diff --git a/klp-ui/src/views/cost/trend.vue b/klp-ui/src/views/cost/trend.vue
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+++ b/klp-ui/src/views/cost/trend.vue
@@ -0,0 +1,488 @@
+<template>
+  <div class="app-container cost-trend-page">
+    <!-- 筛选区 -->
+    <el-card class="mb8">
+      <div class="filter-bar">
+        <el-radio-group
+          v-model="selectedLine"
+          size="small"
+          @change="onLineChange"
+        >
+          <el-radio-button
+            v-for="line in productionLines"
+            :key="line.lineId"
+            :label="line.lineId"
+          >
+            {{ line.lineName }}
+          </el-radio-button>
+        </el-radio-group>
+
+        <el-button type="primary" size="small" icon="el-icon-search" :loading="loading" @click="fetchData">
+          查询
+        </el-button>
+      </div>
+    </el-card>
+
+    <!-- 统计摘要 -->
+    <div v-if="reports.length > 0" class="stats-row">
+      <div class="stat-item stat-blue">
+        <span class="stat-val">{{ reports.length }}</span>
+        <span class="stat-label">参与报表数</span>
+      </div>
+      <div class="stat-item stat-orange">
+        <span class="stat-val">{{ summary.seriesCount }}</span>
+        <span class="stat-label">趋势线数</span>
+      </div>
+      <div class="stat-item stat-green">
+        <span class="stat-val">{{ summary.maxLabel }}</span>
+        <span class="stat-label">单报表最高数量</span>
+      </div>
+    </div>
+
+    <!-- 图表筛选 -->
+    <div v-if="reports.length > 0" class="chart-filter-bar">
+      <span class="filter-label">图表筛选：</span>
+      <el-select
+        v-model="selectedCategories"
+        multiple
+        collapse-tags
+        placeholder="成本类别（全部）"
+        size="small"
+        style="width:160px"
+        @change="onCategoryChange"
+        clearable
+      >
+        <el-option label="原料" value="原料" />
+        <el-option label="能耗" value="能耗" />
+        <el-option label="辅料" value="辅料" />
+        <el-option label="设备" value="设备" />
+        <el-option label="人工" value="人工" />
+        <el-option label="产出" value="产出" />
+        <el-option label="轧辊" value="轧辊" />
+        <el-option label="其他" value="其他" />
+      </el-select>
+      <el-select
+        v-model="selectedItems"
+        multiple
+        collapse-tags
+        filterable
+        placeholder="成本项（全部）"
+        size="small"
+        style="width:220px"
+        @change="onItemChange"
+        clearable
+      >
+        <el-option
+          v-for="it in filteredItemOptions"
+          :key="it.itemId"
+          :label="it.itemName + ' (' + it.category + ')'"
+          :value="it.itemId"
+        />
+      </el-select>
+    </div>
+
+    <!-- 图表区 -->
+    <div class="chart-box" v-loading="loading">
+      <div ref="trendChart" class="chart-body" />
+    </div>
+
+    <div v-if="summary.seriesCount > 15" class="legend-hint">
+      <i class="el-icon-info" /> 图例较多，可在下方图例区滚动查看，或缩小筛选范围以减少趋势线数量
+    </div>
+  </div>
+</template>
+
+<script>
+import * as echarts from 'echarts'
+import { mapGetters } from 'vuex'
+import { listProdReport } from '@/api/cost/prodReport'
+import { listProdDetail } from '@/api/cost/prodDetail'
+import { listItem } from '@/api/cost/item'
+
+const COLORS = [
+  '#409eff', '#67c23a', '#e6a23c', '#f56c6c', '#909399',
+  '#9b59b6', '#1abc9c', '#e74c3c', '#3498db', '#2ecc71',
+  '#f39c12', '#e91e63', '#00bcd4', '#8bc34a', '#ff5722',
+  '#607d8b', '#3f51b5', '#cddc39', '#ff9800', '#795548',
+  '#2196f3', '#4caf50', '#ffc107', '#9c27b0', '#00bcd4'
+]
+
+export default {
+  name: 'CostTrend',
+  data() {
+    return {
+      selectedLine: null,
+      selectedCategories: [],
+      selectedItems: [],
+      allItems: [],
+      loading: false,
+      chart: null,
+      reports: [],
+      cachedDetails: [],
+      summary: { seriesCount: 0, maxLabel: '-' }
+    }
+  },
+  computed: {
+    ...mapGetters(['productionLines']),
+    selectedLineObj() {
+      if (!this.selectedLine || !this.productionLines.length) return null
+      return this.productionLines.find(l => l.lineId === this.selectedLine) || null
+    },
+    lineNameDisplay() {
+      const line = this.selectedLineObj
+      return line ? line.lineName : ''
+    },
+    filteredItemOptions() {
+      if (!this.selectedCategories.length) return this.allItems
+      return this.allItems.filter(it => this.selectedCategories.includes(it.category))
+    }
+  },
+  mounted() {
+    this.$store.dispatch('productionLine/getProductionLines').then(() => {
+      this.initDefaultLine()
+      this.$nextTick(() => this.fetchData())
+    })
+    this.loadItems()
+    this._resizeHandler = () => { if (this.chart) this.chart.resize() }
+    window.addEventListener('resize', this._resizeHandler)
+  },
+  beforeDestroy() {
+    window.removeEventListener('resize', this._resizeHandler)
+    if (this.chart) { this.chart.dispose(); this.chart = null }
+  },
+  methods: {
+    initDefaultLine() {
+      if (this.selectedLine != null) return
+      const lines = this.productionLines || []
+      const dzLine = lines.find(l => l.lineName && l.lineName.includes('镀锌'))
+      if (dzLine) {
+        this.selectedLine = dzLine.lineId
+      } else if (lines.length) {
+        this.selectedLine = lines[0].lineId
+      }
+    },
+
+    onLineChange() {
+      if (this.selectedLine != null) {
+        this.fetchData()
+      }
+    },
+
+    onCategoryChange() {
+      this.selectedItems = this.selectedItems.filter(id => {
+        const it = this.allItems.find(item => item.itemId === id)
+        return it && this.selectedCategories.includes(it.category)
+      })
+      this.renderFromCache()
+    },
+
+    onItemChange() {
+      this.renderFromCache()
+    },
+
+    async loadItems() {
+      try {
+        const r = await listItem({ pageNum: 1, pageSize: 999 })
+        this.allItems = r.rows || []
+      } catch (e) { /* ignore */ }
+    },
+    
+    async fetchData() {
+      if (this.selectedLine == null) {
+        return
+      }
+
+      this.loading = true
+      try {
+        const params = {
+          lineType: this.selectedLine,
+          pageNum: 1,
+          pageSize: 999
+        }
+
+        const reportRes = await listProdReport(params)
+        const allReports = (reportRes.rows || []).sort((a, b) => {
+          return (a.reportDate || '').localeCompare(b.reportDate || '')
+        })
+        console.log('[CostTrend] reports:', allReports.length, allReports.map(r => ({ id: r.reportId, title: r.reportTitle, date: r.reportDate })))
+
+        if (!allReports.length) {
+          this.$modal.msgWarning('该产线暂无报表')
+          this.reports = []
+          this.summary = { seriesCount: 0, maxLabel: '-' }
+          if (this.chart) this.chart.clear()
+          return
+        }
+        this.reports = allReports
+
+        await this.fetchDetailsAndCache(allReports)
+      } catch (e) {
+        console.error('CostTrend fetchData error:', e)
+        this.$modal.msgError('数据加载失败: ' + (e.message || '未知错误'))
+      } finally {
+        this.loading = false
+      }
+    },
+
+    // ==================== 成本项模式 ====================
+    async fetchDetailsAndCache(reports) {
+      const allDetailResults = await Promise.all(
+        reports.map(r =>
+          listProdDetail({ reportId: r.reportId, pageNum: 1, pageSize: 99999 })
+            .then(res => {
+              console.log('[CostTrend] detail for report', r.reportId, 'rows:', (res.rows || []).length)
+              return { reportId: r.reportId, rows: res.rows || [] }
+            })
+            .catch(e => {
+              console.error('[CostTrend] detail fetch error for report', r.reportId, e)
+              return { reportId: r.reportId, rows: [] }
+            })
+        )
+      )
+      this.cachedDetails = allDetailResults
+
+      if (!this.allItems.length) await this.loadItems()
+
+      this.renderFromCache()
+    },
+
+    renderFromCache() {
+      const reports = this.reports
+      const allDetailResults = this.cachedDetails
+      if (!reports.length || !allDetailResults.length) return
+
+      const itemMap = {}
+      this.allItems.forEach(it => { itemMap[String(it.itemId)] = it })
+
+      const itemSet = this.selectedItems.length ? new Set(this.selectedItems.map(String)) : null
+      const categorySet = this.selectedCategories.length ? new Set(this.selectedCategories) : null
+
+      const reportSums = {}
+      allDetailResults.forEach(({ reportId, rows }) => {
+        const sums = {}
+        rows.forEach(d => {
+          if (!d.itemId) return
+          const key = String(d.itemId)
+          if (itemSet && !itemSet.has(key)) return
+          if (categorySet) {
+            const it = itemMap[key]
+            if (!it || !categorySet.has(it.category)) return
+          }
+          sums[key] = (sums[key] || 0) + (parseFloat(d.quantity) || 0)
+        })
+        reportSums[reportId] = sums
+      })
+
+      const allItemIds = new Set()
+      Object.values(reportSums).forEach(sums => {
+        Object.keys(sums).forEach(id => allItemIds.add(id))
+      })
+
+      const xLabels = reports.map(r => this.reportLabel(r))
+      const series = []
+      let globalMax = 0
+
+      Array.from(allItemIds).forEach((key, idx) => {
+        const it = itemMap[key]
+        const name = it ? it.itemName : `未知(${key})`
+        const data = reports.map(r => {
+          const sums = reportSums[r.reportId] || {}
+          const val = sums[key] ?? null
+          if (val != null && val > globalMax) globalMax = val
+          return val
+        })
+        if (data.every(v => v === null)) return
+
+        series.push({
+          name,
+          type: 'line',
+          data,
+          smooth: true,
+          symbol: 'circle',
+          symbolSize: 6,
+          lineStyle: { width: 2, color: COLORS[idx % COLORS.length] },
+          itemStyle: { color: COLORS[idx % COLORS.length] },
+          emphasis: { focus: 'series' }
+        })
+      })
+
+      this.summary = {
+        seriesCount: series.length,
+        maxLabel: this.formatMoney(globalMax)
+      }
+
+      this.$nextTick(() => {
+        setTimeout(() => this.renderChart(xLabels, series, '数量'), 50)
+      })
+    },
+
+    // ==================== 图表渲染 ====================
+    renderChart(xLabels, series, yAxisName) {
+      console.log('[CostTrend] renderChart called, ref:', !!this.$refs.trendChart, 'series:', series.length, 'xLabels:', xLabels.length)
+      if (!this.$refs.trendChart) return
+      if (this.chart) this.chart.dispose()
+      this.chart = echarts.init(this.$refs.trendChart)
+
+      if (!series.length) {
+        this.chart.setOption({
+          title: { text: '暂无数据', left: 'center', top: 'center', textStyle: { color: '#999', fontSize: 14 } },
+          xAxis: { show: false },
+          yAxis: { show: false },
+          series: []
+        })
+        return
+      }
+
+      this.chart.setOption({
+        tooltip: {
+          trigger: 'axis',
+          formatter: function (params) {
+            if (!params || !params.length) return ''
+            let html = '<b>' + params[0].axisValue + '</b><br/>'
+            params.forEach(p => {
+              if (p.value != null) {
+                html += '<span style="display:inline-block;width:10px;height:10px;border-radius:50%;background:' +
+                  p.color + ';margin-right:5px;"></span>' +
+                  p.seriesName + ': <b>' +
+                  Number(p.value).toLocaleString('zh-CN', { minimumFractionDigits: 2, maximumFractionDigits: 2 }) +
+                  '</b><br/>'
+              }
+            })
+            return html
+          }
+        },
+        legend: {
+          type: 'scroll',
+          bottom: 0,
+          textStyle: { fontSize: 11 },
+          pageIconSize: 12,
+          pageTextStyle: { fontSize: 11 }
+        },
+        grid: {
+          left: '3%',
+          right: '4%',
+          top: '3%',
+          bottom: series.length > 20 ? '18%' : (series.length > 10 ? '14%' : '10%'),
+          containLabel: true
+        },
+        xAxis: {
+          type: 'category',
+          data: xLabels,
+          boundaryGap: false,
+          axisLabel: {
+            fontSize: 11,
+            rotate: xLabels.length > 8 ? 30 : 0
+          }
+        },
+        yAxis: {
+          type: 'value',
+          name: yAxisName,
+          axisLabel: {
+            fontSize: 11,
+            formatter: function (v) {
+              if (v >= 10000) return (v / 10000).toFixed(1) + '万'
+              return v
+            }
+          },
+          splitLine: { lineStyle: { type: 'dashed', color: '#e8e8e8' } }
+        },
+        dataZoom: xLabels.length > 10 ? [
+          {
+            type: 'slider',
+            bottom: series.length > 10 ? (series.length > 20 ? 60 : 50) : 35,
+            height: 16,
+            textStyle: { fontSize: 10 }
+          },
+          { type: 'inside' }
+        ] : [],
+        series
+      }, true)
+    },
+
+    reportLabel(r) {
+      const date = r.reportDate
+        ? (typeof r.reportDate === 'string' ? r.reportDate.slice(0, 10) : String(r.reportDate).slice(0, 10))
+        : ''
+      return r.reportTitle || date || `报表#${r.reportId}`
+    },
+
+    formatMoney(val) {
+      if (val == null || val === '' || isNaN(val)) return '-'
+      const num = Number(val)
+      if (num >= 10000) return (num / 10000).toFixed(2) + '万'
+      return num.toFixed(2)
+    }
+  }
+}
+</script>
+
+<style scoped>
+.mb8 { margin-bottom: 10px; }
+
+.filter-bar {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  flex-wrap: wrap;
+}
+
+.stats-row {
+  display: flex;
+  gap: 8px;
+  margin-bottom: 10px;
+}
+.stat-item {
+  flex: 1;
+  min-width: 100px;
+  background: #fff;
+  border: 1px solid #ebeef5;
+  border-radius: 2px;
+  padding: 10px 12px;
+  text-align: center;
+}
+.stat-val {
+  display: block;
+  font-size: 22px;
+  font-weight: 600;
+  color: #303133;
+  line-height: 1.2;
+}
+.stat-label {
+  display: block;
+  font-size: 12px;
+  color: #909399;
+  margin-top: 2px;
+}
+.stat-blue .stat-val { color: #409eff; }
+.stat-orange .stat-val { color: #e6a23c; }
+.stat-green .stat-val { color: #67c23a; }
+
+.chart-box {
+  background: #fff;
+  border: 1px solid #ebeef5;
+  border-radius: 2px;
+}
+.chart-filter-bar {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  margin-bottom: 8px;
+}
+.chart-filter-bar .filter-label {
+  font-size: 13px;
+  color: #606266;
+  white-space: nowrap;
+}
+.chart-body {
+  width: 100%;
+  height: 480px;
+}
+.legend-hint {
+  margin-top: 8px;
+  font-size: 12px;
+  color: #909399;
+  display: flex;
+  align-items: center;
+  gap: 4px;
+}
+</style>