Re-add next epoch lookahead for PTC duties

apis/validator/duties/ptc.yaml

@@ -8,19 +8,21 @@ post:
     which should be performed by validators, for a particular epoch.
 
     Duties should only need to be checked once per epoch,
-    however a chain reorganization could occur, resulting in a change of duties. For full safety,
+    however a chain reorganization (of > MIN_SEED_LOOKAHEAD epochs) could occur, resulting in a change of duties. For full safety,
     you should monitor head events and confirm the dependent root in this response matches:
 
       - event.previous_duty_dependent_root when `compute_epoch_at_slot(event.slot) == epoch`
 
+      - event.current_duty_dependent_root when `compute_epoch_at_slot(event.slot) + 1 == epoch`
+
       - event.block otherwise
 
 
     The dependent_root value is `get_block_root_at_slot(state, compute_start_slot_at_epoch(epoch - 1) - 1)`
     or the genesis block root in the case of underflow."
   parameters:
     - name: epoch
-      description: "Epoch for which to obtain PTC duties. Must not be greater than the current epoch"
+      description: "Epoch for which to obtain PTC duties. Must not be greater than the next epoch"
       in: path
       required: true
       schema:

validator-flow.md

@@ -55,7 +55,7 @@ If reorg is detected, ask for new attester duties and proceed from 1..
 
 ### PTC Attesting
 
-On start of every epoch beginning with the Gloas fork, validator should [fetch PTC duties](#/Validator/getPtcDuties) for the current epoch.
+On start of every epoch beginning with the Gloas fork, validator should [fetch PTC duties](#/Validator/getPtcDuties) for the current and next epoch.
 Result are array of objects with validator index and assigned slot for payload timeliness committee participation.
 
 PTC Attesting: