From 2f54f03ebf04fd465506aef8136fb218e61d2d4c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C4=B1nar=20Aksoy?= <aksoy.pinar@metu.edu.tr>
Date: Sun, 29 Mar 2026 16:46:16 +0300
Subject: [PATCH] fix: verify consensus rpc chain_id during startup

Call the existing check_rpc() method after sync completes to
verify the consensus RPC's chain_id matches the configured
network. If there's a mismatch, the client stops with an
IncorrectRpcNetwork error instead of silently serving data
from the wrong chain.

Closes #544
---
 ethereum/src/consensus.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/ethereum/src/consensus.rs b/ethereum/src/consensus.rs
index a95046cd..80907afe 100644
--- a/ethereum/src/consensus.rs
+++ b/ethereum/src/consensus.rs
@@ -171,6 +171,12 @@ impl<S: ConsensusSpec, R: ConsensusRpc<S>, DB: Database> ConsensusClient<S, R, D
                 }
             }
 
+            if let Err(err) = inner.check_rpc().await {
+                error!(target: "helios::consensus", err = %err, "chain id mismatch with consensus rpc");
+                _ = sync_status_send.send(ConsensusSyncStatus::Error(err.to_string()));
+                return;
+            }
+
             _ = inner.send_blocks().await;
             _ = sync_status_send.send(ConsensusSyncStatus::Synced);