diff --git a/server/src/agent_mode.rs b/server/src/agent_mode.rs
index d10d19d8..b003c4d4 100644
--- a/server/src/agent_mode.rs
+++ b/server/src/agent_mode.rs
@@ -295,9 +295,12 @@ fn write_heartbeat(rendezvous_url: &str, port: u16) {
         return;
     };
     let now = chrono::Utc::now().timestamp() as f64;
+    let now_ms = chrono::Utc::now().timestamp_millis() as f64;
     // Advertise our crdt-sync endpoint.
     let address = format!("ws://0.0.0.0:{port}/crdt-sync");
     crdt_state::write_node_presence(&node_id, &address, now, true);
+    // Write millisecond-precision timestamp via LWW register.
+    crdt_state::write_node_metadata(&node_id, "", None, now_ms);
     slog!(
         "[agent-mode] Heartbeat written: node={:.12}… rendezvous={rendezvous_url}",
         &node_id
@@ -368,8 +371,9 @@ async fn scan_and_claim(
             .unwrap_or_default()
             .into_iter()
             .filter(|n| {
-                let now = chrono::Utc::now().timestamp() as f64;
-                n.alive && (now - n.last_seen) < CLAIM_TIMEOUT_SECS
+                let now_ms = chrono::Utc::now().timestamp_millis() as f64;
+                let last_ms = n.last_seen_ms.unwrap_or(n.last_seen * 1000.0);
+                n.alive && (now_ms - last_ms) / 1000.0 < CLAIM_TIMEOUT_SECS
             })
             .map(|n| n.node_id)
             .collect();
diff --git a/server/src/mesh.rs b/server/src/mesh.rs
index 9c8383e5..f7e16d47 100644
--- a/server/src/mesh.rs
+++ b/server/src/mesh.rs
@@ -70,10 +70,12 @@ impl MeshManager {
         let alive_peers: Vec<(String, String)> = nodes
             .into_iter()
             .filter(|n| {
+                let now_ms = now * 1000.0;
+                let last_ms = n.last_seen_ms.unwrap_or(n.last_seen * 1000.0);
                 n.alive
                     && !n.address.is_empty()
                     && n.node_id != self.our_node_id
-                    && (now - n.last_seen) < 600.0
+                    && (now_ms - last_ms) / 1000.0 < 600.0
                     && !self.is_rendezvous_peer(&n.address)
             })
             .map(|n| (n.node_id, n.address))