feat(rpc): add signet_networkStatus endpoint (ENG-479)

Adds a new signet_networkStatus RPC endpoint that returns Signet-specific
network information:
- chain_id: The Signet rollup chain ID
- genesis: The genesis block hash (block 0)
- head: The current head block hash
- headNumber: The current head block number

This addresses the TODOs from the original SignetNoopNetwork implementation
which returned Default::default() for these values. The new endpoint exposes
the actual Signet network state rather than delegating to the host network.

The endpoint is exposed as signet_networkStatus and returns a JSON object
with camelCase field names.

Closes ENG-479

Author: init4samwise

crates/rpc/src/lib.rs

@@ -63,7 +63,7 @@ mod eth;
 pub use eth::{CallErrorData, EthError, eth};
 
 mod signet;
-pub use signet::{error::SignetError, signet};
+pub use signet::{SignetNetworkStatus, error::SignetError, signet};
 
 mod inspect;
 pub use inspect::inspect;

crates/rpc/src/signet/endpoints.rs

@@ -4,13 +4,71 @@ use crate::{
     utils::{await_handler, response_tri},
 };
 use ajj::{HandlerCtx, ResponsePayload};
+use alloy::{eips::BlockId, primitives::B256};
+use reth::providers::{BlockHashReader, BlockNumReader};
 use reth_node_api::FullNodeComponents;
+use serde::Serialize;
 use signet_bundle::{SignetBundleDriver, SignetCallBundle, SignetCallBundleResponse};
 use signet_node_types::Pnt;
 use signet_types::SignedOrder;
 use std::time::Duration;
 use tokio::select;
 
+/// Signet network status information.
+///
+/// This provides Signet-specific network status, as opposed to the host
+/// network status which would be returned by `eth_protocolVersion`.
+#[derive(Debug, Clone, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct SignetNetworkStatus {
+    /// The Signet chain ID.
+    pub chain_id: u64,
+    /// The genesis block hash.
+    pub genesis: B256,
+    /// The current head block hash.
+    pub head: B256,
+    /// The current head block number.
+    pub head_number: u64,
+}
+
+/// Returns the Signet network status including genesis and head block info.
+///
+/// This endpoint provides Signet-specific network information that reflects
+/// the rollup's state rather than the underlying host network.
+pub(super) async fn network_status<Host, Signet>(
+    hctx: HandlerCtx,
+    ctx: RpcCtx<Host, Signet>,
+) -> Result<SignetNetworkStatus, String>
+where
+    Host: FullNodeComponents,
+    Signet: Pnt,
+{
+    let task = async move {
+        let provider = ctx.signet().provider();
+
+        // Get the genesis block hash (block 0)
+        let genesis = provider
+            .block_hash(0)
+            .map_err(|e| e.to_string())?
+            .ok_or_else(|| "genesis block hash not found".to_string())?;
+
+        // Get the current head block number and hash
+        let head_number = provider.last_block_number().map_err(|e| e.to_string())?;
+
+        let head = provider
+            .block_hash(head_number)
+            .map_err(|e| e.to_string())?
+            .ok_or_else(|| "head block hash not found".to_string())?;
+
+        // Get the chain ID from constants
+        let chain_id = ctx.signet().constants().ru_chain_id();
+
+        Ok(SignetNetworkStatus { chain_id, genesis, head, head_number })
+    };
+
+    await_handler!(@option hctx.spawn_blocking(task))
+}
+
 pub(super) async fn send_order<Host, Signet>(
     hctx: HandlerCtx,
     order: SignedOrder,

crates/rpc/src/signet/mod.rs

@@ -5,6 +5,8 @@ use endpoints::*;
 
 pub(crate) mod error;
 
+pub use endpoints::SignetNetworkStatus;
+
 use crate::ctx::RpcCtx;
 use reth_node_api::FullNodeComponents;
 use signet_node_types::Pnt;
@@ -15,5 +17,8 @@ where
     Host: FullNodeComponents,
     Signet: Pnt,
 {
-    ajj::Router::new().route("sendOrder", send_order).route("callBundle", call_bundle)
+    ajj::Router::new()
+        .route("sendOrder", send_order)
+        .route("callBundle", call_bundle)
+        .route("networkStatus", network_status)
 }