Non-unital $C^{*}$-categories, (co)limits, crossed products and exactness

Abstract: We provide a reference for basic categorial properties of the categories of (possibly non-unital) $\mathbb{C}$-linear $$-categories or $C^{}$-categories, and (not necessarily unit-preserving) functors. Generalizing the classical case of algebras with $G$-action, we extend the construction of crossed products to categories with $G$-action. We will show that the crossed product functor preserves exact sequences and excisive squares and sends weak equivalences to equivalences.