diff --git a/frontend/src/app/components/RunInDesktopMessage.tsx b/frontend/src/app/components/RunInDesktopMessage.tsx
new file mode 100644
index 00000000..2237c415
--- /dev/null
+++ b/frontend/src/app/components/RunInDesktopMessage.tsx
@@ -0,0 +1,38 @@
+import React from 'react';
+import Box from '@mui/material/Box';
+import Typography from '@mui/material/Typography';
+
+interface Props {
+  kind?: 'browser' | 'app';
+}
+
+// Shown when a browser/app card is rendered OUTSIDE Electron (the dev URL opened directly in a web browser). The real <webview> only exists in the desktop app; rather than a crippled <iframe> the agent can't drive, tell the user to launch correctly.
+const RunInDesktopMessage: React.FC<Props> = ({ kind = 'browser' }) => {
+  const noun = kind === 'app' ? 'Apps' : 'Browsers';
+  return (
+    <Box
+      sx={{
+        width: '100%',
+        height: '100%',
+        display: 'flex',
+        flexDirection: 'column',
+        alignItems: 'center',
+        justifyContent: 'center',
+        gap: 1,
+        px: 3,
+        textAlign: 'center',
+        color: '#888',
+        userSelect: 'none',
+      }}
+    >
+      <Typography sx={{ fontSize: '0.95rem', fontWeight: 600, color: '#bbb' }}>
+        Open this in the OpenSwarm desktop app
+      </Typography>
+      <Typography sx={{ fontSize: '0.82rem', lineHeight: 1.5, maxWidth: 360 }}>
+        {noun} run inside the OpenSwarm desktop window, not a regular web browser. It looks like you opened the dev URL directly in a browser; launch OpenSwarm (the Electron window from <code>bash run.sh</code>) and use it there instead.
+      </Typography>
+    </Box>
+  );
+};
+
+export default RunInDesktopMessage;
diff --git a/frontend/src/app/pages/Dashboard/cards/BrowserCard.tsx b/frontend/src/app/pages/Dashboard/cards/BrowserCard.tsx
index b7a16fa0..4334d3ac 100644
--- a/frontend/src/app/pages/Dashboard/cards/BrowserCard.tsx
+++ b/frontend/src/app/pages/Dashboard/cards/BrowserCard.tsx
@@ -21,6 +21,7 @@ import AddIcon from '@mui/icons-material/Add';
 import LockIcon from '@mui/icons-material/Lock';
 import SearchIcon from '@mui/icons-material/Search';
 import SmartToyOutlinedIcon from '@mui/icons-material/SmartToyOutlined';
+import RunInDesktopMessage from '@/app/components/RunInDesktopMessage';
 import {
   setBrowserCardPosition,
   setBrowserCardSize,
@@ -120,7 +121,8 @@ function markWindowsWebviewSurvived(): void {
 }
 
 const isWindows = navigator.userAgent.includes('Windows');
-const isElectron = navigator.userAgent.includes('Electron') && (!isWindows || windowsWebviewEnabled());
+const inElectron = navigator.userAgent.includes('Electron');
+const isElectron = inElectron && (!isWindows || windowsWebviewEnabled());
 
 // Keep the openswarm/<ver> product token: Google's sign-in flags a BARE Chrome UA as not-genuine-Chrome and blocks it ("browser may not be secure"), but tolerates a UA carrying a product token. Only the Electron token must go (that one Google hard-blocks).
 const chromeUserAgent = navigator.userAgent
@@ -1325,11 +1327,11 @@ const BrowserCard: React.FC<Props> = ({
             </Button>
           </DialogActions>
         </Dialog>
-        {!isElectron && (
+        {!isElectron && (inElectron ? (
+          // inElectron but !isElectron = Windows after the webview crashed (windowsWebviewEnabled() false); keep the iframe as the crash safety net. No sandbox so sites render; the renderer's already isolated by Electron + the main.js XFO/CSP strip.
           <Box sx={{ width: '100%', height: '100%', position: 'relative' }}>
             <iframe
               src={activeUrl}
-              // No sandbox: a restrictive sandbox blocks some sites from rendering, and our renderer is already isolated by Electron's contextIsolation + sub_frame XFO/CSP frame-ancestors strip in main.js. onLoad/onError add definitive instrumentation so we can tell whether the iframe loaded successfully (with empty body from anti-iframe JS) or genuinely failed (network error, CSP block, etc.).
               style={{ width: '100%', height: '100%', border: 'none', pointerEvents: isElementSelectMode ? 'none' : 'auto' }}
               title="Browser"
               referrerPolicy="no-referrer-when-downgrade"
@@ -1339,7 +1341,9 @@ const BrowserCard: React.FC<Props> = ({
               }}
             />
           </Box>
-        )}
+        ) : (
+          <RunInDesktopMessage kind="browser" />
+        ))}
 
         {/* Camera flash: screenshot */}
         {(agentAction === 'screenshot' || lastAction === 'screenshot') && (
diff --git a/frontend/src/app/pages/Views/ViewPreview.tsx b/frontend/src/app/pages/Views/ViewPreview.tsx
index a778aa05..a656d5b7 100644
--- a/frontend/src/app/pages/Views/ViewPreview.tsx
+++ b/frontend/src/app/pages/Views/ViewPreview.tsx
@@ -7,8 +7,9 @@ import { useIframeElementSelector } from './useIframeElementSelector';
 import { getAuthToken, ensureAuthToken } from '@/shared/config';
 import { useClaudeTokens } from '@/shared/styles/ThemeContext';
 import { registerViewWebview, unregisterViewWebview, type ViewWebview } from '@/shared/viewWebviewRegistry';
+import RunInDesktopMessage from '@/app/components/RunInDesktopMessage';
 
-// In Electron use <webview> to escape iframe restrictions (popups, mic/camera, WebAuthn, cookied fetch); outside Electron fall back to iframe.
+// In Electron use <webview> to escape iframe restrictions (popups, mic/camera, WebAuthn, cookied fetch); a srcdoc app still uses an iframe (data:text/html breaks webview same-origin); outside Electron we show a launch-correctly message.
 const isElectron = navigator.userAgent.includes('Electron');
 
 // Card previews render small; downscale + JPEG so thumbnails don't bloat the output JSON or every list fetch.
@@ -411,7 +412,8 @@ const ViewPreview = forwardRef<ViewPreviewHandle, Props>(({
             ...style,
           }}
         />
-      ) : (
+      ) : isElectron ? (
+        // In Electron but not useWebview = a srcdoc app (no serveUrl); the iframe is REQUIRED here (data:text/html breaks webview same-origin), not a fallback. Non-Electron falls through to the launch-correctly message.
         <iframe
           ref={iframeRef}
           // Key only changes on mode switch (URL vs srcdoc); reloadKey updates the src attribute in place to avoid blank-flash on reload.
@@ -429,6 +431,8 @@ const ViewPreview = forwardRef<ViewPreviewHandle, Props>(({
           }}
           title="App Preview"
         />
+      ) : (
+        <RunInDesktopMessage kind="app" />
       )}
       {restoring && (
         <Box