From NixOS/rfcs#68 (comment)

@Ericson2314 Would you be opposed to closing this RFC and creating a new feature request issue in the Nix repo? Having a minimal daemon is not really a potentially controversial or hard change that requires a shepherd team and all that :-) What do you think?

OK opening this. For me the requirements are this:

• Don't build libexpr libfetchers
• Expose modern nix-daemon and legacy nix-daemon

It seems like then we would have to make libcmd and libmain not depend on libexpr. Interesting!