fix(platform): count source online by protocol

vehicle-data-platform/apps/api/internal/platform/service_test.go

@@ -64,3 +64,22 @@ func TestVehicleServiceOverviewsUsesBatchDataPath(t *testing.T) {
 		t.Fatalf("batch overview should avoid per-keyword store calls, vehicles=%d realtime=%d", store.vehiclesCalls, store.vehicleRealtimeCalls)
 	}
 }
+
+func TestVehicleServiceSummaryCountsProtocolOnlineByProtocolSlot(t *testing.T) {
+	service := NewService(NewMockStore())
+	summary, err := service.VehicleServiceSummary(context.Background())
+	if err != nil {
+		t.Fatalf("VehicleServiceSummary returned error: %v", err)
+	}
+	byProtocol := map[string]ProtocolStat{}
+	for _, protocol := range summary.Protocols {
+		byProtocol[protocol.Protocol] = protocol
+	}
+	gb32960 := byProtocol["GB32960"]
+	if gb32960.Total != 2 {
+		t.Fatalf("expected two GB32960 source slots, got %+v", gb32960)
+	}
+	if gb32960.Online != 1 {
+		t.Fatalf("GB32960 online count must use GB32960 source status only, got %+v", gb32960)
+	}
+}