diff --git a/frontend/packages/dashboard/src/agent-menu/hive-agent-menu.js b/frontend/packages/dashboard/src/agent-menu/hive-agent-menu.js
index 54fe3b60..bfed9242 100644
--- a/frontend/packages/dashboard/src/agent-menu/hive-agent-menu.js
+++ b/frontend/packages/dashboard/src/agent-menu/hive-agent-menu.js
@@ -49,6 +49,13 @@ async function agentMenuPost(actionPath, name, body, graceful) {
 
 class HiveAgentMenu extends HTMLElement {
   connectedCallback() {
+    // Same reconnect-without-detach hazard as <hive-menu> (see its
+    // connectedCallback comment) — swarm.js's row cache can move an
+    // already-built <li> subtree without a real detach. Without this
+    // guard a reconnect would append a second <hive-menu> on top of the
+    // first, doubling the dropdown.
+    if (this._menu) return;
+
     const { c, forgeBase } = this._opts || {};
 
     const btn = el('button', {
diff --git a/frontend/packages/shared/src/hive-menu/hive-menu.js b/frontend/packages/shared/src/hive-menu/hive-menu.js
index 50d06625..53d8da8b 100644
--- a/frontend/packages/shared/src/hive-menu/hive-menu.js
+++ b/frontend/packages/shared/src/hive-menu/hive-menu.js
@@ -65,6 +65,16 @@ document.addEventListener('keydown', (e) => {
 
 class HiveMenu extends HTMLElement {
   connectedCallback() {
+    // A custom element's connectedCallback fires again on a same-document
+    // *move* (insertBefore/append repositioning an already-connected node
+    // runs the removal + insertion steps for its whole subtree), not just
+    // on a fresh mount — swarm.js's row-fingerprint cache reuses/reorders
+    // existing <li> subtrees, which can move an already-initialised
+    // <hive-menu> without ever detaching it from the document. Guard
+    // against re-running setup (attachShadow throws if the host already
+    // has a shadow root) on that reconnect.
+    if (this.shadowRoot) return;
+
     const { trigger, content } = this._opts || {};
     const root = attachShadowCss(this, hiveMenuCss);