Guard View surface tree traversal

webui/src/features/views/ViewsAdminPanel.tsx

@@ -1054,10 +1054,12 @@ function SurfaceSelector({
 
   function descendants(surfaceId: string): string[] {
     const result: string[] = [];
+    const visited = new Set([surfaceId]);
     const pending = [...(childrenByParent.get(surfaceId) ?? [])];
     while (pending.length) {
       const child = pending.shift();
-      if (!child) continue;
+      if (!child || visited.has(child.id)) continue;
+      visited.add(child.id);
       result.push(child.id);
       pending.push(...(childrenByParent.get(child.id) ?? []));
     }
@@ -1065,8 +1067,11 @@ function SurfaceSelector({
   }
 
   function withAncestors(next: Set<string>, surfaceId: string) {
+    const visited = new Set([surfaceId]);
     let current = byId.get(surfaceId);
     while (current?.parentId) {
+      if (visited.has(current.parentId)) break;
+      visited.add(current.parentId);
       next.add(current.parentId);
       current = byId.get(current.parentId);
     }