The change contributed in https://github.com/sbt/sbt/pull/4130 to start sbt within VS Code looked ok at first, but when I published the extension and started using it, I realized that it's a bit broken.
Basically there's no cleanup logic (that I could find), so simply closing VS Code would leave `project/target/active.json` behind, which lets VS Code extension to attempt connection, and it fails because there's no server running. To workaround this, I'll attempt to connect to the socket to confirm sbt server is up.
In addition to TCP, this adds sbt server support for IPC (interprocess communication) using Unix domain socket and Windows named pipe.
The use of Unix domain socket has performance and security benefits.
This is the first cut for the Language Server Protocol on top of server that is still work in progress.
With this change, sbt is able to invoke `compile` task on saving files in VS Code.
Eugene Yokota