Function moe_permute_tokens 

pub fn moe_permute_tokens(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    hidden_states: DevicePtr,
    permuted: DevicePtr,
    sorted_token_ids: DevicePtr,
    hidden: u32,
    total_expanded: u32,
    stream: u64,
) -> Result<()>

2026-09-25: Gather token rows into expert-sorted order: permuted[i] = hidden[sorted_token_ids[i]], permuted being [total_expanded, hidden]. One block per output row. No code calls it.