Fix incorrect grouped product qty returned in GraphQL due to hydration overwriting link attributes

app/code/Magento/Catalog/Test/Unit/Helper/ProductTestHelper.php

@@ -583,7 +583,7 @@ public function getData($key = '', $index = null)
         if (!is_array($this->data)) {
             $this->data = [];
         }
-        
+
         // Check if there's a callback set for getData
         if (isset($this->data['get_data_callback'])) {
             return call_user_func($this->data['get_data_callback'], $key);
@@ -594,17 +594,17 @@ public function getData($key = '', $index = null)
             return $this->data['product_data'] ?? [];
         }
         $productData = $this->data['product_data'] ?? [];
-        
+
         // If key doesn't exist, return null
         if (!isset($productData[$key])) {
             return null;
         }
-        
+
         // If index is provided and value is an array, return indexed value
         if ($index !== null && is_array($productData[$key])) {
             return $productData[$key][$index] ?? null;
         }
-        
+
         return $productData[$key];
     }
 
@@ -621,7 +621,7 @@ public function setData($key, $value = null): self
         if (!is_array($this->data)) {
             $this->data = [];
         }
-        
+
         // Use separate productData array for getData/setData to avoid conflicts
         if (!isset($this->data['product_data'])) {
             $this->data['product_data'] = [];
@@ -1624,4 +1624,26 @@ public function getCost()
     {
         return $this->getData('cost') ?? $this->cost;
     }
+
+    /**
+     * Get initial qty
+     *
+     * @return int|null
+     */
+    public function getInitialQty(): ?int
+    {
+        return $this->getData('initial_qty');
+    }
+
+    /**
+     * Set parent product id for tests.
+     *
+     * @param int|null $initialQty
+     * @return $this
+     */
+    public function setInitialQty(?int $initialQty)
+    {
+        $this->setData('initial_qty', $initialQty);
+        return $this;
+    }
 }

app/code/Magento/GroupedProduct/Model/Product/Link/ProductEntity/Converter.php

@@ -20,7 +20,7 @@ public function convert(\Magento\Catalog\Model\Product $product)
             'sku' => $product->getSku(),
             'position' => $product->getPosition(),
             'custom_attributes' => [
-                ['attribute_code' => 'qty', 'value' => $product->getQty()],
+                ['attribute_code' => 'qty', 'value' => $product->getInitialQty() ?? $product->getQty()],
             ]
         ];
     }

app/code/Magento/GroupedProduct/Model/Product/Type/Grouped.php

@@ -228,6 +228,7 @@ public function getAssociatedProducts($product)
             );
 
             foreach ($collection as $item) {
+                $item->setInitialQty($item->getQty());
                 $associatedProducts[] = $item;
             }
 

app/code/Magento/GroupedProduct/Test/Unit/Model/Product/Link/ConverterTest.php

@@ -0,0 +1,82 @@
+<?php
+/**
+ * Copyright 2025 Adobe
+ * All Rights Reserved.
+ */
+declare(strict_types=1);
+
+namespace Magento\GroupedProduct\Test\Unit\Model\Product\Link;
+
+use Magento\Catalog\Test\Unit\Helper\ProductTestHelper;
+use Magento\GroupedProduct\Model\Product\Link\ProductEntity\Converter;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Tests for Converter
+ *
+ * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
+ */
+class ConverterTest extends TestCase
+{
+    /**
+     * @var Converter
+     */
+    private Converter $converter;
+
+    protected function setUp(): void
+    {
+        $this->converter = new Converter();
+    }
+
+    public function testConvertUsesInitialQtyWhenAvailable(): void
+    {
+        $product = $this->createPartialMock(
+            ProductTestHelper::class,
+            ['getTypeId', 'getSku', 'getQty', 'getPosition', 'getInitialQty']
+        );
+
+        $product->method('getTypeId')->willReturn('simple');
+        $product->method('getSku')->willReturn('sku-123');
+        $product->method('getPosition')->willReturn(5);
+
+        // Qty override
+        $product->method('getInitialQty')->willReturn(10);
+        $product->method('getQty')->willReturn(2); // fallback should NOT be used
+
+        $result = $this->converter->convert($product);
+
+        $this->assertSame('simple', $result['type']);
+        $this->assertSame('sku-123', $result['sku']);
+        $this->assertSame(5, $result['position']);
+
+        $this->assertSame(
+            [
+                ['attribute_code' => 'qty', 'value' => 10]
+            ],
+            $result['custom_attributes']
+        );
+    }
+
+    public function testConvertFallsBackToQtyIfInitialQtyIsNull(): void
+    {
+        $product = $this->createPartialMock(
+            ProductTestHelper::class,
+            ['getTypeId', 'getSku', 'getQty', 'getPosition', 'getInitialQty']
+        );
+
+        $product->method('getTypeId')->willReturn('simple');
+        $product->method('getSku')->willReturn('sku-456');
+        $product->method('getPosition')->willReturn(7);
+        $product->method('getInitialQty')->willReturn(null);
+        $product->method('getQty')->willReturn(3);
+
+        $result = $this->converter->convert($product);
+
+        $this->assertSame(
+            [
+                ['attribute_code' => 'qty', 'value' => 3]
+            ],
+            $result['custom_attributes']
+        );
+    }
+}

app/code/Magento/GroupedProduct/Test/Unit/Model/Product/Type/GroupedTest.php

@@ -7,6 +7,7 @@
 
 namespace Magento\GroupedProduct\Test\Unit\Model\Product\Type;
 
+use Magento\Catalog\Test\Unit\Helper\ProductTestHelper;
 use PHPUnit\Framework\Attributes\DataProvider;
 use Magento\Catalog\Model\Product;
 use Magento\Catalog\Model\Product\Attribute\Source\Status;
@@ -22,6 +23,7 @@
 use Magento\GroupedProduct\Model\Product\Type\Grouped;
 use Magento\GroupedProduct\Model\ResourceModel\Product\Link;
 use Magento\MediaStorage\Helper\File\Storage\Database;
+use PHPUnit\Framework\MockObject\Exception;
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 use Psr\Log\LoggerInterface;
@@ -164,6 +166,58 @@ public function testGetAssociatedProducts(): void
         $this->assertEquals($associatedProducts, $this->_model->getAssociatedProducts($this->product));
     }
 
+    /**
+     * Verify get associated products with setting initial qty
+     *
+     * @return void
+     */
+    public function testGetAssociatedProductsSetsInitialQty(): void
+    {
+        $this->product->expects($this->atLeastOnce())
+            ->method('hasData')
+            ->willReturn(false);
+        $savedValue = null;
+        $this->product->expects($this->atLeastOnce())
+            ->method('setData')
+            ->willReturnCallback(function ($key, $value) use (&$savedValue) {
+                $savedValue = $value;
+                return null;
+            });
+        $this->product->expects($this->atLeastOnce())
+            ->method('getData')
+            ->willReturnCallback(function () use (&$savedValue) {
+                return $savedValue;
+            });
+        $itemMock = $this->createMock(ProductTestHelper::class);
+        $itemMock->expects($this->once())
+            ->method('getQty')
+            ->willReturn(10);
+        $itemMock->expects($this->once())
+            ->method('setInitialQty')
+            ->with(10);
+        $collectionMock = $this->createMock(Collection::class);
+        $collectionMock->method('addAttributeToSelect')->willReturnSelf();
+        $collectionMock->method('addFilterByRequiredOptions')->willReturnSelf();
+        $collectionMock->method('setPositionOrder')->willReturnSelf();
+        $collectionMock->method('addStoreFilter')->willReturnSelf();
+        $collectionMock->method('addAttributeToFilter')->willReturnSelf();
+        $collectionMock->method('setFlag')->willReturnSelf();
+        $collectionMock->method('setIsStrongMode')->willReturnSelf();
+        $collectionMock->expects($this->once())
+            ->method('getIterator')
+            ->willReturn(new \ArrayIterator([$itemMock]));
+        $linkMock = $this->createMock(Product\Link::class);
+        $linkMock->expects($this->once())
+            ->method('getProductCollection')
+            ->willReturn($collectionMock);
+        $this->product->expects($this->once())
+            ->method('getLinkInstance')
+            ->willReturn($linkMock);
+        $result = $this->_model->getAssociatedProducts($this->product);
+        $this->assertCount(1, $result);
+        $this->assertSame($itemMock, $result[0]);
+    }
+
     /**
      * Verify able to set status filter
      *