syncUserLogs: delegate to backfillUserLogs when user has no rows

functions.php

@@ -102,6 +102,18 @@ function syncUserLogs($user) {
 
     $pdo = getDatabaseConnection();
 
+    $stmt = $pdo->prepare('SELECT COUNT(*) FROM vault WHERE user = :user');
+    $stmt->bindValue(':user', $user);
+    $stmt->execute();
+    $userRowCount = (int)$stmt->fetchColumn();
+
+    // If the user has zero rows (not the global dbNew, but per-user empty),
+    // delegate to backfillUserLogs which walks the full prev chain.
+    if ($userRowCount === 0) {
+        backfillUserLogs($user);
+        return;
+    }
+
     $stmt = $pdo->prepare('SELECT MAX(timestamp) AS max_ts FROM vault WHERE user = :user');
     $stmt->bindValue(':user', $user);
     $stmt->execute();