backend

The three pillars of observable systems: logs reveal events, metrics quantify health, traces map request flow. Invoke whenever task involves any interaction with observability concerns — adding logging, designing metrics, instrumenting traces, correlating signals, reviewing instrumentation, or understanding when to use which pillar.

OpenTelemetry tracing discipline: correct spans, propagation, and semantic conventions produce useful traces. Invoke whenever task involves any interaction with distributed tracing — span creation, context propagation, instrumentation, sampling configuration, or OpenTelemetry SDK setup.

Prometheus instrumentation discipline: right metric type, right name, right labels. Invoke whenever task involves any interaction with Prometheus metrics — instrumenting application code, writing PromQL queries, defining alerting or recording rules, choosing metric types, managing label cardinality, building exporters, or reviewing monitoring configuration.

StatsD metric instrumentation: push metrics over UDP, choose the right metric type, name consistently. Invoke whenever task involves any interaction with StatsD metrics — emitting counters, gauges, timers, histograms, sets, or distributions; configuring DogStatsD tags; tuning sampling rates; or integrating with Graphite, Prometheus, or Telegraf backends.