docs: enhance DebugNode trait documentation (#16872)

Co-authored-by: Dan Cline <6798349+Rjected@users.noreply.github.com>

crates/node/builder/src/launch/debug.rs

@@ -7,18 +7,78 @@ use reth_consensus_debug_client::{DebugConsensusClient, EtherscanBlockProvider,
 use reth_node_api::{BlockTy, FullNodeComponents};
 use std::sync::Arc;
 use tracing::info;
-/// [`Node`] extension with support for debugging utilities, see [`DebugNodeLauncher`] for more
-/// context.
+
+/// [`Node`] extension with support for debugging utilities.
+///
+/// This trait provides additional necessary conversion from RPC block type to the node's
+/// primitive block type, e.g. `alloy_rpc_types_eth::Block` to the node's internal block
+/// representation.
+///
+/// This is used in conjunction with the [`DebugNodeLauncher`] to enable debugging features such as:
+///
+/// - **Etherscan Integration**: Use Etherscan as a consensus client to follow the chain and submit
+///   blocks to the local engine.
+/// - **RPC Consensus Client**: Connect to an external RPC endpoint to fetch blocks and submit them
+///   to the local engine to follow the chain.
+///
+/// See [`DebugNodeLauncher`] for the launcher that enables these features.
+///
+/// # Implementation
+///
+/// To implement this trait, you need to:
+/// 1. Define the RPC block type (typically `alloy_rpc_types_eth::Block`)
+/// 2. Implement the conversion from RPC format to your primitive block type
+///
+/// # Example
+///
+/// ```ignore
+/// impl<N: FullNodeComponents<Types = Self>> DebugNode<N> for MyNode {
+///     type RpcBlock = alloy_rpc_types_eth::Block;
+///
+///     fn rpc_to_primitive_block(rpc_block: Self::RpcBlock) -> BlockTy<Self> {
+///         // Convert from RPC format to primitive format by converting the transactions
+///         rpc_block.into_consensus().convert_transactions()
+///     }
+/// }
+/// ```
 pub trait DebugNode<N: FullNodeComponents>: Node<N> {
     /// RPC block type. Used by [`DebugConsensusClient`] to fetch blocks and submit them to the
-    /// engine.
+    /// engine. This is inteded to match the block format returned by the external RPC endpoint.
     type RpcBlock: Serialize + DeserializeOwned + 'static;
 
     /// Converts an RPC block to a primitive block.
+    ///
+    /// This method handles the conversion between the RPC block format and the internal primitive
+    /// block format used by the node's consensus engine.
+    ///
+    /// # Example
+    ///
+    /// For Ethereum nodes, this typically converts from `alloy_rpc_types_eth::Block`
+    /// to the node's internal block representation.
     fn rpc_to_primitive_block(rpc_block: Self::RpcBlock) -> BlockTy<Self>;
 }
 
 /// Node launcher with support for launching various debugging utilities.
+///
+/// This launcher wraps an existing launcher and adds debugging capabilities when
+/// certain debug flags are enabled. It provides two main debugging features:
+///
+/// ## RPC Consensus Client
+///
+/// When `--debug.rpc-consensus-ws <URL>` is provided, the launcher will:
+/// - Connect to an external RPC `WebSocket` endpoint
+/// - Fetch blocks from that endpoint
+/// - Submit them to the local engine for execution
+/// - Useful for testing engine behavior with real network data
+///
+/// ## Etherscan Consensus Client
+///
+/// When `--debug.etherscan [URL]` is provided, the launcher will:
+/// - Use Etherscan API as a consensus client
+/// - Fetch recent blocks from Etherscan
+/// - Submit them to the local engine
+/// - Requires `ETHERSCAN_API_KEY` environment variable
+/// - Falls back to default Etherscan URL for the chain if URL not provided
 #[derive(Debug, Clone)]
 pub struct DebugNodeLauncher<L = EngineNodeLauncher> {
     inner: L,
@@ -66,7 +126,6 @@ where
             });
         }
 
-        // TODO: migrate to devmode with https://github.com/paradigmxyz/reth/issues/10104
         if let Some(maybe_custom_etherscan_url) = config.debug.etherscan.clone() {
             info!(target: "reth::cli", "Using etherscan as consensus client");