Worked on the VKCOM/kphp repository to deliver the HTTP Headers Sent State API, enhancing the runtime’s ability to determine if HTTP headers have already been sent during response handling. Focused on improving the correctness and robustness of the HTTP lifecycle, the work included implementing the headers_sent API in C++ and PHP, as well as developing Python-based tests to validate behavior after flush operations and within shutdown callbacks. This approach increased runtime stability and observability, reducing the risk of header-related regressions. The contribution emphasized runtime development, system programming, and testing, supporting more reliable HTTP response management for business applications.