Function widen_with 

pub fn widen_with(
    replay: &GrowthReplay,
    policy: &SpacePolicy,
    space: SpaceSchema,
) -> Result<SpaceSchema>

widen over an already-advanced replay — the cache path: the study handle keeps one GrowthReplay beside its view and advances it per decision point, so the rule replays over new trials only (§10.3).

Errors

As widen.