Inject a controlled on-call operations failure

Add executable validation at the trust boundaries of humane escalation path for production AI answer platform. Reject unknown fields where they matter, bound string sizes, and coerce only after auth/signature checks when raw bytes are security-relevant. Invariant under test: missed ACK in 15m escalates; SEV1 pages dual; handoff includes timeline + next action. A TypeScript type or Python annotation is not runtime validation — pair them with parsers.

Automate the fixtures from setup, including a recreation of INC-OC-554. Assert both the visible error and the absence of side effects (no provider call, no queue write, no flag flip). Where metrics matter, assert label enums stay bounded.

Document which failures are client mistakes (4xx) versus operator/config mistakes (5xx/503). Oracle still stands: game day: primary misses ACK → secondary owns INC-OC-554 in 15m with access grant. Validation should make accidental “success with empty body” impossible for primary engineer receiving SEV2 after hours.

Property ideas: shuffled field order, Unicode edges, maximum-length strings, and replayed timestamps. Where money, identity, or citations matter, assertion messages should cite the field name. Do not snapshot entire provider payloads in tests; assert semantically. If validation fails open “to keep the demo working,” you have inverted the lab. Tie at least one CI job to the INC-OC-554 fixture so main cannot regress silently. Re-read missed ACK in 15m escalates; SEV1 pages dual; handoff includes timeline + next action after each new parser — convenience helpers love to bypass it.

Table-drive status codes and error codes so reviewers see coverage at a glance. Include a Unicode normalization case if user text is accepted. Verify that oversized bodies fail before CPU-heavy work. Where digests or versions are pinned, assert mismatch behavior. Keep golden files small enough to read in review. CI should fail on skipped tests that mark the incident fixture as xfail without a ticket link. In this chapter the product is humane escalation path for production AI answer platform, the human stakeholder is primary engineer receiving SEV2 after hours, and the incident id you design against is INC-OC-554. Re-state the oracle in your notes — game day: primary misses ACK → secondary owns INC-OC-554 in 15m with access grant — and keep the invariant visible: missed ACK in 15m escalates; SEV1 pages dual; handoff includes timeline + next action. Track ack_minutes and pages_per_week as the scoreboard. Surface under change control: PagerDuty schedule ai-answer-primary. If you only have forty minutes, finish the fixture for everyone paged for SEV3 noise → real SEV1 ignored before polishing UI. Promotion language stays ternary: promote, hold, or roll back based on evidence, not hope.