Use min_seed_lookahead in ChainSpec::proposer_shuffling_decision_slot

michaelsproul · michaelsproul · commit 353fdcbf6a76 · 2025-09-25T11:56:20.000+10:00
diff --git a/consensus/types/src/chain_spec.rs b/consensus/types/src/chain_spec.rs
@@ -871,16 +871,19 @@ impl ChainSpec {
     pub fn proposer_shuffling_decision_slot<E: EthSpec>(&self, epoch: Epoch) -> Slot {
         if self.fork_name_at_epoch(epoch).fulu_enabled() {
             // Post-Fulu the proposer shuffling decision slot for epoch N is the slot at the end
-            // of epoch N - 2.
-            // FIXME(sproul): rewrite this in terms of min_seed_lookahead?
+            // of epoch N - 2 (note: min_seed_lookahead=1 in all current configs).
             epoch
-                .saturating_sub(Epoch::new(1))
+                .saturating_sub(self.min_seed_lookahead)
                 .start_slot(E::slots_per_epoch())
                 .saturating_sub(1_u64)
         } else {
-            // Pre-Fulu the proposer shuffling decision slot for epcoch N is the slot at the end of
-            // epoch N - 1.
-            epoch.start_slot(E::slots_per_epoch()).saturating_sub(1_u64)
+            // Pre-Fulu the proposer shuffling decision slot for epoch N is the slot at the end of
+            // epoch N - 1 (note: +1 -1 for min_seed_lookahead=1 in all current configs).
+            epoch
+                .saturating_add(Epoch::new(1))
+                .saturating_sub(self.min_seed_lookahead)
+                .start_slot(E::slots_per_epoch())
+                .saturating_sub(1_u64)
         }
     }
 
