[throwanem]

Communication between urbits appears to be well defined, although my lack of close familiarity with the codebase makes it impossible for me to point at precisely where; ask someone at Tlon, or someone in Urbit :talk. Communication between an urbit and its host is precisely defined by the u3 implementation.

The C standard library lacked a formal specification for over a decade after its creation. Lisp lacked one for almost thirty years. At least one of these should be an argument in favor of "build it first, formalize it later".