To close this thread (for you, Gentle Reader, who have stumbled upon it since ...) a type-coercion did, indeed, solve the problem perfectly.   The “magick,” that I indeed had overlooked, is that the mere mention of a coerce rule is not by itself sufficient to actually cause that coercion rule to be invoked.   (Documented, yes.   “Counter-intuitive, perhaps,” also very-definitely yes.)   I am indeed sincerely grateful and appreciative for the help ... momentarily embarrassing :*) though it turned out to be.