diff --git a/src/ResponseType.php b/src/ResponseType.php
index da9da47..164a32d 100644
--- a/src/ResponseType.php
+++ b/src/ResponseType.php
@@ -135,6 +135,14 @@ public static function getAll(): array {
 				null,
 				null,
 			),
+			new ResponseType(
+				'StreamTraversableResponse',
+				false,
+				false,
+				null,
+				null,
+				null,
+			),
 			new ResponseType(
 				'TemplateResponse',
 				false,
diff --git a/tests/lib/Controller/OpenMetricsController.php b/tests/lib/Controller/OpenMetricsController.php
new file mode 100644
index 0000000..caba1e9
--- /dev/null
+++ b/tests/lib/Controller/OpenMetricsController.php
@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Notifications\Controller;
+
+use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\Attribute\ApiRoute;
+use OCP\AppFramework\OCSController;
+
+class OpenMetricsController extends OCSController {
+	/**
+	 * Use StreamTraversableResponse response type
+	 *
+	 * @return StreamTraversableResponse<Http::STATUS_OK, list<empty>, array{}>
+	 *
+	 * 200: Export OK
+	 */
+	#[ApiRoute(verb: 'GET', url: '/openmetrics')]
+	public function export(): StreamTraversableResponse {
+		return new StreamTraversableResponse($this->generator());
+	}
+
+	private function generator(): \Generator {
+		yield from [];
+	}
+}