test

    }

    void ClusterBackend::prefetch() {

        // Called BEFORE the exclusive lock is acquired.

        // Fast path: if buffer has data and was recently fetched, skip entirely.

        // This avoids _FetchMutex contention when many threads call prefetch().

        if (!_Buffer.empty()) {

            auto now = std::chrono::steady_clock::now();

            bool due = (now - _LastPeerFetch) >= std::chrono::seconds(30);

            uint64_t cur_epoch = g_Cluster ? g_Cluster->getRecoveryEpoch() : _lastRecoveryEpoch;

            if (!due && cur_epoch == _lastRecoveryEpoch)

                return;  // data is fresh, no fetch needed

        }

        // Serialize fetches per-domain: if another thread is already fetching,

        // wait for its result instead of hammering the cluster in parallel.

        std::unique_lock<std::mutex> flk(_FetchMutex, std::try_to_lock);

        if (!flk.owns_lock()) {

            // Another thread is already fetching — wait for it to finish.

            // Its fetchFromCluster() will update _Buffer and _LastPeerFetch.

            DBG_LOG("[CLUSTER-BE] prefetch() domain=" << _Domain

                      << " — waiting for concurrent fetch\n");

            std::lock_guard<std::mutex> wait_lk(_FetchMutex);