Use the reading-list app from example 14. Start it at http://localhost:8080.
In this test folder, follow the official Playwright setup:
https://playwright.dev/docs/intro
For an existing Node project: npm install -D @playwright/test
Install its Chromium browser with: npx playwright install chromium
Run: npx playwright test reading-list.spec.js --workers=1
These commands require network/package installation on your computer.
This Playwright suite is supplied but was not executed during preparation.

To check mutation detection in a DISPOSABLE app copy:
1. Remove the list.appendChild(item) line marked APPEND_POINT. The add-item
   test should fail because no item becomes visible. Restore it.
2. Remove the localStorage.setItem line marked SAVE_POINT. The reload test
   should fail because the item is not restored. Restore it.
The included Node verification record actually executed both mutations in a
simulated DOM. That is separate from a real Playwright/browser run.