wp_redirect('/') after login breaks WordPress Multisite subdirectory installs #963

Checklist

• I have looked into the Readme and the documentation, and have not found a suitable solution or answer.
• I have searched the issues and have not found a suitable solution or answer.
• I have searched the Auth0 Community forums and have not found a suitable solution or answer.
• I agree to the terms within the Auth0 Code of Conduct.

Description

Several code paths hardcode wp_redirect('/') instead of resolving the current site's URL. On a Multisite subdirectory install, an absolute / always resolves to the network's root site, not the subsite the user is actually logging into. onLogout() gets this right (passes get_site_url(), which is subsite-aware) but the login/exchange paths don't.

Reproduction

1. Set up WordPress Multisite in subdirectory mode with at least one non-root subsite.
2. Configure and activate the plugin network-wide.
3. Log in on example.com/subsite-a/wp-login.php.
4. Observe the redirect lands on example.com/ (network root) instead of example.com/subsite-a/.

Additional context

// onLogin() success, ~539 / error, ~546 / already-authenticated, ~551
wp_redirect('/');
// onExchangeFailed(), ~562
wp_redirect('/');

Related: #935, closed as stale without a confirmed root cause. Suggested fix: use admin_url() or get_site_url() in all four locations, matching onLogout().

wp-auth0 version

5.6.1

WordPress version

7.1

PHP version

8.4