  We give a conjectural but full and explicit description of the (K-theoretic)
equivariant vertex for Pandharipande--Thomas stable pairs on toric Calabi--Yau
4-folds, by identifying torus-fixed loci as certain quiver Grassmannians and
prescribing a canonical half of the tangent-obstruction theory. For any number
of non-trivial legs, the DT/PT vertex correspondence can then be verified by
computer in low degrees.
