Gutenberg compatibility for dynamic metaboxes

Description

One of our favorite, simple and intuitive features is the ability to update metaboxes dynamically whilst editing a post. For example, metaboxes will hide or show depending on their location rules when changing the post template, format, parent and other post attributes.

To do this, we use JS to detect "changes" to the post attributes. Once a change is detected, we send an AJAX request with the current "post" information and use the returned JSON to hide, show or update the metaboxes. We also update the "Show on Screen" checkbox elements to match the visible metaboxes.

Issues

• Existing jQuery event listeners are not compatible with Gutenberg

Questions

• How do we listen for changes to the following post attributes?
  page_template
  page_parent
  post_format
  post_terms
• How do we get these values on initial page load?
• How do we get these values on change?
• How can we hide and show metaboxes? Is CSS ok for this?
• How can we update the "Show on Screen" check boxes to match the visible metaboxes?

Start by tracing the existing jQuery event listeners and AJAX flow for dynamic metaboxes. Identify how Gutenberg exposes page_template, page_parent, post_format, and post_terms on initial load and when they change. Done means metabox visibility and the “Show on Screen” checkboxes stay synchronized in Gutenberg.