In this talk, we describe a categorical interpretation of Saito's theory of primitive forms using matrix factorizations. This naturally leads to a definition of $G$-equivariant Saito theory. In the case of an invertible polynomial $W$ with a diagonal special linear symmetry group $G$, we show that if the Hodge-to-de-Rham degeneration holds for the category ${\sf MF}_G(W)$, then there exists a canonical choice of categorical primitive form. Conjecturally, the resulting invariants is mirror dual to the genus zero part of the FJRW theory.