onChildrenDeleted method

@override void onChildrenDeleted(Set<String> nodeIds)

Called when child nodes are deleted from the graph.

Receives all deleted node IDs, allowing the grouping node to update its internal state (e.g., remove them from membership).

Implementation

@override
void onChildrenDeleted(Set<String> nodeIds) {
  final removed = _nodeIds.intersection(nodeIds);
  if (removed.isEmpty) return;
  runInAction(() => _nodeIds.removeAll(removed));

  // For explicit behavior, refit to remaining nodes
  if (behavior == GroupBehavior.explicit &&
      _nodeIds.isNotEmpty &&
      groupContext != null) {
    fitToNodes(groupContext!.getNode);
  }
}