diff --git a/docs/COMPLETED.md b/docs/COMPLETED.md
index ddbd0a2..b1fc987 100644
--- a/docs/COMPLETED.md
+++ b/docs/COMPLETED.md
@@ -99,6 +99,58 @@
 
 ---
 
+## ✅ Phase 1.5 Continuation: QR Code Check-in System (COMPLETED)
+
+**Completed:** 2025-11-14
+**Time Spent:** ~4 hours
+**Status:** Production-ready with security fixes
+
+### QR Code Event Check-in Implementation
+- [x] Database schema extension:
+  - EventCheckinToken model (id, event_id unique, token cuid unique, created_at)
+  - Migration: `20251114125544_add_event_checkin_tokens`
+  - One token per event (on-demand generation)
+- [x] Backend endpoints:
+  - `GET /api/events/:slug/details` - Get event details with QR code token and participants
+  - `POST /api/events/checkin/:token` - Check-in to event via QR code scan
+  - `DELETE /api/events/:slug/leave` - Leave event (remove participation)
+  - Date validation (startDate - 1 day to endDate + 1 day, disabled in dev mode)
+  - Participant count updates (increment/decrement)
+- [x] Frontend pages:
+  - EventDetailsPage.jsx - QR code display (qrcode.react), participant list, stats
+  - EventCheckinPage.jsx - Check-in confirmation screen with event info
+  - EventChatPage.jsx - Access control (verify participation before showing chat)
+  - EventsPage.jsx - Check-in requirement notice, dev-only details link
+- [x] Security implementation:
+  - Frontend access control (check participation status)
+  - Socket.IO handler verification (prevent auto-participation)
+  - Dev-only QR code access (import.meta.env.DEV)
+  - Leave Event button with confirmation modal
+- [x] UX improvements:
+  - Real participant counts using `_count.participants`
+  - Joined events shown first in events list
+  - Check-in required screen for non-participants
+  - Dev mode shortcuts for testing
+- [x] Security fixes:
+  - Fixed bypass vulnerability (page refresh granting unauthorized access)
+  - Removed auto-participation from Socket.IO handler
+  - Added participant verification before room join
+
+### Git Commits (QR Code Check-in)
+1. `feat: add QR code event check-in system`
+2. `fix: improve event check-in UX and participant counting`
+3. `fix: prevent bypassing event check-in via page refresh`
+
+### Key Features
+- Physical presence requirement (QR code must be scanned at venue)
+- On-demand token generation (created when admin views /details)
+- Development mode bypass for date validation
+- Secure token generation (CUID)
+- Complete access control (frontend + backend + socket)
+- Leave event functionality with confirmation
+
+---
+
 ## 🐳 1. Setup projektu i infrastruktura
 
 ### Docker Compose
@@ -309,5 +361,5 @@ docs: update TODO.md with completed tasks and next steps
 
 ---
 
-**Last Updated:** 2025-11-12
+**Last Updated:** 2025-11-14
 **Note:** This file is an archive. For current tasks, see TODO.md
diff --git a/docs/SESSION_CONTEXT.md b/docs/SESSION_CONTEXT.md
index 88b510e..0d76177 100644
--- a/docs/SESSION_CONTEXT.md
+++ b/docs/SESSION_CONTEXT.md
@@ -23,7 +23,7 @@
 - ✅ Docker Compose (nginx:8080 + frontend + backend + PostgreSQL)
 - ✅ All frontend views with real API integration
 - ✅ Backend API (Node.js + Express)
-- ✅ PostgreSQL database with 7 tables (Prisma ORM)
+- ✅ PostgreSQL database with 8 tables (Prisma ORM)
 - ✅ Real authentication (JWT + bcrypt)
 - ✅ **Email verification (AWS SES with link + PIN code) - Phase 1.5**
 - ✅ **Password reset workflow - Phase 1.5**
@@ -32,6 +32,7 @@
 - ✅ **Public profiles (/{username}) - Phase 1.5**
 - ✅ **Event participation tracking - Phase 1.5**
 - ✅ **Event security (unique slugs, no ID enumeration) - Phase 1.5**
+- ✅ **QR code event check-in system - Phase 1.5** (requires physical presence at venue)
 - ✅ Real-time chat (Socket.IO for event & match rooms)
 - ✅ WebRTC P2P transfer UI mockup
 
@@ -113,13 +114,15 @@
 - `frontend/src/pages/ResetPasswordPage.jsx` - Reset password with token
 - `frontend/src/pages/ProfilePage.jsx` - **UPDATED: Edit profile (social media, location) - Phase 1.5**
 - `frontend/src/pages/PublicProfilePage.jsx` - **NEW: View other user profiles - Phase 1.5**
-- `frontend/src/pages/EventsPage.jsx` - **UPDATED: Real API, joined events first - Phase 1.5**
-- `frontend/src/pages/EventChatPage.jsx` - **UPDATED: Uses slugs instead of IDs - Phase 1.5**
+- `frontend/src/pages/EventsPage.jsx` - **UPDATED: Shows check-in requirement, dev-only QR access - Phase 1.5**
+- `frontend/src/pages/EventChatPage.jsx` - **UPDATED: Access control with check-in verification, Leave Event - Phase 1.5**
+- `frontend/src/pages/EventDetailsPage.jsx` - **NEW: QR code display, participant list - Phase 1.5**
+- `frontend/src/pages/EventCheckinPage.jsx` - **NEW: Check-in confirmation page - Phase 1.5**
 - `frontend/src/pages/MatchChatPage.jsx` - Private chat + WebRTC mockup
 - `frontend/src/components/common/PasswordStrengthIndicator.jsx` - Password strength indicator
 - `frontend/src/components/common/VerificationBanner.jsx` - Email verification banner
 - `frontend/src/contexts/AuthContext.jsx` - JWT authentication integration
-- `frontend/src/services/api.js` - **UPDATED: eventsAPI uses slugs - Phase 1.5**
+- `frontend/src/services/api.js` - **UPDATED: QR check-in methods (checkin, getDetails, leave) - Phase 1.5**
 - `frontend/src/services/socket.js` - Socket.IO client connection manager
 - `frontend/src/data/countries.js` - **NEW: List of 195 countries - Phase 1.5**
 
@@ -127,17 +130,18 @@
 - `backend/src/controllers/auth.js` - Register, login, email verification, password reset
 - `backend/src/controllers/user.js` - **UPDATED: Profile updates (social, location) - Phase 1.5**
 - `backend/src/controllers/wsdc.js` - WSDC API proxy for dancer lookup
-- `backend/src/routes/events.js` - **UPDATED: Uses slugs instead of IDs - Phase 1.5**
+- `backend/src/routes/events.js` - **UPDATED: QR check-in endpoints (checkin, details, leave), participant verification - Phase 1.5**
 - `backend/src/routes/users.js` - **UPDATED: Public profile endpoint - Phase 1.5**
-- `backend/src/socket/index.js` - **UPDATED: Slug-based event rooms, participation tracking - Phase 1.5**
+- `backend/src/socket/index.js` - **UPDATED: Participant verification before room join, security fix - Phase 1.5**
 - `backend/src/utils/email.js` - AWS SES email service with HTML templates
 - `backend/src/utils/auth.js` - Token generation utilities
 - `backend/src/middleware/auth.js` - Email verification middleware
 - `backend/src/middleware/validators.js` - **UPDATED: Social media URL validation - Phase 1.5**
 - `backend/src/server.js` - Express server with Socket.IO integration
-- `backend/prisma/schema.prisma` - **UPDATED: 7 tables (social, location, event_participants, slugs) - Phase 1.5**
+- `backend/prisma/schema.prisma` - **UPDATED: 8 tables (EventCheckinToken added) - Phase 1.5**
 - `backend/prisma/migrations/20251113151534_add_wsdc_and_email_verification/` - Phase 1.5 migration
 - `backend/prisma/migrations/20251113202500_add_event_slug/` - **NEW: Event slugs migration - Phase 1.5**
+- `backend/prisma/migrations/20251114125544_add_event_checkin_tokens/` - **NEW: QR check-in tokens - Phase 1.5**
 
 **Config:**
 - `docker-compose.yml` - nginx, frontend, backend, PostgreSQL
@@ -148,7 +152,7 @@
 
 ## Database Schema (Implemented - Prisma)
 
-7 tables with relations:
+8 tables with relations:
 - `users` - **EXTENDED in Phase 1.5:**
   - Base: id, username, email, password_hash, avatar, created_at, updated_at
   - **WSDC:** first_name, last_name, wsdc_id
@@ -158,6 +162,7 @@
   - **Location:** country, city
 - `events` - id, **slug (unique)**, name, location, start_date, end_date, description, worldsdc_id, participants_count
 - `event_participants` - **NEW in Phase 1.5:** id, user_id, event_id, joined_at (many-to-many)
+- `event_checkin_tokens` - **NEW in Phase 1.5:** id, event_id (unique), token (cuid, unique), created_at
 - `chat_rooms` - id, event_id, match_id, type (event/private), created_at
 - `messages` - id, room_id, user_id, content, type, created_at
 - `matches` - id, user1_id, user2_id, event_id, room_id, status, created_at
@@ -167,6 +172,7 @@
 - `20251112205214_init` - Initial schema
 - `20251113151534_add_wsdc_and_email_verification` - Phase 1.5 (email, WSDC, social, location)
 - `20251113202500_add_event_slug` - **Phase 1.5 (event security - unique slugs)**
+- `20251114125544_add_event_checkin_tokens` - **Phase 1.5 (QR code check-in system)**
 
 **Seed data:** 3 events, 2 users, event chat rooms
 
@@ -314,8 +320,10 @@ RUN apk add --no-cache openssl
 - `/reset-password/:token` - Reset password with token
 - `/profile` - Edit user profile (social media, location)
 - `/:username` - Public profile view
-- `/events` - Event list (joined events first)
-- `/events/:slug/chat` - Event chat (public, real-time Socket.IO)
+- `/events` - Event list (joined events first, check-in requirement notice)
+- `/events/:slug/chat` - Event chat (requires check-in, real-time Socket.IO)
+- `/events/:slug/details` - **NEW:** Event details with QR code, participant list
+- `/events/checkin/:token` - **NEW:** QR code check-in confirmation page
 - `/matches/:id/chat` - Private 1:1 chat + WebRTC mockup
 - `/matches/:id/rate` - Rate partner
 - `/history` - Match history
@@ -354,7 +362,7 @@ RUN apk add --no-cache openssl
 
 ---
 
-**Last Updated:** 2025-11-13
+**Last Updated:** 2025-11-14
 **Phase 1 Status:** ✅ COMPLETED - Backend Foundation (Express + PostgreSQL + JWT + Socket.IO)
 **Phase 1.5 Status:** ✅ COMPLETED - Email Verification & WSDC Integration & User Profiles & Security
   - AWS SES email verification (link + PIN)
@@ -364,4 +372,5 @@ RUN apk add --no-cache openssl
   - Public profiles (/{username})
   - Event participation tracking
   - Event security (unique slugs, no ID enumeration)
+  - **QR code event check-in system** (physical presence required, dev mode bypass)
 **Next Phase:** Phase 2 - Core Features (Matches API + Ratings + WebRTC)
diff --git a/docs/TODO.md b/docs/TODO.md
index 96c0760..50de501 100644
--- a/docs/TODO.md
+++ b/docs/TODO.md
@@ -26,6 +26,7 @@
   - Public profiles (/{username})
   - Event participation tracking (auto-save joined events)
   - Event security (unique slugs, prevent ID enumeration)
+  - **QR code event check-in system** (physical presence required at venue)
 
 ### ⏳ Next Priority
 **Core Features** - Matches API + Ratings + WebRTC Signaling
@@ -256,4 +257,4 @@ git commit -m "feat: description"
 
 ---
 
-**Last Updated:** 2025-11-13
+**Last Updated:** 2025-11-14