  We prove a homological mirror symmetry equivalence between an $A$-brane
category for the pair of pants, computed as a wrapped microlocal sheaf
category, and a $B$-brane category for a mirror LG model, understood as a
category of matrix factorizations. The equivalence improves upon prior results
in two ways: it intertwines evident affine Weyl group symmetries on both sides,
and it exhibits the relation of wrapped microlocal sheaves along different
types of Lagrangian skeleta for the same hypersurface. The equivalence proceeds
through the construction of a combinatorial realization of the $A$-model via
arboreal singularities. The constructions here represent the start of a program
to generalize to higher dimensions many of the structures which have appeared
in topological approaches to Fukaya categories of surfaces.
