obs-traces

Follow one request across services — when logs say 'slow' and metrics say 'sometimes', the trace says where. Read waterfalls, find the span that ate latency, and correlate trace ids with logs. Backends: Tempo (TraceQL) and Cloud Trace on GCP. Triggers: 'trace this request', 'where did the latency go', 'open this trace id'. A request or correlation id with no trace id starts in obs-logs. Not for trace instrumentation (obs-pipeline).