Helped develop SAP and A2R fulfillment services handling XML/CSV generation, FTP/SFTP file transmission, response parsing, and end-to-end order status reconciliation for book and journal fulfillment pipelines.
Helped develop shared libraries (mantle-helpers) providing JWT authentication strategies, structured Pino logging, SQS client wrappers, and custom error classes consumed by all services.
Created custom MCP servers and AI agent tooling to encode 4,000+ SAP/A2R business rules into machine-readable context, enabling AI-assisted development across the platform (for learning and exploring more on MCP servers).
Containerized my own local development environment with Docker Compose (MySQL, Redis, NATS, LocalStack, Traefik, Zipkin), supporting parallel legacy and refactored service operation with distributed tracing.
Maintained and enhanced a full-stack Daily Time Record (DTR) system built on Express.js 4.x, AngularJS 1.4, and MongoDB, covering 11 API route modules (DTR management, scheduling, shifts, holidays, employees, teams, reports, biometric integration) serving as the company's production attendance and payroll pipeline.
Helped develop and debug a 3,000+ line time calculation engine handling late duration, undertime, overtime, night differential, and LWOP computations, with edge-case handling for midnight-crossing shifts, half-day leaves, rest day exemptions, and employee-level exemption flags.
Helped develop ADP payroll report generation using ExcelJS, producing 37-column Excel exports aggregating 8 day types (ordinary, rest day, holiday variants) with overtime multipliers, night differential hours, and running leave balance calculations across monthly periods.
Helped develop AWS Lambda and SQS infrastructure (SAM-deployed, Node.js 20.x) for real-time RFID biometric time recording, consuming tap events from SQS queues with dead-letter queue failover and VPC-restricted network access to the DTR API.
Helped develop a serverless Space Reservation System (SRS) across 3 repositories using AWS SAM, Lambda (Node.js 20.x), MSSQL with Sequelize ORM, and Firebase for authentication and push notifications, covering resource bookings, parking management, workstation assignment, and building administration.
Helped develop batch operation scripts for employee data migrations, holiday calendar loading, leave balance backfills, and cost center assignments, using direct MongoDB operations with shared computation libraries for DTR recalculations.
Helped enforce code quality with Jest (90% line coverage threshold on critical calculation paths), ESLint, Prettier, and structured Pino logging, with separate lint targets for AngularJS frontend and Express backend codebases.
