  The JSJ decomposition encodes the automorphisms and the virtually cyclic
splittings of a hyperbolic group. For general finitely presented groups, the
JSJ decomposition encodes only their splittings.
  In this sequence of papers we study the automorphisms of a hierarchically
hyperbolic group that satisfies some weak acylindricity conditions. To study
these automorphisms we construct an object that can be viewed as a higher rank
JSJ decomposition.
  In the first paper we demonstrate our construction in the case of a right
angled Artin group. For studying automorphisms of a general HHG we construct
what we view as a higher rank Makanin-Razborov diagram, which is the first step
in the construction of the higher rank JSJ.
