# Systematic Debugging

> Structured debugging methodology using hypothesis-driven investigation, log analysis, and bisection to isolate and resolve defects.

- Skill: `a5c-ai/systematic-debugging` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add a5c-ai/systematic-debugging`
- Raw SKILL.md: https://api.skillmd.com/api/skills/a5c-ai/systematic-debugging/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: a5c-ai (https://skillmd.com/u/a5c-ai)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/a5c-ai/systematic-debugging

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- Unexpected behavior discovered during testing
- Bug reports require investigation
- Performance issues need root cause analysis

## Process

1. **Reproduce** - Confirm the defect with a minimal reproduction
2. **Hypothesize** - Form theories about the root cause
3. **Investigate** - Systematically test hypotheses (logs, breakpoints, bisection)
4. **Isolate** - Narrow to the specific component/line
5. **Fix** - Apply targeted fix addressing root cause
6. **Verify** - Confirm fix resolves the issue without regression

## Key Rules

- Never apply fixes without understanding the root cause
- For Strike-3/post-instrumentation handoffs, do not apply a source-code fix
  until you enumerate at least 3 candidate root-cause hypotheses, give each
  hypothesis a falsifying log line or observation, and cite concrete log
  evidence for the selected fix. Use seq number when present; otherwise cite
  timestamp, log-id, or artifact path plus the exact log line. If no proposed
  fix cites a specific log line or log record, mark `needs-more-data`.
- Use web-researcher agent for unfamiliar error patterns
- Document the investigation path for future reference
- Verify that the fix does not introduce regressions

## Tool Use

Integrated into `methodologies/rpikit/rpikit-implement` (failure handling)