admin: fix dashboard phantom scroll, drop last-failure column from upstream table

the chart's screen-reader table wore srOnly directly; overflow and
height do not apply to a table box, so it laid out 1200px tall below
the page while clip-path hid the paint. wrap it in a hidden div, which
clips properly and keeps the table role. failure detail is the
diagnostics page's job since milestone 27; the column and the now
dead formatAge go.

admin/src/features/dashboard/DashboardPage.test.tsx

@@ -193,7 +193,6 @@ test("dashboard renders stats, chart, disk card, upstream table and health banne
 	expect(screen.getByText("https://dns.example/dns-query")).toBeTruthy();
 	expect(screen.getByText("90.0%")).toBeTruthy();
 	expect(screen.getByText("100.0%")).toBeTruthy();
-	expect(screen.getByText("timeout · 3h ago")).toBeTruthy();
 	expect(screen.getByText("1/2 available")).toBeTruthy();
 });
 

admin/src/features/dashboard/TimeseriesChart.test.tsx

@@ -0,0 +1,51 @@
+import { render, screen, within } from "@testing-library/react";
+import * as stylex from "@stylexjs/stylex";
+import type { StatsTimeseries } from "@/lib/types";
+import { styles as shared } from "@/ui/styles";
+import TimeseriesChart from "./TimeseriesChart";
+
+const SINCE = 1_700_000_000;
+
+function timeseries(bucketCount: number): StatsTimeseries {
+	return {
+		period: "24h",
+		since: SINCE,
+		until: SINCE + bucketCount * 1800,
+		bucket_seconds: 1800,
+		buckets: Array.from({ length: bucketCount }, (_, i) => ({
+			ts: SINCE + i * 1800,
+			queries: i + 1,
+			blocked: 1,
+			cached: 1,
+		})),
+	};
+}
+
+/** The element wearing the shared hidden style, found by its compiled classes. */
+function hiddenElement(container: HTMLElement): Element | null {
+	const classes = stylex.props(shared.srOnly).className?.split(" ").filter(Boolean) ?? [];
+	expect(classes.length).toBeGreaterThan(0);
+	return container.querySelector(classes.map((name) => `.${name}`).join(""));
+}
+
+test("the data table is the SVG's accessible equivalent", () => {
+	render(<TimeseriesChart data={timeseries(3)} />);
+
+	expect(screen.getByRole("img", { name: /queries over time/i })).toBeTruthy();
+	const table = screen.getByRole("table", { name: "Queries per time bucket" });
+	expect(within(table).getAllByRole("row").length).toBe(4);
+});
+
+/**
+ * `overflow` does not apply to a table box and `height` on one is a minimum, so
+ * the hidden style has to sit on a block container wrapping the table. Worn by
+ * the table itself it clips the paint but not the layout, and 48 invisible rows
+ * push the document's scroll height a screen past the app shell.
+ */
+test("the hidden data table is clipped by a block wrapper, not by the table itself", () => {
+	const { container } = render(<TimeseriesChart data={timeseries(48)} />);
+
+	const hidden = hiddenElement(container);
+	expect(hidden?.tagName).toBe("DIV");
+	expect(hidden?.querySelector("table")).not.toBeNull();
+});

admin/src/features/dashboard/TimeseriesChart.tsx

@@ -292,29 +292,31 @@ export default function TimeseriesChart({ data }: { data: StatsTimeseries }) {
 					</li>
 				))}
 			</ul>
-			<table {...stylex.props(shared.srOnly)}>
-				<caption>Queries per time bucket</caption>
-				<thead>
-					<tr>
-						<th scope="col">Time</th>
-						<th scope="col">Queries</th>
-						<th scope="col">Blocked</th>
-						<th scope="col">Cached</th>
-						<th scope="col">Other</th>
-					</tr>
-				</thead>
-				<tbody>
-					{layout.bars.map((bar) => (
-						<tr key={bar.bucket.ts}>
-							<th scope="row">{formatTime(bar.bucket.ts)}</th>
-							<td>{bar.bucket.queries}</td>
-							<td>{bar.bucket.blocked}</td>
-							<td>{bar.bucket.cached}</td>
-							<td>{bar.other}</td>
+			<div {...stylex.props(shared.srOnly)}>
+				<table>
+					<caption>Queries per time bucket</caption>
+					<thead>
+						<tr>
+							<th scope="col">Time</th>
+							<th scope="col">Queries</th>
+							<th scope="col">Blocked</th>
+							<th scope="col">Cached</th>
+							<th scope="col">Other</th>
 						</tr>
-					))}
-				</tbody>
-			</table>
+					</thead>
+					<tbody>
+						{layout.bars.map((bar) => (
+							<tr key={bar.bucket.ts}>
+								<th scope="row">{formatTime(bar.bucket.ts)}</th>
+								<td>{bar.bucket.queries}</td>
+								<td>{bar.bucket.blocked}</td>
+								<td>{bar.bucket.cached}</td>
+								<td>{bar.other}</td>
+							</tr>
+						))}
+					</tbody>
+				</table>
+			</div>
 		</div>
 	);
 }

admin/src/features/dashboard/UpstreamHealthTable.test.tsx

@@ -4,14 +4,6 @@ import UpstreamHealthTable from "./UpstreamHealthTable";
 
 const NOW_S = 1_700_000_000;
 
-beforeEach(() => {
-	vi.spyOn(Date, "now").mockReturnValue(NOW_S * 1000);
-});
-
-afterEach(() => {
-	vi.restoreAllMocks();
-});
-
 const ZERO: UpstreamPeriodStats = {
 	attempts: 0,
 	successes: 0,
@@ -27,7 +19,6 @@ function period(overrides: Partial<UpstreamPeriodStats> = {}): UpstreamPeriodSta
 		successes: 90,
 		failures: 10,
 		success_rate: 0.9,
-		// 3h30m ago, far from a unit boundary.
 		last_failure_at: NOW_S - 12_600,
 		last_failure_error: "Timeout",
 		...overrides,
@@ -69,7 +60,7 @@ test("the ranged columns sit under a header naming the selected period", () => {
 	renderTable([entry()]);
 
 	expect(screen.getByRole("columnheader", { name: "Selected period · 24h" })).toBeTruthy();
-	for (const name of ["Upstream", "Status now", "Attempts", "Failures", "Success rate", "Last failure"]) {
+	for (const name of ["Upstream", "Status now", "Attempts", "Failures", "Success rate"]) {
 		expect(screen.getByRole("columnheader", { name })).toBeTruthy();
 	}
 
@@ -78,6 +69,14 @@ test("the ranged columns sit under a header naming the selected period", () => {
 	expect(screen.queryByRole("columnheader", { name: "Available" })).toBeNull();
 });
 
+test("failure detail is the Diagnostics page's job; the card never shows it", () => {
+	renderTable([entry()]);
+
+	expect(screen.queryByRole("columnheader", { name: "Last failure" })).toBeNull();
+	expect(screen.queryByText(/Timeout/)).toBeNull();
+	expect(screen.queryByText(/ago$/)).toBeNull();
+});
+
 test("status now is one word from live state, not from the window", () => {
 	renderTable([
 		entry({ url: "https://a.example/dns-query" }),
@@ -90,20 +89,7 @@ test("status now is one word from live state, not from the window", () => {
 	expect(within(rowOf("https://c.example/dns-query")).getByText("Disabled")).toBeTruthy();
 });
 
-test("last failure pairs the error name with its age, em-dash when the window holds none", () => {
-	renderTable([
-		entry({ url: "https://a.example/dns-query" }),
-		entry({
-			url: "https://b.example/dns-query",
-			period: period({ last_failure_at: null, last_failure_error: null }),
-		}),
-	]);
-
-	expect(within(rowOf("https://a.example/dns-query")).getByText("Timeout · 3h ago")).toBeTruthy();
-	expect(within(rowOf("https://b.example/dns-query")).getByText("—")).toBeTruthy();
-});
-
-test("a window with no attempts renders em-dashes and never a perfect rate", () => {
+test("a window with no attempts renders an em-dash and never a perfect rate", () => {
 	renderTable([entry({ period: ZERO })]);
 
 	const cells = within(rowOf("https://dns.example/dns-query")).getAllByRole("cell");
@@ -113,7 +99,6 @@ test("a window with no attempts renders em-dashes and never a perfect rate", ()
 		"0",
 		"0",
 		"—",
-		"—",
 	]);
 	expect(screen.queryByText("100.0%")).toBeNull();
 	expect(screen.queryByText("0.0%")).toBeNull();

admin/src/features/dashboard/UpstreamHealthTable.tsx

@@ -1,5 +1,4 @@
 import * as stylex from "@stylexjs/stylex";
-import { formatAge } from "@/lib/format";
 import type { UpstreamHealth, UpstreamHealthEntry, UpstreamPeriodStats } from "@/lib/types";
 import { styles as shared } from "@/ui/styles";
 import { colors } from "@/ui/tokens.stylex";
@@ -137,19 +136,11 @@ function successRate(period: UpstreamPeriodStats): string {
 }
 
 /**
- * The age is formatted once, when the row renders; nothing here ticks. It is
- * measured against the browser's clock rather than the response's `until`, so a
- * cached response ages visibly instead of freezing at the moment it was served.
+ * The dashboard answers availability only. Failure detail — what failed, when,
+ * and how often — is the Diagnostics page's job, so `last_failure_at` and
+ * `last_failure_error` are read there rather than repeated in this row.
  */
-function lastFailure(period: UpstreamPeriodStats, nowSeconds: number): string {
-	if (period.last_failure_at === null) return "—";
-	const age = formatAge(Math.max(0, nowSeconds - period.last_failure_at));
-	const error = period.last_failure_error;
-	return error === null || error === "" ? age : `${error} · ${age}`;
-}
-
 export default function UpstreamHealthTable({ health }: { health: UpstreamHealth }) {
-	const nowSeconds = Math.floor(Date.now() / 1000);
 	const idle = health.upstreams.length > 0 && health.upstreams.every(({ period }) => period.attempts === 0);
 
 	return (
@@ -168,7 +159,7 @@ export default function UpstreamHealthTable({ health }: { health: UpstreamHealth
 						<thead>
 							<tr {...stylex.props(styles.groupRow)}>
 								<td colSpan={2} />
-								<th scope="colgroup" colSpan={4} {...stylex.props(styles.groupHead)}>
+								<th scope="colgroup" colSpan={3} {...stylex.props(styles.groupHead)}>
 									Selected period · {health.period}
 								</th>
 							</tr>
@@ -188,9 +179,6 @@ export default function UpstreamHealthTable({ health }: { health: UpstreamHealth
 								<th scope="col" {...stylex.props(styles.th, styles.thRight)}>
 									Success rate
 								</th>
-								<th scope="col" {...stylex.props(styles.th)}>
-									Last failure
-								</th>
 							</tr>
 						</thead>
 						<tbody>
@@ -220,9 +208,6 @@ export default function UpstreamHealthTable({ health }: { health: UpstreamHealth
 										<td {...stylex.props(styles.cell, styles.cellRight, shared.tabularNums)}>
 											{successRate(upstream.period)}
 										</td>
-										<td {...stylex.props(styles.cell, styles.small, styles.muted)}>
-											{lastFailure(upstream.period, nowSeconds)}
-										</td>
 									</tr>
 								);
 							})}

admin/src/lib/format.test.ts

@@ -1,4 +1,4 @@
-import { formatAge, formatBytes, formatDuration, formatMicros, formatTime } from "@/lib/format";
+import { formatBytes, formatDuration, formatMicros, formatTime } from "@/lib/format";
 
 test("formatTime renders unix seconds in the given locale and zone", () => {
 	// 2024-01-01T00:00:00Z; ICU emits U+202F before AM/PM in recent Node.
@@ -15,23 +15,19 @@ test("formatBytes humanizes with binary units", () => {
 	expect(formatBytes(2 * 1024 ** 4)).toBe("2.0 TiB");
 });
 
-test("formatAge steps up a unit at each boundary and truncates", () => {
-	expect(formatAge(0)).toBe("0s ago");
-	expect(formatAge(59)).toBe("59s ago");
-	expect(formatAge(60)).toBe("1m ago");
-	expect(formatAge(3599)).toBe("59m ago");
-	expect(formatAge(3600)).toBe("1h ago");
-	expect(formatAge(10800)).toBe("3h ago");
-	expect(formatAge(86399)).toBe("23h ago");
-	expect(formatAge(86400)).toBe("1d ago");
-	expect(formatAge(400000)).toBe("4d ago");
-});
-
-test("formatDuration is the same span without the 'ago', and never negative", () => {
+test("formatDuration steps up a unit at each boundary and truncates", () => {
 	expect(formatDuration(0)).toBe("0s");
 	expect(formatDuration(59)).toBe("59s");
+	expect(formatDuration(60)).toBe("1m");
+	expect(formatDuration(3599)).toBe("59m");
 	expect(formatDuration(3600)).toBe("1h");
+	expect(formatDuration(10800)).toBe("3h");
+	expect(formatDuration(86399)).toBe("23h");
 	expect(formatDuration(86400)).toBe("1d");
+	expect(formatDuration(400000)).toBe("4d");
+});
+
+test("formatDuration is never negative", () => {
 	// Clock skew between the server's timestamps and the browser's clock.
 	expect(formatDuration(-5)).toBe("0s");
 });

admin/src/lib/format.ts

@@ -28,21 +28,9 @@ const AGE_UNITS = [
 ] as const;
 
 /**
- * Seconds of elapsed time → a coarse "3h ago". Truncating and single-unit on
- * purpose: this labels a snapshot the caller renders once, so a reader must not
- * take it for a live count. Nothing re-renders it as it ages.
- */
-export function formatAge(seconds: number): string {
-	for (const unit of AGE_UNITS) {
-		if (seconds >= unit.seconds) return `${Math.floor(seconds / unit.seconds)}${unit.suffix} ago`;
-	}
-	return `${Math.floor(seconds)}s ago`;
-}
-
-/**
- * Seconds of elapsed time → a coarse "3h", the same single truncated unit as
- * `formatAge` without the "ago". For a span the caller labels itself, as in
- * "active for 3h". A negative span reads "0s": clock skew is not a duration.
+ * Seconds of elapsed time → a coarse "3h". Truncating and single-unit on
+ * purpose, for a span the caller labels itself, as in "active for 3h". A
+ * negative span reads "0s": clock skew is not a duration.
  */
 export function formatDuration(seconds: number): string {
 	for (const unit of AGE_UNITS) {

admin/src/ui/styles.ts

@@ -193,7 +193,15 @@ export const styles = stylex.create({
 	mono: {
 		fontFamily: "ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace",
 	},
-	/** Visible to a screen reader only; the element keeps its place in the a11y tree. */
+	/**
+	 * Visible to a screen reader only; the element keeps its place in the a11y tree.
+	 *
+	 * Apply it to a block container. `overflow` has no effect on a table box, and
+	 * `height` on one is a minimum, so a `<table>` wearing this still lays out at
+	 * its full content height and pushes the page's scrollable overflow past the
+	 * app shell — invisible, because `clip-path` still hides the paint. Wrap the
+	 * table in a hidden `<div>` instead of hiding the table itself.
+	 */
 	srOnly: {
 		position: "absolute",
 		width: 1,