test(dashboard): find the distribution tooltip heading by test id

docs/api/openapi.yml

@@ -4526,6 +4526,99 @@ components:
       required:
       - name
       type: object
+    DashboardtypesDistributionAxes:
+      properties:
+        x:
+          allOf:
+          - $ref: '#/components/schemas/DashboardtypesDistributionXAxis'
+          description: The bucket axis.
+        "y":
+          allOf:
+          - $ref: '#/components/schemas/DashboardtypesDistributionYAxis'
+          description: The count axis.
+      type: object
+    DashboardtypesDistributionChartAppearance:
+      properties:
+        percentiles:
+          allOf:
+          - $ref: '#/components/schemas/DashboardtypesDistributionPercentiles'
+          description: Percentile markers drawn across the bucket axis.
+        stack:
+          allOf:
+          - $ref: '#/components/schemas/DashboardtypesStackMode'
+          description: 'How groups combine in a bucket: normal (default) stacks them,
+            none draws them side by side, percent stacks them as shares of the bucket.'
+      required:
+      - stack
+      type: object
+    DashboardtypesDistributionPanelSpec:
+      properties:
+        axes:
+          allOf:
+          - $ref: '#/components/schemas/DashboardtypesDistributionAxes'
+          description: The X (bucket) axis range and Y (count) axis scale.
+        chartAppearance:
+          allOf:
+          - $ref: '#/components/schemas/DashboardtypesDistributionChartAppearance'
+          description: Stacking and percentile markers.
+        formatting:
+          allOf:
+          - $ref: '#/components/schemas/DashboardtypesPanelFormatting'
+          description: Unit and decimal precision of the bucket bounds; counts take
+            no unit.
+        legend:
+          allOf:
+          - $ref: '#/components/schemas/DashboardtypesLegend'
+          description: Legend placement and series colors.
+        visualization:
+          allOf:
+          - $ref: '#/components/schemas/DashboardtypesBasicVisualization'
+          description: The time range the bucket counts are summed over.
+      type: object
+    DashboardtypesDistributionPercentiles:
+      properties:
+        enabled:
+          description: Whether percentile markers are drawn. Defaults to true.
+          type: boolean
+        values:
+          description: The percentiles to mark, each in (0, 100), at most 5, no duplicates.
+            Defaults to [50, 90, 99].
+          items:
+            format: double
+            type: number
+          nullable: true
+          type: array
+      required:
+      - enabled
+      - values
+      type: object
+    DashboardtypesDistributionXAxis:
+      properties:
+        max:
+          description: Buckets wholly above this value are hidden. Null shows them
+            all.
+          nullable: true
+          type: number
+        min:
+          description: Buckets wholly below this value are hidden. Null shows them
+            all.
+          nullable: true
+          type: number
+      type: object
+    DashboardtypesDistributionYAxis:
+      properties:
+        scale:
+          allOf:
+          - $ref: '#/components/schemas/DashboardtypesDistributionYScale'
+          description: 'How counts are spaced: linear (default) or log.'
+      required:
+      - scale
+      type: object
+    DashboardtypesDistributionYScale:
+      enum:
+      - linear
+      - log
+      type: string
     DashboardtypesDynamicVariableSignal:
       enum:
       - traces
@@ -5296,6 +5389,7 @@ components:
         mapping:
           signoz/AreaChartPanel: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesAreaChartPanelSpec'
           signoz/BarChartPanel: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesBarChartPanelSpec'
+          signoz/DistributionPanel: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesDistributionPanelSpec'
           signoz/HeatmapPanel: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesHeatmapPanelSpec'
           signoz/HistogramPanel: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesHistogramPanelSpec'
           signoz/ListPanel: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesListPanelSpec'
@@ -5318,6 +5412,7 @@ components:
       - $ref: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTextPanelSpec'
       - $ref: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesHeatmapPanelSpec'
       - $ref: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesScatterPlotPanelSpec'
+      - $ref: '#/components/schemas/DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesDistributionPanelSpec'
       type: object
     DashboardtypesPanelPluginKind:
       enum:
@@ -5332,6 +5427,7 @@ components:
       - signoz/TextPanel
       - signoz/HeatmapPanel
       - signoz/ScatterPlotPanel
+      - signoz/DistributionPanel
       type: string
     DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesAreaChartPanelSpec:
       properties:
@@ -5363,6 +5459,21 @@ components:
       - kind
       - spec
       type: object
+    DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesDistributionPanelSpec:
+      properties:
+        kind:
+          description: The panel kind.
+          enum:
+          - signoz/DistributionPanel
+          type: string
+        spec:
+          allOf:
+          - $ref: '#/components/schemas/DashboardtypesDistributionPanelSpec'
+          description: The options for this panel kind. {} accepts every default.
+      required:
+      - kind
+      - spec
+      type: object
     DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesHeatmapPanelSpec:
       properties:
         kind:
@@ -5516,9 +5627,9 @@ components:
           - $ref: '#/components/schemas/DashboardtypesPanelPlugin'
           description: 'The visualization: kind is one of signoz/TimeSeriesPanel,
             signoz/BarChartPanel, signoz/AreaChartPanel, signoz/NumberPanel, signoz/PieChartPanel,
-            signoz/TablePanel, signoz/HistogramPanel, signoz/ListPanel, signoz/TextPanel
-            or signoz/HeatmapPanel, and spec holds that kind''s options ({} accepts
-            every default).'
+            signoz/TablePanel, signoz/HistogramPanel, signoz/ListPanel, signoz/TextPanel,
+            signoz/HeatmapPanel or signoz/DistributionPanel, and spec holds that kind''s
+            options ({} accepts every default).'
         queries:
           description: The queries the panel runs. Use exactly one entry for a data
             panel and [] for signoz/TextPanel. To run several named queries or formulas,
@@ -5654,8 +5765,8 @@ components:
           - $ref: '#/components/schemas/Querybuildertypesv5RequestType'
           description: 'The result shape the panel requests: time_series for time
             series, bar, area and histogram panels, scalar for number, table and pie
-            panels, raw for list panels, heatmap for heatmap panels, trace for trace
-            panels.'
+            panels, raw for list panels, heatmap for heatmap panels, distribution
+            for distribution panels, trace for trace panels.'
         spec:
           allOf:
           - $ref: '#/components/schemas/DashboardtypesQuerySpec'
@@ -5812,9 +5923,9 @@ components:
             (builder query over AI observability traces), signoz/CompositeQuery (several
             named queries and formulas), signoz/Formula, signoz/PromQLQuery, signoz/ClickHouseSQL
             or signoz/TraceOperator, and spec holds that kind''s query. Pie and table
-            panels reject signoz/PromQLQuery; heatmap panels reject signoz/AIBuilderQuery
-            and signoz/TraceOperator; list panels accept only signoz/BuilderQuery
-            and signoz/AIBuilderQuery.'
+            panels reject signoz/PromQLQuery; heatmap and distribution panels reject
+            signoz/AIBuilderQuery and signoz/TraceOperator; list panels accept only
+            signoz/BuilderQuery and signoz/AIBuilderQuery.'
       required:
       - plugin
       type: object

frontend/jest.config.ts

@@ -11,7 +11,7 @@ const config: Config.InitialOptions = {
 	coverageReporters: ['text', 'cobertura', 'html', 'json-summary'],
 	collectCoverageFrom: ['src/**/*.{ts,tsx}'],
 	moduleFileExtensions: ['ts', 'tsx', 'js', 'json'],
-	modulePathIgnorePatterns: ['dist'],
+	modulePathIgnorePatterns: ['<rootDir>/dist/'],
 	moduleNameMapper: {
 		'\\.(png|jpg|jpeg|gif|svg|webp|avif|ico|bmp|tiff)$':
 			'<rootDir>/__mocks__/fileMock.ts',

frontend/src/lib/uPlotV2/paths/__tests__/variableWidthBars.test.ts

@@ -0,0 +1,139 @@
+import type uPlot from 'uplot';
+
+import { createVariableWidthBarsPathBuilder } from '../variableWidthBars';
+
+class FakePath2D {
+	rects: number[][] = [];
+
+	rect(x: number, y: number, width: number, height: number): void {
+		this.rects.push([x, y, width, height]);
+	}
+}
+
+/** 10 px per unit on both axes; y grows downward from 100. */
+const fakePlot: Partial<uPlot> = {
+	valToPos: (value: number, scaleKey: string): number =>
+		scaleKey === 'x' ? value * 10 : 100 - value * 10,
+	ctx: {} as CanvasRenderingContext2D,
+};
+const plot = fakePlot as uPlot;
+
+type Fills = Map<CanvasRenderingContext2D['fillStyle'], Path2D>;
+
+function fillsOf(paths: ReturnType<uPlot.Series.PathBuilder>): Fills {
+	const fill = paths?.fill;
+	if (!(fill instanceof Map)) {
+		throw new Error('expected a fill per style');
+	}
+	return fill;
+}
+
+function rectsOf(path: Path2D | undefined): number[][] {
+	if (!(path instanceof FakePath2D)) {
+		throw new Error('expected a FakePath2D');
+	}
+	return path.rects;
+}
+
+describe('createVariableWidthBarsPathBuilder', () => {
+	const originalPath2D = globalThis.Path2D;
+
+	beforeAll(() => {
+		Object.defineProperty(globalThis, 'Path2D', {
+			value: FakePath2D,
+			configurable: true,
+		});
+	});
+
+	afterAll(() => {
+		Object.defineProperty(globalThis, 'Path2D', {
+			value: originalPath2D,
+			configurable: true,
+		});
+	});
+
+	function build(
+		pattern: CanvasPattern | null = null,
+	): ReturnType<uPlot.Series.PathBuilder> {
+		return createVariableWidthBarsPathBuilder({
+			getBars: () => [
+				{ x0: 0, x1: 1, y0: 0, y1: 2, hatched: false },
+				{ x0: 1, x1: 4, y0: 0, y1: 5, hatched: false },
+				{ x0: 4, x1: 6, y0: 1, y1: 3, hatched: true },
+			],
+			fill: '#ff0000',
+			hatchedFill: '#ff000066',
+			getHatchPattern: () => pattern,
+			gapPx: 2,
+		})(plot, 1, 0, 0);
+	}
+
+	it('draws each bar at its own width, inset by half the gap', () => {
+		const fills = fillsOf(build());
+
+		expect(rectsOf(fills.get('#ff0000'))).toStrictEqual([
+			[1, 80, 8, 20],
+			[11, 50, 28, 50],
+		]);
+	});
+
+	it('draws hatched bars in their own fill, with the pattern on top', () => {
+		const pattern = {} as CanvasPattern;
+		const fills = fillsOf(build(pattern));
+
+		expect([...fills.keys()]).toStrictEqual(['#ff0000', '#ff000066', pattern]);
+		expect(rectsOf(fills.get(pattern))).toStrictEqual([[41, 70, 18, 20]]);
+	});
+	it('reads a fill callback on every draw', () => {
+		let fill = '#ff0000';
+		const builder = createVariableWidthBarsPathBuilder({
+			getBars: () => [{ x0: 0, x1: 1, y0: 0, y1: 1, hatched: false }],
+			fill: () => fill,
+			hatchedFill: '#00ff00',
+			getHatchPattern: () => null,
+			gapPx: 0,
+		});
+
+		const first = fillsOf(builder(plot, 1, 0, 0));
+		fill = '#0000ff';
+		const second = fillsOf(builder(plot, 1, 0, 0));
+
+		expect([...first.keys()]).toStrictEqual(['#ff0000']);
+		expect([...second.keys()]).toStrictEqual(['#0000ff']);
+	});
+
+	it('keeps solid bars when the hatched fill is the same colour', () => {
+		const fills = fillsOf(
+			createVariableWidthBarsPathBuilder({
+				getBars: () => [
+					{ x0: 0, x1: 1, y0: 0, y1: 1, hatched: false },
+					{ x0: 1, x1: 2, y0: 0, y1: 1, hatched: true },
+				],
+				fill: 'red',
+				hatchedFill: 'red',
+				getHatchPattern: () => null,
+				gapPx: 0,
+			})(plot, 1, 0, 0),
+		);
+
+		expect(rectsOf(fills.get('red'))).toHaveLength(2);
+	});
+
+	it('hatches only overflow bars when both fills are the same colour', () => {
+		const pattern = {} as CanvasPattern;
+		const fills = fillsOf(
+			createVariableWidthBarsPathBuilder({
+				getBars: () => [
+					{ x0: 0, x1: 1, y0: 0, y1: 1, hatched: false },
+					{ x0: 1, x1: 2, y0: 0, y1: 1, hatched: true },
+				],
+				fill: 'red',
+				hatchedFill: 'red',
+				getHatchPattern: () => pattern,
+				gapPx: 0,
+			})(plot, 1, 0, 0),
+		);
+
+		expect(rectsOf(fills.get(pattern))).toStrictEqual([[10, 90, 10, 10]]);
+	});
+});

frontend/src/lib/uPlotV2/paths/variableWidthBars.ts

@@ -0,0 +1,88 @@
+import uPlot from 'uplot';
+
+/** A bar in scale space. Unlike uPlot's own bars, each one carries its own width. */
+export interface VariableWidthBar {
+	x0: number;
+	x1: number;
+	y0: number;
+	y1: number;
+	/** Drawn in `hatchedFill` with the hatch pattern on top. */
+	hatched: boolean;
+}
+
+/** A fill, or one read on every draw (e.g. to dim a series on hover). */
+type BarFill = string | (() => string);
+
+/** Bars narrower than this, in CSS pixels, keep no gap between them. */
+const MIN_WIDTH_FOR_GAP_PX = 3;
+
+/**
+ * Draws `[x0, x1] × [y0, y1]` rects on the `x` and `y` scales. uPlot's bar builder
+ * assumes one width for every bar, which a bucket axis with uneven bounds breaks.
+ *
+ * `getBars` runs on every redraw, so a caller can derive the bars from the plot's
+ * current state (e.g. which series are shown).
+ */
+export function createVariableWidthBarsPathBuilder({
+	getBars,
+	fill,
+	hatchedFill,
+	getHatchPattern,
+	gapPx,
+}: {
+	getBars: (u: uPlot, seriesIdx: number) => VariableWidthBar[];
+	fill: BarFill;
+	hatchedFill: BarFill;
+	getHatchPattern: (ctx: CanvasRenderingContext2D) => CanvasPattern | null;
+	/** Space between neighbouring bars, in CSS pixels. */
+	gapPx: number;
+}): uPlot.Series.PathBuilder {
+	return (u, seriesIdx): uPlot.Series.Paths => {
+		const solidFill = resolveFill(fill);
+		const overflowFill = resolveFill(hatchedFill);
+		const solidPath = new Path2D();
+		// The hatch overlays only overflow bars, so they keep a path of their own even
+		// when one colour fill covers both (a Map keyed by fill holds one path a fill).
+		const hatchedPath = new Path2D();
+		const isSharedFill = overflowFill === solidFill;
+		const inset = (gapPx * uPlot.pxRatio) / 2;
+		const minWidthForGap = MIN_WIDTH_FOR_GAP_PX * uPlot.pxRatio;
+		let hasHatched = false;
+
+		getBars(u, seriesIdx).forEach((bar) => {
+			const left = u.valToPos(bar.x0, 'x', true);
+			const right = u.valToPos(bar.x1, 'x', true);
+			const top = u.valToPos(bar.y1, 'y', true);
+			const bottom = u.valToPos(bar.y0, 'y', true);
+			const width = right - left;
+			const gap = width > minWidthForGap ? inset : 0;
+			const rect = [left + gap, top, width - 2 * gap, bottom - top] as const;
+			if (!bar.hatched || isSharedFill) {
+				solidPath.rect(...rect);
+			}
+			if (bar.hatched) {
+				hatchedPath.rect(...rect);
+				hasHatched = true;
+			}
+		});
+
+		const fills = new Map<CanvasRenderingContext2D['fillStyle'], Path2D>([
+			[solidFill, solidPath],
+		]);
+		if (hasHatched) {
+			if (!isSharedFill) {
+				fills.set(overflowFill, hatchedPath);
+			}
+			const pattern = getHatchPattern(u.ctx);
+			if (pattern) {
+				fills.set(pattern, hatchedPath);
+			}
+		}
+
+		return { stroke: null, fill: fills, clip: null, band: null, flags: 0 };
+	};
+}
+
+function resolveFill(fill: BarFill): string {
+	return typeof fill === 'function' ? fill() : fill;
+}

frontend/src/lib/visualization/charts/Distribution/Distribution.module.scss

@@ -0,0 +1,5 @@
+.notice {
+	padding: var(--spacing-2) var(--spacing-4);
+	font-size: var(--font-size-xs);
+	color: var(--muted-foreground);
+}

frontend/src/lib/visualization/charts/Distribution/Distribution.tsx

@@ -0,0 +1,279 @@
+import { useCallback, useMemo } from 'react';
+import Legend from 'lib/uPlotV2/components/Legend/Legend';
+import {
+	LegendPosition,
+	type TooltipRenderArgs,
+} from 'lib/uPlotV2/components/types';
+import type { LegendItem } from 'lib/uPlotV2/config/types';
+import { StackMode } from 'lib/uPlotV2/config/types';
+import ChartWrapper from 'lib/visualization/charts/ChartWrapper/ChartWrapper';
+import { resolveBoundaryPrecision } from 'lib/visualization/charts/Heatmap/utils';
+import { DistributionChartProps } from 'lib/visualization/charts/types';
+import { useLegendVisibility } from 'lib/visualization/hooks/useLegendVisibility';
+import type { LegendLayout } from 'lib/visualization/layout/ChartLayout/ChartLayout';
+
+import { resolveOtherColor, resolveSeriesColor } from './colors';
+import DistributionTooltip from './components/DistributionTooltip/DistributionTooltip';
+import { buildDistributionConfig } from './config';
+import {
+	clampDistributionXAxis,
+	cropDistributionXAxis,
+	resolveDistributionBars,
+	resolveDistributionXAxis,
+	sumVisibleCounts,
+} from './layout';
+import { computeDistributionPercentiles } from './percentiles';
+import { groupIntoOther, resolveMaxDrawnGroups } from './topGroups';
+import { DistributionYScale } from './types';
+import { useDistributionBarClick } from './useDistributionBarClick';
+
+import styles from './Distribution.module.scss';
+import { createBoundFormatter, prepareDistributionChartData } from './utils';
+
+/** Rough share of the panel width the plot gets, for fitting side-by-side bars. */
+const PLOT_SHARE = 0.9;
+const PLOT_SHARE_WITH_RIGHT_LEGEND = 0.65;
+/** Vertical space the Other notice takes out of the container. */
+const NOTICE_HEIGHT = 20;
+const NO_PERCENTILES: readonly number[] = Object.freeze([]);
+
+export default function Distribution({
+	id,
+	buckets,
+	series,
+	width,
+	height,
+	isDarkMode,
+	xMin,
+	xMax,
+	yScale = DistributionYScale.Linear,
+	stack = StackMode.Normal,
+	xAxisUnit,
+	decimalPrecision,
+	customColors,
+	percentiles = NO_PERCENTILES,
+	onBarClick,
+	showLegend = true,
+	legendPosition = LegendPosition.BOTTOM,
+	showTooltip = true,
+	canPinTooltip = false,
+	renderTooltipFooter,
+	tooltipPortalRoot,
+	layoutChildren,
+	'data-testid': testId,
+}: DistributionChartProps): JSX.Element {
+	const labels = useMemo(() => series.map((entry) => entry.label), [series]);
+	const counts = useMemo(() => series.map((entry) => entry.counts), [series]);
+
+	const { visibleKeys, focusedSeriesIndex, onLegendAction } =
+		useLegendVisibility({ keys: labels, indexOffset: 1, id });
+
+	const visible = useMemo(
+		() => labels.map((label) => visibleKeys.includes(label)),
+		[labels, visibleKeys],
+	);
+
+	const colors = useMemo(
+		() =>
+			labels.map((label) => resolveSeriesColor(label, isDarkMode, customColors)),
+		[labels, isDarkMode, customColors],
+	);
+
+	const { xAxis, totals } = useMemo(() => {
+		const full = resolveDistributionXAxis(buckets);
+		const visibleTotals = sumVisibleCounts(counts, visible, full.rows.length);
+		// An explicit max may reach past the last occupied bucket; only auto-crop without one.
+		const fitted =
+			xMax === undefined ? cropDistributionXAxis(full, visibleTotals) : full;
+		return {
+			xAxis: clampDistributionXAxis(fitted, xMin, xMax),
+			totals: visibleTotals,
+		};
+	}, [buckets, xMin, xMax, counts, visible]);
+
+	// Over the visible groups combined, so a legend toggle moves them without a refetch.
+	const markers = useMemo(
+		() => computeDistributionPercentiles({ xAxis, totals, percentiles }),
+		[xAxis, totals, percentiles],
+	);
+
+	const isLogY =
+		yScale === DistributionYScale.Log && stack !== StackMode.Percent;
+
+	// The legend lists every group; the plot draws the largest and sums the rest into
+	// Other, so a toggle re-ranks without a refetch.
+	const drawn = useMemo(
+		() =>
+			groupIntoOther({
+				labels,
+				counts,
+				colors,
+				visible,
+				maxGroups: resolveMaxDrawnGroups({
+					stack,
+					xAxis,
+					plotWidth:
+						width *
+						(legendPosition === LegendPosition.RIGHT
+							? PLOT_SHARE_WITH_RIGHT_LEGEND
+							: PLOT_SHARE),
+				}),
+				otherColor: resolveOtherColor(isDarkMode),
+			}),
+		[
+			labels,
+			counts,
+			colors,
+			visible,
+			stack,
+			xAxis,
+			width,
+			legendPosition,
+			isDarkMode,
+		],
+	);
+
+	const layout = useMemo(
+		() =>
+			resolveDistributionBars({
+				xAxis,
+				counts: drawn.counts,
+				stack,
+				isLogY,
+			}),
+		[xAxis, drawn, stack, isLogY],
+	);
+
+	const boundaryPrecision = useMemo(
+		() =>
+			resolveBoundaryPrecision({
+				yAxis: xAxis,
+				yAxisUnit: xAxisUnit,
+				decimalPrecision,
+			}),
+		[xAxis, xAxisUnit, decimalPrecision],
+	);
+
+	const formatBound = useMemo(
+		() => createBoundFormatter(xAxisUnit, boundaryPrecision),
+		[xAxisUnit, boundaryPrecision],
+	);
+
+	const config = useMemo(
+		() =>
+			buildDistributionConfig({
+				id,
+				xAxis,
+				layout,
+				labels: drawn.labels,
+				colors: drawn.colors,
+				stack,
+				isLogY,
+				isDarkMode,
+				markers,
+				xAxisUnit,
+				decimalPrecision: boundaryPrecision,
+			}),
+		[
+			id,
+			xAxis,
+			layout,
+			drawn,
+			stack,
+			isLogY,
+			isDarkMode,
+			markers,
+			xAxisUnit,
+			boundaryPrecision,
+		],
+	);
+
+	const renderTooltip = useCallback(
+		(args: TooltipRenderArgs): React.ReactNode => (
+			<DistributionTooltip
+				uPlotInstance={args.uPlotInstance}
+				isPinned={args.isPinned}
+				dismiss={args.dismiss}
+				xAxis={xAxis}
+				layout={layout}
+				labels={drawn.labels}
+				colors={drawn.colors}
+				counts={drawn.counts}
+				formatBound={formatBound}
+				renderTooltipFooter={renderTooltipFooter}
+			/>
+		),
+		[xAxis, layout, drawn, formatBound, renderTooltipFooter],
+	);
+
+	const handleClick = useDistributionBarClick({
+		xAxis,
+		layout,
+		drawn,
+		series,
+		onBarClick,
+	});
+
+	const data = useMemo(
+		() => prepareDistributionChartData(xAxis, drawn.counts),
+		[xAxis, drawn],
+	);
+
+	const legendItems = useMemo<LegendItem[]>(
+		() =>
+			labels.map((label, index) => ({
+				seriesIndex: index + 1,
+				label,
+				color: colors[index],
+				show: visible[index],
+			})),
+		[labels, colors, visible],
+	);
+
+	const groupLegend = useCallback(
+		({ averageLegendWidth, showSearch }: LegendLayout): React.ReactNode => (
+			<Legend
+				items={legendItems}
+				position={legendPosition}
+				averageLegendWidth={averageLegendWidth}
+				showSearch={showSearch}
+				itemLabel="groups"
+				focusedSeriesIndex={focusedSeriesIndex}
+				onAction={onLegendAction}
+			/>
+		),
+		[legendItems, legendPosition, focusedSeriesIndex, onLegendAction],
+	);
+
+	return (
+		<ChartWrapper
+			config={config}
+			data={data}
+			width={width}
+			height={
+				drawn.otherGroupCount > 0 ? Math.max(0, height - NOTICE_HEIGHT) : height
+			}
+			legendConfig={{ position: legendPosition }}
+			showLegend={showLegend}
+			customLegend={groupLegend}
+			legendLabels={labels}
+			showTooltip={showTooltip}
+			canPinTooltip={canPinTooltip}
+			decimalPrecision={decimalPrecision}
+			customTooltip={renderTooltip}
+			onClick={handleClick}
+			contentFooter={
+				drawn.otherGroupCount > 0 && (
+					<div className={styles.notice} data-testid="distribution-other-notice">
+						Showing top {drawn.labels.length - 1} of {drawn.visibleGroupCount} groups;
+						the rest are summed into Other.
+					</div>
+				)
+			}
+			renderTooltipFooter={renderTooltipFooter}
+			tooltipPortalRoot={tooltipPortalRoot}
+			layoutChildren={layoutChildren}
+			data-testid={testId}
+		/>
+	);
+}

frontend/src/lib/visualization/charts/Distribution/__tests__/Distribution.test.tsx

@@ -0,0 +1,115 @@
+import type React from 'react';
+import type { LegendItem } from 'lib/uPlotV2/config/types';
+import { render, screen, userEvent } from 'tests/test-utils';
+
+import Distribution from '../Distribution';
+import type { DistributionSeries } from '../types';
+
+// The shared Legend virtualises its items; render them all so they are queryable.
+jest.mock('react-virtuoso', () => ({
+	VirtuosoGrid: ({
+		data,
+		itemContent,
+	}: {
+		data: LegendItem[];
+		itemContent: (index: number, item: LegendItem) => React.ReactNode;
+	}): JSX.Element => (
+		<div>
+			{data.map((item, index) => (
+				<div key={item.seriesIndex}>{itemContent(index, item)}</div>
+			))}
+		</div>
+	),
+}));
+
+const BUCKETS = [5, 10, 100, 1000];
+
+const SERIES: DistributionSeries[] = [
+	{ label: 'service.name=cart', counts: [3, 40, 12, 1, 0] },
+	{ label: 'service.name=checkout', counts: [1, 10, 30, 6, 2] },
+];
+
+function renderDistribution(
+	props: Partial<React.ComponentProps<typeof Distribution>> = {},
+): ReturnType<typeof render> {
+	return render(
+		<Distribution
+			id="panel-1"
+			buckets={BUCKETS}
+			series={SERIES}
+			width={800}
+			height={400}
+			isDarkMode
+			data-testid="distribution"
+			{...props}
+		/>,
+	);
+}
+
+describe('Distribution', () => {
+	// Legend items count from 1, as uPlot's data series do.
+	const CART = 1;
+	const CHECKOUT = 2;
+
+	// The selection persists under the panel id, which every case here shares.
+	beforeEach(() => localStorage.clear());
+
+	function legendItem(seriesIndex: number): HTMLElement {
+		return screen.getByTestId(`legend-item-${seriesIndex}`);
+	}
+
+	it('renders the plot container', () => {
+		renderDistribution();
+
+		expect(screen.getByTestId('distribution')).toBeInTheDocument();
+	});
+
+	it('lists every group in the legend, all shown', () => {
+		renderDistribution();
+
+		expect(legendItem(CART)).toHaveAttribute('aria-checked', 'true');
+		expect(legendItem(CHECKOUT)).toHaveAttribute('aria-checked', 'true');
+	});
+
+	it('isolates a group when its row is clicked', async () => {
+		const user = userEvent.setup({ pointerEventsCheck: 0 });
+		renderDistribution();
+
+		await user.click(legendItem(CART));
+
+		expect(legendItem(CART)).toHaveAttribute('aria-checked', 'true');
+		expect(legendItem(CHECKOUT)).toHaveAttribute('aria-checked', 'false');
+	});
+
+	it('hides only that group when its marker is clicked', async () => {
+		const user = userEvent.setup({ pointerEventsCheck: 0 });
+		renderDistribution();
+
+		await user.click(screen.getByTestId(`legend-marker-${CHECKOUT}`));
+
+		expect(legendItem(CHECKOUT)).toHaveAttribute('aria-checked', 'false');
+		expect(legendItem(CART)).toHaveAttribute('aria-checked', 'true');
+	});
+	it('sums groups past the stacked cap into Other, with a notice', () => {
+		renderDistribution({
+			series: Array.from({ length: 12 }, (_, index) => ({
+				label: `group-${index}`,
+				counts: [index, 1, 1, 0, 0],
+			})),
+		});
+
+		expect(screen.getByTestId('distribution-other-notice')).toHaveTextContent(
+			'Showing top 9 of 12 groups; the rest are summed into Other.',
+		);
+		// The legend still lists every group, so any can be isolated.
+		expect(legendItem(1)).toHaveAttribute('aria-label', 'group-0');
+	});
+
+	it('shows no notice when every group fits', () => {
+		renderDistribution();
+
+		expect(
+			screen.queryByTestId('distribution-other-notice'),
+		).not.toBeInTheDocument();
+	});
+});

frontend/src/lib/visualization/charts/Distribution/__tests__/config.test.ts

@@ -0,0 +1,126 @@
+import { StackMode } from 'lib/uPlotV2/config/types';
+import type uPlot from 'uplot';
+
+import { resolveDistributionBars, resolveDistributionXAxis } from '../layout';
+import { buildDistributionConfig } from '../config';
+
+// Buckets ≤ 10, (10, 20], (20, 40], > 40 in slots [0, 1] … [3, 4]. Only (10, 20] is occupied.
+const xAxis = resolveDistributionXAxis([10, 20, 40]);
+const counts = [
+	[0, 4, 0, 0],
+	[0, 6, 0, 0],
+];
+
+function setCursorHook(drawnCounts = counts): (u: uPlot) => void {
+	const config = buildDistributionConfig({
+		id: 'panel-1',
+		xAxis,
+		layout: resolveDistributionBars({
+			xAxis,
+			counts: drawnCounts,
+			stack: StackMode.Normal,
+			isLogY: false,
+		}),
+		labels: drawnCounts.map((_, index) => `group-${index}`),
+		colors: drawnCounts.map(() => '#ff0000'),
+		stack: StackMode.Normal,
+		isLogY: false,
+		isDarkMode: true,
+		markers: [],
+	}).getConfig();
+	const [hook] = config.hooks?.setCursor ?? [];
+	return hook as (u: uPlot) => void;
+}
+
+/** Pixels are values, so the cursor sits at `(left, top)` in scale space. */
+function plotAt(
+	left: number,
+	top: number,
+): { u: uPlot; setSeries: jest.Mock; redraw: jest.Mock } {
+	const setSeries = jest.fn();
+	const redraw = jest.fn();
+	const plot: Partial<uPlot> = {
+		cursor: { left, top },
+		posToVal: (position: number) => position,
+		setSeries,
+		redraw,
+	};
+	return { u: plot as uPlot, setSeries, redraw };
+}
+
+describe('buildDistributionConfig cursor', () => {
+	it('turns off drag-to-zoom', () => {
+		const config = buildDistributionConfig({
+			id: 'panel-1',
+			xAxis,
+			layout: resolveDistributionBars({
+				xAxis,
+				counts,
+				stack: StackMode.Normal,
+				isLogY: false,
+			}),
+			labels: ['group-0', 'group-1'],
+			colors: ['#ff0000', '#ff0000'],
+			stack: StackMode.Normal,
+			isLogY: false,
+			isDarkMode: true,
+			markers: [],
+		}).getConfig();
+
+		expect(config.cursor?.drag).toMatchObject({ x: false, y: false });
+	});
+});
+
+describe('buildDistributionConfig setCursor', () => {
+	// TooltipPlugin only shows a tooltip for a focused series.
+	it('focuses the group under the cursor, 1-based as uPlot counts series', () => {
+		const { u, setSeries, redraw } = plotAt(1.5, 8);
+
+		setCursorHook()(u);
+
+		expect(setSeries).toHaveBeenCalledWith(2, { focus: true });
+		expect(redraw).toHaveBeenCalledWith(true, false);
+	});
+
+	it('focuses the nearest group above the stack, dimming the rest', () => {
+		const { u, setSeries, redraw } = plotAt(1.5, 50);
+
+		setCursorHook()(u);
+
+		expect(setSeries).toHaveBeenCalledWith(2, { focus: true });
+		expect(redraw).toHaveBeenCalledWith(true, false);
+	});
+
+	it('keeps a tooltip over an empty bucket without dimming any group', () => {
+		const hook = setCursorHook();
+		const { u, setSeries, redraw } = plotAt(1.5, 8);
+		hook(u);
+		redraw.mockClear();
+
+		u.cursor.left = 2.5;
+		u.cursor.top = 1;
+		hook(u);
+
+		expect(setSeries).toHaveBeenLastCalledWith(1, { focus: true });
+		expect(redraw).toHaveBeenCalledWith(true, false);
+	});
+
+	it('focuses nothing off the plot', () => {
+		const hook = setCursorHook();
+		const { u, setSeries } = plotAt(1.5, 8);
+		hook(u);
+
+		u.cursor.left = -1;
+		hook(u);
+
+		expect(setSeries).toHaveBeenLastCalledWith(null, { focus: true });
+	});
+
+	it('focuses nothing over an empty bucket when every group is hidden', () => {
+		const { u, setSeries } = plotAt(2.5, 1);
+
+		setCursorHook([])(u);
+
+		expect(setSeries).not.toHaveBeenCalled();
+	});
+});

frontend/src/lib/visualization/charts/Distribution/__tests__/drawPercentileMarkers.test.ts

@@ -0,0 +1,58 @@
+import {
+	layoutMarkerLabels,
+	resolveHoveredMarker,
+} from '../drawPercentileMarkers';
+
+describe('resolveHoveredMarker', () => {
+	const areas = [
+		{
+			x: 100,
+			badges: [
+				{ left: 92, right: 108, top: 0, bottom: 16 },
+				{ left: 92, right: 108, top: 184, bottom: 200 },
+			],
+		},
+		{
+			x: 120,
+			badges: [{ left: 112, right: 128, top: 18, bottom: 34 }],
+		},
+	];
+
+	it('picks the line nearest x within the tolerance', () => {
+		expect(resolveHoveredMarker(areas, 103, 100, 4)).toBe(0);
+		expect(resolveHoveredMarker(areas, 117, 100, 4)).toBe(1);
+		expect(resolveHoveredMarker(areas, 110, 100, 4)).toBeNull();
+	});
+
+	it('picks the marker whose badge is under the cursor', () => {
+		expect(resolveHoveredMarker(areas, 107, 190, 4)).toBe(0);
+		expect(resolveHoveredMarker(areas, 126, 20, 4)).toBe(1);
+	});
+});
+
+describe('layoutMarkerLabels', () => {
+	it('keeps labels that fit on the first row', () => {
+		expect(
+			layoutMarkerLabels(
+				[
+					{ x: 0, width: 20 },
+					{ x: 40, width: 20 },
+				],
+				4,
+			),
+		).toStrictEqual([0, 0]);
+	});
+
+	it('drops a label that would overlap to the next free row', () => {
+		expect(
+			layoutMarkerLabels(
+				[
+					{ x: 30, width: 20 },
+					{ x: 0, width: 20 },
+					{ x: 10, width: 20 },
+				],
+				4,
+			),
+		).toStrictEqual([0, 0, 1]);
+	});
+});

frontend/src/lib/visualization/charts/Distribution/__tests__/layout.test.ts

@@ -0,0 +1,286 @@
+import { StackMode } from 'lib/uPlotV2/config/types';
+
+import {
+	clampDistributionXAxis,
+	cropDistributionXAxis,
+	LOG_Y_BASE,
+	resolveDistributionBars,
+	resolveDistributionXAxis,
+	resolveNearestSeries,
+	sumVisibleCounts,
+	thinLabelledSplits,
+} from '../layout';
+
+function widths(edges: number[]): number[] {
+	return edges.slice(1).map((edge, index) => edge - edges[index]);
+}
+
+describe('resolveDistributionXAxis', () => {
+	it('lays N bounds out as N + 1 buckets, overflow last', () => {
+		const axis = resolveDistributionXAxis([10, 20, 30]);
+
+		expect(axis.rows).toHaveLength(4);
+		expect(axis.rows[0].isUnderflow).toBe(true);
+		expect(axis.rows[3]).toMatchObject({ lower: 30, isOverflow: true });
+		expect(axis.edges).toHaveLength(5);
+	});
+
+	it('gives every bucket the same width, ticks on the bounds', () => {
+		const axis = resolveDistributionXAxis([0, 5, 10, 25, 1000]);
+
+		expect(widths(axis.edges)).toStrictEqual([1, 1, 1, 1, 1, 1]);
+		expect(axis.splits).toStrictEqual([1, 2, 3, 4, 5]);
+		expect(axis.overflowSplit).toBe(6);
+		expect(axis.toBucketValue(3.5)).toBe(17.5);
+	});
+});
+
+describe('cropDistributionXAxis', () => {
+	it('stops one bucket past the last occupied one', () => {
+		const axis = resolveDistributionXAxis([1, 2, 3, 4]);
+
+		const cropped = cropDistributionXAxis(axis, [1, 5, 0, 0, 0]);
+
+		expect(cropped.max).toBe(3);
+		expect(cropped.overflowSplit).toBeNull();
+	});
+});
+
+describe('clampDistributionXAxis', () => {
+	// Buckets ≤ 10, (10, 20], (20, 40], (40, 80], > 80 in slots [0, 1] … [4, 5].
+	const axis = resolveDistributionXAxis([10, 20, 40, 80]);
+
+	it('keeps every bucket without a range', () => {
+		expect(clampDistributionXAxis(axis)).toStrictEqual(axis);
+	});
+
+	it('hides buckets wholly outside the range, keeping straddling ones whole', () => {
+		const clamped = clampDistributionXAxis(axis, 20, 50);
+
+		expect([clamped.min, clamped.max]).toStrictEqual([2, 4]);
+		expect(clamped.overflowSplit).toBeNull();
+	});
+
+	it('keeps the overflow tick while the overflow bucket shows', () => {
+		const clamped = clampDistributionXAxis(axis, 15);
+
+		expect([clamped.min, clamped.max]).toStrictEqual([1, 5]);
+		expect(clamped.overflowSplit).toBe(5);
+	});
+
+	it('keeps one bucket when the range misses them all', () => {
+		const clamped = clampDistributionXAxis(axis, 1000);
+
+		expect([clamped.min, clamped.max]).toStrictEqual([4, 5]);
+	});
+
+	it('narrows an already cropped axis, never widening it', () => {
+		const cropped = cropDistributionXAxis(axis, [1, 5, 0, 0, 0]);
+
+		expect(clampDistributionXAxis(cropped, 15).max).toBe(cropped.max);
+	});
+});
+
+describe('sumVisibleCounts', () => {
+	it('adds only the visible series', () => {
+		expect(
+			sumVisibleCounts(
+				[
+					[1, 2],
+					[10, 20],
+					[100, 200],
+				],
+				[true, false, true],
+				2,
+			),
+		).toStrictEqual([101, 202]);
+	});
+});
+
+describe('resolveDistributionBars', () => {
+	const xAxis = resolveDistributionXAxis([1, 2]);
+	const counts = [
+		[4, 6, 0],
+		[1, 3, 2],
+	];
+
+	it('sizes the count axis by the buckets left in the window', () => {
+		// Buckets ≤ 1, (1, 2], > 2; a max of 1 keeps only the first.
+		const { yMax } = resolveDistributionBars({
+			xAxis: clampDistributionXAxis(xAxis, undefined, 1),
+			counts: [[4, 1000, 0]],
+			stack: StackMode.Normal,
+			isLogY: false,
+		});
+
+		expect(yMax).toBe(4);
+	});
+
+	it('stacks series in each bucket under normal', () => {
+		const { rects, yMax } = resolveDistributionBars({
+			xAxis,
+			counts,
+			stack: StackMode.Normal,
+			isLogY: false,
+		});
+
+		expect(rects[0].map(({ y0, y1 }) => [y0, y1])).toStrictEqual([
+			[0, 4],
+			[0, 6],
+		]);
+		expect(rects[1].map(({ y0, y1 }) => [y0, y1])).toStrictEqual([
+			[4, 5],
+			[6, 9],
+			[0, 2],
+		]);
+		expect(yMax).toBe(9);
+	});
+
+	it('marks the overflow bucket hatched', () => {
+		const { rects } = resolveDistributionBars({
+			xAxis,
+			counts,
+			stack: StackMode.Normal,
+			isLogY: false,
+		});
+
+		expect(rects[1].map(({ hatched }) => hatched)).toStrictEqual([
+			false,
+			false,
+			true,
+		]);
+	});
+
+	it('stacks shares of each bucket under percent', () => {
+		const { rects, yMax } = resolveDistributionBars({
+			xAxis,
+			counts,
+			stack: StackMode.Percent,
+			isLogY: false,
+		});
+
+		expect(rects[0][0]).toMatchObject({ y0: 0, y1: 80 });
+		expect(rects[1][0]).toMatchObject({ y0: 80, y1: 100 });
+		expect(yMax).toBe(100);
+	});
+
+	it('splits the bucket width between series under none', () => {
+		const { rects, yMax } = resolveDistributionBars({
+			xAxis,
+			counts,
+			stack: StackMode.None,
+			isLogY: false,
+		});
+
+		expect(rects[0][0]).toMatchObject({ x0: 0, x1: 0.5, y0: 0, y1: 4 });
+		expect(rects[1][0]).toMatchObject({ x0: 0.5, x1: 1, y0: 0, y1: 1 });
+		expect(yMax).toBe(6);
+	});
+
+	it('starts bars at the log base and skips zero counts', () => {
+		const { rects } = resolveDistributionBars({
+			xAxis,
+			counts,
+			stack: StackMode.Normal,
+			isLogY: true,
+		});
+
+		expect(rects[0].map(({ y0 }) => y0)).toStrictEqual([LOG_Y_BASE, LOG_Y_BASE]);
+		expect(rects[0].map(({ bucketIndex }) => bucketIndex)).toStrictEqual([0, 1]);
+	});
+
+	it('skips bars whose top stays under the log base, never inverting one', () => {
+		const fractional = [
+			[0.5, 3, 0],
+			[0.25, 0.5, 2],
+		];
+		const stacked = resolveDistributionBars({
+			xAxis,
+			counts: fractional,
+			stack: StackMode.Normal,
+			isLogY: true,
+		});
+		const sideBySide = resolveDistributionBars({
+			xAxis,
+			counts: fractional,
+			stack: StackMode.None,
+			isLogY: true,
+		});
+
+		expect(
+			stacked.rects.map((rects) => rects.map(({ y0, y1 }) => [y0, y1])),
+		).toStrictEqual([
+			[[LOG_Y_BASE, 3]],
+			[
+				[3, 3.5],
+				[LOG_Y_BASE, 2],
+			],
+		]);
+		expect(
+			sideBySide.rects.map((rects) => rects.map(({ bucketIndex }) => bucketIndex)),
+		).toStrictEqual([[1], [2]]);
+	});
+});
+
+describe('thinLabelledSplits', () => {
+	it('keeps labels that clear each other by the gap', () => {
+		expect(
+			thinLabelledSplits({
+				positions: [0, 50, 100],
+				widths: [20, 20, 20],
+				gap: 10,
+			}),
+		).toStrictEqual([0, 1, 2]);
+	});
+
+	it('drops a wide label that would touch its neighbour, keeping the rightmost', () => {
+		// 16.67 mins-wide labels 60 px apart: each needs 70 px of centre distance.
+		expect(
+			thinLabelledSplits({
+				positions: [0, 60, 120, 180],
+				widths: [60, 60, 60, 60],
+				gap: 10,
+			}),
+		).toStrictEqual([1, 3]);
+	});
+});
+
+describe('resolveNearestSeries', () => {
+	// Buckets ≤ 10, (10, 20], (20, 40], > 40 in slots [0, 1] … [3, 4].
+	const xAxis = resolveDistributionXAxis([10, 20, 40]);
+	const counts = [
+		[0, 4, 0, 0],
+		[0, 6, 0, 0],
+	];
+	const stacked = resolveDistributionBars({
+		xAxis,
+		counts,
+		stack: StackMode.Normal,
+		isLogY: false,
+	});
+
+	it('names the group whose bar is under the point', () => {
+		expect(resolveNearestSeries(stacked, 1, 1.5, 2)).toBe(0);
+		expect(resolveNearestSeries(stacked, 1, 1.5, 8)).toBe(1);
+	});
+
+	it('takes the vertically nearest group off the bars, as a bar chart does', () => {
+		expect(resolveNearestSeries(stacked, 1, 1.5, 50)).toBe(1);
+	});
+
+	it('is null over an empty bucket', () => {
+		expect(resolveNearestSeries(stacked, 2, 2.5, 1)).toBeNull();
+	});
+
+	it('picks the sub-bar under the cursor side by side', () => {
+		const sideBySide = resolveDistributionBars({
+			xAxis,
+			counts,
+			stack: StackMode.None,
+			isLogY: false,
+		});
+
+		expect(resolveNearestSeries(sideBySide, 1, 1.25, 50)).toBe(0);
+		expect(resolveNearestSeries(sideBySide, 1, 1.75, 1)).toBe(1);
+	});
+});

frontend/src/lib/visualization/charts/Distribution/__tests__/percentiles.test.ts

@@ -0,0 +1,97 @@
+import { resolveDistributionXAxis } from '../layout';
+import {
+	computeDistributionPercentiles,
+	formatPercentileBadge,
+	formatPercentileName,
+	formatPercentileValue,
+	groupPercentileMarkers,
+} from '../percentiles';
+
+// Buckets ≤ 10, (10, 20], (20, 40], > 40 in slots [0, 1] … [3, 4].
+const xAxis = resolveDistributionXAxis([10, 20, 40]);
+
+describe('computeDistributionPercentiles', () => {
+	it('interpolates inside the bucket holding the rank, as histogram_quantile does', () => {
+		const markers = computeDistributionPercentiles({
+			xAxis,
+			totals: [10, 20, 10, 0],
+			percentiles: [50, 90],
+		});
+
+		expect(markers.map(({ value }) => value)).toStrictEqual([15, 32]);
+		expect(markers.every(({ isOverflow }) => !isOverflow)).toBe(true);
+	});
+
+	it('places the marker the same fraction across the bucket on the axis', () => {
+		const [p50] = computeDistributionPercentiles({
+			xAxis,
+			totals: [10, 20, 10, 0],
+			percentiles: [50],
+		});
+
+		expect(p50.axisValue).toBe(1.5);
+	});
+
+	it('starts the lowest bucket at zero', () => {
+		const [p10] = computeDistributionPercentiles({
+			xAxis,
+			totals: [10, 20, 10, 0],
+			percentiles: [10],
+		});
+
+		expect(p10.value).toBe(4);
+	});
+
+	it('reports a percentile in overflow as above the last bound, at its left edge', () => {
+		const [p99] = computeDistributionPercentiles({
+			xAxis,
+			totals: [0, 0, 10, 10],
+			percentiles: [99],
+		});
+
+		expect(p99).toMatchObject({ value: 40, axisValue: 3, isOverflow: true });
+	});
+
+	it('marks nothing when every count is zero', () => {
+		expect(
+			computeDistributionPercentiles({
+				xAxis,
+				totals: [0, 0, 0, 0],
+				percentiles: [50],
+			}),
+		).toStrictEqual([]);
+	});
+});
+
+describe('formatPercentileName', () => {
+	it('keeps fractional percentile names short', () => {
+		expect(formatPercentileName(99.9)).toBe('p99.9');
+		expect(formatPercentileName(50)).toBe('p50');
+	});
+});
+
+describe('percentile marker groups', () => {
+	const formatBound = (value: number): string => `${value} ms`;
+	const p50 = { percentile: 50, value: 15, axisValue: 1.5, isOverflow: false };
+	const p99 = { percentile: 99, value: 40, axisValue: 3, isOverflow: true };
+	const p90 = { percentile: 90, value: 40, axisValue: 3, isOverflow: true };
+
+	it('groups markers on the same spot, lowest percentile first', () => {
+		expect(groupPercentileMarkers([p50, p99, p90])).toStrictEqual([
+			[p50],
+			[p90, p99],
+		]);
+	});
+
+	it('names a group by its lowest percentile', () => {
+		expect(formatPercentileBadge([p50])).toBe('p50');
+		expect(formatPercentileBadge([p90, p99])).toBe('p90+');
+	});
+
+	it('shows the estimate, or the overflow bound once for the group', () => {
+		expect(formatPercentileValue([p50], formatBound)).toBe('p50 ≈ 15 ms');
+		expect(formatPercentileValue([p90, p99], formatBound)).toBe(
+			'p90, p99 > 40 ms',
+		);
+	});
+});

frontend/src/lib/visualization/charts/Distribution/__tests__/topGroups.test.ts

@@ -0,0 +1,126 @@
+import { StackMode } from 'lib/uPlotV2/config/types';
+
+import { resolveDistributionXAxis } from '../layout';
+import {
+	groupIntoOther,
+	resolveClickedGroup,
+	MAX_STACKED_GROUPS,
+	OTHER_GROUP_LABEL,
+	resolveMaxDrawnGroups,
+} from '../topGroups';
+
+describe('resolveMaxDrawnGroups', () => {
+	// Four equal buckets plus underflow and overflow: six slots of one unit each.
+	const xAxis = resolveDistributionXAxis([1, 2, 3, 4, 5]);
+
+	it('caps stacked and percent at the fixed limit', () => {
+		expect(
+			resolveMaxDrawnGroups({ stack: StackMode.Normal, xAxis, plotWidth: 60 }),
+		).toBe(MAX_STACKED_GROUPS);
+		expect(
+			resolveMaxDrawnGroups({ stack: StackMode.Percent, xAxis, plotWidth: 60 }),
+		).toBe(MAX_STACKED_GROUPS);
+	});
+
+	it('fits side by side so the narrowest bar stays 3 px wide', () => {
+		// 120 px over six slots: 20 px a bucket, six 3 px bars.
+		expect(
+			resolveMaxDrawnGroups({ stack: StackMode.None, xAxis, plotWidth: 120 }),
+		).toBe(6);
+		expect(
+			resolveMaxDrawnGroups({ stack: StackMode.None, xAxis, plotWidth: 6 }),
+		).toBe(1);
+	});
+});
+
+describe('groupIntoOther', () => {
+	const args = {
+		labels: ['a', 'b', 'c', 'd'],
+		counts: [
+			[1, 1],
+			[5, 5],
+			[2, 0],
+			[3, 3],
+		],
+		colors: ['#a', '#b', '#c', '#d'],
+		visible: [true, true, true, true],
+		otherColor: '#999',
+	};
+
+	it('draws every visible group when they fit', () => {
+		const drawn = groupIntoOther({ ...args, maxGroups: 4 });
+
+		expect(drawn.labels).toStrictEqual(['a', 'b', 'c', 'd']);
+		expect(drawn.otherGroupCount).toBe(0);
+	});
+
+	it('keeps the largest, in legend order, and sums the rest exactly', () => {
+		const drawn = groupIntoOther({ ...args, maxGroups: 3 });
+
+		expect(drawn.labels).toStrictEqual(['b', 'd', OTHER_GROUP_LABEL]);
+		expect(drawn.sourceIndexes).toStrictEqual([1, 3, null]);
+		expect(drawn.counts[2]).toStrictEqual([3, 1]);
+		expect(drawn.colors[2]).toBe('#999');
+		expect(drawn).toMatchObject({ otherGroupCount: 2, visibleGroupCount: 4 });
+	});
+
+	it('re-ranks without hidden groups, which never reach Other', () => {
+		const drawn = groupIntoOther({
+			...args,
+			visible: [true, false, true, true],
+			maxGroups: 2,
+		});
+
+		expect(drawn.labels).toStrictEqual(['d', OTHER_GROUP_LABEL]);
+		expect(drawn.sourceIndexes).toStrictEqual([3, null]);
+		expect(drawn.counts[1]).toStrictEqual([3, 1]);
+		expect(drawn.visibleGroupCount).toBe(3);
+	});
+});
+
+describe('resolveClickedGroup', () => {
+	const series = ['a', 'b', 'c'].map((label) => ({
+		label,
+		counts: [label === 'a' ? 5 : 1],
+	}));
+	const drawn = groupIntoOther({
+		labels: ['a', 'b', 'c'],
+		counts: series.map(({ counts }) => counts),
+		colors: ['#a', '#b', '#c'],
+		visible: [true, true, true],
+		maxGroups: 2,
+		otherColor: '#999',
+	});
+
+	it('maps a drawn bar back to its source group and colour', () => {
+		expect(resolveClickedGroup(drawn, 0, series)).toStrictEqual({
+			series: series[0],
+			color: '#a',
+		});
+	});
+
+	it('refuses Other and empty space', () => {
+		expect(resolveClickedGroup(drawn, 1, series)).toBeNull();
+		expect(resolveClickedGroup(drawn, null, series)).toBeNull();
+	});
+
+	it('maps by source index, not label, when groups share a legend', () => {
+		const twins = [
+			{ label: 'Other', groupLabels: { pod: 'a' }, counts: [1] },
+			{ label: 'Other', groupLabels: { pod: 'b' }, counts: [2] },
+		];
+		const drawnTwins = groupIntoOther({
+			labels: twins.map(({ label }) => label),
+			counts: twins.map(({ counts }) => counts),
+			colors: ['#a', '#b'],
+			visible: [true, true],
+			maxGroups: 2,
+			otherColor: '#999',
+		});
+
+		expect(resolveClickedGroup(drawnTwins, 1, twins)).toStrictEqual({
+			series: twins[1],
+			color: '#b',
+		});
+	});
+});

frontend/src/lib/visualization/charts/Distribution/colors.ts

@@ -0,0 +1,29 @@
+import { Color } from '@signozhq/design-tokens';
+import { themeColors } from 'constants/theme';
+import { generateColor } from 'lib/uPlotLib/utils/generateColor';
+import { toAlphaHex } from 'lib/uPlotV2/utils/fillOpacity';
+
+const HEX_COLOR = /^#[0-9a-f]{6}$/i;
+
+export function withOpacity(color: string, opacity: number): string {
+	return HEX_COLOR.test(color) ? `${color}${toAlphaHex(opacity)}` : color;
+}
+
+/** Neutral, so the summed remainder never reads as one more group. */
+export function resolveOtherColor(isDarkMode: boolean): string {
+	return isDarkMode ? Color.BG_VANILLA_400 : Color.BG_SLATE_50;
+}
+
+export function resolveSeriesColor(
+	label: string,
+	isDarkMode: boolean,
+	customColors?: Record<string, string>,
+): string {
+	return (
+		customColors?.[label] ??
+		generateColor(
+			label,
+			isDarkMode ? themeColors.chartcolors : themeColors.lightModeColor,
+		)
+	);
+}

frontend/src/lib/visualization/charts/Distribution/components/DistributionTooltip/DistributionTooltip.module.scss

@@ -0,0 +1,116 @@
+@use '../../../../../../styles/scrollbar' as *;
+
+// Same surface as the shared and heatmap tooltips.
+.container {
+	--gutter: 14px;
+	--row-inset: 6px;
+
+	font-family: 'Inter';
+	font-size: 12px;
+	background: var(--l2-background);
+	-webkit-font-smoothing: antialiased;
+	color: var(--l2-foreground);
+	border-radius: 6px;
+	border: 1px solid var(--l2-border);
+	display: flex;
+	flex-direction: column;
+	min-width: 240px;
+
+	&.pinned {
+		border-color: var(--ring);
+	}
+}
+
+.divider {
+	display: block;
+	width: 100%;
+	height: 1px;
+	background-color: var(--l2-border);
+}
+
+// Same as the heatmap tooltip's bucket row.
+.title {
+	display: flex;
+	align-items: center;
+	justify-content: space-between;
+	gap: var(--spacing-2);
+	padding: var(--spacing-6) var(--gutter);
+}
+
+.titleBucket,
+.titleCount {
+	font-family: var(--font-mono);
+	font-size: var(--font-size-xs);
+	font-weight: 700;
+	letter-spacing: -0.01em;
+	color: var(--popover-foreground);
+	white-space: nowrap;
+	font-variant-numeric: tabular-nums;
+}
+
+.titleSeparator {
+	flex: 1;
+	border-width: 0.5px;
+	border-style: dashed;
+	border-color: currentColor;
+	min-width: 24px;
+	opacity: 0.5;
+}
+
+// One grid for the heading and every row, so their columns line up.
+.rows {
+	display: grid;
+	grid-template-columns: 12px minmax(0, 1fr) repeat(3, auto);
+	column-gap: var(--spacing-6);
+	row-gap: var(--spacing-1);
+	align-content: start;
+	padding: var(--spacing-4) var(--spacing-4) var(--spacing-6);
+	max-height: 320px;
+	overflow-y: auto;
+
+	@include custom-scrollbar;
+}
+
+.columnHeader,
+.rows .row {
+	grid-column: 1 / -1;
+	display: grid;
+	grid-template-columns: subgrid;
+	// The shared item's own `gap` would otherwise shift the subgrid off the parent.
+	column-gap: var(--spacing-6);
+	align-items: center;
+}
+
+.columnHeader {
+	padding: 0 6px var(--spacing-2);
+	font-family: var(--font-mono);
+	font-size: 10px;
+	letter-spacing: 0.06em;
+	text-transform: uppercase;
+	color: var(--muted-foreground);
+
+	> span:nth-child(n + 2) {
+		text-align: right;
+	}
+}
+
+.columnLabel {
+	grid-column: 1 / 3;
+	min-width: 0;
+	overflow: hidden;
+	text-overflow: ellipsis;
+	white-space: nowrap;
+}
+
+.rows .row {
+	border-radius: var(--radius);
+	font-variant-numeric: tabular-nums;
+
+	&[data-is-active='true'] {
+		background: var(--l3-background);
+	}
+
+	> :nth-child(n + 3) {
+		text-align: right;
+	}
+}

frontend/src/lib/visualization/charts/Distribution/components/DistributionTooltip/DistributionTooltip.tsx

@@ -0,0 +1,154 @@
+import { useMemo } from 'react';
+import cx from 'classnames';
+import {
+	formatRowLabel,
+	resolveRowIndex,
+} from 'lib/uPlotV2/plugins/HeatmapPlugin/geometry';
+import TooltipPinnedBadge from 'lib/uPlotV2/components/Tooltip/components/TooltipPinnedBadge/TooltipPinnedBadge';
+import ItemStyles from 'lib/uPlotV2/components/Tooltip/components/TooltipItem/TooltipItem.module.scss';
+
+import { resolveNearestSeries } from '../../layout';
+import {
+	buildDistributionTooltipRows,
+	formatPercent,
+	resolveGroupColumn,
+} from './distributionTooltipContent';
+import { DistributionTooltipProps } from './types';
+
+import Styles from './DistributionTooltip.module.scss';
+
+/**
+ * The bucket comes from the live cursor, not uPlot's `cursor.idx`: that snaps to the
+ * nearest bucket centre, which on uneven widths is often the neighbour.
+ */
+export default function DistributionTooltip({
+	uPlotInstance,
+	xAxis,
+	layout,
+	labels,
+	colors,
+	counts,
+	formatBound,
+	isPinned,
+	dismiss,
+	renderTooltipFooter,
+}: DistributionTooltipProps): JSX.Element | null {
+	// Read outside the memo: uPlot mutates the same instance on every move.
+	const { left = -10, top = -10 } = uPlotInstance.cursor;
+
+	const hover = useMemo(() => {
+		if (left < 0 || top < 0) {
+			return null;
+		}
+		const x = uPlotInstance.posToVal(left, 'x');
+		const bucket = resolveRowIndex(xAxis.edges, x);
+		if (bucket === null) {
+			return null;
+		}
+		return {
+			bucket,
+			series: resolveNearestSeries(
+				layout,
+				bucket,
+				x,
+				uPlotInstance.posToVal(top, 'y'),
+			),
+		};
+	}, [left, top, uPlotInstance, xAxis, layout]);
+
+	const groupColumn = useMemo(() => resolveGroupColumn(labels), [labels]);
+
+	const rows = useMemo(
+		() =>
+			hover
+				? buildDistributionTooltipRows({
+						labels,
+						colors,
+						counts,
+						bucket: hover.bucket,
+						hoveredSeries: hover.series,
+						formatLabel: groupColumn.format,
+					})
+				: [],
+		[hover, labels, colors, counts, groupColumn],
+	);
+
+	if (!hover) {
+		return null;
+	}
+
+	const bucket = xAxis.rows[hover.bucket];
+	const bucketTotal = rows.reduce((sum, row) => sum + row.count, 0);
+
+	return (
+		<div
+			className={cx(Styles.container, { [Styles.pinned]: isPinned })}
+			data-pinned={isPinned}
+			data-testid="distribution-tooltip"
+		>
+			<div className={Styles.title}>
+				<span
+					className={Styles.titleBucket}
+					data-testid="distribution-tooltip-range"
+				>
+					{formatRowLabel(bucket, formatBound)}
+				</span>
+				<span className={Styles.titleSeparator} />
+				<span
+					className={Styles.titleCount}
+					data-testid="distribution-tooltip-total"
+				>
+					{bucketTotal.toLocaleString()}
+				</span>
+				{isPinned && <TooltipPinnedBadge />}
+			</div>
+
+			<span className={Styles.divider} />
+
+			<div className={Styles.rows}>
+				<div className={Styles.columnHeader}>
+					<span
+						className={Styles.columnLabel}
+						title={groupColumn.heading}
+						data-testid="distribution-tooltip-group-heading"
+					>
+						{groupColumn.heading}
+					</span>
+					<span>Count</span>
+					<span>% Total</span>
+					<span data-testid="distribution-tooltip-cumulative-heading">
+						{bucket.isOverflow ? 'All' : `≤ ${formatBound(bucket.upper)}`}
+					</span>
+				</div>
+				{rows.map((row) => (
+					<div
+						key={row.seriesIndex}
+						className={cx(ItemStyles.uplotTooltipItem, Styles.row)}
+						data-is-active={row.isHovered}
+						data-testid="distribution-tooltip-row"
+						data-hovered={row.isHovered}
+					>
+						<span
+							className={ItemStyles.uplotTooltipItemMarker}
+							style={{ borderColor: row.color, backgroundColor: row.color }}
+						/>
+						<span className={ItemStyles.uplotTooltipItemLabel} title={row.label}>
+							{row.label}
+						</span>
+						<span className={ItemStyles.uplotTooltipItemValue}>
+							{row.count.toLocaleString()}
+						</span>
+						<span className={ItemStyles.uplotTooltipItemValue}>
+							{formatPercent(row.share)}
+						</span>
+						<span className={ItemStyles.uplotTooltipItemValue}>
+							{formatPercent(row.cumulativeShare)}
+						</span>
+					</div>
+				))}
+			</div>
+
+			{renderTooltipFooter?.({ isPinned, dismiss })}
+		</div>
+	);
+}

frontend/src/lib/visualization/charts/Distribution/components/DistributionTooltip/__tests__/DistributionTooltip.test.tsx

@@ -0,0 +1,88 @@
+import { StackMode } from 'lib/uPlotV2/config/types';
+import {
+	resolveDistributionBars,
+	resolveDistributionXAxis,
+} from 'lib/visualization/charts/Distribution/layout';
+import { render, screen } from 'tests/test-utils';
+import type uPlot from 'uplot';
+
+import DistributionTooltip from '../DistributionTooltip';
+
+// Buckets ≤ 10, (10, 20], (20, 40], > 40 in slots [0, 1] … [3, 4].
+const xAxis = resolveDistributionXAxis([10, 20, 40]);
+const counts = [
+	[1, 4, 2, 0],
+	[0, 6, 1, 1],
+];
+const layout = resolveDistributionBars({
+	xAxis,
+	counts,
+	stack: StackMode.Normal,
+	isLogY: false,
+});
+
+/** Pixels are values: the cursor at (1.5, 2) is over the first group in (10, 20]. */
+function plotAt(left: number, top: number): uPlot {
+	const plot: Partial<uPlot> = {
+		cursor: { left, top },
+		posToVal: (position: number) => position,
+	};
+	return plot as uPlot;
+}
+
+function renderTooltip(uPlotInstance: uPlot): void {
+	render(
+		<DistributionTooltip
+			uPlotInstance={uPlotInstance}
+			isPinned={false}
+			dismiss={jest.fn()}
+			xAxis={xAxis}
+			layout={layout}
+			labels={['{service.name="cart"}', '{service.name="checkout"}']}
+			colors={['#f00', '#0f0']}
+			counts={counts}
+			formatBound={(value): string => `${value} ms`}
+		/>,
+	);
+}
+
+describe('DistributionTooltip', () => {
+	it('names the bucket under the cursor and its total', () => {
+		renderTooltip(plotAt(1.5, 2));
+
+		expect(screen.getByTestId('distribution-tooltip-range')).toHaveTextContent(
+			'10 ms – 20 ms',
+		);
+		expect(screen.getByTestId('distribution-tooltip-total')).toHaveTextContent(
+			'10',
+		);
+	});
+
+	it('heads the columns with the group-by key and the bucket bound', () => {
+		renderTooltip(plotAt(1.5, 2));
+
+		expect(
+			screen.getByTestId('distribution-tooltip-group-heading'),
+		).toHaveTextContent('service.name');
+		expect(
+			screen.getByTestId('distribution-tooltip-cumulative-heading'),
+		).toHaveTextContent('≤ 20 ms');
+	});
+
+	it('lists every group in legend order, the hovered one active', () => {
+		renderTooltip(plotAt(1.5, 2));
+
+		const rows = screen.getAllByTestId('distribution-tooltip-row');
+		expect(rows).toHaveLength(2);
+		expect(rows[0]).toHaveTextContent('cart457%71%');
+		expect(rows[0]).toHaveAttribute('data-is-active', 'true');
+		expect(rows[1]).toHaveTextContent('checkout675%75%');
+		expect(rows[1]).toHaveAttribute('data-is-active', 'false');
+	});
+
+	it('renders nothing off the plot', () => {
+		renderTooltip(plotAt(-1, -1));
+
+		expect(screen.queryByTestId('distribution-tooltip')).not.toBeInTheDocument();
+	});
+});

frontend/src/lib/visualization/charts/Distribution/components/DistributionTooltip/__tests__/distributionTooltipContent.test.ts

@@ -0,0 +1,73 @@
+import {
+	buildDistributionTooltipRows,
+	formatPercent,
+	resolveGroupColumn,
+} from '../distributionTooltipContent';
+
+describe('formatPercent', () => {
+	it('rounds, and never shows a real share as 0%', () => {
+		expect(formatPercent(0.256)).toBe('26%');
+		expect(formatPercent(0.004)).toBe('<1%');
+		expect(formatPercent(0)).toBe('0%');
+	});
+});
+
+describe('resolveGroupColumn', () => {
+	it('names the column after a shared single key and shows its values', () => {
+		const column = resolveGroupColumn([
+			'{service.name="cart"}',
+			'{service.name="checkout"}',
+		]);
+
+		expect(column.heading).toBe('service.name');
+		expect(column.format('{service.name="cart"}')).toBe('cart');
+	});
+
+	it('keeps full labels for several keys or mixed labels', () => {
+		const several = resolveGroupColumn(['{env="prod", service.name="cart"}']);
+		const mixed = resolveGroupColumn(['{service.name="cart"}', 'Other']);
+
+		expect(several.heading).toBe('Group');
+		expect(several.format('{env="prod", service.name="cart"}')).toBe(
+			'{env="prod", service.name="cart"}',
+		);
+		expect(mixed.heading).toBe('Group');
+	});
+});
+
+describe('buildDistributionTooltipRows', () => {
+	it('gives each drawn group, in legend order, its count, share and cumulative share', () => {
+		const rows = buildDistributionTooltipRows({
+			labels: ['cart', 'checkout'],
+			colors: ['#f00', '#0f0'],
+			counts: [
+				[2, 6, 2],
+				[5, 0, 5],
+			],
+			bucket: 1,
+			hoveredSeries: 0,
+			formatLabel: (label) => label.toUpperCase(),
+		});
+
+		expect(rows).toStrictEqual([
+			{
+				seriesIndex: 0,
+				label: 'CART',
+				color: '#f00',
+				count: 6,
+				share: 0.6,
+				cumulativeShare: 0.8,
+				isHovered: true,
+			},
+			{
+				seriesIndex: 1,
+				label: 'CHECKOUT',
+				color: '#0f0',
+				count: 0,
+				share: 0,
+				cumulativeShare: 0.5,
+				isHovered: false,
+			},
+		]);
+	});
+});

frontend/src/lib/visualization/charts/Distribution/components/DistributionTooltip/distributionTooltipContent.ts

@@ -0,0 +1,70 @@
+import { DistributionGroupColumn, DistributionTooltipRow } from './types';
+
+const SINGLE_LABEL = /^\{([^=,]+)="([^"]*)"\}$/;
+
+/** `<1%` rather than `0%`, so a share that exists never reads as none. */
+export function formatPercent(share: number): string {
+	if (share > 0 && share < 0.01) {
+		return '<1%';
+	}
+	return `${Math.round(share * 100)}%`;
+}
+
+/**
+ * Names the group column after the one group-by key every label shares, showing just
+ * its values; anything else (several keys, Other) keeps the full labels.
+ */
+export function resolveGroupColumn(labels: string[]): DistributionGroupColumn {
+	const keys = new Set<string>();
+	labels.forEach((label) => {
+		keys.add(SINGLE_LABEL.exec(label)?.[1] ?? '');
+	});
+	const [key] = [...keys];
+	if (keys.size !== 1 || !key) {
+		return { heading: 'Group', format: (label) => label };
+	}
+	return {
+		heading: key,
+		format: (label) => SINGLE_LABEL.exec(label)?.[2] ?? label,
+	};
+}
+
+/** One row per drawn group, in legend order, with its count in `bucket`. */
+export function buildDistributionTooltipRows({
+	labels,
+	colors,
+	counts,
+	bucket,
+	hoveredSeries,
+	formatLabel,
+}: {
+	labels: string[];
+	colors: string[];
+	/** `counts[series][bucket]`. */
+	counts: number[][];
+	bucket: number;
+	hoveredSeries: number | null;
+	formatLabel: (label: string) => string;
+}): DistributionTooltipRow[] {
+	return labels.map((label, series) => {
+		const seriesCounts = counts[series] ?? [];
+		let total = 0;
+		let atOrBelow = 0;
+		seriesCounts.forEach((count, index) => {
+			total += count;
+			if (index <= bucket) {
+				atOrBelow += count;
+			}
+		});
+		const count = seriesCounts[bucket] ?? 0;
+		return {
+			seriesIndex: series,
+			label: formatLabel(label),
+			color: colors[series],
+			count,
+			share: total > 0 ? count / total : 0,
+			cumulativeShare: total > 0 ? atOrBelow / total : 0,
+			isHovered: series === hoveredSeries,
+		};
+	});
+}

frontend/src/lib/visualization/charts/Distribution/components/DistributionTooltip/types.ts

@@ -0,0 +1,39 @@
+import type {
+	IRenderTooltipFooterArgs,
+	TooltipRenderArgs,
+} from 'lib/uPlotV2/components/types';
+
+import type { DistributionBarsLayout } from '../../layout';
+import type { DistributionXAxis } from '../../types';
+
+export interface DistributionTooltipRow {
+	/** Index among the drawn series. */
+	seriesIndex: number;
+	label: string;
+	color: string;
+	count: number;
+	/** Of the group's own total over the range. */
+	share: number;
+	/** Of the group's total, at or below this bucket. */
+	cumulativeShare: number;
+	isHovered: boolean;
+}
+
+export interface DistributionGroupColumn {
+	heading: string;
+	format: (label: string) => string;
+}
+
+export interface DistributionTooltipProps extends Pick<
+	TooltipRenderArgs,
+	'uPlotInstance' | 'isPinned' | 'dismiss'
+> {
+	xAxis: DistributionXAxis;
+	layout: DistributionBarsLayout;
+	labels: string[];
+	colors: string[];
+	/** `counts[series][bucket]`. */
+	counts: number[][];
+	formatBound: (value: number) => string;
+	renderTooltipFooter?: (args: IRenderTooltipFooterArgs) => React.ReactNode;
+}

frontend/src/lib/visualization/charts/Distribution/config.ts

@@ -0,0 +1,288 @@
+import { PrecisionOption } from 'components/Graph/types';
+import {
+	DistributionType,
+	DrawStyle,
+	StackMode,
+} from 'lib/uPlotV2/config/types';
+import { UPlotConfigBuilder } from 'lib/uPlotV2/config/UPlotConfigBuilder';
+import { createVariableWidthBarsPathBuilder } from 'lib/uPlotV2/paths/variableWidthBars';
+import { resolveRowIndex } from 'lib/uPlotV2/plugins/HeatmapPlugin/geometry';
+import { createHatchPattern } from 'lib/uPlotV2/plugins/HeatmapPlugin/paint';
+import uPlot from 'uplot';
+
+import { withOpacity } from './colors';
+import {
+	drawPercentileMarkers,
+	MARKER_HIT_PX,
+	PercentileMarkerHitArea,
+	resolveHoveredMarker,
+} from './drawPercentileMarkers';
+import {
+	DistributionBarsLayout,
+	LOG_Y_BASE,
+	resolveNearestSeries,
+	thinLabelledSplits,
+} from './layout';
+import { DistributionPercentile, groupPercentileMarkers } from './percentiles';
+import { DistributionXAxis } from './types';
+import { createBoundFormatter } from './utils';
+
+/** Minimum space between two x tick labels, in CSS pixels. */
+const X_LABEL_GAP_PX = 12;
+const BAR_GAP_PX = 1;
+const BAR_OPACITY = 0.85;
+const OVERFLOW_BAR_OPACITY = 0.4;
+/** Every group but the hovered one fades to this. */
+const DIMMED_BAR_OPACITY = 0.25;
+const DIMMED_OVERFLOW_BAR_OPACITY = 0.12;
+const OVERFLOW_AXIS_LABEL = '∞';
+/** Headroom above the tallest bar: a fraction on linear, a factor on log. Marker
+ *  labels sit at the top of the plot, so they take more. */
+const LINEAR_HEADROOM = 1.1;
+const LINEAR_HEADROOM_WITH_MARKERS = 1.3;
+const LOG_HEADROOM = 2;
+const LOG_HEADROOM_WITH_MARKERS = 6;
+
+function resolveYRange({
+	yMax,
+	isLogY,
+	stack,
+	hasMarkers,
+}: {
+	yMax: number;
+	isLogY: boolean;
+	stack: StackMode;
+	hasMarkers: boolean;
+}): [number, number] {
+	if (stack === StackMode.Percent) {
+		return [0, hasMarkers ? 100 * LINEAR_HEADROOM_WITH_MARKERS : 100];
+	}
+	if (isLogY) {
+		const headroom = hasMarkers ? LOG_HEADROOM_WITH_MARKERS : LOG_HEADROOM;
+		return [LOG_Y_BASE, Math.max(yMax, LOG_Y_BASE) * headroom];
+	}
+	const headroom = hasMarkers ? LINEAR_HEADROOM_WITH_MARKERS : LINEAR_HEADROOM;
+	return [0, yMax > 0 ? yMax * headroom : 1];
+}
+
+export interface BuildDistributionConfigArgs {
+	id: string;
+	xAxis: DistributionXAxis;
+	layout: DistributionBarsLayout;
+	labels: string[];
+	colors: string[];
+	stack: StackMode;
+	isLogY: boolean;
+	isDarkMode: boolean;
+	/** Drawn across the plot, labelled at the top. */
+	markers: DistributionPercentile[];
+	/** Unit of the bucket bounds; counts take none. */
+	xAxisUnit?: string;
+	decimalPrecision?: PrecisionOption;
+}
+
+export function buildDistributionConfig({
+	id,
+	xAxis,
+	layout,
+	labels,
+	colors,
+	stack,
+	isLogY,
+	isDarkMode,
+	markers,
+	xAxisUnit,
+	decimalPrecision,
+}: BuildDistributionConfigArgs): UPlotConfigBuilder {
+	const builder = new UPlotConfigBuilder({ id });
+	// uPlot's focus picks the series nearest in value, meaningless for stacked bars; the
+	// setCursor hook focuses the one under the cursor itself. Alpha 1 leaves the
+	// dimming to the bar fills.
+	builder.setFocus({ alpha: 1 });
+	// The x range is pinned to the buckets, so a drag-zoom would only flash a box.
+	builder.setCursor({
+		focus: { prox: -1 },
+		points: { show: false },
+		drag: { x: false, y: false },
+	});
+
+	const formatBound = createBoundFormatter(xAxisUnit, decimalPrecision);
+
+	builder.addScale({
+		scaleKey: 'x',
+		time: false,
+		auto: false,
+		range: (): [number, number] => [xAxis.min, xAxis.max],
+	});
+	const yRange = resolveYRange({
+		yMax: layout.yMax,
+		isLogY,
+		stack,
+		hasMarkers: markers.length > 0,
+	});
+	builder.addScale({
+		scaleKey: 'y',
+		time: false,
+		auto: false,
+		distribution: isLogY ? DistributionType.Logarithmic : DistributionType.Linear,
+		range: (): [number, number] => yRange,
+	});
+
+	const axisSplits =
+		xAxis.overflowSplit === null
+			? xAxis.splits
+			: [...xAxis.splits, xAxis.overflowSplit];
+	const splitLabels = new Map<number, string>();
+	xAxis.splits.forEach((split, index) => {
+		splitLabels.set(split, formatBound(xAxis.rows[index].upper));
+	});
+	if (xAxis.overflowSplit !== null) {
+		splitLabels.set(xAxis.overflowSplit, OVERFLOW_AXIS_LABEL);
+	}
+
+	const labelOf = (split: number): string =>
+		splitLabels.get(split) ?? formatBound(xAxis.toBucketValue(split));
+
+	builder.addAxis({
+		scaleKey: 'x',
+		side: 2,
+		isDarkMode,
+		// Thinned by each label's own width: bound labels run from `5 s` to
+		// `16.67 mins`, so no fixed spacing keeps them apart.
+		splits: (self, axisIdx): number[] => {
+			const visible = axisSplits.filter(
+				(split) => split >= xAxis.min && split <= xAxis.max,
+			);
+			const font = self.axes[axisIdx]?.font?.[0];
+			if (font) {
+				self.ctx.font = font;
+			}
+			const kept = thinLabelledSplits({
+				positions: visible.map((split) => self.valToPos(split, 'x')),
+				widths: visible.map(
+					(split) => self.ctx.measureText(labelOf(split)).width / uPlot.pxRatio,
+				),
+				gap: X_LABEL_GAP_PX,
+			});
+			return kept.map((index) => visible[index]);
+		},
+		values: (_, splits): string[] => splits.map(labelOf),
+	});
+	builder.addAxis({
+		scaleKey: 'y',
+		side: 3,
+		isDarkMode,
+		yAxisUnit: stack === StackMode.Percent ? 'percent' : 'short',
+		// The marker headroom runs a share axis past 100%, which labels nothing real.
+		...(stack === StackMode.Percent && {
+			filter: (_self: uPlot, splits: number[]): Array<number | null> =>
+				splits.map((split) => (split <= 100 ? split : null)),
+		}),
+	});
+
+	let hatchPattern: CanvasPattern | null | undefined;
+	const getHatchPattern = (
+		ctx: CanvasRenderingContext2D,
+	): CanvasPattern | null => {
+		hatchPattern ??= createHatchPattern(ctx, isDarkMode);
+		return hatchPattern;
+	};
+
+	// Read by every series' fill on each draw; a change redraws the paths.
+	const hover: {
+		series: number | null;
+		focused: number | null;
+		marker: number | null;
+	} = { series: null, focused: null, marker: null };
+	const plotMarkers = groupPercentileMarkers(
+		markers.filter(
+			({ axisValue }) => axisValue >= xAxis.min && axisValue <= xAxis.max,
+		),
+	);
+	let markerHitAreas: PercentileMarkerHitArea[] = [];
+	const isDimmed = (seriesIndex: number): boolean =>
+		hover.series !== null && hover.series !== seriesIndex;
+
+	labels.forEach((label, seriesIndex) => {
+		const color = colors[seriesIndex];
+		builder.addSeries({
+			scaleKey: 'y',
+			label,
+			drawStyle: DrawStyle.Bar,
+			pathBuilder: createVariableWidthBarsPathBuilder({
+				getBars: () => layout.rects[seriesIndex] ?? [],
+				fill: () =>
+					withOpacity(
+						color,
+						isDimmed(seriesIndex) ? DIMMED_BAR_OPACITY : BAR_OPACITY,
+					),
+				hatchedFill: () =>
+					withOpacity(
+						color,
+						isDimmed(seriesIndex)
+							? DIMMED_OVERFLOW_BAR_OPACITY
+							: OVERFLOW_BAR_OPACITY,
+					),
+				getHatchPattern,
+				gapPx: BAR_GAP_PX,
+			}),
+			lineColor: color,
+			lineWidth: 0,
+			colorMapping: {},
+			isDarkMode,
+			showPoints: false,
+			spanGaps: false,
+		});
+	});
+
+	builder.addHook('draw', (u: uPlot): void => {
+		markerHitAreas = drawPercentileMarkers(
+			u,
+			plotMarkers,
+			formatBound,
+			isDarkMode,
+			hover.marker,
+		);
+	});
+
+	// Registered as a hook, not a plugin, so it runs before TooltipPlugin's: the tooltip
+	// only shows for a focused series, and must find it focused when it positions.
+	builder.addHook('setCursor', (u: uPlot): void => {
+		const { left = -1, top = -1 } = u.cursor;
+		const isOnPlot = left >= 0 && top >= 0;
+		const x = isOnPlot ? u.posToVal(left, 'x') : Number.NaN;
+		const bucket = isOnPlot ? resolveRowIndex(xAxis.edges, x) : null;
+		const marker = isOnPlot
+			? resolveHoveredMarker(markerHitAreas, left, top, MARKER_HIT_PX)
+			: null;
+		// Over a marker, the bars neither dim nor show their tooltip.
+		const hovered =
+			bucket === null || marker !== null
+				? null
+				: resolveNearestSeries(layout, bucket, x, u.posToVal(top, 'y'));
+		// An empty bucket still gets a tooltip, as a bar chart's zero column does; with no
+		// nearest group to name, the first stands in.
+		const isEmptyBucket = bucket !== null && marker === null && hovered === null;
+		const focused = isEmptyBucket && labels.length > 0 ? 0 : hovered;
+
+		if (focused !== hover.focused) {
+			hover.focused = focused;
+			u.setSeries(focused === null ? null : focused + 1, { focus: true });
+		}
+		if (marker !== hover.marker) {
+			// The crosshair would cut through the marker's badges.
+			u.root
+				.querySelectorAll<HTMLElement>('.u-cursor-x, .u-cursor-y')
+				.forEach((line) => {
+					line.style.visibility = marker === null ? '' : 'hidden';
+				});
+		}
+		if (hovered !== hover.series || marker !== hover.marker) {
+			hover.series = hovered;
+			hover.marker = marker;
+			u.redraw(true, false);
+		}
+	});
+
+	return builder;
+}

frontend/src/lib/visualization/charts/Distribution/drawPercentileMarkers.ts

@@ -0,0 +1,242 @@
+import { Color } from '@signozhq/design-tokens';
+import { themeColors } from 'constants/theme';
+import uPlot from 'uplot';
+
+import {
+	DistributionPercentile,
+	formatPercentileBadge,
+	formatPercentileValue,
+} from './percentiles';
+
+const MARKER_DASH: [number, number] = [3, 3];
+const MARKER_FONT_SIZE_PX = 9;
+/** Space between a badge's name and its diamond's edges. */
+const MARKER_BADGE_PADDING_PX = 2;
+const MARKER_BADGE_GAP_PX = 2;
+const MARKER_VALUE_FONT_SIZE_PX = 11;
+/** How far from a marker line the cursor still hovers it, in CSS pixels. */
+export const MARKER_HIT_PX = 4;
+const MARKER_PILL_PADDING_X_PX = 6;
+const MARKER_PILL_PADDING_Y_PX = 3;
+const MARKER_PILL_RADIUS_PX = 4;
+/** Height of the pill's notch pointing up at the line; also its gap from the axis. */
+const MARKER_PILL_POINTER_PX = 4;
+
+interface HitRect {
+	left: number;
+	right: number;
+	top: number;
+	bottom: number;
+}
+
+/** A drawn marker's hover targets, in CSS pixels relative to the plot. */
+export interface PercentileMarkerHitArea {
+	x: number;
+	badges: HitRect[];
+}
+
+/**
+ * The marker under `(x, y)`: one whose badge it is over, else the line nearest
+ * `x` within `tolerance`. `null` when none is.
+ */
+export function resolveHoveredMarker(
+	areas: PercentileMarkerHitArea[],
+	x: number,
+	y: number,
+	tolerance: number,
+): number | null {
+	const overBadge = areas.findIndex(({ badges }) =>
+		badges.some(
+			(badge) =>
+				x >= badge.left && x <= badge.right && y >= badge.top && y <= badge.bottom,
+		),
+	);
+	if (overBadge !== -1) {
+		return overBadge;
+	}
+	let nearest: number | null = null;
+	let nearestDistance = tolerance;
+	areas.forEach((area, index) => {
+		const distance = Math.abs(area.x - x);
+		if (distance <= nearestDistance) {
+			nearest = index;
+			nearestDistance = distance;
+		}
+	});
+	return nearest;
+}
+
+/**
+ * Stacks marker badges into rows so none overlap: each goes in the first row whose
+ * last badge ends before it starts. Input and output are in the same pixel space.
+ */
+export function layoutMarkerLabels(
+	labels: Array<{ x: number; width: number }>,
+	gap: number,
+): number[] {
+	const rowEnds: number[] = [];
+	const order = labels
+		.map((label, index) => ({ ...label, index }))
+		.sort((a, b) => a.x - b.x);
+	const rows = new Array<number>(labels.length).fill(0);
+
+	order.forEach(({ x, width, index }) => {
+		let row = rowEnds.findIndex((end) => x >= end + gap);
+		if (row === -1) {
+			row = rowEnds.length;
+			rowEnds.push(0);
+		}
+		rowEnds[row] = x + width;
+		rows[index] = row;
+	});
+
+	return rows;
+}
+
+/** A square diamond centred on `(x, y)` with half-diagonal `r`, filled then outlined. */
+function drawDiamond(
+	ctx: CanvasRenderingContext2D,
+	x: number,
+	y: number,
+	r: number,
+	fill: string,
+	stroke: string,
+): void {
+	ctx.beginPath();
+	ctx.moveTo(x, y - r);
+	ctx.lineTo(x + r, y);
+	ctx.lineTo(x, y + r);
+	ctx.lineTo(x - r, y);
+	ctx.closePath();
+	ctx.fillStyle = fill;
+	ctx.fill();
+	ctx.strokeStyle = stroke;
+	ctx.stroke();
+}
+
+/**
+ * Dashed lines across the plot with a diamond badge at each end naming the
+ * percentile, one per group on the same spot; badges stack into rows so none overlap. The hovered marker is
+ * emphasised and shows its value on the x axis. Returns each marker's hover targets.
+ */
+export function drawPercentileMarkers(
+	u: uPlot,
+	markers: DistributionPercentile[][],
+	formatBound: (value: number) => string,
+	isDarkMode: boolean,
+	hovered: number | null,
+): PercentileMarkerHitArea[] {
+	if (markers.length === 0) {
+		return [];
+	}
+	const { ctx, bbox } = u;
+	const { pxRatio } = uPlot;
+	const color = isDarkMode ? themeColors.white : themeColors.black;
+	const background = isDarkMode ? Color.BG_INK_400 : Color.BG_VANILLA_100;
+	const bottom = bbox.top + bbox.height;
+
+	ctx.save();
+	ctx.font = `600 ${MARKER_FONT_SIZE_PX * pxRatio}px Inter, sans-serif`;
+	ctx.textAlign = 'center';
+	ctx.textBaseline = 'middle';
+
+	const named = markers.map((group) => {
+		const text = formatPercentileBadge(group);
+		return { text, width: ctx.measureText(text).width };
+	});
+	// One square diamond for all, fitting the widest name's box: |dx| + |dy| ≤ r at
+	// its corners. Cap height stands in for the text's height.
+	const r =
+		(Math.max(...named.map(({ width }) => width)) +
+			MARKER_FONT_SIZE_PX * pxRatio * 0.7) /
+			2 +
+		MARKER_BADGE_PADDING_PX * pxRatio;
+	const badges = markers.map((group, index) => ({
+		text: named[index].text,
+		x: u.valToPos(group[0].axisValue, 'x', true),
+	}));
+	const rows = layoutMarkerLabels(
+		badges.map(({ x }) => ({ x: x - r, width: 2 * r })),
+		MARKER_BADGE_GAP_PX * pxRatio,
+	);
+	const rowStep = 2 * r + MARKER_BADGE_GAP_PX * pxRatio;
+	const badgeCentres = (index: number): [number, number] => {
+		const offset = r + rows[index] * rowStep;
+		return [bbox.top + offset, bottom - offset];
+	};
+
+	const drawMarker = (index: number): void => {
+		const { text, x } = badges[index];
+		const isHovered = index === hovered;
+
+		ctx.globalAlpha = isHovered ? 1 : 0.55;
+		ctx.strokeStyle = color;
+		ctx.lineWidth = pxRatio;
+		ctx.setLineDash(MARKER_DASH.map((dash) => dash * pxRatio));
+		ctx.beginPath();
+		ctx.moveTo(x, bbox.top);
+		ctx.lineTo(x, bottom);
+		ctx.stroke();
+
+		ctx.globalAlpha = 1;
+		ctx.setLineDash([]);
+		badgeCentres(index).forEach((y) => {
+			drawDiamond(ctx, x, y, r, isHovered ? color : background, color);
+			ctx.fillStyle = isHovered ? background : color;
+			ctx.fillText(text, x, y);
+		});
+
+		if (!isHovered) {
+			return;
+		}
+		// The value sits on the x axis under the line, over the tick labels, in a pill
+		// whose notch points up at the line.
+		ctx.font = `500 ${MARKER_VALUE_FONT_SIZE_PX * pxRatio}px Inter, sans-serif`;
+		const value = formatPercentileValue(markers[index], formatBound);
+		const padX = MARKER_PILL_PADDING_X_PX * pxRatio;
+		const padY = MARKER_PILL_PADDING_Y_PX * pxRatio;
+		const pointer = MARKER_PILL_POINTER_PX * pxRatio;
+		const width = ctx.measureText(value).width + 2 * padX;
+		const height = MARKER_VALUE_FONT_SIZE_PX * pxRatio + 2 * padY;
+		const left = Math.min(Math.max(x - width / 2, 0), ctx.canvas.width - width);
+		const top = bottom + 2 * pointer;
+		const notchX = Math.min(
+			Math.max(x, left + pointer + MARKER_PILL_RADIUS_PX * pxRatio),
+			left + width - pointer - MARKER_PILL_RADIUS_PX * pxRatio,
+		);
+		// A halo in the chart's background hides the tick labels it overlaps.
+		ctx.fillStyle = background;
+		ctx.fillRect(left - padX, top, width + 2 * padX, height + 2 * padY);
+		ctx.fillStyle = isDarkMode ? Color.BG_SLATE_400 : Color.BG_INK_400;
+		ctx.beginPath();
+		ctx.roundRect(left, top, width, height, MARKER_PILL_RADIUS_PX * pxRatio);
+		ctx.moveTo(notchX - pointer, top);
+		ctx.lineTo(notchX, top - pointer);
+		ctx.lineTo(notchX + pointer, top);
+		ctx.closePath();
+		ctx.fill();
+		ctx.fillStyle = Color.BG_VANILLA_100;
+		ctx.fillText(value, left + width / 2, top + height / 2);
+	};
+
+	// The hovered one last, so it draws over its neighbours.
+	badges.forEach((_, index) => index !== hovered && drawMarker(index));
+	if (hovered !== null && hovered < badges.length) {
+		drawMarker(hovered);
+	}
+	ctx.restore();
+
+	return badges.map(({ x }, index) => {
+		const toPlot = (value: number, origin: number): number =>
+			(value - origin) / pxRatio;
+		return {
+			x: toPlot(x, bbox.left),
+			badges: badgeCentres(index).map((y) => ({
+				left: toPlot(x - r, bbox.left),
+				right: toPlot(x + r, bbox.left),
+				top: toPlot(y - r, bbox.top),
+				bottom: toPlot(y + r, bbox.top),
+			})),
+		};
+	});
+}

frontend/src/lib/visualization/charts/Distribution/layout.ts

@@ -0,0 +1,232 @@
+import { StackMode } from 'lib/uPlotV2/config/types';
+import {
+	cropHeatmapYAxis,
+	resolveHeatmapYAxis,
+} from 'lib/uPlotV2/plugins/HeatmapPlugin/geometry';
+import { HeatmapAxisScale } from 'lib/uPlotV2/plugins/HeatmapPlugin/types';
+
+import { DistributionBarRect, DistributionXAxis } from './types';
+
+/** Bottom of a log count axis: a bar has to start somewhere above zero. */
+export const LOG_Y_BASE = 1;
+
+/**
+ * N bounds give N + 1 buckets: `≤ first`, the finite ones, and `> last`. Every bucket
+ * is equally wide: bucket `i` spans `[i, i + 1]`, and ticks still name the bounds.
+ */
+export function resolveDistributionXAxis(buckets: number[]): DistributionXAxis {
+	const { rows, overflowSplit } = resolveHeatmapYAxis(
+		buckets,
+		HeatmapAxisScale.Linear,
+	);
+	const edges = rows.map((_, index) => index).concat(rows.length);
+	return {
+		rows,
+		edges,
+		splits: rows.slice(0, -1).map((_, index) => index + 1),
+		overflowSplit: overflowSplit === null ? null : rows.length,
+		toBucketValue: (axisValue: number): number => {
+			const index = Math.min(rows.length - 1, Math.max(0, Math.floor(axisValue)));
+			const row = rows[index];
+			return row.lower + (axisValue - index) * (row.upper - row.lower);
+		},
+		min: 0,
+		max: rows.length,
+	};
+}
+
+/** Sum of each bucket across the visible series. */
+export function sumVisibleCounts(
+	counts: number[][],
+	visible: boolean[],
+	bucketCount: number,
+): number[] {
+	const totals = new Array<number>(bucketCount).fill(0);
+	counts.forEach((seriesCounts, seriesIndex) => {
+		if (!visible[seriesIndex]) {
+			return;
+		}
+		for (let bucket = 0; bucket < bucketCount; bucket += 1) {
+			totals[bucket] += seriesCounts[bucket] ?? 0;
+		}
+	});
+	return totals;
+}
+
+/** Drops empty buckets past the last occupied one, as the heatmap does. */
+export function cropDistributionXAxis(
+	axis: DistributionXAxis,
+	totals: number[],
+): DistributionXAxis {
+	return cropHeatmapYAxis(
+		axis,
+		totals.map((total) => [total]),
+	);
+}
+
+/**
+ * Narrows the axis window to the buckets overlapping `[min, max]`, never below one.
+ * A bucket straddling a bound stays whole: cutting it would misstate its count.
+ */
+export function clampDistributionXAxis(
+	axis: DistributionXAxis,
+	min?: number,
+	max?: number,
+): DistributionXAxis {
+	const { rows, edges } = axis;
+	let first = edges.indexOf(axis.min);
+	let last = edges.indexOf(axis.max) - 1;
+	while (min !== undefined && first < last && rows[first].upper <= min) {
+		first += 1;
+	}
+	while (max !== undefined && last > first && rows[last].lower >= max) {
+		last -= 1;
+	}
+	return {
+		...axis,
+		overflowSplit: rows[last].isOverflow ? axis.overflowSplit : null,
+		min: edges[first],
+		max: edges[last + 1],
+	};
+}
+
+export interface DistributionBarsLayout {
+	/** One list per series, in series order. */
+	rects: DistributionBarRect[][];
+	/** Top of the tallest bar inside the axis window, for the count axis range. */
+	yMax: number;
+}
+
+/**
+ * Every bar, in scale space. `normal` stacks the series in each bucket, `percent`
+ * stacks their shares of it, `none` splits the bucket width between them.
+ */
+export function resolveDistributionBars({
+	xAxis,
+	counts,
+	stack,
+	isLogY,
+}: {
+	xAxis: DistributionXAxis;
+	/** `counts[series][bucket]`. */
+	counts: number[][];
+	stack: StackMode;
+	isLogY: boolean;
+}): DistributionBarsLayout {
+	const { rows, edges } = xAxis;
+	const rects: DistributionBarRect[][] = counts.map(() => []);
+	const base = isLogY ? LOG_Y_BASE : 0;
+	let yMax = 0;
+
+	rows.forEach((row, bucketIndex) => {
+		const x0 = edges[bucketIndex];
+		const x1 = edges[bucketIndex + 1];
+		// Buckets outside the window are off the plot and mustn't set its height.
+		const isInWindow = x0 >= xAxis.min && x1 <= xAxis.max;
+		const total = counts.reduce(
+			(sum, seriesCounts) => sum + (seriesCounts[bucketIndex] ?? 0),
+			0,
+		);
+		let cumulative = 0;
+
+		counts.forEach((seriesCounts, seriesIndex) => {
+			const count = seriesCounts[bucketIndex] ?? 0;
+			if (count <= 0) {
+				return;
+			}
+			const bar = { bucketIndex, hatched: row.isOverflow };
+
+			if (stack === StackMode.None) {
+				// Below the log base a bar would draw downwards from the axis.
+				if (count <= base) {
+					return;
+				}
+				const width = (x1 - x0) / counts.length;
+				rects[seriesIndex].push({
+					...bar,
+					x0: x0 + seriesIndex * width,
+					x1: x0 + (seriesIndex + 1) * width,
+					y0: base,
+					y1: count,
+				});
+				if (isInWindow) {
+					yMax = Math.max(yMax, count);
+				}
+				return;
+			}
+
+			const scale = stack === StackMode.Percent ? 100 / total : 1;
+			const y0 = cumulative * scale;
+			cumulative += count;
+			const y1 = cumulative * scale;
+			if (y1 <= base) {
+				return;
+			}
+			rects[seriesIndex].push({
+				...bar,
+				x0,
+				x1,
+				y0: Math.max(y0, base),
+				y1,
+			});
+			if (isInWindow) {
+				yMax = Math.max(yMax, y1);
+			}
+		});
+	});
+
+	return { rects, yMax };
+}
+
+/**
+ * The group nearest `(x, y)` vertically in `bucket`, as uPlot focuses bar series;
+ * side by side, only the sub-bar under `x` competes. `null` over an empty bucket.
+ */
+export function resolveNearestSeries(
+	layout: DistributionBarsLayout,
+	bucket: number,
+	x: number,
+	y: number,
+): number | null {
+	const candidates = layout.rects.flatMap((rects, series) =>
+		rects
+			.filter((rect) => rect.bucketIndex === bucket)
+			.map((rect) => ({ rect, series })),
+	);
+	const underX = candidates.filter(({ rect }) => x >= rect.x0 && x < rect.x1);
+	let nearest: number | null = null;
+	let nearestDistance = Number.POSITIVE_INFINITY;
+	(underX.length > 0 ? underX : candidates).forEach(({ rect, series }) => {
+		const distance = Math.max(rect.y0 - y, y - rect.y1, 0);
+		if (distance < nearestDistance) {
+			nearest = series;
+			nearestDistance = distance;
+		}
+	});
+	return nearest;
+}
+
+/**
+ * Indexes of the ticks whose centred labels fit without touching, walking from the
+ * right so the `∞` edge survives. Positions and widths share one pixel space.
+ */
+export function thinLabelledSplits({
+	positions,
+	widths,
+	gap,
+}: {
+	positions: number[];
+	widths: number[];
+	gap: number;
+}): number[] {
+	const kept: number[] = [];
+	let leftEdge = Number.POSITIVE_INFINITY;
+	for (let index = positions.length - 1; index >= 0; index -= 1) {
+		const half = widths[index] / 2;
+		if (positions[index] + half + gap <= leftEdge) {
+			kept.push(index);
+			leftEdge = positions[index] - half;
+		}
+	}
+	return kept.reverse();
+}

frontend/src/lib/visualization/charts/Distribution/percentiles.ts

@@ -0,0 +1,110 @@
+import { DistributionXAxis } from './types';
+
+export interface DistributionPercentile {
+	/** 0–100, as configured. */
+	percentile: number;
+	/** The estimate; in overflow, the last finite bound it is known to exceed. */
+	value: number;
+	/** Where the marker is drawn, in x-scale space. */
+	axisValue: number;
+	isOverflow: boolean;
+}
+
+/**
+ * Percentiles of the summed counts, by `histogram_quantile`'s method: find the bucket
+ * holding the target rank and interpolate linearly inside it, with the lowest bucket
+ * starting at zero. So the values match a time-series panel's percentiles.
+ */
+export function computeDistributionPercentiles({
+	xAxis,
+	totals,
+	percentiles,
+}: {
+	xAxis: DistributionXAxis;
+	/** Summed visible counts per bucket. */
+	totals: number[];
+	percentiles: readonly number[];
+}): DistributionPercentile[] {
+	const { rows, edges } = xAxis;
+	const total = totals.reduce((sum, count) => sum + count, 0);
+	if (total <= 0 || rows.length === 0) {
+		return [];
+	}
+
+	return percentiles.flatMap<DistributionPercentile>((percentile) => {
+		const rank = (percentile / 100) * total;
+		let below = 0;
+		for (let index = 0; index < rows.length; index += 1) {
+			const count = totals[index] ?? 0;
+			if (count > 0 && below + count >= rank) {
+				const row = rows[index];
+				if (row.isOverflow) {
+					return [
+						{
+							percentile,
+							value: row.lower,
+							axisValue: edges[index],
+							isOverflow: true,
+						},
+					];
+				}
+				const fraction = (rank - below) / count;
+				const lower = row.isUnderflow ? Math.min(0, row.upper) : row.lower;
+				return [
+					{
+						percentile,
+						value: lower + fraction * (row.upper - lower),
+						axisValue: edges[index] + fraction * (edges[index + 1] - edges[index]),
+						isOverflow: false,
+					},
+				];
+			}
+			below += count;
+		}
+		return [];
+	});
+}
+
+export function formatPercentileName(percentile: number): string {
+	return `p${Number(percentile.toFixed(3))}`;
+}
+
+/**
+ * Markers that fall on the same spot, sharing one badge: the percentiles landing
+ * in overflow all sit on its edge. Each group is in ascending percentile order.
+ */
+export function groupPercentileMarkers(
+	markers: DistributionPercentile[],
+): DistributionPercentile[][] {
+	const groups = new Map<number, DistributionPercentile[]>();
+	markers.forEach((marker) => {
+		groups.set(marker.axisValue, [
+			...(groups.get(marker.axisValue) ?? []),
+			marker,
+		]);
+	});
+	return [...groups.values()].map((group) =>
+		[...group].sort((a, b) => a.percentile - b.percentile),
+	);
+}
+
+/** `p90` for one marker; `p90+` for a group, starting at its lowest percentile. */
+export function formatPercentileBadge(group: DistributionPercentile[]): string {
+	const name = formatPercentileName(group[0].percentile);
+	return group.length > 1 ? `${name}+` : name;
+}
+
+/**
+ * `p99 ≈ 412 ms` for an estimate; `p90, p99 > 5 s` where only the overflow bound is
+ * known. A group shares one spot, so one value and overflow flag.
+ */
+export function formatPercentileValue(
+	group: DistributionPercentile[],
+	formatBound: (value: number) => string,
+): string {
+	const names = group
+		.map(({ percentile }) => formatPercentileName(percentile))
+		.join(', ');
+	const [{ value, isOverflow }] = group;
+	return `${names} ${isOverflow ? '>' : '≈'} ${formatBound(value)}`;
+}

frontend/src/lib/visualization/charts/Distribution/topGroups.ts

@@ -0,0 +1,133 @@
+import { StackMode } from 'lib/uPlotV2/config/types';
+
+import { DistributionSeries, DistributionXAxis } from './types';
+
+/** Colours stop being told apart past this many stacked groups. */
+export const MAX_STACKED_GROUPS = 10;
+/** Narrowest a side-by-side bar may get, in CSS pixels. */
+const MIN_SIDE_BY_SIDE_BAR_PX = 3;
+export const OTHER_GROUP_LABEL = 'Other';
+
+/**
+ * How many series fit: a fixed cap when stacked, and side by side as many as keep
+ * every bar in the narrowest bucket at least `MIN_SIDE_BY_SIDE_BAR_PX` wide.
+ */
+export function resolveMaxDrawnGroups({
+	stack,
+	xAxis,
+	plotWidth,
+}: {
+	stack: StackMode;
+	xAxis: DistributionXAxis;
+	/** Approximate width of the plotting area, in CSS pixels. */
+	plotWidth: number;
+}): number {
+	if (stack !== StackMode.None) {
+		return MAX_STACKED_GROUPS;
+	}
+	const span = xAxis.max - xAxis.min;
+	let narrowest = Number.POSITIVE_INFINITY;
+	for (let index = 0; index + 1 < xAxis.edges.length; index += 1) {
+		if (xAxis.edges[index] < xAxis.max) {
+			narrowest = Math.min(narrowest, xAxis.edges[index + 1] - xAxis.edges[index]);
+		}
+	}
+	if (!(span > 0) || !Number.isFinite(narrowest)) {
+		return MAX_STACKED_GROUPS;
+	}
+	const narrowestPx = (plotWidth * narrowest) / span;
+	return Math.min(
+		MAX_STACKED_GROUPS,
+		Math.max(1, Math.floor(narrowestPx / MIN_SIDE_BY_SIDE_BAR_PX)),
+	);
+}
+
+export interface DrawnGroups {
+	labels: string[];
+	counts: number[][];
+	colors: string[];
+	/** Each drawn group's index among the source series; `null` for Other. */
+	sourceIndexes: (number | null)[];
+	/** Visible groups summed into the Other series; 0 when none were. */
+	otherGroupCount: number;
+	/** Visible groups in all, drawn or folded. */
+	visibleGroupCount: number;
+}
+
+function sum(counts: number[]): number {
+	return counts.reduce((total, count) => total + count, 0);
+}
+
+/**
+ * The visible groups to draw: all of them when they fit, else the largest by total
+ * and one Other series summing the rest. Exact, because bucket counts add. Drawn
+ * groups keep legend order.
+ */
+export function groupIntoOther({
+	labels,
+	counts,
+	colors,
+	visible,
+	maxGroups,
+	otherColor,
+}: {
+	labels: string[];
+	counts: number[][];
+	colors: string[];
+	visible: boolean[];
+	maxGroups: number;
+	otherColor: string;
+}): DrawnGroups {
+	const visibleIndexes = labels
+		.map((_, index) => index)
+		.filter((index) => visible[index]);
+
+	if (visibleIndexes.length <= maxGroups) {
+		return {
+			labels: visibleIndexes.map((index) => labels[index]),
+			counts: visibleIndexes.map((index) => counts[index]),
+			colors: visibleIndexes.map((index) => colors[index]),
+			sourceIndexes: visibleIndexes,
+			otherGroupCount: 0,
+			visibleGroupCount: visibleIndexes.length,
+		};
+	}
+
+	const keep = new Set(
+		[...visibleIndexes]
+			.sort((a, b) => sum(counts[b]) - sum(counts[a]) || a - b)
+			.slice(0, Math.max(0, maxGroups - 1)),
+	);
+	const kept = visibleIndexes.filter((index) => keep.has(index));
+	const folded = visibleIndexes.filter((index) => !keep.has(index));
+	const bucketCount = Math.max(...folded.map((index) => counts[index].length));
+	const other = Array.from({ length: bucketCount }, (_, bucket) =>
+		folded.reduce((total, index) => total + (counts[index][bucket] ?? 0), 0),
+	);
+
+	return {
+		labels: [...kept.map((index) => labels[index]), OTHER_GROUP_LABEL],
+		counts: [...kept.map((index) => counts[index]), other],
+		colors: [...kept.map((index) => colors[index]), otherColor],
+		sourceIndexes: [...kept, null],
+		otherGroupCount: folded.length,
+		visibleGroupCount: visibleIndexes.length,
+	};
+}
+
+/**
+ * The drawn group at `drawnIndex` as a source series and its colour; `null` for Other,
+ * which sums several groups no single filter can name.
+ */
+export function resolveClickedGroup(
+	drawn: DrawnGroups,
+	drawnIndex: number | null,
+	series: DistributionSeries[],
+): { series: DistributionSeries; color: string } | null {
+	const source =
+		drawnIndex === null ? null : (drawn.sourceIndexes[drawnIndex] ?? null);
+	if (drawnIndex === null || source === null) {
+		return null;
+	}
+	return { series: series[source], color: drawn.colors[drawnIndex] };
+}

frontend/src/lib/visualization/charts/Distribution/types.ts

@@ -0,0 +1,31 @@
+import type { VariableWidthBar } from 'lib/uPlotV2/paths/variableWidthBars';
+import type { HeatmapYAxis } from 'lib/uPlotV2/plugins/HeatmapPlugin/types';
+
+export interface DistributionSeries {
+	label: string;
+	/** Group-by key → value, for drilling into this group. Empty when ungrouped. */
+	groupLabels?: Record<string, string>;
+	/** One count per bucket bound plus the trailing overflow, summed over the range. */
+	counts: number[];
+}
+
+/** A click on a group's bar; never on Other, which no filter can name. */
+export interface DistributionBarClick {
+	series: DistributionSeries;
+	color: string;
+	/** Viewport coordinates of the click. */
+	coordinates: { x: number; y: number };
+}
+
+export enum DistributionYScale {
+	Linear = 'linear',
+	Log = 'log',
+}
+
+/** The bucket axis in x-scale space. The heatmap's row axis, laid sideways. */
+export type DistributionXAxis = HeatmapYAxis;
+
+/** `x` in bucket-axis units, `y` in counts (or percent); the overflow bucket is hatched. */
+export interface DistributionBarRect extends VariableWidthBar {
+	bucketIndex: number;
+}

frontend/src/lib/visualization/charts/Distribution/useDistributionBarClick.ts

@@ -0,0 +1,56 @@
+import { useCallback, useRef } from 'react';
+import { resolveRowIndex } from 'lib/uPlotV2/plugins/HeatmapPlugin/geometry';
+import type { ChartClickData } from 'lib/uPlotV2/plugins/TooltipPlugin/types';
+
+import { type DistributionBarsLayout, resolveNearestSeries } from './layout';
+import { type DrawnGroups, resolveClickedGroup } from './topGroups';
+import type {
+	DistributionBarClick,
+	DistributionSeries,
+	DistributionXAxis,
+} from './types';
+
+/** Resolves a plot click to the group under it; Other and empty buckets report none. */
+export function useDistributionBarClick({
+	xAxis,
+	layout,
+	drawn,
+	series,
+	onBarClick,
+}: {
+	xAxis: DistributionXAxis;
+	layout: DistributionBarsLayout;
+	drawn: DrawnGroups;
+	series: DistributionSeries[];
+	onBarClick?: (click: DistributionBarClick) => void;
+}): ((data: ChartClickData) => void) | undefined {
+	const onBarClickRef = useRef(onBarClick);
+	onBarClickRef.current = onBarClick;
+
+	const handleClick = useCallback(
+		({
+			xValue,
+			yValue,
+			absoluteMouseX,
+			absoluteMouseY,
+		}: ChartClickData): void => {
+			const bucket = resolveRowIndex(xAxis.edges, xValue);
+			const clicked = resolveClickedGroup(
+				drawn,
+				bucket === null
+					? null
+					: resolveNearestSeries(layout, bucket, xValue, yValue),
+				series,
+			);
+			if (clicked) {
+				onBarClickRef.current?.({
+					...clicked,
+					coordinates: { x: absoluteMouseX, y: absoluteMouseY },
+				});
+			}
+		},
+		[xAxis, layout, drawn, series],
+	);
+
+	return onBarClick ? handleClick : undefined;
+}

frontend/src/lib/visualization/charts/Distribution/utils.ts

@@ -0,0 +1,32 @@
+import { PrecisionOption } from 'components/Graph/types';
+import { getToolTipValue } from 'components/Graph/yAxisConfig';
+import uPlot from 'uplot';
+
+import { DistributionXAxis } from './types';
+
+export function createBoundFormatter(
+	unit?: string,
+	decimalPrecision?: PrecisionOption,
+): (value: number) => string {
+	return (value: number): string =>
+		getToolTipValue(String(value), unit, decimalPrecision);
+}
+
+/**
+ * `[bucket centres, ...counts per series]`. The series draw from the layout, so the
+ * data only feeds uPlot's cursor and tooltip.
+ */
+export function prepareDistributionChartData(
+	xAxis: DistributionXAxis,
+	counts: number[][],
+): uPlot.AlignedData {
+	const centres = xAxis.rows.map(
+		(_, index) => (xAxis.edges[index] + xAxis.edges[index + 1]) / 2,
+	);
+	return [
+		centres,
+		...counts.map((seriesCounts) =>
+			centres.map((_, index) => seriesCounts[index] ?? 0),
+		),
+	] as unknown as uPlot.AlignedData;
+}

frontend/src/lib/visualization/charts/types.ts

@@ -26,6 +26,11 @@ import {
 } from 'lib/uPlotV2/plugins/TooltipPlugin/types';
 import { BaseAutocompleteData } from 'types/api/queryBuilder/queryAutocompleteResponse';
 import type { StackMode } from 'lib/uPlotV2/config/types';
+import type {
+	DistributionBarClick,
+	DistributionSeries,
+	DistributionYScale,
+} from 'lib/visualization/charts/Distribution/types';
 
 interface BaseChartProps {
 	width: number;
@@ -167,6 +172,48 @@ export interface HeatmapChartProps {
 	'data-testid'?: string;
 }
 
+/**
+ * Whole-range bucket counts, one series per group, drawn as bars whose widths follow
+ * the bucket bounds. Builds its own config, since `buckets` fully determines the x
+ * axis. `buckets` and `series` must be referentially stable: a new identity rebuilds
+ * the plot.
+ */
+export interface DistributionChartProps {
+	/** Widget id; the group selection persists under it. */
+	id: string;
+	/** Ascending. N boundaries describe N+1 buckets, the last one overflow. */
+	buckets: number[];
+	series: DistributionSeries[];
+	width: number;
+	height: number;
+	isDarkMode: boolean;
+	/** Buckets wholly below it are hidden. */
+	xMin?: number;
+	/** Buckets wholly above it are hidden; unset crops trailing empty buckets. */
+	xMax?: number;
+	/** Default linear. Ignored under `percent`, whose axis is a share. */
+	yScale?: DistributionYScale;
+	/** Default normal. `none` draws the groups side by side. */
+	stack?: StackMode;
+	/** Unit of the bucket bounds; counts are always plain numbers. */
+	xAxisUnit?: string;
+	decimalPrecision?: PrecisionOption;
+	/** Hex colours keyed by group label, overriding the automatic palette. */
+	customColors?: Record<string, string>;
+	/** 0–100. Marked across the plot, over the visible groups combined. */
+	percentiles?: readonly number[];
+	/** Fires for a click on a group's bar; not on Other or empty space. */
+	onBarClick?: (click: DistributionBarClick) => void;
+	showLegend?: boolean;
+	legendPosition?: LegendPosition;
+	showTooltip?: boolean;
+	canPinTooltip?: boolean;
+	renderTooltipFooter?: (args: IRenderTooltipFooterArgs) => React.ReactNode;
+	tooltipPortalRoot?: HTMLElement | null;
+	layoutChildren?: React.ReactNode;
+	'data-testid'?: string;
+}
+
 /**
  * One resolved pie/donut slice: a display label, its (already parsed) positive
  * numeric value, and the colour used for the arc + legend swatch.

pkg/types/dashboardtypes/perses_dashboard_test.go

@@ -669,6 +669,216 @@ func TestValidateHeatmapDashboard(t *testing.T) {
 	assert.Equal(t, request, rereadRequest)
 }
 
+func TestValidateDistributionDashboard(t *testing.T) {
+	data, err := os.ReadFile("testdata/perses_distribution_panel.json")
+	require.NoError(t, err, "reading example file")
+
+	spec, err := unmarshalDashboard(data)
+	require.NoError(t, err, "unmarshal and validate failed")
+
+	require.IsType(t, &DistributionPanelSpec{}, spec.Panels["p1"].Spec.Plugin.Spec)
+	panelSpec := spec.Panels["p1"].Spec.Plugin.Spec.(*DistributionPanelSpec)
+	require.NotNil(t, panelSpec.Axes.X.Min)
+	assert.Equal(t, 10.0, *panelSpec.Axes.X.Min)
+	assert.Nil(t, panelSpec.Axes.X.Max)
+	assert.Equal(t, "log", panelSpec.Axes.Y.Scale.ValueOrDefault())
+	assert.Equal(t, "none", panelSpec.ChartAppearance.Stack.ValueOrDefault())
+	assert.True(t, panelSpec.ChartAppearance.Percentiles.Enabled)
+	assert.Equal(t, []float64{75, 99.9}, panelSpec.ChartAppearance.Percentiles.Values)
+
+	dashboard := &DashboardV2{Spec: *spec}
+	request, err := dashboard.GetPanelQuery(1, 2, "p1")
+	require.NoError(t, err, "building the panel's query failed")
+	assert.Equal(t, qb.RequestTypeDistribution, request.RequestType)
+	require.NoError(t, request.Validate(), "the request built from the panel is not a valid distribution request")
+
+	stored, err := json.Marshal(spec)
+	require.NoError(t, err, "marshal dashboard failed")
+	reread, err := unmarshalDashboard(stored)
+	require.NoError(t, err, "the stored dashboard does not validate")
+	assert.Equal(t, panelSpec, reread.Panels["p1"].Spec.Plugin.Spec)
+}
+
+func TestDistributionPanelSpecDefaults(t *testing.T) {
+	testCases := []struct {
+		name string
+		spec string
+	}{
+		{name: "EmptySpec", spec: `{}`},
+		{name: "EmptyChartAppearance", spec: `{"chartAppearance": {}}`},
+		{name: "EmptyPercentiles", spec: `{"chartAppearance": {"percentiles": {}}}`},
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			var plugin PanelPlugin
+			require.NoError(t, json.Unmarshal([]byte(`{"kind": "signoz/DistributionPanel", "spec": `+testCase.spec+`}`), &plugin))
+
+			spec := plugin.Spec.(*DistributionPanelSpec)
+			assert.Nil(t, spec.Axes.X.Min)
+			assert.Nil(t, spec.Axes.X.Max)
+			assert.Equal(t, "linear", spec.Axes.Y.Scale.ValueOrDefault())
+			assert.Equal(t, "normal", spec.ChartAppearance.Stack.ValueOrDefault())
+			assert.True(t, spec.ChartAppearance.Percentiles.Enabled)
+			assert.Equal(t, []float64{50, 90, 99}, spec.ChartAppearance.Percentiles.Values)
+
+			stored, err := json.Marshal(spec)
+			require.NoError(t, err)
+			assert.Contains(t, string(stored), `"stack":"normal"`)
+		})
+	}
+}
+
+func TestDistributionPanelSpecPercentileValues(t *testing.T) {
+	testCases := []struct {
+		name            string
+		spec            string
+		expectedEnabled bool
+		expectedValues  []float64
+	}{
+		{name: "Disabled_KeepsDefaultValues", spec: `{"chartAppearance": {"percentiles": {"enabled": false}}}`, expectedEnabled: false, expectedValues: []float64{50, 90, 99}},
+		{name: "EmptyValues_MarksNone", spec: `{"chartAppearance": {"percentiles": {"values": []}}}`, expectedEnabled: true, expectedValues: []float64{}},
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			var plugin PanelPlugin
+			require.NoError(t, json.Unmarshal([]byte(`{"kind": "signoz/DistributionPanel", "spec": `+testCase.spec+`}`), &plugin))
+
+			spec := plugin.Spec.(*DistributionPanelSpec)
+			assert.Equal(t, testCase.expectedEnabled, spec.ChartAppearance.Percentiles.Enabled)
+			assert.Equal(t, testCase.expectedValues, spec.ChartAppearance.Percentiles.Values)
+		})
+	}
+}
+
+func TestDistributionPanelSpecXMinEqualsMax(t *testing.T) {
+	var plugin PanelPlugin
+	require.NoError(t, json.Unmarshal([]byte(`{"kind": "signoz/DistributionPanel", "spec": {"axes": {"x": {"min": 10, "max": 10}}}}`), &plugin))
+
+	spec := plugin.Spec.(*DistributionPanelSpec)
+	require.NotNil(t, spec.Axes.X.Min)
+	require.NotNil(t, spec.Axes.X.Max)
+	assert.Equal(t, 10.0, *spec.Axes.X.Min)
+	assert.Equal(t, 10.0, *spec.Axes.X.Max)
+}
+
+func TestDistributionPanelSpecRejections(t *testing.T) {
+	testCases := []struct {
+		name            string
+		spec            string
+		expectedMessage string
+	}{
+		{
+			name:            "XMin_AboveMax",
+			spec:            `{"axes": {"x": {"min": 20, "max": 10}}}`,
+			expectedMessage: "axes.x.min 20 is greater than axes.x.max 10",
+		},
+		{
+			name:            "YScale_Unknown",
+			spec:            `{"axes": {"y": {"scale": "symlog"}}}`,
+			expectedMessage: "invalid distribution y scale",
+		},
+		{
+			name:            "UnknownField",
+			spec:            `{"axes": {"y": {"softMax": 10}}}`,
+			expectedMessage: "unknown field \"softMax\"",
+		},
+		{
+			name:            "Percentile_Zero",
+			spec:            `{"chartAppearance": {"percentiles": {"values": [0, 50]}}}`,
+			expectedMessage: "0 is not in (0, 100)",
+		},
+		{
+			name:            "Percentile_Hundred",
+			spec:            `{"chartAppearance": {"percentiles": {"values": [100]}}}`,
+			expectedMessage: "100 is not in (0, 100)",
+		},
+		{
+			name:            "Percentile_Duplicate",
+			spec:            `{"chartAppearance": {"percentiles": {"values": [90, 90]}}}`,
+			expectedMessage: "90 is listed more than once",
+		},
+		{
+			name:            "Percentiles_MoreThanFive",
+			spec:            `{"chartAppearance": {"percentiles": {"values": [10, 25, 50, 75, 90, 99]}}}`,
+			expectedMessage: "at most 5 percentiles",
+		},
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			var plugin PanelPlugin
+			err := json.Unmarshal([]byte(`{"kind": "signoz/DistributionPanel", "spec": `+testCase.spec+`}`), &plugin)
+			require.Error(t, err)
+			assert.Contains(t, err.Error(), testCase.expectedMessage)
+		})
+	}
+}
+
+func TestDistributionPanelQueryKinds(t *testing.T) {
+	testCases := []struct {
+		name            string
+		queryPluginKind string
+		queryPluginSpec string
+		expectedAllowed bool
+	}{
+		{
+			name:            "PromQL_Allowed",
+			queryPluginKind: "signoz/PromQLQuery",
+			queryPluginSpec: `{"name": "A", "query": "sum by (le) (increase(signoz_latency_bucket[5m]))"}`,
+			expectedAllowed: true,
+		},
+		{
+			name:            "ClickHouseSQL_Allowed",
+			queryPluginKind: "signoz/ClickHouseSQL",
+			queryPluginSpec: `{"name": "A", "query": "SELECT ts, bucket, value FROM cells"}`,
+			expectedAllowed: true,
+		},
+		{
+			name:            "TraceOperator_Refused",
+			queryPluginKind: "signoz/TraceOperator",
+			queryPluginSpec: `{"name": "T1", "expression": "A => B"}`,
+			expectedAllowed: false,
+		},
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			data := fmt.Sprintf(`{
+				"variables": [],
+				"panels": {
+					"p1": {
+						"kind": "Panel",
+						"spec": {
+							"links": [],
+							"plugin": {"kind": "signoz/DistributionPanel", "spec": {}},
+							"queries": [{
+								"kind": "distribution",
+								"spec": {
+									"plugin": {"kind": %q, "spec": %s}
+								}
+							}]
+						}
+					}
+				},
+				"links": [],
+				"layouts": []
+			}`, testCase.queryPluginKind, testCase.queryPluginSpec)
+
+			_, err := unmarshalDashboard([]byte(data))
+
+			if testCase.expectedAllowed {
+				require.NoError(t, err)
+				return
+			}
+
+			require.Error(t, err)
+			assert.Contains(t, err.Error(), "is not supported by panel kind")
+		})
+	}
+}
+
 func TestInvalidateOneInvalidPanel(t *testing.T) {
 	data := []byte(`{
 		"variables": [],

pkg/types/dashboardtypes/perses_plugin_wrappers.go

@@ -28,17 +28,18 @@ type PanelPlugin struct {
 // (and strips the duplicate parent properties) after reflection.
 func (PanelPlugin) PrepareJSONSchema(s *jsonschema.Schema) error {
 	return markDiscriminator(s, "kind", map[string]string{
-		string(PanelKindTimeSeries):  schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTimeSeriesPanelSpec"),
-		string(PanelKindBarChart):    schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesBarChartPanelSpec"),
-		string(PanelKindAreaChart):   schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesAreaChartPanelSpec"),
-		string(PanelKindNumber):      schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesNumberPanelSpec"),
-		string(PanelKindPieChart):    schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesPieChartPanelSpec"),
-		string(PanelKindTable):       schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTablePanelSpec"),
-		string(PanelKindHistogram):   schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesHistogramPanelSpec"),
-		string(PanelKindList):        schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesListPanelSpec"),
-		string(PanelKindText):        schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTextPanelSpec"),
-		string(PanelKindHeatmap):     schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesHeatmapPanelSpec"),
-		string(PanelKindScatterPlot): schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesScatterPlotPanelSpec"),
+		string(PanelKindTimeSeries):   schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTimeSeriesPanelSpec"),
+		string(PanelKindBarChart):     schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesBarChartPanelSpec"),
+		string(PanelKindAreaChart):    schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesAreaChartPanelSpec"),
+		string(PanelKindNumber):       schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesNumberPanelSpec"),
+		string(PanelKindPieChart):     schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesPieChartPanelSpec"),
+		string(PanelKindTable):        schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTablePanelSpec"),
+		string(PanelKindHistogram):    schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesHistogramPanelSpec"),
+		string(PanelKindList):         schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesListPanelSpec"),
+		string(PanelKindText):         schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesTextPanelSpec"),
+		string(PanelKindHeatmap):      schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesHeatmapPanelSpec"),
+		string(PanelKindScatterPlot):  schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesScatterPlotPanelSpec"),
+		string(PanelKindDistribution): schemaRef("DashboardtypesPanelPluginVariantGithubComSigNozSignozPkgTypesDashboardtypesDistributionPanelSpec"),
 	})
 }
 
@@ -73,6 +74,7 @@ func (PanelPlugin) JSONSchemaOneOf() []any {
 		PanelPluginVariant[TextPanelSpec]{Kind: string(PanelKindText)},
 		PanelPluginVariant[HeatmapPanelSpec]{Kind: string(PanelKindHeatmap)},
 		PanelPluginVariant[ScatterPlotPanelSpec]{Kind: string(PanelKindScatterPlot)},
+		PanelPluginVariant[DistributionPanelSpec]{Kind: string(PanelKindDistribution)},
 	}
 }
 
@@ -236,17 +238,18 @@ func (v VariablePluginVariant[S]) PrepareJSONSchema(s *jsonschema.Schema) error
 
 var (
 	panelPluginSpecs = map[PanelPluginKind]func() any{
-		PanelKindTimeSeries:  func() any { return new(TimeSeriesPanelSpec) },
-		PanelKindBarChart:    func() any { return new(BarChartPanelSpec) },
-		PanelKindAreaChart:   func() any { return new(AreaChartPanelSpec) },
-		PanelKindNumber:      func() any { return new(NumberPanelSpec) },
-		PanelKindPieChart:    func() any { return new(PieChartPanelSpec) },
-		PanelKindTable:       func() any { return new(TablePanelSpec) },
-		PanelKindHistogram:   func() any { return new(HistogramPanelSpec) },
-		PanelKindList:        func() any { return new(ListPanelSpec) },
-		PanelKindText:        func() any { return new(TextPanelSpec) },
-		PanelKindHeatmap:     func() any { return new(HeatmapPanelSpec) },
-		PanelKindScatterPlot: func() any { return new(ScatterPlotPanelSpec) },
+		PanelKindTimeSeries:   func() any { return new(TimeSeriesPanelSpec) },
+		PanelKindBarChart:     func() any { return new(BarChartPanelSpec) },
+		PanelKindAreaChart:    func() any { return new(AreaChartPanelSpec) },
+		PanelKindNumber:       func() any { return new(NumberPanelSpec) },
+		PanelKindPieChart:     func() any { return new(PieChartPanelSpec) },
+		PanelKindTable:        func() any { return new(TablePanelSpec) },
+		PanelKindHistogram:    func() any { return new(HistogramPanelSpec) },
+		PanelKindList:         func() any { return new(ListPanelSpec) },
+		PanelKindText:         func() any { return new(TextPanelSpec) },
+		PanelKindHeatmap:      func() any { return new(HeatmapPanelSpec) },
+		PanelKindScatterPlot:  func() any { return new(ScatterPlotPanelSpec) },
+		PanelKindDistribution: func() any { return new(DistributionPanelSpec) },
 	}
 	queryPluginSpecs = map[QueryPluginKind]func() any{
 		QueryKindBuilder:       func() any { return new(BuilderQuerySpec) },
@@ -263,17 +266,18 @@ var (
 		VariableKindCustom:  func() any { return new(CustomVariableSpec) },
 	}
 	allowedQueryKinds = map[PanelPluginKind][]QueryPluginKind{
-		PanelKindTimeSeries:  {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindPromQL, QueryKindClickHouseSQL},
-		PanelKindBarChart:    {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindPromQL, QueryKindClickHouseSQL},
-		PanelKindAreaChart:   {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindPromQL, QueryKindClickHouseSQL},
-		PanelKindNumber:      {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindPromQL, QueryKindClickHouseSQL},
-		PanelKindHistogram:   {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindPromQL, QueryKindClickHouseSQL},
-		PanelKindPieChart:    {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindClickHouseSQL},
-		PanelKindTable:       {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindClickHouseSQL},
-		PanelKindList:        {QueryKindBuilder, QueryKindAIBuilder},
-		PanelKindText:        {},
-		PanelKindHeatmap:     {QueryKindBuilder, QueryKindComposite, QueryKindFormula, QueryKindPromQL, QueryKindClickHouseSQL},
-		PanelKindScatterPlot: {QueryKindBuilder, QueryKindComposite, QueryKindFormula, QueryKindClickHouseSQL},
+		PanelKindTimeSeries:   {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindPromQL, QueryKindClickHouseSQL},
+		PanelKindBarChart:     {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindPromQL, QueryKindClickHouseSQL},
+		PanelKindAreaChart:    {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindPromQL, QueryKindClickHouseSQL},
+		PanelKindNumber:       {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindPromQL, QueryKindClickHouseSQL},
+		PanelKindHistogram:    {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindPromQL, QueryKindClickHouseSQL},
+		PanelKindPieChart:     {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindClickHouseSQL},
+		PanelKindTable:        {QueryKindBuilder, QueryKindAIBuilder, QueryKindComposite, QueryKindFormula, QueryKindTraceOperator, QueryKindClickHouseSQL},
+		PanelKindList:         {QueryKindBuilder, QueryKindAIBuilder},
+		PanelKindText:         {},
+		PanelKindHeatmap:      {QueryKindBuilder, QueryKindComposite, QueryKindFormula, QueryKindPromQL, QueryKindClickHouseSQL},
+		PanelKindScatterPlot:  {QueryKindBuilder, QueryKindComposite, QueryKindFormula, QueryKindClickHouseSQL},
+		PanelKindDistribution: {QueryKindBuilder, QueryKindComposite, QueryKindFormula, QueryKindPromQL, QueryKindClickHouseSQL},
 	}
 )
 

pkg/types/dashboardtypes/perses_replicas.go

@@ -70,7 +70,7 @@ func (k *PanelKind) UnmarshalJSON(data []byte) error {
 
 type PanelSpec struct {
 	Display Display     `json:"display" required:"true" description:"The panel title and description."`
-	Plugin  PanelPlugin `json:"plugin" required:"true" description:"The visualization: kind is one of signoz/TimeSeriesPanel, signoz/BarChartPanel, signoz/AreaChartPanel, signoz/NumberPanel, signoz/PieChartPanel, signoz/TablePanel, signoz/HistogramPanel, signoz/ListPanel, signoz/TextPanel or signoz/HeatmapPanel, and spec holds that kind's options ({} accepts every default)."`
+	Plugin  PanelPlugin `json:"plugin" required:"true" description:"The visualization: kind is one of signoz/TimeSeriesPanel, signoz/BarChartPanel, signoz/AreaChartPanel, signoz/NumberPanel, signoz/PieChartPanel, signoz/TablePanel, signoz/HistogramPanel, signoz/ListPanel, signoz/TextPanel, signoz/HeatmapPanel or signoz/DistributionPanel, and spec holds that kind's options ({} accepts every default)."`
 	Queries []Query     `json:"queries" required:"true" nullable:"false" description:"The queries the panel runs. Use exactly one entry for a data panel and [] for signoz/TextPanel. To run several named queries or formulas, use one entry whose spec.plugin.kind is signoz/CompositeQuery and put the constituent queries in its plugin spec."`
 	Links   []Link      `json:"links,omitzero" description:"Context links offered in the data point drilldown menu of the panel, with dashboard variables resolved in the URL."`
 }
@@ -92,13 +92,13 @@ type Link struct {
 // ══════════════════════════════════════════════
 
 type Query struct {
-	Kind qb.RequestType `json:"kind" required:"true" description:"The result shape the panel requests: time_series for time series, bar, area and histogram panels, scalar for number, table and pie panels, raw for list panels, heatmap for heatmap panels, trace for trace panels."`
+	Kind qb.RequestType `json:"kind" required:"true" description:"The result shape the panel requests: time_series for time series, bar, area and histogram panels, scalar for number, table and pie panels, raw for list panels, heatmap for heatmap panels, distribution for distribution panels, trace for trace panels."`
 	Spec QuerySpec      `json:"spec" required:"true" description:"The query content: an optional name and the query plugin."`
 }
 
 type QuerySpec struct {
 	Name   string      `json:"name,omitempty" description:"An optional label for the query. The name queries refer to each other by lives in the plugin spec."`
-	Plugin QueryPlugin `json:"plugin" required:"true" description:"The query: kind is one of signoz/BuilderQuery, signoz/AIBuilderQuery (builder query over AI observability traces), signoz/CompositeQuery (several named queries and formulas), signoz/Formula, signoz/PromQLQuery, signoz/ClickHouseSQL or signoz/TraceOperator, and spec holds that kind's query. Pie and table panels reject signoz/PromQLQuery; heatmap panels reject signoz/AIBuilderQuery and signoz/TraceOperator; list panels accept only signoz/BuilderQuery and signoz/AIBuilderQuery."`
+	Plugin QueryPlugin `json:"plugin" required:"true" description:"The query: kind is one of signoz/BuilderQuery, signoz/AIBuilderQuery (builder query over AI observability traces), signoz/CompositeQuery (several named queries and formulas), signoz/Formula, signoz/PromQLQuery, signoz/ClickHouseSQL or signoz/TraceOperator, and spec holds that kind's query. Pie and table panels reject signoz/PromQLQuery; heatmap and distribution panels reject signoz/AIBuilderQuery and signoz/TraceOperator; list panels accept only signoz/BuilderQuery and signoz/AIBuilderQuery."`
 }
 
 // ══════════════════════════════════════════════

pkg/types/dashboardtypes/perses_signoz_plugins.go

@@ -189,21 +189,22 @@ func (AIBuilderQuerySpec) PrepareJSONSchema(s *jsonschema.Schema) error {
 type PanelPluginKind string
 
 const (
-	PanelKindTimeSeries  PanelPluginKind = "signoz/TimeSeriesPanel"
-	PanelKindBarChart    PanelPluginKind = "signoz/BarChartPanel"
-	PanelKindAreaChart   PanelPluginKind = "signoz/AreaChartPanel"
-	PanelKindNumber      PanelPluginKind = "signoz/NumberPanel"
-	PanelKindPieChart    PanelPluginKind = "signoz/PieChartPanel"
-	PanelKindTable       PanelPluginKind = "signoz/TablePanel"
-	PanelKindHistogram   PanelPluginKind = "signoz/HistogramPanel"
-	PanelKindList        PanelPluginKind = "signoz/ListPanel"
-	PanelKindText        PanelPluginKind = "signoz/TextPanel"
-	PanelKindHeatmap     PanelPluginKind = "signoz/HeatmapPanel"
-	PanelKindScatterPlot PanelPluginKind = "signoz/ScatterPlotPanel"
+	PanelKindTimeSeries   PanelPluginKind = "signoz/TimeSeriesPanel"
+	PanelKindBarChart     PanelPluginKind = "signoz/BarChartPanel"
+	PanelKindAreaChart    PanelPluginKind = "signoz/AreaChartPanel"
+	PanelKindNumber       PanelPluginKind = "signoz/NumberPanel"
+	PanelKindPieChart     PanelPluginKind = "signoz/PieChartPanel"
+	PanelKindTable        PanelPluginKind = "signoz/TablePanel"
+	PanelKindHistogram    PanelPluginKind = "signoz/HistogramPanel"
+	PanelKindList         PanelPluginKind = "signoz/ListPanel"
+	PanelKindText         PanelPluginKind = "signoz/TextPanel"
+	PanelKindHeatmap      PanelPluginKind = "signoz/HeatmapPanel"
+	PanelKindScatterPlot  PanelPluginKind = "signoz/ScatterPlotPanel"
+	PanelKindDistribution PanelPluginKind = "signoz/DistributionPanel"
 )
 
 func (PanelPluginKind) Enum() []any {
-	return []any{PanelKindTimeSeries, PanelKindBarChart, PanelKindAreaChart, PanelKindNumber, PanelKindPieChart, PanelKindTable, PanelKindHistogram, PanelKindList, PanelKindText, PanelKindHeatmap, PanelKindScatterPlot}
+	return []any{PanelKindTimeSeries, PanelKindBarChart, PanelKindAreaChart, PanelKindNumber, PanelKindPieChart, PanelKindTable, PanelKindHistogram, PanelKindList, PanelKindText, PanelKindHeatmap, PanelKindScatterPlot, PanelKindDistribution}
 }
 
 func (k PanelPluginKind) rendersWithoutQuery() bool {
@@ -346,6 +347,89 @@ func (c HeatmapColors) validate() error {
 	return nil
 }
 
+type DistributionPanelSpec struct {
+	Visualization   BasicVisualization          `json:"visualization" description:"The time range the bucket counts are summed over."`
+	Formatting      PanelFormatting             `json:"formatting" description:"Unit and decimal precision of the bucket bounds; counts take no unit."`
+	Axes            DistributionAxes            `json:"axes" description:"The X (bucket) axis range and Y (count) axis scale."`
+	Legend          Legend                      `json:"legend" description:"Legend placement and series colors."`
+	ChartAppearance DistributionChartAppearance `json:"chartAppearance" description:"Stacking and percentile markers."`
+}
+
+// UnmarshalJSON decodes over the defaults, since the stack default (normal)
+// differs from StackMode's own and percentile markers default to on.
+func (spec *DistributionPanelSpec) UnmarshalJSON(data []byte) error {
+	type alias DistributionPanelSpec
+	tmp := alias{ChartAppearance: DistributionChartAppearance{
+		Stack:       StackModeNormal,
+		Percentiles: DistributionPercentiles{Enabled: true, Values: []float64{50, 90, 99}},
+	}}
+	dec := json.NewDecoder(bytes.NewReader(data))
+	dec.DisallowUnknownFields()
+	if err := dec.Decode(&tmp); err != nil {
+		return err
+	}
+	*spec = DistributionPanelSpec(tmp)
+	return nil
+}
+
+func (spec *DistributionPanelSpec) validate() error {
+	if err := spec.Axes.X.validate(); err != nil {
+		return err
+	}
+	return spec.ChartAppearance.Percentiles.validate()
+}
+
+type DistributionAxes struct {
+	X DistributionXAxis `json:"x" description:"The bucket axis."`
+	Y DistributionYAxis `json:"y" description:"The count axis."`
+}
+
+// DistributionXAxis draws every bucket equally wide, whatever its bounds.
+type DistributionXAxis struct {
+	Min *float64 `json:"min" description:"Buckets wholly below this value are hidden. Null shows them all."`
+	Max *float64 `json:"max" description:"Buckets wholly above this value are hidden. Null shows them all."`
+}
+
+func (axis DistributionXAxis) validate() error {
+	if axis.Min != nil && axis.Max != nil && *axis.Min > *axis.Max {
+		return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "axes.x.min %v is greater than axes.x.max %v", *axis.Min, *axis.Max)
+	}
+	return nil
+}
+
+type DistributionYAxis struct {
+	Scale DistributionYScale `json:"scale" required:"true" description:"How counts are spaced: linear (default) or log."`
+}
+
+type DistributionChartAppearance struct {
+	Stack       StackMode               `json:"stack" required:"true" description:"How groups combine in a bucket: normal (default) stacks them, none draws them side by side, percent stacks them as shares of the bucket."`
+	Percentiles DistributionPercentiles `json:"percentiles" description:"Percentile markers drawn across the bucket axis."`
+}
+
+const maxDistributionPercentiles = 5
+
+type DistributionPercentiles struct {
+	Enabled bool      `json:"enabled" required:"true" description:"Whether percentile markers are drawn. Defaults to true."`
+	Values  []float64 `json:"values" required:"true" description:"The percentiles to mark, each in (0, 100), at most 5, no duplicates. Defaults to [50, 90, 99]."`
+}
+
+func (percentiles DistributionPercentiles) validate() error {
+	if len(percentiles.Values) > maxDistributionPercentiles {
+		return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "chartAppearance.percentiles.values: at most %d percentiles, got %d", maxDistributionPercentiles, len(percentiles.Values))
+	}
+	seen := make(map[float64]struct{}, len(percentiles.Values))
+	for _, value := range percentiles.Values {
+		if value <= 0 || value >= 100 {
+			return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "chartAppearance.percentiles.values: %v is not in (0, 100)", value)
+		}
+		if _, ok := seen[value]; ok {
+			return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "chartAppearance.percentiles.values: %v is listed more than once", value)
+		}
+		seen[value] = struct{}{}
+	}
+	return nil
+}
+
 type TextPanelSpec struct {
 	Mode          TextMode         `json:"mode" description:"How text is interpreted. Only markdown is supported."`
 	Text          string           `json:"text" description:"The content to render."`
@@ -1462,6 +1546,43 @@ func (s *HeatmapYScale) UnmarshalJSON(data []byte) error {
 	}
 }
 
+type DistributionYScale struct{ valuer.String }
+
+var (
+	DistributionYScaleLinear = DistributionYScale{valuer.NewString("linear")} // default
+	DistributionYScaleLog    = DistributionYScale{valuer.NewString("log")}
+)
+
+func (DistributionYScale) Enum() []any {
+	return []any{DistributionYScaleLinear, DistributionYScaleLog}
+}
+
+func (scale DistributionYScale) ValueOrDefault() string {
+	if scale.IsZero() {
+		return DistributionYScaleLinear.StringValue()
+	}
+	return scale.StringValue()
+}
+
+func (scale DistributionYScale) MarshalJSON() ([]byte, error) {
+	return json.Marshal(scale.ValueOrDefault())
+}
+
+func (scale *DistributionYScale) UnmarshalJSON(data []byte) error {
+	var v string
+	if err := json.Unmarshal(data, &v); err != nil {
+		return errors.WrapInvalidInputf(err, ErrCodeDashboardInvalidInput, "invalid distribution y scale: must be a string, one of `linear` or `log`")
+	}
+	parsed := DistributionYScale{valuer.NewString(v)}
+	switch parsed {
+	case DistributionYScaleLinear, DistributionYScaleLog:
+		*scale = parsed
+		return nil
+	default:
+		return errors.NewInvalidInputf(ErrCodeDashboardInvalidInput, "invalid distribution y scale %q: must be `linear` or `log`", v)
+	}
+}
+
 type HeatmapColorScale struct{ valuer.String }
 
 var (

pkg/types/dashboardtypes/testdata/perses_distribution_panel.json

@@ -0,0 +1,95 @@
+{
+  "display": {
+    "name": "latency",
+    "description": "how request duration is distributed over the range"
+  },
+  "variables": [],
+  "panels": {
+    "p1": {
+      "kind": "Panel",
+      "spec": {
+        "display": {
+          "name": "request duration",
+          "description": ""
+        },
+        "plugin": {
+          "kind": "signoz/DistributionPanel",
+          "spec": {
+            "visualization": {
+              "timePreference": "global_time"
+            },
+            "formatting": {
+              "unit": "s",
+              "decimalPrecision": "3"
+            },
+            "axes": {
+              "x": {
+                "min": 10
+              },
+              "y": {
+                "scale": "log"
+              }
+            },
+            "legend": {
+              "position": "right",
+              "mode": "list"
+            },
+            "chartAppearance": {
+              "stack": "none",
+              "percentiles": {
+                "enabled": true,
+                "values": [75, 99.9]
+              }
+            }
+          }
+        },
+        "links": [],
+        "queries": [
+          {
+            "kind": "distribution",
+            "spec": {
+              "plugin": {
+                "kind": "signoz/BuilderQuery",
+                "spec": {
+                  "name": "A",
+                  "signal": "metrics",
+                  "aggregations": [
+                    {
+                      "metricName": "http.server.request.duration",
+                      "timeAggregation": "increase",
+                      "spaceAggregation": "sum"
+                    }
+                  ],
+                  "groupBy": [
+                    {
+                      "name": "service.name"
+                    }
+                  ]
+                }
+              }
+            }
+          }
+        ]
+      }
+    }
+  },
+  "links": [],
+  "layouts": [
+    {
+      "kind": "Grid",
+      "spec": {
+        "items": [
+          {
+            "x": 0,
+            "y": 0,
+            "width": 12,
+            "height": 8,
+            "content": {
+              "$ref": "#/spec/panels/p1"
+            }
+          }
+        ]
+      }
+    }
+  ]
+}