Yes, I think that would be my favorite too. So this gives
request-pay
offer-pay
accept-pay
for invoice flow, and
request-bill
offer-bill
accept-bill
for “regular” flow (he quotes reflect my hope that invoice flow will actually become the one in regular use:-)
We could allow pay-bill as a synonym for accept-bill.
Btw, although it requires more typing,
request-payment
offer-payment
accept-payment
sound slightly better to me.