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mihaimurra001mihaimurra001/preConfigProject/.claude/skills/root-cause-analysis-and-postmortem/SKILL.md

root-cause-analysis-and-postmortem

Skill1 starsChanged 2 months agoMITView on GitHub

Use when investigating non-trivial bugs, production regressions, or recurring failures. Enforces the 5 Whys and reproduction tests before fixing.

The file

We split this skill into the rules it gives an agent

3 rules. About 0 are common, 3 are distinctive, and 0 are very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈3

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 0

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    Do not patch symptoms. Eliminate the defect permanently at its source:

    line 8
  2. Distinctive:

    Before modifying a single line of production code, write an automated test that fails by reproducing the bug.

    line 19
  3. Distinctive:

    If the test doesn't fail before your fix, you haven't reproduced the true root cause.

    line 20

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

Root Cause Analysis (5 Whys & Regression Reproduction)

Do not patch symptoms. Eliminate the defect permanently at its source:

1. The 5 Whys Ladder

  • Symptom: What was observed? (e.g., Cannot read property 'id' of undefined)
  • Why 1: Why was the variable undefined? (Service returned 204 instead of user object)
  • Why 2: Why was 204 returned? (Query filter missed tenant boundary)
  • Why 3: Why was the tenant boundary missing? (Middleware bypassed on internal RPC route)
  • Why 4: Why was it bypassed? (Route registration order placed middleware after handler)
  • Why 5 (Root Cause): Why was route registration order unprotected? (No automated test verified middleware execution order)

2. Mandatory Regression Test Reproduction

  • Before modifying a single line of production code, write an automated test that fails by reproducing the bug.
  • If the test doesn't fail before your fix, you haven't reproduced the true root cause.

3. Call-Site Audit

  • Grep all callers of the touched function or API.
  • Fix the shared contract once; never duplicate defensive checks across ten different caller files.

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