When a node is collapsed the expand/collapse button shows a +N badge indicating the total number of hidden descendants. The badge disappears when the node is expanded again.
Bob and Jane are pre-collapsed — click their buttons to toggle.
Custom green badge. Click to expand/collapse.
Badge only shown when ≥ 3 nodes hidden. Bob (+5) shows; Jane (+2) does not.
No badge rendered even when collapsed.
Red badge via --apex-tree-badge-bg and --apex-tree-badge-color.
Badge appears to the left of the collapse button.