Initial Drupal 11 with DDEV setup

web/core/modules/layout_discovery/src/Hook/LayoutDiscoveryHooks.php

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+<?php
+
+namespace Drupal\layout_discovery\Hook;
+
+use Drupal\Core\Hook\Attribute\Hook;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+
+/**
+ * Hook implementations for layout_discovery.
+ */
+class LayoutDiscoveryHooks {
+
+  use StringTranslationTrait;
+
+  /**
+   * Implements hook_help().
+   */
+  #[Hook('help')]
+  public function help($route_name): ?string {
+    switch ($route_name) {
+      case 'help.page.layout_discovery':
+        $output = '<h2>' . $this->t('About') . '</h2>';
+        $output .= '<p>' . $this->t('Layout Discovery allows modules or themes to register layouts, and for other modules to list the available layouts and render them.') . '</p>';
+        $output .= '<p>' . $this->t('For more information, see the <a href=":layout-discovery-documentation">online documentation for the Layout Discovery module</a>.', [
+          ':layout-discovery-documentation' => 'https://www.drupal.org/docs/8/api/layout-api',
+        ]) . '</p>';
+        return $output;
+    }
+    return NULL;
+  }
+
+  /**
+   * Implements hook_theme().
+   */
+  #[Hook('theme')]
+  public function theme() : array {
+    return \Drupal::service('plugin.manager.core.layout')->getThemeImplementations();
+  }
+
+}

web/core/modules/layout_discovery/src/Install/Requirements/LayoutDiscoveryRequirements.php

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+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\layout_discovery\Install\Requirements;
+
+use Drupal\Core\Extension\InstallRequirementsInterface;
+use Drupal\Core\Extension\Requirement\RequirementSeverity;
+
+/**
+ * Install time requirements for the layout_discovery module.
+ */
+class LayoutDiscoveryRequirements implements InstallRequirementsInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getRequirements(): array {
+    $requirements = [];
+    if (\Drupal::moduleHandler()->moduleExists('layout_plugin')) {
+      $requirements['layout_discovery'] = [
+        'description' => t('Layout Discovery cannot be installed because the Layout Plugin module is installed and incompatible.'),
+        'severity' => RequirementSeverity::Error,
+      ];
+    }
+    return $requirements;
+  }
+
+}