Function gen_qwen38_decode_step_lg 

pub fn gen_qwen38_decode_step_lg(
    cfg: &Qwen38Cfg,
    dir: &str,
    ctx: usize,
    tok: usize,
    pos: usize,
) -> Authored

One decode step: token tok at position pos (1-based) in, the next token out, the KV caches and the Gated-DeltaNet state carried. See author::decode_step.