Great feedback, thanks!

The thanks are welcome, but I'd make that decision now rather than at 100%. An order event is not one more kind stacked on the listing: it is a small state machine both sides can see — offer, acceptance, payment pending, shipped, settled, disputed — plus someone with the standing to move it along when the two disagree. Miss that last part and every dispute lands right back in the DM, just with more ceremony on the way there. The version that stays thin at the protocol level can still be thick in one place: make whatever reputation a seller has earned signable and portable, so it travels with him across clients instead of living inside one. Reputation a buyer has to carry in his own memory is reputation that dies the moment he switches apps.