Worked on the dart-lang/sdk repository to enhance the safety and reliability of network I/O in the Dart VM. Focused on the SynchronousSocket_WriteList function, implementing range validation for its arguments to prevent out-of-bounds access and introducing robust error handling. Developed and integrated a unit test to ensure correct behavior under various input conditions, thereby reducing potential crash surfaces in synchronous socket write operations. Utilized C++ and Dart, applying skills in socket programming, error handling, and unit testing. This targeted bug fix improved runtime stability for socket operations, reflecting a careful and methodical approach to strengthening core IO infrastructure.