Inbound capacity does not account for remote's commitment fee

[gcomte]

When receiving a payment through (a) channel(s) that was opened by the remote node, it is rightfully being checked that the sender doesn't send so much funds that the channel closing fee wouldn't be covered anymore (2 * remote_commit_tx_fee).

The remote party's commitment fee does however not seem to be considered when calculating a channels inbound capacity.

This is misleading and may lead a user to create invoices with bigger amounts than the user can actually receive.

[TheBlueMatt]

Maybe more generally put, we should expose a concrete idea of what we think we can realistically receive over a channel in inbound_capacity, rather than the total we can receive excluding all limits. Sadly in lightning there's various things the remote side will do that we can't know exactly so there's no way to communicate exactly what we can currently receive, but we can do better than we do today.