How does the negotiation message thread work, including counter-proposals?

Alongside the versioned offers, a quote request has a message thread (QuoteMessages) where customer and staff communicate. A message can carry an optional proposed price as a counter-proposal — a way to float a number in conversation. Importantly, a proposal in a message is just that: it doesn't itself change the official quote; a new price only becomes binding when staff issue a new…

Alongside the versioned offers, a quote request has a message thread (QuoteMessages) where customer and staff communicate. A message can carry an optional proposed price as a counter-proposal — a way to float a number in conversation. Importantly, a proposal in a message is just that: it doesn't itself change the official quote; a new price only becomes binding when staff issue a new QuoteVersion. This separates informal negotiation (the thread) from formal offers (the versions), so both sides can haggle freely while the "official" price remains explicit and versioned.