Hopefully I’m following the conversation correctly so far, but is the point of the diagram check to avoid the case where a 3rd party requires the channel parties to pay more? If so, how do you handle the case where the pure burn is not enough to make it into the mempool so fees have to be added? In this case, I think a 3rd party could make a spend of the ephemeral anchor + attach some fees where the pure burn diagram check succeeds but the package sits in the mempool. Since presumably the parties to the channel want the package confirmed at the going block feerate, they’ll need to RBF the ephemeral anchor spend and end up paying more than if the 3rd party didn’t exist.