refactor(topics): 멀티 에이전트용 지식 재편 — _Common(공통 기본기) + Domain_* 구조

에이전트 8종(대화형/프로그래머 C·S/디자이너/설계자/기획자/QA/PD/PM)에게
[공통 기본 능력 + 롤별 Specialty] 2층으로 지식을 주입하기 위한 재분류.
문서 내용·포맷은 무수정, 폴더 이동만 (6,372개 문서 수 보존 확인).

- Topic_Programming → Domain_Programming (내부 구조 보존)
- Topic_Graphic → Domain_Design
- Topic_Business → Domain_Product
- Topic_General → Domain_General
- _Common 신설: Math(구 Topic_Math_Specialty), Reasoning(구 General/From_Thinking & Reasoning),
  Reasoning_Creativity(구 General/From_창의성), Communication(Poetic_Blog_Writing + From_writing)
- 타 도메인의 From_* 폴더는 유지 (출처 표기일 뿐, 이미 도메인에 맞게 분류된 문서)
- 빈 폴더 정리 (memory/procedures)
- 에이전트→폴더 매핑은 workspace의 .astra/agent-knowledge-map.json (9개 에이전트)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

10_Wiki/Topics/Domain_Programming/Topic_PHP/PHP_Sessions.md

@@ -0,0 +1,75 @@
+---
+id: php-sessions
+title: "PHP Sessions"
+category: "Programming_Language"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["session_start()", "$_SESSION", "PHP 세션"]
+duplicate_of: ""
+source_trust_level: "B"
+confidence_score: 0.9
+created_at: 2026-07-04
+updated_at: 2026-07-04
+review_reason: ""
+merge_history: []
+tags: ["php", "programming", "w3schools", "sessions"]
+raw_sources: ["https://www.w3schools.com/php/php_sessions.asp"]
+applied_in: []
+github_commit: ""
+---
+
+# [[PHP Sessions]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+A session's ONLY client-side footprint is a small random ID stored in a `PHPSESSID` cookie — the actual session DATA lives entirely on the server (typically in a temp file), meaning sessions are fundamentally more secure than cookies for sensitive data, since the browser never holds the real information, just a lookup key. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **Session** — solves HTTP's statelessness by storing per-user data server-side, linked via a client-side ID cookie. [S1]
+- **`session_start()`** — must be called at the very beginning of every script using sessions, before ANY HTML output or whitespace. [S1]
+- **`$_SESSION`** — superglobal for storing/accessing session variables. [S1]
+- **`unset($_SESSION["key"])`** — removes one session variable. [S1]
+- **`session_unset()`** — clears ALL session variables. [S1]
+- **`session_destroy()`** — destroys all data tied to the current session entirely. [S1]
+- **Default lifetime** — session data persists until the browser closes (unlike cookies, which can have a long fixed expiration). [S1]
+- **Sessions vs. cookies** — sessions: server-stored, more secure, closes-on-browser-close, more efficient (no repeated data transfer); cookies: browser-stored, less secure, long expiration possible, less efficient (sent with every request). [S1]
+
+## 📖 세부 내용 (Details)
+- Start + set variables: `session_start(); $_SESSION["favcolor"] = "green"; $_SESSION["favanimal"] = "cat";`. [S1]
+- Retrieve on another page: `session_start(); if(isset($_SESSION["favcolor"])) { echo $_SESSION["favcolor"]; }`. [S1]
+- Modify: overwrite directly — `$_SESSION["favcolor"] = "yellow";`. [S1]
+- Destroy (logout): `session_start(); session_unset(); session_destroy(); echo "You have been logged out.";`. [S1]
+- Debug all values: `print_r($_SESSION);`. [S1]
+
+## ⚖️ 모순 및 업데이트 (Contradictions & updates)
+소스에서 모순되는 정보는 발견되지 않음.
+
+## 🛠️ 적용 사례 (Applied in summary)
+현재 발견된 실제 적용 사례가 없습니다 — session_unset()+session_destroy() 조합으로 로그아웃을 구현하는 것이 실전 인증 시스템의 표준 패턴이다. [S1]
+
+## 💻 코드 패턴 (Code patterns)
+Logging out by clearing all session data (PHP):
+```php
+session_start();
+session_unset();
+session_destroy();
+echo "You have been logged out.";
+```
+
+## ✅ 검증 상태 및 신뢰도
+- **상태:** draft
+- **검증 단계:** conceptual
+- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
+- **신뢰 점수:** 0.90
+- **중복 검사 결과:** 신규 생성 (New discovery)
+
+## 🔗 지식 그래프 (Knowledge Graph)
+- **상위/루트:** [[PHP Tutorial]]
+- **관련 개념:** [[PHP Cookies]], [[PHP Filter]]
+- **참조 맥락:** 서버 측 사용자 데이터 저장 — 필터(Filter) 섹션으로 이어짐.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — PHP Sessions — https://www.w3schools.com/php/php_sessions.asp
+
+## 📝 변경 이력 (Change history)
+- 2026-07-04: Initial draft synthesized from the W3Schools "PHP Sessions" page (Astra wiki-curation, P-Reinforce v3.1 format).