                        label={t('settings.openchamber.desktopNetwork.field.windowControlsPosition')}
+                                        settingsItem="sessions.desktop-window-controls-position"
+                                    >
+                                        <SettingsChipGroup
+                                            value={desktopWindowControlsPosition}
+                                            options={WINDOW_CONTROLS_POSITION_OPTIONS.map((option) => ({
+                                                value: option.id,
+                                                label: tUnsafe(option.labelKey),
+                                            }))}
+                                            onChange={handleWindowControlsPositionChange}
+                                            aria-label={t('settings.openchamber.desktopNetwork.field.windowControlsPositionAria')}
+                                        />
+                                    </SettingsStackedField>
+                                    <SettingsStackedField
+                                        label={t('settings.openchamber.desktopNetwork.field.windowControlsStyle')}
+                                        settingsItem="sessions.desktop-window-controls-style"
+                                    >
+                                        <Select value={desktopWindowControlsStyle} onValueChange={(value: DesktopWindowControlsStyle) => handleWindowControlsStyleChange(value)}>
+                                            <SelectTrigger aria-label={t('settings.openchamber.desktopNetwork.field.windowControlsStyleAria')} size={SETTINGS_SELECT_SIZE} className={SETTINGS_SELECT_TRIGGER_CLASS}>
+                                                <SelectValue>{selectedWindowControlsStyleLabel}</SelectValue>
+                                            </SelectTrigger>
+                                            <SelectContent>
+                                                {WINDOW_CONTROLS_STYLE_OPTIONS.map((option) => (
+                                                    <SelectItem key={option.id} value={option.id}>{tUnsafe(option.labelKey)}</SelectItem>
+                                                ))}
+                                            </SelectContent>
+                                        </Select>
+                                    </SettingsStackedField>
+                                </SettingsTwoColumn>
                             </SettingsSection>
                         )}
 

packages/ui/src/index.css

@@ -71,6 +71,17 @@ html[data-oc-vibrancy] .main-content-safe-area {
   background-color: transparent !important;
 }
 
+/* ── Linux frameless window border ────────────────────────────────────────
+   `data-oc-window-border` is set on <html> by initLinuxWindowBorder()
+   (ui/src/lib/desktop.ts), and `data-oc-window-maximized` drops the border
+   so a maximized window stays flush with screen edges. Rounded corners
+   were removed: Electron 41's transparent-window path on Linux is unreliable
+   without --disable-gpu, and native rounded corners landed upstream only in
+   Electron 43 (PR #51459). */
+html[data-oc-window-border]:not([data-oc-window-maximized]) #root {
+  border: 1px solid var(--border);
+}
+
 /* Left sidebar: solid until the native layer is ready, then a translucent
    overlay so the vibrancy frosts through. */
 html[data-oc-vibrancy] .oc-vibrancy-surface {

packages/ui/src/lib/desktop.ts

@@ -41,6 +41,7 @@ export type SkillCatalogConfig = {
 export type DesktopWindowControlsPosition = 'left' | 'right';
 export type DesktopWindowControlsSide = 'left' | 'right';
 export type DesktopWindowControlAction = 'close' | 'minimize' | 'maximize';
+export type DesktopWindowControlsStyle = 'classic' | 'traffic-lights';
 
 export type DesktopSettings = {
   themeId?: string;
@@ -142,6 +143,7 @@ export type DesktopSettings = {
   pwaOrientation?: 'system' | 'portrait' | 'landscape';
   mobileKeyboardMode?: MobileKeyboardMode;
   desktopWindowControlsPosition?: DesktopWindowControlsPosition;
+  desktopWindowControlsStyle?: DesktopWindowControlsStyle;
   inputSpellcheckEnabled?: boolean;
   showOpenCodeUpdateNotifications?: boolean;
   agentControlToolEnabled?: boolean;
@@ -252,9 +254,6 @@ export const getElectronPlatform = (): string | null => {
   return typeof platform === 'string' ? platform : null;
 };
 
-/** Width of the three in-app window control buttons when placed on the left (3 × w-8). */
-export const DESKTOP_WINDOW_CONTROLS_WIDTH_PX = 96;
-
 /** Default side for in-app window controls (Windows-style, right). */
 export const DEFAULT_DESKTOP_WINDOW_CONTROLS_POSITION: DesktopWindowControlsPosition = 'right';
 
@@ -301,6 +300,37 @@ export const hasDesktopInvoke = (): boolean => {
   return typeof getDesktopBridge()?.invoke === 'function';
 };
 
+/**
+ * Linux frameless Electron windows show a 1px CSS border on #root (see
+ * index.css). This function flips the attribute on <html> so the rule
+ * matches, and tracks `data-oc-window-maximized` so the border drops when
+ * maximized (a 1px line inset from every screen edge would look off).
+ * No-op outside Linux frameless Electron.
+ */
+export const initLinuxWindowBorder = (): void => {
+  if (typeof window === 'undefined' || typeof document === 'undefined') return;
+  if (!usesFramelessElectronChrome()) return;
+  const platform = getElectronPlatform();
+  if (platform !== 'linux') return;
+
+  const root = document.documentElement;
+  root.setAttribute('data-oc-window-border', '');
+
+  const applyMaximized = (maximized: boolean) => {
+    root.toggleAttribute('data-oc-window-maximized', maximized);
+  };
+
+  void invokeDesktop<{ maximized?: boolean }>('desktop_get_current_window_state')
+    .then((state) => applyMaximized(Boolean(state?.maximized)))
+    .catch(() => {});
+
+  const onMaximizedChange = (event: Event) => {
+    const detail = (event as CustomEvent<{ maximized?: boolean }>).detail;
+    applyMaximized(Boolean(detail?.maximized));
+  };
+  window.addEventListener('openchamber:window-maximized-changed', onMaximizedChange);
+};
+
 export const canUseElectronDesktopIPC = (): boolean => isElectronShell() && hasDesktopInvoke();
 
 export const invokeDesktop = async <T = unknown>(command: string, args?: Record<string, unknown>): Promise<T | null> => {

packages/ui/src/lib/desktopWindowControls.test.ts

@@ -6,6 +6,7 @@ import {
   normalizeDesktopWindowControlsPosition,
   resolveDesktopWindowControlsSide,
 } from './desktop';
+import { useUIStore } from '@/stores/useUIStore';
 
 describe('desktop window controls position', () => {
   test('defaults to right', () => {
@@ -30,3 +31,24 @@ describe('desktop window controls position', () => {
     expect(getDesktopWindowControlsOrder('right')).toEqual(['minimize', 'maximize', 'close']);
   });
 });
+
+describe('useUIStore v12→v13 migration', () => {
+  test('introduces classic style while preserving position', () => {
+    const migrate = useUIStore.persist.getOptions().migrate!;
+    const result = migrate({ desktopWindowControlsPosition: 'left' }, 12) as Record<string, unknown>;
+    expect(result.desktopWindowControlsPosition).toBe('left');
+    expect(result.desktopWindowControlsStyle).toBe('classic');
+  });
+
+  test('does not overwrite a persisted style', () => {
+    const migrate = useUIStore.persist.getOptions().migrate!;
+    const result = migrate({ desktopWindowControlsStyle: 'traffic-lights' }, 12) as Record<string, unknown>;
+    expect(result.desktopWindowControlsStyle).toBe('traffic-lights');
+  });
+
+  test('coerces an invalid persisted style to classic', () => {
+    const migrate = useUIStore.persist.getOptions().migrate!;
+    const result = migrate({ desktopWindowControlsStyle: 'macos' }, 12) as Record<string, unknown>;
+    expect(result.desktopWindowControlsStyle).toBe('classic');
+  });
+});

packages/ui/src/lib/i18n/messages/en.settings.ts

@@ -945,11 +945,16 @@ export const settingsDict = {
   'settings.openchamber.sessionRetention.toast.failedArchiveCount': 'Failed to archive {count} session(s)',
   'settings.openchamber.sessionRetention.toast.failedDeleteCount': 'Failed to delete {count} session(s)',
   'settings.openchamber.desktopNetwork.title': 'Desktop Network Access',
-  'settings.openchamber.desktopNetwork.field.windowControlsPosition': 'Window controls position',
-  'settings.openchamber.desktopNetwork.field.windowControlsPositionDescription': 'Choose where minimize, maximize, and close buttons appear. Defaults to the right.',
+  'settings.openchamber.desktopNetwork.field.windowControls': 'Window controls',
+  'settings.openchamber.desktopNetwork.field.windowControlsDescription': 'Choose where window controls appear and how they look.',
+  'settings.openchamber.desktopNetwork.field.windowControlsPosition': 'Position',
   'settings.openchamber.desktopNetwork.field.windowControlsPositionAria': 'Window controls position',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyle': 'Style',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyleAria': 'Window controls style',
   'settings.openchamber.desktopNetwork.option.windowControlsLeft': 'Left',
   'settings.openchamber.desktopNetwork.option.windowControlsRight': 'Right',
+  'settings.openchamber.desktopNetwork.option.windowControlsClassic': 'Classic',
+  'settings.openchamber.desktopNetwork.option.windowControlsTrafficLights': 'Traffic lights',
   'settings.openchamber.desktopNetwork.field.launchAtLoginAria': 'Start OpenChamber at login',
   'settings.openchamber.desktopNetwork.field.launchAtLogin': 'Start OpenChamber when you log in',
   'settings.openchamber.desktopNetwork.field.launchAtLoginDescription': 'Starts the app in the background without opening a window. Use the desktop status icon to open it.',

packages/ui/src/lib/i18n/messages/es.settings.ts

@@ -912,11 +912,16 @@ export const settingsDict = {
   "settings.openchamber.sessionRetention.toast.failedArchiveCount": "No se pudo archivar {count} sesión(es)",
   "settings.openchamber.sessionRetention.toast.failedDeleteCount": "No se pudo eliminar {count} sesión(es)",
   "settings.openchamber.desktopNetwork.title": "Acceso de red de escritorio",
-  "settings.openchamber.desktopNetwork.field.windowControlsPosition": "Posición de los controles de ventana",
-  "settings.openchamber.desktopNetwork.field.windowControlsPositionDescription": "Elige dónde aparecen los botones de minimizar, maximizar y cerrar. Por defecto a la derecha.",
+  "settings.openchamber.desktopNetwork.field.windowControls": "Controles de ventana",
+  "settings.openchamber.desktopNetwork.field.windowControlsDescription": "Elige dónde aparecen los controles de ventana y su apariencia.",
+  "settings.openchamber.desktopNetwork.field.windowControlsPosition": "Posición",
   "settings.openchamber.desktopNetwork.field.windowControlsPositionAria": "Posición de los controles de ventana",
+  "settings.openchamber.desktopNetwork.field.windowControlsStyle": "Estilo",
+  "settings.openchamber.desktopNetwork.field.windowControlsStyleAria": "Estilo de los controles de ventana",
   "settings.openchamber.desktopNetwork.option.windowControlsLeft": "Izquierda",
   "settings.openchamber.desktopNetwork.option.windowControlsRight": "Derecha",
+  "settings.openchamber.desktopNetwork.option.windowControlsClassic": "Clásico",
+  "settings.openchamber.desktopNetwork.option.windowControlsTrafficLights": "Semáforo",
   "settings.openchamber.desktopNetwork.field.launchAtLoginAria": "Iniciar OpenChamber al iniciar sesión",
   "settings.openchamber.desktopNetwork.field.launchAtLogin": "Iniciar OpenChamber al iniciar sesión",
   "settings.openchamber.desktopNetwork.field.launchAtLoginDescription": "Inicia la app en segundo plano sin abrir una ventana. Usa el icono de estado del escritorio para abrirla.",

packages/ui/src/lib/i18n/messages/fr.settings.ts

@@ -833,11 +833,16 @@ export const settingsDict = {
   'settings.openchamber.sessionRetention.toast.failedArchiveCount': 'Échec de l\'archivage des sessions {count}',
   'settings.openchamber.sessionRetention.toast.failedDeleteCount': 'Échec de la suppression des sessions {count}',
   'settings.openchamber.desktopNetwork.title': 'Accès au réseau de bureau',
-  'settings.openchamber.desktopNetwork.field.windowControlsPosition': 'Position des contrôles de fenêtre',
-  'settings.openchamber.desktopNetwork.field.windowControlsPositionDescription': 'Choisissez où apparaissent les boutons Réduire, Agrandir et Fermer. Par défaut à droite.',
+  'settings.openchamber.desktopNetwork.field.windowControls': 'Contrôles de fenêtre',
+  'settings.openchamber.desktopNetwork.field.windowControlsDescription': 'Choisissez où apparaissent les contrôles de fenêtre et leur apparence.',
+  'settings.openchamber.desktopNetwork.field.windowControlsPosition': 'Position',
   'settings.openchamber.desktopNetwork.field.windowControlsPositionAria': 'Position des contrôles de fenêtre',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyle': 'Style',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyleAria': 'Style des contrôles de fenêtre',
   'settings.openchamber.desktopNetwork.option.windowControlsLeft': 'Gauche',
   'settings.openchamber.desktopNetwork.option.windowControlsRight': 'Droite',
+  'settings.openchamber.desktopNetwork.option.windowControlsClassic': 'Classique',
+  'settings.openchamber.desktopNetwork.option.windowControlsTrafficLights': 'Feux de circulation',
   'settings.openchamber.desktopNetwork.field.launchAtLoginAria': 'Démarrez OpenChamber lors de la connexion',
   'settings.openchamber.desktopNetwork.field.launchAtLogin': 'Démarrez OpenChamber lorsque vous vous connectez',
   'settings.openchamber.desktopNetwork.field.launchAtLoginDescription': 'Démarre l\'application en arrière-plan sans ouvrir de fenêtre. Utilisez l\'icône d\'état du bureau pour l\'ouvrir.',

packages/ui/src/lib/i18n/messages/ja.settings.ts

@@ -945,11 +945,16 @@ export const settingsDict = {
   'settings.openchamber.sessionRetention.toast.failedArchiveCount': '{count} 個の Session のアーカイブに失敗しました',
   'settings.openchamber.sessionRetention.toast.failedDeleteCount': '{count} 個の Session の削除に失敗しました',
   'settings.openchamber.desktopNetwork.title': 'Desktop ネットワークアクセス',
-  'settings.openchamber.desktopNetwork.field.windowControlsPosition': 'ウィンドウコントロールの位置',
-  'settings.openchamber.desktopNetwork.field.windowControlsPositionDescription': '最小化・最大化・閉じるボタンの表示位置を選びます。デフォルトは右側です。',
+  'settings.openchamber.desktopNetwork.field.windowControls': 'ウィンドウコントロール',
+  'settings.openchamber.desktopNetwork.field.windowControlsDescription': 'ウィンドウコントロールの表示位置とスタイルを選びます。',
+  'settings.openchamber.desktopNetwork.field.windowControlsPosition': '位置',
   'settings.openchamber.desktopNetwork.field.windowControlsPositionAria': 'ウィンドウコントロールの位置',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyle': 'スタイル',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyleAria': 'ウィンドウコントロールのスタイル',
   'settings.openchamber.desktopNetwork.option.windowControlsLeft': '左',
   'settings.openchamber.desktopNetwork.option.windowControlsRight': '右',
+  'settings.openchamber.desktopNetwork.option.windowControlsClassic': 'クラシック',
+  'settings.openchamber.desktopNetwork.option.windowControlsTrafficLights': 'トラフィックライト',
   'settings.openchamber.desktopNetwork.field.launchAtLoginAria': 'ログイン時に OpenChamber を起動',
   'settings.openchamber.desktopNetwork.field.launchAtLogin': 'ログイン時に OpenChamber を起動',
   'settings.openchamber.desktopNetwork.field.launchAtLoginDescription': 'ウィンドウを開かずにバックグラウンドでアプリを起動します。デスクトップのステータスアイコンから開けます。',

packages/ui/src/lib/i18n/messages/ko.settings.ts

@@ -912,11 +912,16 @@ export const settingsDict = {
   'settings.openchamber.sessionRetention.toast.failedArchiveCount': '세션 {count}개를 보관하지 못했습니다',
   'settings.openchamber.sessionRetention.toast.failedDeleteCount': '세션 {count}개를 삭제하지 못했습니다',
   'settings.openchamber.desktopNetwork.title': 'Desktop 네트워크 접속',
-  'settings.openchamber.desktopNetwork.field.windowControlsPosition': '창 컨트롤 위치',
-  'settings.openchamber.desktopNetwork.field.windowControlsPositionDescription': '최소화, 최대화, 닫기 버튼이 표시될 위치를 선택합니다. 기본값은 오른쪽입니다.',
+  'settings.openchamber.desktopNetwork.field.windowControls': '창 컨트롤',
+  'settings.openchamber.desktopNetwork.field.windowControlsDescription': '창 컨트롤의 위치와 모양을 선택합니다.',
+  'settings.openchamber.desktopNetwork.field.windowControlsPosition': '위치',
   'settings.openchamber.desktopNetwork.field.windowControlsPositionAria': '창 컨트롤 위치',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyle': '스타일',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyleAria': '창 컨트롤 스타일',
   'settings.openchamber.desktopNetwork.option.windowControlsLeft': '왼쪽',
   'settings.openchamber.desktopNetwork.option.windowControlsRight': '오른쪽',
+  'settings.openchamber.desktopNetwork.option.windowControlsClassic': '클래식',
+  'settings.openchamber.desktopNetwork.option.windowControlsTrafficLights': '트래픽 라이트',
   'settings.openchamber.desktopNetwork.field.launchAtLoginAria': '로그인 시 OpenChamber 시작',
   'settings.openchamber.desktopNetwork.field.launchAtLogin': '로그인 시 OpenChamber 시작',
   'settings.openchamber.desktopNetwork.field.launchAtLoginDescription': '창을 열지 않고 백그라운드에서 앱을 시작합니다. 데스크톱 상태 아이콘으로 열 수 있습니다.',

packages/ui/src/lib/i18n/messages/pl.settings.ts

@@ -780,11 +780,16 @@ export const settingsDict = {
   'settings.openchamber.desktopNetwork.hint.openAfterRestart': 'Po restarcie otwórz z innego urządzenia: ',
   'settings.openchamber.desktopNetwork.hint.openNow': 'Otwórz z innego urządzenia: ',
   'settings.openchamber.desktopNetwork.title': 'Dostęp sieciowy pulpitu',
-  'settings.openchamber.desktopNetwork.field.windowControlsPosition': 'Pozycja elementów sterujących oknem',
-  'settings.openchamber.desktopNetwork.field.windowControlsPositionDescription': 'Wybierz, gdzie mają się pojawiać przyciski minimalizacji, maksymalizacji i zamykania. Domyślnie po prawej.',
+  'settings.openchamber.desktopNetwork.field.windowControls': 'Elementy sterujące oknem',
+  'settings.openchamber.desktopNetwork.field.windowControlsDescription': 'Wybierz, gdzie mają się pojawiać elementy sterujące oknem i jak mają wyglądać.',
+  'settings.openchamber.desktopNetwork.field.windowControlsPosition': 'Pozycja',
   'settings.openchamber.desktopNetwork.field.windowControlsPositionAria': 'Pozycja elementów sterujących oknem',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyle': 'Styl',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyleAria': 'Styl elementów sterujących oknem',
   'settings.openchamber.desktopNetwork.option.windowControlsLeft': 'Lewo',
   'settings.openchamber.desktopNetwork.option.windowControlsRight': 'Prawo',
+  'settings.openchamber.desktopNetwork.option.windowControlsClassic': 'Klasyczny',
+  'settings.openchamber.desktopNetwork.option.windowControlsTrafficLights': 'Sygnalizacja świetlna',
   'settings.openchamber.git.changesViewAria': 'Tryb widoku zmian Git',
   'settings.openchamber.git.changesViewTitle': 'Widok zmian',
   'settings.openchamber.git.enableGitmoji': 'Włącz wybieranie Gitmoji',

packages/ui/src/lib/i18n/messages/pt-BR.settings.ts

@@ -912,11 +912,16 @@ export const settingsDict = {
   "settings.openchamber.sessionRetention.toast.failedArchiveCount": "Não foi possível arquivar {count} sessão(es)",
   "settings.openchamber.sessionRetention.toast.failedDeleteCount": "Não foi possível excluir {count} sessão(es)",
   "settings.openchamber.desktopNetwork.title": "Acesso de rede do desktop",
-  "settings.openchamber.desktopNetwork.field.windowControlsPosition": "Posição dos controles da janela",
-  "settings.openchamber.desktopNetwork.field.windowControlsPositionDescription": "Escolha onde os botões de minimizar, maximizar e fechar aparecem. O padrão é à direita.",
+  "settings.openchamber.desktopNetwork.field.windowControls": "Controles da janela",
+  "settings.openchamber.desktopNetwork.field.windowControlsDescription": "Escolha onde os controles da janela aparecem e como eles são exibidos.",
+  "settings.openchamber.desktopNetwork.field.windowControlsPosition": "Posição",
   "settings.openchamber.desktopNetwork.field.windowControlsPositionAria": "Posição dos controles da janela",
+  "settings.openchamber.desktopNetwork.field.windowControlsStyle": "Estilo",
+  "settings.openchamber.desktopNetwork.field.windowControlsStyleAria": "Estilo dos controles da janela",
   "settings.openchamber.desktopNetwork.option.windowControlsLeft": "Esquerda",
   "settings.openchamber.desktopNetwork.option.windowControlsRight": "Direita",
+  "settings.openchamber.desktopNetwork.option.windowControlsClassic": "Clássico",
+  "settings.openchamber.desktopNetwork.option.windowControlsTrafficLights": "Semáforo",
   "settings.openchamber.desktopNetwork.field.launchAtLoginAria": "Iniciar o OpenChamber ao fazer login",
   "settings.openchamber.desktopNetwork.field.launchAtLogin": "Iniciar o OpenChamber ao fazer login",
   "settings.openchamber.desktopNetwork.field.launchAtLoginDescription": "Inicia o app em segundo plano sem abrir uma janela. Use o ícone de status da área de trabalho para abrir.",

packages/ui/src/lib/i18n/messages/uk.settings.ts

@@ -912,11 +912,16 @@ export const settingsDict = {
   "settings.openchamber.sessionRetention.toast.failedArchiveCount": "Не вдалося заархівувати сесій: {count}",
   "settings.openchamber.sessionRetention.toast.failedDeleteCount": "Не вдалося видалити сесій: {count}",
   "settings.openchamber.desktopNetwork.title": "Мережевий доступ десктопного застосунку",
-  "settings.openchamber.desktopNetwork.field.windowControlsPosition": "Позиція елементів керування вікном",
-  "settings.openchamber.desktopNetwork.field.windowControlsPositionDescription": "Виберіть, де з’являються кнопки згортання, розгортання та закриття. За замовчуванням справа.",
+  "settings.openchamber.desktopNetwork.field.windowControls": "Елементи керування вікном",
+  "settings.openchamber.desktopNetwork.field.windowControlsDescription": "Виберіть, де з’являються елементи керування вікном і як вони виглядають.",
+  "settings.openchamber.desktopNetwork.field.windowControlsPosition": "Позиція",
   "settings.openchamber.desktopNetwork.field.windowControlsPositionAria": "Позиція елементів керування вікном",
+  "settings.openchamber.desktopNetwork.field.windowControlsStyle": "Стиль",
+  "settings.openchamber.desktopNetwork.field.windowControlsStyleAria": "Стиль елементів керування вікном",
   "settings.openchamber.desktopNetwork.option.windowControlsLeft": "Зліва",
   "settings.openchamber.desktopNetwork.option.windowControlsRight": "Справа",
+  "settings.openchamber.desktopNetwork.option.windowControlsClassic": "Класичний",
+  "settings.openchamber.desktopNetwork.option.windowControlsTrafficLights": "Світлофор",
   "settings.openchamber.desktopNetwork.field.launchAtLoginAria": "Запускати OpenChamber під час входу в систему",
   "settings.openchamber.desktopNetwork.field.launchAtLogin": "Запускати OpenChamber під час входу в систему",
   "settings.openchamber.desktopNetwork.field.launchAtLoginDescription": "Запускає застосунок у фоні без відкриття вікна. Відкрийте його через піктограму стану на робочому столі.",

packages/ui/src/lib/i18n/messages/zh-CN.settings.ts

@@ -912,11 +912,16 @@ export const settingsDict = {
   'settings.openchamber.sessionRetention.toast.failedArchiveCount': '归档 {count} 个会话失败',
   'settings.openchamber.sessionRetention.toast.failedDeleteCount': '删除 {count} 个会话失败',
   'settings.openchamber.desktopNetwork.title': '桌面端网络访问',
-  'settings.openchamber.desktopNetwork.field.windowControlsPosition': '窗口控件位置',
-  'settings.openchamber.desktopNetwork.field.windowControlsPositionDescription': '选择最小化、最大化和关闭按钮的显示位置。默认在右侧。',
+  'settings.openchamber.desktopNetwork.field.windowControls': '窗口控件',
+  'settings.openchamber.desktopNetwork.field.windowControlsDescription': '选择窗口控件的位置和外观。',
+  'settings.openchamber.desktopNetwork.field.windowControlsPosition': '位置',
   'settings.openchamber.desktopNetwork.field.windowControlsPositionAria': '窗口控件位置',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyle': '样式',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyleAria': '窗口控件样式',
   'settings.openchamber.desktopNetwork.option.windowControlsLeft': '左侧',
   'settings.openchamber.desktopNetwork.option.windowControlsRight': '右侧',
+  'settings.openchamber.desktopNetwork.option.windowControlsClassic': '经典',
+  'settings.openchamber.desktopNetwork.option.windowControlsTrafficLights': '红绿灯',
   'settings.openchamber.desktopNetwork.field.launchAtLoginAria': '登录时启动 OpenChamber',
   'settings.openchamber.desktopNetwork.field.launchAtLogin': '登录时启动 OpenChamber',
   'settings.openchamber.desktopNetwork.field.launchAtLoginDescription': '在后台启动应用且不打开窗口。可通过桌面状态图标打开。',

packages/ui/src/lib/i18n/messages/zh-TW.settings.ts

@@ -909,11 +909,16 @@
   'settings.openchamber.sessionRetention.toast.failedArchiveCount': '封存 {count} 個工作階段失敗',
   'settings.openchamber.sessionRetention.toast.failedDeleteCount': '刪除 {count} 個工作階段失敗',
   'settings.openchamber.desktopNetwork.title': '桌面端網路存取',
-  'settings.openchamber.desktopNetwork.field.windowControlsPosition': '視窗控制項位置',
-  'settings.openchamber.desktopNetwork.field.windowControlsPositionDescription': '選擇最小化、最大化和關閉按鈕的顯示位置。預設在右側。',
+  'settings.openchamber.desktopNetwork.field.windowControls': '視窗控制項',
+  'settings.openchamber.desktopNetwork.field.windowControlsDescription': '選擇視窗控制項的位置和外觀。',
+  'settings.openchamber.desktopNetwork.field.windowControlsPosition': '位置',
   'settings.openchamber.desktopNetwork.field.windowControlsPositionAria': '視窗控制項位置',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyle': '樣式',
+  'settings.openchamber.desktopNetwork.field.windowControlsStyleAria': '視窗控制項樣式',
   'settings.openchamber.desktopNetwork.option.windowControlsLeft': '左側',
   'settings.openchamber.desktopNetwork.option.windowControlsRight': '右側',
+  'settings.openchamber.desktopNetwork.option.windowControlsClassic': '經典',
+  'settings.openchamber.desktopNetwork.option.windowControlsTrafficLights': '紅綠燈',
   'settings.openchamber.desktopNetwork.field.allowLanAccessAria': '允許桌面 sidecar 區域網路存取',
   'settings.openchamber.desktopNetwork.field.allowLanAccess': '允許你本機網路中的其他裝置開啟此應用程式',
   'settings.openchamber.desktopNetwork.field.allowLanAccessDescription': '會重新啟動應用程式，以便手機、平板和同一 Wi‑Fi 下的其他電腦存取。',

packages/ui/src/lib/persistence.ts

@@ -557,6 +557,7 @@ const materializeAuthoritativeUiSettings = (settings: DesktopSettings): DesktopS
     timeFormatPreference: defaults.timeFormatPreference,
     weekStartPreference: defaults.weekStartPreference,
     desktopWindowControlsPosition: defaults.desktopWindowControlsPosition,
+    desktopWindowControlsStyle: defaults.desktopWindowControlsStyle,
     chatRenderMode: defaults.chatRenderMode,
     activityRenderMode: defaults.activityRenderMode,
     mermaidRenderingMode: defaults.mermaidRenderingMode,
@@ -748,6 +749,16 @@ const applyDesktopUiPreferences = (settings: DesktopSettings) => {
       store.setDesktopWindowControlsPosition(nextPosition);
     }
   }
+  if (typeof settings.desktopWindowControlsStyle === 'string') {
+    const nextStyle = settings.desktopWindowControlsStyle === 'traffic-lights'
+      ? 'traffic-lights'
+      : settings.desktopWindowControlsStyle === 'classic'
+        ? 'classic'
+        : null;
+    if (nextStyle && nextStyle !== store.desktopWindowControlsStyle) {
+      store.setDesktopWindowControlsStyle(nextStyle);
+    }
+  }
   if (typeof settings.chatRenderMode === 'string'
     && (settings.chatRenderMode === 'sorted' || settings.chatRenderMode === 'live')) {
     if (settings.chatRenderMode !== store.chatRenderMode) {
@@ -1379,6 +1390,11 @@ const sanitizeWebSettings = (payload: unknown): DesktopSettings | null => {
       result.desktopWindowControlsPosition = 'right';
     }
   }
+  if (typeof candidate.desktopWindowControlsStyle === 'string') {
+    if (candidate.desktopWindowControlsStyle === 'classic' || candidate.desktopWindowControlsStyle === 'traffic-lights') {
+      result.desktopWindowControlsStyle = candidate.desktopWindowControlsStyle;
+    }
+  }
   if (typeof candidate.chatRenderMode === 'string'
     && (candidate.chatRenderMode === 'sorted' || candidate.chatRenderMode === 'live')) {
     result.chatRenderMode = candidate.chatRenderMode;

packages/ui/src/lib/settings/search.ts

@@ -399,9 +399,16 @@ const SETTINGS_SEARCH_ITEMS: readonly SettingsSearchItem[] = [
   {
     id: 'sessions.desktop-window-controls-position',
     page: 'appearance',
-    titleKey: 'settings.openchamber.desktopNetwork.field.windowControlsPosition',
-    descriptionKey: 'settings.openchamber.desktopNetwork.field.windowControlsPositionDescription',
-    keywords: ['desktop', 'window', 'controls', 'minimize', 'maximize', 'close', 'titlebar', 'linux', 'windows'],
+    titleKey: 'settings.openchamber.desktopNetwork.field.windowControls',
+    descriptionKey: 'settings.openchamber.desktopNetwork.field.windowControlsDescription',
+    keywords: ['desktop', 'window', 'controls', 'minimize', 'maximize', 'close', 'titlebar', 'linux', 'windows', 'position'],
+    isAvailable: (ctx) => ctx.isDesktop && (ctx.isWindows || !ctx.isMac),
+  },
+  {
+    id: 'sessions.desktop-window-controls-style',
+    page: 'appearance',
+    titleKey: 'settings.openchamber.desktopNetwork.field.windowControlsStyle',
+    keywords: ['desktop', 'window', 'controls', 'style', 'traffic', 'lights', 'classic', 'macos', 'titlebar'],
     isAvailable: (ctx) => ctx.isDesktop && (ctx.isWindows || !ctx.isMac),
   },
   {

packages/ui/src/main.tsx

@@ -13,6 +13,7 @@ import { applyPersistedDirectoryPreferences } from './lib/directoryPersistence'
 import { startTypographyWatcher } from './lib/typographyWatcher'
 import { startModelPrefsAutoSave } from './lib/modelPrefsAutoSave'
 import { initializeLocale, I18nProvider } from './lib/i18n'
+import { initLinuxWindowBorder } from './lib/desktop'
 import type { RuntimeAPIs } from './lib/api/types'
 
 declare global {
@@ -26,6 +27,7 @@ const runtimeAPIs = (typeof window !== 'undefined' && window.__OPENCHAMBER_RUNTI
 })();
 
 initializeLocale();
+initLinuxWindowBorder();
 
 // Initialize settings asynchronously — the app renders with defaults first
 // and hydrates once persisted preferences are applied. Users with non-default

packages/ui/src/stores/useUIStore.ts

@@ -22,6 +22,7 @@ export type SessionRetentionAction = 'archive' | 'delete';
 export type TimeFormatPreference = 'auto' | '12h' | '24h';
 export type WeekStartPreference = 'auto' | 'sunday' | 'monday';
 export type DesktopWindowControlsPosition = 'left' | 'right';
+export type DesktopWindowControlsStyle = 'classic' | 'traffic-lights';
 export type FileEditorKeymap = 'default' | 'vim';
 
 function normalizeFileEditorKeymap(value: unknown): FileEditorKeymap {
@@ -693,6 +694,7 @@ interface UIStore {
   timeFormatPreference: TimeFormatPreference;
   weekStartPreference: WeekStartPreference;
   desktopWindowControlsPosition: DesktopWindowControlsPosition;
+  desktopWindowControlsStyle: DesktopWindowControlsStyle;
   mermaidRenderingMode: MermaidRenderingMode;
   userMessageRenderingMode: UserMessageRenderingMode;
   collapsibleUserMessages: boolean;
@@ -854,6 +856,7 @@ interface UIStore {
   setTimeFormatPreference: (value: TimeFormatPreference) => void;
   setWeekStartPreference: (value: WeekStartPreference) => void;
   setDesktopWindowControlsPosition: (value: DesktopWindowControlsPosition) => void;
+  setDesktopWindowControlsStyle: (value: DesktopWindowControlsStyle) => void;
   setMermaidRenderingMode: (value: MermaidRenderingMode) => void;
   setUserMessageRenderingMode: (value: UserMessageRenderingMode) => void;
   setCollapsibleUserMessages: (value: boolean) => void;
@@ -1004,6 +1007,7 @@ export const useUIStore = create<UIStore>()(
         timeFormatPreference: 'auto',
         weekStartPreference: 'auto',
         desktopWindowControlsPosition: 'right',
+        desktopWindowControlsStyle: 'classic',
         mermaidRenderingMode: 'svg',
         userMessageRenderingMode: 'markdown',
         collapsibleUserMessages: true,
@@ -2169,6 +2173,9 @@ export const useUIStore = create<UIStore>()(
         setDesktopWindowControlsPosition: (value) => {
           set({ desktopWindowControlsPosition: value === 'left' ? 'left' : 'right' });
         },
+        setDesktopWindowControlsStyle: (value) => {
+          set({ desktopWindowControlsStyle: value === 'traffic-lights' ? 'traffic-lights' : 'classic' });
+        },
         setMermaidRenderingMode: (value) => {
           set({ mermaidRenderingMode: value });
         },
@@ -2247,7 +2254,7 @@ export const useUIStore = create<UIStore>()(
       {
         name: 'ui-store',
         storage: createDeferredSafeJSONStorage(),
-        version: 12,
+        version: 13,
         migrate: (persistedState, version) => {
           if (!persistedState || typeof persistedState !== 'object') {
             return persistedState;
@@ -2261,6 +2268,15 @@ export const useUIStore = create<UIStore>()(
             }
           }
 
+          // v12 -> v13: introduce window-controls style. Existing users keep
+          // their persisted position; style defaults to "classic" so no one
+          // suddenly sees traffic lights on upgrade.
+          if (version < 13) {
+            if (state.desktopWindowControlsStyle !== 'classic' && state.desktopWindowControlsStyle !== 'traffic-lights') {
+              state.desktopWindowControlsStyle = 'classic';
+            }
+          }
+
           // v10 -> v11: move the previous terminal font default forward.
           if (version < 11 && state.terminalFontSize === 13) {
             state.terminalFontSize = 14;
@@ -2439,6 +2455,7 @@ export const useUIStore = create<UIStore>()(
           timeFormatPreference: state.timeFormatPreference,
           weekStartPreference: state.weekStartPreference,
           desktopWindowControlsPosition: state.desktopWindowControlsPosition,
+          desktopWindowControlsStyle: state.desktopWindowControlsStyle,
           mermaidRenderingMode: state.mermaidRenderingMode,
           userMessageRenderingMode: state.userMessageRenderingMode,
           collapsibleUserMessages: state.collapsibleUserMessages,

packages/web/server/lib/opencode/settings-helpers.js

@@ -197,6 +197,12 @@ export const createSettingsHelpers = (dependencies) => {
         result.desktopWindowControlsPosition = 'left';
       }
     }
+    if (typeof candidate.desktopWindowControlsStyle === 'string') {
+      const style = candidate.desktopWindowControlsStyle.trim();
+      if (style === 'classic' || style === 'traffic-lights') {
+        result.desktopWindowControlsStyle = style;
+      }
+    }
     if (candidate.permissionAutoAccept && typeof candidate.permissionAutoAccept === 'object' && !Array.isArray(candidate.permissionAutoAccept)) {
       const sessions = {};
       const sourceSessions = candidate.permissionAutoAccept.sessions;

packages/web/server/lib/opencode/settings-helpers.test.js

@@ -169,6 +169,19 @@ describe('settings helpers', () => {
     expect(helpers.sanitizeSettingsUpdate({ desktopWindowControlsPosition: 'center' })).toEqual({});
   });
 
+  it('sanitizes desktopWindowControlsStyle and rejects unknown values', () => {
+    const helpers = createTestHelpers();
+
+    expect(helpers.sanitizeSettingsUpdate({ desktopWindowControlsStyle: 'classic' })).toEqual({
+      desktopWindowControlsStyle: 'classic',
+    });
+    expect(helpers.sanitizeSettingsUpdate({ desktopWindowControlsStyle: 'traffic-lights' })).toEqual({
+      desktopWindowControlsStyle: 'traffic-lights',
+    });
+    expect(helpers.sanitizeSettingsUpdate({ desktopWindowControlsStyle: 'macos' })).toEqual({});
+    expect(helpers.sanitizeSettingsUpdate({ desktopWindowControlsStyle: 'auto' })).toEqual({});
+  });
+
   it('sanitizes the persisted permission auto-accept policy', () => {
     const helpers = createTestHelpers();