Add GPU preflight diagnostics

scripts/preflight_gpu.py

@@ -0,0 +1,27 @@
+"""GPU preflight diagnostics for Nomen-AI training.
+
+Run before smoke/SFT/DPO to fail early if CUDA or VRAM is unavailable.
+"""
+import sys
+import torch
+
+
+def main():
+    print('torch:', torch.__version__)
+    print('cuda_available:', torch.cuda.is_available())
+    if not torch.cuda.is_available():
+        raise SystemExit('ERROR: CUDA is not available. Use a Colab GPU/T4 runtime or Docker with NVIDIA runtime.')
+    device = torch.cuda.current_device()
+    name = torch.cuda.get_device_name(device)
+    props = torch.cuda.get_device_properties(device)
+    total_gb = props.total_memory / 1e9
+    print('gpu_name:', name)
+    print('total_vram_gb:', round(total_gb, 2))
+    print('compute_capability:', f'{props.major}.{props.minor}')
+    if total_gb < 14:
+        raise SystemExit(f'ERROR: VRAM {total_gb:.1f}GB is below expected T4-class 15GB. Use T4/A10G or larger.')
+    print('GPU_PREFLIGHT_PASS')
+
+
+if __name__ == '__main__':
+    main()