- MetricsSnapshot::capture() snapshots all metric values - assert_counter_inc(): verify counter delta after scenario - assert_gauge_eq(): verify gauge value - assert_histogram_count_inc(): verify histogram observations - assert_gauge_f64_approx(): verify f64 gauges with tolerance - print_deltas(): debug helper for all changed metrics - 9 scenario tests: ingest, query error, relevance batch, write - Histogram fields made pub for snapshot access - 515 total tests passing
