Code review of a project I worked on

The startup I had been working in throughout late 2025 to 2026 has ceased operations. During the year of my tenure, my role involved building the infrastructure for communicating with a proprietary service, with minimal assistance from my other colleages. The projects I built include a TCP client library and a gateway for routing messages to and between a fleet of clients, as well as others I won't be writing about. I believe some of my successes and failures are valuable and worth retelling.