diff --git a/src/RAG/VectorStore/PhpVectorStore.php b/src/RAG/VectorStore/PhpVectorStore.php
new file mode 100644
index 00000000..c91a3feb
--- /dev/null
+++ b/src/RAG/VectorStore/PhpVectorStore.php
@@ -0,0 +1,154 @@
+<?php
+
+declare(strict_types=1);
+
+namespace NeuronAI\RAG\VectorStore;
+
+use NeuronAI\RAG\Document;
+
+/**
+ * PHP Vector Store — zero-dependency local vector store.
+ *
+ * Binary Float32 storage with Matryoshka multi-stage search and Int8 quantization.
+ * No external services, no C extensions, no SQLite — pure PHP.
+ *
+ * Requires: mauricioperera/php-vector-store (composer require mauricioperera/php-vector-store)
+ *
+ * @see https://github.com/MauricioPerera/php-vector-store
+ */
+class PhpVectorStore implements VectorStoreInterface
+{
+    private \PHPVectorStore\VectorStore|\PHPVectorStore\QuantizedStore $store;
+
+    /**
+     * @param string $directory   Path to store vector files.
+     * @param int    $dimensions  Vector dimensions (384 recommended for Matryoshka).
+     * @param string $collection  Collection name.
+     * @param int    $topK        Number of results for similarity search.
+     * @param bool   $quantized   Use Int8 quantization (4x smaller, <0.001 score drift).
+     * @param bool   $matryoshka  Use Matryoshka multi-stage search (3-5x faster).
+     * @param int[]  $stages      Matryoshka stages (auto-detected from dimensions if empty).
+     */
+    public function __construct(
+        protected string $directory,
+        protected int $dimensions = 384,
+        protected string $collection = 'documents',
+        protected int $topK = 4,
+        protected bool $quantized = true,
+        protected bool $matryoshka = true,
+        protected array $stages = [],
+    ) {
+        if (!class_exists(\PHPVectorStore\VectorStore::class)) {
+            throw new \RuntimeException(
+                'PHP Vector Store is not installed. Run: composer require mauricioperera/php-vector-store'
+            );
+        }
+
+        $this->store = $quantized
+            ? new \PHPVectorStore\QuantizedStore($directory, $dimensions)
+            : new \PHPVectorStore\VectorStore($directory, $dimensions);
+
+        if (empty($this->stages)) {
+            $this->stages = self::defaultStages($dimensions);
+        }
+    }
+
+    public function addDocument(Document $document): VectorStoreInterface
+    {
+        $this->store->set(
+            $this->collection,
+            (string) $document->getId(),
+            $document->getEmbedding(),
+            $this->documentToMeta($document),
+        );
+        $this->store->flush();
+        return $this;
+    }
+
+    public function addDocuments(array $documents): VectorStoreInterface
+    {
+        foreach ($documents as $document) {
+            $this->store->set(
+                $this->collection,
+                (string) $document->getId(),
+                $document->getEmbedding(),
+                $this->documentToMeta($document),
+            );
+        }
+        $this->store->flush();
+        return $this;
+    }
+
+    /**
+     * @deprecated Use deleteBy() instead.
+     */
+    public function deleteBySource(string $sourceType, string $sourceName): VectorStoreInterface
+    {
+        return $this->deleteBy($sourceType, $sourceName);
+    }
+
+    public function deleteBy(string $sourceType, ?string $sourceName = null): VectorStoreInterface
+    {
+        foreach ($this->store->ids($this->collection) as $id) {
+            $record = $this->store->get($this->collection, $id);
+            if (!$record) {
+                continue;
+            }
+
+            $meta = $record['metadata'] ?? [];
+            if (($meta['sourceType'] ?? '') !== $sourceType) {
+                continue;
+            }
+            if ($sourceName !== null && ($meta['sourceName'] ?? '') !== $sourceName) {
+                continue;
+            }
+
+            $this->store->remove($this->collection, $id);
+        }
+
+        $this->store->flush();
+        return $this;
+    }
+
+    public function similaritySearch(array $embedding): iterable
+    {
+        $results = $this->matryoshka
+            ? $this->store->matryoshkaSearch($this->collection, $embedding, $this->topK, $this->stages)
+            : $this->store->search($this->collection, $embedding, $this->topK);
+
+        $documents = [];
+
+        foreach ($results as $result) {
+            $meta = $result['metadata'] ?? [];
+
+            $document = new Document($meta['content'] ?? '');
+            $document->id = $result['id'];
+            $document->sourceType = $meta['sourceType'] ?? 'manual';
+            $document->sourceName = $meta['sourceName'] ?? 'manual';
+            $document->metadata = $meta['userMeta'] ?? [];
+            $document->setScore($result['score']);
+
+            $documents[] = $document;
+        }
+
+        return $documents;
+    }
+
+    private function documentToMeta(Document $document): array
+    {
+        return [
+            'content'    => $document->getContent(),
+            'sourceType' => $document->getSourceType(),
+            'sourceName' => $document->getSourceName(),
+            'userMeta'   => $document->metadata,
+        ];
+    }
+
+    private static function defaultStages(int $dim): array
+    {
+        if ($dim <= 128) return [$dim];
+        if ($dim <= 256) return [128, $dim];
+        if ($dim <= 384) return [128, 256, $dim];
+        return [128, 384, $dim];
+    }
+}