Function affine_reduce 

pub fn affine_reduce(truth: &[bool]) -> Option<AffineReduction>

Peel a linear form off a Boolean function so its complement linear structures become invariances, then reduce. Catches f = h ⊕ ℓ where ℓ is linear and h collapses — the residue-plus-a-linear-form class every other axis misses. Fail-closed: returns Some only if the reconstruction re-checks exactly. None when there are no complement structures (pure invariance is reduce_by_invariance’s job).