Function managed_cluster_replica_name 

pub fn managed_cluster_replica_name(index: u32) -> String

The canonical name of the index-th (zero-based) replica of a managed cluster.

A managed cluster’s replicas are derived from its replication_factor: for a factor of N they are named r1 through rN.

The catalog-open reconciler that materializes builtin replicas converges on this rule, CREATE CLUSTER names its replicas by it, and the unmanaged-to-managed conversion validates the existing names against it. The cluster controller deliberately does not: its ReplicaNameGen picks names that avoid the observed set, which is why it drops by observed id rather than by derived name.