Function gdn_decode_wy4 

pub fn gdn_decode_wy4(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    h_state: DevicePtr,
    query: DevicePtr,
    key: DevicePtr,
    value: DevicePtr,
    gate: DevicePtr,
    beta: DevicePtr,
    output: DevicePtr,
    h_state_inter0: DevicePtr,
    h_state_inter1: DevicePtr,
    h_state_inter2: 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,
    state_is_table: bool,
    stream: u64,
) -> Result<()>

2026-09-25: WY-chunkwise 4-token verify decode (gated_delta_rule_wy4): the gdn_decode_wy2 scheme for four tokens, with three intermediate states.