DvP Settlement Engine in Daml

Why does the lesson's design need no escrow agent to make the two legs settle together?

• The auditor holds both assets until the trade completes
• Both legs are actions in one Daml transaction, which commits all or nothing
• The registrar approves each leg separately

In the lesson's design, what does `ProposeDvp` do to the buyer's `Cash` contract?

• Nothing; the cash stays active until the seller accepts
• Archives it and stores its data in the new `DvpProposal`, so it cannot be spent elsewhere
• Transfers it straight to the seller