[Store] Add IndexerInterface for better abstraction and testability

- Add IndexerInterface with index method for TextDocument processing
- Update Indexer class to implement IndexerInterface
- Update AiBundle to use IndexerInterface for dependency injection aliasing
- Update demo Embedder to use IndexerInterface instead of concrete class

Author: OskarStark

demo/src/Blog/Embedder.php

@@ -13,13 +13,13 @@
 
 use Symfony\AI\Store\Document\Metadata;
 use Symfony\AI\Store\Document\TextDocument;
-use Symfony\AI\Store\Indexer;
+use Symfony\AI\Store\IndexerInterface;
 
 final readonly class Embedder
 {
     public function __construct(
         private FeedLoader $loader,
-        private Indexer $indexer,
+        private IndexerInterface $indexer,
     ) {
     }
 

src/ai-bundle/src/AiBundle.php

@@ -67,6 +67,7 @@
 use Symfony\AI\Store\Bridge\Weaviate\Store as WeaviateStore;
 use Symfony\AI\Store\Document\Vectorizer;
 use Symfony\AI\Store\Indexer;
+use Symfony\AI\Store\IndexerInterface;
 use Symfony\AI\Store\StoreInterface;
 use Symfony\Component\Config\Definition\Configurator\DefinitionConfigurator;
 use Symfony\Component\DependencyInjection\Attribute\Target;
@@ -144,7 +145,7 @@ public function loadExtension(array $config, ContainerConfigurator $container, C
             $this->processIndexerConfig($indexerName, $indexer, $builder);
         }
         if (1 === \count($config['indexer']) && isset($indexerName)) {
-            $builder->setAlias(Indexer::class, 'ai.indexer.'.$indexerName);
+            $builder->setAlias(IndexerInterface::class, 'ai.indexer.'.$indexerName);
         }
 
         $builder->registerAttributeForAutoconfiguration(AsTool::class, static function (ChildDefinition $definition, AsTool $attribute): void {

src/store/src/Indexer.php

@@ -21,7 +21,7 @@
  *
  * @author Christopher Hertel <[email protected]>
  */
-final readonly class Indexer
+final readonly class Indexer implements IndexerInterface
 {
     public function __construct(
         private Vectorizer $vectorizer,

src/store/src/IndexerInterface.php

@@ -0,0 +1,28 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\AI\Store;
+
+use Symfony\AI\Store\Document\TextDocument;
+
+/**
+ * Converts a collection of TextDocuments into VectorDocuments and pushes them to a store implementation.
+ *
+ * @author Oskar Stark <[email protected]>
+ */
+interface IndexerInterface
+{
+    /**
+     * @param TextDocument|iterable<TextDocument> $documents
+     * @param int                                 $chunkSize number of documents to vectorize and store in one batch
+     */
+    public function index(TextDocument|iterable $documents, int $chunkSize = 50): void;
+}