Stabilize DCGM GPU discovery

audit/internal/platform/sat_test.go

@@ -162,6 +162,39 @@ func TestBuildNvidiaStressJobUsesNCCLLoader(t *testing.T) {
 	}
 }
 
+func TestResolveDCGMGPUIndicesUsesDetectedGPUsWhenUnset(t *testing.T) {
+	t.Parallel()
+
+	oldExecCommand := satExecCommand
+	satExecCommand = func(name string, args ...string) *exec.Cmd {
+		if name == "nvidia-smi" {
+			return exec.Command("sh", "-c", "printf '2\n0\n1\n'")
+		}
+		return exec.Command(name, args...)
+	}
+	t.Cleanup(func() { satExecCommand = oldExecCommand })
+
+	got, err := resolveDCGMGPUIndices(nil)
+	if err != nil {
+		t.Fatalf("resolveDCGMGPUIndices error: %v", err)
+	}
+	if want := "0,1,2"; joinIndexList(got) != want {
+		t.Fatalf("gpuIndices=%q want %q", joinIndexList(got), want)
+	}
+}
+
+func TestResolveDCGMGPUIndicesKeepsExplicitSelection(t *testing.T) {
+	t.Parallel()
+
+	got, err := resolveDCGMGPUIndices([]int{3, 1, 3})
+	if err != nil {
+		t.Fatalf("resolveDCGMGPUIndices error: %v", err)
+	}
+	if want := "1,3"; joinIndexList(got) != want {
+		t.Fatalf("gpuIndices=%q want %q", joinIndexList(got), want)
+	}
+}
+
 func TestNvidiaStressArchivePrefixByLoader(t *testing.T) {
 	t.Parallel()