Editor: Add the entity actions API

src/wp-includes/default-filters.php

@@ -853,4 +853,7 @@
 }
 add_filter( 'get_entity_view_config_root_site', '_wp_get_entity_view_config_root_site', 5 );
 
+// Entity Actions API.
+add_action( 'admin_footer', '_wp_add_entity_action_modules_to_editor_script', 10, 0 );
+
 unset( $filter, $action, $post_type );

src/wp-includes/entity-actions.php

@@ -0,0 +1,188 @@
+<?php
+/**
+ * Entity actions API.
+ *
+ * An action definition is the serializable subset of the DataViews Action
+ * API: every property that is plain data (`id`, `label`, `isPrimary`,
+ * `supportsBulk`, `context`, `modalHeader`, …). Properties that are
+ * JavaScript callbacks, components, or elements (`callback`, `RenderModal`,
+ * `isEligible`, `icon`, a `label` that depends on the items, …) cannot be
+ * declared here. They are provided by a script module registered for the
+ * entity along with its actions: its default export maps action ids to the
+ * properties of each action that are JavaScript. An entity can have several
+ * modules. Each module applies to the actions it was registered with, see
+ * {@see wp_get_registered_entity_action_modules()}.
+ *
+ * Actions are registered on the `wp_entity_actions_api_init` action, and only there,
+ * with {@see wp_register_entity_actions()} and {@see wp_unregister_entity_actions()}. The
+ * other functions read the registry.
+ *
+ * @package WordPress
+ * @subpackage Entity Actions
+ * @since 7.2.0
+ */
+
+/**
+ * Registers actions for an entity, see
+ * {@see WP_Entity_Actions_Registry::register()}.
+ *
+ * It only runs on the `wp_entity_actions_api_init` action.
+ *
+ * @since 7.2.0
+ *
+ * @param string      $origin        Who registers the actions: `core`, or
+ *                                   the slug of the plugin or theme.
+ * @param string      $kind          The entity kind (e.g. `postType`).
+ * @param string      $name          The entity name (e.g. `page`).
+ * @param array[]     $actions       The list of action definitions, each with an `id`.
+ * @param string|null $script_module The id of the script module providing
+ *                                   the JavaScript parts of the actions, if any.
+ * @return string[] The ids of the actions registered, in the order of the
+ *                  call. Empty when none is.
+ */
+function wp_register_entity_actions( $origin, $kind, $name, $actions, $script_module = null ) {
+	return WP_Entity_Actions_Registry::get_instance()->register( $origin, $kind, $name, $actions, $script_module );
+}
+
+/**
+ * Unregisters actions of an entity, see
+ * {@see WP_Entity_Actions_Registry::unregister()}.
+ *
+ * It only runs on the `wp_entity_actions_api_init` action.
+ *
+ * @since 7.2.0
+ *
+ * @param string        $kind The entity kind (e.g. `postType`).
+ * @param string        $name The entity name (e.g. `page`).
+ * @param string[]|null $ids  The ids of the actions to unregister. Default
+ *                            null, every action of the entity.
+ * @return array[] The list of the definitions unregistered, in
+ *                 registration order. Empty when none is.
+ */
+function wp_unregister_entity_actions( $kind, $name, $ids = null ) {
+	return WP_Entity_Actions_Registry::get_instance()->unregister( $kind, $name, $ids );
+}
+
+/**
+ * Returns the actions registered for the given entity.
+ *
+ * @since 7.2.0
+ *
+ * @param string $kind The entity kind (e.g. `postType`).
+ * @param string $name The entity name (e.g. `page`).
+ * @return array[] The list of registered action definitions, in
+ *                 registration order. Empty until the `init` action has
+ *                 completed: a read before then is refused.
+ */
+function wp_get_registered_entity_actions( $kind, $name ) {
+	return WP_Entity_Actions_Registry::get_instance()->get_registered( $kind, $name );
+}
+
+/**
+ * Returns the ids of the script modules registered for the given entity.
+ *
+ * @since 7.2.0
+ *
+ * @param string $kind The entity kind (e.g. `postType`).
+ * @param string $name The entity name (e.g. `page`).
+ * @return array<string, string[]> The ids of the actions each module
+ *                                 applies to, keyed by module id, in
+ *                                 registration order. Empty until the
+ *                                 `init` action has completed: a read
+ *                                 before then is refused.
+ */
+function wp_get_registered_entity_action_modules( $kind, $name ) {
+	return WP_Entity_Actions_Registry::get_instance()->get_registered_action_modules( $kind, $name );
+}
+
+/**
+ * Returns the ids of all script modules registered for any entity.
+ *
+ * @since 7.2.0
+ *
+ * @return array<string, array<string, string[]>> The lists of module ids,
+ *                                                keyed by kind, then by
+ *                                                name. Empty until the
+ *                                                `init` action has
+ *                                                completed: a read before
+ *                                                then is refused.
+ */
+function wp_get_all_registered_entity_action_modules() {
+	return WP_Entity_Actions_Registry::get_instance()->get_all_registered_action_modules();
+}
+
+/**
+ * Declares the script modules of the entity actions as dependencies of the
+ * editor script.
+ *
+ * The editor imports the script modules of an entity on demand, with a dynamic
+ * `import()` the browser resolves through the import map of the page. Listing
+ * the modules as dynamic `module_dependencies` of the `wp-editor` script adds
+ * them to the import map of every page that loads the editor script: the post
+ * editor, the site editor, and the pages booted by `@wordpress/boot`, whose
+ * prerequisites depend on it. A dynamic dependency is only listed in the
+ * import map; the module is fetched when it is imported.
+ *
+ * Reading the registry fires `wp_entity_actions_api_init`, so the actions and their
+ * script modules are registered on demand. It only reads the registry on the
+ * pages that load the editor script, not on every admin request (heartbeat,
+ * Ajax, other screens). It runs on `admin_footer`, the last action before the
+ * import map is printed that fires both in the admin template and in the pages
+ * rendered outside it, which print the import map themselves. By then `init`
+ * has completed, so the post types and supports the actions derive from are
+ * final.
+ * The registry only accepts registrations while the action fires, so the
+ * modules declared here are the modules of every action the page can show.
+ *
+ * The `admin_footer` action passes it no argument, so the global registry is
+ * used. In other scenarios (tests), the scripts are given directly.
+ *
+ * @since 7.2.0
+ *
+ * @param WP_Scripts|null $scripts The scripts registry. Defaults to the global one.
+ */
+function _wp_add_entity_action_modules_to_editor_script( $scripts = null ) {
+	if ( ! $scripts instanceof WP_Scripts ) {
+		$scripts = wp_scripts();
+	}
+
+	// The actions are loaded by `usePostActions()` of the editor script, so
+	// every screen showing them loads it.
+	if ( ! $scripts->query( 'wp-editor', 'enqueued' ) && ! $scripts->query( 'wp-editor', 'done' ) ) {
+		return;
+	}
+
+	$kinds = wp_get_all_registered_entity_action_modules();
+	if ( empty( $kinds ) ) {
+		return;
+	}
+
+	$dependencies = $scripts->get_data( 'wp-editor', 'module_dependencies' );
+	$dependencies = is_array( $dependencies ) ? $dependencies : array();
+
+	$declared = array();
+	foreach ( $dependencies as $dependency ) {
+		$declared[] = is_array( $dependency ) ? $dependency['id'] : $dependency;
+	}
+
+	$added = false;
+	foreach ( $kinds as $entities ) {
+		foreach ( $entities as $modules ) {
+			foreach ( $modules as $module ) {
+				if ( ! in_array( $module, $declared, true ) ) {
+					$dependencies[] = array(
+						'id'     => $module,
+						'import' => 'dynamic',
+					);
+					$declared[]     = $module;
+					$added          = true;
+				}
+			}
+		}
+	}
+
+	if ( $added ) {
+		// `add_data()` replaces the value, hence the merge above.
+		$scripts->add_data( 'wp-editor', 'module_dependencies', $dependencies );
+	}
+}

src/wp-includes/rest-api.php

@@ -436,6 +436,10 @@ function create_initial_rest_routes() {
 	// View Config.
 	$view_config_controller = new WP_REST_View_Config_Controller();
 	$view_config_controller->register_routes();
+
+	// Entity Actions.
+	$entity_actions_controller = new WP_REST_Entity_Actions_Controller();
+	$entity_actions_controller->register_routes();
 }
 
 /**