refine Semi UI alert disposition

vehicle-data-platform/apps/web/src/v2/domain/alert.test.ts

@@ -1,11 +1,17 @@
 import { describe, expect, it } from 'vitest';
-import { alertValue, canAct, formatAlertTime, ruleCondition, thresholdText } from './alert';
+import { alertDeltaText, alertValue, canAct, formatAlertTime, ruleCondition, thresholdText } from './alert';
 
 describe('alert domain helpers', () => {
   it('keeps trigger evidence and duration explicit', () => {
     const event = { triggerValue: 96, threshold: 80, thresholdHigh: 0, operator: 'gt', unit: 'km/h', durationSec: 60 };
     expect(alertValue(event)).toBe('96 km/h');
     expect(thresholdText(event)).toBe('> 80 km/h，持续 60 秒');
+    expect(alertDeltaText(event)).toBe('+16 km/h');
+  });
+
+  it('describes low-bound and non-numeric trigger outcomes without inventing a delta', () => {
+    expect(alertDeltaText({ triggerValue: 12, threshold: 20, operator: 'lt', unit: '%' })).toBe('+8 %');
+    expect(alertDeltaText({ triggerValue: 1, threshold: 1, operator: 'changed', unit: '' })).toBe('规则已命中');
   });
 
   it('enforces valid workflow transitions', () => {

vehicle-data-platform/apps/web/src/v2/domain/alert.ts

@@ -35,6 +35,17 @@ export function thresholdText(event: Pick<AlertEvent, 'operator' | 'threshold' |
   return `${operatorLabels[event.operator] ?? event.operator} ${formatZhNumber(Number(event.threshold.toFixed(2)), 2)} ${event.unit}${duration}`.trim();
 }
 
+export function alertDeltaText(event: Pick<AlertEvent, 'operator' | 'triggerValue' | 'threshold' | 'unit'>) {
+  if (!Number.isFinite(event.triggerValue) || !Number.isFinite(event.threshold)) return '规则已命中';
+  const delta = event.operator === 'gt' || event.operator === 'gte'
+    ? event.triggerValue - event.threshold
+    : event.operator === 'lt' || event.operator === 'lte'
+      ? event.threshold - event.triggerValue
+      : Number.NaN;
+  if (!Number.isFinite(delta)) return '规则已命中';
+  return `+${formatZhNumber(Number(Math.max(0, delta).toFixed(2)), 2)} ${event.unit}`.trim();
+}
+
 export function ruleCondition(rule: AlertRule, labels: Record<string, string> = metricLabels) {
   const threshold = rule.operator === 'changed' ? '状态变化' : rule.operator === 'between' || rule.operator === 'outside' ? `${operatorLabels[rule.operator]} ${rule.threshold}–${rule.thresholdHigh}` : rule.valueType === 'boolean' ? (rule.booleanThreshold ? '是' : '否') : `${operatorLabels[rule.operator] ?? rule.operator} ${rule.threshold}`;
   return `${labels[rule.metric] ?? rule.metric} ${threshold}${rule.durationSec ? ` · ${rule.durationSec} 秒` : ''}`;