From b266cc2482fa3c04178ecf2321866087eb0a7697 Mon Sep 17 00:00:00 2001
From: jsvisa <delweng@gmail.com>
Date: Tue, 28 Oct 2025 08:30:05 +0000
Subject: [PATCH] eth/syncer: advance safe and finalized block

Signed-off-by: jsvisa <delweng@gmail.com>
---
 eth/syncer/syncer.go | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/eth/syncer/syncer.go b/eth/syncer/syncer.go
index 6b33ec54ba..02dc224d06 100644
--- a/eth/syncer/syncer.go
+++ b/eth/syncer/syncer.go
@@ -22,6 +22,7 @@ import (
 	"sync"
 	"time"
 
+	beaconparams "github.com/ethereum/go-ethereum/beacon/params"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/eth"
@@ -129,7 +130,11 @@ func (s *Syncer) run() {
 				break
 			}
 			if resync {
-				req.errc <- s.backend.Downloader().BeaconDevSync(ethconfig.FullSync, target)
+				err := s.backend.Downloader().BeaconDevSync(ethconfig.FullSync, target)
+				if err == nil {
+					s.advanceDevFinality()
+				}
+				req.errc <- err
 			}
 
 		case <-ticker.C:
@@ -196,3 +201,33 @@ func NewAPI(s *Syncer) *API {
 func (api *API) Sync(target common.Hash) error {
 	return api.s.Sync(target)
 }
+
+// advanceDevFinality synthesizes safe/finalized heads for the dev beacon-sync
+func (s *Syncer) advanceDevFinality() {
+	bc := s.backend.BlockChain()
+
+	head := bc.CurrentBlock()
+	if head == nil {
+		return
+	}
+
+	safeNumber := head.Number.Uint64() - beaconparams.EpochLength
+	safeHeader := bc.GetHeaderByNumber(safeNumber)
+	if safeHeader == nil {
+		log.Warn("Dev sync could not resolve safe header", "number", safeNumber)
+		return
+	}
+	if safe := bc.CurrentSafeBlock(); safe == nil || safe.Hash() != safeHeader.Hash() {
+		bc.SetSafe(safeHeader)
+	}
+
+	finalNumber := safeNumber - beaconparams.EpochLength
+	finalHeader := bc.GetHeaderByNumber(finalNumber)
+	if finalHeader == nil {
+		log.Warn("Dev sync could not resolve finalized header", "number", finalNumber)
+		return
+	}
+	if finalized := bc.CurrentFinalBlock(); finalized == nil || finalized.Hash() != finalHeader.Hash() {
+		bc.SetFinalized(finalHeader)
+	}
+}