diff --git a/frontend/packages/dashboard/src/dashboard.css b/frontend/packages/dashboard/src/dashboard.css
index 0c3231a9..0bc94eab 100644
--- a/frontend/packages/dashboard/src/dashboard.css
+++ b/frontend/packages/dashboard/src/dashboard.css
@@ -830,6 +830,44 @@ code {
   font-size: 0.8em;
   white-space: pre-wrap;
 }
+
+/* #575: cancel-X for queued rebuild_queue entries. Quiet by default
+   (sits at the far right via margin-left: auto), lights red on hover.
+   Renders only when `state === 'queued'` per renderQueueEntry's
+   guard — Running / terminal rows don't get the affordance. Mirrors
+   the side-panel-close glyph shape (✗) without the full B6N-style
+   `btn-deny` width so it stays unobtrusive in a list row. */
+.rqe-cancel {
+  margin-left: auto;
+}
+.rqe-cancel-btn {
+  background: transparent;
+  border: 1px solid var(--purple-dim);
+  color: var(--muted);
+  border-radius: 999px;
+  width: 1.6em;
+  height: 1.6em;
+  font-size: 0.85em;
+  line-height: 1;
+  padding: 0;
+  cursor: pointer;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  transition: color 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
+}
+.rqe-cancel-btn:hover:not(:disabled),
+.rqe-cancel-btn:focus-visible {
+  color: var(--red);
+  border-color: var(--red);
+  box-shadow: 0 0 8px -2px var(--red);
+  outline: none;
+}
+.rqe-cancel-btn:disabled {
+  opacity: 0.5;
+  cursor: default;
+}
+
 .history-note {
   margin-left: 1.8em;
   margin-top: 0.2em;
diff --git a/frontend/packages/dashboard/src/tabs.js b/frontend/packages/dashboard/src/tabs.js
index aa46c5d2..149ef514 100644
--- a/frontend/packages/dashboard/src/tabs.js
+++ b/frontend/packages/dashboard/src/tabs.js
@@ -1839,6 +1839,34 @@ window.marked = marked;
     if (entry.error) {
       li.append(el('pre', { class: 'rqe-error', title: entry.error }, truncate(entry.error, 200)));
     }
+    // #575: cancel-X for queued entries. Backend
+    // `POST /api/rebuild-queue/{id}/cancel` is already implemented
+    // (refuses Running / terminal entries); we surface it only on
+    // `queued` rows here so the operator never sees a dead button.
+    // Uses the same `data-async` form + `data-confirm` pattern as the
+    // reminder cancel, so the global async-form handler takes care
+    // of POST + spinner + error toast. A successful cancel flips
+    // `state` from `queued` → `cancelled` via the live
+    // RebuildQueueChanged snapshot and the row re-renders without
+    // this button.
+    if (entry.state === 'queued') {
+      const cancelForm = el('form', {
+        method: 'POST',
+        action: '/api/rebuild-queue/' + entry.id + '/cancel',
+        class: 'inline rqe-cancel',
+        'data-async': '',
+        'data-confirm':
+          `cancel ${entry.kind} for \`${entry.agent}\` (queue id ${entry.id})? ` +
+          `the row drops from the queue and never runs. running / done / failed entries can't be cancelled this way.`,
+      });
+      cancelForm.append(el('button', {
+        type: 'submit',
+        class: 'rqe-cancel-btn',
+        title: 'cancel this queued ' + entry.kind,
+        'aria-label': 'cancel queued ' + entry.kind + ' for ' + entry.agent,
+      }, '✗'));
+      li.append(cancelForm);
+    }
     return li;
   }