Replica IDs

A ReplicaId identifies which node performed an operation. It is an opaque wrapper around a string, provided by lattice_core.

import lattice_core/replica_id

let node = replica_id.new("node-a")

Most CRDTs in lattice require a ReplicaId at construction time:

• GCounter, PNCounter — to track per-replica contributions
• LWWRegister — for deterministic tie-breaking when timestamps are equal
• MVRegister, ORSet, ORMap — for causal tagging

A few types do not require one because they have no per-replica state: GSet, TwoPSet, and LWWMap.

Choose IDs that are unique across your system and across process incarnations. A stable hostname or node name alone is unsafe after a restart because peers may retain causal history for its previous run. Generate a fresh ID for every process incarnation and keep the stable name separately when other CRDTs need restart-safe identities.

lattice_presence provides this pattern directly:

import lattice_presence/presence_state

let presence = presence_state.new_incarnation("node-a")

new_incarnation preserves node-a as the stable base while generating a unique identity for the current process. Use base_replica when you need the stable name, and use same_base to compare incarnation identities by that name.