Jagdip Singh enhanced the DEFRA/epr-calculator-frontend and epr-calculator-service repositories by addressing both stability and feature requirements. He resolved a session management bug in the billing instruction flow, ensuring session data is only cleared after a successful API call, which prevents data loss and improves state robustness. On the backend, he developed a calendar-year conversion feature for organization pipelines, integrating it into CalculatorRunService with conditional logic and comprehensive unit tests for various input scenarios. Working primarily in C# and focusing on API integration and backend development, Jagdip’s contributions improved reliability, data integrity, and readiness for organization-level deployments within one month.