Abort the negotiation — terminal (CH-5).
Optionalreason: stringAccept the standing proposal — terminal (CH-5).
Counter the standing proposal with new terms.
Open a negotiation with the first proposal.
Feed a verified inbound channel message. No-op for non-RFQ types or messages arriving after a terminal state (a late duplicate of an end message). Throws only on a protocol violation that the channel layer can't catch (e.g. accept referencing an unknown proposal).
Reject the negotiation — terminal (CH-5).
Optionalreason: string
The proposal currently on the table, or null before the first offer.