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Advanced•8–12 hours

AI Incident → Regression Forensics Lab

Turn a production incident into a minimized reproducible testcase, a root-cause slice, a permanent regression, and a verified release/rollback gate.

incident forensicsregression engineeringreplayroot-cause isolationrelease governance

Scenario

Task

A production AI incident has already been contained, but the postmortem ends as a PDF and a manual promise that it will not happen again. Convert runtime evidence into a minimal executable case, isolate the failure layer, and prove that the fix removes the cause rather than merely hiding the symptom.

Step-by-step execution

1. Freeze incident evidence

Outcome: You know exactly what was running in production at the moment of failure.

Tasks

  • →Record code, model, prompt, retrieval, tool, and policy versions
  • →Preserve a privacy-safe trace
  • →Read the authoritative final state
  • →Mark missing evidence as UNKNOWN

Checks

  • ✓Do not reconstruct missing facts from memory or model reasoning
  • ✓Evidence has a timestamp and provenance

2. Minimize the reproduction

Outcome: The failure reproduces inside a controlled harness.

Tasks

  • →Remove irrelevant context
  • →Pin deterministic dependencies
  • →Repeat multiple trials for the probabilistic layer
  • →Verify that severity is preserved

Checks

  • ✓The minimized case still reproduces the dangerous outcome
  • ✓A flaky reproduction is explicitly marked

3. Isolate root cause with ablations

Outcome: The fix targets the failure layer rather than cosmetic output symptoms.

Tasks

  • →Compare model, prompt, retrieval, tool, and policy variants
  • →Test stale-state, permission, and runtime hypotheses
  • →Measure collateral regressions
  • →Document causal confidence

Checks

  • ✓Correlation is not presented as proven root cause
  • ✓At least one hypothesis has been falsified

4. Embed the regression in the release contract

Outcome: The same incident path cannot recur unnoticed.

Tasks

  • →Add the testcase to a versioned suite
  • →Set blocking severity
  • →Run both the fix and the known-good rollback
  • →Add a monitoring signal for production recurrence

Checks

  • ✓The regression runs automatically on relevant changes
  • ✓Rollback or fallback is verified before promotion

Acceptance criteria

  • The incident has an exact release/runtime fingerprint
  • The minimized testcase reproduces the failure or honestly carries UNKNOWN status
  • Root-cause analysis includes controlled ablations
  • The permanent regression has an owner and blocking severity
  • The fix and rollback pass the same acceptance contract