Skip unchanged live-sync streams

crates/geth-control/src/lib.rs

@@ -571,6 +571,10 @@ pub enum PeerControlRequest {
         capability: String,
         nonce: String,
     },
+    SyncStatus {
+        peer_card: PeerCard,
+        nonce: String,
+    },
     CasFetch {
         peer_card: PeerCard,
         hash: BlobHash,
@@ -643,6 +647,15 @@ pub enum PeerControlResponse {
         nonce: String,
         note: String,
     },
+    SyncStatus {
+        node_id: String,
+        agent_id: String,
+        endpoint_id: String,
+        remote_endpoint_id: String,
+        watermarks: Vec<SyncWatermark>,
+        nonce: String,
+        note: String,
+    },
     CasFetched {
         node_id: String,
         agent_id: String,
@@ -755,6 +768,12 @@ pub enum PeerControlResponse {
     },
 }
 
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct SyncWatermark {
+    pub stream: String,
+    pub high_water: i64,
+}
+
 #[derive(Debug, thiserror::Error)]
 pub enum ControlError {
     #[error("json error: {0}")]
@@ -1118,6 +1137,24 @@ mod tests {
             response
         );
 
+        let response = PeerControlResponse::SyncStatus {
+            node_id: "node:peer".to_owned(),
+            agent_id: "agent:peer".to_owned(),
+            endpoint_id: "endpoint:peer".to_owned(),
+            remote_endpoint_id: "endpoint:caller".to_owned(),
+            watermarks: vec![SyncWatermark {
+                stream: "kv:prefs".to_owned(),
+                high_water: 42,
+            }],
+            nonce: "nonce".to_owned(),
+            note: "status".to_owned(),
+        };
+        assert_eq!(
+            decode_peer_response(&encode_peer_response(&response).expect("encode"))
+                .expect("decode"),
+            response
+        );
+
         let response = PeerControlResponse::CasFetched {
             node_id: "node:peer".to_owned(),
             agent_id: "agent:peer".to_owned(),
@@ -1161,6 +1198,26 @@ mod tests {
             request
         );
 
+        let request = PeerControlRequest::SyncStatus {
+            peer_card: PeerCard {
+                node_id: "node:caller".into(),
+                agent_id: "agent:caller".into(),
+                endpoints: Vec::new(),
+                issued_at: geth_types::UnixMillis(1),
+                signature: geth_discovery::SignatureMetadata {
+                    namespace: "geth.peer-card.v1@geth.local".to_owned(),
+                    signer: "agent:caller".to_owned(),
+                    public_key: "key".to_owned(),
+                    signature: "sig".to_owned(),
+                },
+            },
+            nonce: "nonce".to_owned(),
+        };
+        assert_eq!(
+            decode_peer_request(&encode_peer_request(&request).expect("encode")).expect("decode"),
+            request
+        );
+
         let response = PeerControlResponse::SshCertSynced {
             node_id: "node:peer".to_owned(),
             agent_id: "agent:peer".to_owned(),