feat(03-01): wire overlay into App and add context event listener

- Initialize context system on app mount before notification listeners
- Render ContextSwitchOverlay as first child in ErrorBoundary
- Add context:onChanged listener to sync renderer state on external context switches
- Snapshot validation already implemented in contextSlice (validateSnapshot function)

src/renderer/App.tsx

@@ -1,9 +1,10 @@
 import React, { useEffect } from 'react';
 
+import { ContextSwitchOverlay } from './components/common/ContextSwitchOverlay';
 import { ErrorBoundary } from './components/common/ErrorBoundary';
 import { TabbedLayout } from './components/layout/TabbedLayout';
 import { useTheme } from './hooks/useTheme';
-import { initializeNotificationListeners } from './store';
+import { initializeNotificationListeners, useStore } from './store';
 
 export const App = (): React.JSX.Element => {
   // Initialize theme on app load
@@ -18,6 +19,11 @@ export const App = (): React.JSX.Element => {
     }
   }, []);
 
+  // Initialize context system (before notification listeners)
+  useEffect(() => {
+    void useStore.getState().initializeContextSystem();
+  }, []);
+
   // Initialize IPC event listeners (notifications, file changes)
   useEffect(() => {
     const cleanup = initializeNotificationListeners();
@@ -26,6 +32,7 @@ export const App = (): React.JSX.Element => {
 
   return (
     <ErrorBoundary>
+      <ContextSwitchOverlay />
       <TabbedLayout />
     </ErrorBoundary>
   );

src/renderer/store/index.ts

@@ -302,6 +302,22 @@ export function initializeNotificationListeners(): () => void {
     }
   }
 
+  // Listen for context changes from main process (e.g., SSH disconnect)
+  if (window.electronAPI.context?.onChanged) {
+    const cleanup = window.electronAPI.context.onChanged((_event: unknown, data: unknown) => {
+      const { id } = data as { id: string };
+      const currentContextId = useStore.getState().activeContextId;
+      if (id !== currentContextId) {
+        // Main process switched context externally (e.g., SSH disconnect)
+        // Trigger renderer-side context switch to sync state
+        void useStore.getState().switchContext(id);
+      }
+    });
+    if (typeof cleanup === 'function') {
+      cleanupFns.push(cleanup);
+    }
+  }
+
   // Return cleanup function
   return () => {
     for (const timer of pendingSessionRefreshTimers.values()) {