Incorporating foundation of "Notes" feature

src/wp-admin/includes/class-wp-comments-list-table.php

@@ -151,6 +151,7 @@ public function prepare_items() {
 			'order'                     => $order,
 			'post_type'                 => $post_type,
 			'update_comment_post_cache' => true,
+			'type__not_in'              => array( 'note' ),
 		);
 
 		/**

src/wp-admin/includes/comment.php

@@ -157,7 +157,7 @@ function get_pending_comments_num( $post_id ) {
 	$post_id_array = array_map( 'intval', $post_id_array );
 	$post_id_in    = "'" . implode( "', '", $post_id_array ) . "'";
 
-	$pending = $wpdb->get_results( "SELECT comment_post_ID, COUNT(comment_ID) as num_comments FROM $wpdb->comments WHERE comment_post_ID IN ( $post_id_in ) AND comment_approved = '0' GROUP BY comment_post_ID", ARRAY_A );
+	$pending = $wpdb->get_results( "SELECT comment_post_ID, COUNT(comment_ID) as num_comments FROM $wpdb->comments WHERE comment_post_ID IN ( $post_id_in ) AND comment_approved = '0' AND comment_type != 'note' GROUP BY comment_post_ID", ARRAY_A );
 
 	if ( $single ) {
 		if ( empty( $pending ) ) {

src/wp-includes/comment.php

@@ -417,6 +417,7 @@ function get_comment_count( $post_id = 0 ) {
 		'count'                     => true,
 		'update_comment_meta_cache' => false,
 		'orderby'                   => 'none',
+		'type__not_in'              => array( 'note' ),
 	);
 	if ( $post_id > 0 ) {
 		$args['post_id'] = $post_id;
@@ -714,6 +715,11 @@ function wp_allow_comment( $commentdata, $wp_error = false ) {
 
 	$dupe_id = $wpdb->get_var( $dupe );
 
+	// Allow duplicate notes for resolution purposes.
+	if ( isset( $commentdata['comment_type'] ) && 'note' === $commentdata['comment_type'] ) {
+		$dupe_id = false;
+	}
+
 	/**
 	 * Filters the ID, if any, of the duplicate comment found when creating a new comment.
 	 *
@@ -4103,3 +4109,27 @@ function _wp_check_for_scheduled_update_comment_type() {
 		wp_schedule_single_event( time() + MINUTE_IN_SECONDS, 'wp_update_comment_type_batch' );
 	}
 }
+
+/**
+ * Register initial note status meta.
+ *
+ * @since 6.9.0
+ */
+function wp_create_initial_comment_meta() {
+	register_meta(
+		'comment',
+		'_wp_note_status',
+		array(
+			'type'          => 'string',
+			'description'   => __( 'Note resolution status' ),
+			'single'        => true,
+			'show_in_rest'  => array(
+				'schema' => array(
+					'type' => 'string',
+					'enum' => array( 'resolved', 'reopen' ),
+				),
+			),
+		)
+	);
+}
+add_action( 'init', 'wp_create_initial_comment_meta' );

src/wp-includes/link-template.php

@@ -4343,9 +4343,11 @@ function is_avatar_comment_type( $comment_type ) {
 	 *
 	 * @since 3.0.0
 	 *
-	 * @param array $types An array of content types. Default only contains 'comment'.
+	 * @since 6.9.0 The 'note' comment type was added.
+	 *
+	 * @param array $types An array of content types. Default contains 'comment' and 'note'.
 	 */
-	$allowed_comment_types = apply_filters( 'get_avatar_comment_types', array( 'comment' ) );
+	$allowed_comment_types = apply_filters( 'get_avatar_comment_types', array( 'comment', 'note' ) );
 
 	return in_array( $comment_type, (array) $allowed_comment_types, true );
 }

src/wp-includes/post.php

@@ -37,7 +37,18 @@ function create_initial_post_types() {
 			'rewrite'               => false,
 			'query_var'             => false,
 			'delete_with_user'      => true,
-			'supports'              => array( 'title', 'editor', 'author', 'thumbnail', 'excerpt', 'trackbacks', 'custom-fields', 'comments', 'revisions', 'post-formats' ),
+			'supports'              => array(
+				'title',
+				'editor' => array( 'notes' => true ),
+				'author',
+				'thumbnail',
+				'excerpt',
+				'trackbacks',
+				'custom-fields',
+				'comments',
+				'revisions',
+				'post-formats',
+			),
 			'show_in_rest'          => true,
 			'rest_base'             => 'posts',
 			'rest_controller_class' => 'WP_REST_Posts_Controller',
@@ -62,7 +73,16 @@ function create_initial_post_types() {
 			'rewrite'               => false,
 			'query_var'             => false,
 			'delete_with_user'      => true,
-			'supports'              => array( 'title', 'editor', 'author', 'thumbnail', 'page-attributes', 'custom-fields', 'comments', 'revisions' ),
+			'supports'              => array(
+				'title',
+				'editor' => array( 'notes' => true ),
+				'author',
+				'thumbnail',
+				'page-attributes',
+				'custom-fields',
+				'comments',
+				'revisions',
+			),
 			'show_in_rest'          => true,
 			'rest_base'             => 'pages',
 			'rest_controller_class' => 'WP_REST_Posts_Controller',
@@ -2329,7 +2349,6 @@ function post_type_supports( $post_type, $feature ) {
 
 	return ( isset( $_wp_post_type_features[ $post_type ][ $feature ] ) );
 }
-
 /**
  * Retrieves a list of post type names that support a specific feature.
  *

src/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php

@@ -123,11 +123,21 @@ public function register_routes() {
 	 * @return true|WP_Error True if the request has read access, error object otherwise.
 	 */
 	public function get_items_permissions_check( $request ) {
+		$is_note         = 'note' === $request['type'];
+		$is_edit_context = 'edit' === $request['context'];
 
 		if ( ! empty( $request['post'] ) ) {
 			foreach ( (array) $request['post'] as $post_id ) {
 				$post = get_post( $post_id );
 
+				if ( $post && $is_note && ! $this->check_post_type_supports_notes( $post->post_type ) ) {
+					return new WP_Error(
+						'rest_comment_not_supported_post_type',
+						__( 'Sorry, this post type does not support notes.' ),
+						array( 'status' => 403 )
+					);
+				}
+
 				if ( ! empty( $post_id ) && $post && ! $this->check_read_post_permission( $post, $request ) ) {
 					return new WP_Error(
 						'rest_cannot_read_post',
@@ -144,7 +154,18 @@ public function get_items_permissions_check( $request ) {
 			}
 		}
 
-		if ( ! empty( $request['context'] ) && 'edit' === $request['context'] && ! current_user_can( 'moderate_comments' ) ) {
+		// Re-map edit context capabilities when requesting `note` for a post.
+		if ( $is_edit_context && $is_note && ! empty( $request['post'] ) ) {
+			foreach ( (array) $request['post'] as $post_id ) {
+				if ( ! current_user_can( 'edit_post', $post_id ) ) {
+					return new WP_Error(
+						'rest_forbidden_context',
+						__( 'Sorry, you are not allowed to edit comments.' ),
+						array( 'status' => rest_authorization_required_code() )
+					);
+				}
+			}
+		} elseif ( $is_edit_context && ! current_user_can( 'moderate_comments' ) ) {
 			return new WP_Error(
 				'rest_forbidden_context',
 				__( 'Sorry, you are not allowed to edit comments.' ),
@@ -394,7 +415,9 @@ public function get_item_permissions_check( $request ) {
 			return $comment;
 		}
 
-		if ( ! empty( $request['context'] ) && 'edit' === $request['context'] && ! current_user_can( 'moderate_comments' ) ) {
+		// Re-map edit context capabilities when requesting `note` type.
+		$edit_cap = 'note' === $comment->comment_type ? array( 'edit_comment', $comment->comment_ID ) : array( 'moderate_comments' );
+		if ( ! empty( $request['context'] ) && 'edit' === $request['context'] && ! current_user_can( ...$edit_cap ) ) {
 			return new WP_Error(
 				'rest_forbidden_context',
 				__( 'Sorry, you are not allowed to edit comments.' ),
@@ -452,6 +475,16 @@ public function get_item( $request ) {
 	 * @return true|WP_Error True if the request has access to create items, error object otherwise.
 	 */
 	public function create_item_permissions_check( $request ) {
+		$is_note = ! empty( $request['type'] ) && 'note' === $request['type'];
+
+		if ( ! is_user_logged_in() && $is_note ) {
+			return new WP_Error(
+				'rest_comment_login_required',
+				__( 'Sorry, you must be logged in to comment.' ),
+				array( 'status' => 401 )
+			);
+		}
+
 		if ( ! is_user_logged_in() ) {
 			if ( get_option( 'comment_registration' ) ) {
 				return new WP_Error(
@@ -505,7 +538,8 @@ public function create_item_permissions_check( $request ) {
 			}
 		}
 
-		if ( isset( $request['status'] ) && ! current_user_can( 'moderate_comments' ) ) {
+		$edit_cap = $is_note ? array( 'edit_post', (int) $request['post'] ) : array( 'moderate_comments' );
+		if ( isset( $request['status'] ) && ! current_user_can( ...$edit_cap ) ) {
 			return new WP_Error(
 				'rest_comment_invalid_status',
 				/* translators: %s: Request parameter. */
@@ -532,7 +566,15 @@ public function create_item_permissions_check( $request ) {
 			);
 		}
 
-		if ( 'draft' === $post->post_status ) {
+		if ( $is_note && ! $this->check_post_type_supports_notes( $post->post_type ) ) {
+			return new WP_Error(
+				'rest_comment_not_supported_post_type',
+				__( 'Sorry, this post type does not support notes.' ),
+				array( 'status' => 403 )
+			);
+		}
+
+		if ( 'draft' === $post->post_status && ! $is_note ) {
 			return new WP_Error(
 				'rest_comment_draft_post',
 				__( 'Sorry, you are not allowed to create a comment on this post.' ),
@@ -556,7 +598,7 @@ public function create_item_permissions_check( $request ) {
 			);
 		}
 
-		if ( ! comments_open( $post->ID ) ) {
+		if ( ! comments_open( $post->ID ) && ! $is_note ) {
 			return new WP_Error(
 				'rest_comment_closed',
 				__( 'Sorry, comments are closed for this item.' ),
@@ -584,8 +626,8 @@ public function create_item( $request ) {
 			);
 		}
 
-		// Do not allow comments to be created with a non-default type.
-		if ( ! empty( $request['type'] ) && 'comment' !== $request['type'] ) {
+		// Do not allow comments to be created with a non-core type.
+		if ( ! empty( $request['type'] ) && ! in_array( $request['type'], array( 'comment', 'note' ), true ) ) {
 			return new WP_Error(
 				'rest_invalid_comment_type',
 				__( 'Cannot create a comment with that type.' ),
@@ -598,12 +640,17 @@ public function create_item( $request ) {
 			return $prepared_comment;
 		}
 
-		$prepared_comment['comment_type'] = 'comment';
+		$prepared_comment['comment_type'] = $request['type'];
 
 		if ( ! isset( $prepared_comment['comment_content'] ) ) {
 			$prepared_comment['comment_content'] = '';
 		}
 
+		// Include note metadata into check_is_comment_content_allowed.
+		if ( isset( $request['meta']['_wp_note_status'] ) ) {
+			$prepared_comment['meta']['_wp_note_status'] = $request['meta']['_wp_note_status'];
+		}
+
 		if ( ! $this->check_is_comment_content_allowed( $prepared_comment ) ) {
 			return new WP_Error(
 				'rest_comment_content_invalid',
@@ -1519,6 +1566,7 @@ public function get_item_schema() {
 					'type'        => 'string',
 					'context'     => array( 'view', 'edit', 'embed' ),
 					'readonly'    => true,
+					'default'     => 'comment',
 				),
 			),
 		);
@@ -1925,10 +1973,42 @@ protected function check_is_comment_content_allowed( $prepared_comment ) {
 			return true;
 		}
 
+		// Allow empty notes only when resolution metadata is valid.
+		if (
+			isset( $check['comment_type'] ) &&
+			'note' === $check['comment_type'] &&
+			isset( $check['meta']['_wp_note_status'] ) &&
+			in_array( $check['meta']['_wp_note_status'], array( 'resolved', 'reopen' ), true )
+		) {
+			return true;
+		}
+
 		/*
 		 * Do not allow a comment to be created with missing or empty
 		 * comment_content. See wp_handle_comment_submission().
 		 */
 		return '' !== $check['comment_content'];
 	}
+
+	/**
+	 * Check if post type supports notes.
+	 *
+	 * @param string $post_type Post type name.
+	 * @return bool True if post type supports notes, false otherwise.
+	 */
+	private function check_post_type_supports_notes( $post_type ) {
+		$supports = get_all_post_type_supports( $post_type );
+		if ( ! isset( $supports['editor'] ) ) {
+			return false;
+		}
+		if ( ! is_array( $supports['editor'] ) ) {
+			return false;
+		}
+		foreach ( $supports['editor'] as $item ) {
+			if ( ! empty( $item['notes'] ) ) {
+				return true;
+			}
+		}
+		return false;
+	}
 }