chore(charts): drop stackUtils, superseded by stackSeriesUtils

Nothing imported it but its own test: every caller uses stackSeriesUtils,
whose stackSeries() is the same algorithm with the mode parameter, and
whose band helpers are byte-identical copies. Its getInitialStackedBands
was the last remaining copy of the API this branch replaced with bands
derived in the config builder.

frontend/src/container/BillingContainer/BillingUsageGraph/BillingUsageGraph.tsx

@@ -5,6 +5,7 @@ import BarChart from 'container/DashboardContainer/visualization/charts/BarChart
 import { useIsDarkMode } from 'hooks/useDarkMode';
 import { useResizeObserver } from 'hooks/useDimensions';
 import { prepareChartData } from 'lib/uPlotV2/utils/dataUtils';
+import { StackMode } from 'lib/uPlotV2/config/types';
 import {
 	LegendPosition,
 	TooltipRenderArgs,
@@ -131,9 +132,9 @@ export function BillingUsageGraph(props: BillingUsageGraphProps): JSX.Element {
 			<div ref={graphRef} className={styles.graphContainer}>
 				{containerDimensions.width > 0 && containerDimensions.height > 0 && (
 					<BarChart
+						stack={StackMode.Normal}
 						config={config}
 						data={chartData}
-						isStackedBarChart
 						legendConfig={{ position: LegendPosition.BOTTOM }}
 						customTooltip={renderBillingTooltip}
 						width={containerDimensions.width}

frontend/src/container/BillingContainer/BillingUsageGraph/__tests__/prepareBillingBarConfig.test.ts

@@ -58,26 +58,17 @@ describe('prepareBillingBarConfig', () => {
 		expect(config.series?.[4]?.stroke).toBe(Color.BG_AMBER_500);
 	});
 
-	it('sets stacking bands, padding, and focus alpha for behavioral parity', () => {
+	it('sets padding and focus alpha for behavioral parity', () => {
 		const builder = prepareBillingBarConfig({
 			...baseProps,
 			apiResponse: makeApiResponse(['Logs', 'Traces', 'Metrics']),
 		});
 		const config = builder.getConfig();
-		expect(config.bands).toStrictEqual([{ series: [1, 2] }, { series: [2, 3] }]);
+		// Stacking bands come from the chart now — see useChartStacking.
 		expect(config.padding).toStrictEqual([32, 32, 16, 16]);
 		expect(config.focus).toStrictEqual({ alpha: 0.3 });
 	});
 
-	it('sets no bands when result is empty', () => {
-		const builder = prepareBillingBarConfig({
-			...baseProps,
-			apiResponse: makeApiResponse([]),
-		});
-		const config = builder.getConfig();
-		expect(config.bands).toBeUndefined();
-	});
-
 	it('uses queryName as label when legend is undefined', () => {
 		const apiResponse: MetricRangePayloadProps = {
 			data: {

frontend/src/container/BillingContainer/BillingUsageGraph/prepareBillingBarConfig.ts

@@ -1,7 +1,6 @@
 import { Color } from '@signozhq/design-tokens';
 import type { Timezone } from 'components/CustomTimePicker/timezoneUtils';
 import { PANEL_TYPES } from 'constants/queryBuilder';
-import { getInitialStackedBands } from 'container/DashboardContainer/visualization/charts/utils/stackSeriesUtils';
 import { buildBaseConfig } from 'container/DashboardContainer/visualization/panels/utils/baseConfigBuilder';
 import { DrawStyle } from 'lib/uPlotV2/config/types';
 import type { UPlotConfigBuilder } from 'lib/uPlotV2/config/UPlotConfigBuilder';
@@ -63,7 +62,6 @@ export function prepareBillingBarConfig({
 		});
 	});
 
-	builder.setBands(getInitialStackedBands(results.length));
 	builder.setPadding([32, 32, 16, 16]);
 	builder.setFocus({ alpha: 0.3 });
 

frontend/src/container/DashboardContainer/visualization/charts/BarChart/BarChart.tsx

@@ -6,25 +6,24 @@ import {
 	TooltipRenderArgs,
 } from 'lib/uPlotV2/components/types';
 
-import { useBarChartStacking } from '../../hooks/useBarChartStacking';
+import { StackMode } from 'lib/uPlotV2/config/types';
+
 import { BarChartProps } from '../types';
 
 export default function BarChart(props: BarChartProps): JSX.Element {
 	const {
 		children,
-		isStackedBarChart,
 		customTooltip,
 		config,
 		data,
+		stack = StackMode.None,
 		pinnedTooltipElement,
 		...rest
 	} = props;
 
-	const chartData = useBarChartStacking({
-		data,
-		isStackedBarChart,
-		config,
-	});
+	// Written during render so it lands before UPlotChart's effect reads the config,
+	// which derives the fill bands, percent axis unit and percent range from it.
+	config.setStackMode(stack);
 
 	const renderTooltip = useCallback(
 		(props: TooltipRenderArgs): React.ReactNode => {
@@ -37,7 +36,6 @@ export default function BarChart(props: BarChartProps): JSX.Element {
 				timezone: rest.timezone,
 				yAxisUnit: rest.yAxisUnit,
 				decimalPrecision: rest.decimalPrecision,
-				isStackedBarChart: isStackedBarChart,
 				canPinTooltip: rest.canPinTooltip,
 				renderTooltipFooter: rest.renderTooltipFooter,
 			};
@@ -48,7 +46,6 @@ export default function BarChart(props: BarChartProps): JSX.Element {
 			rest.timezone,
 			rest.yAxisUnit,
 			rest.decimalPrecision,
-			isStackedBarChart,
 			rest.canPinTooltip,
 			rest.renderTooltipFooter,
 		],
@@ -58,7 +55,7 @@ export default function BarChart(props: BarChartProps): JSX.Element {
 		<ChartWrapper
 			{...rest}
 			config={config}
-			data={chartData}
+			data={data}
 			customTooltip={renderTooltip}
 			pinnedTooltipElement={pinnedTooltipElement}
 		>

frontend/src/container/DashboardContainer/visualization/charts/ChartWrapper/ChartWrapper.tsx

@@ -6,12 +6,15 @@ import {
 	TooltipRenderArgs,
 } from 'lib/uPlotV2/components/types';
 import UPlotChart from 'lib/uPlotV2/components/UPlotChart/UPlotChart';
+import { StackMode } from 'lib/uPlotV2/config/types';
+import { prepareAlignedData } from 'lib/uPlotV2/components/UPlotChart/utils';
 import { PlotContextProvider } from 'lib/uPlotV2/context/PlotContext';
 import TooltipPlugin from 'lib/uPlotV2/plugins/TooltipPlugin/TooltipPlugin';
 import noop from 'lodash-es/noop';
 import uPlot from 'uplot';
 
-import { ChartProps } from '../types';
+import { ChartWrapperProps } from '../types';
+import { useChartStacking } from './useChartStacking';
 
 const TOOLTIP_WIDTH_PADDING = 120;
 const TOOLTIP_MIN_WIDTH = 300;
@@ -39,9 +42,20 @@ export default function ChartWrapper({
 	pinnedTooltipElement,
 	tooltipPortalRoot,
 	'data-testid': testId,
-}: ChartProps): JSX.Element {
+}: ChartWrapperProps): JSX.Element {
 	const plotInstanceRef = useRef<uPlot | null>(null);
 
+	const stack = config.getStackMode();
+	const chartData = useChartStacking({ data, config });
+
+	// Tooltips need pre-stack values, gap-processed exactly as UPlotChart processes the
+	// plot data — otherwise the cursor's index addresses a shorter array.
+	const unstackedData = useMemo(
+		() =>
+			stack === StackMode.None ? undefined : prepareAlignedData({ data, config }),
+		[data, config, stack],
+	);
+
 	const legendComponent = useCallback(
 		(averageLegendWidth: number): React.ReactNode => {
 			if (!showLegend) {
@@ -61,11 +75,11 @@ export default function ChartWrapper({
 	const renderTooltipCallback = useCallback(
 		(args: TooltipRenderArgs): React.ReactNode => {
 			if (customTooltip) {
-				return customTooltip(args);
+				return customTooltip({ ...args, unstackedData });
 			}
 			return null;
 		},
-		[customTooltip],
+		[customTooltip, unstackedData],
 	);
 
 	const syncMetadata = useMemo(
@@ -91,7 +105,7 @@ export default function ChartWrapper({
 				{({ chartWidth, chartHeight, averageLegendWidth }): JSX.Element => (
 					<UPlotChart
 						config={config}
-						data={data}
+						data={chartData}
 						width={chartWidth}
 						height={chartHeight}
 						plotRef={(plot): void => {

frontend/src/container/DashboardContainer/visualization/charts/ChartWrapper/__tests__/useChartStacking.test.ts

@@ -0,0 +1,98 @@
+import { renderHook } from '@testing-library/react';
+import { UPlotConfigBuilder } from 'lib/uPlotV2/config/UPlotConfigBuilder';
+import { StackMode } from 'lib/uPlotV2/config/types';
+import uPlot from 'uplot';
+
+import { useChartStacking } from '../useChartStacking';
+
+type Hooks = Record<string, (...args: unknown[]) => void>;
+
+function createConfig(stack: StackMode): {
+	config: UPlotConfigBuilder;
+	hooks: Hooks;
+} {
+	const hooks: Hooks = {};
+	const config = {
+		getStackMode: (): StackMode => stack,
+		addHook: jest.fn((type: string, hook: (...args: unknown[]) => void) => {
+			hooks[type] = hook;
+			return jest.fn();
+		}),
+	} as unknown as UPlotConfigBuilder;
+	return { config, hooks };
+}
+
+const data = [[1], [30], [10]] as unknown as uPlot.AlignedData;
+
+describe('useChartStacking', () => {
+	it('returns the data untouched and registers nothing when the config says `none`', () => {
+		const { config } = createConfig(StackMode.None);
+		const { result } = renderHook(() => useChartStacking({ data, config }));
+
+		expect(result.current).toBe(data);
+		expect(config.addHook).not.toHaveBeenCalled();
+	});
+
+	it('treats a missing config as unstacked', () => {
+		const { result } = renderHook(() => useChartStacking({ data, config: null }));
+
+		expect(result.current).toBe(data);
+	});
+
+	it('accumulates raw values when the config declares `normal`', () => {
+		const { config } = createConfig(StackMode.Normal);
+		const { result } = renderHook(() => useChartStacking({ data, config }));
+
+		expect(result.current).toStrictEqual([[1], [40], [10]]);
+	});
+
+	it('rescales each column to its total when the config declares `percent`', () => {
+		const { config } = createConfig(StackMode.Percent);
+		const { result } = renderHook(() => useChartStacking({ data, config }));
+
+		expect(result.current).toStrictEqual([[1], [100], [25]]);
+	});
+
+	it('registers the uPlot hooks that re-stack on data and visibility changes', () => {
+		const { config } = createConfig(StackMode.Normal);
+		renderHook(() => useChartStacking({ data, config }));
+
+		expect(
+			(config.addHook as jest.Mock).mock.calls.map(([type]) => type),
+		).toStrictEqual(['setData', 'setSeries']);
+	});
+
+	it('re-stacks from the raw values when the legend hides a series', () => {
+		const { config, hooks } = createConfig(StackMode.Normal);
+		renderHook(() => useChartStacking({ data, config }));
+
+		const plot = {
+			data: [[1]],
+			series: [{}, { show: true }, { show: false }],
+			delBand: jest.fn(),
+			addBand: jest.fn(),
+			setData: jest.fn(),
+		};
+		hooks.setSeries(plot, 2, { show: false });
+
+		// The hidden series keeps its raw value and stops contributing to the total.
+		expect(plot.setData).toHaveBeenCalledWith([[1], [30], [10]]);
+		expect(plot.delBand).toHaveBeenCalledWith(null);
+	});
+
+	it('ignores a focus-only setSeries so hovering does not re-stack', () => {
+		const { config, hooks } = createConfig(StackMode.Normal);
+		renderHook(() => useChartStacking({ data, config }));
+
+		const plot = {
+			data: [[1]],
+			series: [{}, { show: true }, { show: true }],
+			delBand: jest.fn(),
+			addBand: jest.fn(),
+			setData: jest.fn(),
+		};
+		hooks.setSeries(plot, 1, { focus: true });
+
+		expect(plot.setData).not.toHaveBeenCalled();
+	});
+});

frontend/src/container/DashboardContainer/visualization/charts/ChartWrapper/useChartStacking.ts

@@ -0,0 +1,132 @@
+import {
+	MutableRefObject,
+	useCallback,
+	useLayoutEffect,
+	useMemo,
+	useRef,
+} from 'react';
+import { UPlotConfigBuilder } from 'lib/uPlotV2/config/UPlotConfigBuilder';
+import { StackMode } from 'lib/uPlotV2/config/types';
+import { has } from 'lodash-es';
+import uPlot from 'uplot';
+
+import { stackSeries } from '../utils/stackSeriesUtils';
+
+/** Returns true if the series at the given index is hidden (e.g. via legend toggle). */
+function isSeriesHidden(plot: uPlot, seriesIndex: number): boolean {
+	return !plot.series[seriesIndex]?.show;
+}
+
+function canApplyStacking(
+	unstackedData: uPlot.AlignedData | null,
+	plot: uPlot,
+	isUpdating: boolean,
+): boolean {
+	return (
+		!isUpdating &&
+		!!unstackedData &&
+		!!plot.data &&
+		unstackedData[0]?.length === plot.data[0]?.length
+	);
+}
+
+function setupStackingHooks(
+	config: UPlotConfigBuilder,
+	updateStacksInChart: (plot: uPlot) => void,
+	isUpdatingRef: MutableRefObject<boolean>,
+): () => void {
+	const onDataChange = (plot: uPlot): void => {
+		if (!isUpdatingRef.current) {
+			updateStacksInChart(plot);
+		}
+	};
+
+	const onSeriesVisibilityChange = (
+		plot: uPlot,
+		_seriesIdx: number | null,
+		opts: uPlot.Series,
+	): void => {
+		// uPlot fires setSeries for hover focus too; only visibility changes restack.
+		if (!has(opts, 'focus')) {
+			updateStacksInChart(plot);
+		}
+	};
+
+	const removeSetDataHook = config.addHook('setData', onDataChange);
+	const removeSetSeriesHook = config.addHook(
+		'setSeries',
+		onSeriesVisibilityChange,
+	);
+
+	return (): void => {
+		removeSetDataHook?.();
+		removeSetSeriesHook?.();
+	};
+}
+
+export interface UseChartStackingParams {
+	data: uPlot.AlignedData;
+	config: UPlotConfigBuilder | null;
+}
+
+/**
+ * Stacks a chart's data for the mode declared on its config, and re-stacks on data or
+ * visibility changes. The pre-stack values live in a ref because the uPlot hooks that
+ * read them run outside React's render cycle.
+ */
+export function useChartStacking({
+	data,
+	config,
+}: UseChartStackingParams): uPlot.AlignedData {
+	const stack = config?.getStackMode() ?? StackMode.None;
+	const unstackedDataRef = useRef<uPlot.AlignedData | null>(null);
+	unstackedDataRef.current = stack === 'none' ? null : data;
+
+	// Guards the re-entrant setData below, which would otherwise re-trigger our own hook.
+	const isUpdatingChartRef = useRef(false);
+
+	const chartData = useMemo((): uPlot.AlignedData => {
+		if (stack === StackMode.None || !data || data.length < 2) {
+			return data;
+		}
+		const noSeriesHidden = (): boolean => false; // include all series in initial stack
+		return stackSeries(data, noSeriesHidden, stack).data;
+	}, [data, stack]);
+
+	const updateStacksInChart = useCallback(
+		(plot: uPlot): void => {
+			const unstacked = unstackedDataRef.current;
+			if (
+				!unstacked ||
+				!canApplyStacking(unstacked, plot, isUpdatingChartRef.current)
+			) {
+				return;
+			}
+
+			const shouldExcludeSeries = (idx: number): boolean =>
+				isSeriesHidden(plot, idx);
+			const { data: stacked, bands } = stackSeries(
+				unstacked,
+				shouldExcludeSeries,
+				stack,
+			);
+
+			plot.delBand(null);
+			bands.forEach((band: uPlot.Band) => plot.addBand(band));
+
+			isUpdatingChartRef.current = true;
+			plot.setData(stacked);
+			isUpdatingChartRef.current = false;
+		},
+		[stack],
+	);
+
+	useLayoutEffect(() => {
+		if (stack === StackMode.None || !config) {
+			return undefined;
+		}
+		return setupStackingHooks(config, updateStacksInChart, isUpdatingChartRef);
+	}, [stack, config, updateStacksInChart]);
+
+	return chartData;
+}

frontend/src/container/DashboardContainer/visualization/charts/TimeSeries/TimeSeries.tsx

@@ -6,10 +6,16 @@ import {
 	TooltipRenderArgs,
 } from 'lib/uPlotV2/components/types';
 
+import { StackMode } from 'lib/uPlotV2/config/types';
+
 import { TimeSeriesChartProps } from '../types';
 
 export default function TimeSeries(props: TimeSeriesChartProps): JSX.Element {
-	const { children, customTooltip, ...rest } = props;
+	const { children, customTooltip, stack = StackMode.None, ...rest } = props;
+
+	// Written during render so it lands before UPlotChart's effect reads the config,
+	// which derives the fill bands, percent axis unit and percent range from it.
+	rest.config.setStackMode(stack);
 
 	const renderTooltip = useCallback(
 		(props: TooltipRenderArgs): React.ReactNode => {

frontend/src/container/DashboardContainer/visualization/charts/types.ts

@@ -14,6 +14,7 @@ import {
 	ChartClickData,
 } from 'lib/uPlotV2/plugins/TooltipPlugin/types';
 import { BaseAutocompleteData } from 'types/api/queryBuilder/queryAutocompleteResponse';
+import type { StackMode } from 'lib/uPlotV2/config/types';
 
 interface BaseChartProps {
 	width: number;
@@ -52,27 +53,26 @@ interface UPlotChartDataProps {
 	groupByPerQuery?: Record<string, BaseAutocompleteData[]>;
 }
 
-export interface TimeSeriesChartProps
-	extends BaseChartProps, UPlotBasedChartProps, UPlotChartDataProps {
+/** Everything the shared uPlot shell consumes; each chart's props narrow it. */
+export interface ChartWrapperProps
+	extends BaseChartProps, UPlotBasedChartProps, UPlotChartDataProps {}
+
+export interface TimeSeriesChartProps extends ChartWrapperProps {
 	timezone?: Timezone;
+	/** How series compose. Defaults to `none`, which draws them independently. */
+	stack?: StackMode;
 }
 
-export interface HistogramChartProps
-	extends BaseChartProps, UPlotBasedChartProps, UPlotChartDataProps {
+export interface BarChartProps extends ChartWrapperProps {
+	timezone?: Timezone;
+	/** How series compose. Defaults to `none`, which draws them independently. */
+	stack?: StackMode;
+}
+
+export interface HistogramChartProps extends ChartWrapperProps {
 	isQueriesMerged?: boolean;
 }
 
-export interface BarChartProps
-	extends BaseChartProps, UPlotBasedChartProps, UPlotChartDataProps {
-	isStackedBarChart?: boolean;
-	timezone?: Timezone;
-}
-
-export type ChartProps =
-	| TimeSeriesChartProps
-	| BarChartProps
-	| HistogramChartProps;
-
 /**
  * One resolved pie/donut slice: a display label, its (already parsed) positive
  * numeric value, and the colour used for the arc + legend swatch.

frontend/src/container/DashboardContainer/visualization/charts/utils/__tests__/stackSeriesUtils.test.ts

@@ -0,0 +1,158 @@
+import { AlignedData } from 'uplot';
+
+import { StackMode } from 'lib/uPlotV2/config/types';
+
+import { stackSeries } from '../stackSeriesUtils';
+
+const includeAll = (): boolean => false;
+
+// Stacking is top-down: the first series carries the column total, the last its own
+// raw value. Every expectation below reads in that order.
+describe('stackSeries', () => {
+	it('is a no-op under `none`, returning the data and no bands', () => {
+		const data: AlignedData = [[1], [30], [10]];
+
+		const { data: result, bands } = stackSeries(data, includeAll, StackMode.None);
+
+		expect(result).toBe(data);
+		expect(bands).toStrictEqual([]);
+	});
+
+	describe('normal', () => {
+		it('accumulates raw values from the bottom series upward', () => {
+			const data: AlignedData = [
+				[1, 2],
+				[10, 20],
+				[1, 2],
+			];
+
+			expect(stackSeries(data, includeAll, StackMode.Normal).data).toStrictEqual([
+				[1, 2],
+				[11, 22],
+				[1, 2],
+			]);
+		});
+
+		it('treats nulls as 0 without breaking the running total', () => {
+			const data: AlignedData = [
+				[1, 2],
+				[10, null],
+				[1, 2],
+			];
+
+			expect(stackSeries(data, includeAll, StackMode.Normal).data).toStrictEqual([
+				[1, 2],
+				[11, 2],
+				[1, 2],
+			]);
+		});
+
+		it('emits one band per adjacent pair of participating series', () => {
+			const data: AlignedData = [[1], [10], [5], [1]];
+
+			expect(stackSeries(data, includeAll, StackMode.Normal).bands).toStrictEqual([
+				{ series: [1, 2] },
+				{ series: [2, 3] },
+			]);
+		});
+
+		it('copies omitted series through unstacked and skips their bands', () => {
+			const data: AlignedData = [[1], [10], [5], [1]];
+			const omitMiddle = (seriesIndex: number): boolean => seriesIndex === 2;
+
+			const { data: stacked, bands } = stackSeries(
+				data,
+				omitMiddle,
+				StackMode.Normal,
+			);
+
+			expect(stacked).toStrictEqual([[1], [11], [5], [1]]);
+			expect(bands).toStrictEqual([{ series: [1, 3] }]);
+		});
+	});
+
+	describe('percent', () => {
+		it('rescales each column to its total so the top series reads 100', () => {
+			const data: AlignedData = [
+				[1, 2],
+				[30, 10],
+				[10, 10],
+			];
+
+			expect(stackSeries(data, includeAll, StackMode.Percent).data).toStrictEqual([
+				[1, 2],
+				[100, 100],
+				[25, 50],
+			]);
+		});
+
+		it('normalises per column, so an identical series differs across x', () => {
+			const data: AlignedData = [
+				[1, 2],
+				[1, 3],
+				[1, 1],
+			];
+
+			expect(stackSeries(data, includeAll, StackMode.Percent).data).toStrictEqual([
+				[1, 2],
+				[100, 100],
+				[50, 25],
+			]);
+		});
+
+		it('excludes omitted series from the total, so the visible ones still reach 100', () => {
+			const data: AlignedData = [[1], [30], [10], [60]];
+			const omitLast = (seriesIndex: number): boolean => seriesIndex === 3;
+
+			expect(stackSeries(data, omitLast, StackMode.Percent).data).toStrictEqual([
+				[1],
+				[100],
+				[25],
+				[60],
+			]);
+		});
+
+		it('yields 0 for a column whose participating series sum to zero', () => {
+			const data: AlignedData = [
+				[1, 2],
+				[0, 5],
+				[0, 5],
+			];
+
+			expect(stackSeries(data, includeAll, StackMode.Percent).data).toStrictEqual([
+				[1, 2],
+				[0, 100],
+				[0, 50],
+			]);
+		});
+
+		it('divides by the signed total when a column mixes signs', () => {
+			// 30 + (-10) = 20, so the shares are 150% and -50% and still sum to 100.
+			const data: AlignedData = [[1], [30], [-10]];
+
+			expect(stackSeries(data, includeAll, StackMode.Percent).data).toStrictEqual([
+				[1],
+				[100],
+				[-50],
+			]);
+		});
+
+		it('yields 0 across a column whose signed total cancels to zero', () => {
+			const data: AlignedData = [[1], [10], [-10]];
+
+			expect(stackSeries(data, includeAll, StackMode.Percent).data).toStrictEqual([
+				[1],
+				[0],
+				[0],
+			]);
+		});
+	});
+
+	it('defaults to normal when no mode is given', () => {
+		const data: AlignedData = [[1], [30], [10]];
+
+		expect(stackSeries(data, includeAll).data).toStrictEqual(
+			stackSeries(data, includeAll, StackMode.Normal).data,
+		);
+	});
+});

frontend/src/container/DashboardContainer/visualization/charts/utils/__tests__/stackUtils.test.ts

@@ -1,117 +0,0 @@
-import { AlignedData } from 'uplot';
-
-import { getInitialStackedBands, stack } from '../stackUtils';
-
-describe('stackUtils', () => {
-	describe('stack', () => {
-		const neverOmit = (): boolean => false;
-
-		it('preserves time axis as first row', () => {
-			const data: AlignedData = [
-				[100, 200, 300],
-				[1, 2, 3],
-				[4, 5, 6],
-			];
-			const { data: result } = stack(data, neverOmit);
-			expect(result[0]).toStrictEqual([100, 200, 300]);
-		});
-
-		it('stacks value series cumulatively (last = raw, first = total)', () => {
-			// Time, then 3 value series. Stack order: last series stays raw, then we add upward.
-			const data: AlignedData = [
-				[0, 1, 2],
-				[1, 2, 3], // series 1
-				[4, 5, 6], // series 2
-				[7, 8, 9], // series 3
-			];
-			const { data: result } = stack(data, neverOmit);
-			// result[1] = s1+s2+s3, result[2] = s2+s3, result[3] = s3
-			expect(result[1]).toStrictEqual([12, 15, 18]); // 1+4+7, 2+5+8, 3+6+9
-			expect(result[2]).toStrictEqual([11, 13, 15]); // 4+7, 5+8, 6+9
-			expect(result[3]).toStrictEqual([7, 8, 9]);
-		});
-
-		it('treats null values as 0 when stacking', () => {
-			const data: AlignedData = [
-				[0, 1],
-				[1, null],
-				[null, 10],
-			];
-			const { data: result } = stack(data, neverOmit);
-			expect(result[1]).toStrictEqual([1, 10]); // total
-			expect(result[2]).toStrictEqual([0, 10]); // last series with null→0
-		});
-
-		it('copies omitted series as-is without accumulating', () => {
-			// Omit series 2 (index 2); series 1 and 3 are stacked.
-			const data: AlignedData = [
-				[0, 1],
-				[10, 20], // series 1
-				[100, 200], // series 2 - omitted
-				[1, 2], // series 3
-			];
-			const omitSeries2 = (i: number): boolean => i === 2;
-			const { data: result } = stack(data, omitSeries2);
-			// series 3 raw: [1, 2]; series 2 omitted: [100, 200] as-is; series 1 stacked with s3: [11, 22]
-			expect(result[1]).toStrictEqual([11, 22]); // 10+1, 20+2
-			expect(result[2]).toStrictEqual([100, 200]); // copied, not stacked
-			expect(result[3]).toStrictEqual([1, 2]);
-		});
-
-		it('returns bands between consecutive visible series when none omitted', () => {
-			const data: AlignedData = [
-				[0, 1],
-				[1, 2],
-				[3, 4],
-				[5, 6],
-			];
-			const { bands } = stack(data, neverOmit);
-			expect(bands).toStrictEqual([{ series: [1, 2] }, { series: [2, 3] }]);
-		});
-
-		it('returns bands only between visible series when some are omitted', () => {
-			// 4 value series; omit index 2. Visible: 1, 3, 4. Bands: [1,3], [3,4]
-			const data: AlignedData = [[0], [1], [2], [3], [4]];
-			const omitSeries2 = (i: number): boolean => i === 2;
-			const { bands } = stack(data, omitSeries2);
-			expect(bands).toStrictEqual([{ series: [1, 3] }, { series: [3, 4] }]);
-		});
-
-		it('returns empty bands when only one value series', () => {
-			const data: AlignedData = [
-				[0, 1],
-				[1, 2],
-			];
-			const { bands } = stack(data, neverOmit);
-			expect(bands).toStrictEqual([]);
-		});
-	});
-
-	describe('getInitialStackedBands', () => {
-		it('returns one band between each consecutive pair for seriesCount 3', () => {
-			expect(getInitialStackedBands(3)).toStrictEqual([
-				{ series: [1, 2] },
-				{ series: [2, 3] },
-			]);
-		});
-
-		it('returns empty array for seriesCount 0 or 1', () => {
-			expect(getInitialStackedBands(0)).toStrictEqual([]);
-			expect(getInitialStackedBands(1)).toStrictEqual([]);
-		});
-
-		it('returns single band for seriesCount 2', () => {
-			expect(getInitialStackedBands(2)).toStrictEqual([{ series: [1, 2] }]);
-		});
-
-		it('returns bands [1,2], [2,3], ..., [n-1, n] for seriesCount n', () => {
-			const bands = getInitialStackedBands(5);
-			expect(bands).toStrictEqual([
-				{ series: [1, 2] },
-				{ series: [2, 3] },
-				{ series: [3, 4] },
-				{ series: [4, 5] },
-			]);
-		});
-	});
-});

frontend/src/container/DashboardContainer/visualization/charts/utils/stackSeriesUtils.ts

@@ -1,13 +1,20 @@
+import { StackMode } from 'lib/uPlotV2/config/types';
 import uPlot, { AlignedData } from 'uplot';
 
 /**
  * Stack data cumulatively (top-down: first series = top, last = bottom).
- * When `omit(seriesIndex)` returns true, that series is excluded from stacking.
+ * When `omit(seriesIndex)` returns true, that series keeps its raw values and
+ * contributes nothing to the total. `None` is a no-op.
  */
 export function stackSeries(
 	data: AlignedData,
 	omit: (seriesIndex: number) => boolean,
+	mode: StackMode = StackMode.Normal,
 ): { data: AlignedData; bands: uPlot.Band[] } {
+	if (mode === StackMode.None) {
+		return { data, bands: [] };
+	}
+
 	const timeAxis = data[0];
 	const pointCount = timeAxis.length;
 	const valueSeriesCount = data.length - 1; // exclude time axis
@@ -17,6 +24,7 @@ export function stackSeries(
 		valueSeriesCount,
 		pointCount,
 		omit,
+		mode,
 	});
 	const bands = buildFillBands(valueSeriesCount + 1, omit); // +1 for 1-based series indices
 
@@ -31,6 +39,46 @@ interface BuildStackedSeriesParams {
 	valueSeriesCount: number;
 	pointCount: number;
 	omit: (seriesIndex: number) => boolean;
+	mode: StackMode;
+}
+
+/** Per-point total. Mixed-sign columns sum signed, as "share of total" implies. */
+function columnTotals({
+	data,
+	valueSeriesCount,
+	pointCount,
+	omit,
+}: Omit<BuildStackedSeriesParams, 'mode'>): number[] {
+	const totals = Array(pointCount).fill(0) as number[];
+
+	for (let seriesIndex = 1; seriesIndex <= valueSeriesCount; seriesIndex++) {
+		if (omit(seriesIndex)) {
+			continue;
+		}
+		const rawValues = data[seriesIndex] as (number | null)[];
+		rawValues.forEach((rawValue, pointIndex) => {
+			totals[pointIndex] += rawValue == null ? 0 : Number(rawValue);
+		});
+	}
+
+	return totals;
+}
+
+/** A column whose participating series sum to 0 has no share to divide, so every slice is 0. */
+function toPercent(value: number, total: number): number {
+	return total === 0 ? 0 : (value / total) * 100;
+}
+
+/** What a raw value adds to the stack at a given point. */
+type Contribution = (value: number, pointIndex: number) => number;
+
+function contributionForMode(params: BuildStackedSeriesParams): Contribution {
+	if (params.mode !== StackMode.Percent) {
+		return (value): number => value;
+	}
+	// Resolved up front: totals span series the accumulation below has not reached yet.
+	const totals = columnTotals(params);
+	return (value, pointIndex): number => toPercent(value, totals[pointIndex]);
 }
 
 /**
@@ -42,9 +90,17 @@ function buildStackedSeries({
 	valueSeriesCount,
 	pointCount,
 	omit,
+	mode,
 }: BuildStackedSeriesParams): (number | null)[][] {
 	const stackedSeries: (number | null)[][] = Array(valueSeriesCount);
 	const cumulativeSums = Array(pointCount).fill(0) as number[];
+	const contributionOf = contributionForMode({
+		data,
+		valueSeriesCount,
+		pointCount,
+		omit,
+		mode,
+	});
 
 	for (let seriesIndex = valueSeriesCount; seriesIndex >= 1; seriesIndex--) {
 		const rawValues = data[seriesIndex] as (number | null)[];
@@ -54,7 +110,10 @@ function buildStackedSeries({
 		} else {
 			stackedSeries[seriesIndex - 1] = rawValues.map((rawValue, pointIndex) => {
 				const numericValue = rawValue == null ? 0 : Number(rawValue);
-				return (cumulativeSums[pointIndex] += numericValue);
+				return (cumulativeSums[pointIndex] += contributionOf(
+					numericValue,
+					pointIndex,
+				));
 			});
 		}
 	}
@@ -101,16 +160,3 @@ function findNextVisibleSeriesIndex(
 	}
 	return -1;
 }
-
-/**
- * Returns band indices for initial stacked state (no series omitted).
- * Top-down: first series at top, band fills between consecutive series.
- * uPlot band format: [upperSeriesIdx, lowerSeriesIdx].
- */
-export function getInitialStackedBands(seriesCount: number): uPlot.Band[] {
-	const bands: uPlot.Band[] = [];
-	for (let seriesIndex = 1; seriesIndex < seriesCount; seriesIndex++) {
-		bands.push({ series: [seriesIndex, seriesIndex + 1] });
-	}
-	return bands;
-}

frontend/src/container/DashboardContainer/visualization/charts/utils/stackUtils.ts

@@ -1,116 +0,0 @@
-import uPlot, { AlignedData } from 'uplot';
-
-/**
- * Stack data cumulatively (top-down: first series = top, last = bottom).
- * When `omit(seriesIndex)` returns true, that series is excluded from stacking.
- */
-export function stack(
-	data: AlignedData,
-	omit: (seriesIndex: number) => boolean,
-): { data: AlignedData; bands: uPlot.Band[] } {
-	const timeAxis = data[0];
-	const pointCount = timeAxis.length;
-	const valueSeriesCount = data.length - 1; // exclude time axis
-
-	const stackedSeries = buildStackedSeries({
-		data,
-		valueSeriesCount,
-		pointCount,
-		omit,
-	});
-	const bands = buildFillBands(valueSeriesCount + 1, omit); // +1 for 1-based series indices
-
-	return {
-		data: [timeAxis, ...stackedSeries] as AlignedData,
-		bands,
-	};
-}
-
-interface BuildStackedSeriesParams {
-	data: AlignedData;
-	valueSeriesCount: number;
-	pointCount: number;
-	omit: (seriesIndex: number) => boolean;
-}
-
-/**
- * Accumulate from last series upward: last series = raw values, first = total.
- * Omitted series are copied as-is (no accumulation).
- */
-function buildStackedSeries({
-	data,
-	valueSeriesCount,
-	pointCount,
-	omit,
-}: BuildStackedSeriesParams): (number | null)[][] {
-	const stackedSeries: (number | null)[][] = Array(valueSeriesCount);
-	const cumulativeSums = Array(pointCount).fill(0) as number[];
-
-	for (let seriesIndex = valueSeriesCount; seriesIndex >= 1; seriesIndex--) {
-		const rawValues = data[seriesIndex] as (number | null)[];
-
-		if (omit(seriesIndex)) {
-			stackedSeries[seriesIndex - 1] = rawValues;
-		} else {
-			stackedSeries[seriesIndex - 1] = rawValues.map((rawValue, pointIndex) => {
-				const numericValue = rawValue == null ? 0 : Number(rawValue);
-				return (cumulativeSums[pointIndex] += numericValue);
-			});
-		}
-	}
-
-	return stackedSeries;
-}
-
-/**
- * Bands define fill between consecutive visible series for stacked appearance.
- * uPlot format: [upperSeriesIdx, lowerSeriesIdx].
- */
-function buildFillBands(
-	seriesLength: number,
-	omit: (seriesIndex: number) => boolean,
-): uPlot.Band[] {
-	const bands: uPlot.Band[] = [];
-
-	for (let seriesIndex = 1; seriesIndex < seriesLength; seriesIndex++) {
-		if (omit(seriesIndex)) {
-			continue;
-		}
-		const nextVisibleSeriesIndex = findNextVisibleSeriesIndex(
-			seriesLength,
-			seriesIndex,
-			omit,
-		);
-		if (nextVisibleSeriesIndex !== -1) {
-			bands.push({ series: [seriesIndex, nextVisibleSeriesIndex] });
-		}
-	}
-
-	return bands;
-}
-
-function findNextVisibleSeriesIndex(
-	seriesLength: number,
-	afterIndex: number,
-	omit: (seriesIndex: number) => boolean,
-): number {
-	for (let i = afterIndex + 1; i < seriesLength; i++) {
-		if (!omit(i)) {
-			return i;
-		}
-	}
-	return -1;
-}
-
-/**
- * Returns band indices for initial stacked state (no series omitted).
- * Top-down: first series at top, band fills between consecutive series.
- * uPlot band format: [upperSeriesIdx, lowerSeriesIdx].
- */
-export function getInitialStackedBands(seriesCount: number): uPlot.Band[] {
-	const bands: uPlot.Band[] = [];
-	for (let seriesIndex = 1; seriesIndex < seriesCount; seriesIndex++) {
-		bands.push({ series: [seriesIndex, seriesIndex + 1] });
-	}
-	return bands;
-}

frontend/src/container/DashboardContainer/visualization/hooks/__tests__/useBarChartStacking.test.ts

@@ -1,313 +0,0 @@
-import { renderHook } from '@testing-library/react';
-import uPlot from 'uplot';
-
-import type { UseBarChartStackingParams } from '../useBarChartStacking';
-import { useBarChartStacking } from '../useBarChartStacking';
-
-type MockConfig = { addHook: jest.Mock };
-
-function asConfig(c: MockConfig): UseBarChartStackingParams['config'] {
-	return c as unknown as UseBarChartStackingParams['config'];
-}
-
-function createMockConfig(): {
-	config: MockConfig;
-	invokeSetData: (plot: uPlot) => void;
-	invokeSetSeries: (
-		plot: uPlot,
-		seriesIndex: number | null,
-		opts: Partial<uPlot.Series> & { focus?: boolean },
-	) => void;
-	removeSetData: jest.Mock;
-	removeSetSeries: jest.Mock;
-} {
-	let setDataHandler: ((plot: uPlot) => void) | null = null;
-	let setSeriesHandler:
-		| ((plot: uPlot, seriesIndex: number | null, opts: uPlot.Series) => void)
-		| null = null;
-
-	const removeSetData = jest.fn();
-	const removeSetSeries = jest.fn();
-
-	const addHook = jest.fn(
-		(
-			hookName: string,
-			handler: (plot: uPlot, ...args: unknown[]) => void,
-		): (() => void) => {
-			if (hookName === 'setData') {
-				setDataHandler = handler as (plot: uPlot) => void;
-				return removeSetData;
-			}
-			if (hookName === 'setSeries') {
-				setSeriesHandler = handler as (
-					plot: uPlot,
-					seriesIndex: number | null,
-					opts: uPlot.Series,
-				) => void;
-				return removeSetSeries;
-			}
-			return jest.fn();
-		},
-	);
-
-	const config: MockConfig = { addHook };
-
-	const invokeSetData = (plot: uPlot): void => {
-		setDataHandler?.(plot);
-	};
-
-	const invokeSetSeries = (
-		plot: uPlot,
-		seriesIndex: number | null,
-		opts: Partial<uPlot.Series> & { focus?: boolean },
-	): void => {
-		setSeriesHandler?.(plot, seriesIndex, opts as uPlot.Series);
-	};
-
-	return {
-		config,
-		invokeSetData,
-		invokeSetSeries,
-		removeSetData,
-		removeSetSeries,
-	};
-}
-
-function createMockPlot(overrides: Partial<uPlot> = {}): uPlot {
-	return {
-		data: [
-			[0, 1, 2],
-			[1, 2, 3],
-			[4, 5, 6],
-		],
-		series: [{ show: true }, { show: true }, { show: true }],
-		delBand: jest.fn(),
-		addBand: jest.fn(),
-		setData: jest.fn(),
-		...overrides,
-	} as unknown as uPlot;
-}
-
-describe('useBarChartStacking', () => {
-	it('returns data as-is when isStackedBarChart is false', () => {
-		const data: uPlot.AlignedData = [
-			[100, 200],
-			[1, 2],
-			[3, 4],
-		];
-		const { result } = renderHook(() =>
-			useBarChartStacking({
-				data,
-				isStackedBarChart: false,
-				config: null,
-			}),
-		);
-		expect(result.current).toBe(data);
-	});
-
-	it('returns data as-is when config is null and isStackedBarChart is true', () => {
-		const data: uPlot.AlignedData = [
-			[0, 1],
-			[1, 2],
-			[4, 5],
-		];
-		const { result } = renderHook(() =>
-			useBarChartStacking({
-				data,
-				isStackedBarChart: true,
-				config: null,
-			}),
-		);
-		// Still returns stacked data (computed in useMemo); no hooks registered
-		expect(result.current[0]).toStrictEqual([0, 1]);
-		expect(result.current[1]).toStrictEqual([5, 7]); // stacked
-		expect(result.current[2]).toStrictEqual([4, 5]);
-	});
-
-	it('returns stacked data when isStackedBarChart is true and multiple value series', () => {
-		const data: uPlot.AlignedData = [
-			[0, 1, 2],
-			[1, 2, 3],
-			[4, 5, 6],
-			[7, 8, 9],
-		];
-		const { result } = renderHook(() =>
-			useBarChartStacking({
-				data,
-				isStackedBarChart: true,
-				config: null,
-			}),
-		);
-		expect(result.current[0]).toStrictEqual([0, 1, 2]);
-		expect(result.current[1]).toStrictEqual([12, 15, 18]); // s1+s2+s3
-		expect(result.current[2]).toStrictEqual([11, 13, 15]); // s2+s3
-		expect(result.current[3]).toStrictEqual([7, 8, 9]);
-	});
-
-	it('returns data as-is when only one value series (no stacking needed)', () => {
-		const data: uPlot.AlignedData = [
-			[0, 1],
-			[1, 2],
-		];
-		const { result } = renderHook(() =>
-			useBarChartStacking({
-				data,
-				isStackedBarChart: true,
-				config: null,
-			}),
-		);
-		expect(result.current).toStrictEqual(data);
-	});
-
-	it('registers setData and setSeries hooks when isStackedBarChart and config provided', () => {
-		const { config } = createMockConfig();
-		const data: uPlot.AlignedData = [
-			[0, 1],
-			[1, 2],
-			[3, 4],
-		];
-
-		renderHook(() =>
-			useBarChartStacking({
-				data,
-				isStackedBarChart: true,
-				config: asConfig(config),
-			}),
-		);
-
-		expect(config.addHook).toHaveBeenCalledWith('setData', expect.any(Function));
-		expect(config.addHook).toHaveBeenCalledWith(
-			'setSeries',
-			expect.any(Function),
-		);
-	});
-
-	it('does not register hooks when isStackedBarChart is false', () => {
-		const { config } = createMockConfig();
-		const data: uPlot.AlignedData = [
-			[0, 1],
-			[1, 2],
-			[3, 4],
-		];
-
-		renderHook(() =>
-			useBarChartStacking({
-				data,
-				isStackedBarChart: false,
-				config: asConfig(config),
-			}),
-		);
-
-		expect(config.addHook).not.toHaveBeenCalled();
-	});
-
-	it('calls cleanup when unmounted', () => {
-		const { config, removeSetData, removeSetSeries } = createMockConfig();
-		const data: uPlot.AlignedData = [
-			[0, 1],
-			[1, 2],
-			[3, 4],
-		];
-
-		const { unmount } = renderHook(() =>
-			useBarChartStacking({
-				data,
-				isStackedBarChart: true,
-				config: asConfig(config),
-			}),
-		);
-
-		unmount();
-
-		expect(removeSetData).toHaveBeenCalled();
-		expect(removeSetSeries).toHaveBeenCalled();
-	});
-
-	it('re-stacks and updates plot when setData hook is invoked', () => {
-		const { config, invokeSetData } = createMockConfig();
-		const data: uPlot.AlignedData = [
-			[0, 1, 2],
-			[1, 2, 3],
-			[4, 5, 6],
-		];
-		const plot = createMockPlot({
-			data: [
-				[0, 1, 2],
-				[5, 7, 9],
-				[4, 5, 6],
-			],
-		});
-
-		renderHook(() =>
-			useBarChartStacking({
-				data,
-				isStackedBarChart: true,
-				config: asConfig(config),
-			}),
-		);
-
-		invokeSetData(plot);
-
-		expect(plot.delBand).toHaveBeenCalledWith(null);
-		expect(plot.addBand).toHaveBeenCalled();
-		expect(plot.setData).toHaveBeenCalledWith(
-			expect.arrayContaining([
-				[0, 1, 2],
-				expect.any(Array), // stacked row 1
-				expect.any(Array), // stacked row 2
-			]),
-		);
-	});
-
-	it('re-stacks when setSeries hook is invoked (e.g. legend toggle)', () => {
-		const { config, invokeSetSeries } = createMockConfig();
-		const data: uPlot.AlignedData = [
-			[0, 1],
-			[10, 20],
-			[5, 10],
-		];
-		// Plot data must match unstacked length so canApplyStacking passes
-		const plot = createMockPlot({
-			data: [
-				[0, 1],
-				[15, 30],
-				[5, 10],
-			],
-		});
-
-		renderHook(() =>
-			useBarChartStacking({
-				data,
-				isStackedBarChart: true,
-				config: asConfig(config),
-			}),
-		);
-
-		invokeSetSeries(plot, 1, { show: false });
-
-		expect(plot.setData).toHaveBeenCalled();
-	});
-
-	it('does not re-stack when setSeries is called with focus option', () => {
-		const { config, invokeSetSeries } = createMockConfig();
-		const data: uPlot.AlignedData = [
-			[0, 1],
-			[1, 2],
-			[3, 4],
-		];
-		const plot = createMockPlot();
-
-		renderHook(() =>
-			useBarChartStacking({
-				data,
-				isStackedBarChart: true,
-				config: asConfig(config),
-			}),
-		);
-
-		(plot.setData as jest.Mock).mockClear();
-		invokeSetSeries(plot, 1, { focus: true } as uPlot.Series);
-
-		expect(plot.setData).not.toHaveBeenCalled();
-	});
-});

frontend/src/container/DashboardContainer/visualization/hooks/useBarChartStacking.ts

@@ -1,125 +0,0 @@
-import {
-	MutableRefObject,
-	useCallback,
-	useLayoutEffect,
-	useMemo,
-	useRef,
-} from 'react';
-import { UPlotConfigBuilder } from 'lib/uPlotV2/config/UPlotConfigBuilder';
-import { has } from 'lodash-es';
-import uPlot from 'uplot';
-
-import { stackSeries } from '../charts/utils/stackSeriesUtils';
-
-/** Returns true if the series at the given index is hidden (e.g. via legend toggle). */
-function isSeriesHidden(plot: uPlot, seriesIndex: number): boolean {
-	return !plot.series[seriesIndex]?.show;
-}
-
-function canApplyStacking(
-	unstackedData: uPlot.AlignedData | null,
-	plot: uPlot,
-	isUpdating: boolean,
-): boolean {
-	return (
-		!isUpdating &&
-		!!unstackedData &&
-		!!plot.data &&
-		unstackedData[0]?.length === plot.data[0]?.length
-	);
-}
-
-function setupStackingHooks(
-	config: UPlotConfigBuilder,
-	applyStackingToChart: (plot: uPlot) => void,
-	isUpdatingRef: MutableRefObject<boolean>,
-): () => void {
-	const onDataChange = (plot: uPlot): void => {
-		if (!isUpdatingRef.current) {
-			applyStackingToChart(plot);
-		}
-	};
-
-	const onSeriesVisibilityChange = (
-		plot: uPlot,
-		_seriesIdx: number | null,
-		opts: uPlot.Series,
-	): void => {
-		if (!has(opts, 'focus')) {
-			applyStackingToChart(plot);
-		}
-	};
-
-	const removeSetDataHook = config.addHook('setData', onDataChange);
-	const removeSetSeriesHook = config.addHook(
-		'setSeries',
-		onSeriesVisibilityChange,
-	);
-
-	return (): void => {
-		removeSetDataHook?.();
-		removeSetSeriesHook?.();
-	};
-}
-
-export interface UseBarChartStackingParams {
-	data: uPlot.AlignedData;
-	isStackedBarChart?: boolean;
-	config: UPlotConfigBuilder | null;
-}
-
-/**
- * Handles stacking for bar charts: computes initial stacked data and re-stacks
- * when data or series visibility changes (e.g. legend toggles).
- */
-export function useBarChartStacking({
-	data,
-	isStackedBarChart = false,
-	config,
-}: UseBarChartStackingParams): uPlot.AlignedData {
-	// Store unstacked source data so uPlot hooks can access it (hooks run outside React's render cycle)
-	const unstackedDataRef = useRef<uPlot.AlignedData | null>(null);
-	unstackedDataRef.current = isStackedBarChart ? data : null;
-
-	// Prevents re-entrant calls when we update chart data (avoids infinite loop in setData hook)
-	const isUpdatingChartRef = useRef(false);
-
-	const chartData = useMemo((): uPlot.AlignedData => {
-		if (!isStackedBarChart || !data || data.length < 2) {
-			return data;
-		}
-		const noSeriesHidden = (): boolean => false; // include all series in initial stack
-		const { data: stacked } = stackSeries(data, noSeriesHidden);
-		return stacked;
-	}, [data, isStackedBarChart]);
-
-	const applyStackingToChart = useCallback((plot: uPlot): void => {
-		const unstacked = unstackedDataRef.current;
-		if (
-			!unstacked ||
-			!canApplyStacking(unstacked, plot, isUpdatingChartRef.current)
-		) {
-			return;
-		}
-
-		const shouldExcludeSeries = (idx: number): boolean =>
-			isSeriesHidden(plot, idx);
-		const { data: stacked, bands } = stackSeries(unstacked, shouldExcludeSeries);
-
-		plot.delBand(null);
-		bands.forEach((band: uPlot.Band) => plot.addBand(band));
-
-		isUpdatingChartRef.current = true;
-		plot.setData(stacked);
-		isUpdatingChartRef.current = false;
-	}, []);
-
-	useLayoutEffect(() => {
-		if (!isStackedBarChart || !config) {
-			return undefined;
-		}
-		return setupStackingHooks(config, applyStackingToChart, isUpdatingChartRef);
-	}, [isStackedBarChart, config, applyStackingToChart]);
-
-	return chartData;
-}

frontend/src/container/DashboardContainer/visualization/panels/BarPanel/BarPanel.tsx

@@ -22,6 +22,7 @@ import { prepareBarPanelConfig } from './utils';
 import '../Panel.styles.scss';
 import TooltipFooter from '../components/TooltipFooter';
 import { prepareChartData } from 'lib/uPlotV2/utils/dataUtils';
+import { StackMode } from 'lib/uPlotV2/config/types';
 
 function BarPanel(props: PanelWrapperProps): JSX.Element {
 	const {
@@ -147,6 +148,7 @@ function BarPanel(props: PanelWrapperProps): JSX.Element {
 			{containerDimensions.width > 0 && containerDimensions.height > 0 && (
 				<BarChart
 					key={`${syncMode}-${syncFilterMode}`}
+					stack={widget.stackedBarChart ? StackMode.Normal : StackMode.None}
 					config={config}
 					legendConfig={{
 						position: widget?.legendPosition ?? LegendPosition.BOTTOM,
@@ -159,7 +161,6 @@ function BarPanel(props: PanelWrapperProps): JSX.Element {
 					height={containerDimensions.height}
 					layoutChildren={layoutChildren}
 					groupByPerQuery={groupByPerQuery}
-					isStackedBarChart={widget.stackedBarChart ?? false}
 					yAxisUnit={widget.yAxisUnit}
 					decimalPrecision={widget.decimalPrecision}
 					timezone={timezone}

frontend/src/container/DashboardContainer/visualization/panels/BarPanel/__tests__/utils.test.ts

@@ -35,20 +35,10 @@ jest.mock('lib/getLabelName', () => ({
 	),
 }));
 
-jest.mock(
-	'container/DashboardContainer/visualization/charts/utils/stackSeriesUtils',
-	() => ({
-		getInitialStackedBands: jest.fn().mockReturnValue([]),
-	}),
-);
-
 const getLegendMock = jest.requireMock('lib/dashboard/getQueryResults')
 	.getLegend as jest.Mock;
 const getLabelNameMock = jest.requireMock('lib/getLabelName')
 	.default as jest.Mock;
-const getInitialStackedBandsMock = jest.requireMock(
-	'container/DashboardContainer/visualization/charts/utils/stackSeriesUtils',
-).getInitialStackedBands as jest.Mock;
 
 const createApiResponse = (
 	result: MetricRangePayloadProps['data']['result'] = [],
@@ -247,36 +237,5 @@ describe('BarPanel utils', () => {
 			}).getConfig();
 			expect(config.series?.[1]).toMatchObject({ stroke: '#ff0000' });
 		});
-
-		it('calls getInitialStackedBands when widget is stackedBarChart', () => {
-			const widget = createWidget({ stackedBarChart: true });
-			const apiResponse = createApiResponse([
-				{
-					metric: {},
-					queryName: 'Q1',
-					values: [[1000, '1']],
-				} as MetricRangePayloadProps['data']['result'][0],
-				{
-					metric: {},
-					queryName: 'Q2',
-					values: [[1000, '2']],
-				} as MetricRangePayloadProps['data']['result'][0],
-			]);
-			prepareBarPanelConfig({ ...baseParams, widget, apiResponse });
-			// seriesCount = result.length + 1 = 3
-			expect(getInitialStackedBandsMock).toHaveBeenCalledWith(3);
-		});
-
-		it('does not call getInitialStackedBands for non-stacked chart', () => {
-			const apiResponse = createApiResponse([
-				{
-					metric: {},
-					queryName: 'Q1',
-					values: [[1000, '1']],
-				} as MetricRangePayloadProps['data']['result'][0],
-			]);
-			prepareBarPanelConfig({ ...baseParams, apiResponse });
-			expect(getInitialStackedBandsMock).not.toHaveBeenCalled();
-		});
 	});
 });

frontend/src/container/DashboardContainer/visualization/panels/BarPanel/utils.ts

@@ -1,7 +1,6 @@
 import { ExecStats } from 'api/v5/v5';
 import { Timezone } from 'components/CustomTimePicker/timezoneUtils';
 import { PANEL_TYPES } from 'constants/queryBuilder';
-import { getInitialStackedBands } from 'container/DashboardContainer/visualization/charts/utils/stackSeriesUtils';
 import { getLegend } from 'lib/dashboard/getQueryResults';
 import getLabelName from 'lib/getLabelName';
 import { OnClickPluginOpts } from 'lib/uPlotLib/plugins/onClickPlugin';
@@ -69,11 +68,6 @@ export function prepareBarPanelConfig({
 		return builder;
 	}
 
-	if (widget.stackedBarChart) {
-		const seriesCount = (apiResponse.data.result.length ?? 0) + 1; // +1 for 1-based uPlot series indices
-		builder.setBands(getInitialStackedBands(seriesCount));
-	}
-
 	apiResponse.data.result.forEach((series) => {
 		const baseLabelName = getLabelName(
 			series.metric,

frontend/src/container/MeterExplorer/Explorer/TimeSeries.tsx

@@ -9,6 +9,7 @@ import { useIsDarkMode } from 'hooks/useDarkMode';
 import { useResizeObserver } from 'hooks/useDimensions';
 import useUrlYAxisUnit from 'hooks/useUrlYAxisUnit';
 import { LegendPosition } from 'lib/uPlotV2/components/types';
+import { StackMode } from 'lib/uPlotV2/config/types';
 import { prepareChartData } from 'lib/uPlotV2/utils/dataUtils';
 import { useTimezone } from 'providers/Timezone';
 import { AppState } from 'store/reducers';
@@ -137,6 +138,7 @@ function TimeSeries({
 									key={`${WIDGET_ID}-${index}`}
 								>
 									<BarChart
+										stack={StackMode.Normal}
 										config={chart.config}
 										legendConfig={{
 											position: LegendPosition.BOTTOM,
@@ -144,7 +146,6 @@ function TimeSeries({
 										data={chart.chartData as uPlot.AlignedData}
 										width={containerDimensions.width}
 										height={containerDimensions.height}
-										isStackedBarChart
 										yAxisUnit={yAxisUnit || 'short'}
 										timezone={timezone}
 									/>

frontend/src/container/MeterExplorer/Explorer/configBuilder.ts

@@ -1,6 +1,5 @@
 import { Timezone } from 'components/CustomTimePicker/timezoneUtils';
 import { PANEL_TYPES } from 'constants/queryBuilder';
-import { getInitialStackedBands } from 'container/DashboardContainer/visualization/charts/utils/stackSeriesUtils';
 import { getLegend } from 'lib/dashboard/getQueryResults';
 import getLabelName from 'lib/getLabelName';
 import {
@@ -89,9 +88,6 @@ export function buildMeterChartConfig({
 		return builder;
 	}
 
-	const seriesCount = (apiResponse.data.result.length ?? 0) + 1;
-	builder.setBands(getInitialStackedBands(seriesCount));
-
 	apiResponse.data.result.forEach((series) => {
 		const baseLabelName = getLabelName(
 			series.metric,

frontend/src/lib/uPlotV2/components/Tooltip/BarChartTooltip.tsx

@@ -9,6 +9,7 @@ export default function BarChartTooltip(props: BarTooltipProps): JSX.Element {
 		(): TooltipContentItem[] =>
 			buildTooltipContent({
 				data: props.uPlotInstance.data,
+				unstackedData: props.unstackedData,
 				series: props.uPlotInstance.series,
 				dataIndexes: props.dataIndexes,
 				activeSeriesIndex: props.seriesIndex,
@@ -21,6 +22,7 @@ export default function BarChartTooltip(props: BarTooltipProps): JSX.Element {
 			}),
 		[
 			props.uPlotInstance,
+			props.unstackedData,
 			props.seriesIndex,
 			props.dataIndexes,
 			props.yAxisUnit,

frontend/src/lib/uPlotV2/components/Tooltip/TimeSeriesTooltip.tsx

@@ -11,6 +11,7 @@ export default function TimeSeriesTooltip(
 		(): TooltipContentItem[] =>
 			buildTooltipContent({
 				data: props.uPlotInstance.data,
+				unstackedData: props.unstackedData,
 				series: props.uPlotInstance.series,
 				dataIndexes: props.dataIndexes,
 				activeSeriesIndex: props.seriesIndex,
@@ -22,6 +23,7 @@ export default function TimeSeriesTooltip(
 			}),
 		[
 			props.uPlotInstance,
+			props.unstackedData,
 			props.seriesIndex,
 			props.dataIndexes,
 			props.yAxisUnit,

frontend/src/lib/uPlotV2/components/Tooltip/__tests__/utils.test.ts

@@ -72,6 +72,35 @@ describe('Tooltip utils', () => {
 			expect(result).toBe(20);
 		});
 
+		it('reports the pre-stack value, identically for normal and percent', () => {
+			const unstackedData: AlignedData = [[0], [30], [10]];
+			const series = [{}, { show: true }, { show: true }] as Series[];
+			const read = (data: AlignedData): number | null =>
+				getTooltipBaseValue({
+					data,
+					unstackedData,
+					index: 1,
+					dataIndex: 0,
+					isStackedBarChart: true,
+					series,
+				});
+
+			expect(read([[0], [40], [10]])).toBe(30);
+			expect(read([[0], [100], [25]])).toBe(30);
+		});
+
+		it('falls back to subtraction when no pre-stack data is given', () => {
+			const result = getTooltipBaseValue({
+				data: [[0], [40], [10]],
+				index: 1,
+				dataIndex: 0,
+				isStackedBarChart: true,
+				series: [{}, { show: true }, { show: true }] as Series[],
+			});
+
+			expect(result).toBe(30);
+		});
+
 		it('returns null when value is missing', () => {
 			const data: AlignedData = [
 				[0, 1],

frontend/src/lib/uPlotV2/components/Tooltip/utils.ts

@@ -23,17 +23,25 @@ export function resolveSeriesColor(
 
 export function getTooltipBaseValue({
 	data,
+	unstackedData,
 	index,
 	dataIndex,
 	isStackedBarChart,
 	series,
 }: {
 	data: AlignedData;
+	unstackedData?: AlignedData;
 	index: number;
 	dataIndex: number;
 	isStackedBarChart?: boolean;
 	series?: Series[];
 }): number | null {
+	// The subtraction below only recovers the raw value under `normal` stacking.
+	const unstackedSeries = unstackedData?.[index];
+	if (unstackedSeries) {
+		return unstackedSeries[dataIndex] ?? null;
+	}
+
 	let baseValue = data[index][dataIndex] ?? null;
 	// Top-down stacking (first series at top): raw = stacked[i] - stacked[nextVisible].
 	// When series are hidden, we must use the next *visible* series, not index+1,
@@ -56,6 +64,7 @@ export function getTooltipBaseValue({
 
 export function buildTooltipContent({
 	data,
+	unstackedData,
 	series,
 	dataIndexes,
 	activeSeriesIndex,
@@ -67,6 +76,7 @@ export function buildTooltipContent({
 	syncFilterMode,
 }: {
 	data: AlignedData;
+	unstackedData?: AlignedData;
 	series: Series[];
 	dataIndexes: Array<number | null>;
 	activeSeriesIndex: number | null;
@@ -115,6 +125,7 @@ export function buildTooltipContent({
 
 		const baseValue = getTooltipBaseValue({
 			data,
+			unstackedData,
 			index: seriesIndex,
 			dataIndex,
 			isStackedBarChart,

frontend/src/lib/uPlotV2/components/types.ts

@@ -69,6 +69,11 @@ export interface TooltipRenderArgs {
 	syncedSeriesIndexes?: number[] | null;
 	/** Receiver-side filter mode for the synced tooltip. Defaults to Filtered. */
 	syncFilterMode?: SyncTooltipFilterMode;
+	/**
+	 * Pre-stack values, injected by `ChartWrapper`. `Percent` discards the column total,
+	 * so the raw value cannot be recovered from the plot's own cumulative data.
+	 */
+	unstackedData?: uPlot.AlignedData;
 }
 
 export interface IRenderTooltipFooterArgs {

frontend/src/lib/uPlotV2/config/UPlotConfigBuilder.ts

@@ -20,6 +20,7 @@ import {
 	ConfigBuilderProps,
 	LegendItem,
 	SelectionPreferencesSource,
+	StackMode,
 } from './types';
 import { AxisProps, UPlotAxisBuilder } from './UPlotAxisBuilder';
 import { ScaleProps, UPlotScaleBuilder } from './UPlotScaleBuilder';
@@ -28,6 +29,11 @@ import { SeriesProps, UPlotSeriesBuilder } from './UPlotSeriesBuilder';
 /**
  * Type definitions for uPlot option objects
  */
+/** Renders a 0–100 number as `50%`, unlike the 0–1 `percentunit`. */
+const PERCENT_AXIS_UNIT = 'percent';
+
+const PERCENT_AXIS_MAX = 100;
+
 type LegendConfig = {
 	show?: boolean;
 	live?: boolean;
@@ -57,6 +63,8 @@ export class UPlotConfigBuilder extends ConfigBuilder<
 
 	private bands: uPlot.Band[] = [];
 
+	private stackMode: StackMode = StackMode.None;
+
 	private cursor: Cursor | undefined;
 
 	private hooks: Hooks.Arrays = {};
@@ -143,6 +151,15 @@ export class UPlotConfigBuilder extends ConfigBuilder<
 		this.axes[scaleKey] = new UPlotAxisBuilder(props);
 	}
 
+	/** Drives the fill bands, the percent axis unit and the percent range below. */
+	setStackMode(stackMode: StackMode): void {
+		this.stackMode = stackMode;
+	}
+
+	getStackMode(): StackMode {
+		return this.stackMode;
+	}
+
 	/**
 	 * Add or merge a scale configuration
 	 */
@@ -211,6 +228,41 @@ export class UPlotConfigBuilder extends ConfigBuilder<
 		this.bands = bands;
 	}
 
+	/**
+	 * The panel's own limits are in the source unit, which means nothing once values are
+	 * normalised. Soft rather than hard, so mixed-sign shares outside 0–100 stay visible.
+	 */
+	private resolveScale(scale: UPlotScaleBuilder): UPlotScaleBuilder {
+		if (this.stackMode !== StackMode.Percent || scale.props.scaleKey !== 'y') {
+			return scale;
+		}
+		return new UPlotScaleBuilder({
+			...scale.props,
+			min: undefined,
+			max: undefined,
+			softMin: 0,
+			softMax: PERCENT_AXIS_MAX,
+			// Thresholds still draw, but a 500ms one must not stretch the axis to 0–500.
+			thresholds: undefined,
+		});
+	}
+
+	/** Explicit bands win; otherwise a stack fills between consecutive series. */
+	private resolveBands(): uPlot.Band[] | undefined {
+		if (this.bands.length > 0) {
+			return this.bands;
+		}
+		if (this.stackMode === StackMode.None || this.series.length < 2) {
+			return undefined;
+		}
+		return (
+			this.series
+				.slice(0, -1)
+				// uPlot series are 1-based (index 0 is the timestamp axis).
+				.map((_, index) => ({ series: [index + 1, index + 2] as [number, number] }))
+		);
+	}
+
 	/**
 	 * Set cursor configuration
 	 */
@@ -444,9 +496,19 @@ export class UPlotConfigBuilder extends ConfigBuilder<
 				};
 			}),
 		];
-		config.axes = Object.values(this.axes).map((a) => a.getConfig());
+		config.axes = Object.entries(this.axes).map(([scaleKey, axis]) => {
+			if (scaleKey !== 'y' || this.stackMode !== StackMode.Percent) {
+				return axis.getConfig();
+			}
+			// Ticks read as percentages; the panel unit still applies to tooltips and
+			// thresholds, so build from a copy rather than touching the axis props.
+			return new UPlotAxisBuilder({
+				...axis.props,
+				yAxisUnit: PERCENT_AXIS_UNIT,
+			}).getConfig();
+		});
 		config.scales = this.scales.reduce(
-			(acc, s) => ({ ...acc, ...s.getConfig() }),
+			(acc, s) => ({ ...acc, ...this.resolveScale(s).getConfig() }),
 			{} as Record<string, uPlot.Scale>,
 		);
 
@@ -456,7 +518,7 @@ export class UPlotConfigBuilder extends ConfigBuilder<
 		config.cursor = this.getCursorConfig();
 		config.tzDate = this.tzDate;
 		config.plugins = this.plugins.length > 0 ? this.plugins : undefined;
-		config.bands = this.bands.length > 0 ? this.bands : undefined;
+		config.bands = this.resolveBands();
 
 		if (Array.isArray(this.padding)) {
 			config.padding = this.padding;

frontend/src/lib/uPlotV2/config/__tests__/UPlotConfigBuilder.test.ts

@@ -5,7 +5,7 @@ import {
 	STEP_INTERVAL_MULTIPLIER,
 } from '../../constants';
 import type { SeriesProps } from '../types';
-import { DrawStyle, SelectionPreferencesSource } from '../types';
+import { DrawStyle, SelectionPreferencesSource, StackMode } from '../types';
 import { UPlotConfigBuilder } from '../UPlotConfigBuilder';
 
 // Mock only the real boundary that hits localStorage
@@ -496,3 +496,161 @@ describe('UPlotConfigBuilder', () => {
 		expect(config.bands).toBeUndefined();
 	});
 });
+
+describe('UPlotConfigBuilder stacking', () => {
+	beforeEach(() => {
+		jest.clearAllMocks();
+		getStoredSeriesVisibilityMock.getStoredSeriesVisibility.mockReturnValue([]);
+	});
+
+	/**
+	 * Soft limits end up captured in the scale's range closure, so the only way to read
+	 * them back is to run it and inspect the range config it hands uPlot.
+	 */
+	function scaleSoftLimits(
+		builder: UPlotConfigBuilder,
+		scaleKey: string,
+	): { min: number; max: number } {
+		const rangeNum = jest.fn().mockReturnValue([0, 0]);
+		(uPlot as unknown as { rangeNum: unknown }).rangeNum = rangeNum;
+
+		const range = builder.getConfig().scales?.[scaleKey]?.range as (
+			u: unknown,
+			min: number,
+			max: number,
+			key: string,
+		) => void;
+		range({ scales: { [scaleKey]: { distr: 1 } } }, 40, 60, scaleKey);
+
+		const [, , rangeConfig] = rangeNum.mock.calls[0] as [
+			number,
+			number,
+			{ min: { soft: number }; max: { soft: number } },
+		];
+		return { min: rangeConfig.min.soft, max: rangeConfig.max.soft };
+	}
+
+	/** Renders y-axis ticks the way uPlot would, so unit formatting is observable. */
+	function yAxisTicks(builder: UPlotConfigBuilder, ticks: number[]): string[] {
+		const yAxis = builder.getConfig().axes?.find((a) => a.scale === 'y');
+		const values = yAxis?.values as (
+			u: unknown,
+			splits: number[],
+		) => (string | null)[];
+		return values(null, ticks).map((v) => String(v));
+	}
+
+	function builderFor(stack?: StackMode, seriesCount = 3): UPlotConfigBuilder {
+		const builder = new UPlotConfigBuilder({ id: 'stack-test' });
+		if (stack) {
+			builder.setStackMode(stack);
+		}
+		builder.addAxis({ scaleKey: 'y', show: true, side: 3, yAxisUnit: 'ms' });
+		for (let i = 0; i < seriesCount; i++) {
+			builder.addSeries({
+				scaleKey: 'y',
+				label: `S${i}`,
+				drawStyle: DrawStyle.Bar,
+				colorMapping: {},
+				isDarkMode: false,
+			} as SeriesProps);
+		}
+		return builder;
+	}
+
+	it('defaults to no stacking, so no bands and the panel unit on the axis', () => {
+		const builder = builderFor();
+
+		expect(builder.getStackMode()).toBe('none');
+		expect(builder.getConfig().bands).toBeUndefined();
+		expect(yAxisTicks(builder, [1000])).toStrictEqual(['1 s']);
+	});
+
+	it('derives one band per adjacent series pair once a stack is declared', () => {
+		expect(builderFor(StackMode.Normal).getConfig().bands).toStrictEqual([
+			{ series: [1, 2] },
+			{ series: [2, 3] },
+		]);
+	});
+
+	it('emits no bands for a single series', () => {
+		expect(builderFor(StackMode.Normal, 1).getConfig().bands).toBeUndefined();
+	});
+
+	it('keeps the panel unit on the axis for a normal stack', () => {
+		expect(yAxisTicks(builderFor(StackMode.Normal), [1000])).toStrictEqual([
+			'1 s',
+		]);
+	});
+
+	it('formats the axis as percentages for a percent stack', () => {
+		expect(yAxisTicks(builderFor(StackMode.Percent), [0, 50, 100])).toStrictEqual(
+			['0%', '50%', '100%'],
+		);
+	});
+
+	it('leaves other axes on their own unit under a percent stack', () => {
+		const builder = builderFor(StackMode.Percent);
+		builder.addAxis({ scaleKey: 'x', show: true, side: 2 });
+
+		expect(builder.getConfig().axes?.map((a) => a.scale)).toStrictEqual([
+			'y',
+			'x',
+		]);
+	});
+
+	it('pins the y scale to the 0–100 band under a percent stack, dropping panel limits', () => {
+		const builder = new UPlotConfigBuilder({ id: 'stack-scale' });
+		builder.setStackMode(StackMode.Percent);
+		builder.addScale({ scaleKey: 'y', softMin: 5, softMax: 500 });
+
+		// Soft, not hard: mixed-sign shares fall outside 0–100 and must stay visible.
+		expect(builder.getConfig().scales?.y).toMatchObject({ auto: true });
+		expect(scaleSoftLimits(builder, 'y')).toStrictEqual({ min: 0, max: 100 });
+	});
+
+	it('leaves the panel limits alone when the stack is not percent', () => {
+		const builder = new UPlotConfigBuilder({ id: 'stack-scale' });
+		builder.setStackMode(StackMode.Normal);
+		builder.addScale({ scaleKey: 'y', softMin: 5, softMax: 500 });
+
+		expect(scaleSoftLimits(builder, 'y')).toStrictEqual({ min: 5, max: 500 });
+	});
+
+	it.each([StackMode.Normal, StackMode.Percent])(
+		'draws thresholds under a %s stack',
+		(stack) => {
+			const builder = new UPlotConfigBuilder({ id: 'stack-thr' });
+			builder.setStackMode(stack);
+			builder.addThresholds({
+				scaleKey: 'y',
+				thresholds: [{ thresholdValue: 500, thresholdColor: 'red' }],
+				yAxisUnit: 'ms',
+			});
+
+			expect(builder.getConfig().hooks?.draw).toHaveLength(1);
+		},
+	);
+
+	it('keeps a source-unit threshold from stretching the percent band', () => {
+		const builder = new UPlotConfigBuilder({ id: 'stack-thr' });
+		builder.setStackMode(StackMode.Percent);
+		const thresholds = {
+			scaleKey: 'y',
+			thresholds: [{ thresholdValue: 500, thresholdColor: 'red' }],
+			yAxisUnit: 'ms',
+		};
+		builder.addThresholds(thresholds);
+		builder.addScale({ scaleKey: 'y', thresholds });
+
+		// Without this the 500ms threshold would widen a percentage axis to 0–500.
+		expect(scaleSoftLimits(builder, 'y')).toStrictEqual({ min: 0, max: 100 });
+	});
+
+	it('lets explicit bands win over the derived ones', () => {
+		const builder = builderFor(StackMode.Normal);
+		builder.setBands([{ series: [1, 3] }]);
+
+		expect(builder.getConfig().bands).toStrictEqual([{ series: [1, 3] }]);
+	});
+});

frontend/src/lib/uPlotV2/config/types.ts

@@ -33,6 +33,13 @@ export enum SelectionPreferencesSource {
 /**
  * Props for configuring the uPlot config builder
  */
+/** `Percent` rescales each x-slice to its column total, so every column fills to 100. */
+export enum StackMode {
+	None = 'none',
+	Normal = 'normal',
+	Percent = 'percent',
+}
+
 export interface ConfigBuilderProps {
 	id: string;
 	onDragSelect?: (startTime: number, endTime: number) => void;

frontend/src/lib/uPlotV2/utils/__tests__/dataUtils.test.ts

@@ -281,3 +281,20 @@ describe('dataUtils', () => {
 		});
 	});
 });
+
+describe('insertLargeGapNullsIntoAlignedData index alignment', () => {
+	// ChartWrapper gap-processes the pre-stack series to keep tooltip indices aligned;
+	// that only holds because insertions are decided from the x axis, never from y.
+	it('inserts at the same positions regardless of the y values', () => {
+		const x = [0, 100, 200];
+		const options = [{ spanGaps: 50 }];
+		const raw = [x, [1, 2, 3]] as uPlot.AlignedData;
+		const stacked = [x, [10, 20, 30]] as uPlot.AlignedData;
+
+		const fromRaw = insertLargeGapNullsIntoAlignedData(raw, options);
+		const fromStacked = insertLargeGapNullsIntoAlignedData(stacked, options);
+
+		expect(fromRaw[0]).toStrictEqual(fromStacked[0]);
+		expect(fromRaw[1]).toHaveLength((fromStacked[1] as unknown[]).length);
+	});
+});

frontend/src/pages/DashboardPageV2/DashboardContainer/Panels/kinds/BarChartPanel/Renderer.tsx

@@ -7,6 +7,7 @@ import { PanelMode } from 'container/DashboardContainer/visualization/panels/typ
 import { useIsDarkMode } from 'hooks/useDarkMode';
 import { useResizeObserver } from 'hooks/useDimensions';
 import { IRenderTooltipFooterArgs } from 'lib/uPlotV2/components/types';
+import { StackMode } from 'lib/uPlotV2/config/types';
 import {
 	flattenTimeSeries,
 	getExecStats,
@@ -219,7 +220,9 @@ function BarPanelRenderer({
 						height={containerDimensions.height}
 						syncMode={dashboardPreference?.syncMode}
 						syncFilterMode={dashboardPreference?.syncFilterMode}
-						isStackedBarChart={spec.visualization?.stackedBarChart ?? false}
+						stack={
+							spec.visualization?.stackedBarChart ? StackMode.Normal : StackMode.None
+						}
 						renderTooltipFooter={renderTooltipFooter}
 						onClick={enableDrillDown ? handleChartClick : undefined}
 					/>

frontend/src/pages/DashboardPageV2/DashboardContainer/Panels/kinds/BarChartPanel/utils/buildConfig.ts

@@ -1,7 +1,6 @@
 import type { DashboardtypesBarChartPanelSpecDTO } from 'api/generated/services/sigNoz.schemas';
 import { Timezone } from 'components/CustomTimePicker/timezoneUtils';
 import { PANEL_TYPES } from 'constants/queryBuilder';
-import { getInitialStackedBands } from 'container/DashboardContainer/visualization/charts/utils/stackSeriesUtils';
 import { PanelMode } from 'container/DashboardContainer/visualization/panels/types';
 import { buildBaseConfig } from 'pages/DashboardPageV2/DashboardContainer/Panels/utils/baseConfigBuilder';
 import { resolveSeriesLabelV5 } from 'pages/DashboardPageV2/DashboardContainer/Panels/utils/resolveSeriesLabel';
@@ -101,12 +100,6 @@ function addSeries({
 }: AddSeriesArgs): void {
 	const colorMapping = spec.legend?.customColors ?? {};
 
-	if (spec.visualization?.stackedBarChart) {
-		// uPlot uses 1-based series indices (index 0 is the timestamp axis);
-		// `+1` keeps the band targets aligned with the series we're about to add.
-		builder.setBands(getInitialStackedBands(series.length + 1));
-	}
-
 	series.forEach((s) => {
 		const baseLabel = getLabelName(s.labels, s.queryName, s.legend);
 		const label = resolveSeriesLabelV5(s, builderQueries, baseLabel);

pkg/modules/cloudintegration/implcloudintegration/fs/definitions/aws/lambda/assets/dashboards/overview.json

@@ -51,6 +51,28 @@
           },
           "name": "Region"
         }
+      },
+      {
+        "kind": "ListVariable",
+        "spec": {
+          "display": {
+            "name": "FunctionName",
+            "description": "Name of the Lambda function"
+          },
+          "allowAllValue": true,
+          "allowMultiple": true,
+          "customAllValue": "",
+          "capturingRegexp": "",
+          "sort": "none",
+          "plugin": {
+            "kind": "signoz/DynamicVariable",
+            "spec": {
+              "name": "FunctionName",
+              "signal": "metrics"
+            }
+          },
+          "name": "FunctionName"
+        }
       }
     ],
     "panels": {
@@ -118,7 +140,7 @@
                     ],
                     "disabled": false,
                     "filter": {
-                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS)"
+                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS) AND FunctionName IN $FunctionName"
                     },
                     "groupBy": [
                       {
@@ -218,7 +240,7 @@
                     ],
                     "disabled": false,
                     "filter": {
-                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS)"
+                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS) AND FunctionName IN $FunctionName"
                     },
                     "groupBy": [
                       {
@@ -318,7 +340,7 @@
                     ],
                     "disabled": false,
                     "filter": {
-                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS)"
+                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS) AND FunctionName IN $FunctionName"
                     },
                     "groupBy": [
                       {
@@ -418,7 +440,7 @@
                     ],
                     "disabled": false,
                     "filter": {
-                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS)"
+                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS) AND FunctionName IN $FunctionName"
                     },
                     "groupBy": [
                       {
@@ -518,7 +540,7 @@
                     ],
                     "disabled": false,
                     "filter": {
-                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS)"
+                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS) AND FunctionName IN $FunctionName"
                     },
                     "groupBy": [
                       {
@@ -618,7 +640,7 @@
                     ],
                     "disabled": false,
                     "filter": {
-                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS)"
+                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS) AND FunctionName IN $FunctionName"
                     },
                     "groupBy": [
                       {
@@ -718,7 +740,7 @@
                     ],
                     "disabled": false,
                     "filter": {
-                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS)"
+                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS) AND FunctionName IN $FunctionName"
                     },
                     "groupBy": [
                       {
@@ -831,4 +853,4 @@
     "refreshInterval": "",
     "links": []
   }
-}
+}

pkg/signoz/provider.go

@@ -242,6 +242,7 @@ func NewSQLMigrationProviderFactories(
 		sqlmigration.NewRestructureAuthDomainConfigFactory(sqlstore),
 		sqlmigration.NewFixSavedViewSelectFieldsFactory(sqlstore),
 		sqlmigration.NewDeleteOrphanUserRolesFactory(),
+		sqlmigration.NewMigrateLambdaDashboardsFactory(),
 	)
 }
 

pkg/sqlmigration/116_migrate_lambda_dashboards.go

@@ -0,0 +1,160 @@
+package sqlmigration
+
+import (
+	"bytes"
+	"context"
+	"embed"
+	"encoding/json"
+	"time"
+
+	"github.com/SigNoz/signoz/pkg/factory"
+	"github.com/uptrace/bun"
+	"github.com/uptrace/bun/migrate"
+)
+
+//go:embed 116_migrate_lambda_dashboards
+var lambdaDashboardFiles embed.FS
+
+// These values mirror the cloud integration and dashboard packages but are duplicated
+// here so this migration keeps targeting and writing the same rows even if those
+// constants are later renamed or changed.
+const (
+	lambdaDashboardFile = "116_migrate_lambda_dashboards/aws/lambda/overview.json"
+
+	lambdaDashboardSlug               = "aws-lambda-overview"
+	cloudIntegrationDashboardProvider = "cloud_integration"
+	integrationDashboardSource        = "integration"
+	dashboardSchemaVersion            = "v6"
+)
+
+type migrateLambdaDashboards struct{}
+
+type lambdaDashboardRow struct {
+	bun.BaseModel `bun:"table:dashboard,alias:dashboard"`
+
+	ID   string `bun:"id"`
+	Data string `bun:"data"`
+}
+
+// lambdaDashboardDefinition is the part of the embedded dashboard this migration reads:
+// its spec, which is what the cloud integration stores under data.spec.
+type lambdaDashboardDefinition struct {
+	Spec map[string]any `json:"spec"`
+}
+
+func NewMigrateLambdaDashboardsFactory() factory.ProviderFactory[SQLMigration, Config] {
+	return factory.NewProviderFactory(
+		factory.MustNewName("migrate_lambda_dashboards"),
+		func(ctx context.Context, ps factory.ProviderSettings, c Config) (SQLMigration, error) {
+			return &migrateLambdaDashboards{}, nil
+		},
+	)
+}
+
+func (m *migrateLambdaDashboards) Register(migrations *migrate.Migrations) error {
+	return migrations.Register(m.Up, m.Down)
+}
+
+// Up rewrites the spec of every provisioned AWS Lambda overview dashboard to the
+// embedded revision that added the FunctionName variable. Cloud integration dashboards
+// are provisioned once and never updated afterwards, so existing installs only pick up
+// this change through a migration. Only the spec is replaced; the row keeps its id, name,
+// tags and metadata, so the dashboard is updated in place rather than recreated.
+func (m *migrateLambdaDashboards) Up(ctx context.Context, db *bun.DB) error {
+	spec, err := m.loadSpec()
+	if err != nil {
+		return err
+	}
+
+	tx, err := db.BeginTx(ctx, nil)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = tx.Rollback() }()
+
+	var rows []*lambdaDashboardRow
+	if err := tx.NewSelect().
+		Model(&rows).
+		Join("JOIN integration_dashboard AS id ON id.dashboard_id = dashboard.id").
+		Where("id.provider = ?", cloudIntegrationDashboardProvider).
+		Where("id.slug = ?", lambdaDashboardSlug).
+		Where("dashboard.source = ?", integrationDashboardSource).
+		Scan(ctx); err != nil {
+		return err
+	}
+
+	for _, row := range rows {
+		data := map[string]any{}
+		if err := json.Unmarshal([]byte(row.Data), &data); err != nil {
+			return err
+		}
+
+		// The embedded spec is v6-shaped, so only rewrite a row already carrying a v6 spec;
+		// anything else is left alone rather than turned into a broken mix of versions.
+		if !m.hasV6Spec(data) {
+			continue
+		}
+		data["spec"] = spec
+
+		encoded, err := m.marshalUnescaped(data)
+		if err != nil {
+			return err
+		}
+		// Skip rows already carrying this spec so a re-run does not needlessly rewrite them.
+		if string(encoded) == row.Data {
+			continue
+		}
+
+		if _, err := tx.NewUpdate().
+			Model((*lambdaDashboardRow)(nil)).
+			Set("data = ?", string(encoded)).
+			Set("updated_at = ?", time.Now()).
+			Where("id = ?", row.ID).
+			Exec(ctx); err != nil {
+			return err
+		}
+	}
+
+	return tx.Commit()
+}
+
+func (m *migrateLambdaDashboards) Down(context.Context, *bun.DB) error {
+	return nil
+}
+
+// hasV6Spec reports whether the stored data is a v6 dashboard with a spec object, which
+// is the shape whose spec this migration replaces.
+func (m *migrateLambdaDashboards) hasV6Spec(data map[string]any) bool {
+	metadata, _ := data["metadata"].(map[string]any)
+	version, _ := metadata["schemaVersion"].(string)
+	if version != dashboardSchemaVersion {
+		return false
+	}
+	_, ok := data["spec"].(map[string]any)
+	return ok
+}
+
+func (m *migrateLambdaDashboards) marshalUnescaped(v any) ([]byte, error) {
+	var buf bytes.Buffer
+	encoder := json.NewEncoder(&buf)
+	encoder.SetEscapeHTML(false)
+	if err := encoder.Encode(v); err != nil {
+		return nil, err
+	}
+
+	return bytes.TrimRight(buf.Bytes(), "\n"), nil
+}
+
+func (m *migrateLambdaDashboards) loadSpec() (map[string]any, error) {
+	raw, err := lambdaDashboardFiles.ReadFile(lambdaDashboardFile)
+	if err != nil {
+		return nil, err
+	}
+
+	var dashboard lambdaDashboardDefinition
+	if err := json.Unmarshal(raw, &dashboard); err != nil {
+		return nil, err
+	}
+
+	return dashboard.Spec, nil
+}

pkg/sqlmigration/116_migrate_lambda_dashboards/aws/lambda/overview.json

@@ -0,0 +1,856 @@
+{
+  "schemaVersion": "v6",
+  "image": "data:image/svg+xml;base64,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",
+  "name": "",
+  "generateName": true,
+  "tags": [],
+  "spec": {
+    "display": {
+      "name": "AWS Lambda Overview",
+      "description": "Overview of AWS Lambda functions"
+    },
+    "variables": [
+      {
+        "kind": "ListVariable",
+        "spec": {
+          "display": {
+            "name": "Account",
+            "description": "AWS Account"
+          },
+          "allowAllValue": false,
+          "allowMultiple": false,
+          "customAllValue": "",
+          "capturingRegexp": "",
+          "sort": "none",
+          "plugin": {
+            "kind": "signoz/QueryVariable",
+            "spec": {
+              "queryValue": "SELECT JSONExtractString(labels, 'cloud.account.id') as `cloud.account.id`\nFROM signoz_metrics.distributed_time_series_v4_1day\nWHERE \n    metric_name like 'aws_Lambda_Invocations_sum'\nGROUP BY `cloud.account.id`\n\n"
+            }
+          },
+          "name": "Account"
+        }
+      },
+      {
+        "kind": "ListVariable",
+        "spec": {
+          "display": {
+            "name": "Region",
+            "description": "AWS Region"
+          },
+          "allowAllValue": false,
+          "allowMultiple": false,
+          "customAllValue": "",
+          "capturingRegexp": "",
+          "sort": "none",
+          "plugin": {
+            "kind": "signoz/QueryVariable",
+            "spec": {
+              "queryValue": "SELECT JSONExtractString(labels, 'cloud.region') as `cloud.region`\nFROM signoz_metrics.distributed_time_series_v4_1day\nWHERE \n    metric_name like 'aws_Lambda_Invocations_sum'\n    and JSONExtractString(labels, 'cloud.account.id') IN {{.Account}}\nGROUP BY `cloud.region`\n"
+            }
+          },
+          "name": "Region"
+        }
+      },
+      {
+        "kind": "ListVariable",
+        "spec": {
+          "display": {
+            "name": "FunctionName",
+            "description": "Name of the Lambda function"
+          },
+          "allowAllValue": true,
+          "allowMultiple": true,
+          "customAllValue": "",
+          "capturingRegexp": "",
+          "sort": "none",
+          "plugin": {
+            "kind": "signoz/DynamicVariable",
+            "spec": {
+              "name": "FunctionName",
+              "signal": "metrics"
+            }
+          },
+          "name": "FunctionName"
+        }
+      }
+    ],
+    "panels": {
+      "2516c785-b025-49b3-aeb4-a4735ccb2709": {
+        "kind": "Panel",
+        "spec": {
+          "display": {
+            "name": "Errors",
+            "description": "The number of invocations that result in a function error. Function errors include exceptions that your code throws and exceptions that the Lambda runtime throws. The runtime returns errors for issues such as timeouts and configuration errors. To calculate the error rate, divide the value of Errors by the value of Invocations. Note that the timestamp on an error metric reflects when the function was invoked, not when the error occurred.\n\nSee more at https://docs.aws.amazon.com/lambda/latest/dg/monitoring-metrics-types.html"
+          },
+          "plugin": {
+            "kind": "signoz/TimeSeriesPanel",
+            "spec": {
+              "visualization": {
+                "timePreference": "global_time",
+                "fillSpans": false
+              },
+              "formatting": {
+                "unit": "none",
+                "decimalPrecision": "2"
+              },
+              "chartAppearance": {
+                "lineInterpolation": "spline",
+                "showPoints": false,
+                "lineStyle": "solid",
+                "fillMode": "none",
+                "spanGaps": {
+                  "fillOnlyBelow": false,
+                  "fillLessThan": ""
+                }
+              },
+              "axes": {
+                "softMin": 0,
+                "softMax": 0,
+                "isLogScale": false
+              },
+              "legend": {
+                "position": "bottom",
+                "mode": "list",
+                "customColors": null
+              },
+              "thresholds": null
+            }
+          },
+          "queries": [
+            {
+              "kind": "time_series",
+              "spec": {
+                "name": "A",
+                "plugin": {
+                  "kind": "signoz/BuilderQuery",
+                  "spec": {
+                    "name": "A",
+                    "stepInterval": 60,
+                    "signal": "metrics",
+                    "source": "",
+                    "aggregations": [
+                      {
+                        "metricName": "aws_Lambda_Errors_sum",
+                        "temporality": "",
+                        "timeAggregation": "sum",
+                        "spaceAggregation": "sum",
+                        "reduceTo": "avg"
+                      }
+                    ],
+                    "disabled": false,
+                    "filter": {
+                      "expression": "(cloud.account.id = $Account AND cloud.region = $Region AND FunctionName EXISTS AND Resource NOT EXISTS) AND FunctionName IN $FunctionName"
+                    },
+                    "groupBy": [
+                      {
+                        "name": "cloud.account.id",
+                        "signal": "",
+                        "fieldContext": "attribute",
+                        "fieldDataType": "string"
+                      },
+                      {
+                        "name": "cloud.region",
+                        "signal": "",
+                        "fieldContext": "attribute",
+                        "fieldDataType": "string"
+                      },
+                      {
+                        "name": "FunctionName",
+                        "signal": "",
+                        "fieldContext": "attribute",
+                        "fieldDataType": "string"
+                      }
+                    ],
+                    "order": [],
+                    "having": {
+                      "expression": ""
+                    },
+                    "functions": [],
+                    "legend": "{{FunctionName}}"
+                  }
+                }
+              }
+            }
+          ],
+          "links": []
+        }
+      },
+      "4119a1e5-32a8-4859-96e9-a5451114782b": {
+        "kind": "Panel",
+        "spec": {
+          "display": {
+            "name": "Async events dropped",
+            "description": "The number of events that are dropped without successfully executing the function. If you configure a dead-letter queue (DLQ) or OnFailure destination, then events are sent there before they're dropped. Events are dropped for various reasons. For example, events can exceed the maximum event age or exhaust the maximum retry attempts, or reserved concurrency might be set to 0. To troubleshoot why events are dropped, look at the Errors metric to identify function errors and the Throttles metric to identify concurrency issues.\n\nSee more at https://docs.aws.amazon.com/lambda/latest/dg/monitoring-metrics-types.html"
+          },
+          "plugin": {
+            "kind": "signoz/TimeSeriesPanel",
+            "spec": {
+              "visualization": {
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