diff -r 7b1b88e27a20 -r 48c4eec2b7e6 wp/wp-admin/site-editor.php
--- a/wp/wp-admin/site-editor.php	Thu Sep 29 08:06:27 2022 +0200
+++ b/wp/wp-admin/site-editor.php	Fri Sep 05 18:40:08 2025 +0200
@@ -6,7 +6,7 @@
  * @subpackage Administration
  */
 
-global $post, $editor_styles;
+global $editor_styles;
 
 /** WordPress Administration Bootstrap */
 require_once __DIR__ . '/admin.php';
@@ -19,29 +19,23 @@
 	);
 }
 
-if ( ! wp_is_block_theme() ) {
-	wp_die( __( 'The theme you are currently using is not compatible with Full Site Editing.' ) );
-}
+$is_template_part        = isset( $_GET['postType'] ) && 'wp_template_part' === sanitize_key( $_GET['postType'] );
+$is_template_part_path   = isset( $_GET['path'] ) && 'wp_template_partall' === sanitize_key( $_GET['path'] );
+$is_template_part_editor = $is_template_part || $is_template_part_path;
+$is_patterns             = isset( $_GET['postType'] ) && 'wp_block' === sanitize_key( $_GET['postType'] );
+$is_patterns_path        = isset( $_GET['path'] ) && 'patterns' === sanitize_key( $_GET['path'] );
+$is_patterns_editor      = $is_patterns || $is_patterns_path;
 
-/**
- * Do a server-side redirection if missing `postType` and `postId`
- * query args when visiting Site Editor.
- */
-$home_template = _resolve_home_block_template();
-if ( $home_template && empty( $_GET['postType'] ) && empty( $_GET['postId'] ) ) {
-	if ( ! empty( $_GET['styles'] ) ) {
-		$home_template['styles'] = sanitize_key( $_GET['styles'] );
+if ( ! wp_is_block_theme() ) {
+	if ( ! current_theme_supports( 'block-template-parts' ) && $is_template_part_editor ) {
+		wp_die( __( 'The theme you are currently using is not compatible with the Site Editor.' ) );
+	} elseif ( ! $is_patterns_editor && ! $is_template_part_editor ) {
+		wp_die( __( 'The theme you are currently using is not compatible with the Site Editor.' ) );
 	}
-	$redirect_url = add_query_arg(
-		$home_template,
-		admin_url( 'site-editor.php' )
-	);
-	wp_safe_redirect( $redirect_url );
-	exit;
 }
 
 // Used in the HTML title tag.
-$title       = __( 'Editor (beta)' );
+$title       = _x( 'Editor', 'site editor title tag' );
 $parent_file = 'themes.php';
 
 // Flag that we're loading the block editor.
@@ -51,7 +45,7 @@
 // Default to is-fullscreen-mode to avoid jumps in the UI.
 add_filter(
 	'admin_body_class',
-	static function( $classes ) {
+	static function ( $classes ) {
 		return "$classes is-fullscreen-mode";
 	}
 );
@@ -64,19 +58,20 @@
 
 $block_editor_context = new WP_Block_Editor_Context( array( 'name' => 'core/edit-site' ) );
 $custom_settings      = array(
-	'siteUrl'                  => site_url(),
-	'postsPerPage'             => get_option( 'posts_per_page' ),
-	'styles'                   => get_block_editor_theme_styles(),
-	'defaultTemplateTypes'     => $indexed_template_types,
-	'defaultTemplatePartAreas' => get_allowed_block_template_part_areas(),
-	'__unstableHomeTemplate'   => $home_template,
+	'siteUrl'                   => site_url(),
+	'postsPerPage'              => get_option( 'posts_per_page' ),
+	'styles'                    => get_block_editor_theme_styles(),
+	'defaultTemplateTypes'      => $indexed_template_types,
+	'defaultTemplatePartAreas'  => get_allowed_block_template_part_areas(),
+	'supportsLayout'            => wp_theme_has_theme_json(),
+	'supportsTemplatePartsMode' => ! wp_is_block_theme() && current_theme_supports( 'block-template-parts' ),
 );
 
 // Add additional back-compat patterns registered by `current_screen` et al.
 $custom_settings['__experimentalAdditionalBlockPatterns']          = WP_Block_Patterns_Registry::get_instance()->get_all_registered( true );
 $custom_settings['__experimentalAdditionalBlockPatternCategories'] = WP_Block_Pattern_Categories_Registry::get_instance()->get_all_registered( true );
 
-$editor_settings      = get_block_editor_settings( $custom_settings, $block_editor_context );
+$editor_settings = get_block_editor_settings( $custom_settings, $block_editor_context );
 
 if ( isset( $_GET['postType'] ) && ! isset( $_GET['postId'] ) ) {
 	$post_type = get_post_type_object( $_GET['postType'] );
@@ -86,8 +81,13 @@
 }
 
 $active_global_styles_id = WP_Theme_JSON_Resolver::get_user_global_styles_post_id();
-$active_theme            = wp_get_theme()->get_stylesheet();
-$preload_paths           = array(
+$active_theme            = get_stylesheet();
+
+$navigation_rest_route = rest_get_route_for_post_type_items(
+	'wp_navigation'
+);
+
+$preload_paths = array(
 	array( '/wp/v2/media', 'OPTIONS' ),
 	'/wp/v2/types?context=view',
 	'/wp/v2/types/wp_template?context=edit',
@@ -98,6 +98,22 @@
 	'/wp/v2/global-styles/' . $active_global_styles_id . '?context=edit',
 	'/wp/v2/global-styles/' . $active_global_styles_id,
 	'/wp/v2/global-styles/themes/' . $active_theme,
+	array( $navigation_rest_route, 'OPTIONS' ),
+	array(
+		add_query_arg(
+			array(
+				'context'   => 'edit',
+				'per_page'  => 100,
+				'order'     => 'desc',
+				'orderby'   => 'date',
+				// array indices are required to avoid query being encoded and not matching in cache.
+				'status[0]' => 'publish',
+				'status[1]' => 'draft',
+			),
+			$navigation_rest_route
+		),
+		'GET',
+	),
 );
 
 block_editor_rest_api_preload( $preload_paths, $block_editor_context );
@@ -120,7 +136,7 @@
 
 wp_add_inline_script(
 	'wp-blocks',
-	sprintf( 'wp.blocks.setCategories( %s );', wp_json_encode( get_block_categories( $post ) ) ),
+	sprintf( 'wp.blocks.setCategories( %s );', wp_json_encode( isset( $editor_settings['blockCategories'] ) ? $editor_settings['blockCategories'] : array() ) ),
 	'after'
 );
 
@@ -131,7 +147,7 @@
 wp_enqueue_media();
 
 if (
-	current_theme_supports( 'wp-block-styles' ) ||
+	current_theme_supports( 'wp-block-styles' ) &&
 	( ! is_array( $editor_styles ) || count( $editor_styles ) === 0 )
 ) {
 	wp_enqueue_style( 'wp-block-library-theme' );
@@ -143,7 +159,31 @@
 require_once ABSPATH . 'wp-admin/admin-header.php';
 ?>
 
-<div id="site-editor" class="edit-site"></div>
+<div class="edit-site" id="site-editor">
+	<?php // JavaScript is disabled. ?>
+	<div class="wrap hide-if-js site-editor-no-js">
+		<h1 class="wp-heading-inline"><?php _e( 'Edit site' ); ?></h1>
+		<?php
+		/**
+		 * Filters the message displayed in the site editor interface when JavaScript is
+		 * not enabled in the browser.
+		 *
+		 * @since 6.3.0
+		 *
+		 * @param string  $message The message being displayed.
+		 * @param WP_Post $post    The post being edited.
+		 */
+		$message = apply_filters( 'site_editor_no_javascript_message', __( 'The site editor requires JavaScript. Please enable JavaScript in your browser settings.' ), $post );
+		wp_admin_notice(
+			$message,
+			array(
+				'type'               => 'error',
+				'additional_classes' => array( 'hide-if-js' ),
+			)
+		);
+		?>
+	</div>
+</div>
 
 <?php