fix(mileage): totalKm 当日为空时回填该车 ln_vehicle_day_total_pg 最近一条

视图 v_vehicle_daily_stats.total_km 仅当日有 TBOX 记录才有值，
否则原样为 NULL。新增 fetchLatestPgTotalMileageMap 在应用层按车牌
取最近一条非空 total_mileage（queryDateMileage 限定 dates <= 查询日，
保证历史日不取未来值），插入 gpsTotal → latestPgTotal → bizTotal 的
回退链，让 totalKm 显示连续。

MySQL 5.7 无窗口函数，用 INNER JOIN + GROUP BY MAX(dates) 取每车最近一条；
本地 dev 实测 1004 辆车 cache 刷新 ~16s，不再有 SQL 解析错。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/server/routes/mileage/cache.ts

@@ -80,11 +80,41 @@ async function fetchBizTotalMileageMap(): Promise<Map<string, number>> {
   return map;
 }
 
+async function fetchLatestPgTotalMileageMap(asOf?: string): Promise<Map<string, number>> {
+  // 当日 ln_vehicle_day_total_pg 无记录或 total_mileage 为 NULL 时，
+  // 回填该车 dates <= asOf 的最近一条非空 total_mileage（÷1000 转 km），
+  // 让视图 total_km 为 NULL 的车也能显示历史累计。
+  // MySQL 5.7 无窗口函数，用 GROUP BY MAX(dates) + JOIN 取每车最近一条。
+  const sql = `
+    SELECT t.plate_number, t.total_mileage
+    FROM ln_vehicle_day_total_pg t
+    INNER JOIN (
+      SELECT plate_number, MAX(dates) AS max_dates
+      FROM ln_vehicle_day_total_pg
+      WHERE total_mileage IS NOT NULL
+        ${asOf ? 'AND dates <= ?' : ''}
+      GROUP BY plate_number
+    ) m ON m.plate_number = t.plate_number AND m.max_dates = t.dates
+    WHERE t.total_mileage IS NOT NULL`;
+  const params = asOf ? [asOf] : [];
+  const [rows] = await mileagePool.execute(sql, params) as [
+    { plate_number: string; total_mileage: string | number | null }[],
+    unknown,
+  ];
+  const map = new Map<string, number>();
+  for (const r of rows) {
+    const km = Number(r.total_mileage) / 1000;
+    if (Number.isFinite(km) && km > 0) map.set(r.plate_number, km);
+  }
+  return map;
+}
+
 function mergeVehicles(
   mileageRows: MileageRow[],
   infoMap: Map<string, VehicleInfoRow>,
   yesterdayMap: Map<string, number>,
   bizTotalMap: Map<string, number>,
+  latestPgTotalMap: Map<string, number>,
 ): CachedVehicle[] {
   const mileageMap = new Map<string, MileageRow>();
   for (const row of mileageRows) {
@@ -99,12 +129,13 @@ function mergeVehicles(
     const dailyKm = Number(m.daily_km) || 0;
     const source = m.source || 'NONE';
     const gpsTotal = m.total_km !== null ? Number(m.total_km) : null;
+    const latestPgTotal = latestPgTotalMap.get(m.plate);
     const bizTotal = bizTotalMap.get(m.plate);
     return {
       plate: m.plate,
       vin: m.vin,
       dailyKm,
-      totalKm: gpsTotal !== null ? gpsTotal : (bizTotal ?? null),
+      totalKm: gpsTotal !== null ? gpsTotal : (latestPgTotal ?? bizTotal ?? null),
       source,
       isOnline: source !== 'NONE' && dailyKm > 0,
       isDataSynced: source !== 'NONE',
@@ -126,7 +157,7 @@ export async function refreshMonitoringCache(): Promise<void> {
     console.log('[mileage] refreshing monitoring cache...');
     const start = Date.now();
 
-    const [mileageRows, yesterdayMap, infoMap, targetRows, bizTotalMap] = await Promise.all([
+    const [mileageRows, yesterdayMap, infoMap, targetRows, bizTotalMap, latestPgTotalMap] = await Promise.all([
       (async () => {
         const [dateRows] = await mileagePool.execute(
           'SELECT MAX(stat_date) as latest FROM v_vehicle_daily_stats'
@@ -160,6 +191,7 @@ export async function refreshMonitoringCache(): Promise<void> {
          WHERE t.is_deleted = 0`
       ).then(([rows]) => rows as { id: number; target_name: string; plate_number: string }[]),
       fetchBizTotalMileageMap(),
+      fetchLatestPgTotalMileageMap(),
     ]);
 
     const targetPlatesMap = new Map<string, Set<string>>();
@@ -170,7 +202,7 @@ export async function refreshMonitoringCache(): Promise<void> {
     }
     const targetNames = Array.from(targetPlatesMap.keys());
 
-    const vehicles = mergeVehicles(mileageRows, infoMap, yesterdayMap, bizTotalMap);
+    const vehicles = mergeVehicles(mileageRows, infoMap, yesterdayMap, bizTotalMap, latestPgTotalMap);
     const totalToday = vehicles.reduce((sum, v) => sum + v.dailyKm, 0);
     const totalAll = vehicles.reduce((sum, v) => sum + (v.totalKm || 0), 0);
 
@@ -189,7 +221,7 @@ export async function refreshMonitoringCache(): Promise<void> {
 }
 
 export async function queryDateMileage(dateStr: string): Promise<CachedVehicle[]> {
-  const [mileageRows, yesterdayRows, infoMap, bizTotalMap] = await Promise.all([
+  const [mileageRows, yesterdayRows, infoMap, bizTotalMap, latestPgTotalMap] = await Promise.all([
     mileagePool.execute(
       'SELECT plate, vin, daily_km, total_km, source FROM v_vehicle_daily_stats WHERE stat_date = ?',
       [dateStr]
@@ -200,6 +232,7 @@ export async function queryDateMileage(dateStr: string): Promise<CachedVehicle[]
     ).then(([r]) => r as { plate: string; daily_km: string }[]),
     fetchVehicleInfoMap(),
     fetchBizTotalMileageMap(),
+    fetchLatestPgTotalMileageMap(dateStr),
   ]);
 
   const yesterdayMap = new Map<string, number>();
@@ -209,7 +242,7 @@ export async function queryDateMileage(dateStr: string): Promise<CachedVehicle[]
     if (km > existing) yesterdayMap.set(r.plate, km);
   }
 
-  return mergeVehicles(mileageRows, infoMap, yesterdayMap, bizTotalMap);
+  return mergeVehicles(mileageRows, infoMap, yesterdayMap, bizTotalMap, latestPgTotalMap);
 }
 
 export function buildDateFilters(vehicles: CachedVehicle[]): MonitoringFilters {