diff --git a/tests/common/sync_helpers.rs b/tests/common/sync_helpers.rs
index dbd3aca..668b5fc 100644
--- a/tests/common/sync_helpers.rs
+++ b/tests/common/sync_helpers.rs
@@ -45,6 +45,24 @@ pub async fn wait_for_new_descendant_live_generation(
     }
 }
 
+pub async fn wait_for_full_repo_live_coverage(relay: &TestRelay, timeout: Duration) {
+    let deadline = tokio::time::Instant::now() + timeout;
+    loop {
+        let log = std::fs::read_to_string(relay.log_path()).unwrap_or_default();
+        let installed = log
+            .rfind("new_full_repos=1")
+            .is_some_and(|offset| log[offset..].contains("Extended core live coverage"));
+        if installed {
+            return;
+        }
+        assert!(
+            tokio::time::Instant::now() < deadline,
+            "full-repository live coverage was not installed before the deadline"
+        );
+        tokio::task::yield_now().await;
+    }
+}
+
 // NOTE: Using rust-nostr Kind variants:
 // - Kind::GitIssue.as_u16() -> Kind::GitIssue (1621)
 // - Kind::Comment.as_u16() -> Kind::Comment (1111)
diff --git a/tests/sync/metrics.rs b/tests/sync/metrics.rs
index 1b79413..9c60bff 100644
--- a/tests/sync/metrics.rs
+++ b/tests/sync/metrics.rs
@@ -18,7 +18,8 @@ use crate::common::{
     port,
     sync_helpers::{
         create_repo_announcement, fetch_metrics, setup_announcement_on_relay,
-        wait_for_sync_connection, MetricsTestHarness, ParsedMetrics, TestClient,
+        wait_for_full_repo_live_coverage, wait_for_sync_connection, MetricsTestHarness,
+        ParsedMetrics, TestClient,
     },
     TestRelay,
 };
@@ -433,8 +434,7 @@ async fn test_live_sync_event_count() {
         .await
         .expect("Sync connection should be established");
 
-    // Additional delay to ensure purgatory promotion completes on syncing relay
-    tokio::time::sleep(Duration::from_secs(4)).await;
+    wait_for_full_repo_live_coverage(&syncing_relay, Duration::from_secs(20)).await;
 
     // Now add Layer 2 patch events (not announcements) - these are accepted immediately
     // (Layer 2 events are accepted directly to DB, no purgatory)