Command-side replica

Intent

Replicate reference data into a command service so it can validate/execute commands without synchronous cross-service reads.

Use when

• Command handling requires data owned elsewhere, and synchronous reads add latency/failure coupling.
• You can tolerate eventual consistency in replicated reference data.

Avoid / watch-outs

• Clearly define staleness rules and how you resolve conflicts when the replica lags.
• Replication needs monitoring; stale replicas create subtle correctness bugs.

Skill mapping

• architecture: pick replication mechanism (events/outbox/CDC) and ownership.
• spec: define staleness tolerance and conflict/validation semantics.
• observability: replica lag metrics and alerting.
• testing: tests for stale-data behavior and reconciliation paths.