diff --git a/hosts/ocaml/browser/test_wasm_native.js b/hosts/ocaml/browser/test_wasm_native.js
index f8f3aa04..68ce9e98 100644
--- a/hosts/ocaml/browser/test_wasm_native.js
+++ b/hosts/ocaml/browser/test_wasm_native.js
@@ -219,7 +219,12 @@ async function main() {
   // The actual reactive-spread pattern: module-loaded function creates effect
   // that calls cek-call on a render-fn returning a spread, then applies attrs.
   assert('reactive-spread from module',
-    K.eval('(let ((el (dom-create-element "div" nil)) (d (list))) (with-island-scope (fn (x) (append! d x)) (fn () (reactive-spread el (fn () (~cssx/tw :tokens "text-center"))))) (host-get el "className"))'),
+    K.eval('(let ((el (dom-create-element "div" nil)) (d (list))) (with-island-scope (fn (x) (append! d x)) (fn () (reactive-spread el (fn () (~cssx/tw :tokens "text-center"))))) (dom-get-attr el "class"))'),
+    'sx-text-center');
+
+  // Full hydration pattern: render-to-dom with CSSX inside island scope
+  assertIncludes('render-to-dom CSSX in island scope',
+    K.eval("(host-get (let ((d (list))) (with-island-scope (fn (x) (append! d x)) (fn () (render-to-dom '(div (~cssx/tw :tokens \"text-center font-bold\") \"hello\") (global-env) nil)))) \"outerHTML\")"),
     'sx-text-center');
 
   // Reactive: signal update propagation