fix(go): collapse gb32960 auxiliary snapshot

go/vehicle-gateway/internal/realtime/repository_test.go

@@ -271,6 +271,53 @@ func TestRepositoryCollapsesGB32960VendorStackFragmentsIntoSingleRealtimeSummary
 	}
 }
 
+func TestRepositoryReplacesGB32960VendorAuxiliarySubsystemsWithLatestState(t *testing.T) {
+	repo, closeFn := newTestRepository(t)
+	defer closeFn()
+	ctx := context.Background()
+
+	for i, voltage := range []float64{372, 348} {
+		if err := repo.Update(ctx, envelope.FrameEnvelope{
+			Protocol:     envelope.ProtocolGB32960,
+			VIN:          "VIN001",
+			EventTimeMS:  int64(1000 + i),
+			ReceivedAtMS: int64(1100 + i),
+			Parsed: map[string]any{
+				"data_units": []any{
+					map[string]any{
+						"type": "0x31",
+						"name": "gd_fc_auxiliary",
+						"value": map[string]any{
+							"subsystem_count": 1,
+							"subsystems": []any{map[string]any{
+								"air_compressor_motor_voltage_v": voltage,
+								"water_pump_voltage_v":           voltage,
+							}},
+						},
+					},
+				},
+			},
+		}); err != nil {
+			t.Fatalf("Update() error = %v", err)
+		}
+	}
+
+	realtimeRaw, err := repo.GetRealtimeRaw(ctx, "VIN001", envelope.ProtocolGB32960)
+	if err != nil {
+		t.Fatalf("GetRealtimeRaw() error = %v", err)
+	}
+	unit := realtimeRaw["data_units"].([]any)[0].(map[string]any)
+	value := unit["value"].(map[string]any)
+	subsystems := value["subsystems"].([]any)
+	if len(subsystems) != 1 {
+		t.Fatalf("auxiliary subsystems should keep current state, not append historical frames: %#v", subsystems)
+	}
+	subsystem := subsystems[0].(map[string]any)
+	if subsystem["air_compressor_motor_voltage_v"] != float64(348) {
+		t.Fatalf("auxiliary subsystem should keep latest values: %#v", subsystem)
+	}
+}
+
 func TestRepositoryWritesRealtimeKVHashes(t *testing.T) {
 	repo, closeFn := newTestRepository(t)
 	defer closeFn()