Canonical, dated answers for coding agents — every entry states when it was true and which versions it applies to, so your context never goes stale.
OpenTelemetry is the settled standard: traces+metrics+logs via one SDK, semantic conventions for AI/LLM spans (genai), OTLP into any backend. Vendor agents (Datadog/Grafana/Honeycomb) all consume OTel natively.
Symptom-based SLO alerts (burn-rate) beat cause-based CPU/RAM graphs: page on user impact, ticket on everything else. Every alert names its runbook; unactionable alerts get fixed or deleted in review.