feat(purchase): 采购单号改为 批次-批内序号 格式，显式体现同批

按用户原始逻辑还原并扩展:
- 单号格式: PUR-日期-时间-批次-批内序号
  例: PUR-20260831-1021-0001-0001（今日第1次采购的第1条）
- generate_request_no 支持 batch_seq 参数生成批次+批内序号
- 新增 GET /purchase/next-batch-seq 返回今日下一个批次号
- 前端提交时获取批次号，同批所有行共享，循环提交生成连续批内序号
- 批次识别: 单号去掉末尾 -批内序号 即为批次前缀
- 保留旧格式兼容（无 batch_seq 时回退 PUR-日期-时间-流水）

inventory-backend/app/api/v1/purchase.py

@@ -237,6 +237,18 @@ def approve_purchase_request(purchase_id):
 # 5. 获取可选审批人列表
 # GET /api/v1/purchase/approvers
 # --------------------------------------------------------
+@purchase_bp.route('/next-batch-seq', methods=['GET'])
+@jwt_required()
+def get_next_batch_seq():
+    """获取今日下一个采购批次号（前端提交一批时调用，同批所有行共享）"""
+    try:
+        next_seq = PurchaseService.get_next_batch_seq()
+        return jsonify({'code': 200, 'msg': '获取成功', 'data': {'batch_seq': next_seq}}), 200
+    except Exception as e:
+        traceback.print_exc()
+        return jsonify({'code': 500, 'msg': str(e)}), 500
+
+
 @purchase_bp.route('/batch-approve', methods=['POST'])
 @jwt_required()
 @permission_required('inbound_purchase:operation')

inventory-backend/app/services/purchase_service.py

@@ -9,16 +9,58 @@ from app.models.base import MaterialBase
 class PurchaseService:
 
     @staticmethod
-    def generate_request_no():
-        """生成采购单号: PUR-yyyyMMdd-HHmm-当日流水(4位)"""
+    def generate_request_no(batch_seq: int = None):
+        """
+        生成采购单号: PUR-yyyyMMdd-HHmm-批次-批内序号
+
+        Args:
+            batch_seq: 今日第几次采购批次（前端提交一批时传入，同一批共享）
+                       None 时回退为旧格式 PUR-日期-时间-流水
+
+        返回:
+            - 有 batch_seq: PUR-20260831-1021-0001-0001（批次号-批内序号）
+            - 无 batch_seq: PUR-20260831-1021-0001（旧格式兼容）
+        """
+        beijing_tz = timezone(timedelta(hours=8))
+        now = datetime.now(beijing_tz)
+        date_str = now.strftime('%Y%m%d')
+        time_str = now.strftime('%H%M')
+
+        if batch_seq is not None:
+            # 批次前缀: PUR-日期-时间-批次
+            batch_prefix = f"PUR-{date_str}-{time_str}-{batch_seq:04d}"
+            # 批内序号: 该批次前缀下的记录数 + 1
+            item_count = db.session.query(func.count(func.distinct(PurchaseRequest.request_no))) \
+                .filter(PurchaseRequest.request_no.like(f"{batch_prefix}-%")).scalar()
+            return f"{batch_prefix}-{(item_count + 1):04d}"
+
+        # 旧格式兼容: PUR-日期-时间-流水
+        prefix = f"PUR-{date_str}-{time_str}-"
+        existing_count = db.session.query(func.count(func.distinct(PurchaseRequest.request_no))) \
+            .filter(PurchaseRequest.request_no.like(f"{prefix}%")).scalar()
+        return f"{prefix}{(existing_count + 1):04d}"
+
+    @staticmethod
+    def get_next_batch_seq():
+        """
+        返回今日下一个采购批次号（今日第几次）
+        统计今日已有的不同批次（单号第4段）数量，+1
+        """
         beijing_tz = timezone(timedelta(hours=8))
         now = datetime.now(beijing_tz)
         date_str = now.strftime('%Y%m%d')
         time_str = now.strftime('%H%M')
         prefix = f"PUR-{date_str}-{time_str}-"
-        existing_count = db.session.query(func.count(func.distinct(PurchaseRequest.request_no))) \
-            .filter(PurchaseRequest.request_no.like(f"{prefix}%")).scalar()
-        return f"{prefix}{(existing_count + 1):04d}"
+
+        # 查询今日所有单号，提取第4段（批次号）去重
+        rows = db.session.query(PurchaseRequest.request_no) \
+            .filter(PurchaseRequest.request_no.like(f"{prefix}%")).all()
+        batch_seqs = set()
+        for (rn,) in rows:
+            parts = rn.split('-')
+            if len(parts) >= 4:
+                batch_seqs.add(parts[3])
+        return len(batch_seqs) + 1
 
     @staticmethod
     def auto_fill_from_material(keyword: str):
@@ -47,7 +89,8 @@ class PurchaseService:
         data 包含: name, spec_model, quantity, purchase_date, supplier_link, remark, images,
                   unit_price, total_price, approver_id, base_id (可选)
         """
-        request_no = PurchaseService.generate_request_no()
+        batch_seq = data.get('batch_seq')
+        request_no = PurchaseService.generate_request_no(batch_seq=batch_seq)
 
         purchase_date = data.get('purchase_date')
         if isinstance(purchase_date, str):

inventory-web/src/api/purchase.ts

@@ -109,6 +109,14 @@ export function getPurchaseByBatch(batchKey: string) {
   })
 }
 
+// 获取今日下一个采购批次号（提交一批时调用，同批所有行共享）
+export function getNextBatchSeq() {
+  return request({
+    url: '/purchase/next-batch-seq',
+    method: 'get'
+  })
+}
+
 // 获取可选审批人列表
 export function getPurchaseApprovers() {
   return request({

inventory-web/src/views/purchase/index.vue

@@ -362,7 +362,7 @@ import { searchMaterialPurchase } from '@/api/purchase'
 import {
   getPurchaseList, createPurchase, getPurchaseDetail,
   approvePurchase, batchApprovePurchase, getPurchaseApprovers, autoFillPurchase,
-  getPurchaseByBatch
+  getPurchaseByBatch, getNextBatchSeq
 } from '@/api/purchase'
 import { uploadFile, deleteFile } from '@/api/common/upload'
 import type { FormInstance } from 'element-plus'
@@ -951,12 +951,21 @@ const submitForm = async () => {
     }
   }
 
-  // 3. 逐行提交（每行携带公共信息）
+  // 3. 逐行提交（每行携带公共信息 + 同一批次号）
   submitLoading.value = true
   let successCount = 0
+  // ★ 获取今日批次号：同一批所有行共享，单号体现 PUR-日期-时间-批次-批内序号
+  let batchSeq: number | undefined
+  try {
+    const seqRes: any = await getNextBatchSeq()
+    batchSeq = seqRes.data?.batch_seq
+  } catch (e) {
+    // 获取批次号失败不阻断，回退旧格式
+  }
   try {
     for (const row of validItems) {
       const payload: any = {
+        batch_seq: batchSeq,
         name: row.name,
         spec_model: row.spec_model,
         quantity: row.quantity,