pub fn link_parent_child(world: &mut World, child: EntityId, parent: EntityId)Expand description
Links child under parent, maintaining both halves of the hierarchy
edge — the Parent back-reference and the parent’s Children list.
Every SceneCommand::SetParent handler goes through this. They used to add
only Parent and rely on a serialized Children component to supply the
forward list, which quietly loaded the source world’s entity ids; now that
Children is Derived and no longer persisted, the inverse index has to be
rebuilt here instead. Mirrors the invariant GameWorld::set_parent enforces
for live edits.