Function export_slice_managed_tensor 

pub fn export_slice_managed_tensor(
    slice: Arc<TrackedCudaSlice<u8>>,
    device_id: i32,
    dtype: DLDataType,
    rows: usize,
    cols: usize,
) -> Result<DlpackManagedTensor>

Export an xlog-owned runtime-backed slice as a 2-D DLPack managed tensor without copies. The manager context holds the slice’s Arc, so the export shares the exact producer allocation and the memory stays alive until the consumer’s deleter runs; xlog remains the owner throughout. The declared rows x cols x dtype view must cover the allocation exactly — a mismatched shape is a typed error, never a truncated or padded view.