I think they misunderstand the purpose of the version signal across the protocol: if signals if a boundary point for api action can't do (only) what it used to do, it signals what might happen next.<p>If v1.0 is deployed, does it subsume v0.9 (augment) or does it invalidate? At least two different outcomes. Now, analyse by actor: what could an initiator do, what could a responder do? Probably two or three choices. It's heading to a potential combinatorial explosion of pairs of behaviour across the sender/respondent barrier, both independent actors.. So, define each side, and limit this space but keep the version signalling to drive the decision logic.<p>I think the original author gets this but proposes a rigid outcome. Well, sorry, but there are choices.<p>Look at how zfs signals extensions and their effect on mutable state in the FS. Or, NFS