Can I use Catalyst for workflows that require exactly-once execution guarantees?

Catalyst provides at-least-once execution for workflow steps; exactly-once for external side effects is not automatically guaranteed. To achieve exactly-once, you must implement idempotency keys or use transactional outboxes in your activities. Catalyst persists workflow state reliably, so your orchestration logic runs exactly once per checkpoint, but external API calls may be retried. Design your system to handle duplicates safely.