feat: 雷达数据导出不限于 30 分的，可往前回退时间。

cmd/service-splitarea/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"database/sql"
 	"encoding/csv"
 	"encoding/json"
 	"errors"
@@ -185,14 +186,32 @@ func job(ctx context.Context, z, y, x int, bounds string, tzOffset int, outDir s
 	}
 	runAt = runAt.In(loc)
 
-	// Current hour's :30
-	targetLocal := runAt.Truncate(time.Hour).Add(30 * time.Minute)
-
-	// Fetch tile
-	rec, err := getRadarTileAt(ctx, z, y, x, targetLocal)
-	if err != nil {
-		return fmt.Errorf("load radar tile z=%d y=%d x=%d at %s: %w", z, y, x, targetLocal.Format("2006-01-02 15:04:05"), err)
+	// Prefer current hour's :30 tile, fallback to :24 then :00 if missing.
+	targetBase := runAt.Truncate(time.Hour)
+	candidates := []int{30, 24, 0}
+	var (
+		targetLocal time.Time
+		rec         *radarTileRecord
+	)
+	for _, minute := range candidates {
+		candidate := targetBase.Add(time.Duration(minute) * time.Minute)
+		tile, err := getRadarTileAt(ctx, z, y, x, candidate)
+		if err == nil {
+			if minute != candidates[0] {
+				log.Printf("[splitarea] fallback to %02d-minute radar tile at %s", minute, candidate.Format("2006-01-02 15:04:05"))
+			}
+			targetLocal = candidate
+			rec = tile
+			break
+		}
+		if !errors.Is(err, sql.ErrNoRows) {
+			return fmt.Errorf("load radar tile z=%d y=%d x=%d at %s: %w", z, y, x, candidate.Format("2006-01-02 15:04:05"), err)
+		}
 	}
+	if rec == nil {
+		return fmt.Errorf("no radar tile found for z=%d y=%d x=%d near %s (checked minutes %v)", z, y, x, targetBase.Format("2006-01-02 15:04:05"), candidates)
+	}
+
 	// Bounds
 	Bw, Bs, Be, Bn, err := parseBounds(bounds)
 	if err != nil {
@@ -226,7 +245,7 @@ func job(ctx context.Context, z, y, x int, bounds string, tzOffset int, outDir s
 		return fmt.Errorf("invalid tile data")
 	}
 
-	// Prepare output dir: export_data/split_area/YYYYMMDD/HH/30
+	// Prepare output dir: export_data/split_area/YYYYMMDD/HH/mm
 	ymd := targetLocal.Format("20060102")
 	hh := targetLocal.Format("15")
 	mm := targetLocal.Format("04")