Function check_e4m3_range 

pub fn check_e4m3_range(
    gpu: &dyn GpuBackend,
    input: DevicePtr,
    elements: usize,
    stream: u64,
) -> Result<()>

2026-09-29: Debug builds: copy the elements BF16 values at input to the host on stream and panic when one exceeds E4M3_MAX in magnitude, unless an allow_e4m3_saturation scope covers it. NaN is not checked here. Skipped under graph capture, where a copy to the host cannot run. Release builds: a no-op.