feat(go): add realtime pipeline observability

go/vehicle-gateway/cmd/realtime-api/main_test.go

@@ -102,7 +102,8 @@ func TestAsyncSecondaryRealtimeUpdaterDoesNotBlockPrimaryPath(t *testing.T) {
 	env := envelope.FrameEnvelope{Protocol: envelope.ProtocolGB32960, VIN: "VIN001"}
 	primary := &contextCheckingRealtimeUpdater{}
 	secondary := &blockingRealtimeUpdater{started: make(chan struct{}), release: make(chan struct{})}
-	updater := newAsyncSecondaryRealtimeUpdater(primary, secondary, 8, 1)
+	registry := metrics.NewRegistry()
+	updater := newAsyncSecondaryRealtimeUpdater(primary, secondary, 8, 1, registry)
 	defer updater.Close()
 
 	start := time.Now()
@@ -121,6 +122,26 @@ func TestAsyncSecondaryRealtimeUpdaterDoesNotBlockPrimaryPath(t *testing.T) {
 		t.Fatal("secondary update was not started asynchronously")
 	}
 	close(secondary.release)
+	if text := registry.Render(); !strings.Contains(text, `vehicle_realtime_async_queue_total{protocol="GB32960",status="queued",store="mysql"} 1`) {
+		t.Fatalf("async queue metric missing:\n%s", text)
+	}
+}
+
+func TestStoreMetricUpdaterRecordsStoreUpdateResults(t *testing.T) {
+	registry := metrics.NewRegistry()
+	env := envelope.FrameEnvelope{Protocol: envelope.ProtocolJT808, VIN: "VIN001"}
+	updater := storeMetricUpdater{
+		store:    "redis",
+		delegate: &contextCheckingRealtimeUpdater{},
+		registry: registry,
+	}
+
+	if err := updater.Update(context.Background(), env); err != nil {
+		t.Fatalf("Update() error = %v", err)
+	}
+	if text := registry.Render(); !strings.Contains(text, `vehicle_realtime_store_updates_total{protocol="JT808",status="ok",store="redis"} 1`) {
+		t.Fatalf("store update metric missing:\n%s", text)
+	}
 }
 
 func TestKafkaTopicsFromEnvDefaultsToGoRawTopics(t *testing.T) {
@@ -174,6 +195,18 @@ func TestRealtimeAPIExposesPostRawFrameQueryRoute(t *testing.T) {
 	}
 }
 
+func TestRealtimeAPIExposesOperationalRealtimeRoutes(t *testing.T) {
+	source, err := os.ReadFile("main.go")
+	if err != nil {
+		t.Fatalf("read main.go: %v", err)
+	}
+	for _, want := range []string{`"/api/realtime/online"`, `"/api/debug/pipeline"`} {
+		if !strings.Contains(string(source), want) {
+			t.Fatalf("realtime api should expose operational route %s", want)
+		}
+	}
+}
+
 type contextCheckingRealtimeUpdater struct {
 	ctxErr error
 	count  int