tuyenht Systematic Debugging
Source: obra/superpowers
Overview
This skill provides a structured approach to debugging that prevents random guessing and ensures problems are properly understood before solving.
4-Phase Debugging Process
Phase 1: Reproduce
Before fixing, reliably reproduce the issue.
## Reproduction Steps
1. [Exact step to reproduce]
2. [Next step]
3. [Expected vs actual result]
## Reproduction Rate
- [ ] Always (100%)
- [ ] Often (50-90%)
- [ ] Sometimes (10-50%)
- [ ] Rare (<10%)
Phase 2: Isolate
Narrow down the source.
## Isolation Questions
- When did this start happening?
- What changed recently?
- Does it happen in all environments?
- Can we reproduce with minimal code?
- What's the smallest change that triggers it?
Phase 3: Understand
Find the root cause, not just symptoms.
## Root Cause Analysis
### The 5 Whys
1. Why: [First observation]
2. Why: [Deeper reason]
3. Why: [Still deeper]
4. Why: [Getting closer]
5. Why: [Root cause]
Phase 4: Fix & Verify
Fix and verify it's truly fixed.
## Fix Verification
- [ ] Bug no longer reproduces
- [ ] Related functionality still works
- [ ] No new issues introduced
- [ ] Test added to prevent regression
Debugging Checklist
## Before Starting
- [ ] Can reproduce consistently
- [ ] Have minimal reproduction case
- [ ] Understand expected behavior
## During Investigation
- [ ] Check recent changes (git log)
- [ ] Check logs for errors
- [ ] Add logging if needed
- [ ] Use debugger/breakpoints
## After Fix
- [ ] Root cause documented
- [ ] Fix verified
- [ ] Regression test added
- [ ] Similar code checked
Common Debugging Commands
# Recent changes
git log --oneline -20
git diff HEAD~5
# Search for pattern
grep -r "errorPattern" --include="*.ts"
# Check logs
pm2 logs app-name --err --lines 100
Anti-Patterns
❌ Random changes - "Maybe if I change this..." ❌ Ignoring evidence - "That can't be the cause" ❌ Assuming - "It must be X" without proof ❌ Not reproducing first - Fixing blindly ❌ Stopping at symptoms - Not finding root cause