feat(stats): quantile-scaled, annotated calendar heatmap

Replace the linear count/max alpha with quantile buckets (GitHub-style)
so a single outlier day no longer flattens the rest of the graph, and
render best/median/worst day labels inside their cells.

- Add buildCalendarScale utility with empty-bucket handling.
- Make CalendarHeatmap size, gap, and annotations configurable; align
  weeks to Monday.
- Expand the community calendar to 90 days, add play totals/averages and
  all-time best day, and format large numbers with locale separators.

src/lib/components/charts/CalendarHeatmap.svelte

@@ -1,22 +1,39 @@
 <script lang="ts">
+	import { buildCalendarScale } from '$lib/utils/calendar-scale';
+
 	interface Props {
 		data: { date: string; count: number }[];
 		color?: string;
+		/** Pixel size of each day square. */
+		cellSize?: number;
+		/** Gap between squares in pixels. */
+		gap?: number;
+		/** Optional date → short label rendered inside the square. */
+		annotations?: Record<string, string>;
 	}
-	let { data, color = '52,211,153' }: Props = $props();
+	let {
+		data,
+		color = '52,211,153',
+		cellSize = 12,
+		gap = 3,
+		annotations = {}
+	}: Props = $props();
 
 	const values = $derived(new Map(data.map((d) => [d.date, d.count])));
-	const max = $derived(Math.max(1, ...data.map((d) => d.count)));
+	const scale = $derived(buildCalendarScale(data.map((d) => d.count)));
+	const fontSize = $derived(Math.max(8, Math.round(cellSize * 0.42)));
+	const radius = $derived(Math.max(2, Math.round(cellSize * 0.16)));
 
-	// Build Sunday-aligned weeks ending on the last date.
+	// Build Monday-aligned weeks ending on the last date (weekend at the bottom).
 	const weeks = $derived.by(() => {
 		if (data.length === 0) return [] as { date: string; inRange: boolean }[][];
+		const mondayOffset = (date: Date) => (date.getUTCDay() + 6) % 7;
 		const first = new Date(data[0].date + 'T00:00:00Z');
 		const start = new Date(first);
-		start.setUTCDate(start.getUTCDate() - start.getUTCDay());
+		start.setUTCDate(start.getUTCDate() - mondayOffset(start));
 		const last = new Date(data[data.length - 1].date + 'T00:00:00Z');
 		const end = new Date(last);
-		end.setUTCDate(end.getUTCDate() + (6 - end.getUTCDay()));
+		end.setUTCDate(end.getUTCDate() + (6 - mondayOffset(end)));
 		const range = new Set(data.map((d) => d.date));
 		const out: { date: string; inRange: boolean }[][] = [];
 		let cursor = new Date(start);
@@ -34,25 +51,55 @@
 </script>
 
 <div class="overflow-x-auto">
-	<div class="flex gap-1">
-		<div class="flex flex-col justify-between py-0.5 text-[9px] text-gray-500">
-			<span>Sun</span><span>Wed</span><span>Sat</span>
+	<div class="flex" style={`gap:${Math.max(4, gap)}px`}>
+		<div
+			class="flex flex-col justify-between py-0.5 text-gray-500"
+			style={`font-size:${fontSize}px`}
+		>
+			<span>Mon</span><span>Thu</span><span>Sun</span>
 		</div>
-		<div class="flex gap-[3px]">
+		<div class="flex" style={`gap:${gap}px`}>
 			{#each weeks as week, wi (wi)}
-				<div class="flex flex-col gap-[3px]">
+				<div class="flex flex-col" style={`gap:${gap}px`}>
 					{#each week as cell (cell.date)}
 						{@const count = values.get(cell.date) ?? 0}
+						{@const alpha = scale.alphaFor(count) || 0.06}
+						{@const label = annotations[cell.date]}
 						<div
-							class="h-3 w-3 rounded-[2px]"
-							style={cell.inRange
-								? `background:rgba(${color},${(0.12 + 0.88 * (count / max)).toFixed(3)})`
-								: 'background:transparent'}
-							title={cell.inRange ? `${cell.date}: ${count} finishes` : cell.date}
-						></div>
+							class="cell-label flex items-center justify-center font-semibold tabular-nums"
+							data-pale={label && alpha < 0.4 ? 'true' : undefined}
+							style={`width:${cellSize}px;height:${cellSize}px;border-radius:${radius}px;font-size:${fontSize}px;line-height:1;${
+								cell.inRange ? `background:rgba(${color},${alpha})` : 'background:transparent'
+							}`}
+							title={cell.inRange
+								? `${cell.date}: ${count.toLocaleString('en-US')} finishes`
+								: cell.date}
+						>{label ?? ''}</div>
 					{/each}
 				</div>
 			{/each}
 		</div>
 	</div>
 </div>
+
+<style>
+	/*
+	 * Annotated numbers need to read on both light and dark cell backgrounds.
+	 * Intensity is the dominant factor: the bright/high buckets are light enough
+	 * for dark ink in either theme, while the lowest bucket is a dark green on a
+	 * dark page and needs light ink there.
+	 */
+	.cell-label {
+		color: rgb(17 24 39 / 0.95);
+	}
+
+	:global(html.dark) .cell-label[data-pale='true'] {
+		color: rgb(249 250 251 / 0.95);
+	}
+
+	@media (prefers-color-scheme: dark) {
+		:global(html:not(.light)) .cell-label[data-pale='true'] {
+			color: rgb(249 250 251 / 0.95);
+		}
+	}
+</style>

src/lib/utils/calendar-scale.ts

@@ -0,0 +1,96 @@
+/**
+ * Quantile-bucketed color scale for calendar/heatmap charts.
+ *
+ * A naive `count / max` alpha collapses most cells into the same pale shade when
+ * a single day is an outlier. Bucketing by quantiles of the non-zero values
+ * (like GitHub's contribution graph) keeps typical variation visible and never
+ * changes when a new all-time-high day appears.
+ */
+
+export interface CalendarBucket {
+	/** Lowest count in this bucket. */
+	min: number;
+	/** Highest count in this bucket. */
+	max: number;
+	/** Alpha (0..1) applied to the base color. */
+	alpha: number;
+	/** How many non-zero days fall in this bucket. */
+	days: number;
+}
+
+export interface CalendarScale {
+	min: number;
+	max: number;
+	/** Non-empty intensity buckets, low → high. Zero is rendered separately. */
+	buckets: CalendarBucket[];
+	/** Alpha for a raw count (0 for a zero/empty day). */
+	alphaFor: (count: number) => number;
+}
+
+/** Linear-interpolated quantile over an already-sorted ascending array. */
+export function quantile(sorted: number[], q: number): number {
+	if (sorted.length === 0) return 0;
+	if (sorted.length === 1) return sorted[0];
+	const pos = (sorted.length - 1) * q;
+	const base = Math.floor(pos);
+	const rest = pos - base;
+	const next = sorted[base + 1];
+	return next === undefined ? sorted[base] : sorted[base] + rest * (next - sorted[base]);
+}
+
+/**
+ * Build a quantile scale from a list of daily counts.
+ *
+ * The non-zero counts are split into `steps` intensity buckets at evenly spaced
+ * quantiles; duplicate-heavy data is tolerated because empty buckets are dropped.
+ */
+export function buildCalendarScale(counts: number[], steps = 4): CalendarScale {
+	const nonzero = counts.filter((c) => c > 0).sort((a, b) => a - b);
+	const min = counts.length ? Math.min(...counts) : 0;
+	const max = counts.length ? Math.max(...counts) : 0;
+
+	if (nonzero.length === 0) {
+		return { min, max, buckets: [], alphaFor: () => 0 };
+	}
+
+	const alphas =
+		steps <= 1
+			? [0.9]
+			: Array.from({ length: steps }, (_, i) => 0.28 + (0.72 * i) / (steps - 1));
+
+	const thresholds: number[] = [];
+	for (let i = 1; i < steps; i++) thresholds.push(quantile(nonzero, i / steps));
+
+	const bucketIndex = (count: number): number => {
+		if (count <= 0) return -1;
+		let index = 0;
+		for (const threshold of thresholds) {
+			if (count > threshold) index++;
+		}
+		return index;
+	};
+
+	const buckets: CalendarBucket[] = alphas.map((alpha) => ({
+		alpha,
+		min: Number.POSITIVE_INFINITY,
+		max: Number.NEGATIVE_INFINITY,
+		days: 0
+	}));
+
+	for (const count of nonzero) {
+		const bucket = buckets[bucketIndex(count)];
+		bucket.min = Math.min(bucket.min, count);
+		bucket.max = Math.max(bucket.max, count);
+		bucket.days++;
+	}
+
+	return {
+		min,
+		max,
+		buckets: buckets.filter((bucket) => bucket.days > 0),
+		alphaFor: (count: number) => {
+			const index = bucketIndex(count);
+			return index < 0 ? 0 : alphas[index];
+		}
+	};
+}

src/lib/utils/stats-format.ts

@@ -1,7 +1,7 @@
 /** Small formatting helpers shared by the stats dashboard components. */
 
 export function numOrDash(n: number | null | undefined): string {
-	return n === null || n === undefined ? '—' : String(n);
+	return n === null || n === undefined ? '—' : n.toLocaleString('en-US');
 }
 
 export function pctOrDash(n: number | null | undefined): string {

src/routes/global/+page.svelte

@@ -5,11 +5,50 @@
 	import { formatDateLabel, numOrDash } from '$lib/utils/stats-format';
 
 	let { data }: { data: PageData } = $props();
+
+	const calendar = $derived(data.calendar);
+	const active = $derived(calendar.filter((d) => d.count > 0));
+
+	const total = $derived(calendar.reduce((sum, d) => sum + d.count, 0));
+	const avgPerDay = $derived(calendar.length ? total / calendar.length : 0);
+
+	const bestDay = $derived(
+		active.reduce<{ date: string; count: number } | null>(
+			(best, d) => (best === null || d.count > best.count ? d : best),
+			null
+		)
+	);
+	const worstDay = $derived(
+		active.reduce<{ date: string; count: number } | null>(
+			(worst, d) => (worst === null || d.count < worst.count ? d : worst),
+			null
+		)
+	);
+	const medianDay = $derived.by(() => {
+		if (active.length === 0) return null;
+		const sorted = [...active].sort((a, b) => a.count - b.count);
+		return sorted[Math.floor((sorted.length - 1) / 2)];
+	});
+
+	/** Compact enough to sit inside a day square. */
+	function compactCount(n: number): string {
+		if (n >= 10000) return `${Math.round(n / 1000)}k`;
+		if (n >= 1000) return `${(n / 1000).toFixed(1)}k`;
+		return String(n);
+	}
+
+	const annotations = $derived.by(() => {
+		const out: Record<string, string> = {};
+		for (const day of [bestDay, medianDay, worstDay]) {
+			if (day) out[day.date] = compactCount(day.count);
+		}
+		return out;
+	});
 </script>
 
 <svelte:head>
 	<title>Community Stats | Bibdle</title>
-	<meta name="description" content="Bibdle community statistics, as of yesterday." />
+	<meta name="description" content="Bibdle community statistics, as of the latest completed day." />
 </svelte:head>
 
 <div class="mx-auto max-w-3xl px-4 py-8">
@@ -20,7 +59,7 @@
 
 	<div class="grid grid-cols-2 gap-3 md:grid-cols-3">
 		<Container class="p-4 w-full items-start text-left">
-			<p class="text-[11px] font-semibold uppercase tracking-wider text-gray-600 dark:text-gray-400">All-time finishes</p>
+			<p class="text-[11px] font-semibold uppercase tracking-wider text-gray-600 dark:text-gray-400">All-time plays</p>
 			<p class="text-2xl font-bold text-gray-900 dark:text-gray-100">{numOrDash(data.completions)}</p>
 		</Container>
 		<Container class="p-4 w-full items-start text-left">
@@ -36,21 +75,61 @@
 			<p class="text-2xl font-bold text-gray-900 dark:text-gray-100">{numOrDash(data.monthlyPlayers)}</p>
 		</Container>
 		<Container class="p-4 w-full items-start text-left">
-			<p class="text-[11px] font-semibold uppercase tracking-wider text-gray-600 dark:text-gray-400">Yesterday's finishes</p>
+			<p class="text-[11px] font-semibold uppercase tracking-wider text-gray-600 dark:text-gray-400">Latest day's plays</p>
 			<p class="text-2xl font-bold text-gray-900 dark:text-gray-100">{numOrDash(data.yesterdayCompletions)}</p>
 		</Container>
 		<Container class="p-4 w-full items-start text-left">
-			<p class="text-[11px] font-semibold uppercase tracking-wider text-gray-600 dark:text-gray-400">Avg guesses yesterday</p>
+			<p class="text-[11px] font-semibold uppercase tracking-wider text-gray-600 dark:text-gray-400">Avg guesses that day</p>
 			<p class="text-2xl font-bold text-gray-900 dark:text-gray-100">{numOrDash(data.yesterdayAvgGuesses)}</p>
 		</Container>
 	</div>
 
-	<Container class="mt-3 p-4 w-full items-stretch text-left gap-2">
-		<p class="font-semibold text-gray-900 dark:text-gray-100">Daily finishes (last 30 days)</p>
-		<CalendarHeatmap data={data.calendar} />
+	<Container class="mt-3 p-4 w-full items-stretch text-left gap-3">
+		<p class="font-semibold text-gray-900 dark:text-gray-100">Daily plays (last {calendar.length} days)</p>
+		<div class="flex flex-col gap-4 sm:flex-row sm:items-start">
+			<div class="flex flex-col gap-1">
+				<CalendarHeatmap data={calendar} cellSize={22} annotations={annotations} />
+				<p class="text-[10px] text-gray-500 dark:text-gray-400">
+					Numbers mark the best, median, and least popular days.
+				</p>
+			</div>
+
+			<div class="flex min-w-0 flex-1 flex-col gap-4">
+				<dl class="grid grid-cols-2 gap-x-4 gap-y-3 text-sm">
+					<div>
+						<dt class="text-[11px] uppercase tracking-wider text-gray-500 dark:text-gray-400">{calendar.length}-day plays</dt>
+						<dd class="font-semibold tabular-nums text-gray-900 dark:text-gray-100">{numOrDash(total)}</dd>
+					</div>
+					<div>
+						<dt class="text-[11px] uppercase tracking-wider text-gray-500 dark:text-gray-400">Daily average</dt>
+						<dd class="font-semibold tabular-nums text-gray-900 dark:text-gray-100">
+							{avgPerDay.toLocaleString('en-US', { maximumFractionDigits: 1 })}
+						</dd>
+					</div>
+					{#if bestDay}
+						<div>
+							<dt class="text-[11px] uppercase tracking-wider text-gray-500 dark:text-gray-400">Best day ({calendar.length}d)</dt>
+							<dd class="font-semibold tabular-nums text-gray-900 dark:text-gray-100">
+								{numOrDash(bestDay.count)}
+								<span class="font-normal text-gray-500 dark:text-gray-400">on {formatDateLabel(bestDay.date)}</span>
+							</dd>
+						</div>
+					{/if}
+					{#if data.bestDayAllTime}
+						<div>
+							<dt class="text-[11px] uppercase tracking-wider text-gray-500 dark:text-gray-400">Best day · all-time</dt>
+							<dd class="font-semibold tabular-nums text-gray-900 dark:text-gray-100">
+								{numOrDash(data.bestDayAllTime.count)}
+								<span class="font-normal text-gray-500 dark:text-gray-400">on {formatDateLabel(data.bestDayAllTime.date)}</span>
+							</dd>
+						</div>
+					{/if}
+				</dl>
+			</div>
+		</div>
 	</Container>
 
 	<p class="mt-4 text-center text-xs text-gray-500 dark:text-gray-500">
-		Updated once a day from completed games. <a class="underline hover:text-gray-300" href="/">Play today's verse →</a>
+		Updated once a day from completed games.<br /> <a class="underline hover:text-gray-300" href="/">Play today's verse →</a>
 	</p>
 </div>