claude-skills/engineering/skills/chaos-engineering/assets/postmortem_template.md
Claude 23eefc2e9a
feat(skills): ship chaos-engineering (Phase 3 — resilience testing discipline)
Phase 3 of the multi-skill build effort. Same 14-step pipeline. Composes
explicitly with feature-flags-architect (kill switches as abort triggers)
and kubernetes-operator (operators are common chaos targets).

## What landed

### New skill: engineering/chaos-engineering

End-to-end chaos engineering discipline. Published as BOTH:
- Standalone plugin: engineering/chaos-engineering/
- Bundled mirror:    engineering/skills/chaos-engineering/

3 stdlib-only Python tools (Karpathy complexity 95/100 — best in portfolio):
- experiment_designer.py        — generates structured plans with hypothesis,
                                   steady-state, blast radius, abort criteria,
                                   rollback. Refuses to render plans without
                                   abort criteria (exit code 1).
- blast_radius_calculator.py    — computes affected users + error budget
                                   consumption + GREEN/YELLOW/RED risk score.
                                   Validates inputs (0 ≤ traffic-share ≤ 1).
- experiment_postmortem.py      — blameless postmortems from plan + result log;
                                   detects blame-laden language ("fault of",
                                   "should have known", "stupid", etc.) and
                                   warns at write time.

4 reference docs:
- chaos_principles.md      — 4 founding principles + 5th abort principle,
                              maturity model, history, when-to-start checklist
- experiment_design.md      — 7-section plan structure, pre-flight checklist,
                              time-boxing, escalation
- attack_taxonomy.md        — 7 attack types (latency / error / resource /
                              network-partition / dependency-failure / time-skew
                              / infrastructure) with magnitudes and tooling
- tooling_landscape.md      — Chaos Toolkit / Mesh / Litmus / Gremlin / AWS FIS
                              / DIY decision tree

Templates:
- experiment_template.md    — fill-in plan with all 7 sections
- postmortem_template.md    — blameless postmortem structure

Plus: SKILL.md (213 lines), README.md, /chaos-experiment slash command.

### Audit verdict (evidence-based)

Closest existing skills:
- engineering-team/incident-response — for actual incidents, not prevention
- engineering-team/red-team — adversarial; different goal (find attack paths)
- engineering-team/threat-detection — hunting; different goal
- engineering/observability-designer — measurement, not fault injection
None cover the chaos-engineering discipline (hypothesis-driven fault injection
with bounded blast radius). Verdict: BUILD. Gap is real and tooling-shaped.

### Composition story (Phase 1+2+3 form a stack)

```
feature-flags-architect.kill_switch_audit.py
  ↓ defines kill switches that ↓
chaos-engineering.experiment_designer.py
  ↓ designs experiments against ↓
kubernetes-operator (and other targets)
```

Together: a complete progressive-delivery + resilience-testing stack.

### Marketplace / registry

- marketplace.json: chaos-engineering registered as standalone plugin
- engineering-advanced-skills bundle: 47 → 48 skills, version → 2.4.2
- engineering/.claude-plugin/plugin.json: version + skill list updated
- mkdocs.yml: nav entry under "Engineering - POWERFUL"
- docs/skills/engineering/chaos-engineering.md: docs page (manual,
  pending generate-docs.py classification fix)
- docs/commands/chaos-experiment.md: auto-generated
- .codex/, .gemini/: synced

### Karpathy-coder gates

- complexity_checker (strict): 95/100 average — BEST score in the new
  portfolio. Only 1 WARN (depth 5 in blast_radius_calculator.py validation
  branches; the other 2 scripts hit no findings whatsoever).
- All 1666 tests pass (was 1648; added 18 for the new skill).
- mkdocs build --strict: succeeded in 13.33s.

### Verifiable success criteria (all green)

✓  scripts/*.py --help     → exit 0 for all 3 scripts
✓  SKILL.md frontmatter    → name + description + tags + compatible_tools
✓  plugin.json schema      → 8 fields exact (verified by check_plugin_json.py)
✓  sync_skill_bundles      → standalone ↔ bundled mirror in sync
✓  marketplace.json        → standalone entry + bundle counts updated
✓  generate-docs.py        → command page generated (skill page manual)
✓  mkdocs build --strict   → succeeded
✓  cross-tool sync         → codex + gemini synced
✓  pytest tests/           → 1666 passed, 0 failed
✓  CHANGELOG.md            → [Unreleased] entry expanded for Phase 3
✓  Self-test (RED case)    → 50% blast radius on 99.9% baseline correctly
                             classifies as RED (17.33% of monthly budget) and
                             returns ABORT recommendation
✓  Composition test        → references named skills explicitly compose

## Phase 1+2+3 cumulative

- 3 new skills: feature-flags-architect, kubernetes-operator, chaos-engineering
- 9 new Python tools (all stdlib, all <200 LOC, average complexity 90/100)
- 12 new reference docs (~250-500 lines each)
- 3 new slash commands (/flag-cleanup, /operator-audit, /chaos-experiment)
- 2 repo-infrastructure scripts (sync_skill_bundles, check_plugin_json)
- 1 pre-existing test fix (full-page-screenshot CI red)

## Files

- engineering/chaos-engineering/                                (new standalone plugin)
- engineering/skills/chaos-engineering/                         (new bundled mirror)
- commands/chaos-experiment.md                                  (new slash command)
- docs/skills/engineering/chaos-engineering.md                  (new docs page)
- docs/commands/chaos-experiment.md                             (auto-generated)
- mkdocs.yml                                                    (nav entries)
- .claude-plugin/marketplace.json                               (registered)
- engineering/.claude-plugin/plugin.json                        (bundle bumped)
- CHANGELOG.md                                                  ([Unreleased] expanded)
- .codex/, .gemini/                                             (cross-tool sync)

https://claude.ai/code/session_01Dq12xJakFRxwaoU8Pqejdm
2026-05-09 21:24:16 +00:00

1.5 KiB

Chaos Experiment Postmortem

Identity

  • Experiment: <experiment_id>
  • Date: <YYYY-MM-DD>
  • Target: <service>
  • Owner: <handle@team>
  • Postmortem facilitator: <handle@team>

Hypothesis

<hypothesis from the plan>

Outcome

  • Held — hypothesis confirmed
  • Refuted — hypothesis disproven
  • Inconclusive — could not tell

Timeline

Time Event
T-5min Started baseline measurement
T+0 Attack injected
T+? <observation>
T+? <observation>
T+N Attack ended (or aborted)
T+N+2 Steady state recovered

What we learned

<at least one concrete learning — required>

What surprised us

<unexpected observations; "nothing surprised us" is a signal that you didn't push hard enough>

What failed

<things that broke during the experiment that shouldn't have>

What held

<things that worked as expected — confidence-building data points>

Root causes (if any failures)

<technical analysis without blame>

Follow-up actions

Action Owner Due Status
<concrete action> <@owner> <date> [ ]
<concrete action> <@owner> <date> [ ]

Every experiment should produce ≥1 follow-up. If none — re-examine whether you tested anything new.

Next experiment

<what's the next experiment that builds on this learning?>

Stakeholder summary (1-2 sentences)

<for the team channel; describe outcome and biggest learning>