diff --git a/lastleg-service/src/main/java/com/baiyue/lastleg/delivery/service/DeliveryTransferService.java b/lastleg-service/src/main/java/com/baiyue/lastleg/delivery/service/DeliveryTransferService.java
index 56aea78ef..aac663016 100644
--- a/lastleg-service/src/main/java/com/baiyue/lastleg/delivery/service/DeliveryTransferService.java
+++ b/lastleg-service/src/main/java/com/baiyue/lastleg/delivery/service/DeliveryTransferService.java
@@ -516,6 +516,8 @@ public class DeliveryTransferService {
         existing = outboundOrders.findByIdempotency(customerId, request.idempotencyKey().trim());
         if (existing != null) return replayReturnOutbound(customerId, existing, requestHash);
         for (ReturnInventoryCarton carton : locked) {
+            if (StringUtils.hasText(request.skuCode()) && !"PARCEL".equals(carton.getSourceUnitType()))
+                throw conflict("单SKU出库只允许散件库存；箱内库存请按箱或托盘出库");
             if ("PARCEL".equals(carton.getSourceUnitType()) && !StringUtils.hasText(request.skuCode()))
                 throw conflict("包裹散件只能按 SKU 出库，不能按箱号或托盘出库");
             com.baiyue.lastleg.returnreceipt.service.ReturnCartonCountGuard.requireConfirmed(carton);
@@ -525,7 +527,7 @@ public class DeliveryTransferService {
                 throw conflict("退货箱缺少明细或已被合箱计划锁定：" + carton.getCartonMark());
             if (StringUtils.hasText(request.skuCode()) && (contents.size() != 1
                 || !request.skuCode().trim().equals(contents.get(0).getSkuCode())))
-                throw conflict("单SKU出库只支持箱内仅有指定SKU的库存；混合箱请先拆箱");
+                throw conflict("所选散件来源必须仅包含指定SKU");
             if ("PALLET".equals(request.unitType()) && !StringUtils.hasText(carton.getPalletCode()))
                 throw conflict("整托出库必须存在托盘绑定");
         }
diff --git a/lastleg-service/src/main/resources/openapi/overseas-business-v1.yaml b/lastleg-service/src/main/resources/openapi/overseas-business-v1.yaml
index 8396cd8d5..42d611a1c 100644
--- a/lastleg-service/src/main/resources/openapi/overseas-business-v1.yaml
+++ b/lastleg-service/src/main/resources/openapi/overseas-business-v1.yaml
@@ -825,7 +825,7 @@ paths:
   /api/platform/v1/last-leg/outbound-orders/return:
     post:
       summary: 创建退货出库单，支持单SKU全部或部分件数
-      description: 权限 platform:overseas-warehouse:outbound:create；单SKU来源须为纯SKU可用箱或散件。混合SKU箱须先拆箱。按箱唛排序分配件数，未拣货前占用整个使用来源；拣货后原箱余数恢复可用。相同幂等键改数量拒绝。
+      description: 权限 platform:overseas-warehouse:outbound:create；单SKU来源仅允许PARCEL散件可用库存，不包含箱内库存；实体箱按箱或托盘出库。按散件来源排序分配件数，未拣货前占用整个使用来源；拣货后来源余数恢复可用。相同幂等键改数量拒绝。
       security: [{ bearerAuth: [] }]
       parameters: [{ name: customerId, in: query, required: true, schema: { type: string } }]
       requestBody:
diff --git a/lastleg-service/src/test/java/com/baiyue/lastleg/delivery/service/DeliveryTransferServiceTest.java b/lastleg-service/src/test/java/com/baiyue/lastleg/delivery/service/DeliveryTransferServiceTest.java
index c75ff3859..c4b186925 100644
--- a/lastleg-service/src/test/java/com/baiyue/lastleg/delivery/service/DeliveryTransferServiceTest.java
+++ b/lastleg-service/src/test/java/com/baiyue/lastleg/delivery/service/DeliveryTransferServiceTest.java
@@ -240,6 +240,7 @@ class DeliveryTransferServiceTest {
     void partialSkuOutboundDistributesSixPiecesAcrossTwoFivePieceSources() {
         var first = returnCarton("RC-1", null); first.setId(901L); first.setTotalQuantity(5L);
         var second = returnCarton("RC-2", null); second.setId(902L); second.setTotalQuantity(5L);
+        first.setSourceUnitType("PARCEL"); second.setSourceUnitType("PARCEL");
         when(returnCartons.lockMark("RC-1")).thenReturn(first); when(returnCartons.lockMark("RC-2")).thenReturn(second);
         var line = new ReturnInventoryCartonItem(); line.setSkuCode("SKU-A"); line.setQuantity(5L);
         when(returnCartonItems.lockCarton(901L)).thenReturn(List.of(line));
@@ -252,25 +253,22 @@ class DeliveryTransferServiceTest {
     }
 
     @Test
-    void singleSkuReturnOutboundAcceptsPackedSingleSkuButKeepsCartonScanning() {
+    void singleSkuReturnOutboundRejectsPackedSingleSkuWithoutReservingInventory() {
         ReturnInventoryCarton carton = returnCarton("RC-BOX", "PAL-1");
         carton.setSourceUnitType("BOX"); carton.setTotalQuantity(5L);
-        ReturnInventoryCartonItem line = new ReturnInventoryCartonItem();
-        line.setSkuCode("SKU-A"); line.setQuantity(5L);
         when(returnCartons.lockMark("RC-BOX")).thenReturn(carton);
-        when(returnCartonItems.lockCarton(carton.getId())).thenReturn(List.of(line));
-        service.createReturnOutbound("TENANT-A", "U-1",
-            new DeliveryRequests.ReturnOutbound("receiver", "WH-1", "RT-1", List.of("RC-BOX"), null, "packed-sku", "SKU-A"));
-        ArgumentCaptor<OutboundPalletItem> item = ArgumentCaptor.forClass(OutboundPalletItem.class);
-        verify(outboundPallets).insert(item.capture());
-        assertNull(item.getValue().getSkuCode());
-        assertEquals("RC-BOX", item.getValue().getCartonMarks());
-        assertEquals("OUTBOUND_PENDING", carton.getStatus());
+        var error = assertThrows(ResponseStatusException.class, () -> service.createReturnOutbound("TENANT-A", "U-1",
+            new DeliveryRequests.ReturnOutbound("receiver", "WH-1", "RT-1", List.of("RC-BOX"), null, "packed-sku", "SKU-A")));
+        assertTrue(error.getReason().contains("单SKU出库只允许散件库存"));
+        verify(outboundOrders, never()).insert(any(OutboundOrder.class));
+        verify(returnCartons, never()).updateById(any(ReturnInventoryCarton.class));
+        assertEquals("AVAILABLE", carton.getStatus());
     }
 
     @Test
     void singleSkuReturnOutboundRejectsMixedCarton() {
         ReturnInventoryCarton mixed = returnCarton("RC-MIXED", null);
+        mixed.setSourceUnitType("PARCEL");
         mixed.setId(901L); mixed.setTotalQuantity(5L);
         ReturnInventoryCartonItem skuA = new ReturnInventoryCartonItem(); skuA.setSkuCode("SKU-A"); skuA.setQuantity(3L);
         ReturnInventoryCartonItem skuB = new ReturnInventoryCartonItem(); skuB.setSkuCode("SKU-B"); skuB.setQuantity(2L);