def evaluate(case):
    """Return a dict with decision, reason, candidate_pair, confidence_score, confidence_band,
    contradictions, reversible_link, canonical_person_id, and unmerge_evidence.

    Derive the result only from visible synthetic evidence. Preserve ambiguity and do not authorize
    an irreversible merge from a confidence score.
    """
    raise NotImplementedError("Implement the bounded identity-linkage evidence contract")