diff -r 7b1b88e27a20 -r 48c4eec2b7e6 wp/wp-includes/blocks/template-part.php
--- a/wp/wp-includes/blocks/template-part.php	Thu Sep 29 08:06:27 2022 +0200
+++ b/wp/wp-includes/blocks/template-part.php	Fri Sep 05 18:40:08 2025 +0200
@@ -8,6 +8,10 @@
 /**
  * Renders the `core/template-part` block on the server.
  *
+ * @since 5.9.0
+ *
+ * @global WP_Embed $wp_embed WordPress Embed object.
+ *
  * @param array $attributes The block attributes.
  *
  * @return string The render.
@@ -18,37 +22,35 @@
 	$template_part_id = null;
 	$content          = null;
 	$area             = WP_TEMPLATE_PART_AREA_UNCATEGORIZED;
+	$theme            = isset( $attributes['theme'] ) ? $attributes['theme'] : get_stylesheet();
 
-	if (
-		isset( $attributes['slug'] ) &&
-		isset( $attributes['theme'] ) &&
-		wp_get_theme()->get_stylesheet() === $attributes['theme']
-	) {
-		$template_part_id    = $attributes['theme'] . '//' . $attributes['slug'];
+	if ( isset( $attributes['slug'] ) && get_stylesheet() === $theme ) {
+		$template_part_id    = $theme . '//' . $attributes['slug'];
 		$template_part_query = new WP_Query(
 			array(
-				'post_type'      => 'wp_template_part',
-				'post_status'    => 'publish',
-				'post_name__in'  => array( $attributes['slug'] ),
-				'tax_query'      => array(
+				'post_type'           => 'wp_template_part',
+				'post_status'         => 'publish',
+				'post_name__in'       => array( $attributes['slug'] ),
+				'tax_query'           => array(
 					array(
 						'taxonomy' => 'wp_theme',
-						'field'    => 'slug',
-						'terms'    => $attributes['theme'],
+						'field'    => 'name',
+						'terms'    => $theme,
 					),
 				),
-				'posts_per_page' => 1,
-				'no_found_rows'  => true,
+				'posts_per_page'      => 1,
+				'no_found_rows'       => true,
+				'lazy_load_term_meta' => false, // Do not lazy load term meta, as template parts only have one term.
 			)
 		);
 		$template_part_post  = $template_part_query->have_posts() ? $template_part_query->next_post() : null;
 		if ( $template_part_post ) {
 			// A published post might already exist if this template part was customized elsewhere
 			// or if it's part of a customized template.
-			$content    = $template_part_post->post_content;
-			$area_terms = get_the_terms( $template_part_post, 'wp_template_part_area' );
-			if ( ! is_wp_error( $area_terms ) && false !== $area_terms ) {
-				$area = $area_terms[0]->name;
+			$block_template = _build_block_template_result_from_post( $template_part_post );
+			$content        = $block_template->content;
+			if ( isset( $block_template->area ) ) {
+				$area = $block_template->area;
 			}
 			/**
 			 * Fires when a block template part is loaded from a template post stored in the database.
@@ -62,18 +64,22 @@
 			 */
 			do_action( 'render_block_core_template_part_post', $template_part_id, $attributes, $template_part_post, $content );
 		} else {
+			$template_part_file_path = '';
 			// Else, if the template part was provided by the active theme,
 			// render the corresponding file content.
-			$parent_theme_folders        = get_block_theme_folders( get_template() );
-			$child_theme_folders         = get_block_theme_folders( get_stylesheet() );
-			$child_theme_part_file_path  = get_theme_file_path( '/' . $child_theme_folders['wp_template_part'] . '/' . $attributes['slug'] . '.html' );
-			$parent_theme_part_file_path = get_theme_file_path( '/' . $parent_theme_folders['wp_template_part'] . '/' . $attributes['slug'] . '.html' );
-			$template_part_file_path     = 0 === validate_file( $attributes['slug'] ) && file_exists( $child_theme_part_file_path ) ? $child_theme_part_file_path : $parent_theme_part_file_path;
-			if ( 0 === validate_file( $attributes['slug'] ) && file_exists( $template_part_file_path ) ) {
-				$content = file_get_contents( $template_part_file_path );
-				$content = is_string( $content ) && '' !== $content
-						? _inject_theme_attribute_in_block_template_content( $content )
-						: '';
+			if ( 0 === validate_file( $attributes['slug'] ) ) {
+				$block_template = get_block_file_template( $template_part_id, 'wp_template_part' );
+
+				$content = $block_template->content;
+				if ( isset( $block_template->area ) ) {
+					$area = $block_template->area;
+				}
+
+				// Needed for the `render_block_core_template_part_file` and `render_block_core_template_part_none` actions below.
+				$block_template_file = _get_block_template_file( 'wp_template_part', $attributes['slug'] );
+				if ( $block_template_file ) {
+					$template_part_file_path = $block_template_file['path'];
+				}
 			}
 
 			if ( '' !== $content && null !== $content ) {
@@ -105,19 +111,18 @@
 
 	// WP_DEBUG_DISPLAY must only be honored when WP_DEBUG. This precedent
 	// is set in `wp_debug_mode()`.
-	$is_debug = defined( 'WP_DEBUG' ) && WP_DEBUG &&
-		defined( 'WP_DEBUG_DISPLAY' ) && WP_DEBUG_DISPLAY;
+	$is_debug = WP_DEBUG && WP_DEBUG_DISPLAY;
 
-	if ( is_null( $content ) && $is_debug ) {
-		if ( ! isset( $attributes['slug'] ) ) {
-			// If there is no slug this is a placeholder and we dont want to return any message.
-			return;
+	if ( is_null( $content ) ) {
+		if ( $is_debug && isset( $attributes['slug'] ) ) {
+			return sprintf(
+				/* translators: %s: Template part slug. */
+				__( 'Template part has been deleted or is unavailable: %s' ),
+				$attributes['slug']
+			);
 		}
-		return sprintf(
-			/* translators: %s: Template part slug. */
-			__( 'Template part has been deleted or is unavailable: %s' ),
-			$attributes['slug']
-		);
+
+		return '';
 	}
 
 	if ( isset( $seen_ids[ $template_part_id ] ) ) {
@@ -127,27 +132,39 @@
 			'';
 	}
 
+	// Look up area definition.
+	$area_definition = null;
+	$defined_areas   = get_allowed_block_template_part_areas();
+	foreach ( $defined_areas as $defined_area ) {
+		if ( $defined_area['area'] === $area ) {
+			$area_definition = $defined_area;
+			break;
+		}
+	}
+
+	// If $area is not allowed, set it back to the uncategorized default.
+	if ( ! $area_definition ) {
+		$area = WP_TEMPLATE_PART_AREA_UNCATEGORIZED;
+	}
+
 	// Run through the actions that are typically taken on the_content.
+	$content                       = shortcode_unautop( $content );
+	$content                       = do_shortcode( $content );
 	$seen_ids[ $template_part_id ] = true;
 	$content                       = do_blocks( $content );
 	unset( $seen_ids[ $template_part_id ] );
 	$content = wptexturize( $content );
 	$content = convert_smilies( $content );
-	$content = shortcode_unautop( $content );
-	$content = wp_filter_content_tags( $content );
-	$content = do_shortcode( $content );
+	$content = wp_filter_content_tags( $content, "template_part_{$area}" );
 
 	// Handle embeds for block template parts.
 	global $wp_embed;
 	$content = $wp_embed->autoembed( $content );
 
-	if ( empty( $attributes['tagName'] ) ) {
-		$defined_areas = get_allowed_block_template_part_areas();
-		$area_tag      = 'div';
-		foreach ( $defined_areas as $defined_area ) {
-			if ( $defined_area['area'] === $area && isset( $defined_area['area_tag'] ) ) {
-				$area_tag = $defined_area['area_tag'];
-			}
+	if ( empty( $attributes['tagName'] ) || tag_escape( $attributes['tagName'] ) !== $attributes['tagName'] ) {
+		$area_tag = 'div';
+		if ( $area_definition && isset( $area_definition['area_tag'] ) ) {
+			$area_tag = $area_definition['area_tag'];
 		}
 		$html_tag = $area_tag;
 	} else {
@@ -159,23 +176,38 @@
 }
 
 /**
- * Returns an array of variation objects for the template part block.
+ * Returns an array of area variation objects for the template part block.
+ *
+ * @since 6.1.0
+ *
+ * @param array $instance_variations The variations for instances.
  *
  * @return array Array containing the block variation objects.
  */
-function build_template_part_block_variations() {
+function build_template_part_block_area_variations( $instance_variations ) {
 	$variations    = array();
 	$defined_areas = get_allowed_block_template_part_areas();
+
 	foreach ( $defined_areas as $area ) {
 		if ( 'uncategorized' !== $area['area'] ) {
+			$has_instance_for_area = false;
+			foreach ( $instance_variations as $variation ) {
+				if ( $variation['attributes']['area'] === $area['area'] ) {
+					$has_instance_for_area = true;
+					break;
+				}
+			}
+
+			$scope = $has_instance_for_area ? array() : array( 'inserter' );
+
 			$variations[] = array(
-				'name'        => $area['area'],
+				'name'        => 'area_' . $area['area'],
 				'title'       => $area['label'],
 				'description' => $area['description'],
 				'attributes'  => array(
 					'area' => $area['area'],
 				),
-				'scope'       => array( 'inserter' ),
+				'scope'       => $scope,
 				'icon'        => $area['icon'],
 			);
 		}
@@ -184,14 +216,85 @@
 }
 
 /**
+ * Returns an array of instance variation objects for the template part block
+ *
+ * @since 6.1.0
+ *
+ * @return array Array containing the block variation objects.
+ */
+function build_template_part_block_instance_variations() {
+	// Block themes are unavailable during installation.
+	if ( wp_installing() ) {
+		return array();
+	}
+
+	if ( ! current_theme_supports( 'block-templates' ) && ! current_theme_supports( 'block-template-parts' ) ) {
+		return array();
+	}
+
+	$variations     = array();
+	$template_parts = get_block_templates(
+		array(
+			'post_type' => 'wp_template_part',
+		),
+		'wp_template_part'
+	);
+
+	$defined_areas = get_allowed_block_template_part_areas();
+	$icon_by_area  = array_combine( array_column( $defined_areas, 'area' ), array_column( $defined_areas, 'icon' ) );
+
+	foreach ( $template_parts as $template_part ) {
+		$variations[] = array(
+			'name'        => 'instance_' . sanitize_title( $template_part->slug ),
+			'title'       => $template_part->title,
+			// If there's no description for the template part don't show the
+			// block description. This is a bit hacky, but prevent the fallback
+			// by using a non-breaking space so that the value of description
+			// isn't falsey.
+			'description' => $template_part->description || ' ',
+			'attributes'  => array(
+				'slug'  => $template_part->slug,
+				'theme' => $template_part->theme,
+				'area'  => $template_part->area,
+			),
+			'scope'       => array( 'inserter' ),
+			'icon'        => isset( $icon_by_area[ $template_part->area ] ) ? $icon_by_area[ $template_part->area ] : null,
+			'example'     => array(
+				'attributes' => array(
+					'slug'  => $template_part->slug,
+					'theme' => $template_part->theme,
+					'area'  => $template_part->area,
+				),
+			),
+		);
+	}
+	return $variations;
+}
+
+/**
+ * Returns an array of all template part block variations.
+ *
+ * @since 5.9.0
+ *
+ * @return array Array containing the block variation objects.
+ */
+function build_template_part_block_variations() {
+	$instance_variations = build_template_part_block_instance_variations();
+	$area_variations     = build_template_part_block_area_variations( $instance_variations );
+	return array_merge( $area_variations, $instance_variations );
+}
+
+/**
  * Registers the `core/template-part` block on the server.
+ *
+ * @since 5.9.0
  */
 function register_block_core_template_part() {
 	register_block_type_from_metadata(
 		__DIR__ . '/template-part',
 		array(
-			'render_callback' => 'render_block_core_template_part',
-			'variations'      => build_template_part_block_variations(),
+			'render_callback'    => 'render_block_core_template_part',
+			'variation_callback' => 'build_template_part_block_variations',
 		)
 	);
 }