feat(toggleMode): restore file preview tab when returning from terminal

When pressing cmd+j to switch between AI/terminal mode, the previously
active file preview tab is now saved and restored. This allows users
to view a file, switch to terminal, run commands, then switch back and
have the same file preview re-opened automatically.

Added preTerminalFileTabIdRef to UILayoutContext to track the active
file tab before switching to terminal mode. Updated toggleInputMode
to save/restore this state.

src/__tests__/renderer/hooks/useMainKeyboardHandler.test.ts

@@ -460,6 +460,43 @@ describe('useMainKeyboardHandler', () => {
 			expect(mockReopenUnifiedClosedTab).toHaveBeenCalledWith(mockActiveSession);
 			expect(mockSetSessions).toHaveBeenCalled();
 		});
+
+		it('should allow toggleMode shortcut (Cmd+J) when only overlays are open', () => {
+			const { result } = renderHook(() => useMainKeyboardHandler());
+
+			const mockToggleInputMode = vi.fn();
+			const mockActiveSession = {
+				id: 'test-session',
+				name: 'Test',
+				inputMode: 'ai',
+				aiTabs: [{ id: 'tab-1', name: 'Tab 1', logs: [] }],
+				activeTabId: 'tab-1',
+				filePreviewTabs: [{ id: 'file-tab-1', path: '/test.ts' }],
+				activeFileTabId: 'file-tab-1', // File preview is active
+			};
+
+			result.current.keyboardHandlerRef.current = createMockContext({
+				hasOpenLayers: () => true, // Overlay is open (file preview)
+				hasOpenModal: () => false, // But no true modal
+				isShortcut: (_e: KeyboardEvent, actionId: string) => actionId === 'toggleMode',
+				activeSessionId: 'test-session',
+				activeSession: mockActiveSession,
+				toggleInputMode: mockToggleInputMode,
+			});
+
+			act(() => {
+				window.dispatchEvent(
+					new KeyboardEvent('keydown', {
+						key: 'j',
+						metaKey: true,
+						bubbles: true,
+					})
+				);
+			});
+
+			// Cmd+J should toggle mode even when file preview overlay is open
+			expect(mockToggleInputMode).toHaveBeenCalled();
+		});
 	});
 
 	describe('navigation handlers delegation', () => {

src/renderer/App.tsx

@@ -757,6 +757,8 @@ function MaestroConsoleInner() {
 	const { showUnreadOnly, setShowUnreadOnly } = useUILayout();
 	// Track the active tab ID before entering unread filter mode, so we can restore it when exiting
 	const { preFilterActiveTabIdRef } = useUILayout();
+	// Track the active file tab ID before switching to terminal mode, so we can restore it when returning to AI mode
+	const { preTerminalFileTabIdRef } = useUILayout();
 
 	// File Explorer State
 	const [filePreviewLoading, setFilePreviewLoading] = useState<{
@@ -9799,14 +9801,27 @@ You are taking over this conversation. Based on the context above, provide a bri
 			prev.map((s) => {
 				if (s.id !== activeSessionId) return s;
 				const newMode = s.inputMode === 'ai' ? 'terminal' : 'ai';
-				// Clear file preview when switching to terminal mode
-				// This ensures cmd+j from file preview goes directly to terminal
-				const clearFileTab = newMode === 'terminal';
-				return {
-					...s,
-					inputMode: newMode,
-					...(clearFileTab && { activeFileTabId: null }),
-				};
+
+				if (newMode === 'terminal') {
+					// Switching to terminal mode: save current file tab (if any) and clear it
+					preTerminalFileTabIdRef.current = s.activeFileTabId;
+					return {
+						...s,
+						inputMode: newMode,
+						activeFileTabId: null,
+					};
+				} else {
+					// Switching to AI mode: restore previous file tab if it still exists
+					const savedFileTabId = preTerminalFileTabIdRef.current;
+					const fileTabStillExists =
+						savedFileTabId && s.filePreviewTabs?.some((t) => t.id === savedFileTabId);
+					preTerminalFileTabIdRef.current = null;
+					return {
+						...s,
+						inputMode: newMode,
+						...(fileTabStillExists && { activeFileTabId: savedFileTabId }),
+					};
+				}
 			})
 		);
 		// Close any open dropdowns when switching modes

src/renderer/contexts/UILayoutContext.tsx

@@ -50,6 +50,8 @@ export interface UILayoutContextValue {
 	setShowUnreadOnly: React.Dispatch<React.SetStateAction<boolean>>;
 	toggleShowUnreadOnly: () => void;
 	preFilterActiveTabIdRef: React.MutableRefObject<string | null>;
+	// Track the active file tab ID before switching to terminal mode, so we can restore it when returning to AI mode
+	preTerminalFileTabIdRef: React.MutableRefObject<string | null>;
 
 	// Session sidebar selection
 	selectedSidebarIndex: number;
@@ -128,6 +130,8 @@ export function UILayoutProvider({ children }: UILayoutProviderProps) {
 	const [showUnreadOnly, setShowUnreadOnly] = useState(false);
 	// Track the active tab ID before entering unread filter mode, so we can restore it when exiting
 	const preFilterActiveTabIdRef = useRef<string | null>(null);
+	// Track the active file tab ID before switching to terminal mode, so we can restore it when returning to AI mode
+	const preTerminalFileTabIdRef = useRef<string | null>(null);
 
 	// Session sidebar selection
 	const [selectedSidebarIndex, setSelectedSidebarIndex] = useState(0);
@@ -206,6 +210,7 @@ export function UILayoutProvider({ children }: UILayoutProviderProps) {
 			setShowUnreadOnly,
 			toggleShowUnreadOnly,
 			preFilterActiveTabIdRef,
+			preTerminalFileTabIdRef,
 
 			// Session sidebar selection
 			selectedSidebarIndex,