Shalom POS — ERP & Retail Billing System

Commercial printing, signage, and custom picture-framing businesses operate under dynamic geometric constraints that standard retail POS systems (like Shopify or Square) fail to handle: • Dynamic Area & Tiered Pricing: Jobs are not fixed-price SKUs; they require real-time two-dimensional calculations (width × height across feet, inches, centimeters) coupled with material waste multipliers, board mounts, lamination, and framing border add-ons. • Cash Register Drawer Accountability: High volumes of walk-in cash payments led to daily register balance discrepancies, missing opening float records, and unmonitored mid-shift cash withdrawals. • Post-Dated Cheque Vulnerability: The business frequently deals with post-dated customer cheques and issues post-dated supplier cheques. Without a structured maturity calendar, bounced cheques and cash-flow blind spots were frequent. • Thermal Receipt Hardware Limits: Legacy receipt drivers failed to produce readable printouts for custom dimensions and multi-line service breakdown on 80mm ESC/POS thermal printers.

• Dynamic Dimension Calculation Engine: Developed a mathematical pricing engine in TypeScript that dynamically resolves unit conversions (sq.ft, sq.in, cm, linear feet), applies configurable service tier rules, and calculates nested material add-ons with zero floating-point drift. • Strict Register Session Enforcement: Implemented an ACID-compliant cash session state machine. Cashiers are strictly prevented from billing sales unless a shift register is opened with a verified float. Automated closing reconciliation audits counted cash against expected cash and logs variance discrepancies. • Dual-Ledger Cheque Maturity Tracker: Architected a full cheque lifecycle engine distinguishing between Payable (supplier commitments) and Receivable (customer deposits) cheques, with 7-day maturity countdowns, overdue alerting, and clearance state mutations. • Pure ESC/POS Thermal Printing Pipeline: Engineered print-specific CSS (@media print) with Space Mono typography, enforcing pure black density (#000000), dashed cutlines, and sub-second print dialog rendering on 80mm thermal receipt rolls. • Strict Role-Based Access Control (RBAC) & Immutable Audit Trail: Built stateless JWT authorization with role segregation (SUPER_ADMIN, SHOP_ADMIN, CASHIER_WORKER). Implemented a comprehensive audit logging engine recording actor ID, client IP, before/after JSON diffs, and reasons for all sensitive actions (refunds, voids, price overrides, cheque clearances).