Function emit_qwen38_generate_batched_q4 

pub fn emit_qwen38_generate_batched_q4(
    cfg: &Qwen38Cfg,
    wdir: &str,
    prompt: &[usize],
    n_gen: usize,
    batch: usize,
    hl: bool,
    prefill_t: usize,
    mtp: bool,
    q4: bool,
) -> String

Every lane choice explicit — the form the compile gate and the equivalence locks drive.