VIP MU plugins v20260721.1

View Pull Request: https://github.com/Automattic/vip-go-mu-plugins/pull/7126

Fixed

• Fixed admin_url() resolving to the production hostname on sandboxes, which caused cross-origin request failures for AJAX calls using admin-ajax.php.
• Real-Time Collaboration: Preserved collaborators’ unsaved content and post meta when another user saves, prevented redundant empty autosave revisions, and restored undo and redo when plugins with incompatible meta boxes disable collaboration.
• Real-Time Collaboration: Disabled Quick Edit for posts with active collaborative sessions and improved remote cursor and selection positioning while resizing the browser window.

Changed

• Real-Time Collaboration: Updated the bundled Gutenberg integration from the 0.2-20260706-pr79021 build based on Gutenberg 23.5.0 to the 0.2-20260720-pr79021 build based on the July 20 Gutenberg trunk snapshot. The VIP RTC plugin remains at v0.3.2.
• Real-Time Collaboration: Added independent controls for collaborator join, leave, and post-update notifications, and avoided synchronous CRDT updates while editing alone to reduce typing latency outside active collaboration.
• Updated the wp-parsely submodule (used for local development environments) to version 3.23.4.