During January 2025, Koji contributed to the VKCOM/kphp repository by developing the HTTP Headers Sent State API, which enables the kphp runtime to determine if HTTP headers have already been sent during response handling. Koji implemented this feature using C++ and PHP, focusing on runtime development and system programming to improve the correctness and observability of the HTTP lifecycle. To ensure reliability, Koji added Python-based tests that validated the new API’s behavior after flush operations and within shutdown callbacks. This work enhanced the robustness of HTTP response handling, reducing the risk of header-related regressions and supporting business reliability.