diff --git a/public/app.js b/public/app.js
index 2dcade8..1478d7b 100644
--- a/public/app.js
+++ b/public/app.js
@@ -89,6 +89,7 @@ document.addEventListener('DOMContentLoaded', function() {
     // ── Robot.json + History ─────────────────────────────────────────────────
 
     let robotJsonActive = 'current';
+    let robotJsonLastSerialized = null;
 
     function renderJsonTree(data, container) {
         container.innerHTML = '';
@@ -123,9 +124,13 @@ document.addEventListener('DOMContentLoaded', function() {
         fetch(url)
             .then(res => res.ok ? res.json() : Promise.reject(res.status))
             .then(data => {
+                const serialized = JSON.stringify(data);
                 document.getElementById('robotJsonLabel').textContent =
                     robotJsonActive === 'current' ? '(aktuell)' : `(${robotJsonActive})`;
-                renderJsonTree(data, document.getElementById('robotJsonTree'));
+                if (serialized !== robotJsonLastSerialized) {
+                    robotJsonLastSerialized = serialized;
+                    renderJsonTree(data, document.getElementById('robotJsonTree'));
+                }
             })
             .catch(err => {
                 document.getElementById('robotJsonTree').textContent = `Fehler: ${err}`;
@@ -134,6 +139,7 @@ document.addEventListener('DOMContentLoaded', function() {
 
     function setHistoryActive(ts) {
         robotJsonActive = ts;
+        robotJsonLastSerialized = null; // Neuaufbau erzwingen beim Snapshot-Wechsel
         updateRobotJson();
         document.querySelectorAll('#robotHistoryList li').forEach(l => {
             l.classList.toggle('rh-active', l.dataset.ts === ts);