1 files changed, 30 insertions, 1 deletions
diff --git a/src/api/peers.rs b/src/api/peers.rs
index b2658a5..b12e3bf 100644
--- a/src/api/peers.rs
+++ b/src/api/peers.rs
@@ -15,6 +15,7 @@ use utoipa::ToSchema;
 
 use super::store_status;
 use crate::peer::forgotten_path;
+use crate::replica::Epoch;
 use crate::state::{unix_millis, AppState, HelloState, Liveness, PeerMembership, PeerState};
 use crate::store;
 
@@ -27,6 +28,23 @@ pub(crate) enum PeerLivenessStatus {
 
 #[derive(Debug, Serialize, ToSchema)]
 #[serde(rename_all = "camelCase")]
+pub(crate) struct EpochInfo {
+    generation: u64,
+    /// Hex-encoded snapshot hash; all zeros for the genesis epoch.
+    id: String,
+}
+
+impl From<Epoch> for EpochInfo {
+    fn from(epoch: Epoch) -> Self {
+        Self {
+            generation: epoch.generation,
+            id: epoch.id_hex(),
+        }
+    }
+}
+
+#[derive(Debug, Serialize, ToSchema)]
+#[serde(rename_all = "camelCase")]
 pub(crate) struct PeerStatus {
     public_key: String,
     validated_cluster: Option<String>,
@@ -35,11 +53,16 @@ pub(crate) struct PeerStatus {
     last_seen_secs_ago: Option<u64>,
     dormant_for_secs: Option<u64>,
     has_pending_delivery: bool,
+    /// Epoch the peer last advertised; absent until it has sent a message.
+    epoch: Option<EpochInfo>,
+    /// Whether that epoch equals ours, i.e. whether we sync with this peer.
+    same_epoch: Option<bool>,
 }
 
 #[derive(Debug, Serialize, ToSchema)]
 #[serde(rename_all = "camelCase")]
 pub(crate) struct PeerListResponse {
+    local_epoch: EpochInfo,
     peers: Vec<PeerStatus>,
 }
 
@@ -73,6 +96,7 @@ pub(crate) async fn list_peers(
         .collect();
 
     let now = Instant::now();
+    let local_epoch = state.local_epoch();
     let mut peers = Vec::with_capacity(snapshot.len());
 
     for (public_key, peer_state_mutex) in snapshot {
@@ -99,11 +123,16 @@ pub(crate) async fn list_peers(
                 .map(|t| now.saturating_duration_since(t).as_secs()),
             dormant_for_secs,
             has_pending_delivery: ps.pending_outbound_sync.is_some(),
+            epoch: ps.epoch.map(EpochInfo::from),
+            same_epoch: ps.epoch.map(|epoch| epoch == local_epoch),
         });
     }
 
     peers.sort_by(|a, b| a.public_key.cmp(&b.public_key));
-    Ok(Json(PeerListResponse { peers }))
+    Ok(Json(PeerListResponse {
+        local_epoch: local_epoch.into(),
+        peers,
+    }))
 }
 
 #[utoipa::path(