Function admits_pinned 

pub fn admits_pinned(
    cfg: &OptimizationConfig,
    hs: &HotswapConfig,
    tier: Tier,
    opt: Opt,
) -> bool

admits with per-opt pins applied: a pin overrides the cost-derived tier (HOTSWAP §8). A disabled opt (!cfg.is_on) never runs regardless of pin, so ## No <opt> always wins over ## Tier <opt> eager.