diff --git a/functions/api/auth/mobile/is-valid.ts b/functions/api/auth/mobile/is-valid.ts
new file mode 100644
index 0000000..bd0d726
--- /dev/null
+++ b/functions/api/auth/mobile/is-valid.ts
@@ -0,0 +1,7 @@
+import { jsonResponse } from "../../../common.js";
+
+export async function onRequestGet(context: RequestContext) {
+  return jsonResponse(
+    JSON.stringify({ valid: Boolean(context.data.current_user) }),
+  );
+}