View Config: Add the form of the root/site entity

src/wp-includes/default-filters.php

@@ -834,5 +834,6 @@
 		5
 	);
 }
+add_filter( 'get_entity_view_config_root_site', '_wp_get_entity_view_config_root_site', 5 );
 
 unset( $filter, $action, $post_type );

src/wp-includes/view-config.php

@@ -769,3 +769,36 @@ function _wp_get_entity_view_config_posttype_wp_template( $data ) {
 
 	return $data;
 }
+
+/**
+ * Provides the view configuration for the `root`/`site` entity.
+ *
+ * The site settings are a singleton record edited through a form (the site
+ * editor's Identity screen) rather than listed in a view, so only the `form`
+ * is defined here. The generic `default_view`, `default_layouts`, and
+ * `view_list` built by wp_get_entity_view_config() are left untouched.
+ *
+ * @since 7.2.0
+ *
+ * @param WP_View_Config_Data $data The view configuration container for the entity.
+ * @return WP_View_Config_Data The updated view configuration container.
+ */
+function _wp_get_entity_view_config_root_site( $data ) {
+	return $data->set(
+		array(
+			'form' => array(
+				'layout' => array(
+					'type'          => 'regular',
+					'labelPosition' => 'top',
+				),
+				'fields' => array(
+					'title',
+					'description',
+					'site_logo',
+					'site_icon',
+				),
+			),
+		),
+		1
+	);
+}

tests/phpunit/tests/rest-api/rest-view-config-controller.php

@@ -302,6 +302,35 @@ public function test_get_items_matches_underlying_config() {
 		$this->assertSame( $config['form'], $data['form'] );
 	}
 
+	/**
+	 * The `root`/`site` entity provides the form of the site identity screen.
+	 *
+	 * @ticket 65981
+	 *
+	 * @covers ::get_items
+	 */
+	public function test_get_items_root_site_form() {
+		// Admin: reading root config requires `manage_options`.
+		wp_set_current_user( self::$admin_id );
+
+		$response = $this->dispatch_request( 'root', 'site' );
+		$this->assertSame( 200, $response->get_status() );
+
+		$data = json_decode( wp_json_encode( $response->get_data() ), true );
+
+		$this->assertSame(
+			array(
+				'type'          => 'regular',
+				'labelPosition' => 'top',
+			),
+			$data['form']['layout']
+		);
+		$this->assertSame(
+			array( 'title', 'description', 'site_logo', 'site_icon' ),
+			$data['form']['fields']
+		);
+	}
+
 	/**
 	 * Empty object-typed config values serialize as JSON objects ({}), not arrays ([]).
 	 *