Constant SPARSE_VALUES_GRAD 

pub const SPARSE_VALUES_GRAD: &str = "rlx_sparse.values_grad";

Outer-product gather op (the dL/dvalues building block). Computes out[k] = u[row_of(k)] * v[col_idx[k]] for each non-zero position k in the CSR pattern. Used by SparseLu/SparseMatVec/ SparseCg/SparseGmres VJPs to gather the dense outer-product u ⊗ v at the matrix’s nonzero positions.