majiayu000 NW-ROOT-WHY: Toyota 5 Whys Root Cause Analysis
Wave: CROSS_WAVE Agent: Rex (nw-troubleshooter)
Overview
Systematic root cause analysis using Toyota's 5 Whys with multi-causal investigation and evidence-based validation. Investigates multiple cause branches at each level|validates solutions against all identified root causes.
Agent Invocation
@nw-troubleshooter
Execute *investigate-root-cause for {problem-statement}.
Configuration:
- investigation_depth: 5
- multi_causal: true
- evidence_required: true
Usage: DELIVER Wave Retrospective (Phase 3.5)
When invoked as part of /nw-deliver Phase 3.5, execute in order:
- Gather Inputs — Read evolution document, execution-log.json, mutation results, and git log. Gate: all available inputs loaded.
- Analyze What Worked Well — Identify practices that succeeded and document why — preserve these. Gate: at least one practice documented with rationale.
- Analyze What Improved — Identify what worked better than before and why — record as reinforcements. Gate: delta from prior execution captured.
- Analyze What Worked Badly — Apply 5 Whys root cause analysis to failures; produce actionable fix per root cause. Gate: each failure has a root cause and fix.
- Analyze What Regressed — Apply 5 Whys to anything worse than before; produce prevention action. Gate: each regression has a root cause and prevention action.
- Tag Meta-Improvements — Mark any items requiring nWave framework changes as meta-improvements. Gate: all framework-level issues flagged.
- Append Retrospective — Write retrospective section to evolution document. If clean execution (no skips, no failures, no tooling issues), generate brief summary only. Gate: evolution document updated.
Success Criteria
- All 5 WHY levels investigated with evidence
- Multi-causal branches explored at each level
- Root causes identified and validated
- Solutions address all identified root causes
- Backward chain validation performed
Next Wave
Handoff To: {invoking-agent-returns-to-workflow} Deliverables: Root cause analysis report with solutions
Examples
Example 1: Investigate test flakiness
/nw-root-why "Integration tests fail intermittently on CI but pass locally"
Rex investigates 5 WHY levels with multi-causal branches, discovers race condition in database cleanup, proposes transaction-isolated test fixtures.
Expected Outputs
docs/analysis/root-cause-analysis-{problem}.md