added popup

README.md

@@ -20,7 +20,7 @@ It then checks the underlying media Action's access for each media entity and ex
 
 3. Go to:
 
-   `/admin/config/islandora/node-media-actions`
+   `/admin/config/content/node-media-actions`
 
 4. Click **Add node media action**.
 5. Enter the label you want exposed at node level and choose an existing configured media Action.

src/Form/BridgeForm.php

@@ -7,6 +7,8 @@ use Drupal\Core\Form\FormStateInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Action\ActionManager;
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Ajax\OpenModalDialogCommand;
 
 /**
  * Add/edit form for node media Action wrappers.
@@ -59,6 +61,20 @@ class BridgeForm extends FormBase {
     }
     natcasesort($options);
 
+    $form['#attached']['library'][] = 'core/drupal.dialog.ajax';
+
+    $form['usage_help'] = [
+      '#type' => 'button',
+      '#value' => $this->t('How to use this form'),
+      '#ajax' => [
+        'callback' => '::usageHelpModal',
+      ],
+      '#attributes' => [
+        'class' => ['button', 'button--small'],
+      ],
+      '#limit_validation_errors' => [],
+    ];
+
     $form['label'] = [
       '#type' => 'textfield',
       '#title' => $this->t('Node Action label'),
@@ -103,6 +119,43 @@ class BridgeForm extends FormBase {
     return $form;
   }
 
+  /**
+   * Opens the usage instructions in a modal dialog.
+   */
+  public function usageHelpModal(array &$form, FormStateInterface $form_state): AjaxResponse {
+    $content = [
+      '#type' => 'container',
+      'intro' => [
+        '#markup' => '<p>' . $this->t('This form creates a node-level Action that runs an existing configured media Action against every media item whose <code>field_media_of</code> references the selected node.') . '</p>',
+      ],
+      'steps' => [
+        '#theme' => 'item_list',
+        '#list_type' => 'ol',
+        '#items' => [
+          $this->t('Enter the label you want users to see when selecting the node Action.'),
+          $this->t('Accept the generated machine name, or change it before the Action is first saved.'),
+          $this->t('Choose the configured media Action that should be executed for the node’s associated media.'),
+          $this->t('Click Save. The module creates a configured node Action automatically.'),
+          $this->t('Use that node Action from Views Bulk Operations, the Collection Manager, or any other interface that exposes configured node Actions.'),
+        ],
+      ],
+      'notes' => [
+        '#markup' => '<p><strong>' . $this->t('What happens when it runs:') . '</strong> ' . $this->t('The wrapper finds all media referencing the node through field_media_of, checks access for the selected media Action, and executes that Action against the eligible media items.') . '</p>',
+      ],
+      'tip' => [
+        '#markup' => '<p><strong>' . $this->t('Tip:') . '</strong> ' . $this->t('If the media Action you need is not listed, configure/create that media Action first, then return to this form.') . '</p>',
+      ],
+    ];
+
+    $response = new AjaxResponse();
+    $response->addCommand(new OpenModalDialogCommand(
+      $this->t('How to use this form'),
+      $content,
+      ['width' => 700],
+    ));
+    return $response;
+  }
+
   /**
    * Machine-name existence callback.
    */