diff --git a/src/Attribute/ITranslatedWithFallbackControl.php b/src/Attribute/ITranslatedWithFallbackControl.php
new file mode 100644
index 000000000..8049a72fe
--- /dev/null
+++ b/src/Attribute/ITranslatedWithFallbackControl.php
@@ -0,0 +1,57 @@
+<?php
+
+/**
+ * This file is part of MetaModels/core.
+ *
+ * (c) 2012-2026 The MetaModels team.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * This project is provided in good faith and hope to be usable by anyone.
+ *
+ * @package    MetaModels/core
+ * @author     Ingolf Steinhardt <info@e-spin.de>
+ * @copyright  2012-2026 The MetaModels team.
+ * @license    https://github.com/MetaModels/core/blob/master/LICENSE LGPL-3.0-or-later
+ * @filesource
+ */
+
+namespace MetaModels\Attribute;
+
+/**
+ * Extended interface for translated attributes that support fetching raw per-language data without automatic fallback
+ * to the main language.
+ *
+ * This separate interface allows opt-in without breaking existing ITranslated implementors.
+ * Consumers check instanceof before calling getTranslatedDataForWithoutFallback().
+ */
+interface ITranslatedWithFallbackControl extends ITranslated
+{
+    /**
+     * Get values for the given items in a certain language without falling back to the main language.
+     *
+     * Unlike getTranslatedDataFor(), this method returns only data actually stored for $strLangCode.
+     * No second pass against the main language is performed.
+     *
+     * @param list<string> $arrIds      The ids for which values shall be retrieved.
+     * @param string       $strLangCode The language code for which the data shall be retrieved.
+     *
+     * @return array<string, array<string, mixed>> the values.
+     */
+    public function getTranslatedDataForWithoutFallback(array $arrIds, string $strLangCode): array;
+
+    /**
+     * Save translated data for a given language, potentially with attribute-specific transformation.
+     *
+     * Implementations may transform the data before persisting it — e.g. a unique-alias attribute
+     * re-generates the slug to satisfy its uniqueness constraint. The default behaviour is to call
+     * setTranslatedDataFor() verbatim.
+     *
+     * @param array<string, array<string, mixed>> $arrValues   The values keyed by item id.
+     * @param string                              $strLangCode The language code being processed.
+     *
+     * @return void
+     */
+    public function applyTranslatedDataFor(array $arrValues, string $strLangCode): void;
+}
diff --git a/src/Attribute/TranslatedReference.php b/src/Attribute/TranslatedReference.php
index f7cea603e..b8cf6e05c 100644
--- a/src/Attribute/TranslatedReference.php
+++ b/src/Attribute/TranslatedReference.php
@@ -3,7 +3,7 @@
 /**
  * This file is part of MetaModels/core.
  *
- * (c) 2012-2024 The MetaModels team.
+ * (c) 2012-2026 The MetaModels team.
  *
  * For the full copyright and license information, please view the LICENSE
  * file that was distributed with this source code.
@@ -19,7 +19,7 @@
  * @author     Sven Baumann <baumann.sv@gmail.com>
  * @author     David Molineus <david.molineus@netzmacht.de>
  * @author     Andreas Fischer <anfischer@kaffee-partner.de>
- * @copyright  2012-2024 The MetaModels team.
+ * @copyright  2012-2026 The MetaModels team.
  * @license    https://github.com/MetaModels/core/blob/master/LICENSE LGPL-3.0-or-later
  * @filesource
  */
@@ -38,7 +38,7 @@
  *
  * @SuppressWarnings(PHPMD.ExcessiveClassComplexity)
  */
-abstract class TranslatedReference extends BaseComplex implements ITranslated
+abstract class TranslatedReference extends BaseComplex implements ITranslatedWithFallbackControl
 {
     /**
      * Database connection.
@@ -455,6 +455,24 @@ protected function fetchExistingIdsFor($idList, $langCode)
         return $queryBuilder->executeQuery()->fetchFirstColumn();
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    #[\Override]
+    public function getTranslatedDataForWithoutFallback(array $arrIds, string $strLangCode): array
+    {
+        return $this->getTranslatedDataFor($arrIds, $strLangCode);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    #[\Override]
+    public function applyTranslatedDataFor(array $arrValues, string $strLangCode): void
+    {
+        $this->setTranslatedDataFor($arrValues, $strLangCode);
+    }
+
     /**
      * {@inheritDoc}
      */
diff --git a/src/CoreBundle/Resources/config/listeners.yml b/src/CoreBundle/Resources/config/listeners.yml
index 853888651..2db7e2d24 100644
--- a/src/CoreBundle/Resources/config/listeners.yml
+++ b/src/CoreBundle/Resources/config/listeners.yml
@@ -48,6 +48,24 @@ services:
                 event: dc-general.model.pre-duplicate
                 method: handle
 
+    metamodels.copy_translated_data_listener:
+        class: MetaModels\DcGeneral\Events\MetaModel\CopyTranslatedData
+        arguments:
+            - "@metamodels.factory"
+        tags:
+            -   name: kernel.event_listener
+                event: dc-general.model.post-duplicate
+                method: handle
+
+    metamodels.reset_language_after_duplicate_listener:
+        class: MetaModels\DcGeneral\Events\MetaModel\ResetLanguageAfterDuplicate
+        arguments:
+            - "@metamodels.factory"
+        tags:
+            -   name: kernel.event_listener
+                event: dc-general.model.post-duplicate
+                method: handle
+
     metamodels.sub_system_boot:
         class: MetaModels\CoreBundle\EventListener\SubSystemBootListener
         arguments:
diff --git a/src/DcGeneral/Events/MetaModel/CopyTranslatedData.php b/src/DcGeneral/Events/MetaModel/CopyTranslatedData.php
new file mode 100644
index 000000000..8b380e654
--- /dev/null
+++ b/src/DcGeneral/Events/MetaModel/CopyTranslatedData.php
@@ -0,0 +1,108 @@
+<?php
+
+/**
+ * This file is part of MetaModels/core.
+ *
+ * (c) 2012-2026 The MetaModels team.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * This project is provided in good faith and hope to be usable by anyone.
+ *
+ * @package    MetaModels/core
+ * @author     Ingolf Steinhardt <info@e-spin.de>
+ * @copyright  2012-2026 The MetaModels team.
+ * @license    https://github.com/MetaModels/core/blob/master/LICENSE LGPL-3.0-or-later
+ * @filesource
+ */
+
+namespace MetaModels\DcGeneral\Events\MetaModel;
+
+use ContaoCommunityAlliance\DcGeneral\Event\PostDuplicateModelEvent;
+use MetaModels\Attribute\ITranslatedWithFallbackControl;
+use MetaModels\IFactory;
+use MetaModels\ITranslatedMetaModel;
+
+/**
+ * Copies translated attribute data for all languages when an item is duplicated.
+ *
+ * The normal DC_General duplicate path only saves data for the currently active language. This listener runs after
+ * the copy has been persisted and iterates every language, copying each translated attribute's raw (non-fallback) data
+ * from the source item to the new item.
+ */
+final class CopyTranslatedData
+{
+    /**
+     * The MetaModels factory.
+     *
+     * @var IFactory
+     */
+    private IFactory $factory;
+
+    /**
+     * Create a new instance.
+     *
+     * @param IFactory $factory The factory.
+     */
+    public function __construct(IFactory $factory)
+    {
+        $this->factory = $factory;
+    }
+
+    /**
+     * Copy translated data for all languages after a model has been duplicated.
+     *
+     * @param PostDuplicateModelEvent $event The event.
+     *
+     * @return void
+     */
+    public function handle(PostDuplicateModelEvent $event): void
+    {
+        $sourceId = (string) $event->getSourceModel()->getId();
+        $newId    = (string) $event->getModel()->getId();
+
+        if ('' === $sourceId || '' === $newId || $sourceId === $newId) {
+            return;
+        }
+
+        $metaModel = $this->factory->getMetaModel($event->getModel()->getProviderName());
+        if (!$metaModel instanceof ITranslatedMetaModel) {
+            return;
+        }
+
+        foreach ($metaModel->getLanguages() as $language) {
+            $this->copyLanguage($metaModel, $language, $sourceId, $newId);
+        }
+    }
+
+    /**
+     * Copy all translated attributes for a single language.
+     *
+     * @param ITranslatedMetaModel $metaModel The MetaModel.
+     * @param string               $language  The language code.
+     * @param string               $sourceId  The source item ID.
+     * @param string               $newId     The new item ID.
+     *
+     * @return void
+     */
+    private function copyLanguage(
+        ITranslatedMetaModel $metaModel,
+        string $language,
+        string $sourceId,
+        string $newId
+    ): void {
+        foreach ($metaModel->getAttributes() as $attribute) {
+            if (!$attribute instanceof ITranslatedWithFallbackControl) {
+                continue;
+            }
+
+            $data = $attribute->getTranslatedDataForWithoutFallback([$sourceId], $language);
+            if ([] === $data || !isset($data[$sourceId])) {
+                continue;
+            }
+
+            $attribute->applyTranslatedDataFor([$newId => $data[$sourceId]], $language);
+        }
+    }
+}
diff --git a/src/DcGeneral/Events/MetaModel/ResetLanguageAfterDuplicate.php b/src/DcGeneral/Events/MetaModel/ResetLanguageAfterDuplicate.php
new file mode 100644
index 000000000..6bd088056
--- /dev/null
+++ b/src/DcGeneral/Events/MetaModel/ResetLanguageAfterDuplicate.php
@@ -0,0 +1,79 @@
+<?php
+
+/**
+ * This file is part of MetaModels/core.
+ *
+ * (c) 2012-2026 The MetaModels team.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * This project is provided in good faith and hope to be usable by anyone.
+ *
+ * @package    MetaModels/core
+ * @author     Ingolf Steinhardt <info@e-spin.de>
+ * @copyright  2012-2026 The MetaModels team.
+ * @license    https://github.com/MetaModels/core/blob/master/LICENSE LGPL-3.0-or-later
+ * @filesource
+ */
+
+namespace MetaModels\DcGeneral\Events\MetaModel;
+
+use ContaoCommunityAlliance\DcGeneral\Event\PostDuplicateModelEvent;
+use ContaoCommunityAlliance\DcGeneral\SessionStorageInterface;
+use MetaModels\IFactory;
+use MetaModels\ITranslatedMetaModel;
+
+/**
+ * Resets the active language to the fallback language after a model is duplicated.
+ *
+ * When a new record is created, LanguageFilter automatically resets to the fallback language. Copying a record
+ * redirects to act=edit with the new ID, so LanguageFilter does not apply the reset. This listener writes the
+ * fallback language into the dc-general session so that the subsequent edit opens in the fallback language,
+ * consistent with the behaviour for new records.
+ */
+final class ResetLanguageAfterDuplicate
+{
+    /**
+     * The MetaModels factory.
+     *
+     * @var IFactory
+     */
+    private IFactory $factory;
+
+    /**
+     * Create a new instance.
+     *
+     * @param IFactory $factory The factory.
+     */
+    public function __construct(IFactory $factory)
+    {
+        $this->factory = $factory;
+    }
+
+    /**
+     * Reset the session language to the fallback after a model has been duplicated.
+     *
+     * @param PostDuplicateModelEvent $event The event.
+     *
+     * @return void
+     */
+    public function handle(PostDuplicateModelEvent $event): void
+    {
+        $model        = $event->getModel();
+        $providerName = $model->getProviderName();
+
+        $metaModel = $this->factory->getMetaModel($providerName);
+        if (!$metaModel instanceof ITranslatedMetaModel) {
+            return;
+        }
+
+        $environment    = $event->getEnvironment();
+        $sessionStorage = $environment->getSessionStorage();
+        assert($sessionStorage instanceof SessionStorageInterface);
+
+        $session                               = (array) $sessionStorage->get('dc_general');
+        $session['ml_support'][$providerName]  = $metaModel->getMainLanguage();
+        $sessionStorage->set('dc_general', $session);
+    }
+}
diff --git a/tests/DcGeneral/Events/MetaModel/CopyTranslatedDataTest.php b/tests/DcGeneral/Events/MetaModel/CopyTranslatedDataTest.php
new file mode 100644
index 000000000..1c41188c4
--- /dev/null
+++ b/tests/DcGeneral/Events/MetaModel/CopyTranslatedDataTest.php
@@ -0,0 +1,267 @@
+<?php
+
+/**
+ * This file is part of MetaModels/core.
+ *
+ * (c) 2012-2026 The MetaModels team.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * This project is provided in good faith and hope to be usable by anyone.
+ *
+ * @package    MetaModels/core
+ * @author     Ingolf Steinhardt <info@e-spin.de>
+ * @copyright  2012-2026 The MetaModels team.
+ * @license    https://github.com/MetaModels/core/blob/master/LICENSE LGPL-3.0-or-later
+ * @filesource
+ */
+
+namespace MetaModels\Test\DcGeneral\Events\MetaModel;
+
+use ContaoCommunityAlliance\DcGeneral\Data\ModelInterface;
+use ContaoCommunityAlliance\DcGeneral\EnvironmentInterface;
+use ContaoCommunityAlliance\DcGeneral\Event\PostDuplicateModelEvent;
+use MetaModels\Attribute\ITranslated;
+use MetaModels\Attribute\ITranslatedWithFallbackControl;
+use MetaModels\DcGeneral\Events\MetaModel\CopyTranslatedData;
+use MetaModels\IFactory;
+use MetaModels\IMetaModel;
+use MetaModels\ITranslatedMetaModel;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \MetaModels\DcGeneral\Events\MetaModel\CopyTranslatedData
+ */
+class CopyTranslatedDataTest extends TestCase
+{
+    /**
+     * Build a PostDuplicateModelEvent with the given IDs and provider name.
+     *
+     * @param string $sourceId     The source item ID.
+     * @param string $newId        The new item ID.
+     * @param string $providerName The MetaModel table name.
+     *
+     * @return PostDuplicateModelEvent
+     */
+    private function buildEvent(
+        string $sourceId,
+        string $newId,
+        string $providerName = 'mm_test'
+    ): PostDuplicateModelEvent {
+        $environment = $this->getMockForAbstractClass(EnvironmentInterface::class);
+
+        $sourceModel = $this->getMockForAbstractClass(ModelInterface::class);
+        $sourceModel->method('getId')->willReturn($sourceId);
+
+        $newModel = $this->getMockForAbstractClass(ModelInterface::class);
+        $newModel->method('getId')->willReturn($newId);
+        $newModel->method('getProviderName')->willReturn($providerName);
+
+        return new PostDuplicateModelEvent($environment, $newModel, $sourceModel);
+    }
+
+    /**
+     * Build a CopyTranslatedData listener with the given MetaModel (or null for "not found").
+     *
+     * @param IMetaModel|null $metaModel The MetaModel to return from factory, or null.
+     * @param string          $providerName The provider name used for factory lookup.
+     *
+     * @return CopyTranslatedData
+     */
+    private function buildListener(?IMetaModel $metaModel, string $providerName = 'mm_test'): CopyTranslatedData
+    {
+        /** @var IFactory&MockObject $factory */
+        $factory = $this->getMockForAbstractClass(IFactory::class);
+        $factory->method('getMetaModel')->with($providerName)->willReturn($metaModel);
+
+        return new CopyTranslatedData($factory);
+    }
+
+    /**
+     * Nothing happens when source and new ID are identical.
+     */
+    public function testHandleDoesNothingWhenIdsAreEqual(): void
+    {
+        /** @var ITranslatedMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(ITranslatedMetaModel::class);
+        $metaModel->expects(self::never())->method('getLanguages');
+
+        $listener = $this->buildListener($metaModel);
+        $listener->handle($this->buildEvent('42', '42'));
+    }
+
+    /**
+     * Nothing happens when source ID is empty.
+     */
+    public function testHandleDoesNothingWhenSourceIdIsEmpty(): void
+    {
+        /** @var ITranslatedMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(ITranslatedMetaModel::class);
+        $metaModel->expects(self::never())->method('getLanguages');
+
+        $listener = $this->buildListener($metaModel);
+        $listener->handle($this->buildEvent('', '99'));
+    }
+
+    /**
+     * Nothing happens when new ID is empty.
+     */
+    public function testHandleDoesNothingWhenNewIdIsEmpty(): void
+    {
+        /** @var ITranslatedMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(ITranslatedMetaModel::class);
+        $metaModel->expects(self::never())->method('getLanguages');
+
+        $listener = $this->buildListener($metaModel);
+        $listener->handle($this->buildEvent('42', ''));
+    }
+
+    /**
+     * Nothing happens when the MetaModel does not implement ITranslatedMetaModel.
+     */
+    public function testHandleDoesNothingForNonTranslatedMetaModel(): void
+    {
+        /** @var IMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(IMetaModel::class);
+        $metaModel->expects(self::never())->method('getAttributes');
+
+        $listener = $this->buildListener($metaModel);
+        $listener->handle($this->buildEvent('1', '2'));
+    }
+
+    /**
+     * Attributes that only implement ITranslated (not ITranslatedWithFallbackControl) are skipped.
+     */
+    public function testHandleSkipsAttributesWithoutFallbackControlInterface(): void
+    {
+        /** @var ITranslated&MockObject $attribute */
+        $attribute = $this->getMockForAbstractClass(ITranslated::class);
+        $attribute->expects(self::never())->method('setTranslatedDataFor');
+
+        /** @var ITranslatedMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(ITranslatedMetaModel::class);
+        $metaModel->method('getLanguages')->willReturn(['de', 'en']);
+        $metaModel->method('getAttributes')->willReturn([$attribute]);
+
+        $listener = $this->buildListener($metaModel);
+        $listener->handle($this->buildEvent('1', '2'));
+    }
+
+    /**
+     * Languages for which the attribute holds no data are skipped (applyTranslatedDataFor not called).
+     */
+    public function testHandleSkipsLanguagesWithNoData(): void
+    {
+        /** @var ITranslatedWithFallbackControl&MockObject $attribute */
+        $attribute = $this->getMockForAbstractClass(ITranslatedWithFallbackControl::class);
+        $attribute->method('getTranslatedDataForWithoutFallback')->willReturn([]);
+        $attribute->expects(self::never())->method('applyTranslatedDataFor');
+
+        /** @var ITranslatedMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(ITranslatedMetaModel::class);
+        $metaModel->method('getLanguages')->willReturn(['de', 'en']);
+        $metaModel->method('getAttributes')->willReturn([$attribute]);
+
+        $listener = $this->buildListener($metaModel);
+        $listener->handle($this->buildEvent('1', '2'));
+    }
+
+    /**
+     * Happy path: for each language and attribute with data, applyTranslatedDataFor is called with the new ID.
+     */
+    public function testHandleCopiesDataForAllLanguages(): void
+    {
+        $sourceId = '10';
+        $newId    = '99';
+
+        $dataDE = ['item_id' => $sourceId, 'langcode' => 'de', 'value' => 'Hallo'];
+        $dataEN = ['item_id' => $sourceId, 'langcode' => 'en', 'value' => 'Hello'];
+
+        /** @var ITranslatedWithFallbackControl&MockObject $attribute */
+        $attribute = $this->getMockForAbstractClass(ITranslatedWithFallbackControl::class);
+        $attribute->method('getTranslatedDataForWithoutFallback')->willReturnMap([
+            [[$sourceId], 'de', [$sourceId => $dataDE]],
+            [[$sourceId], 'en', [$sourceId => $dataEN]],
+        ]);
+
+        $attribute->expects(self::exactly(2))->method('applyTranslatedDataFor')->willReturnCallback(
+            static function (array $arrValues, string $lang) use ($newId, $dataDE, $dataEN): void {
+                self::assertArrayHasKey($newId, $arrValues, "New ID must be the array key for lang={$lang}");
+                if ('de' === $lang) {
+                    self::assertSame($dataDE, $arrValues[$newId]);
+                } else {
+                    self::assertSame($dataEN, $arrValues[$newId]);
+                }
+            }
+        );
+
+        /** @var ITranslatedMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(ITranslatedMetaModel::class);
+        $metaModel->method('getLanguages')->willReturn(['de', 'en']);
+        $metaModel->method('getAttributes')->willReturn([$attribute]);
+
+        $listener = $this->buildListener($metaModel);
+        $listener->handle($this->buildEvent($sourceId, $newId));
+    }
+
+    /**
+     * Only languages that actually have data are saved; others are silently skipped.
+     */
+    public function testHandleCopiesOnlyLanguagesWithActualData(): void
+    {
+        $sourceId = '5';
+        $newId    = '7';
+
+        $dataDE = ['item_id' => $sourceId, 'langcode' => 'de', 'value' => 'Hallo'];
+
+        /** @var ITranslatedWithFallbackControl&MockObject $attribute */
+        $attribute = $this->getMockForAbstractClass(ITranslatedWithFallbackControl::class);
+        $attribute->method('getTranslatedDataForWithoutFallback')->willReturnMap([
+            [[$sourceId], 'de', [$sourceId => $dataDE]],
+            [[$sourceId], 'en', []],
+        ]);
+
+        $attribute->expects(self::once())->method('applyTranslatedDataFor')
+            ->with([$newId => $dataDE], 'de');
+
+        /** @var ITranslatedMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(ITranslatedMetaModel::class);
+        $metaModel->method('getLanguages')->willReturn(['de', 'en']);
+        $metaModel->method('getAttributes')->willReturn([$attribute]);
+
+        $listener = $this->buildListener($metaModel);
+        $listener->handle($this->buildEvent($sourceId, $newId));
+    }
+
+    /**
+     * Multiple attributes per language are each handled independently.
+     */
+    public function testHandleProcessesMultipleAttributes(): void
+    {
+        $sourceId = '3';
+        $newId    = '8';
+
+        $data1 = ['item_id' => $sourceId, 'langcode' => 'de', 'value' => 'Attr1'];
+        $data2 = ['item_id' => $sourceId, 'langcode' => 'de', 'value' => 'Attr2'];
+
+        /** @var ITranslatedWithFallbackControl&MockObject $attribute1 */
+        $attribute1 = $this->getMockForAbstractClass(ITranslatedWithFallbackControl::class);
+        $attribute1->method('getTranslatedDataForWithoutFallback')->willReturn([$sourceId => $data1]);
+        $attribute1->expects(self::once())->method('applyTranslatedDataFor')->with([$newId => $data1], 'de');
+
+        /** @var ITranslatedWithFallbackControl&MockObject $attribute2 */
+        $attribute2 = $this->getMockForAbstractClass(ITranslatedWithFallbackControl::class);
+        $attribute2->method('getTranslatedDataForWithoutFallback')->willReturn([$sourceId => $data2]);
+        $attribute2->expects(self::once())->method('applyTranslatedDataFor')->with([$newId => $data2], 'de');
+
+        /** @var ITranslatedMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(ITranslatedMetaModel::class);
+        $metaModel->method('getLanguages')->willReturn(['de']);
+        $metaModel->method('getAttributes')->willReturn([$attribute1, $attribute2]);
+
+        $listener = $this->buildListener($metaModel);
+        $listener->handle($this->buildEvent($sourceId, $newId));
+    }
+}
diff --git a/tests/DcGeneral/Events/MetaModel/ResetLanguageAfterDuplicateTest.php b/tests/DcGeneral/Events/MetaModel/ResetLanguageAfterDuplicateTest.php
new file mode 100644
index 000000000..0fe76e54e
--- /dev/null
+++ b/tests/DcGeneral/Events/MetaModel/ResetLanguageAfterDuplicateTest.php
@@ -0,0 +1,174 @@
+<?php
+
+/**
+ * This file is part of MetaModels/core.
+ *
+ * (c) 2012-2026 The MetaModels team.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * This project is provided in good faith and hope to be usable by anyone.
+ *
+ * @package    MetaModels/core
+ * @author     Ingolf Steinhardt <info@e-spin.de>
+ * @copyright  2012-2026 The MetaModels team.
+ * @license    https://github.com/MetaModels/core/blob/master/LICENSE LGPL-3.0-or-later
+ * @filesource
+ */
+
+namespace MetaModels\Test\DcGeneral\Events\MetaModel;
+
+use ContaoCommunityAlliance\DcGeneral\Data\ModelInterface;
+use ContaoCommunityAlliance\DcGeneral\EnvironmentInterface;
+use ContaoCommunityAlliance\DcGeneral\Event\PostDuplicateModelEvent;
+use ContaoCommunityAlliance\DcGeneral\SessionStorageInterface;
+use MetaModels\DcGeneral\Events\MetaModel\ResetLanguageAfterDuplicate;
+use MetaModels\IFactory;
+use MetaModels\IMetaModel;
+use MetaModels\ITranslatedMetaModel;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \MetaModels\DcGeneral\Events\MetaModel\ResetLanguageAfterDuplicate
+ */
+class ResetLanguageAfterDuplicateTest extends TestCase
+{
+    /**
+     * Build a PostDuplicateModelEvent for the given provider name.
+     *
+     * @param string $providerName The MetaModel table name.
+     * @param SessionStorageInterface $sessionStorage The session storage mock.
+     *
+     * @return PostDuplicateModelEvent
+     */
+    private function buildEvent(string $providerName, SessionStorageInterface $sessionStorage): PostDuplicateModelEvent
+    {
+        /** @var SessionStorageInterface&MockObject $sessionStorage */
+        $environment = $this->getMockForAbstractClass(EnvironmentInterface::class);
+        $environment->method('getSessionStorage')->willReturn($sessionStorage);
+
+        $sourceModel = $this->getMockForAbstractClass(ModelInterface::class);
+        $sourceModel->method('getId')->willReturn('1');
+
+        $newModel = $this->getMockForAbstractClass(ModelInterface::class);
+        $newModel->method('getId')->willReturn('2');
+        $newModel->method('getProviderName')->willReturn($providerName);
+
+        return new PostDuplicateModelEvent($environment, $newModel, $sourceModel);
+    }
+
+    /**
+     * Build a ResetLanguageAfterDuplicate listener that returns the given MetaModel from the factory.
+     *
+     * @param IMetaModel|null $metaModel The MetaModel to return, or null.
+     * @param string          $providerName The provider name used for factory lookup.
+     *
+     * @return ResetLanguageAfterDuplicate
+     */
+    private function buildListener(
+        ?IMetaModel $metaModel,
+        string $providerName = 'mm_test'
+    ): ResetLanguageAfterDuplicate {
+        /** @var IFactory&MockObject $factory */
+        $factory = $this->getMockForAbstractClass(IFactory::class);
+        $factory->method('getMetaModel')->with($providerName)->willReturn($metaModel);
+
+        return new ResetLanguageAfterDuplicate($factory);
+    }
+
+    /**
+     * Nothing happens when the MetaModel is not a translated MetaModel.
+     */
+    public function testHandleDoesNothingForNonTranslatedMetaModel(): void
+    {
+        /** @var SessionStorageInterface&MockObject $sessionStorage */
+        $sessionStorage = $this->getMockForAbstractClass(SessionStorageInterface::class);
+        $sessionStorage->expects(self::never())->method('set');
+
+        /** @var IMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(IMetaModel::class);
+
+        $listener = $this->buildListener($metaModel);
+        $listener->handle($this->buildEvent('mm_test', $sessionStorage));
+    }
+
+    /**
+     * Nothing happens when the MetaModel cannot be found.
+     */
+    public function testHandleDoesNothingWhenMetaModelNotFound(): void
+    {
+        /** @var SessionStorageInterface&MockObject $sessionStorage */
+        $sessionStorage = $this->getMockForAbstractClass(SessionStorageInterface::class);
+        $sessionStorage->expects(self::never())->method('set');
+
+        $listener = $this->buildListener(null);
+        $listener->handle($this->buildEvent('mm_test', $sessionStorage));
+    }
+
+    /**
+     * The fallback language is written into the session for the provider name.
+     */
+    public function testHandleWritesFallbackLanguageToSession(): void
+    {
+        $providerName    = 'mm_test';
+        $fallbackLanguage = 'de';
+
+        /** @var SessionStorageInterface&MockObject $sessionStorage */
+        $sessionStorage = $this->getMockForAbstractClass(SessionStorageInterface::class);
+        $sessionStorage->method('get')->with('dc_general')->willReturn([]);
+        $sessionStorage
+            ->expects(self::once())
+            ->method('set')
+            ->with(
+                'dc_general',
+                self::callback(static function (array $session) use ($providerName, $fallbackLanguage): bool {
+                    return ($session['ml_support'][$providerName] ?? null) === $fallbackLanguage;
+                })
+            );
+
+        /** @var ITranslatedMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(ITranslatedMetaModel::class);
+        $metaModel->method('getMainLanguage')->willReturn($fallbackLanguage);
+
+        $listener = $this->buildListener($metaModel, $providerName);
+        $listener->handle($this->buildEvent($providerName, $sessionStorage));
+    }
+
+    /**
+     * Existing session data is preserved; only the ml_support entry for the provider is overwritten.
+     */
+    public function testHandlePreservesExistingSessionData(): void
+    {
+        $providerName    = 'mm_news';
+        $fallbackLanguage = 'en';
+
+        /** @var SessionStorageInterface&MockObject $sessionStorage */
+        $sessionStorage = $this->getMockForAbstractClass(SessionStorageInterface::class);
+        $sessionStorage->method('get')->with('dc_general')->willReturn([
+            'ml_support' => ['mm_other' => 'fr'],
+            'some_key'   => 'some_value',
+        ]);
+        $sessionStorage
+            ->expects(self::once())
+            ->method('set')
+            ->with(
+                'dc_general',
+                self::callback(
+                    static function (array $session) use ($providerName, $fallbackLanguage): bool {
+                        return ($session['ml_support'][$providerName] ?? null) === $fallbackLanguage
+                            && ($session['ml_support']['mm_other'] ?? null) === 'fr'
+                            && ($session['some_key'] ?? null) === 'some_value';
+                    }
+                )
+            );
+
+        /** @var ITranslatedMetaModel&MockObject $metaModel */
+        $metaModel = $this->getMockForAbstractClass(ITranslatedMetaModel::class);
+        $metaModel->method('getMainLanguage')->willReturn($fallbackLanguage);
+
+        $listener = $this->buildListener($metaModel, $providerName);
+        $listener->handle($this->buildEvent($providerName, $sessionStorage));
+    }
+}