fix: materialize stationary yutong daily mileage

go/vehicle-gateway/internal/stats/daily_metric.go

@@ -69,6 +69,7 @@ type AppendResult struct {
 	SamplesSkippedMissingFields      int
 	SamplesSkippedMissingVIN         int
 	SamplesSkippedMissingMileage     int
+	SamplesRecoveredStationary       int
 	SamplesSkippedNonMileageFrame    int
 	SamplesSkippedNonPositiveMileage int
 	SamplesSkippedMissingTime        int
@@ -282,6 +283,19 @@ func (w *Writer) AppendWithResult(ctx context.Context, env envelope.FrameEnvelop
 	if err != nil {
 		return result, err
 	}
+	var stationaryCandidate *SourceMileageSample
+	if len(samples) == 0 && hasSource && result.SamplesSkippedMissingMileage > 0 {
+		sample, candidate, recovered, recoverErr := w.stationaryCarryForward(ctx, env, identity)
+		if recoverErr != nil {
+			return result, recoverErr
+		}
+		if recovered {
+			samples = []MetricSample{sample}
+			stationaryCandidate = &candidate
+			result.SamplesFound++
+			result.SamplesRecoveredStationary++
+		}
+	}
 	for _, sample := range samples {
 		if !hasSource {
 			result.SamplesSkippedMissingSource++
@@ -293,8 +307,12 @@ func (w *Writer) AppendWithResult(ctx context.Context, env envelope.FrameEnvelop
 			continue
 		}
 		candidate := SourceMileageSampleFromMetric(sample, identity)
-		if err := w.applyRealtimeBaseline(ctx, &candidate); err != nil {
-			return result, err
+		if stationaryCandidate != nil {
+			candidate = *stationaryCandidate
+		} else {
+			if err := w.applyRealtimeBaseline(ctx, &candidate); err != nil {
+				return result, err
+			}
 		}
 		projectDaily := w.shouldProjectDailyMileage(sample)
 		if projectDaily {
@@ -316,6 +334,47 @@ func (w *Writer) AppendWithResult(ctx context.Context, env envelope.FrameEnvelop
 	return result, nil
 }
 
+func (w *Writer) stationaryCarryForward(ctx context.Context, env envelope.FrameEnvelope, identity SourceIdentity) (MetricSample, SourceMileageSample, bool, error) {
+	if env.Protocol != envelope.ProtocolYutongMQTT || strings.TrimSpace(env.VIN) == "" {
+		return MetricSample{}, SourceMileageSample{}, false, nil
+	}
+	location, ok := telemetry.LocationProjectionForProtocol(env.Protocol, env.Fields)
+	if !ok || location.SpeedKMH == nil || *location.SpeedKMH != 0 {
+		return MetricSample{}, SourceMileageSample{}, false, nil
+	}
+	eventMS, _, ok := envelope.NormalizedEventTimeMSWithReason(env)
+	if !ok {
+		return MetricSample{}, SourceMileageSample{}, false, nil
+	}
+	eventTime := time.UnixMilli(eventMS).In(w.loc)
+	sample := MetricSample{
+		VIN:            strings.TrimSpace(env.VIN),
+		Protocol:       env.Protocol,
+		StatDate:       eventTime.Format("2006-01-02"),
+		EventTime:      eventTime,
+		SourceKey:      SourceKeyForSource(env.Protocol, env.Phone, env.DeviceID, identity.SourceIP, identity.SourceKind, identity.SourceCode),
+		Phone:          strings.TrimSpace(env.Phone),
+		DeviceID:       strings.TrimSpace(env.DeviceID),
+		SourceEndpoint: strings.TrimSpace(env.SourceEndpoint),
+		PlatformName:   strings.TrimSpace(env.PlatformName),
+	}
+	candidate := SourceMileageSampleFromMetric(sample, identity)
+	baseline, found, err := w.previousBaseline(ctx, candidate)
+	if err != nil || !found || baseline.LatestTotalKM <= 0 || baseline.LatestEventTime.IsZero() {
+		return MetricSample{}, SourceMileageSample{}, false, err
+	}
+	sample.TotalMileageKM = baseline.LatestTotalKM
+	candidate = SourceMileageSampleFromMetric(sample, identity)
+	candidate.FirstTotalKM = baseline.LatestTotalKM
+	candidate.LatestTotalKM = baseline.LatestTotalKM
+	candidate.DailyKM = 0
+	candidate.FirstEventTime = baseline.LatestEventTime
+	candidate.LatestEventTime = eventTime
+	candidate.QualityStatus = QualityOK
+	candidate.QualityReason = QualityReasonStationaryCarry
+	return sample, candidate, true, nil
+}
+
 func (w *Writer) writeMileageSample(ctx context.Context, sample MetricSample, candidate SourceMileageSample, projectDaily bool) error {
 	if projectDaily {
 		if beginner, ok := w.exec.(txBeginner); ok {