Module refgraph 

RefGraph — reverse-reference index over a StepModel.

The model stores references in the forward direction: an entity points to what it uses. Many read queries want the inverse (“what references this entity?”) — the scene handles need it to walk an assembly or a shape upward. StepModel::ref_graph builds the index by inverting every entity’s outgoing references; the enumeration underneath is generated, so no entity type is missed.

Structs

RefGraph

An inverse-reference index: for each entity, the entities that reference it.