velvet-inventory

byTest

Build a complete mobile-first POS + Inventory + QR Label + Serial Tracking system using Expo (React Native). The app must be fully functional, offline-first, and production-ready with real logic (no placeholders). ==================================================== SYSTEM OVERVIEW ==================================================== This system manages SERIAL-LEVEL inventory with QR-based tracking. Each unit is uniquely tracked using a globally continuous serial number. Full flow: QR Label → Purchase (Stock In) → Inventory → Sales → Invoice → Transactions → Reports ==================================================== DATABASE DESIGN (STRICT) ==================================================== products: id name sku (unique) price created_at purchases: id created_at purchase_items: id purchase_id product_id serial_number (UNIQUE GLOBAL) batch price status (AVAILABLE / SOLD) created_at sales: id invoice_number (AUTO GENERATED, UNIQUE) created_at sales_items: id sale_id purchase_item_id price created_at business_details: id name phone address gst logo (image path/base64) signature (image path/base64) qr_settings: id same_fields (boolean) label_fields (JSON) qr_fields (JSON) IMPORTANT RULES: - Inventory is SERIAL-BASED - DO NOT store quantity in products - Quantity = COUNT(purchase_items WHERE status='AVAILABLE') - Serial number must be globally continuous (SN00001, SN00002… no reset per product) - One purchase = one bill - One sale = one bill ==================================================== 1. INVENTORY MODULE (STOCK TAB) ==================================================== - Add / edit / delete products - Auto-create product if not exists during scan or QR generation - SKU: - Auto or manual - Reuse if product exists - Show: - Total products - Available stock (count AVAILABLE serials) - Sold stock - Product detail: - List of serials (available + sold) ---------------------------------------------------- SCAN TO ADD STOCK ---------------------------------------------------- - Scan QR - If product does not exist → AUTO CREATE - Insert new purchase_item - Assign next global serial number ==================================================== 2. PURCHASE SYSTEM (GROUPED BILL) ==================================================== - One purchase = one bill - Multiple products inside Example: Biscuit (5) Honey (10) System must: → create 15 purchase_items → all under ONE purchase_id Each unit: - serial_number - batch - price ==================================================== 3. QR LABEL GENERATOR (CORE FEATURE) ==================================================== MULTI-PRODUCT INPUT: User can add multiple products in one batch: Example: Biscuit (5) Honey (10) FIELDS: - product_name - sku (auto/manual) - price - batch - starting_serial (optional) - quantity ---------------------------------------------------- SERIAL NUMBER LOGIC ---------------------------------------------------- - Format: SN00001, SN00002... - MUST be globally continuous across ALL products - Example: Biscuit 5 → SN00001–SN00005 Honey 10 → SN00006–SN00015 ---------------------------------------------------- QR DATA FORMAT (DYNAMIC JSON) ---------------------------------------------------- Example: { product_name, sku, price, batch, serial_number } Fields must be dynamically controlled by settings ---------------------------------------------------- LABEL DESIGN ---------------------------------------------------- Each label contains: - QR code - Selected text fields (dynamic) ---------------------------------------------------- A4 PDF GENERATION ---------------------------------------------------- - Grid layout (e.g., 24 labels/page) - Fill left → right → top → bottom - Combine multiple products in same pages - No empty spaces - Multi-page support ---------------------------------------------------- PREVIEW ---------------------------------------------------- - Show total labels - Show total pages ---------------------------------------------------- INVENTORY INTEGRATION ---------------------------------------------------- Toggle: [✓] Add to Inventory If enabled: → Create ONE purchase → Insert ALL units into purchase_items ==================================================== 4. SALES MODULE (CORE ENGINE) ==================================================== - Create ONE sale (bill) - Add items via: - QR scan (auto add) - Manual serial entry ---------------------------------------------------- SCAN FLOW ---------------------------------------------------- - Scan QR → extract serial_number - Find purchase_item IF: - AVAILABLE → add to cart - SOLD → show error ---------------------------------------------------- CART SYSTEM ---------------------------------------------------- - Each item = 1 serial - No quantity field ---------------------------------------------------- CHECKOUT ---------------------------------------------------- - Create ONE sale - Generate invoice_number automatically (e.g., INV-0001) - Insert multiple sales_items - Update: purchase_items.status = SOLD ---------------------------------------------------- IMPORTANT ---------------------------------------------------- - Invoice must be auto-created and saved silently - DO NOT show popup to generate invoice ==================================================== 5. INVOICE SYSTEM ==================================================== - Invoice is auto-created at checkout - Stored in system ---------------------------------------------------- ACCESS INVOICE ---------------------------------------------------- - Only accessible from Transactions tab ---------------------------------------------------- INVOICE DESIGN ---------------------------------------------------- Professional PDF: - Business logo - Business details - Customer placeholder (optional) - Product list - Serial numbers - Price per unit - Total amount - Invoice number - Date - Signature / stamp ==================================================== 6. TRANSACTIONS TAB (SALES LOG) ==================================================== - Unified system: - Sales - Purchases ---------------------------------------------------- FEATURES ---------------------------------------------------- - Filter: - Date range - Type (sale/purchase) - Search: - Invoice number - Product - Serial number ---------------------------------------------------- SCAN TO FIND SALE ---------------------------------------------------- - Scan QR - Show: - Product details - Purchase info - Sale invoice (if sold) ---------------------------------------------------- EXPORT ---------------------------------------------------- - Export Sales PDF - Export Purchase PDF - Based on selected date range ==================================================== 7. DASHBOARD (HOME TAB) ==================================================== Show: - Total sales amount - Total transactions - Total products - Available stock - Sold items - Recent sales preview ==================================================== 8. SETTINGS TAB ==================================================== ----------------------------------- 1. BUSINESS INFORMATION ----------------------------------- - Name - Phone - Address - GST - Upload: - Logo - Signature / Stamp ----------------------------------- 2. DATA MANAGEMENT ----------------------------------- - Export full database (JSON) - Import JSON backup - Reset data (optional) ----------------------------------- 3. QR CODE GENERATE SETTINGS ----------------------------------- FIELD TOGGLES: [✓] Product Name (required) [✓] SKU [✓] Price [✓] Batch [✓] Serial Number [ ] Variant [ ] MFG Date [ ] EXP Date ----------------------------------- MODE: ----------------------------------- (•) Same fields for Label & QR ( ) Separate configuration If separate: - Label fields - QR fields ----------------------------------- BEHAVIOR: ----------------------------------- - QR generator must read settings - Only selected fields: → encoded in QR → printed on label - Settings must persist ==================================================== TECH REQUIREMENTS ==================================================== - Expo (React Native) - expo-sqlite (database) - expo-camera (QR scanner) - expo-print (PDF) - expo-sharing - expo-file-system UI: - Bottom Tabs: Home | Sales | Stock | Sales Log | Settings - Mobile-first design - Fast scanning experience ==================================================== OUTPUT REQUIREMENTS ==================================================== - Full folder structure - All screens implemented - Database setup - Fully working logic (NOT pseudo code) - Ready to run in Expo ==================================================== STRICT RULES ==================================================== - Do NOT skip any module - Do NOT store quantity directly - Do NOT break serial sequence - Do NOT hardcode QR fields - Maintain full data consistency - Ensure complete flow from QR → Sale → Invoice → Report