Function gdn_decode_chunk2 

pub fn gdn_decode_chunk2(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    h_state: DevicePtr,
    query: DevicePtr,
    key: DevicePtr,
    value: DevicePtr,
    gate: DevicePtr,
    beta: DevicePtr,
    output: DevicePtr,
    h_state_intermediate: DevicePtr,
    batch_size: u32,
    num_k_heads: u32,
    num_v_heads: u32,
    k_dim: u32,
    v_dim: u32,
    qk_stride: u32,
    v_stride: u32,
    gb_stride: u32,
    stream: u64,
) -> Result<()>

2026-09-25: Two tokens through the GDN recurrence in one launch (gated_delta_rule_chunk2). The state after the first token is written to h_state_intermediate, for rollback when the draft is rejected. The strides are in elements, not bytes.