maybe this one works

src/env.d.ts

@@ -0,0 +1,10 @@
+// src/env.d.ts
+
+/// <reference path="../.astro/types.d.ts" />
+/// <reference types="astro/client" />
+
+type Runtime = import("@astrojs/cloudflare").Runtime<Env>;
+
+declare namespace App {
+	interface Locals extends Runtime {}
+}