op-node/rollup: Showcase feature/fork separation pattern with seq dri…

…ft change

op-node/rollup/chain_spec.go

@@ -62,11 +62,17 @@ func (s *ChainSpec) MaxRLPBytesPerChannel(t uint64) uint64 {
 	return maxRLPBytesPerChannelBedrock
 }
 
+// IsFeatMaxSequencerDriftConstant specifies in which fork the max sequencer drift change to a
+// constant will be performed.
+func (s *ChainSpec) IsFeatMaxSequencerDriftConstant(t uint64) bool {
+	return s.config.IsFjord(t)
+}
+
 // MaxSequencerDrift returns the maximum sequencer drift for the given block timestamp. Until Fjord,
 // this was a rollup configuration parameter. Since Fjord, it is a constant, so its effective value
 // should always be queried via the ChainSpec.
 func (s *ChainSpec) MaxSequencerDrift(t uint64) uint64 {
-	if s.config.IsFjord(t) {
+	if s.IsFeatMaxSequencerDriftConstant(t) {
 		return maxSequencerDriftFjord
 	}
 	return s.config.MaxSequencerDrift