IDENTITY is the durable source of truth. Reopening with a conflicting dimension is a typed error, not a footgun.

The four core enums (docs/cpp/api-reference/config.md)

cpp

enum class Metric      { cosine, euclidean, dot_product };
enum class IndexType   { graph, exact };
enum class Durability  { paranoid, standard, relaxed, ephemeral };
enum class AccessMode  { read_write, read_only };

Durability tradeoffs (docs/storage.md)

paranoid / standard — flush each write to disk before returning
relaxed — buffer in the WAL until checkpoint or close
ephemeral — no WAL attachment at all (in-process only)

Full C++ builder

cpp

elips::Config{}
    .dimension(768)
    .metric(elips::Metric::cosine)
    .index(elips::IndexType::graph)
    .graph_params({.max_connections = 32, .ef_construction = 400, .ef_search = 100})
    .durability(elips::Durability::standard)
    .access_mode(elips::AccessMode::read_write)
    .segmented_storage(true)
    .metadata_acceleration(true)
    .auto_text_embedder(true);