refactor

allowed-tools	["Read","Edit","Grep","Glob","Bash"]
description	Use when code smells are identified and tests or specs exist to refactor without changing behavior.
name	refactor
trigger	리팩토링, 코드 정리, 함수 분리, 코드 스멜 제거, refactor, extract method, rename, simplify, long method, duplicated code, god object, feature envy, magic number, nested conditionals, dead code, guard clause, introduce constant, parameter object, code smell fix, 테스트 기반 리팩토링, 안전 리팩토링, refactoring workflow, extract function, remove duplication, clean code, 코드 개선, 구조 개선, primitive obsession, inappropriate intimacy, single responsibility, 동작 보존, 증분 리팩토링, 코드 중첩 제거, 마직넘버, 상수 추출, 파라미터 객체, 캡슐화 개선, 위임 패턴, 책임 분리, 긴 함수 분리, 중복 로직 제거, 신비한 숫자, 중첩 조건문 평탄화, 사각지대 코드 삭제, 테스트 없는 리팩토링 금지, 코드 냄새 고치기, 리팩토링 가이드, refactoring rules, code smell catalog, extract method pattern, guard clause pattern, introduce parameter object, remove dead code, simplify logic, improve readability, code hygiene, refactoring checklist, safe refactoring, incremental refactoring, behavior preservation, test driven refactoring, TDR, 리팩토링 전략, 코드 리팩토링 단계, 리팩토링 원칙, 코드 구조 최적화, 함수 추출, 조건문 단순화, 상수화, 도메인 타입 도입, 값 객체, delegation, encapsulation, 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Quick Reference

• 진행 전 조건: 테스트나 명세 확인 없이는 시작 금지
• 처리 범위: 한 번에 하나의 코드 스멜만 집중 해결
• 변경 원칙: 외부 인터페이스 변경 없이 내부 구조만 개선
• 안전 검증: 각 변경 직후 테스트 통과 확인 및 커밋 필수
• 완료 판단: 모든 기존 테스트 통과 및 성능 저하 없음 확인

PREPARE

Before refactoring:

1. 테스트 확인

   # 테스트 존재 여부 확인
   find . -name "*.test.*" -o -name "*_test.*" -o -name "*spec*" | head -10
   

   테스트 없으면 동작 명세를 먼저 작성하거나 사용자에게 확인.

2. 브랜치 생성

   git checkout -b refactor/{describe-smell}
   

3. 현재 상태 커밋 — commit 스킬 패턴으로 안전 기점 확보

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IDENTIFY

10가지 코드 스멜 카탈로그

스멜	신호	해결 방향
Long method	함수 40줄+	책임별 Extract Method
Duplicated logic	유사 블록 3회+	공통 함수 추출
God object	클래스 10+ 메서드	Single Responsibility로 분리
Excessive parameters	파라미터 4개+	파라미터 객체로 그룹화
Feature envy	A가 B의 데이터를 자주 사용	로직을 B로 이동
Primitive obsession	원시 타입 남용	도메인 타입/값 객체 도입
Magic values	의미없는 숫자/문자열	상수/enum으로 교체
Nested conditionals	if 3단계+ 중첩	Guard clause로 평탄화
Dead code	미호출 함수/변수	완전 삭제
Inappropriate intimacy	과도한 내부 접근	위임(delegation)으로 캡슐화

PICK ONE — 이번 세션에서 처리할 스멜 하나만 선택한다.

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REFACTOR

핵심 원칙

1. 동작 보존 — 외부 인터페이스 변경 없음
2. 증분 진행 — 한 번에 한 가지만 변경
3. 테스트 통과 유지 — 각 변경 후 즉시 확인

기법별 가이드

Extract Method (Long method 해결):

긴 함수 → 의도를 드러내는 이름의 작은 함수들로 분리
변경 전: one_big_function() { step1; step2; step3; }
변경 후: handle_request() { validate(); process(); respond(); }

Guard Clause (Nested conditionals 해결):

중첩 if → 조기 반환으로 평탄화
변경 전: if (ok) { if (valid) { if (auth) { ... }}}
변경 후: if (!ok) return; if (!valid) return; if (!auth) return; ...

Introduce Named Constant (Magic values 해결):

변경 전: if (status == 3) { ... }
변경 후: MAX_RETRY = 3; if (status == MAX_RETRY) { ... }

각 기법 적용 후:

# 테스트 실행
<test command>
# 통과하면 커밋
git add -A && git commit -m "refactor: <what changed>"

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VERIFY

empirical-validation 스킬로 최종 검증:

• 모든 기존 테스트 통과
• 인터페이스 변경 없음 (git diff main -- *.d.ts 또는 API 명세 확인)
• 성능 저하 없음 (해당 시)

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관련 스킬

• commit — 각 안전 상태 커밋 프로토콜
• clean — shellcheck/shfmt 코드 품질 (shell scripts)
• verifier — 구현 완료 후 전체 검증
• empirical-validation — 경험적 검증 (테스트 실행 + 결과 확인)

Iron Laws

NO REFACTOR WITHOUT TEST OR SPEC FIRST NO MULTI-SMELL REFACTOR WITHOUT SINGLE-FOCUS FIRST NO COMMIT WITHOUT TEST PASS FIRST NO BEHAVIOR CHANGE WITHOUT INTERFACE PRESERVATION FIRST NO NEXT STEP WITHOUT EMPIRICAL VALIDATION FIRST