[eric] crash: quiesce+detach outgoing webviews before dashboard-switch resetLayout (it unmounted every app/browser webview in one frame w/ CDP attached = GPU/browser SIGSEGV, the 'navigate away kills the app' self-quit)

frontend/src/app/pages/Dashboard/hooks/lifecycle/useDashboardLifecycle.ts

@@ -29,6 +29,7 @@ import { fetchProviderHealth } from '@/shared/state/subscriptionsSlice';
 import { dashboardWs } from '@/shared/ws/WebSocketManager';
 import { initBrowserCommandHandler } from '@/shared/browserCommandHandler';
 import { getKeepAliveBrowserIds } from '@/shared/browserFocus';
+import { prepareDashboardSwitch } from '@/shared/dashboardSwitchTeardown';
 import { clearPendingBrowserUrl, clearPendingFocusAgentId } from '@/shared/state/tempStateSlice';
 import { API_BASE } from '@/shared/config';
 import type { CanvasActions } from '../interaction/useCanvasControls';
@@ -118,10 +119,16 @@ export function useDashboardLifecycle({
       hasFittedRef.current = false;
       restoredExpandedRef.current = false;
       setOutputsRefetched(false);
-      dispatch(resetLayout({ keepBrowserIds: getKeepAliveBrowserIds() }));
-      // CRITICAL path: these populate the cards the user expects to see on first paint. Don't defer.
-      dispatch(fetchSessions({ dashboardId }));
-      dispatch(fetchLayout({ dashboardId }));
+      const keep = getKeepAliveBrowserIds();
+      // Quiesce + CDP-detach the OUTGOING dashboard's webviews serially BEFORE the store reset
+      // unmounts them all in one frame (the "navigate away kills the app" self-quit). Bounded +
+      // fail-open, so a wedged webview can never block the switch. See dashboardSwitchTeardown.
+      void prepareDashboardSwitch(keep).finally(() => {
+        dispatch(resetLayout({ keepBrowserIds: keep }));
+        // CRITICAL path: these populate the cards the user expects to see on first paint. Don't defer.
+        dispatch(fetchSessions({ dashboardId }));
+        dispatch(fetchLayout({ dashboardId }));
+      });
     }
     const cleanupBrowserHandler = initBrowserCommandHandler();
     // Global broadcasts (spawned browser cards) skip the replay log, so a socket gap loses them; a reconnect refetch is the only way they return.

frontend/src/shared/browserRegistry.ts

@@ -116,6 +116,10 @@ export function getWebview(browserId: string, tabId?: string): BrowserWebview |
   return registry.get(makeKey(browserId, resolvedTabId));
 }
 
+export function getAllBrowserIds(): string[] {
+  return [...new Set([...registry.keys()].map((k) => k.split(':')[0]))];
+}
+
 export function getBrowserWebviews(browserId: string): BrowserWebview[] {
   const out: BrowserWebview[] = [];
   for (const [key, wv] of registry.entries()) {

frontend/src/shared/dashboardSwitchTeardown.ts

@@ -0,0 +1,23 @@
+import { getAllViewOutputIds } from '@/shared/viewWebviewRegistry';
+import { getAllBrowserIds } from '@/shared/browserRegistry';
+import { quiesceViewWebview } from '@/shared/viewTeardown';
+import { detachBrowserCdp } from '@/shared/browserTeardown';
+
+// Switching dashboards clears every card from the store in ONE reducer (resetLayout), so React
+// unmounts all the outgoing app + browser <webview>s in a single frame. Ripping several live GPU
+// surfaces out at once (app previews) or unmounting a browser with its CDP debugger still attached
+// piles up "non-existent mailbox" errors and SIGSEGVs the GPU/browser process, taking the whole app
+// down with no crash dump (the "navigate away and it quits itself" bug). Quiesce + detach the
+// outgoing webviews ONE AT A TIME first, so only trivial surfaces are left to tear down. Bounded per
+// item (the helpers self-cap), fail-open, and keep-alive browsers are skipped so they survive the
+// switch with their session intact.
+export async function prepareDashboardSwitch(keepBrowserIds: string[]): Promise<void> {
+  const keep = new Set(keepBrowserIds);
+  for (const outputId of getAllViewOutputIds()) {
+    await quiesceViewWebview(outputId);
+  }
+  for (const browserId of getAllBrowserIds()) {
+    if (keep.has(browserId)) continue;
+    await detachBrowserCdp(browserId);
+  }
+}

frontend/src/shared/viewWebviewRegistry.ts

@@ -11,6 +11,10 @@ export function registerViewWebview(outputId: string, wv: ViewWebview): void {
   registry.set(outputId, wv);
 }
 
+export function getAllViewOutputIds(): string[] {
+  return [...registry.keys()];
+}
+
 export function unregisterViewWebview(outputId: string): void {
   registry.delete(outputId);
 }