diff --git a/src/Contracts/SessionIdGeneratorInterface.php b/src/Contracts/SessionIdGeneratorInterface.php
new file mode 100644
index 0000000..7e0fab8
--- /dev/null
+++ b/src/Contracts/SessionIdGeneratorInterface.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpMcp\Server\Contracts;
+
+interface SessionIdGeneratorInterface
+{
+    /**
+     * Generate a unique session ID.
+     *
+     * @return string The generated session ID
+     */
+    public function generateId(): string;
+
+    /**
+     * Called when a session is initialized
+     *
+     * @param string $sessionId The session ID
+     */
+    public function onSessionInitialized(string $sessionId): void;
+}