Advertise finalized head as LIB on engine-API path

[sduchesneau]

Bug

LIB (last irreversible / finalized block) was never advanced for the Firehose-instrumented op-reth running the live engine-API flow.

The cloned OpFirehoseEngineValidator (op-reth's own engine-validator clone, in crates/firehose/src/engine_validator.rs) started the block tracer with finalized = None:

let tracer = FirehoseBlockTracer::start::<N>(&sealed, None);

so every emitted block carried no finalized reference and downstream LIB never moved.

Fix

Read the finalized head from the node provider and pass it as the block's FinalizedBlockRef:

let finalized = self.provider.finalized_block_num_hash().ok().flatten().map(|num_hash| {
    firehose_tracer::types::FinalizedBlockRef { number: num_hash.number, hash: Some(num_hash.hash) }
});
let tracer = FirehoseBlockTracer::start::<N>(&sealed, finalized);

This mirrors the reth fork's runner.rs (ExEx path), which already does to_finalized_ref(ctx.provider().finalized_block_num_hash()). The op-reth engine-API clone was the one place still passing None. Requires a BlockIdReader bound on the provider; the concrete Node::Provider (BlockchainProvider, with the live forkchoice-tracked finalized) satisfies it.

Validation

• cargo check -p reth-optimism-firehose / -p reth-optimism-node ✅
• cargo build -p op-reth --bin op-reth ✅

🤖 Generated with Claude Code

[UlysseCorbeil]

lgtm

[sduchesneau]

DO NOT MERGE YET: it does not fix the LIB. I should make PR-builds faster though