A brand licensing a face needs two things a handshake does not give them: proof of consent that survives a change of staff, and certainty that they are not commissioning something that breaches an exclusivity clause somebody signed two years ago.
Excluded brands are a field on the boundary set. A request naming a competitor the creator is contractually barred from appearing with is refused server-side, before anything is produced — the contract becomes a rule the system enforces rather than a document somebody is supposed to have read.
The provenance manifest is the artifact to hand a card network, a broadcaster's compliance desk or opposing counsel. It is signed, so its authenticity does not rest on our word.