The topological Breuil-Mézard conjecture for classical groups

For unitary, orthogonal and symplectic groups, we compute the dimension of the reduced Emerton-Gee stacks, and give an explicit description of their top-dimensional Chow group. Our results are unconditional when $p\mathrm{\ne }2$. The main innovation is a new method for analyzing the vanishing locus of Galois cup products valued in high dimensions.