Expert MERN Stack Developer Needed to Restructure Booking System Pricing Engine

We are seeking a senior MERN stack developer to audit, refactor, and permanently fix the pricing engine of our custom booking system. Currently, the system is experiencing a series of calculation errors under varying conditions. We need a robust, scalable architectural fix to ensure our dynamic pricing functions flawlessly across all booking scenarios. The Problem: Our dynamic pricing logic handles complex, conditional rules that our current architecture is failing to calculate consistently. For example, the engine must flawlessly execute occupant-based promotional logic. As rules stack and dates change, the current engine breaks down, leading to persistent calculation errors. We need to move away from band-aid fixes and restructure the engine for absolute mathematical accuracy. Audit & Diagnose: Review the existing Express/Node.js pricing logic to identify the root causes of the calculation errors and architectural bottlenecks. Restructure & Refactor: Redesign the pricing engine to cleanly handle dynamic variables (base rates, guest counts, tiered discounts, date-based fluctuations, and promotional codes). Database Optimization: Ensure the MongoDB schemas supporting the pricing structure are optimized for these complex calculations without performance degradation. Testing & Validation: Write comprehensive unit and integration tests (using Jest or similar) for every possible pricing edge case to guarantee the engine calculates to the exact cent before deployment. Deliverables: A detailed brief on what is currently causing the errors. A fully refactored, cleanly written Node.js/Express pricing module. A complete suite of unit tests verifying all dynamic pricing rules and edge cases.