This database stores CMD_FULFILL_HTLC and CMD_FAIL_HTLC that we have received from downstream
(either directly via UpdateFulfillHtlc or by extracting the value from the
blockchain).
This means that this database is only used in the context of *relaying* payments.
We need to be sure that if downstream is able to pull funds from us, we can always
do the same from upstream, otherwise we lose money. Hence the need for persistence
to handle all corner cases.
This database stores CMD_FULFILL_HTLC and CMD_FAIL_HTLC that we have received from downstream (either directly via UpdateFulfillHtlc or by extracting the value from the blockchain).
This means that this database is only used in the context of *relaying* payments.
We need to be sure that if downstream is able to pull funds from us, we can always do the same from upstream, otherwise we lose money. Hence the need for persistence to handle all corner cases.