Function proposal 

pub fn proposal(
    q: &ValidatedQuestion,
    request: DynamicRequestId,
    capability: &DynamicCapability,
    attempt_id: &str,
    answer: DynamicAnswer,
) -> DynamicProposal

A proposal for an accepted answer (3.6): always model-derived, with the request and the backend output in its lineage; the exact steps that ran are listed, never a relabeling. validate always ran; abstention is listed only when thresholds were applied, so a label accepted under the explicit label_only posture, where no abstention rule runs (AbstentionDecision::LabelOnly), lists validate alone.