NATS cloud-native messaging system. Covers Core NATS, JetStream persistence,
and request/reply patterns. Use for lightweight, high-performance
microservices communication.
USE WHEN: user mentions "nats", "jetstream", "cloud-native messaging", "request/reply", "subject wildcards", asks about "lightweight messaging", "microservices communication", "nats streaming"
DO NOT USE FOR: event sourcing - use `kafka` or `pulsar`; complex routing - use `rabbitmq`; AWS-native - use `sqs`; Azure-native - use `azure-service-bus`; JMS compliance - use `activemq`; persistent queues only - use dedicated broker