Application Errors

Application-level errors represent failures that occur during use case execution.

• UnitOfWorkError — Transaction commit or rollback failure
• EventStoreError — Event append or retrieval failure
• ConcurrencyError — Optimistic concurrency conflict
• EventBusError — Event publishing failure

When to use

Raise these errors from application code when a use case fails due to infrastructure or coordination issues. They extend the Foundation Error base class, so they carry structured messages and work with the presentation error pipeline.

On error boundaries

Application errors describe what failed during coordination. They should not encode transport or presentation concerns — those belong to outer layers.