Add proposer preferences SSE event (#9308)

This is needed to connect to buildoor (Kurtosis package, acts as a trustless builder)


  


Co-Authored-By: Eitan Seri- Levi <eserilev@gmail.com>

Co-Authored-By: Eitan Seri-Levi <eserilev@ucsc.edu>

Co-Authored-By: Michael Sproul <michaelsproul@users.noreply.github.com>

consensus/types/src/builder/proposer_preferences.rs

@@ -14,8 +14,10 @@ use tree_hash_derive::TreeHash;
 pub struct ProposerPreferences {
     pub dependent_root: Hash256,
     pub proposal_slot: Slot,
+    #[serde(with = "serde_utils::quoted_u64")]
     pub validator_index: u64,
     pub fee_recipient: Address,
+    #[serde(with = "serde_utils::quoted_u64")]
     pub target_gas_limit: u64,
 }
 
@@ -45,4 +47,24 @@ mod tests {
     use super::*;
 
     ssz_and_tree_hash_tests!(ProposerPreferences);
+
+    /// `validator_index` and `target_gas_limit` must serialize as quoted JSON strings (Beacon API
+    /// convention) and round-trip back to their numeric values.
+    #[test]
+    fn quoted_u64_json_serde() {
+        let preferences = ProposerPreferences {
+            dependent_root: Hash256::ZERO,
+            proposal_slot: Slot::new(7),
+            validator_index: 42,
+            fee_recipient: Address::ZERO,
+            target_gas_limit: 30_000_000,
+        };
+
+        let value = serde_json::to_value(&preferences).unwrap();
+        assert_eq!(value["validator_index"], serde_json::json!("42"));
+        assert_eq!(value["target_gas_limit"], serde_json::json!("30000000"));
+
+        let decoded: ProposerPreferences = serde_json::from_value(value).unwrap();
+        assert_eq!(decoded, preferences);
+    }
 }