fix(chart): label the sample latency curve as sample data

src/App.tsx

@@ -89,7 +89,7 @@ export default function App() {
 
           <div className="grid grid-cols-1 gap-3.5 lg:grid-cols-[1.9fr_1fr]">
             <StalePanel reason={staleTraceDerived}>
-              <LatencyChart series={data.latencyP95} />
+              <LatencyChart series={data.latencyP95} sample={conn.status === 'sample'} />
             </StalePanel>
             <StalePanel reason={staleTraceDerived}>
               <StatusMix traces={data.traces} />

src/components/latency-chart.test.tsx

@@ -141,6 +141,36 @@ describe('latency chart with no samples', () => {
   })
 })
 
+describe('latency chart on sample data', () => {
+  afterEach(cleanup)
+
+  /**
+   * With no platform the console draws a generated curve. The top bar says SAMPLE
+   * DATA, but this header said "rolling window" — a claim about where the numbers
+   * came from that a generated curve cannot make. The header has to say it instead.
+   */
+  it('says the curve is sample data, not a window', () => {
+    const { getByText, queryByText, getByRole } = render(<LatencyChart series={[34, 41, 38]} sample />)
+    expect(getByText(/sample data/)).toBeTruthy()
+    expect(queryByText(/rolling window/), 'a generated curve claimed to be a window').toBeNull()
+    expect(getByRole('img').getAttribute('aria-label')).toMatch(/sample data/)
+  })
+
+  it('still draws the curve, so the demo stays explorable', () => {
+    // Every other card shows sample values too; an empty chart beside them would
+    // single this one out without making the screen any more honest.
+    const { container } = render(<LatencyChart series={[34, 41, 38]} sample />)
+    expect(container.querySelector('polyline')).not.toBeNull()
+  })
+
+  it('drops the label once real samples replace it', () => {
+    const { getByText, queryByText, rerender } = render(<LatencyChart series={[34, 41, 38]} sample />)
+    rerender(<LatencyChart series={[12, 40]} />)
+    expect(getByText(/rolling window/)).toBeTruthy()
+    expect(queryByText(/sample data/)).toBeNull()
+  })
+})
+
 describe('status mix', () => {
   afterEach(cleanup)
 

src/components/latency-chart.tsx

@@ -33,8 +33,15 @@ function niceTicks(max: number, count = 4): number[] {
  */
 const EMPTY_SCALE_MAX = 100
 
-/** Single-series p95 latency area with a crosshair+tooltip. One hue (telemetry), no legend needed. */
-export function LatencyChart({ series }: { series: number[] }) {
+/**
+ * Single-series p95 latency area with a crosshair+tooltip. One hue (telemetry), no legend needed.
+ *
+ * `sample` marks a series this console generated because no platform answered. The
+ * top bar already says SAMPLE DATA, but the chart is the one card whose header made
+ * a claim of its own — "rolling window" — and a generated curve is not a window onto
+ * anything. The header names what it is instead.
+ */
+export function LatencyChart({ series, sample = false }: { series: number[]; sample?: boolean }) {
   const gradId = useId()
   const svgRef = useRef<SVGSVGElement>(null)
   const [hover, setHover] = useState<number | null>(null)
@@ -67,7 +74,7 @@ export function LatencyChart({ series }: { series: number[] }) {
       <CardHeader className="flex items-baseline justify-between pb-2">
         <CardTitle className="text-[13.5px] font-semibold">Latency p95 over time</CardTitle>
         <span className="font-mono text-[11px] text-muted-foreground">
-          {empty ? 'ms · default scale' : 'ms · rolling window'}
+          {sample ? 'ms · sample data' : empty ? 'ms · default scale' : 'ms · rolling window'}
         </span>
       </CardHeader>
       <div className="relative px-2.5">
@@ -77,7 +84,7 @@ export function LatencyChart({ series }: { series: number[] }) {
           className="block h-[190px] w-full touch-none"
           preserveAspectRatio="none"
           role="img"
-          aria-label="p95 latency over the rolling window"
+          aria-label={sample ? 'p95 latency, generated sample data' : 'p95 latency over the rolling window'}
           onPointerMove={onMove}
           onPointerLeave={() => setHover(null)}
         >