dpad85
commented
1 year ago We used to have that option in the android app but removed it because it was not well implemented and could end up being costly for the user.
In any case the idea is quite simple : set the (trampoline) fee beforehand, so that the wallet knows how much is left and can be spent without leaving any dust.
Now what fee should be used - that's the question. It must be reasonably high because we cannot retry the payment with higher fee. I think the best option is to pick a reasonable value from the trampoline fees settings, but let the user see (and edit) the value of the fee before actually sending the payment.
When sending to a lightning address or a LNURL-pay invoice, it would be great to have the ability to ‘send max’ where the full balance minus some reserve for the fee is able to be sent. Currently, Phoenix doesn’t even show your balance on the screen when you are entering in the amount of sats to send. If the user does go back a screen to see their balance, re-pastes in the lightning address, enters their full balance, then hits send, the transaction fails due to insufficient funds. This is understandable to someone familiar with lightning, but not a new user who doesn’t understand why they don’t have enough funds. This would be solved with a “send max” button that shows the user the most they can send.