Module spatial_canonical_parent 

Cycle-safe canonical-parent resolution, split out of spatial.rs (same reason spatial_elevation.rs, spatial_invariant.rs and spatial_tree.rs already are: stay under the module-size ratchet). Mirrors packages/parser/src/spatial-hierarchy-canonical-parent.ts, which split the same concern out of spatial-hierarchy-builder.ts for the same reason.

Constants

CYCLE_CHECK_VISIT_BUDGET 🔒

Upper bound on aggregate-graph node visits spent on back-edge cycle checks for one upload. The check only runs for children named by MORE THAN ONE IFCRELAGGREGATES (already malformed) and costs one descendant walk per such child - O(V+E) each - so a crafted upload with thousands of contested children could otherwise hold a blocking worker for O(C·(V+E)). Past the budget the resolver falls back to plain first-declared-wins and logs once. Mirrors CYCLE_CHECK_VISIT_BUDGET in packages/parser/src/spatial-hierarchy-canonical-parent.ts.

Functions

aggregated_descendants 🔒

Aggregated descendants of child_id (transitive, forward IFCRELAGGREGATES), charged against budget. None when the budget ran out mid-walk: a partial set must not be used, since a missing descendant reads as “no cycle” - the wrong side to err on. Used only to disqualify a tied candidate parent that would close a cycle back through the child itself (#4246: the STEP-authoring-tool mistake of declaring an aggregation pair in both directions, or an indirect A -> B -> C -> A chain) - the common case (one candidate) never calls this. Mirrors packages/parser/src/spatial-hierarchy-canonical-parent.ts’s aggregatedDescendants.

resolve_aggregate_canonical_parents 🔒

Resolve each spatial child’s ONE canonical IFCRELAGGREGATES parent, globally, from the raw relationship list. Plain first-declared-wins, EXCEPT that a candidate closing a cycle back through the child is skipped first (#4246) - a mutual or longer aggregation back-edge (a STEP-authoring-tool mistake: a parent/child pair declared in both directions) cannot win a tie against a candidate that doesn’t orphan the child’s own subtree from itself. Falls through to plain first-declared if every candidate closes a cycle, so a child is never left without a parent. Mirrors packages/parser/src/spatial-hierarchy-canonical-parent.ts’s computeCanonicalParent.

resolve_aggregate_canonical_parents_with_budget 🔒