5-whys

5-Whys Postmortem

Model

• Preferred: claude-haiku-4.5
• Premium-exhausted fallback: claude-sonnet-4.6 for severity gates (i)-(iii) or disputed root cause
• Source of truth: Model Routing Matrix in .github/skills/dev-session/SKILL.md

.github/copilot-instructions.md §5-whys mistake protocol is authoritative for trigger logic and severity gates.

Template

Use this structure:

1. Problem statement
2. Why 1
3. Why 2
4. Why 3
5. Why 4
6. Why 5
7. Root cause
8. Action items (specific, testable, owner/trigger where possible)

Output block (required)

FIVE_WHYS_POSTMORTEM: <root cause>
Problem statement: <...>
Why 1: <...>
Why 2: <...>
Why 3: <...>
Why 4: <...>
Why 5: <...>
Root cause: <...>
Action items:
- <...>

Output destinations (both required)

• GitHub issue comment — must begin with FIVE_WHYS_POSTMORTEM:
• store_memory fact/content — must begin with FIVE_WHYS_POSTMORTEM: