delete

DELETE_ORPHAN (not DELETE_ALL) so shared :Source nodes survive unless this was their last reference.

The last provenance path still going through the object view. It handles parallel revisions: deleting a proposition that cites one source at two revisions takes both edges and leaves that source standing while anything else cites it. deleting a proposition takes its parallel revision edges and only its own orphaned source pins that against a real Neo4j, which is why the raw-Cypher rewrite the write and read paths needed is not needed here.