diff --git a/backend/src/infra.rs b/backend/src/infra.rs
index 6ef88c2..a0f480e 100644
--- a/backend/src/infra.rs
+++ b/backend/src/infra.rs
@@ -93,7 +93,7 @@ impl Infra {
             return Ok(());
         };
 
-        let is_new = relay.synced == 0;
+        let is_new = self.relay_sync_is_new(&relay).await?;
         self.sync_and_report(&relay, is_new).await;
 
         Ok(())
@@ -110,7 +110,7 @@ impl Infra {
 
         for relay in relays {
             if relay.sync_error.trim().is_empty() {
-                let is_new = relay.synced == 0;
+                let is_new = self.relay_sync_is_new(&relay).await?;
                 self.sync_and_report(&relay, is_new).await;
             } else {
                 self.schedule_relay_sync_retry(&relay.id, source).await?;
@@ -166,11 +166,20 @@ impl Infra {
             return Ok(());
         }
 
-        let is_new = relay.synced == 0;
+        let is_new = self.relay_sync_is_new(&relay).await?;
         self.sync_and_report(&relay, is_new).await;
         Ok(())
     }
 
+    async fn relay_sync_is_new(&self, relay: &Relay) -> Result<bool> {
+        if relay.synced == 1 {
+            return Ok(false);
+        }
+
+        let has_completed_sync = self.query.relay_has_completed_sync(&relay.id).await?;
+        Ok(!has_completed_sync)
+    }
+
     async fn sync_and_report(&self, relay: &Relay, is_new: bool) {
         match self.sync_relay(relay, is_new).await {
             Ok(()) => {
diff --git a/backend/src/query.rs b/backend/src/query.rs
index d231055..c1e3dd0 100644
--- a/backend/src/query.rs
+++ b/backend/src/query.rs
@@ -194,4 +194,20 @@ impl Query {
         .await?;
         Ok(rows)
     }
+
+    pub async fn relay_has_completed_sync(&self, relay_id: &str) -> Result<bool> {
+        let found = sqlx::query_scalar::<_, i64>(
+            "SELECT 1
+             FROM activity
+             WHERE resource_type = 'relay'
+               AND resource_id = ?
+               AND activity_type = 'complete_relay_sync'
+             LIMIT 1",
+        )
+        .bind(relay_id)
+        .fetch_optional(&self.pool)
+        .await?;
+
+        Ok(found.is_some())
+    }
 }