# NATS Reference

## Subjects
- Aggregate events: tenant.<tenant>.aggregate.<type>.<id>
- Workflow commands/events: shared helpers define exact formats

## Headers (Producers)
- tenant-id: required
- Nats-Msg-Id: idempotency key (event_id, command_id, etc.)
- x-correlation-id and correlation-id
- traceparent and trace-id

## Consumers
- AckPolicy::Explicit
- ack_wait: bounded timeout
- max_deliver: bounded
- max_ack_pending: aligned with concurrency