Reject software renderers in GPU probe (only accept DiscreteGpu/IntegratedGpu)

Author: ciaranra

crates/pecos-gpu-sims/src/gpu_probe.rs

@@ -61,6 +61,32 @@ pub fn request_default_gpu_device(
         device_type: info.device_type,
     };
 
+    // Reject software renderers and unknown device types -- they technically
+    // "work" but OOM on real workloads (common on CI runners without real GPUs)
+    match info.device_type {
+        wgpu::DeviceType::DiscreteGpu | wgpu::DeviceType::IntegratedGpu => {}
+        other => {
+            return Err(GpuStartupError::DeviceCreation {
+                info,
+                error: format!("Device type {other:?} is not a hardware GPU"),
+            });
+        }
+    }
+
+    // Check buffer limits -- real GPUs support at least 128MB storage buffers.
+    // Software renderers or broken drivers may report very low limits.
+    let limits = adapter.limits();
+    let min_buffer_mb = 128;
+    if limits.max_storage_buffer_binding_size < min_buffer_mb * 1024 * 1024 {
+        return Err(GpuStartupError::DeviceCreation {
+            info,
+            error: format!(
+                "GPU storage buffer limit too small ({} MB, need at least {min_buffer_mb} MB)",
+                limits.max_storage_buffer_binding_size / 1024 / 1024
+            ),
+        });
+    }
+
     let (device, queue) = pollster::block_on(adapter.request_device(&wgpu::DeviceDescriptor {
         label: Some(label),
         required_features: wgpu::Features::empty(),