KPI tile

KpiTile.tsxAssembles Delta and the freshness dot. The context slot is not optional.Copy

import { Card } from "@/components/ui/card";
import { Delta } from "../delta-indicator/Delta";
import { Sparkline } from "../sparkline/Sparkline";
import { freshness, FRESHNESS_COLOR } from "../freshness-indicator/freshness";
import type { Polarity } from "../red-green-direction/direction";

/**
 * A tile is a composition, not a primitive.
 *
 * shadcn gives you the Card. What it cannot give you is the rule that a number
 * without context is a decoration: the viewer needs to know which way it moved,
 * against what, and how old it is. So `delta` and `lastArrival` are required
 * props rather than optional garnish, and a tile that cannot supply them should
 * be a plain figure instead of pretending to be a KPI.
 */
export function KpiTile({
  label,
  value,
  delta,
  window,
  polarity = "higher-is-better",
  lastArrival,
  expectedEveryMs,
  now,
  trend,
}: {
  label: string;
  value: string;
  delta: number;
  window: string;
  polarity?: Polarity;
  lastArrival: Date;
  expectedEveryMs: number;
  /** The clock to age against. Defaults to now; pass one to render on a server. */
  now?: Date;
  /** The shape that got here: the third context signal, beside the delta. */
  trend?: number[];
}) {
  const { state } = freshness(lastArrival, expectedEveryMs, now);
  return (
    <Card className="p-4">
      <div className="flex items-start justify-between gap-2">
        <p className="text-xs text-muted-foreground">{label}</p>
        <span
          className="mt-1 size-2 shrink-0 rounded-full"
          style={{ background: FRESHNESS_COLOR[state] }}
          title={`data is ${state}`}
        />
      </div>
      <p className="mt-1 text-2xl font-semibold tabular-nums text-card-foreground">{value}</p>
      {trend && (
        <div className="mt-2 text-chart-1">
          <Sparkline values={trend} width={130} height={26} />
        </div>
      )}
      <Delta value={delta} window={window} polarity={polarity} />
    </Card>
  );
}

demo.tsxHow it is called: label, value, delta, window, and when the data last arrived.Copy

import { KpiTile } from "./KpiTile";

/**
 * One tile with its context signals: the delta, the trend, the window, and
 * the freshness dot. The clock is fixed so the dot renders the same on the
 * server and in the browser.
 */
const NOW = new Date("2026-09-15T09:00:00Z");

export default function Demo() {
  return (
    <div className="w-[272px]">
      <KpiTile
        label="Checkout success"
        value="99.4%"
        delta={0.3}
        window="Last 24 hours"
        trend={[98.6, 98.9, 98.5, 99.2, 99.0, 99.4, 99.3, 99.4]}
        lastArrival={new Date(NOW.getTime() - 40_000)}
        expectedEveryMs={60_000}
        now={NOW}
      />
    </div>
  );
}