diff --git a/engine/src/main/resources/org/archive/crawler/restlet/js/heritrix-ui.js b/engine/src/main/resources/org/archive/crawler/restlet/js/heritrix-ui.js
index 5c396cb6..a42dfe5f 100644
--- a/engine/src/main/resources/org/archive/crawler/restlet/js/heritrix-ui.js
+++ b/engine/src/main/resources/org/archive/crawler/restlet/js/heritrix-ui.js
@@ -1,6 +1,33 @@
 (function () {
   "use strict";
 
+  // Implement invoker commands for older browsers like Firefox ESR
+  // This can likely be removed in April 2027 when ESR 115 ends
+  if (!("command" in HTMLButtonElement.prototype &&
+        "commandForElement" in HTMLButtonElement.prototype)) {
+    // Delegate so buttons parsed after this script (including dialog close buttons) work.
+    document.addEventListener("click", function (event) {
+      var button = event.target.closest("button[command][commandfor]");
+      if (!button || button.matches(":disabled") || event.defaultPrevented) {
+        return;
+      }
+
+      var target = document.getElementById(button.getAttribute("commandfor"));
+      if (!target || target.localName !== "dialog") {
+        return;
+      }
+
+      var command = button.getAttribute("command").toLowerCase();
+      if (command === "show-modal" && typeof target.showModal === "function") {
+        event.preventDefault();
+        target.showModal();
+      } else if (command === "close" && typeof target.close === "function") {
+        event.preventDefault();
+        target.close();
+      }
+    });
+  }
+
   document.addEventListener("click", function (event) {
     var topbarToggle = event.target.closest(".top-bar .toggle-topbar a");
     if (topbarToggle) {