Function expert_router_bytes 

pub fn expert_router_bytes(
    cfg: &ModelConfig,
    expert_keys: &[(usize, ExpertProj)],
    router_layers: &[usize],
    max_rank: usize,
) -> usize

2026-09-25: Padded bytes of the expert/router pool for the given audited keys: (stride * in + out * stride) * 2 per expert key and per router layer. stride is expert_pack::packed_stride(max_rank), the stride expert_pack::pack_into advances by, so the size matches what is packed.