Require executable CUDA for GPU mode

tests/test_node_startup.py

@@ -12,6 +12,7 @@ import pytest
 from meshnet_node.downloader import download_shard, write_shard_archive
 from meshnet_node.hardware import detect_hardware, benchmark_throughput
 from meshnet_node.startup import (
+    _hardware_label,
     _infer_relay_url_from_tracker,
     _memory_budget,
     _probationary_status_line,
@@ -98,6 +99,29 @@ def test_windows_gpu_memory_fallback_preserves_cpu_execution(monkeypatch):
     assert hw["ram_mb"] == 80 * 1024
 
 
+def test_nvidia_smi_without_torch_cuda_keeps_cpu_execution(monkeypatch):
+    """nvidia-smi proves GPU inventory, not that this Python can execute CUDA."""
+    import meshnet_node.hardware as hardware_mod
+
+    class FakeResult:
+        returncode = 0
+        stdout = "NVIDIA GeForce RTX 4060 Laptop GPU, 8188\n"
+
+    fake_torch = types.SimpleNamespace(cuda=types.SimpleNamespace(is_available=lambda: False))
+
+    monkeypatch.setattr(hardware_mod, "_detect_ram_mb", lambda: 80 * 1024)
+    monkeypatch.setattr(hardware_mod.subprocess, "run", lambda *a, **kw: FakeResult())
+    monkeypatch.setitem(sys.modules, "torch", fake_torch)
+
+    hw = hardware_mod.detect_hardware()
+
+    assert hw["device"] == "cpu"
+    assert hw["cuda_available"] is False
+    assert hw["gpu_name"] == "NVIDIA GeForce RTX 4060 Laptop GPU"
+    assert hw["vram_mb"] == 8188
+    assert hw["ram_mb"] == 80 * 1024
+
+
 def test_memory_budget_uses_ram_for_cpu_and_shared_memory_for_cuda():
     assert _memory_budget("cpu", vram_mb=8192, ram_mb=80 * 1024, shared_vram_mb=40 * 1024) == (
         80 * 1024,
@@ -109,6 +133,12 @@ def test_memory_budget_uses_ram_for_cpu_and_shared_memory_for_cuda():
     )
 
 
+def test_hardware_label_marks_inventory_only_gpu_as_cuda_inactive():
+    assert _hardware_label("cpu", "NVIDIA GeForce RTX 4060 Laptop GPU") == "CPU (CUDA inactive)"
+    assert _hardware_label("cpu", None) == "CPU"
+    assert _hardware_label("cuda", "NVIDIA GeForce RTX 4060 Laptop GPU") == "CUDA"
+
+
 def test_benchmark_throughput_cpu_returns_positive():
     """CPU benchmark returns a positive float greater than the 1.0 error fallback."""
     result = benchmark_throughput("cpu")