Add expiring panel auth sessions

src/App.test.tsx

@@ -1,6 +1,6 @@
 import { render, screen, within } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
-import { describe, expect, it } from 'vitest';
+import { beforeEach, describe, expect, it } from 'vitest';
 import App from './App';
 
 async function loginIntoPanel(user: ReturnType<typeof userEvent.setup>) {
@@ -9,6 +9,10 @@ async function loginIntoPanel(user: ReturnType<typeof userEvent.setup>) {
   await user.click(screen.getByRole('button', { name: /open panel/i }));
 }
 
+beforeEach(() => {
+  window.sessionStorage.clear();
+});
+
 describe('App login gate', () => {
   it('rejects wrong hardcoded credentials and keeps the panel locked', async () => {
     const user = userEvent.setup();
@@ -32,6 +36,20 @@ describe('App login gate', () => {
     expect(screen.getByRole('heading', { name: /3proxy ui/i })).toBeInTheDocument();
   });
 
+  it('restores the panel session from sessionStorage after a remount', async () => {
+    const user = userEvent.setup();
+    const firstRender = render(<App />);
+
+    await loginIntoPanel(user);
+    expect(screen.getByRole('navigation', { name: /primary/i })).toBeInTheDocument();
+
+    firstRender.unmount();
+    render(<App />);
+
+    expect(screen.getByRole('navigation', { name: /primary/i })).toBeInTheDocument();
+    expect(screen.queryByRole('button', { name: /open panel/i })).not.toBeInTheDocument();
+  });
+
   it('opens add-user flow in a modal and closes it on escape', async () => {
     const user = userEvent.setup();
     render(<App />);