diff --git a/lib/hyperscript/integration.sx b/lib/hyperscript/integration.sx
index 147d7350..e989d2ea 100644
--- a/lib/hyperscript/integration.sx
+++ b/lib/hyperscript/integration.sx
@@ -82,6 +82,7 @@
         (and src (not (= src prev)))
         (dom-set-data el "hs-script" src)
         (dom-set-data el "hs-active" true)
+        (dom-set-attr el "data-hyperscript-powered" "true")
         (let ((handler (hs-handler src))) (handler el))))))
 
 ;; ── Boot: scan entire document ──────────────────────────────────
diff --git a/shared/static/wasm/sx/hs-integration.sx b/shared/static/wasm/sx/hs-integration.sx
index 147d7350..e989d2ea 100644
--- a/shared/static/wasm/sx/hs-integration.sx
+++ b/shared/static/wasm/sx/hs-integration.sx
@@ -82,6 +82,7 @@
         (and src (not (= src prev)))
         (dom-set-data el "hs-script" src)
         (dom-set-data el "hs-active" true)
+        (dom-set-attr el "data-hyperscript-powered" "true")
         (let ((handler (hs-handler src))) (handler el))))))
 
 ;; ── Boot: scan entire document ──────────────────────────────────