fix(frontend): MetricCards格式化null-safe—退化指标NaN→null不再崩toFixed(显'—')

frontend/src/components/backtest/MetricCards.vue

@@ -2,34 +2,40 @@
 import { computed } from 'vue'
 
 interface RelativeMetrics {
-  total_return: number
-  annual_return: number
-  alpha: number
-  beta: number
-  sharpe_ratio: number
-  sortino_ratio: number
-  information_ratio: number
-  annual_volatility: number
-  max_drawdown: number
-  benchmark_return: number
-  benchmark_volatility: number
+  total_return: number | null
+  annual_return: number | null
+  alpha: number | null
+  beta: number | null
+  sharpe_ratio: number | null
+  sortino_ratio: number | null
+  information_ratio: number | null
+  annual_volatility: number | null
+  max_drawdown: number | null
+  benchmark_return: number | null
+  benchmark_volatility: number | null
 }
 
 const props = defineProps<{ metrics: RelativeMetrics }>()
 
+// null/NaN 安全格式化（后端 NaN→None，退化指标如 sortino 可能为 null）
+function fmt(value: number | null | undefined, digits: number, percent = false): string {
+  if (value == null || isNaN(value as number)) return '—'
+  return percent ? `${(value * 100).toFixed(digits)}%` : value.toFixed(digits)
+}
+
 // 格式化百分比（×100，保留2位小数）
-function formatPercent(value: number): string {
-  return `${(value * 100).toFixed(2)}%`
+function formatPercent(value: number | null): string {
+  return fmt(value, 2, true)
 }
 
 // 格式化小数（保留3位小数）
-function formatDecimal(value: number): string {
-  return value.toFixed(3)
+function formatDecimal(value: number | null): string {
+  return fmt(value, 3)
 }
 
 // 格式化Sharpe等比率（保留2位小数）
-function formatRatio(value: number): string {
-  return value.toFixed(2)
+function formatRatio(value: number | null): string {
+  return fmt(value, 2)
 }
 
 const metricCards = computed(() => [