fix(trace-waterfall): soften row-action button gradient

frontend/src/pages/TraceDetailsV3/TraceDetailsHeader/MissingSpansBanner.module.scss

@@ -0,0 +1,25 @@
+.container {
+	// Gutter matches the header/subHeader 16px; bottom gap before the panels.
+	padding: 0 16px 12px;
+}
+
+.title {
+	display: flex;
+	align-items: center;
+	justify-content: space-between;
+	gap: 8px;
+	width: 100%;
+}
+
+.link {
+	display: inline-flex;
+	align-items: center;
+	gap: 4px;
+	color: inherit;
+	font-weight: 500;
+	white-space: nowrap;
+
+	&:hover {
+		opacity: 0.85;
+	}
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsHeader/MissingSpansBanner.tsx

@@ -0,0 +1,47 @@
+import { useState } from 'react';
+import { Callout } from '@signozhq/ui/callout';
+import { ArrowUpRight } from '@signozhq/icons';
+
+import styles from './MissingSpansBanner.module.scss';
+
+const MISSING_SPANS_DOCS_URL =
+	'https://signoz.io/docs/userguide/traces/#missing-spans';
+
+function MissingSpansBanner(): JSX.Element | null {
+	// Session-only dismissal — not persisted, so the banner returns on reload.
+	const [isDismissed, setIsDismissed] = useState(false);
+
+	if (isDismissed) {
+		return null;
+	}
+
+	// Wrapper owns the gutter: Callout is width:100%, so putting the gutter as a
+	// margin on it would overflow the parent by the margin width. Pad instead.
+	return (
+		<div className={styles.container}>
+			<Callout
+				type="info"
+				size="small"
+				showIcon
+				action="dismissible"
+				onClick={(): void => setIsDismissed(true)}
+				testId="missing-spans-banner"
+				title={
+					<span className={styles.title}>
+						This trace has missing spans
+						<a
+							className={styles.link}
+							href={MISSING_SPANS_DOCS_URL}
+							target="_blank"
+							rel="noopener noreferrer"
+						>
+							Learn More <ArrowUpRight size={14} />
+						</a>
+					</span>
+				}
+			/>
+		</div>
+	);
+}
+
+export default MissingSpansBanner;

frontend/src/pages/TraceDetailsV3/TraceDetailsHeader/TraceDetailsHeader.tsx

@@ -31,6 +31,7 @@ import { useTraceDetailLogEvent } from '../hooks/useTraceDetailLogEvent';
 import { useTraceStore } from '../stores/traceStore';
 import AnalyticsPanel from '../SpanDetailsPanel/AnalyticsPanel/AnalyticsPanel';
 import Filters from '../TraceWaterfall/TraceWaterfallStates/Success/Filters/Filters';
+import MissingSpansBanner from './MissingSpansBanner';
 import TraceOptionsMenu from './TraceOptionsMenu';
 
 import styles from './TraceDetailsHeader.module.scss';
@@ -48,6 +49,7 @@ export interface TraceMetadataForHeader {
 	rootServiceName: string;
 	rootServiceEntryPoint: string;
 	rootSpanStatusCode: string;
+	hasMissingSpans: boolean;
 }
 
 interface TraceDetailsHeaderProps {
@@ -229,6 +231,8 @@ function TraceDetailsHeader({
 				</div>
 			)}
 
+			{traceMetadata?.hasMissingSpans && <MissingSpansBanner />}
+
 			<FieldsSelector
 				isOpen={isPreviewFieldsOpen}
 				title="Preview fields"

frontend/src/pages/TraceDetailsV3/TraceDetailsV3.module.scss

@@ -41,6 +41,7 @@
 	:global(.ant-collapse-header) {
 		border-top: 1px solid var(--l2-border);
 		border-bottom: 1px solid var(--l2-border);
+		border-radius: 0 !important;
 	}
 
 	:global(.ant-collapse-content) {
@@ -98,6 +99,13 @@
 	flex-direction: column;
 	overflow: hidden;
 
+	// The flamegraph's ResizableBox above renders a 1px resize handle at its
+	// bottom edge; drop the header's own top border so the two don't stack
+	// into a double border at the flamegraph/waterfall juncture.
+	:global(.ant-collapse-header) {
+		border-top: none;
+	}
+
 	:global(.ant-collapse-item) {
 		flex: 1;
 		display: flex;

frontend/src/pages/TraceDetailsV3/TraceWaterfall/TraceWaterfallStates/Success/Success.module.scss

@@ -49,59 +49,6 @@
 	flex-direction: column;
 }
 
-.missingSpans {
-	display: flex;
-	align-items: center;
-	justify-content: space-between;
-	height: 44px;
-	margin: 16px;
-	padding: 12px;
-	border-radius: 4px;
-	background: rgba(69, 104, 220, 0.1);
-}
-
-.leftInfo {
-	display: flex;
-	align-items: center;
-	gap: 8px;
-	color: var(--bg-robin-400);
-	font-family: Inter;
-	font-size: 14px;
-	font-style: normal;
-	font-weight: 400;
-	line-height: 20px;
-	letter-spacing: -0.07px;
-}
-
-.text {
-	color: var(--bg-robin-400);
-	font-family: Inter;
-	font-size: 14px;
-	font-style: normal;
-	font-weight: 400;
-	line-height: 20px;
-	letter-spacing: -0.07px;
-}
-
-.rightInfo {
-	display: flex;
-	align-items: center;
-	justify-content: center;
-	gap: 8px;
-	color: var(--bg-robin-400);
-	font-family: Inter;
-	font-size: 14px;
-	font-style: normal;
-	font-weight: 400;
-	line-height: 20px;
-	letter-spacing: -0.07px;
-
-	&:hover {
-		background-color: unset;
-		color: var(--bg-robin-200);
-	}
-}
-
 .splitPanel {
 	flex: 1;
 	min-height: 0;
@@ -216,10 +163,12 @@
 
 .treeRow:hover,
 .treeRow.hoveredSpan {
-	border-radius: 4px;
+	// Left end of the row band — round only the outer (left) corners so the
+	// highlight joins the status + timeline segments into one continuous band.
+	border-radius: 4px 0 0 4px;
 	background: color-mix(
 		in srgb,
-		var(--l3-background) 20%,
+		var(--l3-background) 60%,
 		transparent
 	) !important;
 
@@ -262,20 +211,22 @@
 	--badge-border-width: 0px;
 
 	&.hoveredSpan {
-		border-radius: 4px;
+		// Middle segment of the row band — square so it butts up against the
+		// name and timeline segments (no rounded corner at the badge column).
+		border-radius: 0;
 		background: color-mix(
 			in srgb,
-			var(--l3-background) 20%,
+			var(--l3-background) 60%,
 			transparent
 		) !important;
 	}
 
 	&.isInterested,
 	&.isSelectedNonMatching {
-		border-radius: 4px;
+		border-radius: 0;
 		background: color-mix(
 			in srgb,
-			var(--l3-background) 40%,
+			var(--l3-background) 80%,
 			transparent
 		) !important;
 	}
@@ -309,20 +260,21 @@
 
 	&:hover,
 	&.hoveredSpan {
-		border-radius: 4px;
+		// Right end of the row band — round only the outer (right) corners.
+		border-radius: 0 4px 4px 0;
 		background: color-mix(
 			in srgb,
-			var(--l3-background) 20%,
+			var(--l3-background) 60%,
 			transparent
 		) !important;
 	}
 
 	&:has(.isInterested),
 	&:has(.isSelectedNonMatching) {
-		border-radius: 4px;
+		border-radius: 0 4px 4px 0;
 		background: color-mix(
 			in srgb,
-			var(--l3-background) 40%,
+			var(--l3-background) 80%,
 			transparent
 		) !important;
 	}
@@ -345,10 +297,11 @@
 
 	&.isInterested,
 	&.isSelectedNonMatching {
-		border-radius: 4px;
+		// Left end of the row band — outer (left) corners only.
+		border-radius: 4px 0 0 4px;
 		background: color-mix(
 			in srgb,
-			var(--l3-background) 40%,
+			var(--l3-background) 80%,
 			transparent
 		) !important;
 	}
@@ -471,7 +424,7 @@
 	padding-left: 8px;
 	flex-shrink: 0;
 	height: 100%;
-	background: linear-gradient(to left, var(--l1-background) 60%, transparent);
+	background: linear-gradient(to left, var(--l2-background) 40%, transparent);
 	z-index: 2;
 	opacity: 0;
 	pointer-events: none;
@@ -599,6 +552,18 @@
 	opacity: 0.15;
 }
 
+// A dimmed span must still show the full-opacity hover state when hovered.
+// These win over `.isDimmed` on specificity so brightness is restored across
+// the whole row (name column, status cell, and timeline bar) on hover.
+.treeRow:hover .isDimmed,
+.treeRow.hoveredSpan .isDimmed,
+.timelineRow:hover .isDimmed,
+.timelineRow.hoveredSpan .isDimmed,
+.statusCell:hover.isDimmed,
+.statusCell.hoveredSpan.isDimmed {
+	opacity: 1;
+}
+
 .isHighlighted {
 	opacity: 1;
 }

frontend/src/pages/TraceDetailsV3/TraceWaterfall/TraceWaterfallStates/Success/Success.tsx

@@ -33,14 +33,7 @@ import { useIsDarkMode } from 'hooks/useDarkMode';
 import { useSafeNavigate } from 'hooks/useSafeNavigate';
 import useUrlQuery from 'hooks/useUrlQuery';
 import { colorToRgb } from 'lib/uPlotLib/utils/generateColor';
-import {
-	ArrowUpRight,
-	ChevronDown,
-	ChevronRight,
-	CircleAlert,
-	Link,
-	ListPlus,
-} from '@signozhq/icons';
+import { ChevronDown, ChevronRight, Link, ListPlus } from '@signozhq/icons';
 import { useTraceStore } from 'pages/TraceDetailsV3/stores/traceStore';
 import { resolveSpanColor } from 'pages/TraceDetailsV3/utils';
 import { useBoundaryPagination } from 'pages/TraceDetailsV3/TraceWaterfall/hooks/useBoundaryPagination';
@@ -854,28 +847,6 @@ function Success(props: ISuccessProps): JSX.Element {
 
 	return (
 		<div className={styles.root}>
-			{traceMetadata.hasMissingSpans && (
-				<div className={styles.missingSpans}>
-					<section className={styles.leftInfo}>
-						<CircleAlert size={14} />
-						<span className={styles.text}>This trace has missing spans</span>
-					</section>
-					<Button
-						variant="ghost"
-						color="secondary"
-						className={styles.rightInfo}
-						suffix={<ArrowUpRight size={14} />}
-						onClick={(): WindowProxy | null =>
-							window.open(
-								'https://signoz.io/docs/userguide/traces/#missing-spans',
-								'_blank',
-							)
-						}
-					>
-						Learn More
-					</Button>
-				</div>
-			)}
 			{isFetching && <div className={styles.loadingBar} />}
 			<div className={styles.splitPanel} ref={scrollContainerRef}>
 				{/* Sticky header row */}
@@ -994,8 +965,8 @@ function Success(props: ISuccessProps): JSX.Element {
 										transform: `translateY(${virtualRow.start}px)`,
 									}}
 									data-span-id={span.span_id}
-									onMouseEnter={(): void => handleRowMouseEnter(span.span_id)}
-									onMouseLeave={handleRowMouseLeave}
+									onMouseEnter={(): void => applyHoverClass(span.span_id)}
+									onMouseLeave={(): void => applyHoverClass(null)}
 									onClick={(): void => handleSpanClick(span)}
 								>
 									{span.response_status_code && (

frontend/src/pages/TraceDetailsV3/index.tsx

@@ -1,7 +1,12 @@
 /* eslint-disable sonarjs/cognitive-complexity */
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import { useParams } from 'react-router-dom';
-import { ChartNoAxesGantt, TriangleAlert } from '@signozhq/icons';
+import {
+	ChartNoAxesGantt,
+	ChevronDown,
+	ChevronRight,
+	TriangleAlert,
+} from '@signozhq/icons';
 import getLocalStorageKey from 'api/browser/localstorage/get';
 import setLocalStorageKey from 'api/browser/localstorage/set';
 import { Collapse } from 'antd';
@@ -34,6 +39,16 @@ import cx from 'classnames';
 
 import styles from './TraceDetailsV3.module.scss';
 
+// Lucide chevrons for the flame/waterfall accordion headers, matching the
+// span-tree chevrons in the waterfall.
+function renderPanelExpandIcon({
+	isActive,
+}: {
+	isActive?: boolean;
+}): JSX.Element {
+	return isActive ? <ChevronDown size={14} /> : <ChevronRight size={14} />;
+}
+
 function TraceDetailsV3(): JSX.Element {
 	const { id: traceId } = useParams<TraceDetailV3URLProps>();
 	const urlQuery = useUrlQuery();
@@ -329,6 +344,7 @@ function TraceDetailsV3(): JSX.Element {
 			rootServiceName: payload.rootServiceName,
 			rootServiceEntryPoint: payload.rootServiceEntryPoint,
 			rootSpanStatusCode: rootSpan?.response_status_code || '',
+			hasMissingSpans: payload.hasMissingSpans || false,
 		};
 	}, [traceData?.payload]);
 
@@ -388,6 +404,7 @@ function TraceDetailsV3(): JSX.Element {
 									activeKey={activeKeys.filter((k) => k === 'flame')}
 									onChange={(): void => handleCollapseChange('flame')}
 									size="small"
+									expandIcon={renderPanelExpandIcon}
 									className={styles.flameCollapse}
 									items={[
 										{
@@ -442,6 +459,7 @@ function TraceDetailsV3(): JSX.Element {
 									activeKey={activeKeys.filter((k) => k === 'waterfall')}
 									onChange={(): void => handleCollapseChange('waterfall')}
 									size="small"
+									expandIcon={renderPanelExpandIcon}
 									className={cx(styles.waterfallCollapse, {
 										[styles.isDocked]: isWaterfallDocked,
 									})}