POS System Complete Flow Legend: Safe Improvements ✨ Online Required Offline Capable START User Type? CASHIER Cashier Login (PIN/Password) Online? NO Load Cached Data YES Sync Firebase Data SUPERVISOR Supervisor Login (Email/Password) Online? NO Redirect to POS YES Admin Dashboard 📦 Products 👥 Cashiers 📊 Reports 💰 Billing ✨ POS Interface ✨ Dynamic Categories ✨ Connection Status Indicator ✨ Stock Warnings & Auto-save Cart Select Products Browse & Add Items Add to Cart (Auto-save to IndexedDB) Checkout? NO Continue YES Payment Methods 💵 Cash 💳 Card 📱 DuitNow QR ✨ Online? NO Queue Transaction (IndexedDB) YES Save to Firebase (Real-time) Generate Receipt ✨ Unique Receipt ID ✨ Device Timestamp ✨ Void Option (5 mins) END Background Sync (Auto when online) 📤 Upload Queued Tx 🔄 Sync Products 📊 Update Reports