feat(op-rpc): finalize signal_superchain_v1 's endpoint (paradigmxyz#15338)

Co-authored-by: Matthias Seitz <matthias.seitz@outlook.de>

Author: lean-apple

crates/optimism/rpc/src/engine.rs

@@ -1,7 +1,7 @@
 //! Implements the Optimism engine API RPC methods.
 
 use alloy_eips::eip7685::Requests;
-use alloy_primitives::{BlockHash, B256, U64};
+use alloy_primitives::{BlockHash, B256, B64, U64};
 use alloy_rpc_types_engine::{
     ClientVersionV1, ExecutionPayloadBodiesV1, ExecutionPayloadInputV2, ExecutionPayloadV3,
     ForkchoiceState, ForkchoiceUpdated, PayloadId, PayloadStatus,
@@ -10,16 +10,16 @@ use derive_more::Constructor;
 use jsonrpsee::proc_macros::rpc;
 use jsonrpsee_core::{server::RpcModule, RpcResult};
 use op_alloy_rpc_types_engine::{
-    OpExecutionData, OpExecutionPayloadV4, ProtocolVersion, SuperchainSignal,
+    OpExecutionData, OpExecutionPayloadV4, ProtocolVersion, ProtocolVersionFormatV0,
+    SuperchainSignal,
 };
 use reth_chainspec::EthereumHardforks;
 use reth_node_api::{EngineTypes, EngineValidator};
 use reth_rpc_api::IntoEngineApiRpcModule;
 use reth_rpc_engine_api::EngineApi;
-use reth_rpc_server_types::result::internal_rpc_err;
 use reth_storage_api::{BlockReader, HeaderProvider, StateProviderFactory};
 use reth_transaction_pool::TransactionPool;
-use tracing::trace;
+use tracing::{info, trace};
 
 /// The list of all supported Engine capabilities available over the engine endpoint.
 ///
@@ -40,6 +40,16 @@ pub const OP_ENGINE_CAPABILITIES: &[&str] = &[
     "engine_signalSuperchainV1",
 ];
 
+/// OP Stack protocol version
+/// See also: <https://github.com/ethereum-optimism/op-geth/blob/c3a989eb882d150a936df27bcfa791838b474d55/params/superchain.go#L13-L13>
+pub const OP_STACK_SUPPORT: ProtocolVersion = ProtocolVersion::V0(ProtocolVersionFormatV0 {
+    build: B64::ZERO,
+    major: 9,
+    minor: 0,
+    patch: 0,
+    pre_release: 0,
+});
+
 /// Extension trait that gives access to Optimism engine API RPC methods.
 ///
 /// Note:
@@ -335,9 +345,16 @@ where
         Ok(self.inner.get_payload_bodies_by_range_v1_metered(start.to(), count.to()).await?)
     }
 
-    async fn signal_superchain_v1(&self, _signal: SuperchainSignal) -> RpcResult<ProtocolVersion> {
+    async fn signal_superchain_v1(&self, signal: SuperchainSignal) -> RpcResult<ProtocolVersion> {
         trace!(target: "rpc::engine", "Serving signal_superchain_v1");
-        Err(internal_rpc_err("unimplemented"))
+        info!(
+            target: "rpc::engine",
+            "Received superchain version signal local={:?} required={:?} recommended={:?}",
+            OP_STACK_SUPPORT,
+            signal.required,
+            signal.recommended
+        );
+        Ok(OP_STACK_SUPPORT)
     }
 
     async fn get_client_version_v1(