# Systematic Debugging

> 4-phase root cause process before any fix. Use whenever you encounter an error.

- Skill: `archieindian/systematic-debugging` (Agent Skill)
- Install (CLI): `npx skillmds@latest add archieindian/systematic-debugging`
- Raw SKILL.md: https://api.skillmd.com/api/skills/archieindian/systematic-debugging/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: archieindian (https://skillmd.com/u/archieindian)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/archieindian/systematic-debugging

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# Systematic Debugging

Never guess at fixes. Find the root cause first.

## Phase 1: Understand the Error
- Read the full error message
- Note the exact file, line, error type
- Reproduce the error reliably
- Write: 'The error is: [exact error] at [location] when [trigger].'

## Phase 2: Hypothesize
Generate at least 2 hypotheses. For each: what evidence supports it? What would disprove it?

## Phase 3: Test Hypotheses
Test each hypothesis with the minimum change to confirm or deny it.
- Add a log line, not a fix
- Test one variable at a time

## Phase 4: Fix and Verify
1. Write the fix
2. Verify the original error is gone
3. Verify no new errors
4. Add a test that would have caught this bug