`handshake-stream` is a tiny Node.js library that wraps any duplex stream with a preliminary two‑way handshake. It lets both peers exchange an arbitrary JSON payload, inspect the remote’s data, and explicitly accept or reject the connection before the underlying protocol (e.g., Hyperlog replication) begins. The module is aimed at developers building networked or pipe‑based protocols who need a simple way to verify version compatibility, authentication, or other pre‑conditions before streaming data.