Hi, with great help from the upstream author, the cyclic build dependency has been solved now. However, I still only intend to package the topkg packaging library and not the topkg-care tool, because the latter has a number of build dependencies that are not (yet) available in Debian.
I intend to name the source package ocaml-topkg with binary packages libtopkg-ocaml and libtopkg-ocaml-dev, if needed. Regards, Hendrik