diff --git a/src/main/java/com/ffii/fpsms/modules/stock/service/StockInLineService.kt b/src/main/java/com/ffii/fpsms/modules/stock/service/StockInLineService.kt
index 74dbc93..6a73472 100644
--- a/src/main/java/com/ffii/fpsms/modules/stock/service/StockInLineService.kt
+++ b/src/main/java/com/ffii/fpsms/modules/stock/service/StockInLineService.kt
@@ -96,9 +96,18 @@ open class StockInLineService(
 
     open fun assignLotNo(): String {
         val prefix = "LT"
-        val midfix = CodeGenerator.DEFAULT_MIDFIX
-        val latestCode = inventoryLotRepository.findLatestLotNoByPrefix("${prefix}-${midfix}")
-        return CodeGenerator.generateNo(prefix = prefix, latestCode = latestCode)
+        // ✅ 每次调用都取今天的日期段
+        val midfix = LocalDate.now().format(CodeGenerator.DEFAULT_FORMATTER)
+    
+        // ✅ 用同一个 midfix 去查最新记录
+        val latestCode = inventoryLotRepository.findLatestLotNoByPrefix("$prefix-$midfix")
+    
+        // ✅ 并且把同一个 midfix 传给 CodeGenerator
+        return CodeGenerator.generateNo(
+            prefix = prefix,
+            midfix = midfix,
+            latestCode = latestCode
+        )
     }
 
     @Throws(IOException::class)
@@ -791,7 +800,7 @@ open class StockInLineService(
 
         // Step 2: Create a row in stock_in_line table
         val item = itemRepository.findById(request.itemId).orElseThrow()
-
+        val newLotNo = request.lotNo ?: assignLotNo()
         val stockInLine = StockInLine().apply {
             this.item = item
             this.itemNo = request.itemNo
@@ -802,7 +811,7 @@ open class StockInLineService(
             this.productionDate = LocalDateTime.now()
             this.expiryDate = request.expiryDate
             this.status = StockInLineStatus.COMPLETE.status
-            this.lotNo = request.lotNo ?: assignLotNo()
+            this.lotNo = newLotNo
             this.productLotNo = request.productLotNo
             this.dnNo = request.dnNo
             this.type = request.type
@@ -811,7 +820,7 @@ open class StockInLineService(
 
 
         // Step 3: Create a row in inventory_lot table
-        val lotNo = request.lotNo ?: assignLotNo()
+        val lotNo = newLotNo
         val inventoryLot = InventoryLot().apply {
             this.item = item
             this.stockInLine = savedStockInLine