fix(desktop): fullscreen header bar + always-visible close controls (#8033)

Signed-off-by: Andrew Harvard <aharvard@squareup.com>
Signed-off-by: Douwe Osinga <douwe@squareup.com>
Co-authored-by: Goose <opensource@block.xyz>
Co-authored-by: Douwe Osinga <douwe@squareup.com>

crates/goose-mcp/src/autovisualiser/templates/assets/mcp-app-bridge.js

@@ -192,12 +192,10 @@ var McpAppBridge = (function () {
     };
     sendRequest("ui/initialize", {
       protocolVersion: "2026-01-26",
-      appInfo: appIdentity,
       clientInfo: appIdentity,
       appCapabilities: {
         availableDisplayModes: ["inline", "fullscreen"],
       },
-      capabilities: {},
     })
       .then(function (result) {
         applyTheme(result.hostContext || result);

ui/desktop/src/components/McpApps/McpAppRenderer.tsx

@@ -33,6 +33,7 @@ import { cn } from '../../utils';
 import { errorMessage } from '../../utils/conversionUtils';
 import { getProtocol, isProtocolSafe } from '../../utils/urlSecurity';
 import FlyingBird from '../FlyingBird';
+import { formatExtensionName } from '../settings/extensions/subcomponents/ExtensionList';
 import {
   GooseDisplayMode,
   SandboxPermissions,
@@ -54,6 +55,7 @@ import {
 } from './useDisplayMode';
 
 const DEFAULT_IFRAME_HEIGHT = 200;
+const FULLSCREEN_HEADER_HEIGHT = 48;
 
 const DISPLAY_MODE_LAYOUTS: Record<GooseDisplayMode, DimensionLayout> = {
   inline: { width: 'fixed', height: 'unbounded' },
@@ -246,6 +248,7 @@ export default function McpAppRenderer({
   onDisplayModeChange,
 }: McpAppRendererProps) {
   const containerRef = useRef<HTMLDivElement>(null);
+  const contentRef = useRef<HTMLDivElement>(null);
 
   const dm = useDisplayMode({ displayMode, onDisplayModeChange, containerRef });
   const {
@@ -258,6 +261,7 @@ export default function McpAppRenderer({
     isInline,
     appSupportsFullscreen,
     appSupportsPip,
+    appTitle,
     changeDisplayMode,
     inlineHeight,
     pipPosition,
@@ -672,7 +676,7 @@ export default function McpAppRenderer({
       containerDimensions: getContainerDimensions(
         activeDisplayMode,
         containerWidth,
-        containerHeight
+        isFullscreen ? containerHeight - FULLSCREEN_HEADER_HEIGHT : containerHeight
       ),
       locale: navigator.language,
       timeZone: Intl.DateTimeFormat().resolvedOptions().timeZone,
@@ -695,6 +699,7 @@ export default function McpAppRenderer({
     resolvedTheme,
     mcpHostStyles,
     activeDisplayMode,
+    isFullscreen,
     isStandalone,
     containerWidth,
     containerHeight,
@@ -754,36 +759,53 @@ export default function McpAppRenderer({
     );
   };
 
-  const showControls = !isStandalone && !isError && (appSupportsFullscreen || appSupportsPip);
+  const showControls =
+    !isStandalone && !isError && (appSupportsFullscreen || appSupportsPip || isFullscreen || isPip);
+
+  const fullscreenTitle = useMemo(() => {
+    if (appTitle) return appTitle;
+    if (extensionName) return formatExtensionName(extensionName);
+    return 'App';
+  }, [appTitle, extensionName]);
+
+  const renderFullscreenHeader = () => (
+    <div
+      className="flex shrink-0 items-center border-b border-border-primary bg-background-primary px-3"
+      style={{ height: `${FULLSCREEN_HEADER_HEIGHT}px` }}
+    >
+      <div className="min-w-0 flex-1" />
+      <span className="truncate px-4 text-sm font-medium text-text-secondary">
+        {fullscreenTitle}
+      </span>
+      <div className="flex flex-1 items-center justify-end gap-1">
+        {appSupportsPip && (
+          <button
+            onClick={() => changeDisplayMode('pip')}
+            className="no-drag cursor-pointer rounded-md p-1.5 text-text-secondary transition-colors hover:bg-black/10 hover:text-text-primary dark:hover:bg-white/10"
+            title="Picture-in-Picture"
+            aria-label="Picture-in-Picture"
+          >
+            <PictureInPicture2 size={16} />
+          </button>
+        )}
+        <button
+          ref={fullscreenCloseRef}
+          onClick={() => changeDisplayMode('inline')}
+          className="no-drag cursor-pointer rounded-md p-1.5 text-text-secondary transition-colors hover:bg-black/10 hover:text-text-primary dark:hover:bg-white/10"
+          title="Exit fullscreen (Esc)"
+          aria-label="Exit fullscreen"
+        >
+          <X size={16} />
+        </button>
+      </div>
+    </div>
+  );
 
   const renderDisplayModeControls = () => {
     if (!showControls) return null;
 
-    if (activeDisplayMode === 'fullscreen') {
-      return (
-        <div className="no-drag absolute top-3 right-3 z-[60] flex gap-1">
-          {appSupportsPip && (
-            <button
-              onClick={() => changeDisplayMode('pip')}
-              className="cursor-pointer rounded-md bg-black/50 p-1.5 text-white backdrop-blur-sm transition-opacity hover:bg-black/70"
-              title="Picture-in-Picture"
-              aria-label="Picture-in-Picture"
-            >
-              <PictureInPicture2 size={16} />
-            </button>
-          )}
-          <button
-            ref={fullscreenCloseRef}
-            onClick={() => changeDisplayMode('inline')}
-            className="cursor-pointer rounded-md bg-black/50 p-1.5 text-white backdrop-blur-sm transition-opacity hover:bg-black/70"
-            title="Exit fullscreen (Esc)"
-            aria-label="Exit fullscreen"
-          >
-            <X size={16} />
-          </button>
-        </div>
-      );
-    }
+    // Fullscreen controls are rendered by renderFullscreenHeader instead.
+    if (activeDisplayMode === 'fullscreen') return null;
 
     if (activeDisplayMode === 'pip') {
       return (
@@ -893,9 +915,10 @@ export default function McpAppRenderer({
       {/* Stable app container — never unmounted, only repositioned via CSS */}
       <div
         ref={containerRef}
-        className={cn(containerClasses, isPip && 'group/pip')}
+        className={cn(containerClasses, isFillsViewport && 'flex flex-col', isPip && 'group/pip')}
         style={containerStyle}
       >
+        {isFullscreen && renderFullscreenHeader()}
         {isPip && (
           <div className="pointer-events-none sticky top-1 z-20 flex h-0 items-start justify-between px-1 opacity-0 transition-opacity group-hover/pip:pointer-events-auto group-hover/pip:opacity-100 focus-within:pointer-events-auto focus-within:opacity-100">
             <div
@@ -914,7 +937,7 @@ export default function McpAppRenderer({
             <div className="flex gap-1">{renderDisplayModeControls()}</div>
           </div>
         )}
-        <div className={cn('relative w-full', !isPip && 'h-full')}>
+        <div ref={contentRef} className={cn('relative w-full', !isPip && 'flex-1 min-h-0')}>
           {!isPip && renderDisplayModeControls()}
           {renderContent()}
         </div>

ui/desktop/src/components/McpApps/useDisplayMode.ts

@@ -36,6 +36,7 @@ export interface DisplayModeState {
   isInline: boolean;
   appSupportsFullscreen: boolean;
   appSupportsPip: boolean;
+  appTitle: string | null;
 
   changeDisplayMode: (mode: GooseDisplayMode) => void;
 
@@ -77,6 +78,9 @@ export function useDisplayMode({
   // null = not yet known (controls stay hidden until initialize), empty = app didn't declare any.
   const [appDeclaredModes, setAppDeclaredModes] = useState<string[] | null>(null);
 
+  // App-declared title from ui/initialize (highest priority in the title fallback chain).
+  const [appTitle, setAppTitle] = useState<string | null>(null);
+
   const effectiveDisplayModes = useMemo((): McpUiDisplayMode[] => {
     if (!appDeclaredModes) return [];
     return AVAILABLE_DISPLAY_MODES.filter((m) => appDeclaredModes.includes(m));
@@ -263,6 +267,10 @@ export function useDisplayMode({
         if (caps?.availableDisplayModes && Array.isArray(caps.availableDisplayModes)) {
           setAppDeclaredModes(caps.availableDisplayModes);
         }
+        const title = data.params.clientInfo?.name;
+        if (typeof title === 'string' && title.trim()) {
+          setAppTitle(title.trim());
+        }
       }
 
       // After initialize, only allow modes both host and app agree on.
@@ -319,6 +327,7 @@ export function useDisplayMode({
     isInline,
     appSupportsFullscreen,
     appSupportsPip,
+    appTitle,
 
     changeDisplayMode,