Optionalchallengeid of the challenge the last credential was minted against, so the caller can correlate it with the seller's side.
How many credentials were minted and sent before the failure (0, 1 or 2).
OptionalcreditsTotal credits named by the challenges those credentials were minted
against, as a decimal string. Present whenever credentialsPresented > 0.
What a buyer-side failure reports about money already committed.
payments.mpp.fetchreturns this accounting on its success path (credentialsPresented/creditsPresentedonMppFetchResult). It is repeated on the ERROR path because that is where a caller needs it most: the credential and its access token are function-local and gone once the helper throws, so an error without these numbers leaves the caller unable to tell whether money left — the one outcome a buyer helper must never produce.Read it with mppSpendOf rather than casting: it rides on
PaymentsErrortoo (amaxCreditsorplanIdguard can fire on the re-challenge turn, after a credential has already been presented).