Reorgs not possible on op-reth

[joshieDo]

Describe the feature

Any block that gets sent from op-node to op-reth is actually built by op-reth. Including reorg blocks. This means that if there would be a 1 block reorg, we would receive a FCU with head to block N-1 with attributes to build the new block N.

If this would be mainnet, since N-1 is an ancestor, we would just skip the payload job according to mainnet execution-api specs:

Client software MAY skip an update of the forkchoice state and MUST NOT begin a payload build process if forkchoiceState.headBlockHash references a VALID ancestor of the head of canonical chain, i.e. the ancestor passed [payload validation](https://github.com/ethereum/execution-apis/blob/main/src/engine/paris.md#payload-validation) process and deemed VALID. In the case of such an event, client software MUST return {payloadStatus: {status: VALID, latestValidHash: forkchoiceState.headBlockHash, validationError: null}, payloadId: null}.

In case of op-reth, we update the head , however we don't rewind the state, leading to the payload job being done against block N state instead of block N - 1 state

reth/crates/consensus/beacon/src/engine/mod.rs

Lines 448 to 464 in 79d505a

	/// Returns `true` if the head needs to be updated.
	fn on_head_already_canonical(
	&self,
	header: &SealedHeader,
	attrs: &mut Option<EngineT::PayloadAttributes>,
	) -> bool {
	// On Optimism, the proposers are allowed to reorg their own chain at will.
	#[cfg(feature = "optimism")]
	if self.blockchain.chain_spec().is_optimism() {
	debug!(
	target: "consensus::engine",
	fcu_head_num=?header.number,
	current_head_num=?self.blockchain.canonical_tip().number,
	"[Optimism] Allowing beacon reorg to old head"
	);
	return true
	}

reth/crates/consensus/beacon/src/engine/mod.rs

Lines 406 to 425 in 79d505a

	if should_update_head {
	let head = outcome.header();
	let _ = self.update_head(head.clone());
	self.listeners.notify(BeaconConsensusEngineEvent::CanonicalChainCommitted(
	Box::new(head.clone()),
	elapsed,
	));
	}
	// Validate that the forkchoice state is consistent.
	let on_updated = if let Some(invalid_fcu_response) =
	self.ensure_consistent_forkchoice_state(state)?
	{
	trace!(target: "consensus::engine", ?state, "Forkchoice state is inconsistent");
	invalid_fcu_response
	} else if let Some(attrs) = attrs {
	// the CL requested to build a new payload on top of this new VALID head
	let head = outcome.into_header().unseal();
	self.process_payload_attributes(attrs, head, state)
	} else {

Additional context

No response

[joshieDo]

closing since it's wrong. we do call state_by_block_hash when building the payload