- JSONFormatter, ContextVars, set_research_run_id() with short logger names - self-built Counter/Histogram/Gauge system (no external deps) - Prometheus text export at /metrics - Request logging middleware with X-Request-ID - Metrics instrumentation: search_queries, sources_fetched, claims, contradictions - Histograms: research_duration, llm_request_duration - Gauge: active_research_runs - 13 + 21 = 34 tests