fix(stats): preserve realtime baseline from current candidate

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

@@ -318,6 +318,35 @@ func lookupPreviousSourceBaseline(ctx context.Context, query Queryer, vin string
 	}, latestTotal.Valid, nil
 }
 
+func lookupCurrentSourceBaseline(ctx context.Context, query Queryer, vin string, statDate string, protocol envelope.Protocol, sourceKey string) (sourceBaseline, bool, error) {
+	if query == nil || strings.TrimSpace(vin) == "" || strings.TrimSpace(statDate) == "" || strings.TrimSpace(sourceKey) == "" {
+		return sourceBaseline{}, false, nil
+	}
+	rows, err := query.QueryContext(ctx, currentSourceBaselineSQL, vin, statDate, string(protocol), sourceKey)
+	if err != nil {
+		return sourceBaseline{}, false, err
+	}
+	defer rows.Close()
+	if !rows.Next() {
+		if err := rows.Err(); err != nil {
+			return sourceBaseline{}, false, err
+		}
+		return sourceBaseline{}, false, nil
+	}
+	var firstTotal sql.NullFloat64
+	var firstEvent sql.NullTime
+	if err := rows.Scan(&firstTotal, &firstEvent); err != nil {
+		return sourceBaseline{}, false, err
+	}
+	if err := rows.Err(); err != nil {
+		return sourceBaseline{}, false, err
+	}
+	return sourceBaseline{
+		LatestTotalKM:   firstTotal.Float64,
+		LatestEventTime: firstEvent.Time,
+	}, firstTotal.Valid, nil
+}
+
 func previousStatDate(statDate string) (string, bool) {
 	day, err := time.Parse("2006-01-02", strings.TrimSpace(statDate))
 	if err != nil {
@@ -336,3 +365,15 @@ WHERE vin = ?
 ORDER BY latest_event_time DESC
 LIMIT 1
 `
+
+const currentSourceBaselineSQL = `
+SELECT first_total_mileage_km, first_event_time
+FROM vehicle_daily_mileage_source
+WHERE vin = ?
+  AND stat_date = ?
+  AND protocol = ?
+  AND source_key = ?
+  AND quality_status = '` + QualityOK + `'
+ORDER BY latest_event_time DESC
+LIMIT 1
+`