  Wall-crossing phenomena are ubiquitous in many problems of algebraic geometry
and theoretical physics. Various ways to encode the relevant information and
the need to track the changes under the variation of parameters lead to rather
complicated transformation rules and non-trivial combinatorial problems. In
this paper we propose a framework, reminiscent of collections and plethysms in
the theory of operads, that conceptualizes those transformation rules. As an
application we obtain new streamlined proofs of some existing wall-crossing
formulas as well as some new formulas related to attractor invariants.
