Observability

Push dead-letter rate (PushDeadLetterRateHigh), stream lag, device token hygiene, inbox backlog.

Logs are JSON in production. The correlation id is header X-Request-Id, MDC key traceId. Search in Grafana Logs (splick-logs) or Trace Explorer (splick-trace-explorer).

Prometheus scrapes /actuator/prometheus on this service port as part of the spring-apps job. Dashboards: Service Health, Use case health, Slow APIs, Async Pipeline.