Add observability and tests

Instrument Prometheus+Grafana board for AI answer API golden signals so SRE watching error budget during a model bump can answer: demand, errors, latency/age, saturation. Emit fields needed by alert_precision on game-day ≥ 0.9 and scrape_up == 1 with bounded labels. Sample successful high-volume traces; keep errors and rollout transitions denser within policy.

Define at least one alert that would fire for MON-TENANT-BLIND-9, with a for/pending window that survives deploy blips. Missing scrape or missing revision labels must not look like health. Include a trace/log example id format you will actually search.

Add a unit/integration check that metrics increment on the happy path and on the dashboard averages hide tenant Acme 40% error rate branch. Store machine-readable output in CI artifacts when practical.

Cardinality discipline: tenant and revision are usually enough; raw question text is not a label. Exemplars or trace links beat screenshots alone when debugging MON-TENANT-BLIND-9. Define who owns alert fatigue review. If you export to a vendor, record retention and access. Synthetic probes should use non-sensitive fixtures and still exercise GET /metrics. Practice the query you will type at 2am once, while calm.

Document the exact PromQL or log query in the runbook stub for this service. Verify histograms have buckets around your SLO target. Add a canary synthetic check that exercises the oracle path every few minutes in staging. Confirm that PII redaction happens before export. Track build/version as a label on the golden signals. Delete noisy debug logs before they become accidental product dependencies. In this chapter the product is Prometheus+Grafana board for AI answer API golden signals, the human stakeholder is SRE watching error budget during a model bump, and the incident id you design against is MON-TENANT-BLIND-9. Re-state the oracle in your notes — inject 5% 500s for 10m → Alert AnswerErrorBurn fires; recovery clears within 15m — and keep the invariant visible: alerts require multi-window evidence; missing scrape ≠ healthy silence. Track alert_precision on game-day ≥ 0.9 and scrape_up == 1 as the scoreboard. Surface under change control: GET /metrics. If you only have forty minutes, finish the fixture for dashboard averages hide tenant Acme 40% error rate before polishing UI. Promotion language stays ternary: promote, hold, or roll back based on evidence, not hope.