This commit: (#50563)

- adds an `_edit_link` property to `wp_global_styles`, `wp_template`, and `wp_template-part` custom post type schemata via filter
- uses the `_edit_link` value to create an edit link via the `get_edit_post_link` hook

lib/compat/wordpress-6.3/link-template.php

@@ -0,0 +1,34 @@
+<?php
+/**
+ * Overrides Core's wp-includes/link-template.php for WP 6.3.
+ *
+ * @package gutenberg
+ */
+
+/**
+ * Updates the post edit link using the `_edit_link` property in wp_global_styles`, `wp_template`,
+ * and `wp_template_part` custom post types.
+ *
+ * `_edit_link` for these custom post types is added by `gutenberg_update_templates_template_parts_rest_controller()`
+ * in lib/compat/wordpress-6.3/rest-api.php.
+ *
+ * This functionality has already been ported to Core. See https://github.com/WordPress/gutenberg/issues/48065
+ * The following hook is a modified version that passes only 2 arguments to `sprintf()` to be compatible with WP <= 6.2.
+ *
+ * @param string $link    The edit link.
+ * @param int    $post_id Post ID.
+ * @return string|null The edit post link for the given post. Null if the post type does not exist
+ *                     or does not allow an editing UI.
+ */
+function gutenberg_update_get_edit_post_link( $link, $post_id ) {
+	$post = get_post( $post_id );
+
+	if ( 'wp_template' === $post->post_type || 'wp_template_part' === $post->post_type ) {
+		$post_type_object = get_post_type_object( $post->post_type );
+		$slug             = urlencode( get_stylesheet() . '//' . $post->post_name );
+		$link             = admin_url( sprintf( $post_type_object->_edit_link, $slug ) );
+	}
+	return $link;
+}
+
+add_filter( 'get_edit_post_link', 'gutenberg_update_get_edit_post_link', 10, 2 );

lib/compat/wordpress-6.3/rest-api.php

@@ -15,21 +15,35 @@ function gutenberg_register_rest_pattern_directory() {
 add_action( 'rest_api_init', 'gutenberg_register_rest_pattern_directory' );
 
 /**
- * Update `wp_template` and `wp_template-part` post types to use
- * Gutenberg's REST controller.
+ * Updates `wp_template` and `wp_template_part` post types to use
+ * Gutenberg's REST controllers
+ *
+ * Adds `_edit_link` to the `wp_global_styles`, `wp_template`,
+ * and `wp_template_part` post type schemata. See https://github.com/WordPress/gutenberg/issues/48065
  *
  * @param array  $args Array of arguments for registering a post type.
  * @param string $post_type Post type key.
  */
 function gutenberg_update_templates_template_parts_rest_controller( $args, $post_type ) {
 	if ( in_array( $post_type, array( 'wp_template', 'wp_template_part' ), true ) ) {
+		$template_edit_link            = 'site-editor.php?' . build_query(
+			array(
+				'postType' => $post_type,
+				'postId'   => '%s',
+				'canvas'   => 'edit',
+			)
+		);
+		$args['_edit_link']            = $template_edit_link;
 		$args['rest_controller_class'] = 'Gutenberg_REST_Templates_Controller_6_3';
 	}
+
+	if ( in_array( $post_type, array( 'wp_global_styles' ), true ) ) {
+		$args['_edit_link'] = '/site-editor.php?canvas=edit';
+	}
 	return $args;
 }
 add_filter( 'register_post_type_args', 'gutenberg_update_templates_template_parts_rest_controller', 10, 2 );
 
-
 /**
  * Registers the Global Styles Revisions REST API routes.
  */

lib/load.php

@@ -50,6 +50,7 @@ function gutenberg_is_experiment_enabled( $name ) {
 	require_once __DIR__ . '/compat/wordpress-6.3/rest-api.php';
 	require_once __DIR__ . '/compat/wordpress-6.3/theme-previews.php';
 	require_once __DIR__ . '/compat/wordpress-6.3/navigation-block-preloading.php';
+	require_once __DIR__ . '/compat/wordpress-6.3/link-template.php';
 
 	// Experimental.
 	if ( ! class_exists( 'WP_Rest_Customizer_Nonces' ) ) {