feat(go): expose runtime ingest metrics

go/vehicle-gateway/internal/gateway/mqtt_client_test.go

@@ -11,10 +11,12 @@ import (
 	"math/big"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 	"time"
 
 	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
+	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/metrics"
 )
 
 func TestMQTTClientHandleMessagePublishesRawAndUnified(t *testing.T) {
@@ -45,6 +47,39 @@ func TestMQTTClientHandleMessagePublishesRawAndUnified(t *testing.T) {
 	}
 }
 
+func TestMQTTClientRecordsMessageMetrics(t *testing.T) {
+	registry := metrics.NewRegistry()
+	client, err := NewMQTTClient(MQTTClientConfig{
+		EndpointName: "endpoint-a",
+		Broker:       "tcp://127.0.0.1:1883",
+		ClientID:     "test-client",
+		Topics:       []string{"/ytforward/shln/+"},
+		Sink:         &recordingSink{},
+		Logger:       slog.New(slog.NewTextHandler(testWriter{t: t}, nil)),
+		Metrics:      registry,
+	})
+	if err != nil {
+		t.Fatalf("NewMQTTClient() error = %v", err)
+	}
+
+	client.handleMessage(context.Background(), "/ytforward/shln/dev1", []byte(`{
+	  "device":"LTEST000000000001",
+	  "time":"20260413100000",
+	  "data":{"METER_SPEED":52.3,"TOTAL_MILEAGE":123456.7}
+	}`))
+
+	text := registry.Render()
+	for _, want := range []string{
+		`vehicle_gateway_frames_total{protocol="YUTONG_MQTT",status="OK"} 1`,
+		`vehicle_gateway_publish_total{kind="raw",protocol="YUTONG_MQTT",status="ok"} 1`,
+		`vehicle_gateway_publish_total{kind="unified",protocol="YUTONG_MQTT",status="ok"} 1`,
+	} {
+		if !strings.Contains(text, want) {
+			t.Fatalf("metrics missing %s:\n%s", want, text)
+		}
+	}
+}
+
 func TestMQTTClientHandleBadPayloadPublishesOnlyRaw(t *testing.T) {
 	sink := &recordingSink{}
 	client, err := NewMQTTClient(MQTTClientConfig{