# AUTH-002 — Logout and Session Destruction
## Implementation Memory

Sprint    : Sprint 2 — Authentication & Authorization
Task ID   : AUTH-002
Status    : IMPLEMENTATION COMPLETE — Awaiting Human Approver review
Completed : 2026-07-05

---

## 1. Implementation Summary

AUTH-002 implements a secure POST-only logout flow for the Inveetaire platform.

The implementation:
- Adds `AuthService::performLogout()` — all session destruction business logic
- Adds `AuthController::logout()` — thin HTTP handler (no-cache headers + delegate + redirect)
- Registers `POST /logout` with `CsrfMiddleware` in `app/modules/Auth/routes.php`
- No new files created — exactly as specified by AUTH-002 (Files Expected: None)
- Sprint 0 kernel unchanged. No app/core/ file modified.

Logout flow sequence:
1. CsrfMiddleware validates POST token (rejects invalid/absent tokens with 403)
2. AuthController::logout() emits no-cache HTTP headers
3. AuthService::performLogout() captures user_id + role for audit log
4. Session::destroy() clears $_SESSION, expires cookie, destroys server session file
5. session_start() opens a clean anonymous session (needed to persist flash message)
6. Session::regenerate(false) gives browser a fresh unfixated session cookie
7. Flash success message written to $_SESSION['flash']['success']
8. Logger::info() records logout event (user_id, role, IP — no credentials)
9. AuthController::redirect('/login') sends 302

---

## 2. Files Created

None. AUTH-002 specification: "Files Expected: None (uses Auth Controller & Service)"

---

## 3. Files Modified

| File | Change |
|------|--------|
| `app/modules/Auth/AuthController.php` | Added `logout()` action method; updated class docblock |
| `app/modules/Auth/AuthService.php` | Added `performLogout()` method; updated class docblock |
| `app/modules/Auth/routes.php` | Added `POST /logout` route with CsrfMiddleware; updated docblock |

---

## 4. Key Design Decisions

### session_start() after Session::destroy()
After Session::destroy() the PHP session is gone. A plain `$_SESSION['flash']` write
would fail silently. The implementation calls `session_start()` to open a new anonymous
session before writing the flash message. This is the only way to persist the flash
message across the redirect to /login without modifying the Session core class (which
is frozen).

### Session::regenerate(false) on the new session
After session_start() opens a fresh session, regenerate(false) is called with
deleteOld=false because there is no old server-side session file to delete
(Session::destroy() already removed it). This gives the browser a brand-new
unfixated session cookie immediately.

### No-cache HTTP headers in Controller
The Cache-Control/Pragma/Expires headers are emitted in the Controller (not the
Service) because they are HTTP transport concerns, not business logic. The Service
remains responsible for session state only.

### CSRF protection on POST /logout
POST /logout is registered with CsrfMiddleware in routes.php. Any GET request to
/logout returns 404 (no GET route registered). Any POST without a valid CSRF token
returns 403 (CsrfMiddleware rejects it before the controller executes).

---

## 5. Syntax Validation

| File | Result |
|------|--------|
| `app/modules/Auth/AuthController.php` | ✅ No syntax errors detected |
| `app/modules/Auth/AuthService.php` | ✅ No syntax errors detected |
| `app/modules/Auth/routes.php` | ✅ No syntax errors detected |

Validated using: `C:\xampp\php\php.exe -l`

---

## 6. Dependency State at Implementation

| Dependency | Status |
|------------|--------|
| AUTH-001 committed (commit 50e9b19) | ✅ |
| AUTH-001 pushed (branch: main, up to date with origin/main) | ✅ |
| Working tree clean (only AUTH-002 modified files in diff) | ✅ |
| Sprint 0 kernel unchanged (no app/core/ file modified) | ✅ |
| Sprint 1 utilities unchanged (no helpers, CsrfMiddleware untouched) | ✅ |
| Session::destroy() exists in app/core/Session.php | ✅ |
| Session::regenerate() exists in app/core/Session.php | ✅ |
| FlashMessage pull semantics — BaseController::flash() exists | ✅ |
| CsrfMiddleware exists at app/middleware/CsrfMiddleware.php | ✅ |

---

## 7. Documentation Deviations

None. AUTH-002 implemented exactly as specified in:
- MASTER_IMPLEMENTATION_BACKLOG_v1.1.md §AUTH-002
- SPRINT2_PLANNING.md §5 AUTH-002
- SPRINT2_EXECUTION_GUIDE.md §2.2

The previously approved view-path deviation from AUTH-001 does not affect AUTH-002
(AUTH-002 creates no views).

AUTH-002 is complete. Awaiting Human Approver review before AUTH-003 begins.