+ // The protocol has two different commitment number concepts - the "commitment
+ // transaction number", which starts from 0 and counts up, and the "revocation key
+ // index" which starts at INITIAL_COMMITMENT_NUMBER and counts down. We track
+ // commitment transaction numbers by the index which will be used to reveal the
+ // revocation key for that commitment transaction, which means we have to convert them
+ // to protocol-level commitment numbers here...
+
+ // next_local_commitment_number is the next commitment_signed number we expect to
+ // receive (indicating if they need to resend one that we missed).