feat: add KpiStrip composite for horizontal metric card rows

Horizontal grid of KPI cards with labels, values, trend indicators,
subtitles, and optional sparklines. Uses CSS custom property for
per-card accent border color. 12 tests included.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/design-system/composites/KpiStrip/KpiStrip.module.css

@@ -0,0 +1,79 @@
+.kpiStrip {
+  display: grid;
+  gap: 12px;
+  margin-bottom: 20px;
+}
+
+.kpiCard {
+  background: var(--bg-surface);
+  border: 1px solid var(--border-subtle);
+  border-radius: var(--radius-lg);
+  padding: 16px 18px 12px;
+  box-shadow: var(--shadow-card);
+  position: relative;
+  overflow: hidden;
+  transition: box-shadow 0.15s;
+}
+
+.kpiCard:hover {
+  box-shadow: var(--shadow-md);
+}
+
+.kpiCard::before {
+  content: '';
+  position: absolute;
+  top: 0;
+  left: 0;
+  right: 0;
+  height: 3px;
+  background: linear-gradient(90deg, var(--kpi-border-color), transparent);
+}
+
+.label {
+  font-size: 10px;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.6px;
+  color: var(--text-muted);
+  margin-bottom: 6px;
+}
+
+.valueRow {
+  display: flex;
+  align-items: baseline;
+  gap: 6px;
+  margin-bottom: 4px;
+}
+
+.value {
+  font-family: var(--font-mono);
+  font-size: 26px;
+  font-weight: 600;
+  line-height: 1.2;
+  color: var(--text-primary);
+}
+
+.trend {
+  font-family: var(--font-mono);
+  font-size: 11px;
+  display: inline-flex;
+  align-items: center;
+  gap: 2px;
+  margin-left: auto;
+}
+
+.trendSuccess { color: var(--success); }
+.trendWarning { color: var(--warning); }
+.trendError   { color: var(--error); }
+.trendMuted   { color: var(--text-muted); }
+
+.subtitle {
+  font-size: 11px;
+  color: var(--text-muted);
+  margin-top: 2px;
+}
+
+.sparkline {
+  margin-top: 8px;
+  height: 32px;
+}

src/design-system/composites/KpiStrip/KpiStrip.test.tsx

@@ -0,0 +1,86 @@
+import { describe, it, expect } from 'vitest'
+import { render, screen } from '@testing-library/react'
+import { KpiStrip } from './KpiStrip'
+import type { KpiItem } from './KpiStrip'
+
+const sampleItems: KpiItem[] = [
+  { label: 'Total', value: 42 },
+  { label: 'Active', value: '18', trend: { label: '+3', variant: 'success' } },
+  { label: 'Errors', value: 5, subtitle: 'last 24h', sparkline: [1, 3, 2, 5, 4] },
+]
+
+describe('KpiStrip', () => {
+  it('renders all items', () => {
+    const { container } = render(<KpiStrip items={sampleItems} />)
+    const cards = container.querySelectorAll('[class*="kpiCard"]')
+    expect(cards).toHaveLength(3)
+  })
+
+  it('renders labels and values', () => {
+    render(<KpiStrip items={sampleItems} />)
+    expect(screen.getByText('Total')).toBeInTheDocument()
+    expect(screen.getByText('42')).toBeInTheDocument()
+    expect(screen.getByText('Active')).toBeInTheDocument()
+    expect(screen.getByText('18')).toBeInTheDocument()
+  })
+
+  it('renders trend with correct text', () => {
+    render(<KpiStrip items={sampleItems} />)
+    expect(screen.getByText('+3')).toBeInTheDocument()
+  })
+
+  it('applies variant class to trend (trendSuccess)', () => {
+    render(<KpiStrip items={sampleItems} />)
+    const trend = screen.getByText('+3')
+    expect(trend.className).toContain('trendSuccess')
+  })
+
+  it('hides trend when omitted', () => {
+    render(<KpiStrip items={[{ label: 'No Trend', value: 10 }]} />)
+    const { container } = render(<KpiStrip items={[{ label: 'No Trend2', value: 10 }]} />)
+    const trends = container.querySelectorAll('[class*="trend"]')
+    expect(trends).toHaveLength(0)
+  })
+
+  it('renders subtitle', () => {
+    render(<KpiStrip items={sampleItems} />)
+    expect(screen.getByText('last 24h')).toBeInTheDocument()
+  })
+
+  it('renders sparkline when data provided', () => {
+    const { container } = render(<KpiStrip items={sampleItems} />)
+    const svgs = container.querySelectorAll('svg')
+    expect(svgs.length).toBeGreaterThanOrEqual(1)
+  })
+
+  it('accepts className prop', () => {
+    const { container } = render(<KpiStrip items={sampleItems} className="custom" />)
+    expect(container.firstChild).toHaveClass('custom')
+  })
+
+  it('handles empty items array', () => {
+    const { container } = render(<KpiStrip items={[]} />)
+    const cards = container.querySelectorAll('[class*="kpiCard"]')
+    expect(cards).toHaveLength(0)
+  })
+
+  it('uses default border color (--amber) when borderColor omitted', () => {
+    const { container } = render(<KpiStrip items={[{ label: 'Default', value: 1 }]} />)
+    const card = container.querySelector('[class*="kpiCard"]') as HTMLElement
+    expect(card.style.getPropertyValue('--kpi-border-color')).toBe('var(--amber)')
+  })
+
+  it('applies custom borderColor', () => {
+    const items: KpiItem[] = [{ label: 'Custom', value: 1, borderColor: 'var(--teal)' }]
+    const { container } = render(<KpiStrip items={items} />)
+    const card = container.querySelector('[class*="kpiCard"]') as HTMLElement
+    expect(card.style.getPropertyValue('--kpi-border-color')).toBe('var(--teal)')
+  })
+
+  it('renders trend with muted variant by default', () => {
+    const items: KpiItem[] = [{ label: 'Muted', value: 1, trend: { label: '0%' } }]
+    render(<KpiStrip items={items} />)
+    const trend = screen.getByText('0%')
+    expect(trend.className).toContain('trendMuted')
+  })
+})

src/design-system/composites/KpiStrip/KpiStrip.tsx

@@ -0,0 +1,71 @@
+import styles from './KpiStrip.module.css'
+import { Sparkline } from '../../primitives/Sparkline/Sparkline'
+import type { CSSProperties } from 'react'
+
+export interface KpiItem {
+  label: string
+  value: string | number
+  trend?: { label: string; variant?: 'success' | 'warning' | 'error' | 'muted' }
+  subtitle?: string
+  sparkline?: number[]
+  borderColor?: string
+}
+
+export interface KpiStripProps {
+  items: KpiItem[]
+  className?: string
+}
+
+const trendClassMap: Record<string, string> = {
+  success: styles.trendSuccess,
+  warning: styles.trendWarning,
+  error: styles.trendError,
+  muted: styles.trendMuted,
+}
+
+export function KpiStrip({ items, className }: KpiStripProps) {
+  const stripClasses = [styles.kpiStrip, className ?? ''].filter(Boolean).join(' ')
+  const gridStyle: CSSProperties = {
+    gridTemplateColumns: items.length > 0 ? `repeat(${items.length}, 1fr)` : undefined,
+  }
+
+  return (
+    <div className={stripClasses} style={gridStyle}>
+      {items.map((item) => {
+        const borderColor = item.borderColor ?? 'var(--amber)'
+        const cardStyle: CSSProperties & Record<string, string> = {
+          '--kpi-border-color': borderColor,
+        }
+        const trendVariant = item.trend?.variant ?? 'muted'
+        const trendClass = trendClassMap[trendVariant] ?? styles.trendMuted
+
+        return (
+          <div key={item.label} className={styles.kpiCard} style={cardStyle}>
+            <div className={styles.label}>{item.label}</div>
+            <div className={styles.valueRow}>
+              <span className={styles.value}>{item.value}</span>
+              {item.trend && (
+                <span className={`${styles.trend} ${trendClass}`}>
+                  {item.trend.label}
+                </span>
+              )}
+            </div>
+            {item.subtitle && (
+              <div className={styles.subtitle}>{item.subtitle}</div>
+            )}
+            {item.sparkline && item.sparkline.length >= 2 && (
+              <div className={styles.sparkline}>
+                <Sparkline
+                  data={item.sparkline}
+                  color={borderColor}
+                  width={200}
+                  height={32}
+                />
+              </div>
+            )}
+          </div>
+        )
+      })}
+    </div>
+  )
+}

src/design-system/composites/index.ts

@@ -14,6 +14,8 @@ export { DetailPanel } from './DetailPanel/DetailPanel'
 export { Dropdown } from './Dropdown/Dropdown'
 export { EventFeed } from './EventFeed/EventFeed'
 export { GroupCard } from './GroupCard/GroupCard'
+export { KpiStrip } from './KpiStrip/KpiStrip'
+export type { KpiItem, KpiStripProps } from './KpiStrip/KpiStrip'
 export type { FeedEvent } from './EventFeed/EventFeed'
 export { FilterBar } from './FilterBar/FilterBar'
 export { LineChart } from './LineChart/LineChart'