simple_page_manager-1.0.0-alpha1/simple_page_manager.module

<?php

use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Url;
use Drupal\simple_page_manager\Entity\Page;

/**
 * Implements hook_entity_operation().
 */
function simple_page_manager_entity_operation(EntityInterface $entity) {
  $operations = [];

  if ($entity instanceof Page) {
    $operations['layout'] = [
      'title' => t('Layout'),
      'weight' => 5,
      'url' => Url::fromRoute('layout_builder.page.view', ['page' => $entity->id()]),
    ];
  }

  return $operations;
}

/**
 * Page URI callback.
 */
function page_uri(Page $page) {
  $id = $page->id();
  return new Url(
    "entity.page.${id}.canonical",
    [
      'page' => $id,
    ],
  );
}