Inject a controlled postmortems failure

Add executable validation at the trust boundaries of blameless postmortem for tokenizer-induced summarization outage. 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: actions are owned, dated, verifiable; contributing factors include process not only code. A TypeScript type or Python annotation is not runtime validation — pair them with parsers.

Automate the fixtures from setup, including a recreation of INC-SUM-TOK-87. 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: postmortem published with 3 actions; action A1 verified by test that fails on old tokenizer pin. Validation should make accidental “success with empty body” impossible for EM facilitating review of INC-SUM-TOK-87.

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-SUM-TOK-87 fixture so main cannot regress silently. Re-read actions are owned, dated, verifiable; contributing factors include process not only code 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 blameless postmortem for tokenizer-induced summarization outage, the human stakeholder is EM facilitating review of INC-SUM-TOK-87, and the incident id you design against is INC-SUM-TOK-87. Re-state the oracle in your notes — postmortem published with 3 actions; action A1 verified by test that fails on old tokenizer pin — and keep the invariant visible: actions are owned, dated, verifiable; contributing factors include process not only code. Track actions_closed_on_time and recurrence_90d as the scoreboard. Surface under change control: summarization service. If you only have forty minutes, finish the fixture for action 'be more careful' with no owner — recurrence in 6 weeks before polishing UI. Promotion language stays ternary: promote, hold, or roll back based on evidence, not hope.