Function compute_decode_token_host 

pub fn compute_decode_token_host<M: DecodeBackbone + ?Sized>(
    model: &M,
    cached_len: usize,
    tokens: &[u32],
    max_seq_len: usize,
    rope_inv_freq: Option<&[f64]>,
) -> DecodeTokenHost

Compute one decode step’s host-side data — the RoPE tables and the stacked mask. Pure host math, no graph and no upload, shared by the build path (which bakes or uploads it) and every family’s rebind hook (which uploads it).