feat: add trace details v3 flamegraph

Canvas-based flamegraph with:
- Zoom/pan via drag with scroll support
- Span hover cards with event tooltips
- Click to select span (drag detection)
- Web worker for visual layout computation
- TimelineV3 ruler component
- V3 color palette for service differentiation
- Flamegraph limit parameter (120k spans)

cmd/community/server.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/SigNoz/signoz/cmd"
 	"github.com/SigNoz/signoz/pkg/analytics"
+	"github.com/SigNoz/signoz/pkg/auditor"
 	"github.com/SigNoz/signoz/pkg/authn"
 	"github.com/SigNoz/signoz/pkg/authz"
 	"github.com/SigNoz/signoz/pkg/authz/openfgaauthz"
@@ -93,6 +94,9 @@ func runServer(ctx context.Context, config signoz.Config, logger *slog.Logger) e
 		func(_ licensing.Licensing) factory.ProviderFactory[gateway.Gateway, gateway.Config] {
 			return noopgateway.NewProviderFactory()
 		},
+		func(_ licensing.Licensing) factory.NamedMap[factory.ProviderFactory[auditor.Auditor, auditor.Config]] {
+			return signoz.NewAuditorProviderFactories()
+		},
 		func(ps factory.ProviderSettings, q querier.Querier, a analytics.Analytics) querier.Handler {
 			return querier.NewHandler(ps, q, a)
 		},

cmd/enterprise/server.go

@@ -8,6 +8,7 @@ import (
 	"github.com/spf13/cobra"
 
 	"github.com/SigNoz/signoz/cmd"
+	"github.com/SigNoz/signoz/ee/auditor/otlphttpauditor"
 	"github.com/SigNoz/signoz/ee/authn/callbackauthn/oidccallbackauthn"
 	"github.com/SigNoz/signoz/ee/authn/callbackauthn/samlcallbackauthn"
 	"github.com/SigNoz/signoz/ee/authz/openfgaauthz"
@@ -24,6 +25,7 @@ import (
 	enterprisezeus "github.com/SigNoz/signoz/ee/zeus"
 	"github.com/SigNoz/signoz/ee/zeus/httpzeus"
 	"github.com/SigNoz/signoz/pkg/analytics"
+	"github.com/SigNoz/signoz/pkg/auditor"
 	"github.com/SigNoz/signoz/pkg/authn"
 	"github.com/SigNoz/signoz/pkg/authz"
 	"github.com/SigNoz/signoz/pkg/errors"
@@ -133,6 +135,13 @@ func runServer(ctx context.Context, config signoz.Config, logger *slog.Logger) e
 		func(licensing licensing.Licensing) factory.ProviderFactory[gateway.Gateway, gateway.Config] {
 			return httpgateway.NewProviderFactory(licensing)
 		},
+		func(licensing licensing.Licensing) factory.NamedMap[factory.ProviderFactory[auditor.Auditor, auditor.Config]] {
+			factories := signoz.NewAuditorProviderFactories()
+			if err := factories.Add(otlphttpauditor.NewFactory(licensing, version.Info)); err != nil {
+				panic(err)
+			}
+			return factories
+		},
 		func(ps factory.ProviderSettings, q querier.Querier, a analytics.Analytics) querier.Handler {
 			communityHandler := querier.NewHandler(ps, q, a)
 			return eequerier.NewHandler(ps, q, communityHandler)

conf/example.yaml

@@ -364,3 +364,34 @@ serviceaccount:
   analytics:
     # toggle service account analytics
     enabled: true
+
+##################### Auditor #####################
+auditor:
+  # Specifies the auditor provider to use.
+  # noop: discards all audit events (community default).
+  # otlphttp: exports audit events via OTLP HTTP (enterprise).
+  provider: noop
+  # The async channel capacity for audit events. Events are dropped when full (fail-open).
+  buffer_size: 1000
+  # The maximum number of events per export batch.
+  batch_size: 100
+  # The maximum time between export flushes.
+  flush_interval: 1s
+  otlphttp:
+    # The target scheme://host:port/path of the OTLP HTTP endpoint.
+    endpoint: http://localhost:4318/v1/logs
+    # Whether to use HTTP instead of HTTPS.
+    insecure: false
+    # The maximum duration for an export attempt.
+    timeout: 10s
+    # Additional HTTP headers sent with every export request.
+    headers: {}
+    retry:
+      # Whether to retry on transient failures.
+      enabled: true
+      # The initial wait time before the first retry.
+      initial_interval: 5s
+      # The upper bound on backoff interval.
+      max_interval: 30s
+      # The total maximum time spent retrying.
+      max_elapsed_time: 60s

ee/query-service/app/server.go

@@ -227,7 +227,7 @@ func (s *Server) createPublicServer(apiHandler *api.APIHandler, web web.Web) (*h
 		s.config.APIServer.Timeout.Default,
 		s.config.APIServer.Timeout.Max,
 	).Wrap)
-	r.Use(middleware.NewAudit(s.signoz.Instrumentation.Logger(), s.config.APIServer.Logging.ExcludedRoutes, nil).Wrap)
+	r.Use(middleware.NewAudit(s.signoz.Instrumentation.Logger(), s.config.APIServer.Logging.ExcludedRoutes, s.signoz.Auditor).Wrap)
 	r.Use(middleware.NewComment().Wrap)
 
 	apiHandler.RegisterRoutes(r, am)

frontend/src/components/TimelineV3/TimelineV3.styles.scss

@@ -0,0 +1,4 @@
+.timeline-v3-container {
+	// flex: 1;
+	overflow: visible;
+}

frontend/src/components/TimelineV3/TimelineV3.tsx

@@ -0,0 +1,87 @@
+import { useEffect, useState } from 'react';
+import { useMeasure } from 'react-use';
+import { useIsDarkMode } from 'hooks/useDarkMode';
+
+import {
+	getIntervals,
+	getMinimumIntervalsBasedOnWidth,
+	Interval,
+} from './utils';
+
+import './TimelineV3.styles.scss';
+
+interface ITimelineV3Props {
+	startTimestamp: number;
+	endTimestamp: number;
+	timelineHeight: number;
+	offsetTimestamp: number;
+}
+
+function TimelineV3(props: ITimelineV3Props): JSX.Element {
+	const {
+		startTimestamp,
+		endTimestamp,
+		timelineHeight,
+		offsetTimestamp,
+	} = props;
+	const [intervals, setIntervals] = useState<Interval[]>([]);
+	const [ref, { width }] = useMeasure<HTMLDivElement>();
+	const isDarkMode = useIsDarkMode();
+
+	useEffect(() => {
+		const spread = endTimestamp - startTimestamp;
+		if (spread < 0) {
+			return;
+		}
+
+		const minIntervals = getMinimumIntervalsBasedOnWidth(width);
+		const intervalisedSpread = (spread / minIntervals) * 1.0;
+		const intervals = getIntervals(intervalisedSpread, spread, offsetTimestamp);
+
+		setIntervals(intervals);
+	}, [startTimestamp, endTimestamp, width, offsetTimestamp]);
+
+	if (endTimestamp < startTimestamp) {
+		console.error(
+			'endTimestamp cannot be less than startTimestamp',
+			startTimestamp,
+			endTimestamp,
+		);
+		return <div />;
+	}
+
+	const strokeColor = isDarkMode ? ' rgb(192,193,195,0.8)' : 'black';
+
+	return (
+		<div ref={ref as never} className="timeline-v3-container">
+			<svg
+				width={width}
+				height={timelineHeight * 2.5}
+				xmlns="http://www.w3.org/2000/svg"
+				overflow="visible"
+			>
+				{intervals &&
+					intervals.length > 0 &&
+					intervals.map((interval, index) => (
+						<g
+							transform={`translate(${(interval.percentage * width) / 100},0)`}
+							key={`${interval.percentage + interval.label + index}`}
+							textAnchor="middle"
+							fontSize="0.6rem"
+						>
+							<text
+								x={index === intervals.length - 1 ? -10 : 0}
+								y={timelineHeight * 2}
+								fill={strokeColor}
+							>
+								{interval.label}
+							</text>
+							<line y1={0} y2={timelineHeight} stroke={strokeColor} strokeWidth="1" />
+						</g>
+					))}
+			</svg>
+		</div>
+	);
+}
+
+export default TimelineV3;

frontend/src/components/TimelineV3/utils.ts

@@ -0,0 +1,93 @@
+import {
+	IIntervalUnit,
+	Interval,
+	INTERVAL_UNITS,
+	resolveTimeFromInterval,
+} from 'components/TimelineV2/utils';
+import { toFixed } from 'utils/toFixed';
+
+export type { Interval };
+
+/** Fewer intervals than TimelineV2 for a cleaner flamegraph ruler. */
+export function getMinimumIntervalsBasedOnWidth(width: number): number {
+	if (width < 640) {
+		return 3;
+	}
+	if (width < 768) {
+		return 4;
+	}
+	if (width < 1024) {
+		return 5;
+	}
+	return 6;
+}
+
+/**
+ * Computes timeline intervals with offset-aware labels.
+ * Labels reflect absolute time from trace start (offsetTimestamp + elapsed),
+ * so when zoomed into a window, the first tick shows e.g. "50ms" not "0ms".
+ */
+export function getIntervals(
+	intervalSpread: number,
+	baseSpread: number,
+	offsetTimestamp: number,
+): Interval[] {
+	const integerPartString = intervalSpread.toString().split('.')[0];
+	const integerPartLength = integerPartString.length;
+
+	const intervalSpreadNormalized =
+		intervalSpread < 1.0
+			? intervalSpread
+			: Math.floor(Number(integerPartString) / 10 ** (integerPartLength - 1)) *
+			  10 ** (integerPartLength - 1);
+
+	// Unit must suit both: (1) tick granularity (intervalSpread) and (2) label magnitude
+	// (offsetTimestamp). When zoomed deep into a trace, labels show offsetTimestamp + elapsed,
+	// so we must pick a unit where that value is readable (e.g. "500.00s" not "500000.00ms").
+	const valueForUnitSelection = Math.max(offsetTimestamp, intervalSpread);
+	let intervalUnit: IIntervalUnit = INTERVAL_UNITS[0];
+	for (let idx = INTERVAL_UNITS.length - 1; idx >= 0; idx -= 1) {
+		const standardInterval = INTERVAL_UNITS[idx];
+		if (valueForUnitSelection * standardInterval.multiplier >= 1) {
+			intervalUnit = INTERVAL_UNITS[idx];
+			break;
+		}
+	}
+
+	const intervals: Interval[] = [
+		{
+			label: `${toFixed(
+				resolveTimeFromInterval(offsetTimestamp, intervalUnit),
+				2,
+			)}${intervalUnit.name}`,
+			percentage: 0,
+		},
+	];
+
+	let tempBaseSpread = baseSpread;
+	let elapsedIntervals = 0;
+
+	while (tempBaseSpread && intervals.length < 20) {
+		let intervalTime: number;
+
+		if (tempBaseSpread <= 1.5 * intervalSpreadNormalized) {
+			intervalTime = elapsedIntervals + tempBaseSpread;
+			tempBaseSpread = 0;
+		} else {
+			intervalTime = elapsedIntervals + intervalSpreadNormalized;
+			tempBaseSpread -= intervalSpreadNormalized;
+		}
+
+		elapsedIntervals = intervalTime;
+		const labelTime = offsetTimestamp + intervalTime;
+
+		intervals.push({
+			label: `${toFixed(resolveTimeFromInterval(labelTime, intervalUnit), 2)}${
+				intervalUnit.name
+			}`,
+			percentage: (intervalTime / baseSpread) * 100,
+		});
+	}
+
+	return intervals;
+}

frontend/src/constants/theme.ts

@@ -33,6 +33,125 @@ const themeColors = {
 		purple: '#800080',
 		cyan: '#00FFFF',
 	},
+	traceDetailColorsV3: {
+		// Blues
+		dodgerBlue: '#2F80ED',
+		royalBlue: '#3366E6',
+		steelBlue: '#4682B4',
+
+		// Teals / Cyans
+		turquoise: '#00CEC9',
+		lagoon: '#1ABC9C',
+		cyanBright: '#22A6F2',
+
+		// Greens
+		emeraldGreen: '#27AE60',
+		mediumSeaGreen: '#3CB371',
+		limeGreen: '#A3E635',
+
+		// Yellows / Golds
+		festivalYellow: '#F2C94C',
+		sunflower: '#FFD93D',
+		warmAmber: '#FFCA28',
+
+		// Purples / Violets
+		mediumPurple: '#BB6BD9',
+		royalPurple: '#9B51E0',
+		orchid: '#DA77F2',
+
+		// Accent
+		neonViolet: '#C77DFF',
+		electricPurple: '#6C5CE7',
+		arcticBlue: '#48DBFB',
+
+		// Blues extended
+		blue1: '#1F63E0',
+		blue2: '#3A7AED',
+		blue3: '#5A9DF5',
+		blue4: '#2874A6',
+		blue5: '#2E86C1',
+		blue6: '#3498DB',
+
+		// Cyans
+		cyan1: '#00B0AA',
+		cyan2: '#33D6C2',
+		cyan3: '#66E9DA',
+
+		// Greens extended
+		green1: '#1E8449',
+		green2: '#2ECC71',
+		green3: '#58D68D',
+		green4: '#229954',
+		green5: '#27AE60',
+		green6: '#52BE80',
+
+		// Forest
+		forest1: '#27AE60',
+		forest2: '#2ECC71',
+		forest3: '#58D68D',
+
+		// Lime
+		lime1: '#A3E635',
+		lime2: '#B9F18D',
+		lime3: '#D4FFB0',
+
+		// Teals
+		teal1: '#009688',
+		teal2: '#1ABC9C',
+		teal3: '#48C9B0',
+		teal4: '#1ABC9C',
+		teal5: '#48C9B0',
+		teal6: '#76D7C4',
+
+		// Yellows
+		yellow1: '#F1C40F',
+		yellow2: '#F7DC6F',
+		yellow3: '#F9E79F',
+
+		// Gold
+		gold1: '#F39C12',
+		gold2: '#F1C40F',
+		gold3: '#F7DC6F',
+		gold4: '#B7950B',
+		gold5: '#F1C40F',
+		gold6: '#F4D03F',
+
+		// Mustard
+		mustard1: '#F1C40F',
+		mustard2: '#F7DC6F',
+		mustard3: '#F9E79F',
+
+		// Aqua
+		aqua1: '#00BFFF',
+		aqua2: '#1E90FF',
+		aqua3: '#63B8FF',
+
+		// Purple extended
+		purple1: '#8E44AD',
+		purple2: '#9B59B6',
+		purple3: '#BB8FCE',
+
+		violet1: '#8E44AD',
+		violet2: '#9B59B6',
+		violet3: '#BB8FCE',
+		violet4: '#7D3C98',
+		violet5: '#8E44AD',
+		violet6: '#9B59B6',
+
+		// Lavender
+		lavender1: '#9B59B6',
+		lavender2: '#AF7AC5',
+		lavender3: '#C39BD3',
+
+		// Oranges (safe ones, not red-ish)
+		orange4: '#D35400',
+		orange5: '#E67E22',
+		orange6: '#EB984E',
+
+		coral1: '#E67E22',
+		coral2: '#F39C12',
+		coral3: '#F5B041',
+	},
 	chartcolors: {
 		// Blues (3)
 		dodgerBlue: '#2F80ED',

frontend/src/container/NewWidget/index.tsx

@@ -677,6 +677,18 @@ function NewWidget({
 			queryType: currentQuery.queryType,
 			isNewPanel,
 			dataSource: currentQuery?.builder?.queryData?.[0]?.dataSource,
+			...(currentQuery.queryType === EQueryType.CLICKHOUSE && {
+				clickhouseQueryCount: currentQuery.clickhouse_sql.length,
+				clickhouseQueries: currentQuery.clickhouse_sql.map((q) => ({
+					name: q.name,
+					query: (q.query ?? '')
+						.replace(/--[^\n]*/g, '') // strip line comments
+						.replace(/\/\*[\s\S]*?\*\//g, '') // strip block comments
+						.replace(/'(?:[^'\\]|\\.|'')*'/g, "'?'") // replace single-quoted strings (handles \' and '' escapes)
+						.replace(/\b\d+(?:\.\d+)?(?:[eE][+-]?\d+)?\b/g, '?'), // replace numeric literals (int, float, scientific)
+					disabled: q.disabled,
+				})),
+			}),
 		});
 		setSaveModal(true);
 		// eslint-disable-next-line react-hooks/exhaustive-deps

frontend/src/pages/TraceDetailsV3/SpanHoverCard/EventTooltipContent.styles.scss

@@ -0,0 +1,60 @@
+.event-tooltip-content {
+	font-family: Inter, sans-serif;
+	font-size: 12px;
+	color: #fff;
+	max-width: 300px;
+
+	&__header {
+		display: inline-flex;
+		align-items: center;
+		gap: 4px;
+		background: rgba(255, 255, 255, 0.1);
+		border-radius: 3px;
+		padding: 2px 6px;
+		font-size: 10px;
+		font-weight: 600;
+		text-transform: uppercase;
+		letter-spacing: 0.5px;
+		color: rgba(255, 255, 255, 0.7);
+		margin-bottom: 6px;
+	}
+
+	&__name {
+		font-weight: 600;
+		margin-bottom: 2px;
+		color: rgb(14, 165, 233);
+
+		&.error {
+			color: rgb(239, 68, 68);
+		}
+	}
+
+	&__time {
+		font-size: 11px;
+		opacity: 0.8;
+		margin-bottom: 4px;
+	}
+
+	&__divider {
+		border-top: 1px solid rgba(255, 255, 255, 0.1);
+		margin: 6px 0;
+	}
+
+	&__attributes {
+		font-size: 11px;
+	}
+
+	&__kv {
+		margin-bottom: 2px;
+		line-height: 1.4;
+		word-break: break-all;
+	}
+
+	&__key {
+		opacity: 0.6;
+	}
+
+	&__value {
+		opacity: 0.9;
+	}
+}

frontend/src/pages/TraceDetailsV3/SpanHoverCard/EventTooltipContent.tsx

@@ -0,0 +1,49 @@
+import { convertTimeToRelevantUnit } from 'container/TraceDetail/utils';
+import { Diamond } from 'lucide-react';
+import { toFixed } from 'utils/toFixed';
+
+import './EventTooltipContent.styles.scss';
+
+export interface EventTooltipContentProps {
+	eventName: string;
+	timeOffsetMs: number;
+	isError: boolean;
+	attributeMap: Record<string, string>;
+}
+
+export function EventTooltipContent({
+	eventName,
+	timeOffsetMs,
+	isError,
+	attributeMap,
+}: EventTooltipContentProps): JSX.Element {
+	const { time, timeUnitName } = convertTimeToRelevantUnit(timeOffsetMs);
+
+	return (
+		<div className="event-tooltip-content">
+			<div className="event-tooltip-content__header">
+				<Diamond size={10} />
+				<span>EVENT DETAILS</span>
+			</div>
+			<div className={`event-tooltip-content__name ${isError ? 'error' : ''}`}>
+				{eventName}
+			</div>
+			<div className="event-tooltip-content__time">
+				{toFixed(time, 2)} {timeUnitName} from start
+			</div>
+			{Object.keys(attributeMap).length > 0 && (
+				<>
+					<div className="event-tooltip-content__divider" />
+					<div className="event-tooltip-content__attributes">
+						{Object.entries(attributeMap).map(([key, value]) => (
+							<div key={key} className="event-tooltip-content__kv">
+								<span className="event-tooltip-content__key">{key}:</span>{' '}
+								<span className="event-tooltip-content__value">{value}</span>
+							</div>
+						))}
+					</div>
+				</>
+			)}
+		</div>
+	);
+}

frontend/src/pages/TraceDetailsV3/SpanHoverCard/SpanHoverCard.styles.scss

@@ -0,0 +1,28 @@
+.span-hover-card-popover {
+	.ant-popover-inner {
+		background-color: rgba(30, 30, 30, 0.95);
+		padding: 8px 12px;
+		border-radius: 4px;
+		box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
+		border: none;
+	}
+
+	.ant-popover-inner-content {
+		padding: 0;
+	}
+}
+
+.span-hover-card-content {
+	font-family: Inter, sans-serif;
+	font-size: 12px;
+	color: #fff;
+
+	&__name {
+		font-weight: 600;
+		margin-bottom: 4px;
+	}
+
+	&__row {
+		line-height: 1.5;
+	}
+}

frontend/src/pages/TraceDetailsV3/SpanHoverCard/SpanHoverCard.tsx

@@ -0,0 +1,94 @@
+import { ReactNode } from 'react';
+import { Popover } from 'antd';
+import { themeColors } from 'constants/theme';
+import { convertTimeToRelevantUnit } from 'container/TraceDetail/utils';
+import { generateColor } from 'lib/uPlotLib/utils/generateColor';
+import { Span } from 'types/api/trace/getTraceV2';
+import { toFixed } from 'utils/toFixed';
+
+import './SpanHoverCard.styles.scss';
+
+interface ITraceMetadata {
+	startTime: number;
+	endTime: number;
+}
+
+export interface SpanTooltipContentProps {
+	spanName: string;
+	color: string;
+	hasError: boolean;
+	relativeStartMs: number;
+	durationMs: number;
+}
+
+export function SpanTooltipContent({
+	spanName,
+	color,
+	hasError,
+	relativeStartMs,
+	durationMs,
+}: SpanTooltipContentProps): JSX.Element {
+	const { time: formattedDuration, timeUnitName } = convertTimeToRelevantUnit(
+		durationMs,
+	);
+
+	return (
+		<div className="span-hover-card-content">
+			<div className="span-hover-card-content__name" style={{ color }}>
+				{spanName}
+			</div>
+			<div className="span-hover-card-content__row">
+				Status: {hasError ? 'error' : 'ok'}
+			</div>
+			<div className="span-hover-card-content__row">
+				Start: {toFixed(relativeStartMs, 2)} ms
+			</div>
+			<div className="span-hover-card-content__row">
+				Duration: {toFixed(formattedDuration, 2)} {timeUnitName}
+			</div>
+		</div>
+	);
+}
+
+interface SpanHoverCardProps {
+	span: Span;
+	traceMetadata: ITraceMetadata;
+	children: ReactNode;
+}
+
+function SpanHoverCard({
+	span,
+	traceMetadata,
+	children,
+}: SpanHoverCardProps): JSX.Element {
+	const durationMs = span.durationNano / 1e6;
+	const relativeStartMs = span.timestamp - traceMetadata.startTime;
+
+	let color = generateColor(span.serviceName, themeColors.traceDetailColorsV3);
+	if (span.hasError) {
+		color = 'var(--bg-cherry-500)';
+	}
+
+	return (
+		<Popover
+			mouseEnterDelay={0.2}
+			content={
+				<SpanTooltipContent
+					spanName={span.name}
+					color={color}
+					hasError={span.hasError}
+					relativeStartMs={relativeStartMs}
+					durationMs={durationMs}
+				/>
+			}
+			trigger="hover"
+			rootClassName="span-hover-card-popover"
+			autoAdjustOverflow
+			arrow={false}
+		>
+			{children}
+		</Popover>
+	);
+}
+
+export default SpanHoverCard;

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/FlamegraphCanvas.tsx

@@ -0,0 +1,250 @@
+import React, { useCallback, useEffect, useRef, useState } from 'react';
+import { createPortal } from 'react-dom';
+import TimelineV3 from 'components/TimelineV3/TimelineV3';
+import { useIsDarkMode } from 'hooks/useDarkMode';
+
+import { EventTooltipContent } from '../SpanHoverCard/EventTooltipContent';
+import { SpanTooltipContent } from '../SpanHoverCard/SpanHoverCard';
+import { DEFAULT_ROW_HEIGHT } from './constants';
+import { useCanvasSetup } from './hooks/useCanvasSetup';
+import { useFlamegraphDrag } from './hooks/useFlamegraphDrag';
+import { useFlamegraphDraw } from './hooks/useFlamegraphDraw';
+import { useFlamegraphHover } from './hooks/useFlamegraphHover';
+import { useFlamegraphZoom } from './hooks/useFlamegraphZoom';
+import { useScrollToSpan } from './hooks/useScrollToSpan';
+import { useVisualLayoutWorker } from './hooks/useVisualLayoutWorker';
+import { EventRect, FlamegraphCanvasProps, SpanRect } from './types';
+
+function FlamegraphCanvas(props: FlamegraphCanvasProps): JSX.Element {
+	const { spans, traceMetadata, firstSpanAtFetchLevel, onSpanClick } = props;
+
+	const isDarkMode = useIsDarkMode(); //TODO: see if can be removed or use a new hook
+	const canvasRef = useRef<HTMLCanvasElement>(null);
+	const containerRef = useRef<HTMLDivElement>(null);
+	const spanRectsRef = useRef<SpanRect[]>([]);
+	const eventRectsRef = useRef<EventRect[]>([]);
+
+	const [viewStartTs, setViewStartTs] = useState<number>(
+		traceMetadata.startTime,
+	);
+	const [viewEndTs, setViewEndTs] = useState<number>(traceMetadata.endTime);
+	const [scrollTop, setScrollTop] = useState<number>(0);
+	const [rowHeight, setRowHeight] = useState<number>(DEFAULT_ROW_HEIGHT);
+
+	// Mutable refs for zoom and drag hooks to read during rAF / mouse callbacks
+	const viewStartRef = useRef(viewStartTs);
+	const viewEndRef = useRef(viewEndTs);
+	const rowHeightRef = useRef(rowHeight);
+	const scrollTopRef = useRef(scrollTop);
+
+	useEffect(() => {
+		viewStartRef.current = viewStartTs;
+	}, [viewStartTs]);
+
+	useEffect(() => {
+		viewEndRef.current = viewEndTs;
+	}, [viewEndTs]);
+
+	useEffect(() => {
+		rowHeightRef.current = rowHeight;
+	}, [rowHeight]);
+
+	useEffect(() => {
+		scrollTopRef.current = scrollTop;
+	}, [scrollTop]);
+
+	useEffect(() => {
+		//TODO: see if this can be removed as once loaded the view start and end ts will not change
+		setViewStartTs(traceMetadata.startTime);
+		setViewEndTs(traceMetadata.endTime);
+		viewStartRef.current = traceMetadata.startTime;
+		viewEndRef.current = traceMetadata.endTime;
+	}, [traceMetadata.startTime, traceMetadata.endTime]);
+
+	const { layout, isComputing: _isComputing } = useVisualLayoutWorker(spans);
+
+	const totalHeight = layout.totalVisualRows * rowHeight;
+
+	const { isOverFlamegraphRef } = useFlamegraphZoom({
+		canvasRef,
+		traceMetadata,
+		viewStartRef,
+		viewEndRef,
+		rowHeightRef,
+		setViewStartTs,
+		setViewEndTs,
+		setRowHeight,
+	});
+
+	const {
+		handleMouseDown,
+		handleMouseMove: handleDragMouseMove,
+		handleMouseUp,
+		handleDragMouseLeave,
+		isDraggingRef,
+	} = useFlamegraphDrag({
+		canvasRef,
+		containerRef,
+		traceMetadata,
+		viewStartRef,
+		viewEndRef,
+		setViewStartTs,
+		setViewEndTs,
+		scrollTopRef,
+		setScrollTop,
+		totalHeight,
+	});
+
+	const {
+		hoveredSpanId,
+		hoveredEventKey,
+		handleHoverMouseMove,
+		handleHoverMouseLeave,
+		handleMouseDownForClick,
+		handleClick,
+		tooltipContent,
+	} = useFlamegraphHover({
+		canvasRef,
+		spanRectsRef,
+		eventRectsRef,
+		traceMetadata,
+		viewStartTs,
+		viewEndTs,
+		isDraggingRef,
+		onSpanClick,
+		isDarkMode,
+	});
+
+	const { drawFlamegraph } = useFlamegraphDraw({
+		canvasRef,
+		containerRef,
+		spans: layout.visualRows,
+		connectors: layout.connectors,
+		viewStartTs,
+		viewEndTs,
+		scrollTop,
+		rowHeight,
+		selectedSpanId: firstSpanAtFetchLevel || undefined,
+		hoveredSpanId: hoveredSpanId ?? '',
+		isDarkMode,
+		spanRectsRef,
+		eventRectsRef,
+		hoveredEventKey,
+	});
+
+	useScrollToSpan({
+		firstSpanAtFetchLevel,
+		spans: layout.visualRows,
+		traceMetadata,
+		containerRef,
+		viewStartRef,
+		viewEndRef,
+		scrollTopRef,
+		rowHeight,
+		setViewStartTs,
+		setViewEndTs,
+		setScrollTop,
+	});
+
+	useCanvasSetup(canvasRef, containerRef, drawFlamegraph);
+
+	const handleMouseMove = useCallback(
+		(e: React.MouseEvent): void => {
+			handleDragMouseMove(e);
+			handleHoverMouseMove(e);
+		},
+		[handleDragMouseMove, handleHoverMouseMove],
+	);
+
+	const handleMouseLeave = useCallback((): void => {
+		isOverFlamegraphRef.current = false;
+		handleDragMouseLeave();
+		handleHoverMouseLeave();
+	}, [isOverFlamegraphRef, handleDragMouseLeave, handleHoverMouseLeave]);
+
+	const tooltipElement = tooltipContent
+		? createPortal(
+				<div
+					className="span-hover-card-popover"
+					style={{
+						position: 'fixed',
+						left: Math.min(tooltipContent.clientX + 15, window.innerWidth - 220),
+						top: Math.min(tooltipContent.clientY + 15, window.innerHeight - 100),
+						zIndex: 1000,
+						backgroundColor: 'rgba(30, 30, 30, 0.95)',
+						padding: '8px 12px',
+						borderRadius: 4,
+						boxShadow: '0 2px 8px rgba(0,0,0,0.3)',
+						pointerEvents: 'none',
+					}}
+				>
+					{tooltipContent.event ? (
+						<EventTooltipContent
+							eventName={tooltipContent.event.name}
+							timeOffsetMs={tooltipContent.event.timeOffsetMs}
+							isError={tooltipContent.event.isError}
+							attributeMap={tooltipContent.event.attributeMap}
+						/>
+					) : (
+						<SpanTooltipContent
+							spanName={tooltipContent.spanName}
+							color={tooltipContent.spanColor}
+							hasError={tooltipContent.status === 'error'}
+							relativeStartMs={tooltipContent.startMs}
+							durationMs={tooltipContent.durationMs}
+						/>
+					)}
+				</div>,
+				document.body,
+		  )
+		: null;
+
+	return (
+		<div
+			style={{
+				display: 'flex',
+				flexDirection: 'column',
+				height: '100%',
+				padding: '0 15px',
+			}}
+		>
+			{tooltipElement}
+			<TimelineV3
+				startTimestamp={viewStartTs}
+				endTimestamp={viewEndTs}
+				offsetTimestamp={viewStartTs - traceMetadata.startTime}
+				timelineHeight={10}
+			/>
+			<div
+				ref={containerRef}
+				style={{
+					flex: 1,
+					overflow: 'hidden',
+					position: 'relative',
+				}}
+				onMouseEnter={(): void => {
+					isOverFlamegraphRef.current = true;
+				}}
+				onMouseLeave={handleMouseLeave}
+			>
+				<canvas
+					ref={canvasRef}
+					style={{
+						display: 'block',
+						width: '100%',
+						cursor: 'grab',
+					}}
+					onMouseDown={(e): void => {
+						handleMouseDown(e);
+						handleMouseDownForClick(e);
+					}}
+					onMouseMove={handleMouseMove}
+					onMouseUp={handleMouseUp}
+					onClick={handleClick}
+				/>
+			</div>
+		</div>
+	);
+}
+
+export default FlamegraphCanvas;

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/TraceFlamegraph.tsx

@@ -0,0 +1,108 @@
+import { useCallback, useEffect, useMemo, useState } from 'react';
+import { useHistory, useLocation, useParams } from 'react-router-dom';
+import useGetTraceFlamegraph from 'hooks/trace/useGetTraceFlamegraph';
+import useUrlQuery from 'hooks/useUrlQuery';
+import { TraceDetailFlamegraphURLProps } from 'types/api/trace/getTraceFlamegraph';
+
+import FlamegraphCanvas from './FlamegraphCanvas';
+
+//TODO: analyse if this is needed or not and move to separate file if needed else delete this enum.
+enum TraceFlamegraphState {
+	LOADING = 'LOADING',
+	SUCCESS = 'SUCCESS',
+	NO_DATA = 'NO_DATA',
+	ERROR = 'ERROR',
+	FETCHING_WITH_OLD_DATA = 'FETCHING_WITH_OLD_DATA',
+}
+
+function TraceFlamegraph(): JSX.Element {
+	const { id: traceId } = useParams<TraceDetailFlamegraphURLProps>();
+	const urlQuery = useUrlQuery();
+	const history = useHistory();
+	const { search } = useLocation();
+	const [firstSpanAtFetchLevel, setFirstSpanAtFetchLevel] = useState<string>(
+		urlQuery.get('spanId') || '',
+	);
+
+	useEffect(() => {
+		setFirstSpanAtFetchLevel(urlQuery.get('spanId') || '');
+	}, [urlQuery]);
+
+	const handleSpanClick = useCallback(
+		(spanId: string): void => {
+			setFirstSpanAtFetchLevel(spanId);
+			const searchParams = new URLSearchParams(search);
+			//tood: use from query params constants
+			if (searchParams.get('spanId') !== spanId) {
+				searchParams.set('spanId', spanId);
+				history.replace({ search: searchParams.toString() });
+			}
+		},
+		[history, search],
+	);
+
+	const { data, isFetching, error } = useGetTraceFlamegraph({
+		traceId,
+		// selectedSpanId: firstSpanAtFetchLevel,
+		limit: 120000,
+	});
+
+	const flamegraphState = useMemo(() => {
+		if (isFetching) {
+			if (data?.payload?.spans && data.payload.spans.length > 0) {
+				return TraceFlamegraphState.FETCHING_WITH_OLD_DATA;
+			}
+			return TraceFlamegraphState.LOADING;
+		}
+		if (error) {
+			return TraceFlamegraphState.ERROR;
+		}
+		if (data?.payload?.spans && data.payload.spans.length === 0) {
+			return TraceFlamegraphState.NO_DATA;
+		}
+		return TraceFlamegraphState.SUCCESS;
+	}, [error, isFetching, data]);
+
+	const spans = useMemo(() => data?.payload?.spans || [], [
+		data?.payload?.spans,
+	]);
+
+	const content = useMemo(() => {
+		switch (flamegraphState) {
+			case TraceFlamegraphState.LOADING:
+				return <div>Loading...</div>;
+			case TraceFlamegraphState.ERROR:
+				return <div>Error loading flamegraph</div>;
+			case TraceFlamegraphState.NO_DATA:
+				return <div>No data found for trace {traceId}</div>;
+			case TraceFlamegraphState.SUCCESS:
+			case TraceFlamegraphState.FETCHING_WITH_OLD_DATA:
+				return (
+					<FlamegraphCanvas
+						spans={spans}
+						firstSpanAtFetchLevel={firstSpanAtFetchLevel}
+						setFirstSpanAtFetchLevel={setFirstSpanAtFetchLevel}
+						onSpanClick={handleSpanClick}
+						traceMetadata={{
+							startTime: data?.payload?.startTimestampMillis || 0,
+							endTime: data?.payload?.endTimestampMillis || 0,
+						}}
+					/>
+				);
+			default:
+				return <div>Fetching the trace...</div>;
+		}
+	}, [
+		data?.payload?.endTimestampMillis,
+		data?.payload?.startTimestampMillis,
+		firstSpanAtFetchLevel,
+		flamegraphState,
+		spans,
+		traceId,
+		handleSpanClick,
+	]);
+
+	return <>{content}</>;
+}
+
+export default TraceFlamegraph;

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/__tests__/computeVisualLayout.test.ts

@@ -0,0 +1,475 @@
+import { FlamegraphSpan } from 'types/api/trace/getTraceFlamegraph';
+
+import { computeVisualLayout } from '../computeVisualLayout';
+
+function makeSpan(
+	overrides: Partial<FlamegraphSpan> & {
+		spanId: string;
+		timestamp: number;
+		durationNano: number;
+	},
+): FlamegraphSpan {
+	return {
+		parentSpanId: '',
+		traceId: 'trace-1',
+		hasError: false,
+		serviceName: 'svc',
+		name: 'op',
+		level: 0,
+		event: [],
+		...overrides,
+	};
+}
+
+describe('computeVisualLayout', () => {
+	it('should handle empty input', () => {
+		const layout = computeVisualLayout([]);
+		expect(layout.totalVisualRows).toBe(0);
+		expect(layout.visualRows).toEqual([]);
+	});
+
+	it('should handle single root, no children — 1 visual row', () => {
+		const root = makeSpan({
+			spanId: 'root',
+			timestamp: 0,
+			durationNano: 100e6,
+		});
+		const layout = computeVisualLayout([[root]]);
+		expect(layout.totalVisualRows).toBe(1);
+		expect(layout.visualRows[0]).toEqual([root]);
+		expect(layout.spanToVisualRow['root']).toBe(0);
+	});
+
+	it('should keep non-overlapping siblings on the same row (compact)', () => {
+		const root = makeSpan({
+			spanId: 'root',
+			timestamp: 0,
+			durationNano: 500e6,
+		});
+		const a = makeSpan({
+			spanId: 'a',
+			parentSpanId: 'root',
+			timestamp: 0,
+			durationNano: 100e6,
+		});
+		const b = makeSpan({
+			spanId: 'b',
+			parentSpanId: 'root',
+			timestamp: 200,
+			durationNano: 100e6,
+		});
+		const c = makeSpan({
+			spanId: 'c',
+			parentSpanId: 'root',
+			timestamp: 400,
+			durationNano: 100e6,
+		});
+
+		const layout = computeVisualLayout([[root], [a, b, c]]);
+
+		// root on row 0, all children on row 1
+		expect(layout.totalVisualRows).toBe(2);
+		expect(layout.spanToVisualRow['root']).toBe(0);
+		expect(layout.spanToVisualRow['a']).toBe(1);
+		expect(layout.spanToVisualRow['b']).toBe(1);
+		expect(layout.spanToVisualRow['c']).toBe(1);
+	});
+
+	it('should pack non-overlapping siblings into shared lanes (greedy packing)', () => {
+		const root = makeSpan({
+			spanId: 'root',
+			timestamp: 0,
+			durationNano: 300e6,
+		});
+		// A and B overlap; C does not overlap with either
+		const a = makeSpan({
+			spanId: 'a',
+			parentSpanId: 'root',
+			timestamp: 0,
+			durationNano: 100e6, // ends at 100ms
+		});
+		const b = makeSpan({
+			spanId: 'b',
+			parentSpanId: 'root',
+			timestamp: 50,
+			durationNano: 100e6, // starts at 50ms < 100ms end of A → overlap → lane 1
+		});
+		const c = makeSpan({
+			spanId: 'c',
+			parentSpanId: 'root',
+			timestamp: 200,
+			durationNano: 100e6, // 200 >= 100, fits lane 0 with A
+		});
+
+		const layout = computeVisualLayout([[root], [a, b, c]]);
+
+		// root on row 0, C placed first (latest) → row 1, B doesn't overlap C → row 1, A overlaps B → row 2
+		expect(layout.totalVisualRows).toBe(3);
+		expect(layout.spanToVisualRow['root']).toBe(0);
+		expect(layout.spanToVisualRow['c']).toBe(1);
+		expect(layout.spanToVisualRow['b']).toBe(1);
+		expect(layout.spanToVisualRow['a']).toBe(2);
+	});
+
+	it('should handle full overlap — all siblings get own row', () => {
+		const root = makeSpan({
+			spanId: 'root',
+			timestamp: 0,
+			durationNano: 200e6,
+		});
+		const a = makeSpan({
+			spanId: 'a',
+			parentSpanId: 'root',
+			timestamp: 0,
+			durationNano: 200e6,
+		});
+		const b = makeSpan({
+			spanId: 'b',
+			parentSpanId: 'root',
+			timestamp: 0,
+			durationNano: 200e6,
+		});
+
+		const layout = computeVisualLayout([[root], [a, b]]);
+
+		expect(layout.totalVisualRows).toBe(3);
+		expect(layout.spanToVisualRow['a']).toBe(1);
+		expect(layout.spanToVisualRow['b']).toBe(2);
+	});
+
+	it('should stack children correctly below overlapping parents', () => {
+		const root = makeSpan({
+			spanId: 'root',
+			timestamp: 0,
+			durationNano: 300e6,
+		});
+		const a = makeSpan({
+			spanId: 'a',
+			parentSpanId: 'root',
+			timestamp: 0,
+			durationNano: 200e6,
+		});
+		const b = makeSpan({
+			spanId: 'b',
+			parentSpanId: 'root',
+			timestamp: 50,
+			durationNano: 200e6,
+		});
+		// Child of A
+		const childA = makeSpan({
+			spanId: 'childA',
+			parentSpanId: 'a',
+			timestamp: 10,
+			durationNano: 50e6,
+		});
+		// Child of B
+		const childB = makeSpan({
+			spanId: 'childB',
+			parentSpanId: 'b',
+			timestamp: 60,
+			durationNano: 50e6,
+		});
+
+		const layout = computeVisualLayout([[root], [a, b], [childA, childB]]);
+
+		// DFS processes b's subtree first (latest):
+		// root → row 0
+		// b → row 1 (parentRow 0 + 1)
+		// childB → row 2 (parentRow 1 + 1)
+		// a → try row 1 (parentRow 0 + 1), overlaps b → try row 2, overlaps childB → row 3
+		// childA → row 4 (parentRow 3 + 1)
+		expect(layout.spanToVisualRow['root']).toBe(0);
+		expect(layout.spanToVisualRow['b']).toBe(1);
+		expect(layout.spanToVisualRow['childB']).toBe(2);
+		expect(layout.spanToVisualRow['a']).toBe(3);
+		expect(layout.spanToVisualRow['childA']).toBe(4);
+		expect(layout.totalVisualRows).toBe(5);
+	});
+
+	it('should handle multiple roots as a sibling group', () => {
+		// Two overlapping roots
+		const r1 = makeSpan({
+			spanId: 'r1',
+			timestamp: 0,
+			durationNano: 100e6,
+		});
+		const r2 = makeSpan({
+			spanId: 'r2',
+			timestamp: 50,
+			durationNano: 100e6,
+		});
+
+		const layout = computeVisualLayout([[r1, r2]]);
+
+		expect(layout.spanToVisualRow['r1']).toBe(0);
+		expect(layout.spanToVisualRow['r2']).toBe(1);
+		expect(layout.totalVisualRows).toBe(2);
+	});
+
+	it('should produce compact layout for deep nesting without overlap', () => {
+		const root = makeSpan({
+			spanId: 'root',
+			timestamp: 0,
+			durationNano: 1000e6,
+		});
+		const child = makeSpan({
+			spanId: 'child',
+			parentSpanId: 'root',
+			timestamp: 10,
+			durationNano: 500e6,
+		});
+		const grandchild = makeSpan({
+			spanId: 'grandchild',
+			parentSpanId: 'child',
+			timestamp: 20,
+			durationNano: 200e6,
+		});
+
+		const layout = computeVisualLayout([[root], [child], [grandchild]]);
+
+		// No overlap at any level → visual rows == tree depth
+		expect(layout.totalVisualRows).toBe(3);
+		expect(layout.spanToVisualRow['root']).toBe(0);
+		expect(layout.spanToVisualRow['child']).toBe(1);
+		expect(layout.spanToVisualRow['grandchild']).toBe(2);
+	});
+
+	it('should pack many sequential siblings into 1 row (no diagonal staircase)', () => {
+		const root = makeSpan({
+			spanId: 'root',
+			timestamp: 0,
+			durationNano: 500e6,
+		});
+		// 6 sequential children — like checkoutservice/PlaceOrder scenario
+		const spans = [
+			makeSpan({
+				spanId: 's1',
+				parentSpanId: 'root',
+				timestamp: 3,
+				durationNano: 30e6,
+			}),
+			makeSpan({
+				spanId: 's2',
+				parentSpanId: 'root',
+				timestamp: 35,
+				durationNano: 4e6,
+			}),
+			makeSpan({
+				spanId: 's3',
+				parentSpanId: 'root',
+				timestamp: 39,
+				durationNano: 1e6,
+			}),
+			makeSpan({
+				spanId: 's4',
+				parentSpanId: 'root',
+				timestamp: 40,
+				durationNano: 4e6,
+			}),
+			makeSpan({
+				spanId: 's5',
+				parentSpanId: 'root',
+				timestamp: 44,
+				durationNano: 5e6,
+			}),
+			makeSpan({
+				spanId: 's6',
+				parentSpanId: 'root',
+				timestamp: 49,
+				durationNano: 1e6,
+			}),
+		];
+
+		const layout = computeVisualLayout([[root], spans]);
+
+		// All 6 sequential siblings should share 1 row
+		expect(layout.totalVisualRows).toBe(2);
+		expect(layout.spanToVisualRow['root']).toBe(0);
+		for (const span of spans) {
+			expect(layout.spanToVisualRow[span.spanId]).toBe(1);
+		}
+	});
+
+	it('should keep children below parents even with misparented spans', () => {
+		// Simulates the dd_sig2 bug: /route spans have parentSpanId pointing
+		// to the wrong ancestor, but they are at level 2 in the spans[][] input.
+		// Level-based packing must place them below level 1 regardless.
+		const httpGet = makeSpan({
+			spanId: 'http-get',
+			timestamp: 0,
+			durationNano: 500e6,
+		});
+		const route = makeSpan({
+			spanId: 'route',
+			parentSpanId: 'some-wrong-ancestor', // misparented!
+			timestamp: 10,
+			durationNano: 200e6,
+		});
+
+		const layout = computeVisualLayout([[httpGet], [route]]);
+
+		// httpGet at level 0 → row 0, route at level 1 → row 1
+		expect(layout.spanToVisualRow['http-get']).toBe(0);
+		expect(layout.spanToVisualRow['route']).toBe(1);
+		expect(layout.totalVisualRows).toBe(2);
+	});
+
+	it('should keep parent-child pairs adjacent when sibling subtrees overlap', () => {
+		// Multiple overlapping parents each with a child — the subtree-unit
+		// guarantee means every parent→child gap should be exactly 1.
+		const root = makeSpan({
+			spanId: 'root',
+			timestamp: 0,
+			durationNano: 500e6,
+		});
+		// Three overlapping HTTP GET children of root, each with its own /route child
+		const get1 = makeSpan({
+			spanId: 'get1',
+			parentSpanId: 'root',
+			timestamp: 0,
+			durationNano: 200e6,
+		});
+		const route1 = makeSpan({
+			spanId: 'route1',
+			parentSpanId: 'get1',
+			timestamp: 10,
+			durationNano: 180e6,
+		});
+		const get2 = makeSpan({
+			spanId: 'get2',
+			parentSpanId: 'root',
+			timestamp: 50,
+			durationNano: 200e6,
+		});
+		const route2 = makeSpan({
+			spanId: 'route2',
+			parentSpanId: 'get2',
+			timestamp: 60,
+			durationNano: 180e6,
+		});
+		const get3 = makeSpan({
+			spanId: 'get3',
+			parentSpanId: 'root',
+			timestamp: 100,
+			durationNano: 200e6,
+		});
+		const route3 = makeSpan({
+			spanId: 'route3',
+			parentSpanId: 'get3',
+			timestamp: 110,
+			durationNano: 180e6,
+		});
+
+		const layout = computeVisualLayout([
+			[root],
+			[get1, get2, get3],
+			[route1, route2, route3],
+		]);
+
+		// Each parent-child pair should have a gap of exactly 1
+		const get1Row = layout.spanToVisualRow['get1'];
+		const route1Row = layout.spanToVisualRow['route1'];
+		const get2Row = layout.spanToVisualRow['get2'];
+		const route2Row = layout.spanToVisualRow['route2'];
+		const get3Row = layout.spanToVisualRow['get3'];
+		const route3Row = layout.spanToVisualRow['route3'];
+
+		expect(route1Row - get1Row).toBe(1);
+		expect(route2Row - get2Row).toBe(1);
+		expect(route3Row - get3Row).toBe(1);
+	});
+
+	it('should handle mixed levels — overlap at level 2 but not level 1', () => {
+		const root = makeSpan({
+			spanId: 'root',
+			timestamp: 0,
+			durationNano: 1000e6,
+		});
+		// Non-overlapping children
+		const a = makeSpan({
+			spanId: 'a',
+			parentSpanId: 'root',
+			timestamp: 0,
+			durationNano: 400e6,
+		});
+		const b = makeSpan({
+			spanId: 'b',
+			parentSpanId: 'root',
+			timestamp: 500,
+			durationNano: 400e6,
+		});
+		// Overlapping grandchildren under A
+		const ga1 = makeSpan({
+			spanId: 'ga1',
+			parentSpanId: 'a',
+			timestamp: 0,
+			durationNano: 200e6,
+		});
+		const ga2 = makeSpan({
+			spanId: 'ga2',
+			parentSpanId: 'a',
+			timestamp: 100,
+			durationNano: 200e6,
+		});
+
+		const layout = computeVisualLayout([[root], [a, b], [ga1, ga2]]);
+
+		// root → row 0
+		// a, b → row 1 (no overlap, share row)
+		// ga1 → row 2, ga2 → row 3 (overlap, expanded)
+		// b has no children, so nothing after ga2
+		expect(layout.spanToVisualRow['root']).toBe(0);
+		expect(layout.spanToVisualRow['a']).toBe(1);
+		expect(layout.spanToVisualRow['b']).toBe(1);
+		expect(layout.spanToVisualRow['ga2']).toBe(2);
+		expect(layout.spanToVisualRow['ga1']).toBe(3);
+		expect(layout.totalVisualRows).toBe(4);
+	});
+
+	it('should not place a span where it covers an existing connector point (Check 2)', () => {
+		// Scenario: root has 3 leaf children. Sorted latest-first: C(200), B(100), A(80).
+		//
+		// C placed at row 1 [200, 400].
+		// B overlaps C → placed at row 2 [100, 300]. Connector from row 0→2 at x=100
+		//   passes through row 1, recording connector point at (row 1, x=100).
+		// A [80, 110] does NOT overlap C's span [200, 400] at row 1 (110 < 200),
+		//   so without connector reservation A would fit at row 1.
+		//   But A's span [80, 110) contains the connector point x=100 at row 1.
+		//   Check 2 prevents this placement, pushing A further down.
+		const root = makeSpan({
+			spanId: 'root',
+			timestamp: 0,
+			durationNano: 500e6,
+		});
+		const c = makeSpan({
+			spanId: 'c',
+			parentSpanId: 'root',
+			timestamp: 200,
+			durationNano: 200e6, // [200, 400]
+		});
+		const b = makeSpan({
+			spanId: 'b',
+			parentSpanId: 'root',
+			timestamp: 100,
+			durationNano: 200e6, // [100, 300]
+		});
+		const a = makeSpan({
+			spanId: 'a',
+			parentSpanId: 'root',
+			timestamp: 80,
+			durationNano: 30e6, // [80, 110]
+		});
+
+		const layout = computeVisualLayout([[root], [a, b, c]]);
+
+		expect(layout.spanToVisualRow['root']).toBe(0);
+		expect(layout.spanToVisualRow['c']).toBe(1); // latest, placed first
+		expect(layout.spanToVisualRow['b']).toBe(2); // overlaps C → row 2
+
+		// A would fit at row 1 by span overlap alone, but connector point at
+		// (row 1, x=100) falls within A's span [80, 110). Check 2 pushes A down.
+		const aRow = layout.spanToVisualRow['a']!;
+		expect(aRow).toBeGreaterThan(1); // must NOT be at row 1
+		expect(aRow).toBe(3); // next free row after B at row 2 (A overlaps B)
+	});
+});

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/__tests__/drawUtils.test.ts

@@ -0,0 +1,539 @@
+import { DASHED_BORDER_LINE_DASH, MIN_WIDTH_FOR_NAME } from '../constants';
+import type { FlamegraphRowMetrics } from '../utils';
+import { getFlamegraphRowMetrics } from '../utils';
+import { drawEventDot, drawSpanBar, getEventDotColor } from '../utils';
+import { MOCK_SPAN } from './testUtils';
+
+jest.mock('container/TraceDetail/utils', () => ({
+	convertTimeToRelevantUnit: (): { time: number; timeUnitName: string } => ({
+		time: 50,
+		timeUnitName: 'ms',
+	}),
+}));
+
+/** Minimal 2D context for createStripePattern's internal canvas (jsdom getContext often returns null) */
+const mockPatternCanvasCtx = {
+	beginPath: jest.fn(),
+	moveTo: jest.fn(),
+	lineTo: jest.fn(),
+	stroke: jest.fn(),
+	globalAlpha: 1,
+};
+
+const originalCreateElement = document.createElement.bind(document);
+document.createElement = function (
+	tagName: string,
+): ReturnType<typeof originalCreateElement> {
+	const el = originalCreateElement(tagName);
+	if (tagName.toLowerCase() === 'canvas') {
+		(el as HTMLCanvasElement).getContext = (() =>
+			mockPatternCanvasCtx as unknown) as HTMLCanvasElement['getContext'];
+	}
+	return el;
+};
+
+function createMockCtx(): jest.Mocked<CanvasRenderingContext2D> {
+	return ({
+		beginPath: jest.fn(),
+		roundRect: jest.fn(),
+		fill: jest.fn(),
+		stroke: jest.fn(),
+		save: jest.fn(),
+		restore: jest.fn(),
+		translate: jest.fn(),
+		rotate: jest.fn(),
+		fillRect: jest.fn(),
+		strokeRect: jest.fn(),
+		setLineDash: jest.fn(),
+		measureText: jest.fn(
+			(text: string) => ({ width: text.length * 6 } as TextMetrics),
+		),
+		createPattern: jest.fn(() => ({} as CanvasPattern)),
+		clip: jest.fn(),
+		rect: jest.fn(),
+		fillText: jest.fn(),
+		font: '',
+		fillStyle: '',
+		strokeStyle: '',
+		textAlign: '',
+		textBaseline: '',
+		lineWidth: 0,
+		globalAlpha: 1,
+	} as unknown) as jest.Mocked<CanvasRenderingContext2D>;
+}
+
+const METRICS: FlamegraphRowMetrics = getFlamegraphRowMetrics(24);
+
+describe('Canvas Draw Utils', () => {
+	describe('drawSpanBar', () => {
+		it('draws rect + fill for normal span (no selected/hovered)', () => {
+			const ctx = createMockCtx();
+			const spanRectsArray: {
+				span: typeof MOCK_SPAN;
+				x: number;
+				y: number;
+				width: number;
+				height: number;
+				level: number;
+			}[] = [];
+
+			drawSpanBar({
+				ctx,
+				span: { ...MOCK_SPAN, event: [] },
+				x: 10,
+				y: 0,
+				width: 100,
+				levelIndex: 0,
+				spanRectsArray,
+				eventRectsArray: [],
+				color: '#1890ff',
+				isDarkMode: false,
+				metrics: METRICS,
+			});
+
+			expect(ctx.beginPath).toHaveBeenCalled();
+			expect(ctx.roundRect).toHaveBeenCalledWith(10, 1, 100, 22, 2);
+			expect(ctx.fill).toHaveBeenCalled();
+			expect(ctx.stroke).not.toHaveBeenCalled();
+			expect(spanRectsArray).toHaveLength(1);
+			expect(spanRectsArray[0]).toMatchObject({
+				x: 10,
+				y: 1,
+				width: 100,
+				height: 22,
+				level: 0,
+			});
+		});
+
+		it('uses stripe pattern + dashed stroke + 2px when selected', () => {
+			const ctx = createMockCtx();
+			const spanRectsArray: {
+				span: typeof MOCK_SPAN;
+				x: number;
+				y: number;
+				width: number;
+				height: number;
+				level: number;
+			}[] = [];
+
+			drawSpanBar({
+				ctx,
+				span: { ...MOCK_SPAN, spanId: 'sel', event: [] },
+				x: 20,
+				y: 0,
+				width: 80,
+				levelIndex: 1,
+				spanRectsArray,
+				eventRectsArray: [],
+				color: '#2F80ED',
+				isDarkMode: false,
+				metrics: METRICS,
+				selectedSpanId: 'sel',
+			});
+
+			expect(ctx.createPattern).toHaveBeenCalled();
+			expect(ctx.setLineDash).toHaveBeenCalledWith(DASHED_BORDER_LINE_DASH);
+			expect(ctx.strokeStyle).toBe('#2F80ED');
+			expect(ctx.lineWidth).toBe(2);
+			expect(ctx.stroke).toHaveBeenCalled();
+			expect(ctx.setLineDash).toHaveBeenLastCalledWith([]);
+		});
+
+		it('uses stripe pattern + solid stroke + 1px when hovered (not selected)', () => {
+			const ctx = createMockCtx();
+			const spanRectsArray: {
+				span: typeof MOCK_SPAN;
+				x: number;
+				y: number;
+				width: number;
+				height: number;
+				level: number;
+			}[] = [];
+
+			drawSpanBar({
+				ctx,
+				span: { ...MOCK_SPAN, spanId: 'hov', event: [] },
+				x: 30,
+				y: 0,
+				width: 60,
+				levelIndex: 0,
+				spanRectsArray,
+				eventRectsArray: [],
+				color: '#2F80ED',
+				isDarkMode: false,
+				metrics: METRICS,
+				hoveredSpanId: 'hov',
+			});
+
+			expect(ctx.createPattern).toHaveBeenCalled();
+			expect(ctx.setLineDash).not.toHaveBeenCalled();
+			expect(ctx.lineWidth).toBe(1);
+			expect(ctx.stroke).toHaveBeenCalled();
+		});
+
+		it('pushes spanRectsArray with correct dimensions', () => {
+			const ctx = createMockCtx();
+			const spanRectsArray: {
+				span: typeof MOCK_SPAN;
+				x: number;
+				y: number;
+				width: number;
+				height: number;
+				level: number;
+			}[] = [];
+
+			drawSpanBar({
+				ctx,
+				span: { ...MOCK_SPAN, spanId: 'rect-test', event: [] },
+				x: 5,
+				y: 24,
+				width: 200,
+				levelIndex: 2,
+				spanRectsArray,
+				eventRectsArray: [],
+				color: '#000',
+				isDarkMode: false,
+				metrics: METRICS,
+			});
+
+			expect(spanRectsArray[0]).toMatchObject({
+				x: 5,
+				y: 25,
+				width: 200,
+				height: 22,
+				level: 2,
+			});
+			expect(spanRectsArray[0].span.spanId).toBe('rect-test');
+		});
+	});
+
+	describe('drawSpanLabel (via drawSpanBar)', () => {
+		it('skips label when width < MIN_WIDTH_FOR_NAME', () => {
+			const ctx = createMockCtx();
+			const spanRectsArray: {
+				span: typeof MOCK_SPAN;
+				x: number;
+				y: number;
+				width: number;
+				height: number;
+				level: number;
+			}[] = [];
+
+			drawSpanBar({
+				ctx,
+				span: { ...MOCK_SPAN, name: 'long-span-name', event: [] },
+				x: 0,
+				y: 0,
+				width: MIN_WIDTH_FOR_NAME - 1,
+				levelIndex: 0,
+				spanRectsArray,
+				eventRectsArray: [],
+				color: '#000',
+				isDarkMode: false,
+				metrics: METRICS,
+			});
+
+			expect(ctx.clip).not.toHaveBeenCalled();
+			expect(ctx.fillText).not.toHaveBeenCalled();
+		});
+
+		it('draws name only when width >= MIN_WIDTH_FOR_NAME but < MIN_WIDTH_FOR_NAME_AND_DURATION', () => {
+			const ctx = createMockCtx();
+			ctx.measureText = jest.fn(
+				(t: string) => ({ width: t.length * 6 } as TextMetrics),
+			);
+
+			drawSpanBar({
+				ctx,
+				span: { ...MOCK_SPAN, name: 'foo', event: [] },
+				x: 0,
+				y: 0,
+				width: 50,
+				levelIndex: 0,
+				spanRectsArray: [],
+				eventRectsArray: [],
+				color: '#000',
+				isDarkMode: false,
+				metrics: METRICS,
+			});
+
+			expect(ctx.clip).toHaveBeenCalled();
+			expect(ctx.fillText).toHaveBeenCalled();
+			expect(ctx.textAlign).toBe('left');
+		});
+
+		it('draws name + duration when width >= MIN_WIDTH_FOR_NAME_AND_DURATION', () => {
+			const ctx = createMockCtx();
+			ctx.measureText = jest.fn(
+				(t: string) => ({ width: t.length * 6 } as TextMetrics),
+			);
+
+			drawSpanBar({
+				ctx,
+				span: { ...MOCK_SPAN, name: 'my-span', event: [] },
+				x: 0,
+				y: 0,
+				width: 100,
+				levelIndex: 0,
+				spanRectsArray: [],
+				eventRectsArray: [],
+				color: '#000',
+				isDarkMode: false,
+				metrics: METRICS,
+			});
+
+			expect(ctx.fillText).toHaveBeenCalledTimes(2);
+			expect(ctx.fillText).toHaveBeenCalledWith(
+				'50ms',
+				expect.any(Number),
+				expect.any(Number),
+			);
+			expect(ctx.fillText).toHaveBeenCalledWith(
+				'my-span',
+				expect.any(Number),
+				expect.any(Number),
+			);
+		});
+	});
+
+	describe('truncateText (via drawSpanBar)', () => {
+		it('uses full text when it fits', () => {
+			const ctx = createMockCtx();
+			ctx.measureText = jest.fn(
+				(t: string) => ({ width: t.length * 4 } as TextMetrics),
+			);
+
+			drawSpanBar({
+				ctx,
+				span: { ...MOCK_SPAN, name: 'short', event: [] },
+				x: 0,
+				y: 0,
+				width: 100,
+				levelIndex: 0,
+				spanRectsArray: [],
+				eventRectsArray: [],
+				color: '#000',
+				isDarkMode: false,
+				metrics: METRICS,
+			});
+
+			expect(ctx.fillText).toHaveBeenCalledWith(
+				'short',
+				expect.any(Number),
+				expect.any(Number),
+			);
+		});
+
+		it('truncates text when it exceeds available width', () => {
+			const ctx = createMockCtx();
+			ctx.measureText = jest.fn(
+				(t: string) =>
+					({
+						width: t.includes('...') ? 24 : t.length * 10,
+					} as TextMetrics),
+			);
+
+			drawSpanBar({
+				ctx,
+				span: { ...MOCK_SPAN, name: 'very-long-span-name', event: [] },
+				x: 0,
+				y: 0,
+				width: 50,
+				levelIndex: 0,
+				spanRectsArray: [],
+				eventRectsArray: [],
+				color: '#000',
+				isDarkMode: false,
+				metrics: METRICS,
+			});
+
+			const fillTextCalls = (ctx.fillText as jest.Mock).mock.calls;
+			const nameArg = fillTextCalls.find((c) => c[0] !== '50ms')?.[0];
+			expect(nameArg).toBeDefined();
+			expect(nameArg).toMatch(/\.\.\.$/);
+		});
+	});
+
+	describe('drawEventDot', () => {
+		it('uses error styling when isError is true', () => {
+			const ctx = createMockCtx();
+			const color = getEventDotColor('#000', true, false);
+
+			drawEventDot({
+				ctx,
+				x: 50,
+				y: 11,
+				color,
+				eventDotSize: 6,
+			});
+
+			expect(ctx.save).toHaveBeenCalled();
+			expect(ctx.translate).toHaveBeenCalledWith(50, 11);
+			expect(ctx.rotate).toHaveBeenCalledWith(Math.PI / 4);
+			expect(ctx.fillStyle).toBe('rgb(220, 38, 38)');
+			expect(ctx.strokeStyle).toBe('rgb(153, 27, 27)');
+			expect(ctx.fillRect).toHaveBeenCalledWith(-3, -3, 6, 6);
+			expect(ctx.strokeRect).toHaveBeenCalledWith(-3, -3, 6, 6);
+			expect(ctx.restore).toHaveBeenCalled();
+		});
+
+		it('derives color from span color when isError is false', () => {
+			const ctx = createMockCtx();
+			const color = getEventDotColor('rgb(100, 200, 150)', false, false);
+
+			drawEventDot({
+				ctx,
+				x: 0,
+				y: 0,
+				color,
+				eventDotSize: 6,
+			});
+
+			// Darkened by 20% for fill
+			expect(ctx.fillStyle).toBe('rgb(80, 160, 120)');
+			// Darkened by 40% for stroke
+			expect(ctx.strokeStyle).toBe('rgb(60, 120, 90)');
+		});
+
+		it('uses dark mode colors for error', () => {
+			const ctx = createMockCtx();
+			const color = getEventDotColor('#000', true, true);
+
+			drawEventDot({
+				ctx,
+				x: 0,
+				y: 0,
+				color,
+				eventDotSize: 6,
+			});
+
+			expect(ctx.fillStyle).toBe('rgb(239, 68, 68)');
+			expect(ctx.strokeStyle).toBe('rgb(185, 28, 28)');
+		});
+
+		it('falls back to cyan/blue for unparseable span colors', () => {
+			const ctx = createMockCtx();
+			const color = getEventDotColor('hsl(200, 50%, 50%)', false, false);
+
+			drawEventDot({
+				ctx,
+				x: 0,
+				y: 0,
+				color,
+				eventDotSize: 6,
+			});
+
+			expect(ctx.fillStyle).toBe('rgb(6, 182, 212)');
+			expect(ctx.strokeStyle).toBe('rgb(8, 145, 178)');
+		});
+
+		it('calls save, translate, rotate, restore', () => {
+			const ctx = createMockCtx();
+			const color = getEventDotColor('#000', false, false);
+
+			drawEventDot({
+				ctx,
+				x: 10,
+				y: 20,
+				color,
+				eventDotSize: 4,
+			});
+
+			expect(ctx.save).toHaveBeenCalled();
+			expect(ctx.translate).toHaveBeenCalledWith(10, 20);
+			expect(ctx.rotate).toHaveBeenCalledWith(Math.PI / 4);
+			expect(ctx.restore).toHaveBeenCalled();
+		});
+	});
+
+	describe('createStripePattern (via drawSpanBar)', () => {
+		it('uses pattern when createPattern returns non-null', () => {
+			const ctx = createMockCtx();
+			const mockPattern = {} as CanvasPattern;
+			(ctx.createPattern as jest.Mock).mockReturnValue(mockPattern);
+
+			drawSpanBar({
+				ctx,
+				span: { ...MOCK_SPAN, spanId: 'p', event: [] },
+				x: 0,
+				y: 0,
+				width: MIN_WIDTH_FOR_NAME - 1,
+				levelIndex: 0,
+				spanRectsArray: [],
+				eventRectsArray: [],
+				color: '#000',
+				isDarkMode: false,
+				metrics: METRICS,
+				hoveredSpanId: 'p',
+			});
+
+			expect(ctx.createPattern).toHaveBeenCalled();
+			expect(ctx.fillStyle).toBe(mockPattern);
+			expect(ctx.fill).toHaveBeenCalled();
+		});
+
+		it('skips fill when createPattern returns null', () => {
+			const ctx = createMockCtx();
+			(ctx.createPattern as jest.Mock).mockReturnValue(null);
+
+			drawSpanBar({
+				ctx,
+				span: { ...MOCK_SPAN, spanId: 'p', event: [] },
+				x: 0,
+				y: 0,
+				width: MIN_WIDTH_FOR_NAME - 1,
+				levelIndex: 0,
+				spanRectsArray: [],
+				eventRectsArray: [],
+				color: '#000',
+				isDarkMode: false,
+				metrics: METRICS,
+				selectedSpanId: 'p',
+			});
+
+			expect(ctx.fill).not.toHaveBeenCalled();
+			expect(ctx.stroke).toHaveBeenCalled();
+		});
+	});
+
+	describe('drawSpanBar with events', () => {
+		it('draws event dots for each span event', () => {
+			const ctx = createMockCtx();
+			const spanWithEvents = {
+				...MOCK_SPAN,
+				event: [
+					{
+						name: 'e1',
+						timeUnixNano: 1_010_000_000,
+						attributeMap: {},
+						isError: false,
+					},
+					{
+						name: 'e2',
+						timeUnixNano: 1_025_000_000,
+						attributeMap: {},
+						isError: true,
+					},
+				],
+			};
+
+			drawSpanBar({
+				ctx,
+				span: spanWithEvents,
+				x: 0,
+				y: 0,
+				width: 100,
+				levelIndex: 0,
+				spanRectsArray: [],
+				eventRectsArray: [],
+				color: '#000',
+				isDarkMode: false,
+				metrics: METRICS,
+			});
+
+			expect(ctx.save).toHaveBeenCalledTimes(3);
+			expect(ctx.translate).toHaveBeenCalledTimes(2);
+			expect(ctx.fillRect).toHaveBeenCalledTimes(2);
+		});
+	});
+});

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/__tests__/testUtils.ts

@@ -0,0 +1,54 @@
+import { FlamegraphSpan } from 'types/api/trace/getTraceFlamegraph';
+
+/** Minimal FlamegraphSpan for unit tests */
+export const MOCK_SPAN: FlamegraphSpan = {
+	timestamp: 1000,
+	durationNano: 50_000_000, // 50ms
+	spanId: 'span-1',
+	parentSpanId: '',
+	traceId: 'trace-1',
+	hasError: false,
+	serviceName: 'test-service',
+	name: 'test-span',
+	level: 0,
+	event: [],
+};
+
+/** Nested spans structure for findSpanById tests */
+export const MOCK_SPANS: FlamegraphSpan[][] = [
+	[
+		{
+			...MOCK_SPAN,
+			spanId: 'root',
+			parentSpanId: '',
+			level: 0,
+		},
+	],
+	[
+		{
+			...MOCK_SPAN,
+			spanId: 'child-a',
+			parentSpanId: 'root',
+			level: 1,
+		},
+		{
+			...MOCK_SPAN,
+			spanId: 'child-b',
+			parentSpanId: 'root',
+			level: 1,
+		},
+	],
+	[
+		{
+			...MOCK_SPAN,
+			spanId: 'grandchild',
+			parentSpanId: 'child-a',
+			level: 2,
+		},
+	],
+];
+
+export const MOCK_TRACE_METADATA = {
+	startTime: 0,
+	endTime: 1000,
+};

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/__tests__/useFlamegraphDrag.test.ts

@@ -0,0 +1,144 @@
+import React from 'react';
+import { act, renderHook } from '@testing-library/react';
+
+import { useFlamegraphDrag } from '../hooks/useFlamegraphDrag';
+import { MOCK_TRACE_METADATA } from './testUtils';
+
+function createMockCanvas(): HTMLCanvasElement {
+	const canvas = document.createElement('canvas');
+	canvas.getBoundingClientRect = jest.fn(
+		(): DOMRect =>
+			({
+				left: 0,
+				top: 0,
+				width: 800,
+				height: 400,
+				x: 0,
+				y: 0,
+				bottom: 400,
+				right: 800,
+				toJSON: (): Record<string, unknown> => ({}),
+			} as DOMRect),
+	);
+	return canvas;
+}
+
+function createMockContainer(): HTMLDivElement {
+	const div = document.createElement('div');
+	Object.defineProperty(div, 'clientHeight', { value: 400 });
+	return div;
+}
+
+const defaultArgs = {
+	canvasRef: { current: createMockCanvas() },
+	containerRef: { current: createMockContainer() },
+	traceMetadata: MOCK_TRACE_METADATA,
+	viewStartRef: { current: 0 },
+	viewEndRef: { current: 1000 },
+	setViewStartTs: jest.fn(),
+	setViewEndTs: jest.fn(),
+	scrollTopRef: { current: 0 },
+	setScrollTop: jest.fn(),
+	totalHeight: 1000,
+};
+
+describe('useFlamegraphDrag', () => {
+	beforeEach(() => {
+		jest.clearAllMocks();
+		defaultArgs.viewStartRef.current = 0;
+		defaultArgs.viewEndRef.current = 1000;
+		defaultArgs.scrollTopRef.current = 0;
+	});
+
+	it('starts drag state on mousedown', () => {
+		const { result } = renderHook(() => useFlamegraphDrag(defaultArgs));
+
+		act(() => {
+			result.current.handleMouseDown(({
+				button: 0,
+				clientX: 100,
+				clientY: 50,
+				preventDefault: jest.fn(),
+			} as unknown) as React.MouseEvent);
+		});
+
+		expect(result.current.isDraggingRef.current).toBe(true);
+	});
+
+	it('ignores non-left button mousedown', () => {
+		const { result } = renderHook(() => useFlamegraphDrag(defaultArgs));
+
+		act(() => {
+			result.current.handleMouseDown(({
+				button: 1,
+				clientX: 100,
+				clientY: 50,
+				preventDefault: jest.fn(),
+			} as unknown) as React.MouseEvent);
+		});
+
+		expect(result.current.isDraggingRef.current).toBe(false);
+	});
+
+	it('updates pan/scroll on mousemove', () => {
+		const { result } = renderHook(() => useFlamegraphDrag(defaultArgs));
+
+		act(() => {
+			result.current.handleMouseDown(({
+				button: 0,
+				clientX: 100,
+				clientY: 50,
+				preventDefault: jest.fn(),
+			} as unknown) as React.MouseEvent);
+		});
+
+		act(() => {
+			result.current.handleMouseMove(({
+				clientX: 150,
+				clientY: 100,
+			} as unknown) as React.MouseEvent);
+		});
+
+		expect(defaultArgs.setViewStartTs).toHaveBeenCalled();
+		expect(defaultArgs.setViewEndTs).toHaveBeenCalled();
+		expect(defaultArgs.setScrollTop).toHaveBeenCalled();
+	});
+
+	it('resets drag state on mouseup', () => {
+		const { result } = renderHook(() => useFlamegraphDrag(defaultArgs));
+
+		act(() => {
+			result.current.handleMouseDown(({
+				button: 0,
+				clientX: 100,
+				clientY: 50,
+				preventDefault: jest.fn(),
+			} as unknown) as React.MouseEvent);
+		});
+
+		act(() => {
+			result.current.handleMouseUp();
+		});
+
+		expect(result.current.isDraggingRef.current).toBe(false);
+	});
+
+	it('cancels drag on mouseleave', () => {
+		const { result } = renderHook(() => useFlamegraphDrag(defaultArgs));
+
+		act(() => {
+			result.current.handleMouseDown(({
+				button: 0,
+				clientX: 100,
+				clientY: 50,
+				preventDefault: jest.fn(),
+			} as unknown) as React.MouseEvent);
+		});
+
+		act(() => {
+			result.current.handleDragMouseLeave();
+		});
+
+		expect(result.current.isDraggingRef.current).toBe(false);
+	});
+});

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/__tests__/useFlamegraphHover.test.ts

@@ -0,0 +1,179 @@
+import type React from 'react';
+import { act, renderHook } from '@testing-library/react';
+
+import { useFlamegraphHover } from '../hooks/useFlamegraphHover';
+import type { SpanRect } from '../types';
+import { MOCK_SPAN, MOCK_TRACE_METADATA } from './testUtils';
+
+function createMockCanvas(): HTMLCanvasElement {
+	const canvas = document.createElement('canvas');
+	canvas.width = 800;
+	canvas.height = 400;
+	canvas.getBoundingClientRect = jest.fn(
+		(): DOMRect =>
+			({
+				left: 0,
+				top: 0,
+				width: 800,
+				height: 400,
+				x: 0,
+				y: 0,
+				bottom: 400,
+				right: 800,
+				toJSON: (): Record<string, unknown> => ({}),
+			} as DOMRect),
+	);
+	return canvas;
+}
+
+const spanRect: SpanRect = {
+	span: { ...MOCK_SPAN, spanId: 'hover-span', name: 'test-span' },
+	x: 100,
+	y: 50,
+	width: 200,
+	height: 22,
+	level: 0,
+};
+
+const defaultArgs = {
+	canvasRef: { current: createMockCanvas() },
+	spanRectsRef: { current: [spanRect] },
+	eventRectsRef: { current: [] as any[] },
+	traceMetadata: MOCK_TRACE_METADATA,
+	viewStartTs: MOCK_TRACE_METADATA.startTime,
+	viewEndTs: MOCK_TRACE_METADATA.endTime,
+	isDraggingRef: { current: false },
+	onSpanClick: jest.fn(),
+	isDarkMode: false,
+};
+
+describe('useFlamegraphHover', () => {
+	beforeEach(() => {
+		Object.defineProperty(window, 'devicePixelRatio', {
+			configurable: true,
+			value: 1,
+		});
+		jest.clearAllMocks();
+		defaultArgs.spanRectsRef.current = [spanRect];
+		defaultArgs.isDraggingRef.current = false;
+	});
+
+	it('sets hoveredSpanId and tooltipContent when hovering on span', () => {
+		const { result } = renderHook(() => useFlamegraphHover(defaultArgs));
+
+		act(() => {
+			result.current.handleHoverMouseMove({
+				clientX: 150,
+				clientY: 61,
+			} as React.MouseEvent);
+		});
+
+		expect(result.current.hoveredSpanId).toBe('hover-span');
+		expect(result.current.tooltipContent).not.toBeNull();
+		expect(result.current.tooltipContent?.spanName).toBe('test-span');
+		expect(result.current.tooltipContent?.clientX).toBe(150);
+		expect(result.current.tooltipContent?.clientY).toBe(61);
+	});
+
+	it('clears hover when moving to empty area', () => {
+		const { result } = renderHook(() => useFlamegraphHover(defaultArgs));
+
+		act(() => {
+			result.current.handleHoverMouseMove({
+				clientX: 150,
+				clientY: 61,
+			} as React.MouseEvent);
+		});
+
+		expect(result.current.hoveredSpanId).toBe('hover-span');
+
+		act(() => {
+			result.current.handleHoverMouseMove({
+				clientX: 10,
+				clientY: 10,
+			} as React.MouseEvent);
+		});
+
+		expect(result.current.hoveredSpanId).toBeNull();
+		expect(result.current.tooltipContent).toBeNull();
+	});
+
+	it('clears hover on mouse leave', () => {
+		const { result } = renderHook(() => useFlamegraphHover(defaultArgs));
+
+		act(() => {
+			result.current.handleHoverMouseMove({
+				clientX: 150,
+				clientY: 61,
+			} as React.MouseEvent);
+		});
+
+		act(() => {
+			result.current.handleHoverMouseLeave();
+		});
+
+		expect(result.current.hoveredSpanId).toBeNull();
+		expect(result.current.tooltipContent).toBeNull();
+	});
+
+	it('suppresses click when drag distance exceeds threshold', () => {
+		const { result } = renderHook(() => useFlamegraphHover(defaultArgs));
+
+		act(() => {
+			result.current.handleMouseDownForClick({
+				clientX: 100,
+				clientY: 50,
+			} as React.MouseEvent);
+		});
+
+		act(() => {
+			result.current.handleClick({
+				clientX: 150,
+				clientY: 100,
+			} as React.MouseEvent);
+		});
+
+		expect(defaultArgs.onSpanClick).not.toHaveBeenCalled();
+	});
+
+	it('calls onSpanClick when clicking on span', () => {
+		const { result } = renderHook(() => useFlamegraphHover(defaultArgs));
+
+		act(() => {
+			result.current.handleClick({
+				clientX: 150,
+				clientY: 61,
+			} as React.MouseEvent);
+		});
+
+		expect(defaultArgs.onSpanClick).toHaveBeenCalledWith('hover-span');
+	});
+
+	it('uses clientX/clientY for tooltip positioning', () => {
+		const { result } = renderHook(() => useFlamegraphHover(defaultArgs));
+
+		act(() => {
+			result.current.handleHoverMouseMove({
+				clientX: 200,
+				clientY: 60,
+			} as React.MouseEvent);
+		});
+
+		expect(result.current.tooltipContent?.clientX).toBe(200);
+		expect(result.current.tooltipContent?.clientY).toBe(60);
+	});
+
+	it('does not update hover during drag', () => {
+		const { result } = renderHook(() => useFlamegraphHover(defaultArgs));
+		defaultArgs.isDraggingRef.current = true;
+
+		act(() => {
+			result.current.handleHoverMouseMove({
+				clientX: 150,
+				clientY: 61,
+			} as React.MouseEvent);
+		});
+
+		expect(result.current.hoveredSpanId).toBeNull();
+	});
+});

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/__tests__/useFlamegraphZoom.test.ts

@@ -0,0 +1,279 @@
+import { act, renderHook } from '@testing-library/react';
+
+import { DEFAULT_ROW_HEIGHT, MIN_VISIBLE_SPAN_MS } from '../constants';
+import { useFlamegraphZoom } from '../hooks/useFlamegraphZoom';
+import { MOCK_TRACE_METADATA } from './testUtils';
+
+function createMockCanvas(): HTMLCanvasElement {
+	const canvas = document.createElement('canvas');
+	canvas.width = 800;
+	canvas.height = 400;
+	canvas.getBoundingClientRect = jest.fn(
+		(): DOMRect =>
+			({
+				left: 0,
+				top: 0,
+				width: 800,
+				height: 400,
+				x: 0,
+				y: 0,
+				bottom: 400,
+				right: 800,
+				toJSON: (): Record<string, unknown> => ({}),
+			} as DOMRect),
+	);
+	return canvas;
+}
+
+describe('useFlamegraphZoom', () => {
+	const traceMetadata = { ...MOCK_TRACE_METADATA };
+
+	beforeEach(() => {
+		Object.defineProperty(window, 'devicePixelRatio', {
+			configurable: true,
+			value: 1,
+		});
+	});
+
+	it('handleResetZoom restores traceMetadata.startTime/endTime', () => {
+		const setViewStartTs = jest.fn();
+		const setViewEndTs = jest.fn();
+		const setRowHeight = jest.fn();
+		const viewStartRef = { current: 100 };
+		const viewEndRef = { current: 500 };
+		const rowHeightRef = { current: 30 };
+		const canvasRef = { current: createMockCanvas() };
+
+		const { result } = renderHook(() =>
+			useFlamegraphZoom({
+				canvasRef,
+				traceMetadata,
+				viewStartRef,
+				viewEndRef,
+				rowHeightRef,
+				setViewStartTs,
+				setViewEndTs,
+				setRowHeight,
+			}),
+		);
+
+		act(() => {
+			result.current.handleResetZoom();
+		});
+
+		expect(setViewStartTs).toHaveBeenCalledWith(traceMetadata.startTime);
+		expect(setViewEndTs).toHaveBeenCalledWith(traceMetadata.endTime);
+		expect(setRowHeight).toHaveBeenCalledWith(DEFAULT_ROW_HEIGHT);
+		expect(viewStartRef.current).toBe(traceMetadata.startTime);
+		expect(viewEndRef.current).toBe(traceMetadata.endTime);
+		expect(rowHeightRef.current).toBe(DEFAULT_ROW_HEIGHT);
+	});
+
+	it('wheel zoom in decreases visible time range', async () => {
+		const setViewStartTs = jest.fn();
+		const setViewEndTs = jest.fn();
+		const setRowHeight = jest.fn();
+		const viewStartRef = { current: traceMetadata.startTime };
+		const viewEndRef = { current: traceMetadata.endTime };
+		const rowHeightRef = { current: DEFAULT_ROW_HEIGHT };
+		const canvas = createMockCanvas();
+		const canvasRef = { current: canvas };
+
+		renderHook(() =>
+			useFlamegraphZoom({
+				canvasRef,
+				traceMetadata,
+				viewStartRef,
+				viewEndRef,
+				rowHeightRef,
+				setViewStartTs,
+				setViewEndTs,
+				setRowHeight,
+			}),
+		);
+
+		const initialSpan = viewEndRef.current - viewStartRef.current;
+
+		await act(async () => {
+			canvas.dispatchEvent(
+				new WheelEvent('wheel', {
+					clientX: 400,
+					deltaY: -100,
+					bubbles: true,
+				}),
+			);
+		});
+
+		await act(async () => {
+			await new Promise((r) => requestAnimationFrame(r));
+		});
+
+		expect(setViewStartTs).toHaveBeenCalled();
+		expect(setViewEndTs).toHaveBeenCalled();
+		const [newStart] = setViewStartTs.mock.calls[0] ?? [];
+		const [newEnd] = setViewEndTs.mock.calls[0] ?? [];
+		if (newStart != null && newEnd != null) {
+			const newSpan = newEnd - newStart;
+			expect(newSpan).toBeLessThan(initialSpan);
+		}
+	});
+
+	it('wheel zoom out increases visible time range', async () => {
+		const setViewStartTs = jest.fn();
+		const setViewEndTs = jest.fn();
+		const setRowHeight = jest.fn();
+		const halfSpan = (traceMetadata.endTime - traceMetadata.startTime) / 2;
+		const viewStartRef = { current: traceMetadata.startTime + halfSpan * 0.25 };
+		const viewEndRef = { current: traceMetadata.startTime + halfSpan * 0.75 };
+		const rowHeightRef = { current: DEFAULT_ROW_HEIGHT };
+		const canvas = createMockCanvas();
+		const canvasRef = { current: canvas };
+
+		renderHook(() =>
+			useFlamegraphZoom({
+				canvasRef,
+				traceMetadata,
+				viewStartRef,
+				viewEndRef,
+				rowHeightRef,
+				setViewStartTs,
+				setViewEndTs,
+				setRowHeight,
+			}),
+		);
+
+		const initialSpan = viewEndRef.current - viewStartRef.current;
+
+		await act(async () => {
+			canvas.dispatchEvent(
+				new WheelEvent('wheel', {
+					clientX: 400,
+					deltaY: 100,
+					bubbles: true,
+				}),
+			);
+		});
+
+		await act(async () => {
+			await new Promise((r) => requestAnimationFrame(r));
+		});
+
+		expect(setViewStartTs).toHaveBeenCalled();
+		expect(setViewEndTs).toHaveBeenCalled();
+		const [newStart] = setViewStartTs.mock.calls[0] ?? [];
+		const [newEnd] = setViewEndTs.mock.calls[0] ?? [];
+		if (newStart != null && newEnd != null) {
+			const newSpan = newEnd - newStart;
+			expect(newSpan).toBeGreaterThanOrEqual(initialSpan);
+		}
+	});
+
+	it('clamps zoom to MIN_VISIBLE_SPAN_MS', async () => {
+		const setViewStartTs = jest.fn();
+		const setViewEndTs = jest.fn();
+		const setRowHeight = jest.fn();
+		const viewStartRef = { current: traceMetadata.startTime };
+		const viewEndRef = { current: traceMetadata.startTime + 100 };
+		const rowHeightRef = { current: DEFAULT_ROW_HEIGHT };
+		const canvas = createMockCanvas();
+		const canvasRef = { current: canvas };
+
+		renderHook(() =>
+			useFlamegraphZoom({
+				canvasRef,
+				traceMetadata,
+				viewStartRef,
+				viewEndRef,
+				rowHeightRef,
+				setViewStartTs,
+				setViewEndTs,
+				setRowHeight,
+			}),
+		);
+
+		await act(async () => {
+			canvas.dispatchEvent(
+				new WheelEvent('wheel', {
+					clientX: 400,
+					deltaY: 10000,
+					bubbles: true,
+				}),
+			);
+		});
+
+		await act(async () => {
+			await new Promise((r) => requestAnimationFrame(r));
+		});
+
+		const [newStart] = setViewStartTs.mock.calls[0] ?? [];
+		const [newEnd] = setViewEndTs.mock.calls[0] ?? [];
+		if (newStart != null && newEnd != null) {
+			const newSpan = newEnd - newStart;
+			expect(newSpan).toBeGreaterThanOrEqual(MIN_VISIBLE_SPAN_MS);
+		}
+	});
+
+	it('clamps viewStart/viewEnd to trace bounds', async () => {
+		const setViewStartTs = jest.fn();
+		const setViewEndTs = jest.fn();
+		const setRowHeight = jest.fn();
+		const viewStartRef = { current: traceMetadata.startTime };
+		const viewEndRef = { current: traceMetadata.endTime };
+		const rowHeightRef = { current: DEFAULT_ROW_HEIGHT };
+		const canvas = createMockCanvas();
+		const canvasRef = { current: canvas };
+
+		renderHook(() =>
+			useFlamegraphZoom({
+				canvasRef,
+				traceMetadata,
+				viewStartRef,
+				viewEndRef,
+				rowHeightRef,
+				setViewStartTs,
+				setViewEndTs,
+				setRowHeight,
+			}),
+		);
+
+		await act(async () => {
+			canvas.dispatchEvent(
+				new WheelEvent('wheel', {
+					clientX: 400,
+					deltaY: -5000,
+					bubbles: true,
+				}),
+			);
+		});
+
+		await act(async () => {
+			await new Promise((r) => requestAnimationFrame(r));
+		});
+
+		const [newStart] = setViewStartTs.mock.calls[0] ?? [];
+		const [newEnd] = setViewEndTs.mock.calls[0] ?? [];
+		if (newStart != null && newEnd != null) {
+			expect(newStart).toBeGreaterThanOrEqual(traceMetadata.startTime);
+			expect(newEnd).toBeLessThanOrEqual(traceMetadata.endTime);
+		}
+	});
+
+	it('returns isOverFlamegraphRef', () => {
+		const canvasRef = { current: createMockCanvas() };
+		const { result } = renderHook(() =>
+			useFlamegraphZoom({
+				canvasRef,
+				traceMetadata,
+				viewStartRef: { current: 0 },
+				viewEndRef: { current: 1000 },
+				rowHeightRef: { current: 24 },
+				setViewStartTs: jest.fn(),
+				setViewEndTs: jest.fn(),
+				setRowHeight: jest.fn(),
+			}),
+		);
+
+		expect(result.current.isOverFlamegraphRef).toBeDefined();
+		expect(result.current.isOverFlamegraphRef.current).toBe(false);
+	});
+});

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/__tests__/useScrollToSpan.test.tsx

@@ -0,0 +1,212 @@
+import type { Dispatch, SetStateAction } from 'react';
+import { useRef } from 'react';
+import { act, render, waitFor } from '@testing-library/react';
+
+import { useScrollToSpan } from '../hooks/useScrollToSpan';
+import { MOCK_SPANS, MOCK_TRACE_METADATA } from './testUtils';
+
+function TestWrapper({
+	firstSpanAtFetchLevel,
+	spans,
+	traceMetadata,
+	setViewStartTs,
+	setViewEndTs,
+	setScrollTop,
+}: {
+	firstSpanAtFetchLevel: string;
+	spans: typeof MOCK_SPANS;
+	traceMetadata: typeof MOCK_TRACE_METADATA;
+	setViewStartTs: Dispatch<SetStateAction<number>>;
+	setViewEndTs: Dispatch<SetStateAction<number>>;
+	setScrollTop: Dispatch<SetStateAction<number>>;
+}): JSX.Element {
+	const containerRef = useRef<HTMLDivElement>(null);
+	const viewStartRef = useRef(traceMetadata.startTime);
+	const viewEndRef = useRef(traceMetadata.endTime);
+	const scrollTopRef = useRef(0);
+
+	useScrollToSpan({
+		firstSpanAtFetchLevel,
+		spans,
+		traceMetadata,
+		containerRef,
+		viewStartRef,
+		viewEndRef,
+		scrollTopRef,
+		rowHeight: 24,
+		setViewStartTs,
+		setViewEndTs,
+		setScrollTop,
+	});
+
+	return <div ref={containerRef} data-testid="container" />;
+}
+
+describe('useScrollToSpan', () => {
+	beforeEach(() => {
+		Object.defineProperty(HTMLElement.prototype, 'clientHeight', {
+			configurable: true,
+			value: 400,
+		});
+	});
+
+	it('does not update when firstSpanAtFetchLevel is empty', async () => {
+		const setViewStartTs = jest.fn();
+		const setViewEndTs = jest.fn();
+		const setScrollTop = jest.fn();
+
+		render(
+			<TestWrapper
+				firstSpanAtFetchLevel=""
+				spans={MOCK_SPANS}
+				traceMetadata={MOCK_TRACE_METADATA}
+				setViewStartTs={setViewStartTs}
+				setViewEndTs={setViewEndTs}
+				setScrollTop={setScrollTop}
+			/>,
+		);
+
+		await waitFor(() => {
+			expect(setViewStartTs).not.toHaveBeenCalled();
+			expect(setViewEndTs).not.toHaveBeenCalled();
+			expect(setScrollTop).not.toHaveBeenCalled();
+		});
+	});
+
+	it('does not update when spans are empty', async () => {
+		const setViewStartTs = jest.fn();
+		const setViewEndTs = jest.fn();
+		const setScrollTop = jest.fn();
+
+		render(
+			<TestWrapper
+				firstSpanAtFetchLevel="root"
+				spans={[]}
+				traceMetadata={MOCK_TRACE_METADATA}
+				setViewStartTs={setViewStartTs}
+				setViewEndTs={setViewEndTs}
+				setScrollTop={setScrollTop}
+			/>,
+		);
+
+		await waitFor(() => {
+			expect(setViewStartTs).not.toHaveBeenCalled();
+			expect(setViewEndTs).not.toHaveBeenCalled();
+			expect(setScrollTop).not.toHaveBeenCalled();
+		});
+	});
+
+	it('does not update when target span not found', async () => {
+		const setViewStartTs = jest.fn();
+		const setViewEndTs = jest.fn();
+		const setScrollTop = jest.fn();
+
+		render(
+			<TestWrapper
+				firstSpanAtFetchLevel="nonexistent"
+				spans={MOCK_SPANS}
+				traceMetadata={MOCK_TRACE_METADATA}
+				setViewStartTs={setViewStartTs}
+				setViewEndTs={setViewEndTs}
+				setScrollTop={setScrollTop}
+			/>,
+		);
+
+		await waitFor(() => {
+			expect(setViewStartTs).not.toHaveBeenCalled();
+			expect(setViewEndTs).not.toHaveBeenCalled();
+			expect(setScrollTop).not.toHaveBeenCalled();
+		});
+	});
+
+	it('calls setters when target span found', async () => {
+		const setViewStartTs = jest.fn();
+		const setViewEndTs = jest.fn();
+		const setScrollTop = jest.fn();
+
+		const { getByTestId } = render(
+			<TestWrapper
+				firstSpanAtFetchLevel="grandchild"
+				spans={MOCK_SPANS}
+				traceMetadata={MOCK_TRACE_METADATA}
+				setViewStartTs={setViewStartTs}
+				setViewEndTs={setViewEndTs}
+				setScrollTop={setScrollTop}
+			/>,
+		);
+
+		expect(getByTestId('container')).toBeInTheDocument();
+
+		await waitFor(() => {
+			expect(setViewStartTs).toHaveBeenCalled();
+			expect(setViewEndTs).toHaveBeenCalled();
+			expect(setScrollTop).toHaveBeenCalled();
+		});
+
+		const [viewStart] = setViewStartTs.mock.calls[0];
+		const [viewEnd] = setViewEndTs.mock.calls[0];
+		const [scrollTop] = setScrollTop.mock.calls[0];
+
+		expect(viewEnd - viewStart).toBeGreaterThan(0);
+		expect(viewStart).toBeGreaterThanOrEqual(MOCK_TRACE_METADATA.startTime);
+		expect(viewEnd).toBeLessThanOrEqual(MOCK_TRACE_METADATA.endTime);
+		expect(scrollTop).toBeGreaterThanOrEqual(0);
+	});
+
+	it('centers span vertically (scrollTop centers span row)', async () => {
+		const setScrollTop = jest.fn();
+
+		await act(async () => {
+			render(
+				<TestWrapper
+					firstSpanAtFetchLevel="grandchild"
+					spans={MOCK_SPANS}
+					traceMetadata={MOCK_TRACE_METADATA}
+					setViewStartTs={jest.fn()}
+					setViewEndTs={jest.fn()}
+					setScrollTop={setScrollTop}
+				/>,
+			);
+		});
+
+		await waitFor(() => expect(setScrollTop).toHaveBeenCalled());
+
+		const [scrollTop] = setScrollTop.mock.calls[0];
+		const levelIndex = 2;
+		const rowHeight = 24;
+		const viewportHeight = 400;
+		const expectedCenter =
+			levelIndex * rowHeight - viewportHeight / 2 + rowHeight / 2;
+		expect(scrollTop).toBeCloseTo(Math.max(0, expectedCenter), -1);
+	});
+
+	it('zooms horizontally to span with 2x duration padding', async () => {
+		const setViewStartTs = jest.fn();
+		const setViewEndTs = jest.fn();
+
+		await act(async () => {
+			render(
+				<TestWrapper
+					firstSpanAtFetchLevel="root"
+					spans={MOCK_SPANS}
+					traceMetadata={MOCK_TRACE_METADATA}
+					setViewStartTs={setViewStartTs}
+					setViewEndTs={setViewEndTs}
+					setScrollTop={jest.fn()}
+				/>,
+			);
+		});
+
+		await waitFor(() => {
+			expect(setViewStartTs).toHaveBeenCalled();
+			expect(setViewEndTs).toHaveBeenCalled();
+		});
+
+		const [viewStart] = setViewStartTs.mock.calls[0];
+		const [viewEnd] = setViewEndTs.mock.calls[0];
+		const visibleWindow = viewEnd - viewStart;
+		const rootSpan = MOCK_SPANS[0][0];
+		const spanDurationMs = rootSpan.durationNano / 1e6;
+		expect(visibleWindow).toBeGreaterThanOrEqual(Math.max(spanDurationMs * 2, 5));
+	});
+});

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/__tests__/utils.math.test.ts

@@ -0,0 +1,135 @@
+import {
+	clamp,
+	findSpanById,
+	formatDuration,
+	getFlamegraphRowMetrics,
+} from '../utils';
+import { MOCK_SPANS } from './testUtils';
+
+jest.mock('container/TraceDetail/utils', () => ({
+	convertTimeToRelevantUnit: (
+		valueMs: number,
+	): { time: number; timeUnitName: string } => {
+		if (valueMs === 0) {
+			return { time: 0, timeUnitName: 'ms' };
+		}
+		if (valueMs < 1) {
+			return { time: valueMs, timeUnitName: 'ms' };
+		}
+		if (valueMs < 1000) {
+			return { time: valueMs, timeUnitName: 'ms' };
+		}
+		if (valueMs < 60_000) {
+			return { time: valueMs / 1000, timeUnitName: 's' };
+		}
+		if (valueMs < 3_600_000) {
+			return { time: valueMs / 60_000, timeUnitName: 'm' };
+		}
+		return { time: valueMs / 3_600_000, timeUnitName: 'hr' };
+	},
+}));
+
+describe('Pure Math and Data Utils', () => {
+	describe('clamp', () => {
+		it('returns value when within range', () => {
+			expect(clamp(5, 0, 10)).toBe(5);
+			expect(clamp(-3, -5, 5)).toBe(-3);
+		});
+
+		it('returns min when value is below min', () => {
+			expect(clamp(-1, 0, 10)).toBe(0);
+			expect(clamp(2, 5, 10)).toBe(5);
+		});
+
+		it('returns max when value is above max', () => {
+			expect(clamp(11, 0, 10)).toBe(10);
+			expect(clamp(100, 0, 50)).toBe(50);
+		});
+
+		it('handles min === max', () => {
+			expect(clamp(5, 7, 7)).toBe(7);
+			expect(clamp(7, 7, 7)).toBe(7);
+		});
+	});
+
+	describe('findSpanById', () => {
+		it('finds span in first level', () => {
+			const result = findSpanById(MOCK_SPANS, 'root');
+			expect(result).not.toBeNull();
+			expect(result?.span.spanId).toBe('root');
+			expect(result?.levelIndex).toBe(0);
+		});
+
+		it('finds span in nested level', () => {
+			const result = findSpanById(MOCK_SPANS, 'grandchild');
+			expect(result).not.toBeNull();
+			expect(result?.span.spanId).toBe('grandchild');
+			expect(result?.levelIndex).toBe(2);
+		});
+
+		it('returns null when span not found', () => {
+			expect(findSpanById(MOCK_SPANS, 'nonexistent')).toBeNull();
+		});
+
+		it('handles empty spans', () => {
+			expect(findSpanById([], 'root')).toBeNull();
+			expect(findSpanById([[], []], 'root')).toBeNull();
+		});
+	});
+
+	describe('getFlamegraphRowMetrics', () => {
+		it('computes normal row height metrics (24px)', () => {
+			const m = getFlamegraphRowMetrics(24);
+			expect(m.ROW_HEIGHT).toBe(24);
+			expect(m.SPAN_BAR_HEIGHT).toBe(22);
+			expect(m.SPAN_BAR_Y_OFFSET).toBe(1);
+			expect(m.EVENT_DOT_SIZE).toBe(6);
+		});
+
+		it('clamps span bar height to max for large row heights', () => {
+			const m = getFlamegraphRowMetrics(100);
+			expect(m.SPAN_BAR_HEIGHT).toBe(22);
+			expect(m.SPAN_BAR_Y_OFFSET).toBe(39);
+		});
+
+		it('clamps span bar height to min for small row heights', () => {
+			const m = getFlamegraphRowMetrics(6);
+			expect(m.SPAN_BAR_HEIGHT).toBe(8);
+			// spanBarYOffset = floor((6-8)/2) = -1 when bar exceeds row height
+			expect(m.SPAN_BAR_Y_OFFSET).toBe(-1);
+		});
+
+		it('clamps event dot size within min/max', () => {
+			const mSmall = getFlamegraphRowMetrics(6);
+			expect(mSmall.EVENT_DOT_SIZE).toBe(4);
+
+			const mLarge = getFlamegraphRowMetrics(24);
+			expect(mLarge.EVENT_DOT_SIZE).toBe(6);
+		});
+	});
+
+	describe('formatDuration', () => {
+		it('formats nanos as ms', () => {
+			// 1e6 nanos = 1ms
+			expect(formatDuration(1_000_000)).toBe('1ms');
+		});
+
+		it('formats larger durations as s/m/hr', () => {
+			// 2e9 nanos = 2000ms = 2s
+			expect(formatDuration(2_000_000_000)).toBe('2s');
+		});
+
+		it('formats zero duration', () => {
+			expect(formatDuration(0)).toBe('0ms');
+		});
+
+		it('formats very small values', () => {
+			// 1000 nanos = 0.001ms → mock returns { time: 0.001, timeUnitName: 'ms' }
+			expect(formatDuration(1000)).toBe('0ms');
+		});
+
+		it('formats decimal seconds correctly', () => {
+			expect(formatDuration(1_500_000_000)).toBe('1.5s');
+		});
+	});
+});

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/__tests__/utils.presentation.test.ts

@@ -0,0 +1,67 @@
+import { getSpanColor } from '../utils';
+import { MOCK_SPAN } from './testUtils';
+
+const mockGenerateColor = jest.fn();
+
+jest.mock('lib/uPlotLib/utils/generateColor', () => ({
+	generateColor: (key: string, colorMap: Record<string, string>): string =>
+		mockGenerateColor(key, colorMap),
+}));
+
+describe('Presentation / Styling Utils', () => {
+	beforeEach(() => {
+		jest.clearAllMocks();
+		mockGenerateColor.mockReturnValue('#2F80ED');
+	});
+
+	describe('getSpanColor', () => {
+		it('uses generated service color for normal span', () => {
+			mockGenerateColor.mockReturnValue('#1890ff');
+
+			const color = getSpanColor({
+				span: { ...MOCK_SPAN, hasError: false },
+				isDarkMode: false,
+			});
+
+			expect(mockGenerateColor).toHaveBeenCalledWith(
+				MOCK_SPAN.serviceName,
+				expect.any(Object),
+			);
+			expect(color).toBe('#1890ff');
+		});
+
+		it('overrides with error color in light mode when span has error', () => {
+			mockGenerateColor.mockReturnValue('#1890ff');
+
+			const color = getSpanColor({
+				span: { ...MOCK_SPAN, hasError: true },
+				isDarkMode: false,
+			});
+
+			expect(color).toBe('rgb(220, 38, 38)');
+		});
+
+		it('overrides with error color in dark mode when span has error', () => {
+			mockGenerateColor.mockReturnValue('#1890ff');
+
+			const color = getSpanColor({
+				span: { ...MOCK_SPAN, hasError: true },
+				isDarkMode: true,
+			});
+
+			expect(color).toBe('rgb(239, 68, 68)');
+		});
+
+		it('passes serviceName to generateColor', () => {
+			getSpanColor({
+				span: { ...MOCK_SPAN, serviceName: 'my-service' },
+				isDarkMode: false,
+			});
+
+			expect(mockGenerateColor).toHaveBeenCalledWith(
+				'my-service',
+				expect.any(Object),
+			);
+		});
+	});
+});

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/computeVisualLayout.ts

@@ -0,0 +1,370 @@
+/* eslint-disable sonarjs/cognitive-complexity */
+import { FlamegraphSpan } from 'types/api/trace/getTraceFlamegraph';
+
+export interface ConnectorLine {
+	parentRow: number;
+	childRow: number;
+	timestampMs: number;
+	serviceName: string;
+}
+
+export interface VisualLayout {
+	visualRows: FlamegraphSpan[][];
+	spanToVisualRow: Record<string, number>;
+	connectors: ConnectorLine[];
+	totalVisualRows: number;
+}
+
+/**
+ * Computes an overlap-safe visual layout for flamegraph spans using DFS ordering.
+ *
+ * Builds a parent→children tree from parentSpanId, then traverses in DFS pre-order.
+ * Each span is placed at parentRow+1 if free, otherwise scans upward row-by-row
+ * until finding a non-overlapping row. This keeps children visually close to their
+ * parents and avoids the BFS problem where distant siblings push children far down.
+ */
+export function computeVisualLayout(spans: FlamegraphSpan[][]): VisualLayout {
+	const spanToVisualRow = new Map<string, number>();
+	const visualRowsMap = new Map<number, FlamegraphSpan[]>();
+	let maxRow = -1;
+
+	// Per-row interval list for overlap detection
+	// Each entry: [startTime, endTime]
+	const rowIntervals = new Map<number, Array<[number, number]>>();
+
+	// function hasOverlap(row: number, startTime: number, endTime: number): boolean {
+	// 	const intervals = rowIntervals.get(row);
+	// 	if (!intervals) {
+	// 		return false;
+	// 	}
+	// 	for (const [s, e] of intervals) {
+	// 		if (startTime < e && endTime > s) {
+	// 			return true;
+	// 		}
+	// 	}
+	// 	return false;
+	// }
+
+	function addToRow(row: number, span: FlamegraphSpan): void {
+		spanToVisualRow.set(span.spanId, row);
+		let arr = visualRowsMap.get(row);
+		if (!arr) {
+			arr = [];
+			visualRowsMap.set(row, arr);
+		}
+		arr.push(span);
+
+		const startTime = span.timestamp;
+		const endTime = span.timestamp + span.durationNano / 1e6;
+		let intervals = rowIntervals.get(row);
+		if (!intervals) {
+			intervals = [];
+			rowIntervals.set(row, intervals);
+		}
+		intervals.push([startTime, endTime]);
+
+		if (row > maxRow) {
+			maxRow = row;
+		}
+	}
+
+	// Flatten all spans and build lookup + children map
+	const spanMap = new Map<string, FlamegraphSpan>();
+	const childrenMap = new Map<string, FlamegraphSpan[]>();
+	const allSpans: FlamegraphSpan[] = [];
+
+	for (const level of spans) {
+		for (const span of level) {
+			allSpans.push(span);
+			spanMap.set(span.spanId, span);
+		}
+	}
+
+	// Extract parentSpanId — the field may be missing at runtime when the API
+	// returns `references` instead.  Fall back to the first CHILD_OF reference.
+	function getParentId(span: FlamegraphSpan): string {
+		if (span.parentSpanId) {
+			return span.parentSpanId;
+		}
+		// eslint-disable-next-line @typescript-eslint/no-explicit-any
+		const refs = (span as any).references as
+			| Array<{ spanId?: string; refType?: string }>
+			| undefined;
+		if (refs) {
+			for (const ref of refs) {
+				if (ref.refType === 'CHILD_OF' && ref.spanId) {
+					return ref.spanId;
+				}
+			}
+		}
+		return '';
+	}
+
+	// Build children map and identify roots
+	const roots: FlamegraphSpan[] = [];
+
+	for (const span of allSpans) {
+		const parentId = getParentId(span);
+		if (!parentId || !spanMap.has(parentId)) {
+			roots.push(span);
+		} else {
+			let children = childrenMap.get(parentId);
+			if (!children) {
+				children = [];
+				childrenMap.set(parentId, children);
+			}
+			children.push(span);
+		}
+	}
+
+	// Sort children by timestamp for deterministic ordering
+	for (const [, children] of childrenMap) {
+		children.sort((a, b) => b.timestamp - a.timestamp);
+	}
+
+	// --- Subtree-unit placement ---
+	// Compute each subtree's layout in isolation, then place as a unit
+	// to guarantee parent-child adjacency within subtrees.
+
+	interface ShapeEntry {
+		span: FlamegraphSpan;
+		relativeRow: number;
+	}
+
+	function hasOverlapIn(
+		intervals: Map<number, Array<[number, number]>>,
+		row: number,
+		startTime: number,
+		endTime: number,
+	): boolean {
+		const rowIntervals = intervals.get(row);
+		if (!rowIntervals) {
+			return false;
+		}
+		for (const [s, e] of rowIntervals) {
+			if (startTime < e && endTime > s) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	function addIntervalTo(
+		intervals: Map<number, Array<[number, number]>>,
+		row: number,
+		startTime: number,
+		endTime: number,
+	): void {
+		let arr = intervals.get(row);
+		if (!arr) {
+			arr = [];
+			intervals.set(row, arr);
+		}
+		arr.push([startTime, endTime]);
+	}
+
+	function hasConnectorConflict(
+		intervals: Map<number, Array<[number, number]>>,
+		row: number,
+		point: number,
+	): boolean {
+		const rowIntervals = intervals.get(row);
+		if (!rowIntervals) {
+			return false;
+		}
+		for (const [s, e] of rowIntervals) {
+			if (point >= s && point < e) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	function hasPointInSpan(
+		connectorPoints: Map<number, number[]>,
+		row: number,
+		startTime: number,
+		endTime: number,
+	): boolean {
+		const points = connectorPoints.get(row);
+		if (!points) {
+			return false;
+		}
+		for (const p of points) {
+			if (p >= startTime && p < endTime) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	function addConnectorPoint(
+		connectorPoints: Map<number, number[]>,
+		row: number,
+		point: number,
+	): void {
+		let arr = connectorPoints.get(row);
+		if (!arr) {
+			arr = [];
+			connectorPoints.set(row, arr);
+		}
+		arr.push(point);
+	}
+
+	function computeSubtreeShape(rootSpan: FlamegraphSpan): ShapeEntry[] {
+		const localIntervals = new Map<number, Array<[number, number]>>();
+		const localConnectorPoints = new Map<number, number[]>();
+		const shape: ShapeEntry[] = [];
+
+		// Place root span at relative row 0
+		const rootStart = rootSpan.timestamp;
+		const rootEnd = rootSpan.timestamp + rootSpan.durationNano / 1e6;
+		shape.push({ span: rootSpan, relativeRow: 0 });
+		addIntervalTo(localIntervals, 0, rootStart, rootEnd);
+
+		const children = childrenMap.get(rootSpan.spanId);
+		if (children) {
+			for (const child of children) {
+				const childShape = computeSubtreeShape(child);
+				const connectorX = child.timestamp;
+				const offset = findPlacement(
+					childShape,
+					1,
+					localIntervals,
+					localConnectorPoints,
+					connectorX,
+				);
+
+				// Record connector points for intermediate rows (1 to offset-1)
+				for (let r = 1; r < offset; r++) {
+					addConnectorPoint(localConnectorPoints, r, connectorX);
+				}
+
+				// Place child shape into local state at offset
+				for (const entry of childShape) {
+					const actualRow = entry.relativeRow + offset;
+					shape.push({ span: entry.span, relativeRow: actualRow });
+					const s = entry.span.timestamp;
+					const e = entry.span.timestamp + entry.span.durationNano / 1e6;
+					addIntervalTo(localIntervals, actualRow, s, e);
+				}
+			}
+		}
+
+		return shape;
+	}
+
+	function findPlacement(
+		shape: ShapeEntry[],
+		minOffset: number,
+		intervals: Map<number, Array<[number, number]>>,
+		connectorPoints?: Map<number, number[]>,
+		connectorX?: number,
+	): number {
+		// Track the first offset that passes Checks 1 & 2 as a fallback.
+		// Check 3 (connector vs span) is monotonically failing: once it fails
+		// at offset K, all offsets > K also fail (more intermediate rows).
+		// If we can't satisfy Check 3, fall back to the best offset without it.
+		let fallbackOffset = -1;
+
+		for (let offset = minOffset; ; offset++) {
+			let passesSpanChecks = true;
+
+			// Check 1: span vs span (existing)
+			for (const entry of shape) {
+				const targetRow = entry.relativeRow + offset;
+				const s = entry.span.timestamp;
+				const e = entry.span.timestamp + entry.span.durationNano / 1e6;
+				if (hasOverlapIn(intervals, targetRow, s, e)) {
+					passesSpanChecks = false;
+					break;
+				}
+			}
+
+			// Check 2: span vs existing connector points
+			if (passesSpanChecks && connectorPoints) {
+				for (const entry of shape) {
+					const targetRow = entry.relativeRow + offset;
+					const s = entry.span.timestamp;
+					const e = entry.span.timestamp + entry.span.durationNano / 1e6;
+					if (hasPointInSpan(connectorPoints, targetRow, s, e)) {
+						passesSpanChecks = false;
+						break;
+					}
+				}
+			}
+
+			if (!passesSpanChecks) {
+				continue;
+			}
+
+			// This offset passes Checks 1 & 2 — record as fallback
+			if (fallbackOffset === -1) {
+				fallbackOffset = offset;
+			}
+
+			// Check 3: new connector vs existing spans
+			if (connectorX !== undefined) {
+				let connectorClear = true;
+				for (let r = 1; r < offset; r++) {
+					if (hasConnectorConflict(intervals, r, connectorX)) {
+						connectorClear = false;
+						break;
+					}
+				}
+				if (!connectorClear) {
+					// Check 3 will fail for all larger offsets too.
+					// Fall back to the first offset that passed Checks 1 & 2.
+					return fallbackOffset;
+				}
+			}
+
+			return offset;
+		}
+	}
+
+	// Process roots sorted by timestamp
+	roots.sort((a, b) => a.timestamp - b.timestamp);
+	for (const root of roots) {
+		const shape = computeSubtreeShape(root);
+		const offset = findPlacement(shape, 0, rowIntervals);
+		for (const entry of shape) {
+			addToRow(entry.relativeRow + offset, entry.span);
+		}
+	}
+
+	// Build the visualRows array
+	const totalVisualRows = maxRow + 1;
+	const visualRows: FlamegraphSpan[][] = [];
+	for (let i = 0; i < totalVisualRows; i++) {
+		visualRows.push(visualRowsMap.get(i) || []);
+	}
+
+	// Build connector lines for parent-child pairs with row gap > 1
+	const connectors: ConnectorLine[] = [];
+	for (const [parentId, children] of childrenMap) {
+		const parentRow = spanToVisualRow.get(parentId);
+		if (parentRow === undefined) {
+			continue;
+		}
+		for (const child of children) {
+			const childRow = spanToVisualRow.get(child.spanId);
+			if (childRow === undefined || childRow - parentRow <= 1) {
+				continue;
+			}
+			connectors.push({
+				parentRow,
+				childRow,
+				timestampMs: child.timestamp,
+				serviceName: child.serviceName,
+			});
+		}
+	}
+
+	return {
+		visualRows,
+		spanToVisualRow: Object.fromEntries(spanToVisualRow),
+		connectors,
+		totalVisualRows,
+	};
+}

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/constants.ts

@@ -0,0 +1,36 @@
+export const ROW_HEIGHT = 24;
+export const SPAN_BAR_HEIGHT = 22;
+export const SPAN_BAR_Y_OFFSET = Math.floor((ROW_HEIGHT - SPAN_BAR_HEIGHT) / 2);
+export const EVENT_DOT_SIZE = 6;
+
+// Span bar sizing relative to row height (used by getFlamegraphRowMetrics)
+export const SPAN_BAR_HEIGHT_RATIO = SPAN_BAR_HEIGHT / ROW_HEIGHT;
+export const MIN_SPAN_BAR_HEIGHT = 8;
+export const MAX_SPAN_BAR_HEIGHT = SPAN_BAR_HEIGHT;
+
+// Event dot sizing relative to span bar height
+export const EVENT_DOT_SIZE_RATIO = EVENT_DOT_SIZE / SPAN_BAR_HEIGHT;
+export const MIN_EVENT_DOT_SIZE = 4;
+export const MAX_EVENT_DOT_SIZE = EVENT_DOT_SIZE;
+
+export const LABEL_FONT = '11px Inter, sans-serif';
+export const LABEL_PADDING_X = 8;
+export const MIN_WIDTH_FOR_NAME = 30;
+export const MIN_WIDTH_FOR_NAME_AND_DURATION = 80;
+
+// Dynamic row height (vertical zoom) -- disabled for now (MIN === MAX)
+export const MIN_ROW_HEIGHT = 24;
+export const MAX_ROW_HEIGHT = 24;
+export const DEFAULT_ROW_HEIGHT = MIN_ROW_HEIGHT;
+
+// Zoom intensity -- how fast zoom reacts to wheel/pinch delta
+export const PINCH_ZOOM_INTENSITY_H = 0.01;
+export const SCROLL_ZOOM_INTENSITY_H = 0.0015;
+export const PINCH_ZOOM_INTENSITY_V = 0.008;
+export const SCROLL_ZOOM_INTENSITY_V = 0.001;
+
+// Minimum visible time span in ms (prevents zooming to sub-pixel)
+export const MIN_VISIBLE_SPAN_MS = 5;
+
+// Selected span style (dashed border)
+export const DASHED_BORDER_LINE_DASH = [4, 2];

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/hooks/useCanvasSetup.ts

@@ -0,0 +1,55 @@
+import { RefObject, useCallback, useEffect } from 'react';
+
+export function useCanvasSetup(
+	canvasRef: RefObject<HTMLCanvasElement>,
+	containerRef: RefObject<HTMLDivElement>,
+	onDraw: () => void,
+): void {
+	const updateCanvasSize = useCallback(() => {
+		const canvas = canvasRef.current;
+		const container = containerRef.current;
+		if (!canvas || !container) {
+			return;
+		}
+
+		const dpr = window.devicePixelRatio || 1;
+		const rect = container.getBoundingClientRect();
+		const viewportHeight = container.clientHeight;
+
+		canvas.style.width = `${rect.width}px`;
+		canvas.style.height = `${viewportHeight}px`;
+
+		const newWidth = Math.floor(rect.width * dpr);
+		const newHeight = Math.floor(viewportHeight * dpr);
+
+		if (canvas.width !== newWidth || canvas.height !== newHeight) {
+			canvas.width = newWidth;
+			canvas.height = newHeight;
+			onDraw();
+		}
+	}, [canvasRef, containerRef, onDraw]);
+
+	useEffect(() => {
+		const container = containerRef.current;
+		if (!container) {
+			return (): void => {};
+		}
+
+		const resizeObserver = new ResizeObserver(updateCanvasSize);
+		resizeObserver.observe(container);
+		updateCanvasSize();
+
+		// when dpr changes, update the canvas size
+		const dprQuery = window.matchMedia('(resolution: 1dppx)');
+		dprQuery.addEventListener('change', updateCanvasSize);
+
+		return (): void => {
+			resizeObserver.disconnect();
+			dprQuery.removeEventListener('change', updateCanvasSize);
+		};
+	}, [containerRef, updateCanvasSize]);
+
+	useEffect(() => {
+		onDraw();
+	}, [onDraw]);
+}

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/hooks/useFlamegraphDrag.ts

@@ -0,0 +1,170 @@
+import {
+	Dispatch,
+	MouseEvent as ReactMouseEvent,
+	MutableRefObject,
+	RefObject,
+	SetStateAction,
+	useCallback,
+	useRef,
+} from 'react';
+
+import { ITraceMetadata } from '../types';
+import { clamp } from '../utils';
+
+interface UseFlamegraphDragArgs {
+	canvasRef: RefObject<HTMLCanvasElement>;
+	containerRef: RefObject<HTMLDivElement>;
+	traceMetadata: ITraceMetadata;
+	viewStartRef: MutableRefObject<number>;
+	viewEndRef: MutableRefObject<number>;
+	setViewStartTs: Dispatch<SetStateAction<number>>;
+	setViewEndTs: Dispatch<SetStateAction<number>>;
+	scrollTopRef: MutableRefObject<number>;
+	setScrollTop: Dispatch<SetStateAction<number>>;
+	totalHeight: number;
+}
+
+interface UseFlamegraphDragResult {
+	handleMouseDown: (e: ReactMouseEvent) => void;
+	handleMouseMove: (e: ReactMouseEvent) => void;
+	handleMouseUp: () => void;
+	handleDragMouseLeave: () => void;
+	isDraggingRef: MutableRefObject<boolean>;
+}
+
+export function useFlamegraphDrag(
+	args: UseFlamegraphDragArgs,
+): UseFlamegraphDragResult {
+	const {
+		canvasRef,
+		containerRef,
+		traceMetadata,
+		viewStartRef,
+		viewEndRef,
+		setViewStartTs,
+		setViewEndTs,
+		scrollTopRef,
+		setScrollTop,
+		totalHeight,
+	} = args;
+
+	const isDraggingRef = useRef(false);
+	const dragStartRef = useRef<{ x: number; y: number } | null>(null);
+	const dragDistanceRef = useRef(0);
+
+	const clampScrollTop = useCallback(
+		(next: number): number => {
+			const container = containerRef.current;
+			if (!container) {
+				return 0;
+			}
+			const viewportHeight = container.clientHeight;
+			const maxScroll = Math.max(0, totalHeight - viewportHeight);
+			return clamp(next, 0, maxScroll);
+		},
+		[containerRef, totalHeight],
+	);
+
+	const handleMouseDown = useCallback(
+		(event: ReactMouseEvent): void => {
+			if (event.button !== 0) {
+				return;
+			}
+			event.preventDefault();
+
+			isDraggingRef.current = true;
+			dragStartRef.current = { x: event.clientX, y: event.clientY };
+			dragDistanceRef.current = 0;
+
+			const canvas = canvasRef.current;
+			if (canvas) {
+				canvas.style.cursor = 'grabbing';
+			}
+		},
+		[canvasRef],
+	);
+
+	const handleMouseMove = useCallback(
+		(event: ReactMouseEvent): void => {
+			if (!isDraggingRef.current || !dragStartRef.current) {
+				return;
+			}
+
+			const canvas = canvasRef.current;
+			if (!canvas) {
+				return;
+			}
+
+			const rect = canvas.getBoundingClientRect();
+			const deltaX = event.clientX - dragStartRef.current.x;
+			const deltaY = event.clientY - dragStartRef.current.y;
+
+			dragDistanceRef.current = Math.sqrt(deltaX * deltaX + deltaY * deltaY);
+
+			// --- Horizontal pan ---
+			const timeSpan = viewEndRef.current - viewStartRef.current;
+			const deltaTime = (deltaX / rect.width) * timeSpan;
+
+			const newStart = viewStartRef.current - deltaTime;
+			const clampedStart = clamp(
+				newStart,
+				traceMetadata.startTime,
+				traceMetadata.endTime - timeSpan,
+			);
+			const clampedEnd = clampedStart + timeSpan;
+
+			viewStartRef.current = clampedStart;
+			viewEndRef.current = clampedEnd;
+			setViewStartTs(clampedStart);
+			setViewEndTs(clampedEnd);
+
+			// --- Vertical scroll pan ---
+			const nextScrollTop = clampScrollTop(scrollTopRef.current - deltaY);
+			scrollTopRef.current = nextScrollTop;
+			setScrollTop(nextScrollTop);
+
+			dragStartRef.current = { x: event.clientX, y: event.clientY };
+		},
+		[
+			canvasRef,
+			traceMetadata,
+			viewStartRef,
+			viewEndRef,
+			setViewStartTs,
+			setViewEndTs,
+			scrollTopRef,
+			setScrollTop,
+			clampScrollTop,
+		],
+	);
+
+	const handleMouseUp = useCallback((): void => {
+		isDraggingRef.current = false;
+		dragStartRef.current = null;
+		dragDistanceRef.current = 0;
+
+		const canvas = canvasRef.current;
+		if (canvas) {
+			canvas.style.cursor = 'grab';
+		}
+	}, [canvasRef]);
+
+	// const handleDragMouseLeave = useCallback((): void => {
+	// 	isDraggingRef.current = false;
+	// 	dragStartRef.current = null;
+	// 	dragDistanceRef.current = 0;
+
+	// 	const canvas = canvasRef.current;
+	// 	if (canvas) {
+	// 		canvas.style.cursor = 'grab';
+	// 	}
+	// }, [canvasRef]);
+
+	return {
+		handleMouseDown,
+		handleMouseMove,
+		handleMouseUp,
+		handleDragMouseLeave: handleMouseUp, // Same logic for mouse up and leaving the canvas
+		isDraggingRef,
+	};
+}

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/hooks/useFlamegraphDraw.ts

@@ -0,0 +1,317 @@
+import React, { RefObject, useCallback, useRef } from 'react';
+import { themeColors } from 'constants/theme';
+import { generateColor } from 'lib/uPlotLib/utils/generateColor';
+import { FlamegraphSpan } from 'types/api/trace/getTraceFlamegraph';
+
+import { ConnectorLine } from '../computeVisualLayout';
+import { EventRect, SpanRect } from '../types';
+import {
+	clamp,
+	drawSpanBar,
+	FlamegraphRowMetrics,
+	getFlamegraphRowMetrics,
+	getSpanColor,
+} from '../utils';
+
+interface UseFlamegraphDrawArgs {
+	canvasRef: RefObject<HTMLCanvasElement>;
+	containerRef: RefObject<HTMLDivElement>;
+	spans: FlamegraphSpan[][];
+	connectors: ConnectorLine[];
+	viewStartTs: number;
+	viewEndTs: number;
+	scrollTop: number;
+	rowHeight: number;
+	selectedSpanId: string | undefined;
+	hoveredSpanId: string;
+	isDarkMode: boolean;
+	spanRectsRef?: React.MutableRefObject<SpanRect[]>;
+	eventRectsRef?: React.MutableRefObject<EventRect[]>;
+	hoveredEventKey?: string | null;
+}
+
+interface UseFlamegraphDrawResult {
+	drawFlamegraph: () => void;
+	spanRectsRef: RefObject<SpanRect[]>;
+	eventRectsRef: RefObject<EventRect[]>;
+}
+
+const OVERSCAN_ROWS = 4;
+
+interface DrawLevelArgs {
+	ctx: CanvasRenderingContext2D;
+	levelSpans: FlamegraphSpan[];
+	levelIndex: number;
+	y: number;
+	viewStartTs: number;
+	timeSpan: number;
+	cssWidth: number;
+	selectedSpanId: string | undefined;
+	hoveredSpanId: string;
+	isDarkMode: boolean;
+	spanRectsArray: SpanRect[];
+	eventRectsArray: EventRect[];
+	metrics: FlamegraphRowMetrics;
+	hoveredEventKey?: string | null;
+}
+
+function drawLevel(args: DrawLevelArgs): void {
+	const {
+		ctx,
+		levelSpans,
+		levelIndex,
+		y,
+		viewStartTs,
+		timeSpan,
+		cssWidth,
+		selectedSpanId,
+		hoveredSpanId,
+		isDarkMode,
+		spanRectsArray,
+		eventRectsArray,
+		metrics,
+		hoveredEventKey,
+	} = args;
+
+	const viewEndTs = viewStartTs + timeSpan;
+
+	for (let i = 0; i < levelSpans.length; i++) {
+		const span = levelSpans[i];
+		const spanStartMs = span.timestamp;
+		const spanEndMs = span.timestamp + span.durationNano / 1e6;
+
+		// Time culling -- skip spans entirely outside the visible time window
+		if (spanEndMs < viewStartTs || spanStartMs > viewEndTs) {
+			continue;
+		}
+
+		const leftOffset = ((spanStartMs - viewStartTs) / timeSpan) * cssWidth;
+		const rightEdge = ((spanEndMs - viewStartTs) / timeSpan) * cssWidth;
+		let width = rightEdge - leftOffset;
+
+		// Clamp to visible x-range
+		if (leftOffset < 0) {
+			width += leftOffset;
+			if (width <= 0) {
+				continue;
+			}
+		}
+		if (rightEdge > cssWidth) {
+			width = cssWidth - Math.max(0, leftOffset);
+			if (width <= 0) {
+				continue;
+			}
+		}
+
+		// Minimum 1px width so tiny spans remain visible
+		width = clamp(width, 1, Infinity);
+
+		const color = getSpanColor({ span, isDarkMode });
+
+		drawSpanBar({
+			ctx,
+			span,
+			x: Math.max(0, leftOffset),
+			y,
+			width,
+			levelIndex,
+			spanRectsArray,
+			eventRectsArray,
+			color,
+			isDarkMode,
+			metrics,
+			selectedSpanId,
+			hoveredSpanId,
+			hoveredEventKey,
+		});
+	}
+}
+
+interface DrawConnectorLinesArgs {
+	ctx: CanvasRenderingContext2D;
+	connectors: ConnectorLine[];
+	scrollTop: number;
+	viewStartTs: number;
+	timeSpan: number;
+	cssWidth: number;
+	viewportHeight: number;
+	metrics: FlamegraphRowMetrics;
+}
+
+function drawConnectorLines(args: DrawConnectorLinesArgs): void {
+	const {
+		ctx,
+		connectors,
+		scrollTop,
+		viewStartTs,
+		timeSpan,
+		cssWidth,
+		viewportHeight,
+		metrics,
+	} = args;
+
+	ctx.save();
+	ctx.lineWidth = 1;
+	ctx.globalAlpha = 0.6;
+
+	for (const conn of connectors) {
+		const xFrac = (conn.timestampMs - viewStartTs) / timeSpan;
+		if (xFrac < -0.01 || xFrac > 1.01) {
+			continue;
+		}
+
+		const parentY =
+			conn.parentRow * metrics.ROW_HEIGHT -
+			scrollTop +
+			metrics.SPAN_BAR_Y_OFFSET +
+			metrics.SPAN_BAR_HEIGHT;
+		const childY =
+			conn.childRow * metrics.ROW_HEIGHT - scrollTop + metrics.SPAN_BAR_Y_OFFSET;
+
+		// Skip if entirely outside viewport
+		if (parentY > viewportHeight || childY < 0) {
+			continue;
+		}
+
+		const color = generateColor(
+			conn.serviceName,
+			themeColors.traceDetailColorsV3,
+		);
+		ctx.strokeStyle = color;
+
+		const x = clamp(xFrac * cssWidth, 0, cssWidth);
+		ctx.beginPath();
+		ctx.moveTo(x, parentY);
+		ctx.lineTo(x, childY);
+		ctx.stroke();
+	}
+
+	ctx.restore();
+}
+
+export function useFlamegraphDraw(
+	args: UseFlamegraphDrawArgs,
+): UseFlamegraphDrawResult {
+	const {
+		canvasRef,
+		containerRef,
+		spans,
+		connectors,
+		viewStartTs,
+		viewEndTs,
+		scrollTop,
+		rowHeight,
+		selectedSpanId,
+		hoveredSpanId,
+		isDarkMode,
+		spanRectsRef: spanRectsRefProp,
+		eventRectsRef: eventRectsRefProp,
+		hoveredEventKey,
+	} = args;
+
+	const spanRectsRefInternal = useRef<SpanRect[]>([]);
+	const spanRectsRef = spanRectsRefProp ?? spanRectsRefInternal;
+	const eventRectsRefInternal = useRef<EventRect[]>([]);
+	const eventRectsRef = eventRectsRefProp ?? eventRectsRefInternal;
+
+	const drawFlamegraph = useCallback(() => {
+		const canvas = canvasRef.current;
+		const container = containerRef.current;
+		if (!canvas || !container) {
+			return;
+		}
+
+		const ctx = canvas.getContext('2d');
+		if (!ctx) {
+			return;
+		}
+
+		const dpr = window.devicePixelRatio || 1;
+		ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
+
+		const timeSpan = viewEndTs - viewStartTs;
+		if (timeSpan <= 0) {
+			return;
+		}
+
+		const cssWidth = canvas.width / dpr;
+		const metrics = getFlamegraphRowMetrics(rowHeight);
+
+		// ---- Vertical clipping window ----
+		const viewportHeight = container.clientHeight;
+
+		//starts drawing OVERSCAN_ROWS(4) rows above the visible area.
+		const firstLevel = Math.max(
+			0,
+			Math.floor(scrollTop / metrics.ROW_HEIGHT) - OVERSCAN_ROWS,
+		);
+		// adds 2*OVERSCAN_ROWS extra rows above and below the visible area.
+		const visibleLevelCount =
+			Math.ceil(viewportHeight / metrics.ROW_HEIGHT) + 2 * OVERSCAN_ROWS;
+
+		const lastLevel = Math.min(spans.length - 1, firstLevel + visibleLevelCount);
+
+		ctx.clearRect(0, 0, cssWidth, viewportHeight);
+
+		// ---- Draw connector lines (behind span bars) ----
+		drawConnectorLines({
+			ctx,
+			connectors,
+			scrollTop,
+			viewStartTs,
+			timeSpan,
+			cssWidth,
+			viewportHeight,
+			metrics,
+		});
+
+		const spanRectsArray: SpanRect[] = [];
+		const eventRectsArray: EventRect[] = [];
+		const currentHoveredEventKey = hoveredEventKey ?? null;
+
+		// ---- Draw only visible levels ----
+		for (let levelIndex = firstLevel; levelIndex <= lastLevel; levelIndex++) {
+			const levelSpans = spans[levelIndex];
+			if (!levelSpans) {
+				continue;
+			}
+
+			drawLevel({
+				ctx,
+				levelSpans,
+				levelIndex,
+				y: levelIndex * metrics.ROW_HEIGHT - scrollTop,
+				viewStartTs,
+				timeSpan,
+				cssWidth,
+				selectedSpanId,
+				hoveredSpanId,
+				isDarkMode,
+				spanRectsArray,
+				eventRectsArray,
+				metrics,
+				hoveredEventKey: currentHoveredEventKey,
+			});
+		}
+
+		spanRectsRef.current = spanRectsArray;
+		eventRectsRef.current = eventRectsArray;
+	}, [
+		canvasRef,
+		containerRef,
+		spanRectsRef,
+		eventRectsRef,
+		spans,
+		connectors,
+		viewStartTs,
+		viewEndTs,
+		scrollTop,
+		rowHeight,
+		selectedSpanId,
+		hoveredSpanId,
+		hoveredEventKey,
+		isDarkMode,
+	]);
+
+	return { drawFlamegraph, spanRectsRef, eventRectsRef };
+}

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/hooks/useFlamegraphHover.ts

@@ -0,0 +1,295 @@
+import {
+	Dispatch,
+	MouseEvent as ReactMouseEvent,
+	MutableRefObject,
+	RefObject,
+	SetStateAction,
+	useCallback,
+	useRef,
+	useState,
+} from 'react';
+import { FlamegraphSpan } from 'types/api/trace/getTraceFlamegraph';
+
+import { EventRect, SpanRect } from '../types';
+import { ITraceMetadata } from '../types';
+import { getSpanColor } from '../utils';
+
+function getCanvasPointer(
+	canvas: HTMLCanvasElement,
+	clientX: number,
+	clientY: number,
+): { cssX: number; cssY: number } | null {
+	const rect = canvas.getBoundingClientRect();
+	const dpr = window.devicePixelRatio || 1;
+	const cssWidth = canvas.width / dpr;
+	const cssHeight = canvas.height / dpr;
+	const cssX = (clientX - rect.left) * (cssWidth / rect.width);
+	const cssY = (clientY - rect.top) * (cssHeight / rect.height);
+	return { cssX, cssY };
+}
+
+function findSpanAtPosition(
+	cssX: number,
+	cssY: number,
+	spanRects: SpanRect[],
+): FlamegraphSpan | null {
+	for (let i = spanRects.length - 1; i >= 0; i--) {
+		const r = spanRects[i];
+		if (
+			cssX >= r.x &&
+			cssX <= r.x + r.width &&
+			cssY >= r.y &&
+			cssY <= r.y + r.height
+		) {
+			return r.span;
+		}
+	}
+	return null;
+}
+
+function findEventAtPosition(
+	cssX: number,
+	cssY: number,
+	eventRects: EventRect[],
+): EventRect | null {
+	for (let i = eventRects.length - 1; i >= 0; i--) {
+		const r = eventRects[i];
+		// Manhattan distance check for diamond shape with padding
+		if (Math.abs(r.cx - cssX) + Math.abs(r.cy - cssY) <= r.halfSize * 1.5) {
+			return r;
+		}
+	}
+	return null;
+}
+
+export interface EventTooltipData {
+	name: string;
+	timeOffsetMs: number;
+	isError: boolean;
+	attributeMap: Record<string, string>;
+}
+
+export interface TooltipContent {
+	serviceName: string;
+	spanName: string;
+	status: 'ok' | 'warning' | 'error';
+	startMs: number;
+	durationMs: number;
+	clientX: number;
+	clientY: number;
+	spanColor: string;
+	event?: EventTooltipData;
+}
+
+interface UseFlamegraphHoverArgs {
+	canvasRef: RefObject<HTMLCanvasElement>;
+	spanRectsRef: MutableRefObject<SpanRect[]>;
+	eventRectsRef: MutableRefObject<EventRect[]>;
+	traceMetadata: ITraceMetadata;
+	viewStartTs: number;
+	viewEndTs: number;
+	isDraggingRef: MutableRefObject<boolean>;
+	onSpanClick: (spanId: string) => void;
+	isDarkMode: boolean;
+}
+
+interface UseFlamegraphHoverResult {
+	hoveredSpanId: string | null;
+	setHoveredSpanId: Dispatch<SetStateAction<string | null>>;
+	hoveredEventKey: string | null;
+	handleHoverMouseMove: (e: ReactMouseEvent) => void;
+	handleHoverMouseLeave: () => void;
+	handleMouseDownForClick: (e: ReactMouseEvent) => void;
+	handleClick: (e: ReactMouseEvent) => void;
+	tooltipContent: TooltipContent | null;
+}
+
+export function useFlamegraphHover(
+	args: UseFlamegraphHoverArgs,
+): UseFlamegraphHoverResult {
+	const {
+		canvasRef,
+		spanRectsRef,
+		eventRectsRef,
+		traceMetadata,
+		viewStartTs,
+		viewEndTs,
+		isDraggingRef,
+		onSpanClick,
+		isDarkMode,
+	} = args;
+
+	const [hoveredSpanId, setHoveredSpanId] = useState<string | null>(null);
+	const [hoveredEventKey, setHoveredEventKey] = useState<string | null>(null);
+	const [tooltipContent, setTooltipContent] = useState<TooltipContent | null>(
+		null,
+	);
+
+	const isZoomed =
+		viewStartTs !== traceMetadata.startTime ||
+		viewEndTs !== traceMetadata.endTime;
+
+	const updateCursor = useCallback(
+		(canvas: HTMLCanvasElement, span: FlamegraphSpan | null): void => {
+			if (span) {
+				canvas.style.cursor = 'pointer';
+			} else if (isZoomed) {
+				canvas.style.cursor = 'grab';
+			} else {
+				canvas.style.cursor = 'default';
+			}
+		},
+		[isZoomed],
+	);
+
+	const handleHoverMouseMove = useCallback(
+		(e: ReactMouseEvent): void => {
+			if (isDraggingRef.current) {
+				return;
+			}
+
+			const canvas = canvasRef.current;
+			if (!canvas) {
+				return;
+			}
+
+			const pointer = getCanvasPointer(canvas, e.clientX, e.clientY);
+			if (!pointer) {
+				return;
+			}
+
+			// Check event dots first — they're drawn on top of spans
+			const eventRect = findEventAtPosition(
+				pointer.cssX,
+				pointer.cssY,
+				eventRectsRef.current,
+			);
+
+			if (eventRect) {
+				const { event, span } = eventRect;
+				const eventTimeMs = event.timeUnixNano / 1e6;
+				setHoveredEventKey(`${span.spanId}-${event.name}-${event.timeUnixNano}`);
+				setHoveredSpanId(span.spanId);
+				setTooltipContent({
+					serviceName: span.serviceName || '',
+					spanName: span.name || 'unknown',
+					status: span.hasError ? 'error' : 'ok',
+					startMs: span.timestamp - traceMetadata.startTime,
+					durationMs: span.durationNano / 1e6,
+					clientX: e.clientX,
+					clientY: e.clientY,
+					spanColor: getSpanColor({ span, isDarkMode }),
+					event: {
+						name: event.name,
+						timeOffsetMs: eventTimeMs - span.timestamp,
+						isError: event.isError,
+						attributeMap: event.attributeMap || {},
+					},
+				});
+				updateCursor(canvas, eventRect.span);
+				return;
+			}
+
+			const span = findSpanAtPosition(
+				pointer.cssX,
+				pointer.cssY,
+				spanRectsRef.current,
+			);
+
+			if (span) {
+				setHoveredEventKey(null);
+				setHoveredSpanId(span.spanId);
+				setTooltipContent({
+					serviceName: span.serviceName || '',
+					spanName: span.name || 'unknown',
+					status: span.hasError ? 'error' : 'ok',
+					startMs: span.timestamp - traceMetadata.startTime,
+					durationMs: span.durationNano / 1e6,
+					clientX: e.clientX,
+					clientY: e.clientY,
+					spanColor: getSpanColor({ span, isDarkMode }),
+				});
+				updateCursor(canvas, span);
+			} else {
+				setHoveredEventKey(null);
+				setHoveredSpanId(null);
+				setTooltipContent(null);
+				updateCursor(canvas, null);
+			}
+		},
+		[
+			canvasRef,
+			spanRectsRef,
+			eventRectsRef,
+			traceMetadata.startTime,
+			isDraggingRef,
+			updateCursor,
+			isDarkMode,
+		],
+	);
+
+	const handleHoverMouseLeave = useCallback((): void => {
+		setHoveredEventKey(null);
+		setHoveredSpanId(null);
+		setTooltipContent(null);
+
+		const canvas = canvasRef.current;
+		if (canvas) {
+			updateCursor(canvas, null);
+		}
+	}, [canvasRef, updateCursor]);
+
+	const mouseDownPosRef = useRef<{ x: number; y: number } | null>(null);
+	const CLICK_THRESHOLD = 5;
+
+	const handleMouseDownForClick = useCallback((e: ReactMouseEvent): void => {
+		mouseDownPosRef.current = { x: e.clientX, y: e.clientY };
+	}, []);
+
+	const handleClick = useCallback(
+		(e: ReactMouseEvent): void => {
+			// Detect drag: if mouse moved more than threshold, skip click
+			if (mouseDownPosRef.current) {
+				const dx = e.clientX - mouseDownPosRef.current.x;
+				const dy = e.clientY - mouseDownPosRef.current.y;
+				if (Math.sqrt(dx * dx + dy * dy) > CLICK_THRESHOLD) {
+					mouseDownPosRef.current = null;
+					return;
+				}
+			}
+			mouseDownPosRef.current = null;
+
+			const canvas = canvasRef.current;
+			if (!canvas) {
+				return;
+			}
+
+			const pointer = getCanvasPointer(canvas, e.clientX, e.clientY);
+			if (!pointer) {
+				return;
+			}
+
+			const span = findSpanAtPosition(
+				pointer.cssX,
+				pointer.cssY,
+				spanRectsRef.current,
+			);
+
+			if (span) {
+				onSpanClick(span.spanId);
+			}
+		},
+		[canvasRef, spanRectsRef, onSpanClick],
+	);
+
+	return {
+		hoveredSpanId,
+		setHoveredSpanId,
+		hoveredEventKey,
+		handleHoverMouseMove,
+		handleHoverMouseLeave,
+		handleMouseDownForClick,
+		handleClick,
+		tooltipContent,
+	};
+}

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/hooks/useFlamegraphZoom.ts

@@ -0,0 +1,224 @@
+import {
+	Dispatch,
+	MutableRefObject,
+	RefObject,
+	SetStateAction,
+	useCallback,
+	useEffect,
+	useRef,
+} from 'react';
+
+import {
+	DEFAULT_ROW_HEIGHT,
+	MAX_ROW_HEIGHT,
+	MIN_ROW_HEIGHT,
+	MIN_VISIBLE_SPAN_MS,
+	PINCH_ZOOM_INTENSITY_H,
+	PINCH_ZOOM_INTENSITY_V,
+	SCROLL_ZOOM_INTENSITY_H,
+	SCROLL_ZOOM_INTENSITY_V,
+} from '../constants';
+import { ITraceMetadata } from '../types';
+import { clamp } from '../utils';
+
+interface UseFlamegraphZoomArgs {
+	canvasRef: RefObject<HTMLCanvasElement>;
+	traceMetadata: ITraceMetadata;
+	viewStartRef: MutableRefObject<number>;
+	viewEndRef: MutableRefObject<number>;
+	rowHeightRef: MutableRefObject<number>;
+	setViewStartTs: Dispatch<SetStateAction<number>>;
+	setViewEndTs: Dispatch<SetStateAction<number>>;
+	setRowHeight: Dispatch<SetStateAction<number>>;
+}
+
+interface UseFlamegraphZoomResult {
+	handleResetZoom: () => void;
+	isOverFlamegraphRef: MutableRefObject<boolean>;
+}
+
+function getCanvasPointer(
+	canvasRef: RefObject<HTMLCanvasElement>,
+	clientX: number,
+): { cssX: number; cssWidth: number } | null {
+	const canvas = canvasRef.current;
+	if (!canvas) {
+		return null;
+	}
+
+	const rect = canvas.getBoundingClientRect();
+	const dpr = window.devicePixelRatio || 1;
+	const cssWidth = canvas.width / dpr;
+	const cssX = (clientX - rect.left) * (cssWidth / rect.width);
+
+	return { cssX, cssWidth };
+}
+
+export function useFlamegraphZoom(
+	args: UseFlamegraphZoomArgs,
+): UseFlamegraphZoomResult {
+	const {
+		canvasRef,
+		traceMetadata,
+		viewStartRef,
+		viewEndRef,
+		rowHeightRef,
+		setViewStartTs,
+		setViewEndTs,
+		setRowHeight,
+	} = args;
+
+	const isOverFlamegraphRef = useRef(false);
+	const wheelDeltaRef = useRef(0);
+	const rafRef = useRef<number | null>(null);
+	const lastCursorXRef = useRef(0);
+	const lastCssWidthRef = useRef(1);
+	const lastIsPinchRef = useRef(false);
+	const lastWheelClientXRef = useRef<number | null>(null);
+
+	// Prevent browser zoom when pinching over the flamegraph
+	useEffect(() => {
+		const onWheel = (e: WheelEvent): void => {
+			if (isOverFlamegraphRef.current && e.ctrlKey) {
+				e.preventDefault();
+			}
+		};
+
+		window.addEventListener('wheel', onWheel, { passive: false, capture: true });
+
+		return (): void => {
+			window.removeEventListener('wheel', onWheel, {
+				capture: true,
+			} as EventListenerOptions);
+		};
+	}, []);
+
+	const applyWheelZoom = useCallback(() => {
+		rafRef.current = null;
+
+		const cssWidth = lastCssWidthRef.current || 1;
+		const cursorX = lastCursorXRef.current;
+		const fullSpanMs = traceMetadata.endTime - traceMetadata.startTime;
+
+		const oldStart = viewStartRef.current;
+		const oldEnd = viewEndRef.current;
+		const oldSpan = oldEnd - oldStart;
+
+		const deltaY = wheelDeltaRef.current;
+		wheelDeltaRef.current = 0;
+		if (deltaY === 0) {
+			return;
+		}
+
+		const zoomH = lastIsPinchRef.current
+			? PINCH_ZOOM_INTENSITY_H
+			: SCROLL_ZOOM_INTENSITY_H;
+		const zoomV = lastIsPinchRef.current
+			? PINCH_ZOOM_INTENSITY_V
+			: SCROLL_ZOOM_INTENSITY_V;
+
+		const factorH = Math.exp(deltaY * zoomH);
+		const factorV = Math.exp(deltaY * zoomV);
+
+		// --- Horizontal zoom ---
+		const desiredSpan = oldSpan * factorH;
+		const minSpanMs = Math.max(
+			MIN_VISIBLE_SPAN_MS,
+			oldSpan / Math.max(cssWidth, 1),
+		);
+		const clampedSpan = clamp(desiredSpan, minSpanMs, fullSpanMs);
+
+		const cursorRatio = clamp(cursorX / cssWidth, 0, 1);
+		const anchorTs = oldStart + cursorRatio * oldSpan;
+
+		let nextStart = anchorTs - cursorRatio * clampedSpan;
+		nextStart = clamp(
+			nextStart,
+			traceMetadata.startTime,
+			traceMetadata.endTime - clampedSpan,
+		);
+		const nextEnd = nextStart + clampedSpan;
+
+		// --- Vertical zoom (row height) ---
+		const desiredRow = rowHeightRef.current * (1 / factorV);
+		const nextRow = clamp(desiredRow, MIN_ROW_HEIGHT, MAX_ROW_HEIGHT);
+
+		// Write refs immediately so rapid wheel events read fresh values
+		viewStartRef.current = nextStart;
+		viewEndRef.current = nextEnd;
+		rowHeightRef.current = nextRow;
+
+		setViewStartTs(nextStart);
+		setViewEndTs(nextEnd);
+		setRowHeight(nextRow);
+	}, [
+		traceMetadata,
+		viewStartRef,
+		viewEndRef,
+		rowHeightRef,
+		setViewStartTs,
+		setViewEndTs,
+		setRowHeight,
+	]);
+
+	// Native wheel listener on the canvas (passive: false for reliable preventDefault)
+	useEffect(() => {
+		const canvas = canvasRef.current;
+		if (!canvas) {
+			return (): void => {};
+		}
+
+		const onWheel = (e: WheelEvent): void => {
+			e.preventDefault();
+
+			const pointer = getCanvasPointer(canvasRef, e.clientX);
+			if (!pointer) {
+				return;
+			}
+
+			// Flush accumulated delta if cursor moved significantly
+			if (lastWheelClientXRef.current !== null) {
+				const moved = Math.abs(e.clientX - lastWheelClientXRef.current);
+				if (moved > 6) {
+					wheelDeltaRef.current = 0;
+				}
+			}
+			lastWheelClientXRef.current = e.clientX;
+
+			lastIsPinchRef.current = e.ctrlKey;
+			lastCssWidthRef.current = pointer.cssWidth;
+			lastCursorXRef.current = pointer.cssX;
+			wheelDeltaRef.current += e.deltaY;
+
+			if (rafRef.current == null) {
+				rafRef.current = requestAnimationFrame(applyWheelZoom);
+			}
+		};
+
+		canvas.addEventListener('wheel', onWheel, { passive: false });
+
+		return (): void => {
+			canvas.removeEventListener('wheel', onWheel);
+		};
+	}, [canvasRef, applyWheelZoom]);
+
+	const handleResetZoom = useCallback(() => {
+		viewStartRef.current = traceMetadata.startTime;
+		viewEndRef.current = traceMetadata.endTime;
+		rowHeightRef.current = DEFAULT_ROW_HEIGHT;
+
+		setViewStartTs(traceMetadata.startTime);
+		setViewEndTs(traceMetadata.endTime);
+		setRowHeight(DEFAULT_ROW_HEIGHT);
+	}, [
+		traceMetadata,
+		viewStartRef,
+		viewEndRef,
+		rowHeightRef,
+		setViewStartTs,
+		setViewEndTs,
+		setRowHeight,
+	]);
+
+	return { handleResetZoom, isOverFlamegraphRef };
+}

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/hooks/useScrollToSpan.ts

@@ -0,0 +1,118 @@
+import {
+	Dispatch,
+	MutableRefObject,
+	RefObject,
+	SetStateAction,
+	useEffect,
+} from 'react';
+import { FlamegraphSpan } from 'types/api/trace/getTraceFlamegraph';
+
+import { MIN_VISIBLE_SPAN_MS } from '../constants';
+import { ITraceMetadata } from '../types';
+import { clamp, findSpanById, getFlamegraphRowMetrics } from '../utils';
+
+interface UseScrollToSpanArgs {
+	firstSpanAtFetchLevel: string;
+	spans: FlamegraphSpan[][];
+	traceMetadata: ITraceMetadata;
+	containerRef: RefObject<HTMLDivElement>;
+	viewStartRef: MutableRefObject<number>;
+	viewEndRef: MutableRefObject<number>;
+	scrollTopRef: MutableRefObject<number>;
+	rowHeight: number;
+	setViewStartTs: Dispatch<SetStateAction<number>>;
+	setViewEndTs: Dispatch<SetStateAction<number>>;
+	setScrollTop: Dispatch<SetStateAction<number>>;
+}
+
+/**
+ * When firstSpanAtFetchLevel (from URL spanId) changes, scroll and zoom the
+ * flamegraph so the selected span is centered in view.
+ */
+export function useScrollToSpan(args: UseScrollToSpanArgs): void {
+	const {
+		firstSpanAtFetchLevel,
+		spans,
+		traceMetadata,
+		containerRef,
+		viewStartRef,
+		viewEndRef,
+		scrollTopRef,
+		rowHeight,
+		setViewStartTs,
+		setViewEndTs,
+		setScrollTop,
+	} = args;
+
+	useEffect(() => {
+		if (!firstSpanAtFetchLevel || spans.length === 0) {
+			return;
+		}
+
+		const result = findSpanById(spans, firstSpanAtFetchLevel);
+		if (!result) {
+			return;
+		}
+
+		const { span, levelIndex } = result;
+		const container = containerRef.current;
+		if (!container) {
+			return;
+		}
+
+		const metrics = getFlamegraphRowMetrics(rowHeight);
+		const viewportHeight = container.clientHeight;
+		const totalHeight = spans.length * metrics.ROW_HEIGHT;
+		const maxScroll = Math.max(0, totalHeight - viewportHeight);
+
+		// Vertical: center the span's row in the viewport
+		const targetScrollTop = clamp(
+			levelIndex * metrics.ROW_HEIGHT -
+				viewportHeight / 2 +
+				metrics.ROW_HEIGHT / 2,
+			0,
+			maxScroll,
+		);
+
+		// Horizontal: zoom to span with padding (2x span duration), center it
+		const spanStartMs = span.timestamp;
+		const spanEndMs = span.timestamp + span.durationNano / 1e6;
+		const spanDurationMs = spanEndMs - spanStartMs;
+		const spanCenterMs = (spanStartMs + spanEndMs) / 2;
+
+		const visibleWindowMs = Math.max(spanDurationMs * 2, MIN_VISIBLE_SPAN_MS);
+		const fullSpanMs = traceMetadata.endTime - traceMetadata.startTime;
+		const clampedWindow = clamp(visibleWindowMs, MIN_VISIBLE_SPAN_MS, fullSpanMs);
+
+		let targetViewStart = spanCenterMs - clampedWindow / 2;
+		let targetViewEnd = spanCenterMs + clampedWindow / 2;
+
+		targetViewStart = clamp(
+			targetViewStart,
+			traceMetadata.startTime,
+			traceMetadata.endTime - clampedWindow,
+		);
+		targetViewEnd = targetViewStart + clampedWindow;
+
+		// Apply immediately (instant jump)
+		viewStartRef.current = targetViewStart;
+		viewEndRef.current = targetViewEnd;
+		scrollTopRef.current = targetScrollTop;
+
+		setViewStartTs(targetViewStart);
+		setViewEndTs(targetViewEnd);
+		setScrollTop(targetScrollTop);
+	}, [
+		firstSpanAtFetchLevel,
+		spans,
+		traceMetadata,
+		containerRef,
+		viewStartRef,
+		viewEndRef,
+		scrollTopRef,
+		rowHeight,
+		setViewStartTs,
+		setViewEndTs,
+		setScrollTop,
+	]);
+}

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/hooks/useVisualLayoutWorker.ts

@@ -0,0 +1,98 @@
+import { useEffect, useRef, useState } from 'react';
+import { FlamegraphSpan } from 'types/api/trace/getTraceFlamegraph';
+
+import { computeVisualLayout, VisualLayout } from '../computeVisualLayout';
+import { LayoutWorkerResponse } from '../visualLayoutWorkerTypes';
+
+const EMPTY_LAYOUT: VisualLayout = {
+	visualRows: [],
+	spanToVisualRow: {},
+	connectors: [],
+	totalVisualRows: 0,
+};
+
+function computeLayoutOrEmpty(spans: FlamegraphSpan[][]): VisualLayout {
+	return spans.length ? computeVisualLayout(spans) : EMPTY_LAYOUT;
+}
+
+function createLayoutWorker(): Worker {
+	return new Worker(new URL('../visualLayout.worker.ts', import.meta.url), {
+		type: 'module',
+	});
+}
+
+export function useVisualLayoutWorker(
+	spans: FlamegraphSpan[][],
+): { layout: VisualLayout; isComputing: boolean } {
+	const [layout, setLayout] = useState<VisualLayout>(EMPTY_LAYOUT);
+	const [isComputing, setIsComputing] = useState(false);
+	const workerRef = useRef<Worker | null>(null);
+	const requestIdRef = useRef(0);
+	const fallbackRef = useRef(typeof Worker === 'undefined');
+
+	// Effect: post message to worker when spans change
+	useEffect(() => {
+		if (fallbackRef.current) {
+			setLayout(computeLayoutOrEmpty(spans));
+			return;
+		}
+
+		if (!workerRef.current) {
+			try {
+				workerRef.current = createLayoutWorker();
+			} catch {
+				fallbackRef.current = true;
+				setLayout(computeLayoutOrEmpty(spans));
+				return;
+			}
+		}
+
+		if (!spans.length) {
+			setLayout(EMPTY_LAYOUT);
+			return;
+		}
+
+		const currentId = ++requestIdRef.current;
+		setIsComputing(true);
+
+		const worker = workerRef.current;
+
+		const onMessage = (e: MessageEvent<LayoutWorkerResponse>): void => {
+			if (e.data.requestId !== requestIdRef.current) {
+				return;
+			}
+			if (e.data.type === 'result') {
+				setLayout(e.data.layout);
+			} else {
+				setLayout(computeVisualLayout(spans));
+			}
+			setIsComputing(false);
+		};
+
+		const onError = (): void => {
+			if (requestIdRef.current === currentId) {
+				setLayout(computeVisualLayout(spans));
+				setIsComputing(false);
+			}
+		};
+
+		worker.addEventListener('message', onMessage);
+		worker.addEventListener('error', onError);
+		worker.postMessage({ type: 'compute', requestId: currentId, spans });
+
+		return (): void => {
+			worker.removeEventListener('message', onMessage);
+			worker.removeEventListener('error', onError);
+		};
+	}, [spans]);
+
+	// Cleanup worker on unmount
+	useEffect(
+		() => (): void => {
+			workerRef.current?.terminate();
+		},
+		[],
+	);
+
+	return { layout, isComputing };
+}

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/types.ts

@@ -0,0 +1,32 @@
+import { Dispatch, SetStateAction } from 'react';
+import { Event, FlamegraphSpan } from 'types/api/trace/getTraceFlamegraph';
+
+export interface ITraceMetadata {
+	startTime: number;
+	endTime: number;
+}
+
+export interface FlamegraphCanvasProps {
+	spans: FlamegraphSpan[][];
+	firstSpanAtFetchLevel: string;
+	setFirstSpanAtFetchLevel: Dispatch<SetStateAction<string>>;
+	onSpanClick: (spanId: string) => void;
+	traceMetadata: ITraceMetadata;
+}
+
+export interface SpanRect {
+	span: FlamegraphSpan;
+	x: number;
+	y: number;
+	width: number;
+	height: number;
+	level: number;
+}
+
+export interface EventRect {
+	event: Event;
+	span: FlamegraphSpan;
+	cx: number;
+	cy: number;
+	halfSize: number;
+}

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/utils.ts

@@ -0,0 +1,424 @@
+import { themeColors } from 'constants/theme';
+import { convertTimeToRelevantUnit } from 'container/TraceDetail/utils';
+import { generateColor } from 'lib/uPlotLib/utils/generateColor';
+import { FlamegraphSpan } from 'types/api/trace/getTraceFlamegraph';
+
+import {
+	DASHED_BORDER_LINE_DASH,
+	EVENT_DOT_SIZE_RATIO,
+	LABEL_FONT,
+	LABEL_PADDING_X,
+	MAX_EVENT_DOT_SIZE,
+	MAX_SPAN_BAR_HEIGHT,
+	MIN_EVENT_DOT_SIZE,
+	MIN_SPAN_BAR_HEIGHT,
+	MIN_WIDTH_FOR_NAME,
+	MIN_WIDTH_FOR_NAME_AND_DURATION,
+	SPAN_BAR_HEIGHT_RATIO,
+} from './constants';
+import { EventRect, SpanRect } from './types';
+
+export function clamp(v: number, min: number, max: number): number {
+	return Math.max(min, Math.min(max, v));
+}
+
+/** Create diagonal stripe pattern for selected/hovered span (repeating-linear-gradient -45deg style). */
+function createStripePattern(
+	ctx: CanvasRenderingContext2D,
+	color: string,
+): CanvasPattern | null {
+	const size = 20;
+	const patternCanvas = document.createElement('canvas');
+	patternCanvas.width = size;
+	patternCanvas.height = size;
+	const pCtx = patternCanvas.getContext('2d');
+	if (!pCtx) {
+		return null;
+	}
+
+	// Diagonal stripes at -45deg: 10px transparent, 10px colored (0.04 opacity), repeat
+	pCtx.globalAlpha = 0.04;
+	pCtx.strokeStyle = color;
+	pCtx.lineWidth = 10;
+	pCtx.lineCap = 'butt';
+	for (let i = -size; i < size * 2; i += size) {
+		pCtx.beginPath();
+		pCtx.moveTo(i + size, 0);
+		pCtx.lineTo(i, size);
+		pCtx.stroke();
+	}
+	pCtx.globalAlpha = 1;
+
+	return ctx.createPattern(patternCanvas, 'repeat');
+}
+
+export function findSpanById(
+	spans: FlamegraphSpan[][],
+	spanId: string,
+): { span: FlamegraphSpan; levelIndex: number } | null {
+	for (let levelIndex = 0; levelIndex < spans.length; levelIndex++) {
+		const span = spans[levelIndex]?.find((s) => s.spanId === spanId);
+		if (span) {
+			return { span, levelIndex };
+		}
+	}
+	return null;
+}
+
+export interface FlamegraphRowMetrics {
+	ROW_HEIGHT: number;
+	SPAN_BAR_HEIGHT: number;
+	SPAN_BAR_Y_OFFSET: number;
+	EVENT_DOT_SIZE: number;
+}
+
+export function getFlamegraphRowMetrics(
+	rowHeight: number,
+): FlamegraphRowMetrics {
+	const spanBarHeight = clamp(
+		Math.round(rowHeight * SPAN_BAR_HEIGHT_RATIO),
+		MIN_SPAN_BAR_HEIGHT,
+		MAX_SPAN_BAR_HEIGHT,
+	);
+	const spanBarYOffset = Math.floor((rowHeight - spanBarHeight) / 2);
+	const eventDotSize = clamp(
+		Math.round(spanBarHeight * EVENT_DOT_SIZE_RATIO),
+		MIN_EVENT_DOT_SIZE,
+		MAX_EVENT_DOT_SIZE,
+	);
+
+	return {
+		ROW_HEIGHT: rowHeight,
+		SPAN_BAR_HEIGHT: spanBarHeight,
+		SPAN_BAR_Y_OFFSET: spanBarYOffset,
+		EVENT_DOT_SIZE: eventDotSize,
+	};
+}
+
+interface GetSpanColorArgs {
+	span: FlamegraphSpan;
+	isDarkMode: boolean;
+}
+
+export function getSpanColor(args: GetSpanColorArgs): string {
+	const { span, isDarkMode } = args;
+	let color = generateColor(span.serviceName, themeColors.traceDetailColorsV3);
+
+	if (span.hasError) {
+		color = isDarkMode ? 'rgb(239, 68, 68)' : 'rgb(220, 38, 38)';
+	}
+
+	return color;
+}
+
+export interface EventDotColor {
+	fill: string;
+	stroke: string;
+}
+
+/** Derive event dot colors from parent span color. Error events always use red. */
+export function getEventDotColor(
+	spanColor: string,
+	isError: boolean,
+	isDarkMode: boolean,
+): EventDotColor {
+	if (isError) {
+		return {
+			fill: isDarkMode ? 'rgb(239, 68, 68)' : 'rgb(220, 38, 38)',
+			stroke: isDarkMode ? 'rgb(185, 28, 28)' : 'rgb(153, 27, 27)',
+		};
+	}
+
+	// Parse the span color (hex or rgb) to darken it for the event dot
+	let r: number | undefined;
+	let g: number | undefined;
+	let b: number | undefined;
+
+	const rgbMatch = spanColor.match(
+		/rgba?\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*(?:,\s*[\d.]+)?\s*\)/,
+	);
+	const hexMatch = spanColor.match(
+		/^#([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})$/i,
+	);
+
+	if (rgbMatch) {
+		r = parseInt(rgbMatch[1], 10);
+		g = parseInt(rgbMatch[2], 10);
+		b = parseInt(rgbMatch[3], 10);
+	} else if (hexMatch) {
+		r = parseInt(hexMatch[1], 16);
+		g = parseInt(hexMatch[2], 16);
+		b = parseInt(hexMatch[3], 16);
+	}
+
+	if (r !== undefined && g !== undefined && b !== undefined) {
+		// Darken by 20% for fill, 40% for stroke
+		const darken = (v: number, factor: number): number =>
+			Math.round(v * (1 - factor));
+		return {
+			fill: `rgb(${darken(r, 0.2)}, ${darken(g, 0.2)}, ${darken(b, 0.2)})`,
+			stroke: `rgb(${darken(r, 0.4)}, ${darken(g, 0.4)}, ${darken(b, 0.4)})`,
+		};
+	}
+
+	// Fallback to original cyan/blue
+	return {
+		fill: isDarkMode ? 'rgb(14, 165, 233)' : 'rgb(6, 182, 212)',
+		stroke: isDarkMode ? 'rgb(2, 132, 199)' : 'rgb(8, 145, 178)',
+	};
+}
+
+interface DrawEventDotArgs {
+	ctx: CanvasRenderingContext2D;
+	x: number;
+	y: number;
+	color: EventDotColor;
+	eventDotSize: number;
+}
+
+export function drawEventDot(args: DrawEventDotArgs): void {
+	const { ctx, x, y, color, eventDotSize } = args;
+
+	ctx.save();
+	ctx.translate(x, y);
+	ctx.rotate(Math.PI / 4);
+
+	ctx.fillStyle = color.fill;
+	ctx.strokeStyle = color.stroke;
+
+	ctx.lineWidth = 1;
+	const half = eventDotSize / 2;
+	ctx.fillRect(-half, -half, eventDotSize, eventDotSize);
+	ctx.strokeRect(-half, -half, eventDotSize, eventDotSize);
+	ctx.restore();
+}
+
+interface DrawSpanBarArgs {
+	ctx: CanvasRenderingContext2D;
+	span: FlamegraphSpan;
+	x: number;
+	y: number;
+	width: number;
+	levelIndex: number;
+	spanRectsArray: SpanRect[];
+	eventRectsArray: EventRect[];
+	color: string;
+	isDarkMode: boolean;
+	metrics: FlamegraphRowMetrics;
+	selectedSpanId?: string | null;
+	hoveredSpanId?: string | null;
+	hoveredEventKey?: string | null;
+}
+
+export function drawSpanBar(args: DrawSpanBarArgs): void {
+	const {
+		ctx,
+		span,
+		x,
+		y,
+		width,
+		levelIndex,
+		spanRectsArray,
+		eventRectsArray,
+		color,
+		isDarkMode,
+		metrics,
+		selectedSpanId,
+		hoveredSpanId,
+		hoveredEventKey,
+	} = args;
+
+	const spanY = y + metrics.SPAN_BAR_Y_OFFSET;
+	const isSelected = selectedSpanId === span.spanId;
+	const isHovered = hoveredSpanId === span.spanId;
+	const isSelectedOrHovered = isSelected || isHovered;
+
+	ctx.beginPath();
+	ctx.roundRect(x, spanY, width, metrics.SPAN_BAR_HEIGHT, 2);
+
+	if (isSelectedOrHovered) {
+		// Diagonal stripe pattern (repeating-linear-gradient -45deg style) + border in span color
+		const pattern = createStripePattern(ctx, color);
+		if (pattern) {
+			ctx.fillStyle = pattern;
+			ctx.fill();
+		}
+		if (isSelected) {
+			ctx.setLineDash(DASHED_BORDER_LINE_DASH);
+		}
+		ctx.strokeStyle = color;
+		ctx.lineWidth = isSelected ? 2 : 1;
+		ctx.stroke();
+		if (isSelected) {
+			ctx.setLineDash([]);
+		}
+	} else {
+		ctx.fillStyle = color;
+		ctx.fill();
+	}
+
+	spanRectsArray.push({
+		span,
+		x,
+		y: spanY,
+		width,
+		height: metrics.SPAN_BAR_HEIGHT,
+		level: levelIndex,
+	});
+
+	span.event?.forEach((event) => {
+		const spanDurationMs = span.durationNano / 1e6;
+		if (spanDurationMs <= 0) {
+			return;
+		}
+
+		const eventTimeMs = event.timeUnixNano / 1e6;
+		const eventOffsetPercent =
+			((eventTimeMs - span.timestamp) / spanDurationMs) * 100;
+		const clampedOffset = clamp(eventOffsetPercent, 1, 99);
+		const eventX = x + (clampedOffset / 100) * width;
+		const eventY = spanY + metrics.SPAN_BAR_HEIGHT / 2;
+
+		const dotColor = getEventDotColor(color, event.isError, isDarkMode);
+		const eventKey = `${span.spanId}-${event.name}-${event.timeUnixNano}`;
+		const isEventHovered = hoveredEventKey === eventKey;
+		const dotSize = isEventHovered
+			? Math.round(metrics.EVENT_DOT_SIZE * 1.5)
+			: metrics.EVENT_DOT_SIZE;
+
+		drawEventDot({
+			ctx,
+			x: eventX,
+			y: eventY,
+			color: dotColor,
+			eventDotSize: dotSize,
+		});
+
+		eventRectsArray.push({
+			event,
+			span,
+			cx: eventX,
+			cy: eventY,
+			halfSize: metrics.EVENT_DOT_SIZE / 2,
+		});
+	});
+
+	drawSpanLabel({
+		ctx,
+		span,
+		x,
+		y: spanY,
+		width,
+		color,
+		isSelectedOrHovered,
+		isDarkMode,
+		spanBarHeight: metrics.SPAN_BAR_HEIGHT,
+	});
+}
+
+export function formatDuration(durationNano: number): string {
+	const durationMs = durationNano / 1e6;
+	const { time, timeUnitName } = convertTimeToRelevantUnit(durationMs);
+	return `${parseFloat(time.toFixed(2))}${timeUnitName}`;
+}
+
+interface DrawSpanLabelArgs {
+	ctx: CanvasRenderingContext2D;
+	span: FlamegraphSpan;
+	x: number;
+	y: number;
+	width: number;
+	color: string;
+	isSelectedOrHovered: boolean;
+	isDarkMode: boolean;
+	spanBarHeight: number;
+}
+
+function drawSpanLabel(args: DrawSpanLabelArgs): void {
+	const {
+		ctx,
+		span,
+		x,
+		y,
+		width,
+		color,
+		isSelectedOrHovered,
+		isDarkMode,
+		spanBarHeight,
+	} = args;
+
+	if (width < MIN_WIDTH_FOR_NAME) {
+		return;
+	}
+
+	const name = span.name;
+
+	ctx.save();
+
+	// Clip text to span bar bounds
+	ctx.beginPath();
+	ctx.rect(x, y, width, spanBarHeight);
+	ctx.clip();
+
+	ctx.font = LABEL_FONT;
+	ctx.fillStyle = isSelectedOrHovered
+		? color
+		: isDarkMode
+		? 'rgba(0, 0, 0, 0.9)'
+		: 'rgba(255, 255, 255, 0.9)';
+	ctx.textBaseline = 'middle';
+
+	const textY = y + spanBarHeight / 2;
+	const leftX = x + LABEL_PADDING_X;
+	const rightX = x + width - LABEL_PADDING_X;
+	const availableWidth = width - LABEL_PADDING_X * 2;
+
+	if (width >= MIN_WIDTH_FOR_NAME_AND_DURATION) {
+		const duration = formatDuration(span.durationNano);
+		const durationWidth = ctx.measureText(duration).width;
+		const minGap = 6;
+		const nameSpace = availableWidth - durationWidth - minGap;
+
+		// Duration right-aligned
+		ctx.textAlign = 'right';
+		ctx.fillText(duration, rightX, textY);
+
+		// Name left-aligned, truncated to fit remaining space
+		if (nameSpace > 20) {
+			ctx.textAlign = 'left';
+			ctx.fillText(truncateText(ctx, name, nameSpace), leftX, textY);
+		}
+	} else {
+		// Name only, truncated to fit
+		ctx.textAlign = 'left';
+		ctx.fillText(truncateText(ctx, name, availableWidth), leftX, textY);
+	}
+
+	ctx.restore();
+}
+
+function truncateText(
+	ctx: CanvasRenderingContext2D,
+	text: string,
+	maxWidth: number,
+): string {
+	const ellipsis = '...';
+	const ellipsisWidth = ctx.measureText(ellipsis).width;
+
+	if (ctx.measureText(text).width <= maxWidth) {
+		return text;
+	}
+
+	let lo = 0;
+	let hi = text.length;
+	while (lo < hi) {
+		const mid = Math.ceil((lo + hi) / 2);
+		if (ctx.measureText(text.slice(0, mid)).width + ellipsisWidth <= maxWidth) {
+			lo = mid;
+		} else {
+			hi = mid - 1;
+		}
+	}
+
+	return lo > 0 ? `${text.slice(0, lo)}${ellipsis}` : ellipsis;
+}

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/visualLayout.worker.ts

@@ -0,0 +1,26 @@
+/// <reference lib="webworker" />
+import { computeVisualLayout } from './computeVisualLayout';
+import {
+	LayoutWorkerRequest,
+	LayoutWorkerResponse,
+} from './visualLayoutWorkerTypes';
+
+self.onmessage = (event: MessageEvent<LayoutWorkerRequest>): void => {
+	const { requestId, spans } = event.data;
+	try {
+		const layout = computeVisualLayout(spans);
+		const response: LayoutWorkerResponse = {
+			type: 'result',
+			requestId,
+			layout,
+		};
+		self.postMessage(response);
+	} catch (err) {
+		const response: LayoutWorkerResponse = {
+			type: 'error',
+			requestId,
+			message: String(err),
+		};
+		self.postMessage(response);
+	}
+};

frontend/src/pages/TraceDetailsV3/TraceFlamegraph/visualLayoutWorkerTypes.ts

@@ -0,0 +1,13 @@
+import { FlamegraphSpan } from 'types/api/trace/getTraceFlamegraph';
+
+import { VisualLayout } from './computeVisualLayout';
+
+export interface LayoutWorkerRequest {
+	type: 'compute';
+	requestId: number;
+	spans: FlamegraphSpan[][];
+}
+
+export type LayoutWorkerResponse =
+	| { type: 'result'; requestId: number; layout: VisualLayout }
+	| { type: 'error'; requestId: number; message: string };

frontend/src/types/api/trace/getTraceFlamegraph.ts

@@ -4,7 +4,8 @@ export interface TraceDetailFlamegraphURLProps {
 
 export interface GetTraceFlamegraphPayloadProps {
 	traceId: string;
-	selectedSpanId: string;
+	selectedSpanId?: string;
+	limit?: number;
 }
 
 export interface Event {

pkg/auditor/config.go

@@ -63,6 +63,7 @@ type RetryConfig struct {
 
 func newConfig() factory.Config {
 	return Config{
+		Provider:      "noop",
 		BufferSize:    1000,
 		BatchSize:     100,
 		FlushInterval: time.Second,

pkg/query-service/app/server.go

@@ -208,7 +208,7 @@ func (s *Server) createPublicServer(api *APIHandler, web web.Web) (*http.Server,
 		s.config.APIServer.Timeout.Default,
 		s.config.APIServer.Timeout.Max,
 	).Wrap)
-	r.Use(middleware.NewAudit(s.signoz.Instrumentation.Logger(), s.config.APIServer.Logging.ExcludedRoutes, nil).Wrap)
+	r.Use(middleware.NewAudit(s.signoz.Instrumentation.Logger(), s.config.APIServer.Logging.ExcludedRoutes, s.signoz.Auditor).Wrap)
 	r.Use(middleware.NewComment().Wrap)
 
 	am := middleware.NewAuthZ(s.signoz.Instrumentation.Logger(), s.signoz.Modules.OrgGetter, s.signoz.Authz)

pkg/signoz/config.go

@@ -11,6 +11,7 @@ import (
 	"github.com/SigNoz/signoz/pkg/alertmanager"
 	"github.com/SigNoz/signoz/pkg/analytics"
 	"github.com/SigNoz/signoz/pkg/apiserver"
+	"github.com/SigNoz/signoz/pkg/auditor"
 	"github.com/SigNoz/signoz/pkg/cache"
 	"github.com/SigNoz/signoz/pkg/config"
 	"github.com/SigNoz/signoz/pkg/emailing"
@@ -123,6 +124,9 @@ type Config struct {
 
 	// ServiceAccount config
 	ServiceAccount serviceaccount.Config `mapstructure:"serviceaccount"`
+
+	// Auditor config
+	Auditor auditor.Config `mapstructure:"auditor"`
 }
 
 func NewConfig(ctx context.Context, logger *slog.Logger, resolverConfig config.ResolverConfig) (Config, error) {
@@ -153,6 +157,7 @@ func NewConfig(ctx context.Context, logger *slog.Logger, resolverConfig config.R
 		user.NewConfigFactory(),
 		identn.NewConfigFactory(),
 		serviceaccount.NewConfigFactory(),
+		auditor.NewConfigFactory(),
 	}
 
 	conf, err := config.New(ctx, resolverConfig, configFactories)

pkg/signoz/provider.go

@@ -3,6 +3,8 @@ package signoz
 import (
 	"github.com/SigNoz/signoz/pkg/alertmanager"
 	"github.com/SigNoz/signoz/pkg/alertmanager/nfmanager"
+	"github.com/SigNoz/signoz/pkg/auditor"
+	"github.com/SigNoz/signoz/pkg/auditor/noopauditor"
 	"github.com/SigNoz/signoz/pkg/alertmanager/nfmanager/rulebasednotification"
 	"github.com/SigNoz/signoz/pkg/alertmanager/signozalertmanager"
 	"github.com/SigNoz/signoz/pkg/analytics"
@@ -312,6 +314,12 @@ func NewGlobalProviderFactories(identNConfig identn.Config) factory.NamedMap[fac
 	)
 }
 
+func NewAuditorProviderFactories() factory.NamedMap[factory.ProviderFactory[auditor.Auditor, auditor.Config]] {
+	return factory.MustNewNamedMap(
+		noopauditor.NewFactory(),
+	)
+}
+
 func NewFlaggerProviderFactories(registry featuretypes.Registry) factory.NamedMap[factory.ProviderFactory[flagger.FlaggerProvider, flagger.Config]] {
 	return factory.MustNewNamedMap(
 		configflagger.NewFactory(registry),

pkg/signoz/signoz.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/SigNoz/signoz/pkg/alertmanager"
 	"github.com/SigNoz/signoz/pkg/alertmanager/nfmanager"
+	"github.com/SigNoz/signoz/pkg/auditor"
 	"github.com/SigNoz/signoz/pkg/alertmanager/nfmanager/nfroutingstore/sqlroutingstore"
 	"github.com/SigNoz/signoz/pkg/analytics"
 	"github.com/SigNoz/signoz/pkg/apiserver"
@@ -75,6 +76,7 @@ type SigNoz struct {
 	QueryParser            queryparser.QueryParser
 	Flagger                flagger.Flagger
 	Gateway                gateway.Gateway
+	Auditor                auditor.Auditor
 }
 
 func New(
@@ -94,6 +96,7 @@ func New(
 	authzCallback func(context.Context, sqlstore.SQLStore, licensing.Licensing, dashboard.Module) (factory.ProviderFactory[authz.AuthZ, authz.Config], error),
 	dashboardModuleCallback func(sqlstore.SQLStore, factory.ProviderSettings, analytics.Analytics, organization.Getter, queryparser.QueryParser, querier.Querier, licensing.Licensing) dashboard.Module,
 	gatewayProviderFactory func(licensing.Licensing) factory.ProviderFactory[gateway.Gateway, gateway.Config],
+	auditorProviderFactories func(licensing.Licensing) factory.NamedMap[factory.ProviderFactory[auditor.Auditor, auditor.Config]],
 	querierHandlerCallback func(factory.ProviderSettings, querier.Querier, analytics.Analytics) querier.Handler,
 ) (*SigNoz, error) {
 	// Initialize instrumentation
@@ -371,6 +374,12 @@ func New(
 		return nil, err
 	}
 
+	// Initialize auditor from the variant-specific provider factories
+	auditor, err := factory.NewProviderFromNamedMap(ctx, providerSettings, config.Auditor, auditorProviderFactories(licensing), config.Auditor.Provider)
+	if err != nil {
+		return nil, err
+	}
+
 	// Initialize authns
 	store := sqlauthnstore.NewStore(sqlstore)
 	authNs, err := authNsCallback(ctx, providerSettings, store, licensing)
@@ -470,6 +479,7 @@ func New(
 		factory.NewNamedService(factory.MustNewName("tokenizer"), tokenizer),
 		factory.NewNamedService(factory.MustNewName("authz"), authz),
 		factory.NewNamedService(factory.MustNewName("user"), userService, factory.MustNewName("authz")),
+		factory.NewNamedService(factory.MustNewName("auditor"), auditor),
 	)
 	if err != nil {
 		return nil, err
@@ -516,5 +526,6 @@ func New(
 		QueryParser:            queryParser,
 		Flagger:                flagger,
 		Gateway:                gateway,
+		Auditor:                auditor,
 	}, nil
 }