test

            return;

        }

        // Serialize fetches per domain

        // Serialize fetches per domain — don't block if another thread is fetching

        std::unique_lock<std::mutex> flk(cache->fetch_mutex, std::try_to_lock);

        if (!flk.owns_lock()) {

            std::lock_guard<std::mutex> wait_lk(cache->fetch_mutex);

            // Another thread is already fetching — use cached data, don't wait

            if (!cache->buffer.empty()) {

                _Buffer = cache->buffer;

                _ClusterDataExists.store(_Buffer.size() > sizeof(AuthHeader));

    ClusterBackend::ClusterBackend(const char *domain, size_t version, const char *filepath)

        : _Domain(domain), _Pos(0), _Dirty(false)

    {

        // Check if the local block store already has shards for this domain.

        // Try the shared domain cache first — no network I/O needed.

        // This is critical: the constructor must NOT call pclient_->retrieve()

        // because the push_worker may hold pclient_->mutex_ for seconds,

        // blocking this constructor and causing HTTP timeouts.

        if (g_Cluster && g_Cluster->isRunning()) {

            auto cache = getDomainCache();

            if (!cache->buffer.empty()) {

                _Buffer = cache->buffer;

                _ClusterDataExists.store(true);

            } else {

                // No cached data yet — check local block store (no network)

                uint64_t dgid = domainGroupId();

                auto &store = g_Cluster->getStore();

                auto blocks = store.list_blocks(dgid);

                if (!blocks.empty())

                    _ClusterDataExists.store(true);

            }

        // Try to fetch existing data from cluster (single attempt, non-blocking).

        // If peers aren't reachable yet, lock() will fetch on first use.

        fetchFromCluster();

        }

        if (_Buffer.empty()) {

            // Initialize with a fresh header locally.

            // Do NOT push to cluster — we may have failed to fetch existing data

            // and pushing an empty header would overwrite real data on other nodes.

            AuthHeader head;

            head.Version = version;

            head.Revesion = 0;