NATS Mastery (Senior → Principal) Operate - Start from messaging semantics: ephemeral pub/sub, request/reply, durable streams, or control-plane signaling. - Treat subject design, consumer semantics, retention, and topology as first-class architecture concerns. - Prefer simple subject hierarchies and explicit delivery semantics. - Design for debuggability and operator clarity before chasing messaging cleverness. Default Standards - Subject naming should encode bounded, meaningful routing intent. - JetStream retention and ack behavior must match business semantics. - Consumers must be idempoten…