Adiciona sub-módulo site_tools_group_helpers

Fornece um plugin EntityReferenceSelection que restringe campos de
referência a grupos aos grupos dos quais o usuário atual é membro.
Inclui troca automática para o widget options_select ao configurar o
handler, e remoção do #required em target_bundles para campos que
referenciam group, permitindo deixar o tipo de grupo em branco.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

modules/site_tools_group_helpers/src/Plugin/EntityReferenceSelection/MemberGroupSelection.php

@@ -0,0 +1,64 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\site_tools_group_helpers\Plugin\EntityReferenceSelection;
+
+use Drupal\Core\Entity\Attribute\EntityReferenceSelection;
+use Drupal\Core\Entity\Plugin\EntityReferenceSelection\DefaultSelection;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
+use Drupal\group\Entity\GroupMembership;
+
+/**
+ * Restricts group selection to groups where the current user is a member.
+ *
+ * Use this handler on any entity_reference field that targets the 'group'
+ * entity type when only the groups the current user belongs to should appear
+ * as options. Users with no memberships will see an empty list.
+ */
+#[EntityReferenceSelection(
+  id: 'site_tools_group_helpers',
+  label: new TranslatableMarkup('Member groups (current user)'),
+  entity_types: ['group'],
+  group: 'site_tools_group_helpers',
+  weight: 0,
+)]
+class MemberGroupSelection extends DefaultSelection {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
+    $form = parent::buildConfigurationForm($form, $form_state);
+
+    // Allow leaving group types empty (= any type), matching the behaviour
+    // of the default selection handler.
+    if (isset($form['target_bundles'])) {
+      $form['target_bundles']['#required'] = FALSE;
+    }
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function buildEntityQuery($match = NULL, $match_operator = 'CONTAINS') {
+    $query = parent::buildEntityQuery($match, $match_operator);
+
+    $memberships = GroupMembership::loadByUser($this->currentUser);
+
+    if (empty($memberships)) {
+      // User has no memberships — return an empty result set.
+      $query->condition('id', 0, '=');
+      return $query;
+    }
+
+    $gids = array_map(fn($m) => $m->getGroupId(), $memberships);
+    $query->condition('id', $gids, 'IN');
+
+    return $query;
+  }
+
+}