fix: tighten source-aware mileage projection

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

@@ -19,9 +19,11 @@ type Execer interface {
 
 type Writer struct {
 	exec             Execer
+	query            Queryer
 	loc              *time.Location
 	mu               sync.Mutex
 	lastTotalMileage map[string]float64
+	baselineCache    map[string]sourceBaselineCacheEntry
 }
 
 type MetricSample struct {
@@ -43,7 +45,16 @@ func NewWriter(exec Execer, loc *time.Location) *Writer {
 	if loc == nil {
 		loc = time.FixedZone("Asia/Shanghai", 8*3600)
 	}
-	return &Writer{exec: exec, loc: loc, lastTotalMileage: map[string]float64{}}
+	writer := &Writer{
+		exec:             exec,
+		loc:              loc,
+		lastTotalMileage: map[string]float64{},
+		baselineCache:    map[string]sourceBaselineCacheEntry{},
+	}
+	if query, ok := exec.(Queryer); ok {
+		writer.query = query
+	}
+	return writer
 }
 
 func (w *Writer) EnsureSchema(ctx context.Context) error {
@@ -79,6 +90,9 @@ func (w *Writer) Append(ctx context.Context, env envelope.FrameEnvelope) error {
 				return err
 			}
 			candidate := SourceMileageSampleFromMetric(sample, identity)
+			if err := w.applyRealtimeBaseline(ctx, &candidate); err != nil {
+				return err
+			}
 			if err := UpsertSourceMileage(ctx, w.exec, candidate); err != nil {
 				return err
 			}
@@ -92,8 +106,7 @@ func (w *Writer) Append(ctx context.Context, env envelope.FrameEnvelope) error {
 }
 
 func (w *Writer) seenSameMileage(sample MetricSample) bool {
-	prefix := fmt.Sprintf("%s|%s|", sample.VIN, sample.Protocol)
-	key := prefix + sample.StatDate
+	key := mileageCacheKey(sample)
 	w.mu.Lock()
 	defer w.mu.Unlock()
 	if last, ok := w.lastTotalMileage[key]; ok && last == sample.TotalMileageKM {
@@ -103,8 +116,8 @@ func (w *Writer) seenSameMileage(sample MetricSample) bool {
 }
 
 func (w *Writer) markMileageWritten(sample MetricSample) {
-	prefix := fmt.Sprintf("%s|%s|", sample.VIN, sample.Protocol)
-	key := prefix + sample.StatDate
+	prefix := mileageCachePrefix(sample)
+	key := mileageCacheKey(sample)
 	w.mu.Lock()
 	defer w.mu.Unlock()
 	for existing := range w.lastTotalMileage {
@@ -112,9 +125,77 @@ func (w *Writer) markMileageWritten(sample MetricSample) {
 			delete(w.lastTotalMileage, existing)
 		}
 	}
+	for existing := range w.baselineCache {
+		if strings.HasPrefix(existing, prefix) && existing != key {
+			delete(w.baselineCache, existing)
+		}
+	}
 	w.lastTotalMileage[key] = sample.TotalMileageKM
 }
 
+func (w *Writer) applyRealtimeBaseline(ctx context.Context, candidate *SourceMileageSample) error {
+	if candidate == nil {
+		return nil
+	}
+	baseline, found, err := w.previousBaseline(ctx, *candidate)
+	if err != nil {
+		return err
+	}
+	if !found {
+		candidate.QualityStatus = QualityNoPreviousBaseline
+		candidate.QualityReason = "missing_previous_source"
+		return nil
+	}
+	candidate.FirstTotalKM = baseline.LatestTotalKM
+	candidate.FirstEventTime = baseline.LatestEventTime
+	candidate.DailyKM = candidate.LatestTotalKM - baseline.LatestTotalKM
+	candidate.QualityStatus = QualityOK
+	candidate.QualityReason = "same_source_previous_day"
+	if candidate.DailyKM < 0 || candidate.DailyKM > maxSelectedDailyMileageKM {
+		candidate.QualityStatus = QualityInvalidDelta
+		candidate.QualityReason = "outside_daily_range"
+	}
+	return nil
+}
+
+func (w *Writer) previousBaseline(ctx context.Context, candidate SourceMileageSample) (sourceBaseline, bool, error) {
+	cacheKey := mileageCacheKey(MetricSample{
+		VIN:       candidate.VIN,
+		Protocol:  candidate.Protocol,
+		StatDate:  candidate.StatDate,
+		SourceKey: candidate.SourceKey,
+	})
+	w.mu.Lock()
+	if cached, ok := w.baselineCache[cacheKey]; ok {
+		w.mu.Unlock()
+		return cached.baseline, cached.found, nil
+	}
+	w.mu.Unlock()
+
+	baseline, found, err := lookupPreviousSourceBaseline(ctx, w.query, candidate.VIN, candidate.StatDate, candidate.Protocol, candidate.SourceKey)
+	if err != nil {
+		return sourceBaseline{}, false, err
+	}
+
+	w.mu.Lock()
+	w.baselineCache[cacheKey] = sourceBaselineCacheEntry{baseline: baseline, found: found}
+	w.mu.Unlock()
+	return baseline, found, nil
+}
+
+func mileageCachePrefix(sample MetricSample) string {
+	return fmt.Sprintf("%s|%s|%s|", sample.VIN, sample.Protocol, sample.SourceKey)
+}
+
+func mileageCacheKey(sample MetricSample) string {
+	return mileageCachePrefix(sample) + sample.StatDate
+}
+
+type sourceBaselineCacheEntry struct {
+	baseline sourceBaseline
+	found    bool
+}
+
 func SamplesFromEnvelope(env envelope.FrameEnvelope, loc *time.Location) ([]MetricSample, error) {
 	vin := strings.TrimSpace(env.VIN)
 	if vin == "" {