test

                bin_write_str(oss, m.media_kind);

                bin_write_str(oss, m.content_type);

                bin_write_str(oss, m.created_at);

                bin_write_u64(oss, m.size_bytes);

                // Fetch raw data from cluster (per-media key)

                std::vector<uint8_t> raw;

                const_cast<Cluster&>(cluster_).fetch("media:" + m.id, raw);

                if (m.size_bytes > 0) {

                // Write actual fetched size — not m.size_bytes — so the

                // header always matches the data that follows.  If the

                // fetch failed the entry gets size 0 (metadata preserved,

                // no corrupt zero-padding).

                bin_write_u64(oss, static_cast<std::uint64_t>(raw.size()));

                if (!raw.empty()) {

                        // Write exactly size_bytes to match the header.

                        // If the fetched data differs in length (e.g. degraded

                        // cluster), truncate or pad to maintain format integrity.

                        auto write_len = std::min<std::uint64_t>(raw.size(), m.size_bytes);

                    oss.write(reinterpret_cast<const char*>(raw.data()),

                                  static_cast<std::streamsize>(write_len));

                        if (write_len < m.size_bytes) {

                            std::vector<uint8_t> pad(m.size_bytes - write_len, 0);

                            oss.write(reinterpret_cast<const char*>(pad.data()),

                                      static_cast<std::streamsize>(pad.size()));

                        }

                    } else {

                        // Fetch failed — pad with zeros to maintain format integrity

                        std::vector<uint8_t> zeros(m.size_bytes, 0);

                        oss.write(reinterpret_cast<const char*>(zeros.data()),

                                  static_cast<std::streamsize>(zeros.size()));

                    }

                              static_cast<std::streamsize>(raw.size()));

                }

            }

        }