Function default_socket_path 

pub fn default_socket_path() -> PathBuf

Where the CLI and the server meet: $ISB_SERVE_SOCKET, else $XDG_RUNTIME_DIR/isb/serve.sock, else a per-uid directory under /tmp. On macOS, where the daemon runs inside the isb machine, it is that machine’s forwarded socket, ~/.isb/machine/isb/serve.sock.