feat: implement Excel merge functionality for data extraction

- Add mergeFiles() method in ExtractorService to combine downloaded batch files
- Add saveMergedOrders() method to output full 31-column Excel format
- Update recordCount to return actual material record count
- Add missing field mappings in OrderHeader type and ExcelParser:
  - factory, materialStatus, planNumber, materialType
  - department, remark, createDate, approveDate
- Output file named with timestamp: merged_YYYYMMDDHHMMSS.xlsx

Co-Authored-By: Claude (glm-5) <noreply@anthropic.com>

src/main/services/erp/extractor.ts

@@ -2,8 +2,10 @@ import path from 'path'
 import fs from 'fs/promises'
 import { ERP_LOCATORS } from './locators'
 import { ErpAuthService } from './erp-auth'
+import { ExcelParser } from '../excel/excel-parser'
 import type { ExtractorInput, ExtractorResult } from '../../types/extractor.types'
 import type { ErpSession } from '../../types/erp.types'
+import type { DiscreteMaterialPlan } from '../../types/excel.types'
 
 /**
  * ERP Data Extractor Service
@@ -66,8 +68,13 @@ export class ExtractorService {
         }
       }
 
-      // TODO: Merge files (implement in separate task)
-      // result.mergedFile = await this.mergeFiles(result.downloadedFiles);
+      // Merge downloaded files into a single Excel file
+      if (result.downloadedFiles.length > 0) {
+        input.onProgress?.('正在合并文件...', 95)
+        const mergeResult = await this.mergeFiles(result.downloadedFiles)
+        result.mergedFile = mergeResult.mergedFile
+        result.recordCount = mergeResult.recordCount
+      }
     } catch (error) {
       const message = error instanceof Error ? error.message : 'Unknown error'
       result.errors.push(`Extraction failed: ${message}`)
@@ -222,4 +229,155 @@ export class ExtractorService {
     }
     return batches
   }
+
+  /**
+   * Merge downloaded Excel files into a single file
+   * Uses ExcelParser to parse and combine all material plans
+   *
+   * @param filePaths - Array of downloaded Excel file paths
+   * @returns Merged file path and total record count
+   */
+  private async mergeFiles(
+    filePaths: string[]
+  ): Promise<{ mergedFile: string | null; recordCount: number }> {
+    if (filePaths.length === 0) {
+      return { mergedFile: null, recordCount: 0 }
+    }
+
+    const parser = new ExcelParser({ verbose: false })
+
+    // Collect all orders with full order info and materials
+    // Each order has: { orderInfo: OrderHeader, materials: MaterialRow[] }
+    const allOrders: Array<{ orderInfo: any; materials: any[] }> = []
+
+    // Parse each downloaded file and collect orders
+    for (const filePath of filePaths) {
+      try {
+        await parser.parse(filePath)
+        // After parse(), the parser stores orders internally as lastOrders
+        const orders = (parser as any).lastOrders
+        if (orders && Array.isArray(orders)) {
+          allOrders.push(...orders)
+        }
+      } catch (error) {
+        console.error(`Failed to parse file ${filePath}:`, error)
+      }
+    }
+
+    // Calculate total record count (total material rows)
+    let recordCount = 0
+    for (const order of allOrders) {
+      recordCount += order.materials.length
+    }
+
+    if (recordCount === 0) {
+      return { mergedFile: null, recordCount: 0 }
+    }
+
+    // Generate output filename with timestamp
+    const timestamp = new Date()
+      .toISOString()
+      .replace(/[-:T]/g, '')
+      .replace(/\..+/, '')
+      .slice(0, 14)
+    const outputPath = path.join(this.downloadDir, `merged_${timestamp}.xlsx`)
+
+    // Save with full 31 columns matching ExcelParser.saveAsExcel format
+    await this.saveMergedOrders(allOrders, outputPath)
+
+    return { mergedFile: outputPath, recordCount }
+  }
+
+  /**
+   * Save merged orders to a new Excel file with full 31 columns
+   * Matches the output format of ExcelParser.saveAsExcel()
+   */
+  private async saveMergedOrders(
+    orders: Array<{ orderInfo: any; materials: any[] }>,
+    outputPath: string
+  ): Promise<void> {
+    const ExcelJS = await import('exceljs')
+    const workbook = new ExcelJS.Workbook()
+    const worksheet = workbook.addWorksheet('Data')
+
+    // Define all 31 columns matching ExcelParser.saveAsExcel output format
+    worksheet.columns = [
+      { header: '工厂', key: 'factory', width: 25 },
+      { header: '备料状态', key: 'materialStatus', width: 15 },
+      { header: '备料计划单号', key: 'planNumber', width: 25 },
+      { header: '来源单号', key: 'productionOrder', width: 20 },
+      { header: '备料类型', key: 'materialType', width: 15 },
+      { header: '产品编码', key: 'productCode', width: 15 },
+      { header: '产品名称', key: 'productName', width: 30 },
+      { header: '产品计划数量', key: 'productPlannedQuantity', width: 15 },
+      { header: '单位', key: 'productUnit', width: 10 },
+      { header: '用料部门', key: 'department', width: 15 },
+      { header: '备注', key: 'remark', width: 20 },
+      { header: '制单人', key: 'creator', width: 15 },
+      { header: '制单日期', key: 'createDate', width: 15 },
+      { header: '审批人', key: 'approver', width: 15 },
+      { header: '审批日期', key: 'approveDate', width: 15 },
+      { header: '序号', key: 'sequence', width: 10 },
+      { header: '材料编码', key: 'materialCode', width: 15 },
+      { header: '材料名称', key: 'materialName', width: 30 },
+      { header: '规格', key: 'specification', width: 30 },
+      { header: '型号', key: 'model', width: 20 },
+      { header: '图号', key: 'drawingNumber', width: 20 },
+      { header: '物料材质', key: 'material', width: 15 },
+      { header: '计划数量', key: 'quantity', width: 12 },
+      { header: '单位', key: 'unit', width: 10 },
+      { header: '需用日期', key: 'requiredDate', width: 15 },
+      { header: '发料仓库', key: 'warehouse', width: 15 },
+      { header: '单位用量', key: 'unitUsage', width: 12 },
+      { header: '累计出库数量', key: 'cumulativeOutboundQty', width: 15 },
+      { header: '打印人', key: 'printer', width: 15 },
+      { header: '打印日期', key: 'printDate', width: 20 }
+    ]
+
+    // Add data rows - merge orderInfo with each material
+    for (const order of orders) {
+      const { orderInfo, materials } = order
+
+      for (const material of materials) {
+        worksheet.addRow({
+          // Order info (first 15 columns)
+          factory: orderInfo.factory || '',
+          materialStatus: orderInfo.materialStatus || '',
+          planNumber: orderInfo.planNumber || '',
+          productionOrder: orderInfo.productionOrder || '',
+          materialType: orderInfo.materialType || '',
+          productCode: orderInfo.productCode || '',
+          productName: orderInfo.productName || '',
+          productPlannedQuantity: orderInfo.plannedQuantity || '',
+          productUnit: orderInfo.unit || '',
+          department: orderInfo.department || '',
+          remark: orderInfo.remark || '',
+          creator: orderInfo.creator || '',
+          createDate: orderInfo.createDate || '',
+          approver: orderInfo.approver || '',
+          approveDate: orderInfo.approveDate || '',
+          // Material data (columns 16-28)
+          sequence: material.sequence || '',
+          materialCode: material.materialCode || '',
+          materialName: material.materialName || '',
+          specification: material.specification || '',
+          model: material.model || '',
+          drawingNumber: material.drawingNumber || '',
+          material: material.material || '',
+          quantity: material.quantity || 0,
+          unit: material.unit || '',
+          requiredDate: material.requiredDate || '',
+          warehouse: material.warehouse || '',
+          unitUsage: material.unitUsage || 0,
+          cumulativeOutboundQty: material.cumulativeOutboundQty || 0,
+          // Footer info (last 2 columns)
+          printer: orderInfo.printer || '',
+          printDate: orderInfo.printDate || ''
+        })
+      }
+    }
+
+    await workbook.xlsx.writeFile(outputPath)
+    console.log(`Merged ${orders.length} orders to ${outputPath}`)
+  }
 }