The grade restriction rule is an important element in specifying the category of B-branes in 2d (2,2) supersymmetric gauge theories. In this talk, I will derive the rule from convergence of the hemisphere partition function when the gauge group is semisimple and the matter representation is symmetric. The resulting category agrees with the non-commutative crepant resolution of the quotient singularity by Spenko and Van den Bergh (and its generalizations).