Function agl_collapse_exact 

pub fn agl_collapse_exact(n: usize) -> AglCollapse

The exact AGL collapse (n ≤ 3). Canonicalize every Bₙ-orbit representative under the full affine group in point-set space (affine_canonical_form); the number of distinct canonical forms is the exact AGL-class count. Brute over |AGL(n,2)| per orbit, so bounded to n ≤ 3.