Per review: (H1) exactly-two-category binding already has its meaningful-fail twin; (H2) a weighted total whose unit does not match the coefficient unit refuses missing_weighted_total (never a cross-unit sum); (H3) answer-choice ties EXACTLY or refuses no_matching_option (never nearest). All three were already handled by construction; these pin them so they stay handled.
generate/answer_choices/{parse,verify}.py: parse_options normalizes {label:value} to {label:int} (int or single-integer string; ambiguous/empty refuse). verify_answer_choice ties a PROVEN value to exactly one option -> ChoiceVerdict(consistent); a disagreeing key -> ChoiceVerdict(contradiction) naming both the consistent answer and the wrong key (truth discipline, not a refusal). Refuses no_matching_option / ambiguous_options / unknown_provided_label.
End-to-end with C2 gold + C3 solver: every solved fixture solves, ties to its labeled answer, confirms consistent. Off-serving. 9 tests incl. contradiction-flag meaningful-fail.
