Senior Full-Stack Engineer for System Stabilization on Replit

Introduction T&T Concept Co., Ltd. is seeking a seasoned Senior Full-Stack Engineer with expertise in Replit to stabilize a large internal operations application. The core functionalities of HR, scheduling, tasks, and permissions are in place, but we are currently in a phase where fixing one issue often leads to the emergence of another. This role focuses on system hardening and preventing regression, not on UI development or new feature creation. Deliverables Stabilize permission and scheduling logic. Fix recurring task/idempotency issues. Align development and production data. Add seed data and set up reproducible tests. Implement basic logging and audit trail. Refactor for a single source of truth where necessary. We require strong proficiency in JavaScript/TypeScript, database design, and experience in debugging complex state and refactoring. Applicants should share examples of systems they have stabilized and their approach to preventing cascading regressions.