Use typed lookup stage formatting

src/retrieval/failure.rs

@@ -1,4 +1,5 @@
 // SPDX-FileCopyrightText: 2025 Semiotic AI, Inc.
+// SPDX-FileCopyrightText: 2026 Joseph Livesey <jlivesey@gmail.com>
 //
 // SPDX-License-Identifier: Apache-2.0
 
@@ -91,7 +92,7 @@ pub(crate) fn lookup_request_failed(
     error: TransportError,
 ) -> RetrievalError {
     RetrievalError::Rpc(crate::errors::RpcError::request_failed(
-        format!("{operation}({tx_hash})", operation = stage.operation_name()),
+        format!("{stage}({tx_hash})"),
         error,
     ))
 }

src/retrieval/types.rs

@@ -1,9 +1,12 @@
 // SPDX-FileCopyrightText: 2025 Semiotic AI, Inc.
+// SPDX-FileCopyrightText: 2026 Joseph Livesey <jlivesey@gmail.com>
 //
 // SPDX-License-Identifier: Apache-2.0
 
 //! Data types for combined gas and amount retrieval
 
+use std::fmt;
+
 use alloy_chains::NamedChain;
 use alloy_primitives::{Address, BlockNumber, TxHash, U256};
 use serde::{Deserialize, Serialize};
@@ -48,6 +51,7 @@ pub enum CombinedDataLookupStage {
 }
 
 impl CombinedDataLookupStage {
+    /// Stable RPC operation label used in logs and operator-facing errors.
     #[must_use]
     pub const fn operation_name(self) -> &'static str {
         match self {
@@ -57,6 +61,12 @@ impl CombinedDataLookupStage {
     }
 }
 
+impl fmt::Display for CombinedDataLookupStage {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        formatter.write_str((*self).operation_name())
+    }
+}
+
 /// Which pass produced a lookup error while enriching a decoded transfer log.
 #[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
 pub enum CombinedDataLookupPass {
@@ -249,6 +259,18 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_combined_lookup_stage_display_matches_rpc_operation_name() {
+        assert_eq!(
+            CombinedDataLookupStage::Transaction.to_string(),
+            "get_transaction_by_hash"
+        );
+        assert_eq!(
+            CombinedDataLookupStage::Receipt.to_string(),
+            "get_transaction_receipt"
+        );
+    }
+
     #[test]
     fn test_total_gas_cost_basic() {
         // Test basic calculation with L2 gas only