Interface MutationStoreShape

Secondary index of property atoms the parser deferred out of byId on huge files (deferPropertyAtomIndex). These still occupy express ids in the source, so the overlay id allocator must clear them too — otherwise a deferred atom sitting above max(byId) gets its id reused for a new overlay entity, producing a duplicate #ID= definition once the exporter emits both. See @ifc-lite/export getCompleteEntityIndex.

The columnar entity table. IFCX-origin and reconstructed collab-room stores leave entityIndex.byId empty and carry their membership only here, so the overlay id allocator must clear these ids too — otherwise the first overlay entity is handed express id 1, which the base store already owns (#5008).

IFC schema identifier of the loaded model, when the source provides it.