persist
The first half of persistReturningCanonical: entities and propositions are saved, and nothing else happens. Saved means committed only when no transaction wraps the call; inside an ambient transaction the claims land with the caller's commit, not here.
Split out so a caller can act on saved claims before anything fallible runs. Structural wiring goes through mergeRelationship, which can throw, and while it lived inside the same call the propositions were already stored by the time it failed — but a caller could not do anything about that until the call returned, which it never did. Extraction-run lineage is the caller that has to: attribution is a statement about claims that exist, and a failing edge write must not be able to strand a stored claim with no record of the run that produced it.
A caller that has no such ordering requirement should use persistReturningCanonical, which is this followed by wireStructuralRelationships and is what it always was.
Return
The stored proposition for each one persisted, and the input-id to stored-id mapping.
Parameters
Where propositions go.
Where entities go.