diff --git a/diagnostic/server.js b/diagnostic/server.js
index 71d5009..2eed569 100644
--- a/diagnostic/server.js
+++ b/diagnostic/server.js
@@ -1602,7 +1602,16 @@ const htmlPath = path.join(__dirname, "index.html");
 
 const server = http.createServer((req, res) => {
   if (req.url === "/" || req.url === "/index.html") {
-    res.writeHead(200, { "Content-Type": "text/html; charset=utf-8" });
+    // no-store: das Dashboard ist eine Single-HTML-App die bei jedem Deploy
+    // neue Inline-JS/CSS bekommt. Ohne Cache-Header servierte der Browser die
+    // alte Version trotz Reload (neue Features tauchten erst nach Hard-Reload
+    // auf) — genau das Symptom „ich seh den Button nicht".
+    res.writeHead(200, {
+      "Content-Type": "text/html; charset=utf-8",
+      "Cache-Control": "no-store, no-cache, must-revalidate",
+      "Pragma": "no-cache",
+      "Expires": "0",
+    });
     res.end(fs.readFileSync(htmlPath, "utf-8"));
   } else if (req.url === "/api/state") {
     res.writeHead(200, { "Content-Type": "application/json" });