why - Claude MCP Skill

# Five Whys Analysis

Apply Five Whys root cause analysis to investigate issues by iteratively asking "why" to drill from symptoms to root causes.

## Description

Iteratively ask "why" to move from surface symptoms to fundamental causes. Identifies systemic issues rather than quick fixes.

## Usage

`/why [issue_description]`

## Variables

- ISSUE: Problem or symptom to analyze (default: prompt for input)
- DEPTH: Number of "why" iterations (default: 5, adjust as needed)

## Steps

1. State the problem clearly
2. Ask "Why did this happen?" and document the answer
3. For that answer, ask "Why?" again
4. Continue until reaching root cause (usually 5 iterations)
5. Validate by working backwards: root cause → symptom
6. Explore branches if multiple causes emerge
7. Propose solutions addressing root causes, not symptoms

## Examples

### Example 1: Production Bug

```
Problem: Users see 500 error on checkout
Why 1: Payment service throws exception
Why 2: Request timeout after 30 seconds
Why 3: Database query takes 45 seconds
Why 4: Missing index on transactions table
Why 5: Index creation wasn't in migration scripts
Root Cause: Migration review process doesn't check query performance

Solution: Add query performance checks to migration PR template
```

### Example 2: CI/CD Pipeline Failures

```
Problem: E2E tests fail intermittently
Why 1: Race condition in async test setup
Why 2: Test doesn't wait for database seed completion
Why 3: Seed function doesn't return promise
Why 4: TypeScript didn't catch missing return type
Why 5: strict mode not enabled in test config
Root Cause: Inconsistent TypeScript config between src and tests

Solution: Unify TypeScript config, enable strict mode everywhere
```

### Example 3: Multi-Branch Analysis

```
Problem: Feature deployment takes 2 hours

Branch A (Build):
Why 1: Docker build takes 90 minutes
Why 2: No layer caching
Why 3: Dependencies reinstalled every time
Why 4: Cache invalidated by timestamp in Dockerfile
Root Cause A: Dockerfile uses current timestamp for versioning

Branch B (Tests):
Why 1: Test suite takes 30 minutes
Why 2: Integration tests run sequentially
Why 3: Test runner config has maxWorkers: 1
Why 4: Previous developer disabled parallelism due to flaky tests
Root Cause B: Flaky tests masked by disabling parallelism

Solutions: 
A) Remove timestamp from Dockerfile, use git SHA
B) Fix flaky tests, re-enable parallel test execution
```

## Notes

- Don't stop at symptoms; keep digging for systemic issues
- Multiple root causes may exist - explore different branches
- Document each "why" for future reference
- Consider both technical and process-related causes
- The magic isn't in exactly 5 whys - stop when you reach the true root cause
- Stop when you hit systemic/process issues, not just technical details
- Multiple root causes are common—explore branches separately
- If "human error" appears, keep digging: why was error possible?
- Document every "why" for future reference
- Root cause usually involves: missing validation, missing docs, unclear process, or missing automation
- Test solutions: implement → verify symptom resolved → monitor for recurrence