feat(frontend): 首页指标卡与项目行 sparkline（前端重设计第二轮之一）

[变更性质] 新增能力，不动后端。
[新增功能] dashboardMetrics 聚合（项目/数据集/实验/AI 用量统计 + 最近回测首末净值），实盘数据优先、缺数以占位符 '-' 兜底；ProjectMetricRow 渲染 4 张 metric-card；Sparkline 组件输出 up/down 方向线段与端点圆点。
[实现方案] 聚合逻辑与展示组件分离，sparkline 仅依赖 first/last 两个字段，无图表库依赖。
[影响范围] frontend/src/lib 与 components；配套 5 组单测（dashboardMetrics/sparkline/metricRow）。

1 files changed, 63 insertions, 0 deletions

diff --git a/frontend/src/lib/metricRow.test.ts b/frontend/src/lib/metricRow.test.ts
new file mode 100644
index 0000000..bc41b54
--- /dev/null
+++ b/frontend/src/lib/metricRow.test.ts
@@ -0,0 +1,63 @@
+// @ts-nocheck
+import { describe, expect, it, vi, afterEach } from 'vitest';
+import { cleanup } from '@testing-library/svelte';
+import { render, screen } from '@testing-library/svelte';
+
+import ProjectMetricRow from '../components/ProjectMetricRow.svelte';
+
+// Leader round2: 首页改为指标卡行——当前项目数、数据集总数、
+// 运行中/已完成回测数、AI 用量；取不到的字段占位 "-"。
+// 真实渲染断言，测试数据通过 props 注入。
+
+afterEach(() => cleanup());
+
+const projects = [{ id: 'p1' }, { id: 'p2' }, { id: 'p3' }];
+const datasets = [{ id: 'd1' }, { id: 'd2' }];
+const runs = [
+  { id: 'r1', status: 'running', result: null },
+  { id: 'r2', status: 'queued', result: null },
+  { id: 'r3', status: 'succeeded', result: { metrics: {} } },
+  { id: 'r4', status: 'succeeded', result: { metrics: {} } }
+];
+
+describe('ProjectMetricRow (real render, 4 metric cards)', () => {
+  it('renders a metric-card row: 项目/数据集/回测 running+done/AI 用量, values visible', () => {
+    const { container } = render(ProjectMetricRow, {
+      props: {
+        projects, datasets, runs,
+        usage: { totals: { input_tokens: 1200, output_tokens: 340, requests: 7 } }
+      }
+    });
+    const cards = container.querySelectorAll('[data-testid="metric-card"]');
+    expect(cards.length).toBe(4);
+    expect(screen.getByText('我的项目')).toBeTruthy();
+    expect(screen.getByText('数据集')).toBeTruthy();
+    expect(screen.getByText('回测')).toBeTruthy();
+    expect(screen.getByText('AI 用量')).toBeTruthy();
+    // 数字直接可见：项目卡/数据集卡与回测拆分值
+    const values = [...container.querySelectorAll('.metric-card .mvalue')].map((n) => n.textContent!.replace(/\s+/g, ' ').trim());
+    expect(values[0]).toBe('3');
+    expect(values[1]).toBe('2');
+    expect(values[2]).toContain('运行中');
+    expect(values[2]).toContain('2');
+    expect(values[2]).toContain('已完成');
+    expect(values[2]).toContain('2');
+    expect(screen.getByText('7 次')).toBeTruthy();
+  });
+
+  it('usage unavailable → "-" placeholder + TODO marker on the card', () => {
+    const { container } = render(ProjectMetricRow, {
+      props: { projects, datasets, runs, usage: null }
+    });
+    const cards = [...container.querySelectorAll('[data-testid="metric-card"]')];
+    const usage = cards.at(-1)!;
+    expect(usage.textContent).toContain('-');
+    expect(usage.getAttribute('data-todo') ?? '').toContain('TODO');
+  });
+
+  it('runs card splits 运行中 / 已完成', () => {
+    render(ProjectMetricRow, { props: { projects, datasets, runs, usage: null } });
+    expect(screen.getByText(/运行中/)).toBeTruthy();
+    expect(screen.getByText(/已完成/)).toBeTruthy();
+  });
+});