Missing resolver added

app/code/Magento/CatalogGraphQl/Model/Resolver/Category/Products.php

@@ -65,7 +65,7 @@ public function resolve(
                 'eq' => $value['id']
             ]
         ];
-            $searchCriteria = $this->searchCriteriaBuilder->build($field->getName(), $args);
+        $searchCriteria = $this->searchCriteriaBuilder->build($field->getName(), $args);
         $searchCriteria->setCurrentPage($args['currentPage']);
         $searchCriteria->setPageSize($args['pageSize']);
         $searchResult = $this->filterQuery->getResult($searchCriteria, $info);

app/code/Magento/CatalogGraphQl/Model/Resolver/Category/ProductsCount.php

@@ -0,0 +1,70 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\CatalogGraphQl\Model\Resolver\Category;
+
+use Magento\Catalog\Model\Category;
+use Magento\Catalog\Model\Product\Visibility;
+use Magento\CatalogGraphQl\Model\Resolver\Products\DataProvider\Product\CollectionProcessor\StockProcessor;
+use Magento\Framework\Api\SearchCriteriaInterface;
+use Magento\Framework\GraphQl\Exception\GraphQlInputException;
+use Magento\Framework\GraphQl\Schema\Type\ResolveInfo;
+use Magento\Framework\GraphQl\Config\Element\Field;
+use Magento\Framework\GraphQl\Query\ResolverInterface;
+
+/**
+ * Retrieves products count for a category
+ */
+class ProductsCount implements ResolverInterface
+{
+    /**
+     * @var Visibility
+     */
+    private $catalogProductVisibility;
+
+    /**
+     * @var StockProcessor
+     */
+    private $stockProcessor;
+
+    /**
+     * @var SearchCriteriaInterface
+     */
+    private $searchCriteria;
+
+    /**
+     * @param Visibility $catalogProductVisibility
+     * @param SearchCriteriaInterface $searchCriteria
+     * @param StockProcessor $stockProcessor
+     */
+    public function __construct(
+        Visibility $catalogProductVisibility,
+        SearchCriteriaInterface $searchCriteria,
+        StockProcessor $stockProcessor
+    ) {
+        $this->catalogProductVisibility = $catalogProductVisibility;
+        $this->searchCriteria = $searchCriteria;
+        $this->stockProcessor = $stockProcessor;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null)
+    {
+        if (!isset($value['model'])) {
+            throw new GraphQlInputException(__('"model" value should be specified'));
+        }
+        /** @var Category $category */
+        $category = $value['model'];
+        $productsCollection = $category->getProductCollection();
+        $productsCollection->setVisibility($this->catalogProductVisibility->getVisibleInSiteIds());
+        $productsCollection = $this->stockProcessor->process($productsCollection, $this->searchCriteria, []);
+
+        return $productsCollection->getSize();
+    }
+}