///|
/// Immutable relay-identity bundle. Built once in `main` after the
/// token is acquired and the uuid + hostname + cwd are known. Every
/// function that talks to the relay threads this through instead of
/// five separate params.
struct ConnectConfig {
  url : @url.Url
  headers : Map[String, String]
  task_uuid : @uuid.UUID
  hostname : String
  cwd : String
}