tidaldb/.sdlc/features/pg1-instrumented-metrics/qa-results.md

QA Results — Instrumented Metrics Pipeline

Feature: pg1-instrumented-metrics Date: 2026-03-03 Status: PASS

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Test Execution Summary

Suite	Command	Result
Histogram unit tests	cargo test --lib histogram --features metrics	11/11 passed
Full lib tests	cargo test --lib --features metrics	1352/1352 passed
Integration tests	cargo test --test pg1_instrumented_metrics --features metrics,test-utils	4/4 passed

Total: 1367 tests passed, 0 failed.

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QA Plan Coverage

QP-1: Per-signal-type counters appear in /metrics output

Result: PASS

• Test prometheus_contains_per_type_counters writes 10 view signals and 5 like signals, then verifies tidaldb_signal_writes_by_type{signal_type="view"} and tidaldb_signal_writes_by_type{signal_type="like"} both appear in /metrics output.

QP-2: Latency percentile gauges (p50/p95/p99) appear after signal writes

Result: PASS

• Test prometheus_contains_percentile_gauges_after_signals writes 20 signals and verifies tidaldb_signal_write_latency_us_p50, _p95, and _p99 gauge lines appear in /metrics.

QP-3: Personalization staleness histogram recorded after user query

Result: PASS

• Test prometheus_contains_staleness_histogram_after_user_query writes a signal with user context, runs a retrieve query for that user, and verifies tidaldb_personalization_staleness_us histogram appears in /metrics.

QP-4: /diagnostics endpoint returns valid JSON with all metric keys

Result: PASS

• Test diagnostics_endpoint_returns_valid_json writes signals, hits /diagnostics, and verifies:
  • HTTP 200 response
  • Valid JSON structure (starts with {, ends with })
  • Contains keys: signal_writes_by_type, signal_write_latency_us, retrieve_latency_us, search_latency_us, personalization_staleness_us, feedback_loop_latency_us
  • Contains "view" signal type in per-type breakdown

QP-5: Histogram percentile math (unit tests)

Result: PASS

• percentile_empty_returns_none — empty histogram returns None
• percentile_single_observation — single value resolves within correct bucket
• percentile_known_distribution — 3-value distribution: p50 in [1,100], p99 >= 100
• percentile_beyond_all_bounds — observation above all bounds returns max bound (10000)
• total_count_tracks_observations — count increments correctly
• render_percentile_gauges_empty_histogram — empty histogram produces empty string
• render_percentile_gauges_format — non-empty histogram produces p50/p95/p99 gauge lines with correct TYPE annotations

QP-6: Bounded user signal map (capacity enforcement)

Result: PASS

• UserSignalTimestampMap enforces capacity via sampling-based eviction (scan 64, evict oldest)
• Verified via existing lib tests that cap is respected

QP-7: No regressions

Result: PASS

• Full lib test suite (1352 tests) passes with zero failures
• All metrics code is feature-gated behind #[cfg(feature = "metrics")] — no impact on non-metrics builds

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Clippy / Formatting

• cargo clippy --manifest-path tidal/Cargo.toml --features metrics,test-utils -- -D warnings: clean
• cargo fmt --manifest-path tidal/Cargo.toml --check: clean

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Verdict

PASS — All 7 QA plan items verified. No regressions. Feature ready for merge.