  We prove that the polynomials counting locally free, absolutely
indecomposable, rank 1 representations of quivers over rings of truncated power
series have non-negative coefficients. This is a generalisation to higher depth
of positivity for toric Kac polynomials. The proof goes by inductively
contracting/deleting arrows of the quiver and is inspired from a previous work
of Abdelgadir, Mellit and Rodriguez-Villegas on toric Kac polynomials. We also
relate counts of absolutely indecomposable quiver representations in higher
depth and counts of jets over fibres of quiver moment maps. This is expressed
in a plethystic identity involving generating series of these counts. In rank
1, we prove a cohomological upgrade of this identity, by computing the
compactly supported cohomology of jet spaces over preprojective stacks. This is
reminiscent of PBW isomorphisms for preprojective cohomological Hall algebras.
Finally, our plethystic identity allows us to prove two conjectures by Wyss on
the asymptotic behaviour of both counts, when depth goes to infinity.
