fix: #3606969 Content translation column group settings only show up once...

                '#default_value' => $definition->isTranslatable(),

              ];

              // Display the column translatability configuration widget.

              $column_element = $this->fieldSyncWidget->widget($definition, "settings[{$entity_type_id}][{$bundle}][columns][{$field_name}]");

              // Base field definitions do not carry third-party settings.

              // Use the bundle-level config wrapper so sync options are

              // available even before a BaseFieldOverride is explicitly saved.

              $field_for_sync_widget = $definition->getFieldStorageDefinition()->isBaseField()

                ? $definition->getConfig($bundle)

                : $definition;

              $column_element = $this->fieldSyncWidget->widget($field_for_sync_widget, "settings[{$entity_type_id}][{$bundle}][columns][{$field_name}]");

              if ($column_element) {

                $form['settings'][$entity_type_id][$bundle]['columns'][$field_name] = $column_element;

              }

<?php

declare(strict_types=1);

namespace Drupal\Tests\content_translation\Functional;

use Drupal\Tests\BrowserTestBase;

use Drupal\Tests\media\Traits\MediaTypeCreationTrait;

use PHPUnit\Framework\Attributes\Group;

use PHPUnit\Framework\Attributes\RunTestsInSeparateProcesses;

/**

 * Tests base-field translation sync options on content language settings form.

 */

#[RunTestsInSeparateProcesses]

#[Group('content_translation')]

final class ContentLanguageBaseFieldSyncWidgetTest extends BrowserTestBase {

  use MediaTypeCreationTrait;

  /**

   * {@inheritdoc}

   */

  protected $defaultTheme = 'stark';

  /**

   * {@inheritdoc}

   */

  protected static $modules = [

    'content_translation',

    'language',

    'media',

    'media_test_source',

  ];

  /**

   * Tests translation sync options appear for translatable base fields.

   */

  public function testBaseFieldSyncOptionsVisibleOnFirstLoad(): void {

    $account = $this->drupalCreateUser([

      'administer languages',

      'administer content translation',

      'administer media',

      'administer media types',

    ]);

    $this->drupalLogin($account);

    $media_type = $this->createMediaType('test');

    $this->drupalGet('admin/config/regional/content-language');

    $assert_session = $this->assertSession();

    $assert_session->statusCodeEquals(200);

    // Regression test: before any save/create of a base field override, the

    // column-group sync options for a translatable base field must be present.

    $assert_session->elementExists('css', 'input[name="settings[media][' . $media_type->id() . '][fields][thumbnail]"]');

    $assert_session->elementExists('css', 'input[name="settings[media][' . $media_type->id() . '][columns][thumbnail][file]"]');

    $assert_session->elementExists('css', 'input[name="settings[media][' . $media_type->id() . '][columns][thumbnail][alt]"]');

    $assert_session->elementExists('css', 'input[name="settings[media][' . $media_type->id() . '][columns][thumbnail][title]"]');

  }

}