Secure Back-End Engineer - Sports Betting & Prediction Market Engine

# SECURE BACK-END ENGINEER - SPORTS BETTING & PREDICTION MARKET ENGINE ## Project Overview We are launching Luckybet, an exclusive, invite-only digital sports betting and social prediction platform (similar to Polymarket). The platform operates via trusted local agents (cashiers) who manage physical cash top-ups. Security, speed, and strict financial transaction ledger rules are the absolute backbone of our operation. ## Project Scope We are seeking an expert, security-focused Back-end Developer to design and develop the core engine of Luckybet. You will be responsible for creating a secure transactional ledger, setting up database architectures with strict transactional guarantees, integrating real-time sports odds APIs, and building secure REST APIs for clients, agents, and administrators. (Note: You will be collaborating closely with our Front-End developer, who will build the responsive UI using Tailwind CSS). ## Key Responsibilities * Secure Transactional Ledger: Build a bulletproof balance system for Users and Agents. All balance updates must execute within strict database transactions (ACID compliant) to prevent double-spending, race conditions, or balance leaks. * Agent (Cajero) Commission Engine: Program the automated commission ledger. Every time an agent credits a client's balance, a 3% commission must instantly be calculated and accrued to the agent's wallet. Block transactions if the agent's pre-paid balance is insufficient. * Risk Management and Core Betting Rules: Implement server-side validation to enforce safety limits: strict maximum bet caps per ticket, maximum payout limits per ticket, and custom caps for prediction markets. * Third-Party API Integration: Integrate a reliable, real-time sports odds feed API to fetch matches, display live odds, and settle game outcomes automatically. * Prediction Market Manager: Build CRUD and state machine engines for customized Polymarket-style binary markets (political events, social trends) manageable by the Admin. * Authentication & Authorization: Establish a secure JWT-based auth system for three clear roles: Admin, Agent, and Client, using a 4-digit PIN system for fast client mobile access. ## Technical Stack Required * Node.js (TypeScript / Express / NestJS) OR Python (FastAPI / Django). * PostgreSQL or MySQL (Highly structured relational schema with strict transaction constraints is mandatory). * Redis (for caching odds and session controls). * WebSockets or Server-Sent Events (SSE) for real-time odds and balance updates. * High security awareness (protection against SQL injection, secure environment variables, hashed credentials).