fix(kpi): 阈值红黄绿读写/填写规则修复 — 统一解析器+红灯优先+建议可解析+前端校验+存量修正 (project-20260911-threshold-fix)

① 新建 app/utils/threshold_parser.py 统一解析/判定（单一事实源）：
   - 支持负数（>=-100000）、闭区间 A~B、多条件 C1|C2；空串=未设置
   - 判定顺序 red→green→yellow：红灯优先（消除宽黄灯遮蔽红灯），
     green 先于 yellow（green 是主条件，yellow 是更宽兜底带）
② kpis.py / alert_generator.py 双实现收敛到统一解析器（消除重复维护）
③ thresholds.py suggest 输出可解析表达式（原黄色/适中型生成 `52.33~107.67`、`偏离55%` 等
   区间/文字 → 用户点"自动建议"填入后静默失效；另修复大数目标生成 1.6e+06 科学计数法）
④ KPIDetail.vue 三个阈值输入加 placeholder/tooltip/帮助文案 + 保存前格式校验（非法即拒）
⑤ 存量 4 个不可解析表达式修正（id=46 C_REBATE_RATE / id=327 BH_SALES_10），
   改前 mysqldump 备份 backend/scripts/backups/kpi_definitions.bak-20260911.sql +
   threshold_rows_before_20260911.json（可回滚）；不可解析 5→0
⑥ 单测 97 条 + 红黄绿判定回归 367 判定点（旧→新差异 14 条，含差异说明）

frontend/src/views/KPIDetail.vue

@@ -128,11 +128,37 @@
                     <el-button size="small" type="primary" plain @click="associateMap">关联</el-button>
                   </div>
                 </el-form-item>
-                <el-form-item label="绿灯阈值">
-                  <div style="display:flex;gap:8px;"><el-input v-model="kpi.threshold_green" /><el-button size="small" type="primary" plain @click="suggestThreshold">自动建议</el-button></div>
+                <el-form-item>
+                  <template #label>
+                    绿灯阈值
+                    <el-tooltip :content="THRESHOLD_HELP_TEXT" placement="top">
+                      <el-icon style="margin-left:4px;vertical-align:-2px;cursor:help;color:#909399;"><QuestionFilled /></el-icon>
+                    </el-tooltip>
+                  </template>
+                  <div style="display:flex;gap:8px;width:100%;">
+                    <el-input v-model="kpi.threshold_green" placeholder="如 >=800 / 52.33~107.67" clearable style="width:100%" />
+                    <el-button size="small" type="primary" plain @click="suggestThreshold">自动建议</el-button>
+                  </div>
                 </el-form-item>
-                <el-form-item label="黄灯阈值"><el-input v-model="kpi.threshold_yellow" /></el-form-item>
-                <el-form-item label="红灯阈值"><el-input v-model="kpi.threshold_red" /></el-form-item>
+                <el-form-item>
+                  <template #label>
+                    黄灯阈值
+                    <el-tooltip :content="THRESHOLD_HELP_TEXT" placement="top">
+                      <el-icon style="margin-left:4px;vertical-align:-2px;cursor:help;color:#909399;"><QuestionFilled /></el-icon>
+                    </el-tooltip>
+                  </template>
+                  <el-input v-model="kpi.threshold_yellow" placeholder="如 >=800 / 52.33~107.67" clearable style="width:100%" />
+                </el-form-item>
+                <el-form-item>
+                  <template #label>
+                    红灯阈值
+                    <el-tooltip :content="THRESHOLD_HELP_TEXT" placement="top">
+                      <el-icon style="margin-left:4px;vertical-align:-2px;cursor:help;color:#909399;"><QuestionFilled /></el-icon>
+                    </el-tooltip>
+                  </template>
+                  <el-input v-model="kpi.threshold_red" placeholder="如 >=800 / 52.33~107.67" clearable style="width:100%" />
+                </el-form-item>
+                <div style="color:#909399;font-size:12px;line-height:1.5;margin-top:-6px;">{{ THRESHOLD_HELP_TEXT }}</div>
               </el-col>
             </el-row>
             <el-row>
@@ -354,6 +380,7 @@
 import { ref, onMounted, computed, watch } from 'vue'
 import { useRoute } from 'vue-router'
 import { ElMessage } from 'element-plus'
+import { QuestionFilled } from '@element-plus/icons-vue'
 import VChart from 'vue-echarts'
 import 'echarts'
 import { kpiApi, mapApi, kpiCausalityApi, orgApi, userApi } from '../api/index'
@@ -737,8 +764,23 @@ const fullNetworkChartOption = computed(() => {
   }
 })
 
+// 阈值语法与后端 app/utils/threshold_parser.py 保持一致
+const THRESHOLD_CLAUSE_RE = /^(?:-?\d+(?:\.\d+)?\s*~\s*-?\d+(?:\.\d+)?|(?:>=|<=|!=|>|<|=)\s*-?\d+(?:\.\d+)?)$/
+const THRESHOLD_HELP_TEXT = '支持格式：>=800 / <=25 / >60 / <20 / =100 / !=0（数值可为负数，如 <-100000）；区间 52.33~107.67（含端点）；多条件用 | 连接，如 <=36|>=124。'
+function isValidThreshold(v: any): boolean {
+  const s = String(v ?? '').trim()
+  if (!s) return true
+  return s.split(/[|｜]/).every(c => THRESHOLD_CLAUSE_RE.test(c.trim()))
+}
+
 async function save() {
   if (saving.value) return
+  const invalid = ([['绿灯阈值', kpi.value.threshold_green], ['黄灯阈值', kpi.value.threshold_yellow], ['红灯阈值', kpi.value.threshold_red]] as [string, any][])
+    .filter(([, v]) => !isValidThreshold(v))
+  if (invalid.length) {
+    ElMessage.error(`${invalid.map(([n]) => n).join('、')}格式非法；${THRESHOLD_HELP_TEXT}`)
+    return
+  }
   saving.value = true
   try {
     // 多粒度目标同步：按frequency将对应周期目标写入target_value(兼容评分/阈值等旧逻辑)
@@ -767,10 +809,18 @@ async function suggestThreshold() {
     const r: any = await api.get('/thresholds/suggest/' + kpi.value.id)
     const s = r.suggestion
     if (!s) { ElMessage.warning('暂无建议数据'); return }
-    kpi.value.threshold_green = s.green?.label || ''
-    kpi.value.threshold_yellow = s.yellow?.label || ''
-    kpi.value.threshold_red = s.red?.label || ''
-    ElMessage.success('已自动填入推荐阈值')
+    const g = s.green?.label || ''
+    const y = s.yellow?.label || ''
+    const rd = s.red?.label || ''
+    // 建议值必须自身可解析（防填入不可解析格式 → 静默失效）
+    if (!isValidThreshold(g) || !isValidThreshold(y) || !isValidThreshold(rd)) {
+      ElMessage.error('自动建议生成值格式非法，请检查后端 suggest 接口')
+      return
+    }
+    kpi.value.threshold_green = g
+    kpi.value.threshold_yellow = y
+    kpi.value.threshold_red = rd
+    ElMessage.success('已自动填入推荐阈值（格式已校验）')
   } catch (e) {
     ElMessage.error('获取阈值建议失败')
   }
@@ -900,6 +950,7 @@ function onMapChange(val: any) {}
 .kpi-detail-page .header-card .header-title { font-size: 16px; font-weight: 600; }
 .kpi-detail-page .header-card .header-tag { margin-left: 8px; }
 .kpi-detail-page .header-card .header-tag-gap { margin-left: 4px; }
+.threshold-help { cursor: help; color: #909399; font-size: 12px; line-height: 28px; white-space: nowrap; }
 .full-width-chart { height: 300px; width: 100%; }
 .data-table { width: 100%; margin-top: 12px; }
 .network-empty { color: #999; text-align: center; padding: 20px; }