What?

Optimizes the revisions REST API endpoint and client-side queries to avoid fetching expensive rendered fields (content.rendered, title.rendered, excerpt.rendered) when only raw data is needed.

Why?

The speedup is significant: from 5-6 seconds to 50-60 ms for 20 revisions!

The REST API _fields documentation states that nested fields are supported using dot notation. However, the core WP_REST_Revisions_Controller uses in_array() which doesn't match nested keys like content.raw — so clients either get both raw and rendered, or neither.

Several other controllers already use rest_is_field_included() for raw/rendered sub-fields:

• WP_REST_Posts_Controller
• WP_REST_Templates_Controller
• WP_REST_Menu_Items_Controller
• WP_REST_Global_Styles_Controller
• WP_REST_Themes_Controller

How?

PHP: Override revisions controller (WordPress 7.0 compat)

• Adds Gutenberg_REST_Revisions_Controller extending WP_REST_Revisions_Controller
• Replaces in_array() checks with rest_is_field_included() for content, title, excerpt, and guid fields
• Registers the override via register_post_type_args filter, following the same pattern as the autosaves controller override

JS: Request only needed sub-fields

• Updates getCurrentRevision, getPreviousRevision, the revisions slider, useEntityProp, and restoreRevision to use _fields=id,date,author,meta,title.raw,excerpt.raw,content.raw
• All callers use the same query, ensuring a single shared API request

Testing Instructions

1. Open a post with multiple revisions
2. Open the revisions panel in the document sidebar
3. Open browser DevTools Network tab
4. Verify the revisions API request includes _fields=id%2Cdate%2Cauthor%2Cmeta%2Ctitle.raw%2Cexcerpt.raw%2Ccontent.raw
5. Verify the response contains content.raw but NOT content.rendered
6. Verify revision diffing works correctly (scrub through revisions, compare content)
7. Verify restoring a revision still works

Testing Instructions for Keyboard

1. Open a post with revisions using keyboard navigation
2. Tab to the revisions slider in the document sidebar
3. Use arrow keys to scrub through revisions
4. Verify revision content updates correctly