Quality Postmortem

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Analyze escaped defects, test suite health, and quality process gaps through structured, blameless postmortems. Every postmortem produces 1-3 concrete, tracked action items -- not vague commitments to "be more careful." The goal is systemic improvement, not individual blame.
</objective>

Quick Route

Discovery Questions

Check .agents/qa-project-context.md in the project root first — it carries quality goals, risk areas, and test suite details that anchor any postmortem. Use it and skip anything already answered there. Then clarify:

1. Do you have a regular retro cadence? Per-sprint, monthly, or only after incidents? Regular cadence catches slow-burn problems. Incident-only cadence misses patterns until they explode.

2. What triggered this postmortem? A production incident? A pattern of escaped bugs? A feeling that the test suite is not catching enough? Test suite degradation? The trigger determines the focus.

3. What data is available? Bug tracker with severity and discovery phase? CI history with pass rates? Flaky test reports? Coverage trends? Without data, postmortems devolve into opinion sessions.

4. What happened with previous postmortem action items? Were they completed? Tracked? Forgotten? If past action items are abandoned, the team has learned that postmortems do not matter. Fix the follow-through before running another postmortem.

5. Who should participate? Engineers who worked on the affected area. QA who tested (or did not test) it. Product owner if the impact was user-facing. Engineering manager if systemic changes are needed. Keep the group to 4-8 people.

6. What are the current test suite health concerns? Rising flakiness? Slow execution? Coverage gaps in critical areas? Stale quarantine? Health reviews are proactive postmortems -- they prevent incidents instead of reacting to them.

Core Principles

1. Blameless Means Systemic

Blameless does not mean "no one is accountable." It means the analysis focuses on systems, processes, and tools rather than individual performance. "Why did the system allow this defect to escape?" is a blameless question. "Why did the developer not write a test?" is a blame question that stops the analysis too early. The developer did not write a test because: the test framework was hard to use, the PR checklist did not require it, there was no pairing to transfer knowledge, or time pressure made it feel optional. Those are systemic issues with systemic fixes.

2. Focus on Patterns, Not Incidents

A single escaped bug is an anecdote. Three escaped bugs in the same feature area over two months is a pattern. Postmortems should aggregate incidents to find recurring themes: same root cause, same team, same test gap, same phase of the pipeline. Patterns are actionable. Individual incidents are just fire-fighting.

3. Every Postmortem = 1-3 Concrete Action Items

An action item is concrete when it has: a specific deliverable ("add integration tests for the coupon API"), an owner ("assigned to Alex"), a deadline ("by end of sprint 14"), and a verification method ("PR merged, tests passing in CI"). "Improve testing" is not an action item. "Write 5 integration tests for the payment service edge cases by March 30" is.

4. Track to Completion

Action items that are not tracked are not completed. Use the team's existing work tracker (Jira, Linear, GitHub Issues). Tag them (postmortem-action or equivalent). Review completion status at the start of the next postmortem. If items are consistently abandoned, either the items are too large (break them down) or they are not prioritized (make them sprint commitments).

5. Measure Improvement With Two Metrics, Not One

After implementing action items, measure whether the problem recurred. If the postmortem identified a gap in payment testing and the action was to add integration tests, track: did another payment bug escape? Without measurement, postmortems are rituals, not tools.

Track two metrics together:

• Defect escape rate (did similar bugs reappear?)
• Action-item-closure rate (what fraction of action items shipped within their committed window?)

A high closure rate with rising escape rate means the team is doing the work but doing the wrong work. A low closure rate means the postmortems are theater. Modern incident response platforms (incident.io, Rootly, FireHydrant) track action-item follow-through natively — owner, due date, completion status — so derive both numbers from what's already there before building a dashboard.

6. AI Drafts the Timeline; a Human Owns the Judgment

If your team uses AI SRE tooling (Rootly AI SRE, incident.io's AI SRE / auto-drafted post-mortems), let it draft the incident timeline and propose candidate root causes from logs and traces. Then a named blameless RCA owner — distinct from the incident commander who managed the response — runs the 5 Whys, picks the real root cause, and writes the action items. AI is good at correlation across noisy data; it is bad at deciding what mattered. Treat AI output as a starting deck, not the conclusion. For cheap timeline drafting, Sonnet 4.6 is sufficient; reserve heavier models for ambiguous causation.

Bug Pattern Analysis

Categorizing Escaped Defects

When a bug reaches production, classify it along three dimensions to identify prevention opportunities. The single-bug worksheet (Escaped Bug Analysis) lives in references/templates.md.

Dimension 1: Root Cause Category

Dimension 2: Which Test Level Should Have Caught It

Dimension 3: Prevention Opportunity

Aggregating Patterns Over Time

After analyzing 10+ escaped bugs, look for patterns:

Escaped Bug Summary: [Q1 2026]
═══════════════════════════════

Total escaped bugs: 14

By root cause:
  Logic error:          5  (36%)  ← unit tests needed
  Integration failure:  4  (29%)  ← API contract tests needed
  Data issue:           3  (21%)  ← input validation gaps
  Configuration:        2  (14%)  ← env parity issues

By area:
  Checkout:             6  (43%)  ← highest risk, needs investment
  User management:      4  (29%)
  Reporting:            2  (14%)
  Settings:             2  (14%)

By should-catch level:
  Unit:                 5  (36%)  ← developers not testing edge cases
  Integration:          4  (29%)  ← missing integration test layer
  E2E:                  3  (21%)
  Monitoring:           2  (14%)

Top action themes:
  1. Add integration tests for checkout API (covers 4 of 14 bugs)
  2. Mandate unit tests for all calculation/validation logic (covers 5 of 14)
  3. Add currency and encoding edge cases to test data fixtures (covers 3 of 14)

This aggregation reveals where investment has the highest return: fixing one systemic issue (integration tests for checkout) would have prevented 29% of all escaped bugs. Patterns that recur across multiple quarters belong in the test-strategy doc, not just the next sprint's action items — promote them so the strategy reflects where defects actually escape.

Test Suite Health Review

A proactive postmortem for the test suite itself. Conduct quarterly or when symptoms appear.

Flaky Test Trends

Flaky Test Trend Review
═══════════════════════

Current flaky rate: _____ % (target: <2%)
Trend (last 3 months):
  Month 1: _____ %
  Month 2: _____ %
  Month 3: _____ %
Direction: [ ] Improving  [ ] Stable  [ ] Worsening

Top 5 flakiest tests (by failure count):
  1. _____________________ — _____ failures — root cause: _____
  2. _____________________ — _____ failures — root cause: _____
  3. _____________________ — _____ failures — root cause: _____
  4. _____________________ — _____ failures — root cause: _____
  5. _____________________ — _____ failures — root cause: _____

Quarantine:
  Tests in quarantine:    _____ count
  Oldest quarantine:      _____ days (target: <14)
  Quarantine resolved this month: _____ count

Execution Time Trend

Track current full suite duration, 3-month trend, and the 5 slowest tests. If duration is increasing, check for: tests that can move to nightly, sequential stages that can parallelize, slow test data setup (use API instead of UI), large test files that need splitting for better shard distribution.

Coverage Gap Review

Track overall coverage (lines/branches), critical paths with insufficient coverage (payments, auth, data export should be 90%+), recently changed code without test updates (cross-reference git log --since="30 days ago" with the coverage report), and features shipped without E2E coverage.

Disabled/Skipped Test Inventory

Audit all skipped/disabled tests by age and reason. Tests skipped < 1 week are likely in progress. Tests skipped 1-4 weeks need a ticket and timeline. Tests skipped 1-3 months are overdue -- fix or delete. Tests skipped > 3 months should be deleted -- they will never be fixed. For each: fix and unskip, delete (obsolete), or move to quarantine with a ticket link.

Process Improvement Cycles

The Improvement Sprint

Dedicate a fixed portion of each sprint (10-15% of capacity) to quality improvement, drawn from postmortem action items and health review findings.

Structure:

1. IDENTIFY    — Top 3 pain points from latest retro/postmortem
2. ROOT CAUSE  — 5 Whys analysis for the #1 pain point
3. PROPOSE     — Solution with effort estimate (S/M/L)
4. IMPLEMENT   — One improvement per sprint (start small)
5. MEASURE     — Did the metric improve? By how much?
6. ITERATE     — If not improved, dig deeper. If improved, tackle #2.

5 Whys Root Cause Analysis

The 5 Whys technique peels back surface symptoms to reveal systemic causes. The key discipline: keep asking "why" until you reach a process, system, or structural cause -- not an individual's action.

Example: Payment bug escaped to production

Problem: Users were charged twice for a single purchase.

Why 1: The payment API was called twice on form submit.
Why 2: The submit button was not disabled after the first click.
Why 3: The frontend developer did not implement button disabling.
Why 4: The acceptance criteria did not mention double-submit prevention.
Why 5: The story refinement process does not include edge case review
       for payment-related stories.

Root cause: Process gap — payment stories are not reviewed for transaction
safety edge cases before development begins.

Action: Add a "Payment Safety Checklist" to the story template for any
story touching payment flows. Checklist includes: idempotency,
double-submit prevention, partial failure handling, timeout behavior.
Owner: [Product Manager] — Due: [Next sprint]

5 Whys guidelines:

• Stop when you reach something the team can change (process, tool, structure). Asking "why is the budget limited?" goes too far.
• The chain may branch -- one symptom may have multiple contributing causes. Follow the most impactful branch.
• Verify each "why" with evidence, not assumption. "The developer did not write tests" -- is that true? Check the PR. Maybe tests existed but were insufficient.
• If you reach "human error" as a root cause, you have not gone far enough. Humans make errors. The system should make errors difficult or detectable.