fix: tighten source-aware mileage projection

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

@@ -2,6 +2,7 @@ package stats
 
 import (
 	"context"
+	"database/sql"
 	"strings"
 	"time"
 
@@ -127,6 +128,17 @@ func ProjectDailyMileage(ctx context.Context, exec Execer, vin string, statDate
 		statDate,
 		string(protocol),
 	)
+	if err != nil {
+		return err
+	}
+	_, err = exec.ExecContext(ctx, cleanupProjectedDailyMileageSQL,
+		vin,
+		statDate,
+		string(protocol),
+		vin,
+		statDate,
+		string(protocol),
+	)
 	return err
 }
 
@@ -257,3 +269,70 @@ JOIN (
 SET s.is_selected = 1
 WHERE s.vin = ? AND s.stat_date = ? AND s.protocol = ?
 `
+
+const cleanupProjectedDailyMileageSQL = `
+DELETE FROM vehicle_daily_mileage
+WHERE vin = ? AND stat_date = ? AND protocol = ?
+  AND NOT EXISTS (
+    SELECT 1
+    FROM vehicle_daily_mileage_source
+    WHERE vin = ? AND stat_date = ? AND protocol = ? AND is_selected = 1
+  )
+`
+
+type sourceBaseline struct {
+	LatestTotalKM   float64
+	LatestEventTime time.Time
+}
+
+func lookupPreviousSourceBaseline(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
+	}
+	previousDate, ok := previousStatDate(statDate)
+	if !ok {
+		return sourceBaseline{}, false, nil
+	}
+	rows, err := query.QueryContext(ctx, previousSourceBaselineSQL, vin, previousDate, 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 latestTotal sql.NullFloat64
+	var latestEvent sql.NullTime
+	if err := rows.Scan(&latestTotal, &latestEvent); err != nil {
+		return sourceBaseline{}, false, err
+	}
+	if err := rows.Err(); err != nil {
+		return sourceBaseline{}, false, err
+	}
+	return sourceBaseline{
+		LatestTotalKM:   latestTotal.Float64,
+		LatestEventTime: latestEvent.Time,
+	}, latestTotal.Valid, nil
+}
+
+func previousStatDate(statDate string) (string, bool) {
+	day, err := time.Parse("2006-01-02", strings.TrimSpace(statDate))
+	if err != nil {
+		return "", false
+	}
+	return day.AddDate(0, 0, -1).Format("2006-01-02"), true
+}
+
+const previousSourceBaselineSQL = `
+SELECT latest_total_mileage_km, latest_event_time
+FROM vehicle_daily_mileage_source
+WHERE vin = ?
+  AND stat_date = ?
+  AND protocol = ?
+  AND source_key = ?
+ORDER BY latest_event_time DESC
+LIMIT 1
+`