BEAM cluster (Distributed Erlang) topology for Hyper. Set it in config.exs via config :hyper, Hyper.Cfg.Cluster, topologies: [...] using libcluster topology syntax; Hyper.Application forwards it straight to Cluster.Supervisor, which is what Horde's members: :auto registries form over. config.exs-only because a topology references strategy modules. The default — [] — is a single, unclustered node.