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Systematic approach to finding and fixing bugs in any codebase. Use when: debugging errors, investigating unexpected behavior, fixing failing tests, or resolving production issues.
Codex 또는 Claude로 설치 이 Prompt를 복사해 Codex, Claude 또는 다른 어시스턴트에 붙여 넣으면 Skill 페이지를 검토하고 설치를 진행할 수 있습니다.
SOC 직업 분류 기준
Use when reviewing code for bugs with finder, challenger, and referee roles, especially when independent review is needed to reduce false positives.
Optimize an agent skill through bounded repeated trials, binary evaluations, targeted prompt mutations, and auditable keep/discard decisions. Use when asked to optimize, benchmark, evaluate, or systematically improve an existing skill. Produces an improved candidate skill, run artifacts, a results log, and a mutation changelog without overwriting the original.
Review uncommitted git changes for bugs/regressions via Codex MCP and present a structured report. Use when asked to review local changes or find bugs in current work. Requires Codex MCP to be configured.
Organize raw project documentation into a focused, cross-linked docs/ structure with an adaptive INDEX.md and a recommended AGENTS.md entry point. Preserve the source's natural document types; create stories only when they already exist and incremental slices only when the user wants them. Use when starting from raw documentation or restructuring scattered project docs.
Record one web application feature flow as a compact GIF using an existing Playwright installation. Use when the user asks for a visual demo, changelog artifact, documentation asset, or pull-request evidence. Creates local capture artifacts first; installation, publication, commits, uploads, and pull-request edits always require separate approval.
Coordinate specialized agent roles across complex tasks using dependency-aware planning, explicit ownership, structured handoffs, safe integration, and evidence-based quality gates. Use when work has multiple independent streams or genuinely benefits from isolated expertise; fall back transparently when the runtime cannot provide separate workers.
| name | bug-fixer |
| description | Systematic approach to finding and fixing bugs in any codebase. Use when: debugging errors, investigating unexpected behavior, fixing failing tests, or resolving production issues. |
| version | 1.0.0 |
| level | beginner |
| category | debugging |
Find and fix bugs systematically instead of guessing.
Never fix what you can't reproduce:
1. Get the exact error message or unexpected behavior
2. Find the minimal steps to trigger it
3. Confirm you can see the bug consistently
Most bugs tell you exactly what's wrong:
Error: Cannot read properties of undefined (reading 'map')
at UserList (src/components/UserList.tsx:12:24)
at Dashboard (src/app/dashboard/page.tsx:8:5)
Parse it:
.map() on undefinedUserList.tsx, line 12Work from the error outward:
1. Go to the exact file and line from the error
2. Trace the data flow backward:
- Where does this variable come from?
- What function returns it?
- What API provides it?
3. Find where expected value diverges from actual value
| Symptom | Likely Cause | Fix |
|---|---|---|
undefined is not a function | Wrong import or typo | Check import path and export name |
Cannot read property of undefined | Missing null check or data not loaded | Add optional chaining (?.) or loading state |
Too many re-renders | State update in render body | Move to useEffect or event handler |
Hydration mismatch | Server/client HTML differs | Use useEffect for client-only content |
| API returns 500 | Unhandled error in backend | Check server logs, add try/catch |
| Stale data in UI | Missing cache invalidation | Revalidate after mutation |
| Works locally, fails in CI | Environment difference | Check env vars, Node version, dependencies |
1. Make the smallest possible change that fixes the bug
2. Run the failing test / reproduce steps — confirm it passes
3. Check for similar patterns elsewhere in the code
4. Add a test that would catch this bug in the future
# Check recent changes that may have caused the bug
git log --oneline -10
git diff HEAD~3
# Find where a variable is used
grep -rn "variableName" src/
# Check TypeScript errors
npx tsc --noEmit
# Run a specific test
npx jest path/to/test --verbose
> Fix this error: TypeError: Cannot read properties of null (reading 'id')
> The login form submits but nothing happens — debug it
> Tests pass locally but fail in CI — investigate