Aggregate

Intent

Define a consistency boundary (DDD aggregate) that enforces invariants for a cluster of domain objects.

Use when

• You need to enforce invariants/transactions within a clear boundary.
• You want to prevent “distributed invariants” that would require cross-service transactions.

Avoid / watch-outs

• Keep aggregates small; large aggregates reduce concurrency and create performance bottlenecks.
• Don’t let “read model needs” expand your aggregate; use CQRS/read models instead.

Skill mapping

• architecture: define service and data ownership boundaries aligned to aggregates.
• spec: document invariants and expected failures when invariants are violated.
• design: model aggregates with explicit command handling and typed errors.