Keep chart series colors stable

audit/internal/webui/server_test.go

@@ -89,6 +89,53 @@ func TestChartDataFromSamplesUsesFullHistory(t *testing.T) {
 	}
 }
 
+func TestChartDataFromSamplesKeepsStableGPUSeriesOrder(t *testing.T) {
+	samples := []platform.LiveMetricSample{
+		{
+			Timestamp: time.Now().Add(-2 * time.Minute),
+			GPUs: []platform.GPUMetricRow{
+				{GPUIndex: 7, PowerW: 170},
+				{GPUIndex: 2, PowerW: 120},
+				{GPUIndex: 0, PowerW: 100},
+			},
+		},
+		{
+			Timestamp: time.Now().Add(-1 * time.Minute),
+			GPUs: []platform.GPUMetricRow{
+				{GPUIndex: 0, PowerW: 101},
+				{GPUIndex: 7, PowerW: 171},
+				{GPUIndex: 2, PowerW: 121},
+			},
+		},
+	}
+
+	datasets, names, _, title, _, _, ok := chartDataFromSamples("gpu-all-power", samples)
+	if !ok {
+		t.Fatal("chartDataFromSamples returned ok=false")
+	}
+	if title != "GPU Power" {
+		t.Fatalf("title=%q", title)
+	}
+	wantNames := []string{"GPU 0", "GPU 2", "GPU 7"}
+	if len(names) != len(wantNames) {
+		t.Fatalf("names len=%d want %d: %v", len(names), len(wantNames), names)
+	}
+	for i := range wantNames {
+		if names[i] != wantNames[i] {
+			t.Fatalf("names[%d]=%q want %q; full=%v", i, names[i], wantNames[i], names)
+		}
+	}
+	if got := datasets[0]; len(got) != 2 || got[0] != 100 || got[1] != 101 {
+		t.Fatalf("GPU 0 dataset=%v want [100 101]", got)
+	}
+	if got := datasets[1]; len(got) != 2 || got[0] != 120 || got[1] != 121 {
+		t.Fatalf("GPU 2 dataset=%v want [120 121]", got)
+	}
+	if got := datasets[2]; len(got) != 2 || got[0] != 170 || got[1] != 171 {
+		t.Fatalf("GPU 7 dataset=%v want [170 171]", got)
+	}
+}
+
 func TestNormalizePowerSeriesHoldsLastPositive(t *testing.T) {
 	got := normalizePowerSeries([]float64{0, 480, 0, 0, 510, 0})
 	want := []float64{0, 480, 480, 480, 510, 510}