related_party_consent_missing
A subscription_terms row carrying related_party = true was written, signed or activated with no recorded reference to an executed Conflict Disclosure and Consent Letter. This is the related-party half of the no-custom-price-without-paper rule, and it fails closed for the same reason pricing_memo_ref is required: the deal most likely to be asked about is the one where the owner is a salaried employee of the counterparty. What an operator does: execute the letter with an authorized officer of the counterparty, record it with tenant.related_party_consent.record, and retry. There is no override - a related-party order without the consent letter is exactly the state the constraint exists to make unrepresentable. P1, unbuilt, and the column it reads is not yet specified by adr/0028/adr/0029 (see 20-commercial-operations.md §7).
Problem shape
Every non-2xx response is an RFC 9457 application/problem+json body. The type URI below is stable and machine-matchable, so branch on the final path segment (the code) and treat the status as redundant confirmation. See the error-handling guide.
{
"type": "https://docs.vocapable.com/errors/related_party_consent_missing",
"title": "…",
"status": 409,
"detail": "…",
"instance": "/v1/…"
}