Inject a controlled runbooks failure

Add executable validation at the trust boundaries of executable queue-backlog runbook for embedding ingestion pipeline. 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: every command is copy-pasteable; mutating steps need change ticket; verify after each step. A TypeScript type or Python annotation is not runtime validation — pair them with parsers.

Automate the fixtures from setup, including a recreation of INC-INGEST-9021. 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: drill INC-INGEST-9021: lag 60→5 minutes in ≤ 25m following runbook v1.4. Validation should make accidental “success with empty body” impossible for secondary on-call clearing ingest.lag_minutes > 45.

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-INGEST-9021 fixture so main cannot regress silently. Re-read every command is copy-pasteable; mutating steps need change ticket; verify after each step 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 executable queue-backlog runbook for embedding ingestion pipeline, the human stakeholder is secondary on-call clearing ingest.lag_minutes > 45, and the incident id you design against is INC-INGEST-9021. Re-state the oracle in your notes — drill INC-INGEST-9021: lag 60→5 minutes in ≤ 25m following runbook v1.4 — and keep the invariant visible: every command is copy-pasteable; mutating steps need change ticket; verify after each step. Track drill_completion_minutes and lag_minutes as the scoreboard. Surface under change control: ingest worker + queue metrics. If you only have forty minutes, finish the fixture for runbook says 'restart something' without naming deployment or verifying lag before polishing UI. Promotion language stays ternary: promote, hold, or roll back based on evidence, not hope.