Pay
When we don't have enough incoming liquidity to receive a payment, our peer may open a channel to us on-the-fly to carry that payment. This message contains details that allow us to recalculate the fee that our peer will take in exchange for the new channel. This allows us to combine multiple requests for the same payment and figure out the final fee that will be applied.
Parameters
chain we're on.
total capacity of the channel our peer will open to us (some of the funds may be on their side).
payment amount covered by this new channel: we will receive push_msat = amountMsat - fees.
minimum amount for a pay-to-open to be attempted, this should be compared to the total amount in the case of an MPP payment.
fees that will be deducted from the amount pushed to us (this fee covers the on-chain fees our peer will pay to open the channel).
payment hash.
after the proposal expires, our peer will fail the payment and won't open a channel to us.
onion packet that we would have received if there had been a channel to forward the payment to.