  We examine Hopf cyclic cohomology in the same context as the analysis of the
geometry of loop spaces $LX$ in derived algebraic geometry and the resulting
close relationship between $S^1$-equivariant quasi-coherent sheaves on $LX$ and
$D_X$-modules. Furthermore, the Hopf setting serves as a toy case for the
categorification of Chern character theory. More precisely, this examination
naturally leads to a definition of mixed anti-Yetter-Drinfeld contramodules
which reduces to that of the usual mixed complexes for the trivial Hopf algebra
and generalizes the notion of stable anti-Yetter-Drinfeld contramodules that
have thus far served as the coefficients for Hopf-cyclic theories. The
cohomology is then obtained as a $Hom$ in this dg-category between a Chern
character object associated to an algebra and an arbitrary coefficient mixed
anti-Yetter-Drinfeld contramodule.
