Function answers_agree 

pub fn answers_agree(
    f_a: Number,
    f_b: Number,
    slack: Number,
    gap: Number,
) -> bool

Do two answers agree, within same_answer_allowance? slack is the sum of the two points’ relaxation_slacks and gap of their complementarity_gaps. The exact stage’s cold G·H = 0 solve is skipped when the continuation’s answer and the exact stage’s relaxed path agree: two different routes landing on one point is evidence the cheap paths found the branch, and the cold solve – degenerate, often max_iter-bound, the largest single cost on MacMPEC – exists for the models where they do not (water-net, dempe). A slack or gap that is not finite never agrees, so the cold solve runs.