server: remove accountability signal experiment period

In the previous iteration with endorsement
signaling, the recommendation was for the sender to
set it to 1 and that could have had privacy concerns
when first deploying given that the default was to
downgrade the signal to 0. In the latest proposal
the recommended default for both sending and
forwarding nodes is to set `accountable` to 0.
As a result, the dates have been removed given
that there are no privacy risks associated
with relaying the signal with zero values.

Author: elnosh

docs/release-notes/release-notes-0.21.0.md

@@ -48,6 +48,10 @@
   This applies to both funders and fundees, with the ability to override the
   value during channel opening or acceptance.
 
+* Rename [experimental endorsement signal](https://github.com/lightning/blips/blob/a833e7b49f224e1240b5d669e78fa950160f5a06/blip-0004.md)
+  to [accountable](https://github.com/lightningnetwork/lnd/pull/10367) to match
+  the latest [proposal](https://github.com/lightning/blips/pull/67).
+
 ## RPC Updates
 
 ## lncli Updates

htlcswitch/link.go

@@ -3346,8 +3346,6 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg) {
 func (l *channelLink) experimentalAccountability(
 	customUpdateAdd record.CustomSet) fn.Option[byte] {
 
-	// Only relay experimental signal if we are within the experiment
-	// period.
 	if !l.cfg.ShouldFwdExpAccountability() {
 		return fn.None[byte]()
 	}

rpcserver.go

@@ -775,13 +775,7 @@ func (r *rpcServer) addDeps(ctx context.Context, s *server,
 			return nil
 		},
 		ShouldSetExpAccountability: func() bool {
-			if s.cfg.ProtocolOptions.NoExpAccountability() {
-				return false
-			}
-
-			return clock.NewDefaultClock().Now().Before(
-				AccountabilityExperimentEnd,
-			)
+			return !s.cfg.ProtocolOptions.NoExpAccountability()
 		},
 	}
 

server.go

@@ -139,12 +139,6 @@ var (
 	// TODO(roasbeef): add command line param to modify.
 	MaxFundingAmount = funding.MaxBtcFundingAmount
 
-	// AccountabilityExperimentEnd is the time after which nodes should stop
-	// propagating experimental accountable signals.
-	//
-	// Per blip04: January 1, 2026 12:00:00 AM UTC in unix seconds.
-	AccountabilityExperimentEnd = time.Unix(1767225600, 0)
-
 	// ErrGossiperBan is one of the errors that can be returned when we
 	// attempt to finalize a connection to a remote peer.
 	ErrGossiperBan = errors.New("gossiper has banned remote's key")
@@ -4432,13 +4426,7 @@ func (s *server) peerConnected(conn net.Conn, connReq *connmgr.ConnReq,
 		AuxTrafficShaper:       s.implCfg.TrafficShaper,
 		AuxChannelNegotiator:   s.implCfg.AuxChannelNegotiator,
 		ShouldFwdExpAccountability: func() bool {
-			if s.cfg.ProtocolOptions.NoExpAccountability() {
-				return false
-			}
-
-			return clock.NewDefaultClock().Now().Before(
-				AccountabilityExperimentEnd,
-			)
+			return !s.cfg.ProtocolOptions.NoExpAccountability()
 		},
 		NoDisconnectOnPongFailure: s.cfg.NoDisconnectOnPongFailure,
 	}