CLAUDE.md: Behavioral Guidelines 섹션 추가

LLM 공통 코딩 실수 감축 가이드 4섹션 (Think Before Coding /
Simplicity First / Surgical Changes / Goal-Driven Execution) 원문 영문 보존.
기존 한국어 "Claude 행동 원칙"과 보완 관계.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -575,3 +575,70 @@ docker exec trading-postgres psql -U kyu -d trading_ai -c "
 - [x] n8n DB 마이그레이션 오류 수정 완료 (51개 마이그레이션 등록)
 - [x] SSL 인증서 자동 갱신 설정 완료 (certbot.timer + deploy hook → nginx reload)
       도메인: al/cla/n8/pns/tr.kyleyang.co.kr, 훅: /etc/letsencrypt/renewal-hooks/deploy/reload-nginx.sh
+
+---
+
+## Behavioral Guidelines (LLM 공통 실수 감축)
+
+Behavioral guidelines to reduce common LLM coding mistakes. Merge with project-specific instructions as needed.
+
+Tradeoff: These guidelines bias toward caution over speed. For trivial tasks, use judgment.
+
+### 1. Think Before Coding
+Don't assume. Don't hide confusion. Surface tradeoffs.
+
+Before implementing:
+
+- State your assumptions explicitly. If uncertain, ask.
+- If multiple interpretations exist, present them - don't pick silently.
+- If a simpler approach exists, say so. Push back when warranted.
+- If something is unclear, stop. Name what's confusing. Ask.
+
+### 2. Simplicity First
+Minimum code that solves the problem. Nothing speculative.
+
+- No features beyond what was asked.
+- No abstractions for single-use code.
+- No "flexibility" or "configurability" that wasn't requested.
+- No error handling for impossible scenarios.
+- If you write 200 lines and it could be 50, rewrite it.
+
+Ask yourself: "Would a senior engineer say this is overcomplicated?" If yes, simplify.
+
+### 3. Surgical Changes
+Touch only what you must. Clean up only your own mess.
+
+When editing existing code:
+
+- Don't "improve" adjacent code, comments, or formatting.
+- Don't refactor things that aren't broken.
+- Match existing style, even if you'd do it differently.
+- If you notice unrelated dead code, mention it - don't delete it.
+
+When your changes create orphans:
+
+- Remove imports/variables/functions that YOUR changes made unused.
+- Don't remove pre-existing dead code unless asked.
+
+The test: Every changed line should trace directly to the user's request.
+
+### 4. Goal-Driven Execution
+Define success criteria. Loop until verified.
+
+Transform tasks into verifiable goals:
+
+- "Add validation" → "Write tests for invalid inputs, then make them pass"
+- "Fix the bug" → "Write a test that reproduces it, then make it pass"
+- "Refactor X" → "Ensure tests pass before and after"
+
+For multi-step tasks, state a brief plan:
+
+```
+1. [Step] → verify: [check]
+2. [Step] → verify: [check]
+3. [Step] → verify: [check]
+```
+
+Strong success criteria let you loop independently. Weak criteria ("make it work") require constant clarification.
+
+These guidelines are working if: fewer unnecessary changes in diffs, fewer rewrites due to overcomplication, and clarifying questions come before implementation rather than after mistakes.