In January 2025, C Whu enhanced the centrapay/documentation repository by implementing idempotency for the Payment API, addressing the risk of duplicate transactions. They introduced an idempotencyKey field to the pay-a-payment request API, ensuring that repeated requests would not result in multiple charges. Using JavaScript for API development and Markdown for documentation, C Whu updated snapshot tests and created comprehensive guides to clarify idempotency behavior for integrators. Their work focused on improving reliability and developer experience, validating compatibility with existing payment flows, and providing clear technical documentation. The depth of the changes reflects a thoughtful approach to robust API design.