Regression checks use the plugin's real PHP and template JavaScript, WordPress core's block/shortcode parsers and HTML API, and an isolated database/cache boundary. They do not load a live WordPress installation or change a site's database.

Extract WordPress 6.9 into a temporary directory and install `jsdom` into a separate temporary dependencies directory. Run:

```text
php tests/realign-regression.php /path/to/wordpress
php tests/realign-regression.php /path/to/wordpress --regex
node tests/realign-ui.cjs /path/to/test-dependencies /path/to/wordpress
```

The UI check uses the jQuery version shipped with that WordPress core. The second PHP run exercises the legacy HTML regex fallback. Database concurrency checks simulate unique-key locking and conditional writes; testing against a live MySQL/WordPress installation remains a separate integration check.

Exclude this tests directory from installable plugin archives.