Worked on improving the reliability of BBR-based congestion control in the microsoft/msquic repository by addressing a bug in MinRtt validity handling. Focused on ensuring that round-trip time estimates are only used when valid, the developer updated the code to consistently rely on the MinRttTimestampValid state, preventing invalid values from impacting congestion window and pacing calculations. Enhanced unit tests to cover edge cases around MinRtt and network startup, ensuring BBR remains in STARTUP until a valid sample is established. Utilized C and C++ for code changes, applying network programming and congestion control expertise to improve stability and throughput predictability.