nexu-io · lefarcen · Jul 28, 2026 · Jul 28, 2026
diff --git a/apps/web/src/App.tsx b/apps/web/src/App.tsx
@@ -144,7 +144,7 @@ import type {
   PluginShareProjectOutcome,
   WorkspaceProjectListView,
 } from './state/projects';
-import type { OpenDesignHostProjectImportSuccess } from '@open-design/host';
+import { getOpenDesignHost, type OpenDesignHostProjectImportSuccess } from '@open-design/host';
 import { useI18n } from './i18n';
 import { liveArtifactTabId } from './types';
 import type {
@@ -665,6 +665,7 @@ function AppInner() {
   const { t } = useI18n();
   const iframeKeepAlivePool = useIframeKeepAlivePool();
   const clientType = useMemo(() => detectClientType(), []);
+  const hostPlatform = useMemo(() => getOpenDesignHost()?.client.platform, []);
   useModalWindowDragGuard();
   const workspaceContextState = useWorkspaceContext();
   const {
@@ -716,7 +717,11 @@ function AppInner() {
   // scrim to let the wallpaper show through more clearly; on focus the scrim
   // returns to full strength (app-wash.css keys off this class).
   useEffect(() => {
-    if (clientType !== 'desktop' || typeof window === 'undefined') return undefined;
+    if (
+      clientType !== 'desktop'
+      || hostPlatform !== 'darwin'
+      || typeof window === 'undefined'
+    ) return undefined;
     const root = document.documentElement;
     const sync = () => root.classList.toggle('is-window-blurred', !document.hasFocus());
     sync();
@@ -727,7 +732,7 @@ function AppInner() {
       window.removeEventListener('blur', sync);
       root.classList.remove('is-window-blurred');
     };
-  }, [clientType]);
+  }, [clientType, hostPlatform]);
   const [config, setConfig] = useState<AppConfig>(() => loadConfig());
   const configRef = useRef(config);
   configRef.current = config;
@@ -3497,6 +3502,7 @@ function AppInner() {
       <div
         className={`workspace-shell workspace-shell--${clientType}`}
         data-client-type={clientType}
+        data-host-platform={hostPlatform}
       >
         <WorkspaceTabsBar
           route={route}

diff --git a/apps/web/src/styles/app-wash.css b/apps/web/src/styles/app-wash.css
@@ -76,9 +76,10 @@ body::before {
    wallpaper blurs through the window, so the painted pastel blobs step aside.
    html/body go fully transparent and the wash collapses to a translucent
    cream scrim that keeps content readable over arbitrary wallpapers — the
-   Craft look. The .workspace-shell--desktop marker comes from the host
-   bridge (App.tsx data-client-type). Browsers never match this block. */
-html:has(.workspace-shell--desktop) {
+   Craft look. The desktop and darwin markers come from the host bridge
+   (App.tsx data-client-type/data-host-platform). Windows desktop windows are
+   opaque, so they intentionally keep the normal pastel wash. */
+html:has(.workspace-shell--desktop[data-host-platform='darwin']) {
   /* Focused window: a firm scrim so content sits on a mostly solid ground.
      The unfocused state below thins this back to ~21% (0.34 × 62%), which
      preserves the airy see-through look while the window is in the back. */
@@ -88,17 +89,17 @@ html:has(.workspace-shell--desktop) {
   );
   background: transparent;
 }
-html:has(.workspace-shell--desktop) body {
+html:has(.workspace-shell--desktop[data-host-platform='darwin']) body {
   background: transparent;
 }
 /* Focus response: while the window is unfocused (App.tsx toggles
    .is-window-blurred on <html> in desktop mode) the scrim thins out so the
    wallpaper reads clearly through the glass; regaining focus fades it back
    to full strength. Browsers never get the class, so web mode is untouched. */
-html:has(.workspace-shell--desktop) body::before {
+html:has(.workspace-shell--desktop[data-host-platform='darwin']) body::before {
   transition: opacity 240ms cubic-bezier(0.23, 1, 0.32, 1);
 }
-html.is-window-blurred:has(.workspace-shell--desktop) body::before {
+html.is-window-blurred:has(.workspace-shell--desktop[data-host-platform='darwin']) body::before {
   opacity: 0.34;
 }
 /* The top project tab strip stays flush and seamless with the page below it:
@@ -126,8 +127,8 @@ html.is-window-blurred:has(.workspace-shell--desktop) body::before {
     --veil-canvas: var(--bg);
     --veil-panel: var(--bg-panel);
   }
-  html:has(.workspace-shell--desktop),
-  html:has(.workspace-shell--desktop) body {
+  html:has(.workspace-shell--desktop[data-host-platform='darwin']),
+  html:has(.workspace-shell--desktop[data-host-platform='darwin']) body {
     background: var(--bg-app);
   }
 }
@@ -143,8 +144,8 @@ html.is-window-blurred:has(.workspace-shell--desktop) body::before {
     --veil-canvas: var(--bg);
     --veil-panel: var(--bg-panel);
   }
-  html:has(.workspace-shell--desktop),
-  html:has(.workspace-shell--desktop) body {
+  html:has(.workspace-shell--desktop[data-host-platform='darwin']),
+  html:has(.workspace-shell--desktop[data-host-platform='darwin']) body {
     background: var(--bg-app);
   }
 }
diff --git a/apps/web/tests/components/App.update-dialog.test.tsx b/apps/web/tests/components/App.update-dialog.test.tsx
@@ -204,6 +204,23 @@ describe('App updater dialog integration', () => {
     vi.clearAllMocks();
   });
 
+  it('exposes the desktop host platform on the workspace shell', () => {
+    restoreHost = installMockOpenDesignHost({
+      host: {
+        client: {
+          platform: 'win32',
+        },
+      },
+    });
+
+    const { container } = render(<App />);
+
+    expect(container.querySelector('.workspace-shell')).toHaveAttribute(
+      'data-host-platform',
+      'win32',
+    );
+  });
+
   it('mounts the updater open-dialog subscription and handles the mac app menu request', async () => {
     let openDialogListener: OpenDesignHostUpdaterOpenDialogListener | null = null;
     const check = vi.fn(async () => idleStatus({ state: 'not-available' }));

diff --git a/apps/web/tests/styles/app-wash-platform.test.ts b/apps/web/tests/styles/app-wash-platform.test.ts
@@ -0,0 +1,21 @@
+import { readFileSync } from 'node:fs';
+import { describe, expect, it } from 'vitest';
+
+const appWashCss = readFileSync(
+  new URL('../../src/styles/app-wash.css', import.meta.url),
+  'utf8',
+);
+
+describe('desktop app wash platform contract', () => {
+  it('limits window-vibrancy material rules to macOS desktop hosts', () => {
+    const macDesktopSelector =
+      ":has(.workspace-shell--desktop[data-host-platform='darwin'])";
+    const vibrancySelectors = appWashCss.match(
+      /html(?:\.is-window-blurred)?:has\(\.workspace-shell--desktop[^)]*\)(?: body(?:::before)?)?/g,
+    );
+
+    expect(vibrancySelectors).not.toBeNull();
+    expect(vibrancySelectors).not.toHaveLength(0);
+    expect(vibrancySelectors?.every((selector) => selector.includes(macDesktopSelector))).toBe(true);
+  });
+});