Merge branch 'feat/trace-details-thread-tab' into feat/trace-details-thread

# Conflicts:
#	frontend/src/pages/TraceDetailsV3/EntityMetadata/EntityMetadataRow.tsx
#	frontend/src/pages/TraceDetailsV3/EntityMetadata/TokenUsageTooltip.tsx
#	frontend/src/pages/TraceDetailsV3/SpanHoverCard/aiUsage.ts

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

@@ -0,0 +1,247 @@
+.message {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-4);
+	min-width: 0;
+}
+
+.roleHeader {
+	display: flex;
+	align-items: center;
+	gap: var(--spacing-4);
+	font-size: var(--font-size-xs);
+	font-weight: var(--font-weight-medium);
+	color: var(--l1-foreground);
+}
+
+.parts {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-4);
+	min-width: 0;
+}
+
+.empty {
+	font-size: var(--periscope-font-size-base);
+	font-style: italic;
+	color: var(--l2-foreground);
+}
+
+.textBox {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-3);
+	padding: var(--spacing-3) var(--spacing-5);
+	border: 1px solid var(--l2-border);
+	border-radius: var(--radius-2);
+	background: var(--l2-background);
+	min-width: 0;
+}
+
+.text {
+	font-size: var(--periscope-font-size-base);
+	line-height: var(--line-height-20);
+	color: var(--l1-foreground);
+	word-break: break-word;
+
+	:global(p) {
+		margin: 0 0 var(--spacing-4);
+	}
+
+	:global(p:last-child) {
+		margin-bottom: 0;
+	}
+
+	:global(ol),
+	:global(ul) {
+		margin: 0 0 var(--spacing-4);
+		padding-left: var(--spacing-10);
+	}
+}
+
+.plainText {
+	white-space: pre-wrap;
+}
+
+.showMore {
+	align-self: flex-start;
+	padding: 0;
+	border: none;
+	background: none;
+	font-size: var(--font-size-xs);
+	color: var(--primary);
+	cursor: pointer;
+}
+
+.chip {
+	display: inline-flex;
+	align-items: center;
+	gap: var(--spacing-3);
+	align-self: flex-start;
+	max-width: 100%;
+	padding: var(--spacing-2) var(--spacing-4);
+	border-radius: var(--radius-2);
+	background: var(--l2-background);
+	font-size: var(--font-size-xs);
+	color: var(--l1-foreground);
+	min-width: 0;
+}
+
+.dot {
+	flex-shrink: 0;
+	width: var(--spacing-3);
+	height: var(--spacing-3);
+	border-radius: var(--radius-round);
+
+	&[data-tone='success'] {
+		background: var(--accent-forest);
+	}
+
+	&[data-tone='warning'] {
+		background: var(--accent-amber);
+	}
+
+	&[data-tone='error'] {
+		background: var(--accent-cherry);
+	}
+}
+
+.chipLabel {
+	flex-shrink: 0;
+}
+
+.chipSeparator {
+	flex-shrink: 0;
+	color: var(--l2-foreground);
+}
+
+.chipValue {
+	display: inline-flex;
+	gap: var(--spacing-2);
+	overflow: hidden;
+	text-overflow: ellipsis;
+	white-space: nowrap;
+	min-width: 0;
+	color: var(--accent-primary);
+}
+
+.chipKey {
+	flex-shrink: 0;
+}
+
+.toolName {
+	overflow: hidden;
+	text-overflow: ellipsis;
+	color: var(--accent-amber);
+}
+
+.toolCall,
+.toolResult {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-3);
+	min-width: 0;
+}
+
+.toolCall {
+	border-radius: var(--radius-2);
+	transition: outline-color 0.3s ease;
+	outline: 1px solid transparent;
+	outline-offset: var(--spacing-1);
+
+	&.isHighlighted {
+		outline-color: var(--primary);
+	}
+}
+
+.toolLink {
+	display: inline-flex;
+	align-items: center;
+	flex-shrink: 0;
+	padding: 0;
+	border: none;
+	background: none;
+	color: var(--l2-foreground);
+	cursor: pointer;
+
+	&:hover:not(:disabled) {
+		color: var(--primary);
+	}
+
+	&:disabled {
+		cursor: not-allowed;
+		opacity: 0.5;
+	}
+}
+
+.collapsible {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-4);
+	min-width: 0;
+
+	&.boxed {
+		gap: 0;
+		border: 1px solid var(--l2-border);
+		border-radius: var(--radius-2);
+		background: var(--l2-background);
+
+		.collapsibleToggle {
+			justify-content: space-between;
+			padding: var(--spacing-3) var(--spacing-5);
+		}
+
+		.collapsibleBody {
+			padding: 0 var(--spacing-5) var(--spacing-4);
+		}
+	}
+}
+
+.collapsibleToggle {
+	display: flex;
+	align-items: center;
+	gap: var(--spacing-2);
+	min-width: 0;
+	padding: 0;
+	border: none;
+	background: none;
+	font-size: var(--font-size-xs);
+	color: var(--l2-foreground);
+	cursor: pointer;
+	text-align: left;
+}
+
+.collapsibleLabel {
+	font-weight: var(--font-weight-medium);
+	color: var(--l1-foreground);
+}
+
+.collapsibleBody {
+	display: flex;
+	flex-direction: column;
+	min-width: 0;
+}
+
+.json {
+	min-width: 0;
+	padding: var(--spacing-3) var(--spacing-4);
+	border: 1px solid var(--l2-border);
+	border-radius: var(--radius-2);
+	cursor: auto;
+
+	:global(.pretty-view) {
+		padding: 0;
+	}
+}
+
+.mediaChip {
+	display: inline-flex;
+	align-items: center;
+	gap: var(--spacing-3);
+	align-self: flex-start;
+	padding: var(--spacing-2) var(--spacing-4);
+	border: 1px solid var(--l2-border);
+	border-radius: var(--radius-round);
+	font-size: var(--font-size-xs);
+	color: var(--l2-foreground);
+}

frontend/src/pages/TraceDetailsV3/AIThreadMessage/AIThreadMessage.tsx

@@ -0,0 +1,89 @@
+import { Badge } from '@signozhq/ui/badge';
+
+import { ThreadMessage } from '../TraceDetailsThread/types';
+import CollapsibleBlock from './CollapsibleBlock';
+import MessagePart from './MessagePart';
+import PartChip from './PartChip';
+import { getFinishReasonTone, getRoleLabel } from './utils';
+
+import styles from './AIThreadMessage.module.scss';
+
+export interface AIThreadMessageProps {
+	message: ThreadMessage;
+	isOutput?: boolean;
+	isToolLinkEnabled?: (toolCallId: string) => boolean;
+	onToolLinkClick?: (toolCallId: string) => void;
+}
+
+function AIThreadMessage({
+	message,
+	isOutput,
+	isToolLinkEnabled,
+	onToolLinkClick,
+}: AIThreadMessageProps): JSX.Element {
+	const { role, content, finishReason } = message;
+	const roleLabel = getRoleLabel(role);
+	const tone = getFinishReasonTone(finishReason);
+
+	const parts = (
+		<div className={styles.parts}>
+			{content.length === 0 ? (
+				<span className={styles.empty}>No content</span>
+			) : (
+				content.map((part, index) => (
+					<MessagePart
+						// Parts have no stable id and never reorder.
+						// eslint-disable-next-line react/no-array-index-key
+						key={index}
+						part={part}
+						isToolLinkEnabled={isToolLinkEnabled}
+						onToolLinkClick={onToolLinkClick}
+					/>
+				))
+			)}
+		</div>
+	);
+
+	return (
+		<div
+			className={styles.message}
+			data-testid={`ai-thread-message-${role || 'unknown'}`}
+		>
+			{role === 'system' ? (
+				<CollapsibleBlock label={roleLabel} testId="ai-message-system-toggle">
+					{parts}
+				</CollapsibleBlock>
+			) : (
+				<>
+					{roleLabel && (
+						<div className={styles.roleHeader}>
+							{roleLabel}
+							{isOutput && (
+								<Badge color={tone} testId="ai-message-output-badge">
+									Output
+								</Badge>
+							)}
+						</div>
+					)}
+					{parts}
+				</>
+			)}
+			{finishReason && (
+				<PartChip
+					label="Finish Reason"
+					value={finishReason}
+					tone={tone}
+					testId="ai-message-finish-reason"
+				/>
+			)}
+		</div>
+	);
+}
+
+AIThreadMessage.defaultProps = {
+	isOutput: false,
+	isToolLinkEnabled: undefined,
+	onToolLinkClick: undefined,
+};
+
+export default AIThreadMessage;

frontend/src/pages/TraceDetailsV3/AIThreadMessage/CollapsibleBlock.tsx

@@ -0,0 +1,50 @@
+import { MouseEvent, ReactNode, useState } from 'react';
+import { ChevronDown, ChevronUp } from '@signozhq/icons';
+import cx from 'classnames';
+
+import styles from './AIThreadMessage.module.scss';
+
+interface CollapsibleBlockProps {
+	label: ReactNode;
+	// Boxed: full-width bordered row with the chevron on the right.
+	isBoxed?: boolean;
+	testId?: string;
+	children: ReactNode;
+}
+
+function CollapsibleBlock({
+	label,
+	isBoxed = false,
+	testId,
+	children,
+}: CollapsibleBlockProps): JSX.Element {
+	const [isOpen, setIsOpen] = useState(false);
+
+	const handleToggle = (event: MouseEvent): void => {
+		event.stopPropagation();
+		setIsOpen((prev) => !prev);
+	};
+
+	return (
+		<div className={cx(styles.collapsible, isBoxed && styles.boxed)}>
+			<button
+				type="button"
+				className={styles.collapsibleToggle}
+				onClick={handleToggle}
+				aria-expanded={isOpen}
+				data-testid={testId}
+			>
+				<span className={styles.collapsibleLabel}>{label}</span>
+				{isOpen ? <ChevronUp size={12} /> : <ChevronDown size={12} />}
+			</button>
+			{isOpen && <div className={styles.collapsibleBody}>{children}</div>}
+		</div>
+	);
+}
+
+CollapsibleBlock.defaultProps = {
+	isBoxed: false,
+	testId: undefined,
+};
+
+export default CollapsibleBlock;

frontend/src/pages/TraceDetailsV3/AIThreadMessage/ExpandableText.tsx

@@ -0,0 +1,56 @@
+import { MouseEvent, useState } from 'react';
+import cx from 'classnames';
+import { MarkdownRenderer } from 'components/MarkdownRenderer/MarkdownRenderer';
+
+import { MAX_TEXT_LENGTH } from './utils';
+
+import styles from './AIThreadMessage.module.scss';
+
+interface ExpandableTextProps {
+	text: string;
+	isMarkdown?: boolean;
+}
+
+function ExpandableText({
+	text,
+	isMarkdown = false,
+}: ExpandableTextProps): JSX.Element {
+	const [isExpanded, setIsExpanded] = useState(false);
+	const isTruncated = !isExpanded && text.length > MAX_TEXT_LENGTH;
+	const visibleText = isTruncated ? `${text.slice(0, MAX_TEXT_LENGTH)}…` : text;
+
+	const handleToggle = (event: MouseEvent): void => {
+		event.stopPropagation();
+		setIsExpanded((prev) => !prev);
+	};
+
+	return (
+		<>
+			{isMarkdown ? (
+				<MarkdownRenderer
+					className={styles.text}
+					markdownContent={visibleText}
+					variables={{}}
+				/>
+			) : (
+				<div className={cx(styles.text, styles.plainText)}>{visibleText}</div>
+			)}
+			{text.length > MAX_TEXT_LENGTH && (
+				<button
+					type="button"
+					className={styles.showMore}
+					onClick={handleToggle}
+					data-testid="ai-message-show-more"
+				>
+					{isExpanded ? 'Show less' : 'Show more'}
+				</button>
+			)}
+		</>
+	);
+}
+
+ExpandableText.defaultProps = {
+	isMarkdown: false,
+};
+
+export default ExpandableText;

frontend/src/pages/TraceDetailsV3/AIThreadMessage/JsonBlock.tsx

@@ -0,0 +1,26 @@
+import { PrettyView } from 'periscope/components/PrettyView';
+
+import styles from './AIThreadMessage.module.scss';
+
+interface JsonBlockProps {
+	data: object;
+}
+
+// Expanding tree nodes must not count as a click on the message.
+function JsonBlock({ data }: JsonBlockProps): JSX.Element {
+	return (
+		// eslint-disable-next-line jsx-a11y/click-events-have-key-events, jsx-a11y/no-static-element-interactions
+		<div
+			className={styles.json}
+			onClick={(event): void => event.stopPropagation()}
+		>
+			<PrettyView
+				data={data as Record<string, unknown>}
+				searchable={false}
+				drawerKey="ai-thread-message"
+			/>
+		</div>
+	);
+}
+
+export default JsonBlock;

frontend/src/pages/TraceDetailsV3/AIThreadMessage/MessagePart.tsx

@@ -0,0 +1,64 @@
+import { MessagePart as MessagePartType } from '../TraceDetailsThread/types';
+import MediaPart from './parts/MediaPart';
+import ThinkingPart from './parts/ThinkingPart';
+import ToolCallPart from './parts/ToolCallPart';
+import ToolResultPart from './parts/ToolResultPart';
+import TextContent from './TextContent';
+
+interface MessagePartProps {
+	part: MessagePartType;
+	isToolLinkEnabled?: (toolCallId: string) => boolean;
+	onToolLinkClick?: (toolCallId: string) => void;
+}
+
+function MessagePart({
+	part,
+	isToolLinkEnabled,
+	onToolLinkClick,
+}: MessagePartProps): JSX.Element | null {
+	switch (part.type) {
+		case 'text':
+			return <TextContent text={part.content} isMarkdown />;
+		case 'thinking':
+			return <ThinkingPart content={part.content} />;
+		case 'tool_call':
+			return (
+				<ToolCallPart
+					id={part.id}
+					name={part.name}
+					args={part.arguments}
+					server={part.server}
+				/>
+			);
+		case 'tool_result':
+			return (
+				<ToolResultPart
+					toolCallId={part.toolCallId}
+					name={part.name}
+					content={part.content}
+					isError={part.isError}
+					isLinkEnabled={!!isToolLinkEnabled?.(part.toolCallId)}
+					onLinkClick={onToolLinkClick}
+				/>
+			);
+		case 'media':
+			return (
+				<MediaPart
+					modality={part.modality}
+					mimeType={part.mimeType}
+					name={part.name}
+				/>
+			);
+		case 'generic':
+			return <TextContent text={part.content} />;
+		default:
+			return null;
+	}
+}
+
+MessagePart.defaultProps = {
+	isToolLinkEnabled: undefined,
+	onToolLinkClick: undefined,
+};
+
+export default MessagePart;

frontend/src/pages/TraceDetailsV3/AIThreadMessage/PartChip.tsx

@@ -0,0 +1,44 @@
+import { ReactNode } from 'react';
+
+import { MessageTone } from './utils';
+
+import styles from './AIThreadMessage.module.scss';
+
+interface PartChipProps {
+	label: string;
+	value?: ReactNode;
+	tone?: MessageTone;
+	testId?: string;
+	children?: ReactNode;
+}
+
+function PartChip({
+	label,
+	value,
+	tone = 'success',
+	testId,
+	children,
+}: PartChipProps): JSX.Element {
+	return (
+		<span className={styles.chip} data-testid={testId}>
+			<span className={styles.dot} data-tone={tone} />
+			<span className={styles.chipLabel}>{label}</span>
+			{value !== undefined && (
+				<>
+					<span className={styles.chipSeparator}>—</span>
+					<span className={styles.chipValue}>{value}</span>
+				</>
+			)}
+			{children}
+		</span>
+	);
+}
+
+PartChip.defaultProps = {
+	value: undefined,
+	tone: 'success',
+	testId: undefined,
+	children: undefined,
+};
+
+export default PartChip;

frontend/src/pages/TraceDetailsV3/AIThreadMessage/TextContent.tsx

@@ -0,0 +1,35 @@
+import { useMemo } from 'react';
+
+import ExpandableText from './ExpandableText';
+import JsonBlock from './JsonBlock';
+import { parseJsonObject } from './utils';
+
+import styles from './AIThreadMessage.module.scss';
+
+interface TextContentProps {
+	text: string;
+	isMarkdown?: boolean;
+}
+
+/** Renders JSON text as a tree, anything else as (markdown) text. */
+function TextContent({
+	text,
+	isMarkdown = false,
+}: TextContentProps): JSX.Element {
+	const json = useMemo(() => parseJsonObject(text), [text]);
+
+	if (json) {
+		return <JsonBlock data={json} />;
+	}
+	return (
+		<div className={styles.textBox}>
+			<ExpandableText text={text} isMarkdown={isMarkdown} />
+		</div>
+	);
+}
+
+TextContent.defaultProps = {
+	isMarkdown: false,
+};
+
+export default TextContent;

frontend/src/pages/TraceDetailsV3/AIThreadMessage/parts/MediaPart.tsx

@@ -0,0 +1,28 @@
+import { Image } from '@signozhq/icons';
+
+import styles from '../AIThreadMessage.module.scss';
+
+interface MediaPartProps {
+	modality?: string;
+	mimeType?: string;
+	name?: string;
+}
+
+function MediaPart({ modality, mimeType, name }: MediaPartProps): JSX.Element {
+	return (
+		<span className={styles.mediaChip} data-testid="ai-media-part">
+			<Image size={12} />
+			<span className="translate-safe">
+				{name || mimeType || modality || 'Media'}
+			</span>
+		</span>
+	);
+}
+
+MediaPart.defaultProps = {
+	modality: undefined,
+	mimeType: undefined,
+	name: undefined,
+};
+
+export default MediaPart;

frontend/src/pages/TraceDetailsV3/AIThreadMessage/parts/ThinkingPart.tsx

@@ -0,0 +1,30 @@
+import CollapsibleBlock from '../CollapsibleBlock';
+import ExpandableText from '../ExpandableText';
+
+import styles from '../AIThreadMessage.module.scss';
+
+interface ThinkingPartProps {
+	content?: string;
+}
+
+function ThinkingPart({ content }: ThinkingPartProps): JSX.Element {
+	return (
+		<CollapsibleBlock
+			label="Thinking"
+			isBoxed
+			testId="ai-message-thinking-toggle"
+		>
+			{content ? (
+				<ExpandableText text={content} isMarkdown />
+			) : (
+				<span className={styles.empty}>Reasoning content not captured</span>
+			)}
+		</CollapsibleBlock>
+	);
+}
+
+ThinkingPart.defaultProps = {
+	content: undefined,
+};
+
+export default ThinkingPart;

frontend/src/pages/TraceDetailsV3/AIThreadMessage/parts/ToolCallPart.tsx

@@ -0,0 +1,69 @@
+import { useMemo } from 'react';
+import { Badge } from '@signozhq/ui/badge';
+
+import JsonBlock from '../JsonBlock';
+import PartChip from '../PartChip';
+import TextContent from '../TextContent';
+import { parseJsonObject, TOOL_CALL_ID_ATTR } from '../utils';
+
+import styles from '../AIThreadMessage.module.scss';
+
+interface ToolCallPartProps {
+	id: string;
+	name: string;
+	args: unknown;
+	server?: boolean;
+}
+
+function ToolCallPart({
+	id,
+	name,
+	args,
+	server,
+}: ToolCallPartProps): JSX.Element {
+	// Streamed calls can carry truncated, unparseable argument strings.
+	const json = useMemo(() => {
+		if (typeof args === 'string') {
+			return parseJsonObject(args);
+		}
+		return typeof args === 'object' && args !== null ? args : undefined;
+	}, [args]);
+
+	const toolCallAttr = { [TOOL_CALL_ID_ATTR]: id };
+
+	return (
+		<div className={styles.toolCall} {...toolCallAttr} data-testid="ai-tool-call">
+			<PartChip
+				label="tool_call"
+				value={
+					<>
+						<span className={styles.chipKey}>name :</span>
+						<span className={styles.toolName}>{name}</span>
+					</>
+				}
+			>
+				{server && (
+					<Badge color="secondary" variant="outline">
+						server
+					</Badge>
+				)}
+			</PartChip>
+			{json ? (
+				<JsonBlock data={json} />
+			) : (
+				args !== undefined &&
+				args !== null && (
+					<TextContent
+						text={typeof args === 'string' ? args : JSON.stringify(args)}
+					/>
+				)
+			)}
+		</div>
+	);
+}
+
+ToolCallPart.defaultProps = {
+	server: false,
+};
+
+export default ToolCallPart;

frontend/src/pages/TraceDetailsV3/AIThreadMessage/parts/ToolResultPart.tsx

@@ -0,0 +1,69 @@
+import { MouseEvent, useMemo } from 'react';
+import { CornerUpRight } from '@signozhq/icons';
+
+import PartChip from '../PartChip';
+import TextContent from '../TextContent';
+import { MAX_INLINE_RESULT_LENGTH, parseJsonObject } from '../utils';
+
+import styles from '../AIThreadMessage.module.scss';
+
+interface ToolResultPartProps {
+	toolCallId: string;
+	name?: string;
+	content: string;
+	isError?: boolean;
+	isLinkEnabled: boolean;
+	onLinkClick?: (toolCallId: string) => void;
+}
+
+function ToolResultPart({
+	toolCallId,
+	name,
+	content,
+	isError,
+	isLinkEnabled,
+	onLinkClick,
+}: ToolResultPartProps): JSX.Element {
+	// Short plain results fit in the chip; JSON or long ones render below it.
+	const isInline = useMemo(
+		() => content.length <= MAX_INLINE_RESULT_LENGTH && !parseJsonObject(content),
+		[content],
+	);
+
+	const handleLinkClick = (event: MouseEvent): void => {
+		event.stopPropagation();
+		onLinkClick?.(toolCallId);
+	};
+
+	return (
+		<div className={styles.toolResult} data-testid="ai-tool-result">
+			<PartChip
+				label="tool_result"
+				value={isInline ? content || '…' : name || toolCallId}
+				tone={isError ? 'error' : 'success'}
+			>
+				<button
+					type="button"
+					className={styles.toolLink}
+					disabled={!isLinkEnabled}
+					onClick={handleLinkClick}
+					title={
+						isLinkEnabled ? 'Go to tool call' : 'Matching tool call is not loaded'
+					}
+					data-testid="ai-tool-result-link"
+				>
+					<CornerUpRight size={12} />
+				</button>
+			</PartChip>
+			{!isInline && <TextContent text={content} />}
+		</div>
+	);
+}
+
+ToolResultPart.defaultProps = {
+	name: undefined,
+	isError: false,
+	onLinkClick: undefined,
+};
+
+export default ToolResultPart;

frontend/src/pages/TraceDetailsV3/AIThreadMessage/useToolCallLinks.ts

@@ -0,0 +1,43 @@
+import { RefObject, useCallback } from 'react';
+
+import { TOOL_CALL_ID_ATTR } from './utils';
+
+import styles from './AIThreadMessage.module.scss';
+
+const HIGHLIGHT_MS = 1500;
+
+interface ToolCallLinks {
+	isToolLinkEnabled: (toolCallId: string) => boolean;
+	onToolLinkClick: (toolCallId: string) => void;
+}
+
+/** Links tool results to their calls in `rootRef`; enabled only for ids in `toolCallIds`. */
+export function useToolCallLinks(
+	rootRef: RefObject<HTMLElement>,
+	toolCallIds: Set<string>,
+): ToolCallLinks {
+	const isToolLinkEnabled = useCallback(
+		(toolCallId: string): boolean => toolCallIds.has(toolCallId),
+		[toolCallIds],
+	);
+
+	const onToolLinkClick = useCallback(
+		(toolCallId: string): void => {
+			const target = rootRef.current?.querySelector<HTMLElement>(
+				`[${TOOL_CALL_ID_ATTR}="${CSS.escape(toolCallId)}"]`,
+			);
+			if (!target) {
+				return;
+			}
+			target.scrollIntoView({ behavior: 'smooth', block: 'center' });
+			target.classList.add(styles.isHighlighted);
+			window.setTimeout(
+				() => target.classList.remove(styles.isHighlighted),
+				HIGHLIGHT_MS,
+			);
+		},
+		[rootRef],
+	);
+
+	return { isToolLinkEnabled, onToolLinkClick };
+}

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

@@ -0,0 +1,53 @@
+import { ThreadMessage } from '../TraceDetailsThread/types';
+
+export const MAX_TEXT_LENGTH = 1000;
+
+export const MAX_INLINE_RESULT_LENGTH = 80;
+
+export const TOOL_CALL_ID_ATTR = 'data-tool-call-id';
+
+const ROLE_LABELS: Record<string, string> = {
+	system: 'System',
+	user: 'User',
+	assistant: 'Assistant',
+	tool: 'Tool',
+};
+
+export type MessageTone = 'success' | 'warning' | 'error';
+
+const FINISH_REASON_TONES: Record<string, MessageTone> = {
+	length: 'warning',
+	content_filter: 'warning',
+	error: 'error',
+};
+
+/** Undefined for missing or unknown roles, which render headerless. */
+export function getRoleLabel(role?: string): string | undefined {
+	return role ? ROLE_LABELS[role] : undefined;
+}
+
+export function getFinishReasonTone(reason?: string): MessageTone {
+	return (reason && FINISH_REASON_TONES[reason]) || 'success';
+}
+
+/** Parses objects and arrays only; scalars and invalid JSON return undefined. */
+export function parseJsonObject(text: string): object | undefined {
+	const trimmed = text.trim();
+	if (!trimmed.startsWith('{') && !trimmed.startsWith('[')) {
+		return undefined;
+	}
+	try {
+		const parsed: unknown = JSON.parse(trimmed);
+		return typeof parsed === 'object' && parsed !== null ? parsed : undefined;
+	} catch {
+		return undefined;
+	}
+}
+
+export function collectToolCallIds(messages: ThreadMessage[]): string[] {
+	return messages.flatMap((message) =>
+		message.content.flatMap((part) =>
+			part.type === 'tool_call' ? [part.id] : [],
+		),
+	);
+}

frontend/src/pages/TraceDetailsV3/EntityMetadata/EntityMetadataItem.tsx

@@ -5,18 +5,23 @@ import { Typography } from '@signozhq/ui/typography';
 import styles from './EntityMetadataItem.module.scss';
 
 interface EntityMetadataItemProps {
-	tooltip: string;
+	tooltip: ReactNode;
+	tooltipClassName?: string;
 	icon?: ReactNode;
 	children: ReactNode;
 }
 
 function EntityMetadataItem({
 	tooltip,
+	tooltipClassName,
 	icon,
 	children,
 }: EntityMetadataItemProps): JSX.Element {
 	return (
-		<TooltipSimple title={tooltip}>
+		<TooltipSimple
+			title={tooltip}
+			tooltipContentProps={{ className: tooltipClassName }}
+		>
 			<span className={styles.item}>
 				{icon}
 				<Typography.Text as="span">{children}</Typography.Text>
@@ -27,6 +32,7 @@ function EntityMetadataItem({
 
 EntityMetadataItem.defaultProps = {
 	icon: null,
+	tooltipClassName: undefined,
 };
 
 export default EntityMetadataItem;

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

@@ -8,3 +8,16 @@
 	// Keep Typography.Text at the row's size (it reads this var, not inherited font-size).
 	--typography-font-size: var(--periscope-font-size-base);
 }
+
+.tokenTooltip {
+	composes: tooltipBody from '../shared.module.scss';
+	min-width: 160px;
+}
+
+.tokenTooltipTitle {
+	padding-bottom: var(--spacing-4);
+}
+
+.tokenTooltipContent {
+	composes: tooltipContent from '../shared.module.scss';
+}

frontend/src/pages/TraceDetailsV3/EntityMetadata/EntityMetadataRow.tsx

@@ -1,10 +1,13 @@
-import { CalendarClock, Server, Timer } from '@signozhq/icons';
+import { CalendarClock, Coins, Landmark, Server, Timer } from '@signozhq/icons';
 import { Badge } from '@signozhq/ui/badge';
 import cx from 'classnames';
 import { getYAxisFormattedValue } from 'components/Graph/yAxisConfig';
 import HttpStatusBadge from 'components/HttpStatusBadge/HttpStatusBadge';
 
+import { formatCost, formatTokens } from '../utils/genAi';
+import { TokenUsage } from '../SpanHoverCard/aiUsage';
 import EntityMetadataItem from './EntityMetadataItem';
+import TokenUsageTooltip from './TokenUsageTooltip';
 
 import styles from './EntityMetadataRow.module.scss';
 
@@ -16,6 +19,8 @@ interface EntityMetadataRowProps {
 	execTimePercent?: number;
 	timestamp?: string;
 	statusCode?: string | number;
+	tokens?: TokenUsage;
+	cost?: number;
 }
 
 const ICON_SIZE = 14;
@@ -32,6 +37,8 @@ function EntityMetadataRow({
 	execTimePercent,
 	timestamp,
 	statusCode,
+	tokens,
+	cost,
 }: EntityMetadataRowProps): JSX.Element {
 	const entityLabel = entity === 'trace' ? 'Trace' : 'Span';
 	const durationTooltip =
@@ -91,6 +98,25 @@ function EntityMetadataRow({
 					<HttpStatusBadge statusCode={statusCode} />
 				</EntityMetadataItem>
 			)}
+
+			{tokens && (tokens.input > 0 || tokens.output > 0) && (
+				<EntityMetadataItem
+					tooltip={<TokenUsageTooltip tokens={tokens} />}
+					tooltipClassName={styles.tokenTooltipContent}
+					icon={<Coins size={ICON_SIZE} />}
+				>
+					Tokens: {formatTokens(tokens.input)} → {formatTokens(tokens.output)}
+				</EntityMetadataItem>
+			)}
+
+			{cost !== undefined && (
+				<EntityMetadataItem
+					tooltip="Total cost"
+					icon={<Landmark size={ICON_SIZE} />}
+				>
+					Cost — {formatCost(cost)}
+				</EntityMetadataItem>
+			)}
 		</div>
 	);
 }
@@ -102,6 +128,8 @@ EntityMetadataRow.defaultProps = {
 	execTimePercent: undefined,
 	timestamp: undefined,
 	statusCode: undefined,
+	tokens: undefined,
+	cost: undefined,
 };
 
 export default EntityMetadataRow;

frontend/src/pages/TraceDetailsV3/EntityMetadata/TokenUsageTooltip.tsx

@@ -0,0 +1,34 @@
+import { Typography } from '@signozhq/ui/typography';
+
+import TokenBreakdown from '../TraceTooltip/TokenBreakdown';
+import { TokenUsage } from '../SpanHoverCard/aiUsage';
+
+import styles from './EntityMetadataRow.module.scss';
+
+interface TokenUsageTooltipProps {
+	tokens: TokenUsage;
+}
+
+function TokenUsageTooltip({ tokens }: TokenUsageTooltipProps): JSX.Element {
+	const { input, output, cacheRead, cacheWrite } = tokens;
+
+	return (
+		<div className={styles.tokenTooltip}>
+			<Typography.Text
+				size="small"
+				weight="medium"
+				className={styles.tokenTooltipTitle}
+			>
+				Usage Breakdown
+			</Typography.Text>
+			<TokenBreakdown
+				input={input}
+				output={output}
+				cacheRead={cacheRead}
+				cacheWrite={cacheWrite}
+			/>
+		</div>
+	);
+}
+
+export default TokenUsageTooltip;

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

@@ -0,0 +1,25 @@
+.root {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-4);
+	padding: var(--spacing-4) 0;
+}
+
+.header {
+	display: flex;
+	align-items: center;
+	justify-content: space-between;
+	font-size: var(--font-size-xs);
+	font-weight: var(--font-weight-medium);
+	color: var(--l2-foreground);
+	text-transform: uppercase;
+	letter-spacing: var(--letter-spacing-wide);
+}
+
+.scroll {
+	max-height: 480px;
+	overflow-y: auto;
+	padding: var(--spacing-4);
+	border: 1px solid var(--l2-border);
+	border-radius: var(--radius-2);
+}

frontend/src/pages/TraceDetailsV3/SpanDetailsPanel/SpanAIMessages/SpanAIMessages.tsx

@@ -0,0 +1,62 @@
+import { useMemo, useRef, useState } from 'react';
+
+import { useToolCallLinks } from '../../AIThreadMessage/useToolCallLinks';
+import SpanMessages from '../../SpanMessages/SpanMessages';
+import {
+	getSpanMessages,
+	hasAnyMessages,
+	hasFormattedMessages,
+} from '../../SpanMessages/utils';
+import { ThreadSpan, ThreadView } from '../../TraceDetailsThread/types';
+import ThreadViewToggle from '../../TraceDetailsThread/ThreadViewToggle';
+import { buildToolCallIndex } from '../../TraceDetailsThread/utils';
+
+import styles from './SpanAIMessages.module.scss';
+
+interface SpanAIMessagesProps {
+	span: ThreadSpan;
+}
+
+/** Waterfall spans only carry raw attributes, so they get the JSON view alone. */
+function SpanAIMessages({ span }: SpanAIMessagesProps): JSX.Element | null {
+	const data = useMemo(() => getSpanMessages(span), [span]);
+	const canFormat = hasFormattedMessages(data);
+	const [view, setView] = useState(ThreadView.Formatted);
+	const effectiveView = canFormat ? view : ThreadView.Json;
+
+	const scrollRef = useRef<HTMLDivElement>(null);
+	const toolCallIds = useMemo(() => buildToolCallIndex([span]), [span]);
+	const { isToolLinkEnabled, onToolLinkClick } = useToolCallLinks(
+		scrollRef,
+		toolCallIds,
+	);
+
+	if (!hasAnyMessages(data)) {
+		return null;
+	}
+
+	return (
+		<div className={styles.root} data-testid="span-ai-messages">
+			<div className={styles.header}>
+				Messages
+				{canFormat && (
+					<ThreadViewToggle
+						value={effectiveView}
+						onChange={setView}
+						testId="span-ai-messages-view-toggle"
+					/>
+				)}
+			</div>
+			<div className={styles.scroll} ref={scrollRef}>
+				<SpanMessages
+					span={span}
+					view={effectiveView}
+					isToolLinkEnabled={isToolLinkEnabled}
+					onToolLinkClick={onToolLinkClick}
+				/>
+			</div>
+		</div>
+	);
+}
+
+export default SpanAIMessages;

frontend/src/pages/TraceDetailsV3/SpanDetailsPanel/SpanDetailsPanel.tsx

@@ -52,6 +52,7 @@ import Events from './Events/Events';
 import OpenInLogsExplorer from './SpanLogs/OpenInLogsExplorer';
 import SpanLogs from './SpanLogs/SpanLogs';
 import { useSpanContextLogs } from './SpanLogs/useSpanContextLogs';
+import SpanAIMessages from './SpanAIMessages/SpanAIMessages';
 import SpanSummary from './SpanSummary';
 
 import styles from './SpanDetailsPanel.module.scss';
@@ -320,6 +321,7 @@ function SpanDetailsContent({
 						<div className={styles.tabsScroll}>
 							<TabsContent value="overview">
 								{isWide && summary}
+								<SpanAIMessages span={selectedSpan} />
 								<DataViewer
 									data={spanDisplayData}
 									drawerKey="trace-details"

frontend/src/pages/TraceDetailsV3/SpanDetailsPanel/SpanSummary.tsx

@@ -1,9 +1,11 @@
+import { useMemo } from 'react';
 import { Link2 } from '@signozhq/icons';
 import dayjs from 'dayjs';
 import KeyValueLabel from 'periscope/components/KeyValueLabel';
 import { SpanV3 } from 'types/api/trace/getTraceV3';
 
 import EntityMetadataRow from '../EntityMetadata/EntityMetadataRow';
+import { getSpanAiDetails, getSpanTokenUsage } from '../SpanHoverCard/aiUsage';
 import { HIGHLIGHTED_OPTIONS } from './config';
 import {
 	LinkedSpansPanel,
@@ -31,6 +33,11 @@ function SpanSummary({
 }: SpanSummaryProps): JSX.Element {
 	const percentile = useSpanPercentile(selectedSpan);
 	const linkedSpans = useLinkedSpans((selectedSpan as any).references);
+	const tokens = useMemo(() => getSpanTokenUsage(selectedSpan), [selectedSpan]);
+	const cost = useMemo(
+		() => getSpanAiDetails(selectedSpan)?.usage?.cost,
+		[selectedSpan],
+	);
 
 	return (
 		<>
@@ -63,6 +70,8 @@ function SpanSummary({
 							: undefined
 					}
 					timestamp={dayjs(selectedSpan.timestamp).format('HH:mm:ss — MMM D, YYYY')}
+					tokens={tokens}
+					cost={cost}
 				/>
 
 				<div className={styles.spanInfoItem}>

frontend/src/pages/TraceDetailsV3/SpanHintBadge/SpanHintBadge.tsx

@@ -0,0 +1,37 @@
+import { CSSProperties } from 'react';
+import { Badge } from '@signozhq/ui/badge';
+import HttpStatusBadge from 'components/HttpStatusBadge/HttpStatusBadge';
+import { SpanV3 } from 'types/api/trace/getTraceV3';
+
+import { getAiSpanKind } from '../utils/genAi';
+import { AI_SPAN_BADGES } from './constants';
+
+interface SpanHintBadgeProps {
+	span: SpanV3;
+}
+
+function SpanHintBadge({ span }: SpanHintBadgeProps): JSX.Element | null {
+	const aiSpanKind = getAiSpanKind(span);
+
+	if (aiSpanKind) {
+		const { label, color } = AI_SPAN_BADGES[aiSpanKind];
+		return (
+			<Badge
+				variant="outline"
+				// The outline variant derives text, fill and border from this color.
+				style={{ '--badge-background': color } as CSSProperties}
+				data-testid={`span-hint-badge-${aiSpanKind}`}
+			>
+				{label}
+			</Badge>
+		);
+	}
+
+	if (!span.response_status_code) {
+		return null;
+	}
+
+	return <HttpStatusBadge statusCode={span.response_status_code} />;
+}
+
+export default SpanHintBadge;

frontend/src/pages/TraceDetailsV3/SpanHintBadge/__tests__/SpanHintBadge.test.tsx

@@ -0,0 +1,39 @@
+import { render, screen } from '@testing-library/react';
+import { SpanV3 } from 'types/api/trace/getTraceV3';
+
+import SpanHintBadge from '../SpanHintBadge';
+
+const spanWith = (
+	attributes: Record<string, string | number>,
+	responseStatusCode = '',
+): SpanV3 =>
+	({
+		attributes,
+		resource: {},
+		response_status_code: responseStatusCode,
+	}) as unknown as SpanV3;
+
+describe('SpanHintBadge', () => {
+	it.each([
+		[{ 'gen_ai.request.model': 'gpt-4o' }, 'LLM'],
+		[{ 'gen_ai.tool.name': 'search' }, 'TOOL'],
+		[{ 'gen_ai.agent.name': 'planner' }, 'AGENT'],
+	])('shows only the AI badge for %p', (attributes, label) => {
+		render(<SpanHintBadge span={spanWith(attributes, '200')} />);
+
+		expect(screen.getByText(label)).toBeInTheDocument();
+		expect(screen.queryByText('200')).not.toBeInTheDocument();
+	});
+
+	it('falls back to the HTTP status code for non-AI spans', () => {
+		render(<SpanHintBadge span={spanWith({}, '503')} />);
+
+		expect(screen.getByText('503')).toBeInTheDocument();
+	});
+
+	it('renders nothing for a non-AI span without a status code', () => {
+		const { container } = render(<SpanHintBadge span={spanWith({})} />);
+
+		expect(container).toBeEmptyDOMElement();
+	});
+});

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

@@ -0,0 +1,10 @@
+import { AiSpanKind } from '../utils/genAi';
+
+export const AI_SPAN_BADGES: Record<
+	AiSpanKind,
+	{ label: string; color: string }
+> = {
+	[AiSpanKind.Llm]: { label: 'LLM', color: 'rgba(155, 255, 0, 1)' },
+	[AiSpanKind.Tool]: { label: 'TOOL', color: 'rgba(255, 209, 0, 1)' },
+	[AiSpanKind.Agent]: { label: 'AGENT', color: 'rgba(255, 10, 138, 1)' },
+};

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

@@ -9,40 +9,24 @@
 }
 
 .popover {
+	composes: tooltipContent from '../shared.module.scss';
 	// Hover card may be rendered while the SpanDetailsPanel is docked as
 	// a FloatingPanel (z-index 999); bump above the default tooltip z-index.
 	--tooltip-z-index: 1000;
-	background-color: var(--l1-background);
-	padding: 8px 12px;
-	border-radius: 4px;
-	box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
-	border: 1px solid var(--l2-border);
-	color: var(--l1-foreground);
 }
 
 .content {
-	font-size: 12px;
-	color: var(--l1-foreground);
+	composes: tooltipBody from '../shared.module.scss';
+	width: 223px;
 }
 
-.name {
-	font-weight: 600;
-	margin-bottom: 4px;
+.title {
+	composes: tooltipTitle from '../shared.module.scss';
 }
 
-.row {
-	line-height: 1.5;
-	color: var(--l2-foreground);
-}
-
-.preview {
-	// container for additional preview rows
-}
-
-.previewKey {
-	color: var(--l2-foreground);
-}
-
-.previewValue {
-	color: var(--l1-foreground);
+.header {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-2);
+	padding-bottom: var(--spacing-4);
 }

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

@@ -4,6 +4,7 @@ import {
 	TooltipProvider,
 	TooltipTrigger,
 } from '@signozhq/ui/tooltip';
+import { Typography } from '@signozhq/ui/typography';
 import { convertTimeToRelevantUnit } from 'utils/traceUtils';
 import { useIsDarkMode } from 'hooks/useDarkMode';
 import { useTraceStore } from 'pages/TraceDetailsV3/stores/traceStore';
@@ -12,6 +13,11 @@ import { useMemo } from 'react';
 import { SpanV3 } from 'types/api/trace/getTraceV3';
 import { toFixed } from 'utils/toFixed';
 
+import { getSpanAiDetails, SpanAiDetails } from './aiUsage';
+import SpanUsageBreakdown from './SpanUsageBreakdown';
+import TooltipRow from '../TraceTooltip/TooltipRow';
+import TooltipSection from '../TraceTooltip/TooltipSection';
+
 import styles from './SpanHoverCard.module.scss';
 
 /**
@@ -38,6 +44,7 @@ export interface SpanTooltipContentProps {
 	relativeStartMs: number;
 	durationMs: number;
 	previewRows?: SpanPreviewRow[];
+	ai?: SpanAiDetails;
 }
 
 export function SpanTooltipContent({
@@ -47,33 +54,46 @@ export function SpanTooltipContent({
 	relativeStartMs,
 	durationMs,
 	previewRows,
+	ai,
 }: SpanTooltipContentProps): JSX.Element {
 	const { time: formattedDuration, timeUnitName } =
 		convertTimeToRelevantUnit(durationMs);
 
 	return (
 		<div className={styles.content}>
-			<div className={styles.name} style={{ color }}>
-				{spanName}
-			</div>
-			<div className={styles.row}>status: {hasError ? 'error' : 'ok'}</div>
-			<div className={styles.row}>start: {toFixed(relativeStartMs, 2)} ms</div>
-			<div className={styles.row}>
-				duration: {toFixed(formattedDuration, 2)} {timeUnitName}
+			<div className={styles.header}>
+				<Typography.Text className={styles.title} style={{ color }}>
+					{spanName}
+				</Typography.Text>
+				{ai?.usage && (
+					<Typography.Text size="small" weight="medium">
+						Usage Breakdown
+					</Typography.Text>
+				)}
 			</div>
+			{ai?.usage && <SpanUsageBreakdown usage={ai.usage} />}
+			<TooltipSection>
+				{ai?.model && <TooltipRow label="model" value={ai.model} />}
+				{ai?.toolName && <TooltipRow label="tool" value={ai.toolName} />}
+				{ai?.agentName && <TooltipRow label="agent" value={ai.agentName} />}
+				<TooltipRow label="status" value={hasError ? 'error' : 'ok'} />
+				<TooltipRow label="start" value={`${toFixed(relativeStartMs, 2)} ms`} />
+				<TooltipRow
+					label="duration"
+					value={`${toFixed(formattedDuration, 2)} ${timeUnitName}`}
+				/>
+			</TooltipSection>
 			{previewRows && previewRows.length > 0 && (
-				<div className={styles.preview}>
+				<TooltipSection>
 					{previewRows.map((row) => (
-						<div
+						<TooltipRow
 							key={row.key}
-							className={styles.row}
-							data-testid={`span-hover-card-preview-${row.key}`}
-						>
-							<span className={styles.previewKey}>{row.key}:</span>{' '}
-							<span className={styles.previewValue}>{row.value}</span>
-						</div>
+							label={row.key}
+							value={row.value}
+							testId={`span-hover-card-preview-${row.key}`}
+						/>
 					))}
-				</div>
+				</TooltipSection>
 			)}
 		</div>
 	);
@@ -137,6 +157,7 @@ export function SpanHoverCard({
 				relativeStartMs: span.timestamp - traceStartTime,
 				durationMs: span.duration_nano / 1e6,
 				previewRows,
+				ai: getSpanAiDetails(span),
 			},
 		};
 	}, [

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

@@ -0,0 +1,37 @@
+import { formatCost } from '../utils/genAi';
+import { SpanAiUsage } from './aiUsage';
+import TokenBreakdown from '../TraceTooltip/TokenBreakdown';
+import TooltipRow from '../TraceTooltip/TooltipRow';
+import TooltipSection from '../TraceTooltip/TooltipSection';
+
+interface SpanUsageBreakdownProps {
+	usage: SpanAiUsage;
+}
+
+function SpanUsageBreakdown({ usage }: SpanUsageBreakdownProps): JSX.Element {
+	const {
+		inputTokens,
+		outputTokens,
+		cacheReadTokens,
+		cacheCreationTokens,
+		cost,
+	} = usage;
+
+	return (
+		<>
+			<TokenBreakdown
+				input={inputTokens}
+				output={outputTokens}
+				cacheRead={cacheReadTokens}
+				cacheWrite={cacheCreationTokens}
+			/>
+			{cost !== undefined && (
+				<TooltipSection>
+					<TooltipRow label="cost" value={formatCost(cost)} />
+				</TooltipSection>
+			)}
+		</>
+	);
+}
+
+export default SpanUsageBreakdown;

frontend/src/pages/TraceDetailsV3/SpanHoverCard/__tests__/SpanTooltipContent.test.tsx

@@ -0,0 +1,143 @@
+import { render, screen } from '@testing-library/react';
+import { SpanV3 } from 'types/api/trace/getTraceV3';
+
+import { getSpanAiDetails } from '../aiUsage';
+import { SpanTooltipContent } from '../SpanHoverCard';
+
+const baseProps = {
+	spanName: 'chat gpt-4o',
+	color: '#fff',
+	hasError: false,
+	relativeStartMs: 268,
+	durationMs: 1110,
+};
+
+const spanWith = (attributes: Record<string, string | number>): SpanV3 =>
+	({ attributes, resource: {} }) as unknown as SpanV3;
+
+describe('getSpanAiDetails', () => {
+	it('returns undefined for a span without gen_ai attributes', () => {
+		expect(getSpanAiDetails(spanWith({ 'http.method': 'GET' }))).toBeUndefined();
+	});
+
+	it('reads model, tool, agent, token usage and cost', () => {
+		expect(
+			getSpanAiDetails(
+				spanWith({
+					'gen_ai.request.model': 'gpt-4o',
+					'gen_ai.tool.name': 'search',
+					'gen_ai.agent.name': 'planner',
+					'gen_ai.usage.input_tokens': '120',
+					'gen_ai.usage.output_tokens': 30,
+					'signoz.gen_ai.usage.tokens.cost': '0.00000056',
+				}),
+			),
+		).toStrictEqual({
+			model: 'gpt-4o',
+			toolName: 'search',
+			agentName: 'planner',
+			usage: {
+				inputTokens: 120,
+				outputTokens: 30,
+				cacheReadTokens: undefined,
+				cacheCreationTokens: undefined,
+				cost: 0.00000056,
+			},
+		});
+	});
+});
+
+describe('SpanTooltipContent', () => {
+	it('renders status, start and duration for a non-AI span', () => {
+		render(<SpanTooltipContent {...baseProps} />);
+
+		expect(screen.getByText('chat gpt-4o')).toBeInTheDocument();
+		expect(screen.getByText('ok')).toBeInTheDocument();
+		expect(screen.getByText('268 ms')).toBeInTheDocument();
+		expect(screen.getByText('1.11 s')).toBeInTheDocument();
+		expect(screen.queryByText('Usage Breakdown')).not.toBeInTheDocument();
+	});
+
+	it('renders raw input, cache and output tokens with cost', () => {
+		render(
+			<SpanTooltipContent
+				{...baseProps}
+				ai={{
+					model: 'gpt-4o',
+					usage: {
+						inputTokens: 1000,
+						outputTokens: 200,
+						cacheReadTokens: 600,
+						cacheCreationTokens: 100,
+						cost: 0.00000056,
+					},
+				}}
+			/>,
+		);
+
+		expect(screen.getByText('Usage Breakdown')).toBeInTheDocument();
+		expect(screen.getByText('Input')).toBeInTheDocument();
+		expect(screen.getByText('1,000')).toBeInTheDocument();
+		expect(screen.getByText('Cache')).toBeInTheDocument();
+		expect(screen.getByText('Cache read')).toBeInTheDocument();
+		expect(screen.getByText('600')).toBeInTheDocument();
+		expect(screen.getByText('Cache write')).toBeInTheDocument();
+		expect(screen.getByText('100')).toBeInTheDocument();
+		expect(screen.getByText('Output')).toBeInTheDocument();
+		expect(screen.getByText('200')).toBeInTheDocument();
+		// Raw values only: no derived input or total usage.
+		expect(screen.queryByText('1,700')).not.toBeInTheDocument();
+		expect(screen.queryByText('1,200')).not.toBeInTheDocument();
+		expect(screen.getByText('$ 0.00000056')).toBeInTheDocument();
+	});
+
+	it('hides a zero cache row, and the cache group when both are zero', () => {
+		const { rerender } = render(
+			<SpanTooltipContent
+				{...baseProps}
+				ai={{
+					usage: {
+						inputTokens: 194,
+						outputTokens: 32,
+						cacheReadTokens: 50,
+						cacheCreationTokens: 0,
+					},
+				}}
+			/>,
+		);
+
+		expect(screen.getByText('Cache read')).toBeInTheDocument();
+		expect(screen.queryByText('Cache write')).not.toBeInTheDocument();
+
+		rerender(
+			<SpanTooltipContent
+				{...baseProps}
+				ai={{
+					usage: {
+						inputTokens: 194,
+						outputTokens: 32,
+						cacheReadTokens: 0,
+						cacheCreationTokens: 0,
+					},
+				}}
+			/>,
+		);
+
+		expect(screen.queryByText('Cache')).not.toBeInTheDocument();
+		expect(screen.queryByText('Cache read')).not.toBeInTheDocument();
+	});
+
+	it('hides cache rows and cost when the attributes are absent', () => {
+		render(
+			<SpanTooltipContent
+				{...baseProps}
+				ai={{ usage: { inputTokens: 10, outputTokens: 5 } }}
+			/>,
+		);
+
+		expect(screen.queryByText('Cache')).not.toBeInTheDocument();
+		expect(screen.queryByText('Cache read')).not.toBeInTheDocument();
+		expect(screen.queryByText('Cache write')).not.toBeInTheDocument();
+		expect(screen.queryByText('cost')).not.toBeInTheDocument();
+	});
+});

frontend/src/pages/TraceDetailsV3/SpanHoverCard/aiUsage.ts

@@ -0,0 +1,86 @@
+import { SpanV3 } from 'types/api/trace/getTraceV3';
+
+import { GEN_AI_KEYS, getGenAiValue } from '../utils/genAi';
+
+export interface TokenUsage {
+	input: number;
+	output: number;
+	cacheRead?: number;
+	cacheWrite?: number;
+	reasoning?: number;
+}
+
+export interface SpanAiUsage {
+	inputTokens?: number;
+	outputTokens?: number;
+	cacheReadTokens?: number;
+	cacheCreationTokens?: number;
+	cost?: number;
+}
+
+export interface SpanAiDetails {
+	model?: string;
+	toolName?: string;
+	agentName?: string;
+	usage?: SpanAiUsage;
+}
+
+function getGenAiAttributeAsString(
+	span: SpanV3,
+	key: string,
+): string | undefined {
+	const value = getGenAiValue(span, key);
+	return value === undefined ? undefined : String(value);
+}
+
+function getGenAiAttributeAsNumber(
+	span: SpanV3,
+	key: string,
+): number | undefined {
+	const value = getGenAiValue(span, key);
+	if (value === undefined) {
+		return undefined;
+	}
+	const parsed = Number(value);
+	return Number.isFinite(parsed) ? parsed : undefined;
+}
+
+export function getSpanAiDetails(span: SpanV3): SpanAiDetails | undefined {
+	const usage: SpanAiUsage = {
+		inputTokens: getGenAiAttributeAsNumber(span, GEN_AI_KEYS.inputTokens),
+		outputTokens: getGenAiAttributeAsNumber(span, GEN_AI_KEYS.outputTokens),
+		cacheReadTokens: getGenAiAttributeAsNumber(span, GEN_AI_KEYS.cacheReadTokens),
+		cacheCreationTokens: getGenAiAttributeAsNumber(
+			span,
+			GEN_AI_KEYS.cacheCreationTokens,
+		),
+		cost: getGenAiAttributeAsNumber(span, GEN_AI_KEYS.cost),
+	};
+	const hasUsage =
+		usage.inputTokens !== undefined || usage.outputTokens !== undefined;
+
+	const details: SpanAiDetails = {
+		model: getGenAiAttributeAsString(span, GEN_AI_KEYS.requestModel),
+		toolName: getGenAiAttributeAsString(span, GEN_AI_KEYS.toolName),
+		agentName: getGenAiAttributeAsString(span, GEN_AI_KEYS.agentName),
+		usage: hasUsage ? usage : undefined,
+	};
+
+	return details.model || details.toolName || details.agentName || hasUsage
+		? details
+		: undefined;
+}
+
+export function getSpanTokenUsage(span: SpanV3): TokenUsage | undefined {
+	const usage = getSpanAiDetails(span)?.usage;
+	if (!usage) {
+		return undefined;
+	}
+	return {
+		input: usage.inputTokens ?? 0,
+		output: usage.outputTokens ?? 0,
+		cacheRead: usage.cacheReadTokens,
+		cacheWrite: usage.cacheCreationTokens,
+		reasoning: getGenAiAttributeAsNumber(span, GEN_AI_KEYS.reasoningTokens),
+	};
+}

frontend/src/pages/TraceDetailsV3/SpanMessages/MessagesSection.tsx

@@ -0,0 +1,67 @@
+import AIThreadMessage, {
+	AIThreadMessageProps,
+} from '../AIThreadMessage/AIThreadMessage';
+import { ThreadMessage, ThreadView } from '../TraceDetailsThread/types';
+import RawMessages from './RawMessages';
+import { RawMessagesValue } from './utils';
+
+import styles from './SpanMessages.module.scss';
+
+type MessageProps = Pick<
+	AIThreadMessageProps,
+	'isOutput' | 'isToolLinkEnabled' | 'onToolLinkClick'
+>;
+
+interface MessagesSectionProps extends MessageProps {
+	title?: string;
+	view: ThreadView;
+	messages: ThreadMessage[];
+	raw?: RawMessagesValue;
+	testId: string;
+}
+
+function MessagesSection({
+	title,
+	view,
+	messages,
+	raw,
+	testId,
+	isOutput,
+	isToolLinkEnabled,
+	onToolLinkClick,
+}: MessagesSectionProps): JSX.Element | null {
+	const isFormatted = view === ThreadView.Formatted;
+	if (isFormatted ? messages.length === 0 : !raw) {
+		return null;
+	}
+
+	return (
+		<section className={styles.section} data-testid={testId}>
+			{title && <div className={styles.sectionTitle}>{title}</div>}
+			{isFormatted ? (
+				<div className={styles.messages}>
+					{messages.map((message, index) => (
+						<AIThreadMessage
+							// Messages have no stable id and never reorder.
+							// eslint-disable-next-line react/no-array-index-key
+							key={index}
+							message={message}
+							isOutput={isOutput}
+							isToolLinkEnabled={isToolLinkEnabled}
+							onToolLinkClick={onToolLinkClick}
+						/>
+					))}
+				</div>
+			) : (
+				<RawMessages value={raw as RawMessagesValue} />
+			)}
+		</section>
+	);
+}
+
+MessagesSection.defaultProps = {
+	title: undefined,
+	raw: undefined,
+};
+
+export default MessagesSection;

frontend/src/pages/TraceDetailsV3/SpanMessages/RawMessages.tsx

@@ -0,0 +1,21 @@
+import JsonBlock from '../AIThreadMessage/JsonBlock';
+import { RawMessagesValue } from './utils';
+
+import styles from './SpanMessages.module.scss';
+
+interface RawMessagesProps {
+	value: RawMessagesValue;
+}
+
+function RawMessages({ value }: RawMessagesProps): JSX.Element {
+	if (typeof value === 'object') {
+		return <JsonBlock data={value} />;
+	}
+	return (
+		<pre className={styles.raw} data-testid="span-raw-messages">
+			{value}
+		</pre>
+	);
+}
+
+export default RawMessages;

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

@@ -0,0 +1,49 @@
+.root {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-10);
+	min-width: 0;
+}
+
+.section {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-2);
+	min-width: 0;
+}
+
+.sectionTitle {
+	display: flex;
+	align-items: center;
+	gap: var(--spacing-3);
+	font-size: var(--font-size-xs);
+	font-weight: var(--font-weight-medium);
+	color: var(--l2-foreground);
+}
+
+.messages {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-10);
+	min-width: 0;
+}
+
+.raw {
+	margin: 0;
+	padding: var(--spacing-4) var(--spacing-6);
+	border: 1px solid var(--l2-border);
+	border-radius: var(--radius-2);
+	background: var(--l2-background);
+	font-family: var(--font-family-sf-mono);
+	font-size: var(--font-size-xs);
+	line-height: var(--line-height-18);
+	color: var(--l1-foreground);
+	white-space: pre-wrap;
+	word-break: break-all;
+}
+
+.missing {
+	font-size: var(--periscope-font-size-base);
+	font-style: italic;
+	color: var(--l2-foreground);
+}

frontend/src/pages/TraceDetailsV3/SpanMessages/SpanMessages.tsx

@@ -0,0 +1,67 @@
+import { useMemo } from 'react';
+import cx from 'classnames';
+
+import { AIThreadMessageProps } from '../AIThreadMessage/AIThreadMessage';
+import { ThreadSpan, ThreadView } from '../TraceDetailsThread/types';
+import MessagesSection from './MessagesSection';
+import { getSpanMessages, hasAnyMessages } from './utils';
+
+import styles from './SpanMessages.module.scss';
+
+interface SpanMessagesProps extends Pick<
+	AIThreadMessageProps,
+	'isToolLinkEnabled' | 'onToolLinkClick'
+> {
+	span: ThreadSpan;
+	view: ThreadView;
+	className?: string;
+}
+
+/** Input and output messages of one AI span, shared by Thread and Span Details. */
+function SpanMessages({
+	span,
+	view,
+	className,
+	isToolLinkEnabled,
+	onToolLinkClick,
+}: SpanMessagesProps): JSX.Element {
+	const data = useMemo(() => getSpanMessages(span), [span]);
+	const isFormatted = view === ThreadView.Formatted;
+	const callbacks = { isToolLinkEnabled, onToolLinkClick };
+
+	if (!hasAnyMessages(data)) {
+		return (
+			<div className={styles.missing}>
+				This span has no input or output messages.
+			</div>
+		);
+	}
+
+	return (
+		<div className={cx(styles.root, className)}>
+			<MessagesSection
+				title={isFormatted ? undefined : 'Input'}
+				view={view}
+				messages={data.formattedInput}
+				raw={data.rawInput}
+				testId="span-messages-input"
+				{...callbacks}
+			/>
+			<MessagesSection
+				title={isFormatted ? undefined : 'Output'}
+				view={view}
+				messages={data.formattedOutput}
+				raw={data.rawOutput}
+				isOutput
+				testId="span-messages-output"
+				{...callbacks}
+			/>
+		</div>
+	);
+}
+
+SpanMessages.defaultProps = {
+	className: undefined,
+};
+
+export default SpanMessages;

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

@@ -0,0 +1,92 @@
+import { parseJsonObject } from '../AIThreadMessage/utils';
+import {
+	MessagePart,
+	ThreadMessage,
+	ThreadSpan,
+} from '../TraceDetailsThread/types';
+import { GEN_AI_KEYS } from '../utils/genAi';
+
+/** Parsed JSON, or the original string when it isn't JSON. */
+export type RawMessagesValue = object | string;
+
+export interface SpanMessagesData {
+	formattedInput: ThreadMessage[];
+	formattedOutput: ThreadMessage[];
+	rawInput?: RawMessagesValue;
+	rawOutput?: RawMessagesValue;
+}
+
+function toRawValue(value: unknown): RawMessagesValue | undefined {
+	if (value === undefined || value === null || value === '') {
+		return undefined;
+	}
+	if (typeof value === 'string') {
+		return parseJsonObject(value) ?? value;
+	}
+	return typeof value === 'object' ? value : JSON.stringify(value);
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+	return typeof value === 'object' && value !== null && !Array.isArray(value);
+}
+
+function toFallbackPart(part: unknown): MessagePart {
+	if (typeof part === 'string') {
+		return { type: 'text', content: part };
+	}
+	if (isRecord(part) && part.type === 'text') {
+		const text = part.text ?? part.content;
+		if (typeof text === 'string') {
+			return { type: 'text', content: text };
+		}
+	}
+	return { type: 'generic', content: JSON.stringify(part, null, 2) };
+}
+
+function toFallbackMessage(item: unknown): ThreadMessage {
+	if (!isRecord(item)) {
+		return { content: [toFallbackPart(item)] };
+	}
+	const body = item.parts ?? item.content;
+	return {
+		role: typeof item.role === 'string' ? item.role : undefined,
+		content: Array.isArray(body)
+			? body.map(toFallbackPart)
+			: [toFallbackPart(body ?? item)],
+	};
+}
+
+/** Best-effort messages from a raw `gen_ai.*.messages` value. */
+function toFallbackMessages(raw?: RawMessagesValue): ThreadMessage[] {
+	if (raw === undefined) {
+		return [];
+	}
+	return Array.isArray(raw)
+		? raw.map(toFallbackMessage)
+		: [toFallbackMessage(raw)];
+}
+
+export function getSpanMessages(span: ThreadSpan): SpanMessagesData {
+	const rawInput = toRawValue(span.attributes?.[GEN_AI_KEYS.inputMessages]);
+	const rawOutput = toRawValue(span.attributes?.[GEN_AI_KEYS.outputMessages]);
+
+	// TODO: drop the raw-key fallback once the thread API sends formatted_input/output (#13003).
+	return {
+		formattedInput: span.formatted_input?.length
+			? span.formatted_input
+			: toFallbackMessages(rawInput),
+		formattedOutput: span.formatted_output?.length
+			? span.formatted_output
+			: toFallbackMessages(rawOutput),
+		rawInput,
+		rawOutput,
+	};
+}
+
+export function hasFormattedMessages(data: SpanMessagesData): boolean {
+	return data.formattedInput.length > 0 || data.formattedOutput.length > 0;
+}
+
+export function hasAnyMessages(data: SpanMessagesData): boolean {
+	return hasFormattedMessages(data) || !!data.rawInput || !!data.rawOutput;
+}

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

@@ -34,6 +34,15 @@
 	}
 }
 
+.tabs {
+	flex-shrink: 0;
+}
+
+.tab {
+	flex: unset;
+	padding: 0 24px;
+}
+
 .filterSection {
 	display: flex;
 	align-items: center;

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

@@ -1,4 +1,4 @@
-import { useCallback, useState } from 'react';
+import { useCallback, useEffect, useState } from 'react';
 import { useParams } from 'react-router-dom';
 import { Button } from '@signozhq/ui/button';
 import {
@@ -18,22 +18,26 @@ import KeyValueLabel from 'periscope/components/KeyValueLabel';
 import { TraceDetailV3URLProps } from 'types/api/trace/getTraceV3';
 import { DataSource } from 'types/common/queryBuilder';
 
+import { TraceDetailsTab } from '../constants';
 import { TraceDetailEventKeys, TraceDetailEvents } from '../events';
 import { useTraceDetailLogEvent } from '../hooks/useTraceDetailLogEvent';
+import { useTraceDetailsTab } from '../hooks/useTraceDetailsTab';
 import { useTraceStore } from '../stores/traceStore';
 import TraceDownloadPanel from './TraceDownloadPanel';
 import EntityMetadataRow from '../EntityMetadata/EntityMetadataRow';
 import AnalyticsPanel from '../SpanDetailsPanel/AnalyticsPanel/AnalyticsPanel';
 import Filters from '../TraceWaterfall/TraceWaterfallStates/Success/Filters/Filters';
+import { useTraceDetailsStripInfo } from '../useTraceDetailsStripInfo';
 import MissingSpansBanner from './MissingSpansBanner';
-import TraceOptionsMenu from './TraceOptionsMenu';
 import { useTraceSummary } from './useTraceSummary';
+import TraceDetailsTabs from './TraceDetailsTabs';
+import TraceOptionsMenu from './TraceOptionsMenu';
 
 import styles from './TraceDetailsHeader.module.scss';
 import { DATE_TIME_FORMATS } from 'constants/dateTimeFormats';
 
 interface TraceDetailsHeaderProps {
-	onFilteredSpansChange: (spanIds: string[], isFilterActive: boolean) => void;
+	onFilteredSpansChange?: (spanIds: string[], isFilterActive: boolean) => void;
 	showTraceDetailsHeaderOptions?: boolean;
 }
 
@@ -65,6 +69,14 @@ function TraceDetailsHeader({
 	const [isPreviewFieldsOpen, setIsPreviewFieldsOpen] = useState(false);
 	const [isAnalyticsOpen, setIsAnalyticsOpen] = useState(false);
 	const { data: traceSummary } = useTraceSummary(traceID || '');
+	const [tab] = useTraceDetailsTab();
+	const isOverview = tab === TraceDetailsTab.Overview;
+
+	// Overview-only panels must not linger over another tab.
+	useEffect(() => {
+		setIsPreviewFieldsOpen(false);
+		setIsAnalyticsOpen(false);
+	}, [tab]);
 	const previewFields = useTraceStore((s) => s.previewFields);
 	const setPreviewFields = useTraceStore((s) => s.setPreviewFields);
 
@@ -98,13 +110,14 @@ function TraceDetailsHeader({
 		setShowTraceDetails((prev) => !prev);
 	}, []);
 
+	useTraceDetailsStripInfo({
+		totalSpansCount: traceSummary?.totalSpansCount ?? 0,
+		totalErrorSpansCount: traceSummary?.totalErrorSpansCount ?? 0,
+	});
+
 	const startTime = (traceSummary?.startTimestampMillis ?? 0) / 1e3;
 	const endTime = (traceSummary?.endTimestampMillis ?? 0) / 1e3;
 
-	const durationMs = traceSummary
-		? traceSummary.endTimestampMillis - traceSummary.startTimestampMillis
-		: 0;
-
 	return (
 		<div className={styles.wrapper}>
 			<div className={styles.header}>
@@ -125,9 +138,10 @@ function TraceDetailsHeader({
 							badgeValue={traceID || ''}
 							maxCharacters={100}
 						/>
+						<TraceDetailsTabs />
 					</div>
 				)}
-				{showTraceDetailsHeaderOptions && traceSummary && (
+				{isOverview && showTraceDetailsHeaderOptions && traceSummary && (
 					<div
 						className={cx(
 							styles.filterSection,
@@ -181,28 +195,32 @@ function TraceDetailsHeader({
 				)}
 			</div>
 
-			{showTraceDetails && (
+			{(showTraceDetails || !isOverview) && (
 				<div className={styles.subHeader}>
-					{traceSummary ? (
+					{!traceSummary ? (
+						<DetailsLoader />
+					) : (
 						<EntityMetadataRow
 							entity="trace"
 							service={{
 								name: traceSummary.rootServiceName,
 								entryPoint: traceSummary.rootServiceEntryPoint,
 							}}
-							durationMs={durationMs}
+							durationMs={
+								traceSummary.endTimestampMillis - traceSummary.startTimestampMillis
+							}
 							timestamp={dayjs(traceSummary.startTimestampMillis).format(
 								DATE_TIME_FORMATS.DD_MMM_YYYY_HH_MM_SS,
 							)}
 							statusCode={traceSummary.rootSpanStatusCode}
+							tokens={traceSummary.ai?.tokens}
+							cost={traceSummary.ai?.totalCost}
 						/>
-					) : (
-						<DetailsLoader />
 					)}
 				</div>
 			)}
 
-			{traceSummary?.hasMissingSpans && <MissingSpansBanner />}
+			{isOverview && traceSummary?.hasMissingSpans && <MissingSpansBanner />}
 
 			<FieldsSelector
 				isOpen={isPreviewFieldsOpen}

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

@@ -0,0 +1,44 @@
+import { ToggleGroup, ToggleGroupItem } from '@signozhq/ui/toggle-group';
+
+import { TraceDetailsTab } from '../constants';
+import { useTraceDetailsTab } from '../hooks/useTraceDetailsTab';
+
+import styles from './TraceDetailsHeader.module.scss';
+
+function TraceDetailsTabs(): JSX.Element {
+	const [tab, setTab] = useTraceDetailsTab();
+
+	const handleChange = (value: string): void => {
+		// Clicking the active item deselects it and reports ''.
+		if (value) {
+			void setTab(value as TraceDetailsTab);
+		}
+	};
+
+	return (
+		<ToggleGroup
+			type="single"
+			value={tab}
+			onChange={handleChange}
+			className={styles.tabs}
+			size="sm"
+		>
+			<ToggleGroupItem
+				value={TraceDetailsTab.Overview}
+				className={styles.tab}
+				data-testid="trace-details-tab-overview"
+			>
+				Overview
+			</ToggleGroupItem>
+			<ToggleGroupItem
+				value={TraceDetailsTab.Thread}
+				className={styles.tab}
+				data-testid="trace-details-tab-thread"
+			>
+				Thread
+			</ToggleGroupItem>
+		</ToggleGroup>
+	);
+}
+
+export default TraceDetailsTabs;

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

@@ -1,16 +1,45 @@
 import { fireEvent, screen } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 import { getYAxisFormattedValue } from 'components/Graph/yAxisConfig';
+import type { SpantypesGettableTraceSummaryDTO } from 'api/generated/services/sigNoz.schemas';
+import { NuqsTestingAdapter } from 'nuqs/adapters/testing';
 import ROUTES from 'constants/routes';
 import { render } from 'tests/test-utils';
 
 import TraceDetailsHeader from '../TraceDetailsHeader';
 import { useTraceSummary } from '../useTraceSummary';
 
+const MOCK_TRACE_SUMMARY: SpantypesGettableTraceSummaryDTO = {
+	startTimestampMillis: 1_700_000_000_000,
+	endTimestampMillis: 1_700_000_120_000,
+	rootServiceName: '',
+	rootServiceEntryPoint: 'Missing Span',
+	rootSpanStatusCode: '404',
+	totalSpansCount: 3,
+	totalErrorSpansCount: 0,
+	hasMissingSpans: true,
+	ai: {
+		tokens: {
+			input: 12040,
+			output: 3110,
+			cacheRead: 8000,
+			cacheWrite: 1200,
+			reasoning: 900,
+		},
+		totalCost: 0.0421,
+	},
+};
+
 jest.mock('../useTraceSummary', () => ({
-	useTraceSummary: jest.fn(() => ({ data: undefined, isLoading: false })),
+	useTraceSummary: jest.fn(),
 }));
 
+beforeEach(() => {
+	jest
+		.mocked(useTraceSummary)
+		.mockReturnValue({ data: MOCK_TRACE_SUMMARY, isLoading: false });
+});
+
 const mockGoBack = jest.fn();
 const mockPush = jest.fn();
 const mockReplace = jest.fn();
@@ -57,19 +86,10 @@ jest.mock('components/FieldsSelector', () => ({
 
 const baseProps = {
 	onFilteredSpansChange: jest.fn(),
-	showTraceDetailsHeaderOptions: false,
+	showTraceDetailsHeaderOptions: true,
 };
 
-const SUMMARY = {
-	startTimestampMillis: 1_700_000_000_000,
-	endTimestampMillis: 1_700_000_120_000,
-	rootServiceName: 'frontend',
-	rootServiceEntryPoint: 'GET /checkout',
-	rootSpanStatusCode: '200',
-	hasMissingSpans: false,
-	totalSpansCount: 3,
-	totalErrorSpansCount: 0,
-};
+const metadataText = /Missing Span/;
 
 describe('TraceDetailsHeader – back button', () => {
 	beforeEach(() => {
@@ -103,29 +123,9 @@ describe('TraceDetailsHeader – back button', () => {
 describe('TraceDetailsHeader – action cluster', () => {
 	beforeEach(() => {
 		mockReplace.mockClear();
-		jest
-			.mocked(useTraceSummary)
-			.mockReturnValue({ data: SUMMARY, isLoading: false });
 	});
 
-	afterEach(() => {
-		jest
-			.mocked(useTraceSummary)
-			.mockReturnValue({ data: undefined, isLoading: false });
-	});
-
-	it('does not render the action buttons until the summary loads', () => {
-		jest
-			.mocked(useTraceSummary)
-			.mockReturnValue({ data: undefined, isLoading: true });
-		render(<TraceDetailsHeader {...baseProps} showTraceDetailsHeaderOptions />);
-
-		expect(
-			screen.queryByRole('button', { name: /^analytics$/i }),
-		).not.toBeInTheDocument();
-	});
-
-	it('does not render the action buttons while data is still loading', () => {
+	it('does not render the action buttons until the trace data has loaded', () => {
 		render(
 			<TraceDetailsHeader {...baseProps} showTraceDetailsHeaderOptions={false} />,
 		);
@@ -138,8 +138,8 @@ describe('TraceDetailsHeader – action cluster', () => {
 		).not.toBeInTheDocument();
 	});
 
-	it('renders Analytics and Settings action buttons once data is loaded', () => {
-		render(<TraceDetailsHeader {...baseProps} showTraceDetailsHeaderOptions />);
+	it('renders Analytics and Settings action buttons', () => {
+		render(<TraceDetailsHeader {...baseProps} />);
 
 		expect(
 			screen.getByRole('button', { name: /^analytics$/i }),
@@ -150,7 +150,7 @@ describe('TraceDetailsHeader – action cluster', () => {
 	});
 
 	it('toggles the AnalyticsPanel open state when the Analytics button is clicked', () => {
-		render(<TraceDetailsHeader {...baseProps} showTraceDetailsHeaderOptions />);
+		render(<TraceDetailsHeader {...baseProps} />);
 
 		const panel = screen.getByTestId('analytics-panel');
 		expect(panel).toHaveAttribute('data-open', 'false');
@@ -166,70 +166,171 @@ describe('TraceDetailsHeader – action cluster', () => {
 });
 
 describe('TraceDetailsHeader – trace metadata row', () => {
-	// useTraceSummary is mocked, so no API call is made.
-	const traceMetadata = {
-		startTimestampMillis: 1_700_000_000_000,
-		endTimestampMillis: 1_700_000_120_000, // +120000ms = 2 min
-		rootServiceName: 'inventory-frontend',
-		rootServiceEntryPoint: 'large-trace-root',
-		rootSpanStatusCode: '404',
-		hasMissingSpans: false,
-		totalSpansCount: 42,
-		totalErrorSpansCount: 0,
-	};
+	it('shows skeletons instead of the metadata while the summary loads', () => {
+		jest
+			.mocked(useTraceSummary)
+			.mockReturnValue({ data: undefined, isLoading: true });
+		const { container } = render(<TraceDetailsHeader {...baseProps} />);
 
-	const mockSummary = (data?: typeof traceMetadata): void => {
-		jest.mocked(useTraceSummary).mockReturnValue({ data, isLoading: false });
-	};
-
-	afterEach(() => {
-		mockSummary(undefined);
+		expect(screen.queryByText(metadataText)).not.toBeInTheDocument();
+		expect(container.querySelectorAll('.ant-skeleton-input')).toHaveLength(3);
 	});
 
-	it('renders the metadata (service, entry point, duration, status) when provided', () => {
-		mockSummary(traceMetadata);
-		render(<TraceDetailsHeader {...baseProps} showTraceDetailsHeaderOptions />);
+	it('renders the summary metadata with tokens and cost', () => {
+		render(<TraceDetailsHeader {...baseProps} />);
 
-		expect(screen.getByText(/inventory-frontend/)).toBeInTheDocument();
-		expect(screen.getByText('large-trace-root')).toBeInTheDocument();
-		expect(screen.getByText('404')).toBeInTheDocument();
-		// Duration goes through the shared formatter (e.g. "2 min").
+		const { startTimestampMillis, endTimestampMillis } = MOCK_TRACE_SUMMARY;
 		const duration = getYAxisFormattedValue(
-			`${traceMetadata.endTimestampMillis - traceMetadata.startTimestampMillis}`,
+			`${endTimestampMillis - startTimestampMillis}`,
 			'ms',
 		);
+
+		expect(screen.getByText(metadataText)).toBeInTheDocument();
 		expect(screen.getByText(duration)).toBeInTheDocument();
+		expect(screen.getByText('Tokens: 12,040 → 3,110')).toBeInTheDocument();
+		expect(screen.getByText('Cost — $ 0.0421')).toBeInTheDocument();
+	});
+
+	it('renders the root span status code', () => {
+		render(<TraceDetailsHeader {...baseProps} />);
+
+		expect(screen.getByText('404')).toBeInTheDocument();
+	});
+
+	it('omits AI tokens and cost when the summary has no ai field', () => {
+		jest.mocked(useTraceSummary).mockReturnValue({
+			data: { ...MOCK_TRACE_SUMMARY, ai: undefined },
+			isLoading: false,
+		});
+		render(<TraceDetailsHeader {...baseProps} />);
+
+		expect(screen.queryByText(/^Tokens:/)).not.toBeInTheDocument();
+		expect(screen.queryByText(/^Cost —/)).not.toBeInTheDocument();
+	});
+
+	it('omits AI tokens when input and output are both zero', () => {
+		jest.mocked(useTraceSummary).mockReturnValue({
+			data: {
+				...MOCK_TRACE_SUMMARY,
+				ai: {
+					totalCost: 0.0421,
+					tokens: {
+						input: 0,
+						output: 0,
+						cacheRead: 8000,
+						cacheWrite: 1200,
+						reasoning: 900,
+					},
+				},
+			},
+			isLoading: false,
+		});
+		render(<TraceDetailsHeader {...baseProps} />);
+
+		expect(screen.queryByText(/^Tokens:/)).not.toBeInTheDocument();
+		expect(screen.getByText('Cost — $ 0.0421')).toBeInTheDocument();
+	});
+
+	it('shows skeletons instead of the metadata when the summary is absent', () => {
+		jest
+			.mocked(useTraceSummary)
+			.mockReturnValue({ data: undefined, isLoading: false });
+		const { container } = render(<TraceDetailsHeader {...baseProps} />);
+
+		expect(screen.queryByText(metadataText)).not.toBeInTheDocument();
+		expect(container.querySelectorAll('.ant-skeleton-input')).toHaveLength(3);
 	});
 
 	it('is shown by default and can be hidden / shown again via the Trace options menu', async () => {
 		const user = userEvent.setup({ delay: null });
-		mockSummary(traceMetadata);
-		render(<TraceDetailsHeader {...baseProps} showTraceDetailsHeaderOptions />);
+		render(<TraceDetailsHeader {...baseProps} />);
 
-		// Visible by default (showTraceDetails defaults to true).
-		expect(screen.getByText(/inventory-frontend/)).toBeInTheDocument();
+		expect(screen.getByText(metadataText)).toBeInTheDocument();
 
-		// Hide it.
 		await user.click(screen.getByRole('button', { name: /trace options/i }));
 		await user.click(
 			await screen.findByRole('menuitem', { name: /hide trace details/i }),
 		);
-		expect(screen.queryByText(/inventory-frontend/)).not.toBeInTheDocument();
+		expect(screen.queryByText(metadataText)).not.toBeInTheDocument();
 
-		// Show it again.
 		await user.click(screen.getByRole('button', { name: /trace options/i }));
 		await user.click(
 			await screen.findByRole('menuitem', { name: /show trace details/i }),
 		);
-		expect(screen.getByText(/inventory-frontend/)).toBeInTheDocument();
-	});
-
-	it('shows skeletons instead of the metadata when the summary is absent', () => {
-		const { container } = render(
-			<TraceDetailsHeader {...baseProps} showTraceDetailsHeaderOptions />,
-		);
-
-		expect(screen.queryByText(/inventory-frontend/)).not.toBeInTheDocument();
-		expect(container.querySelectorAll('.ant-skeleton-input')).toHaveLength(3);
+		expect(screen.getByText(metadataText)).toBeInTheDocument();
+	});
+});
+
+describe('TraceDetailsHeader – tabs', () => {
+	// In-memory URL state, so a tab switch can't leak into the next test.
+	const renderHeader = (): void => {
+		render(
+			<NuqsTestingAdapter hasMemory>
+				<TraceDetailsHeader {...baseProps} />
+			</NuqsTestingAdapter>,
+		);
+	};
+
+	it('shows the Overview-only sections on the Overview tab', () => {
+		renderHeader();
+
+		expect(screen.getByTestId('filters-stub')).toBeInTheDocument();
+		expect(
+			screen.getByRole('button', { name: /^analytics$/i }),
+		).toBeInTheDocument();
+		expect(
+			screen.getByRole('button', { name: /trace options/i }),
+		).toBeInTheDocument();
+		expect(screen.getByTestId('missing-spans-banner')).toBeInTheDocument();
+	});
+
+	it('keeps only the metadata row on the Thread tab', async () => {
+		const user = userEvent.setup({ delay: null });
+		renderHeader();
+
+		await user.click(screen.getByTestId('trace-details-tab-thread'));
+
+		expect(screen.queryByTestId('filters-stub')).not.toBeInTheDocument();
+		expect(
+			screen.queryByRole('button', { name: /^analytics$/i }),
+		).not.toBeInTheDocument();
+		expect(
+			screen.queryByRole('button', { name: /trace options/i }),
+		).not.toBeInTheDocument();
+		expect(screen.queryByTestId('missing-spans-banner')).not.toBeInTheDocument();
+		expect(screen.getByText(metadataText)).toBeInTheDocument();
+	});
+
+	it('shows the metadata row on the Thread tab even when hidden on Overview', async () => {
+		const user = userEvent.setup({ delay: null });
+		renderHeader();
+
+		await user.click(screen.getByRole('button', { name: /trace options/i }));
+		await user.click(
+			await screen.findByRole('menuitem', { name: /hide trace details/i }),
+		);
+		expect(screen.queryByText(metadataText)).not.toBeInTheDocument();
+
+		await user.click(screen.getByTestId('trace-details-tab-thread'));
+
+		expect(screen.getByText(metadataText)).toBeInTheDocument();
+	});
+
+	it('closes the Analytics panel when switching to the Thread tab', async () => {
+		const user = userEvent.setup({ delay: null });
+		renderHeader();
+
+		await user.click(screen.getByRole('button', { name: /^analytics$/i }));
+		expect(screen.getByTestId('analytics-panel')).toHaveAttribute(
+			'data-open',
+			'true',
+		);
+
+		await user.click(screen.getByTestId('trace-details-tab-thread'));
+
+		expect(screen.getByTestId('analytics-panel')).toHaveAttribute(
+			'data-open',
+			'false',
+		);
 	});
 });

frontend/src/pages/TraceDetailsV3/TraceDetailsHeader/useTraceSummary.ts

@@ -9,7 +9,7 @@ interface UseTraceSummaryResult {
 export function useTraceSummary(traceId: string): UseTraceSummaryResult {
 	const { data, isLoading } = useGetTraceSummary(
 		{ traceID: traceId },
-		{ query: { enabled: !!traceId, keepPreviousData: true } },
+		{ query: { enabled: !!traceId } },
 	);
 
 	return { data: data?.data, isLoading };

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

@@ -1,10 +1,3 @@
-.root {
-	flex: 1;
-	min-height: 0;
-	display: flex;
-	flex-direction: column;
-}
-
 .layoutRow {
 	display: flex;
 	flex: 1;

frontend/src/pages/TraceDetailsV3/TraceDetailsOverview/TraceDetailsOverview.tsx

@@ -0,0 +1,495 @@
+/* eslint-disable sonarjs/cognitive-complexity */
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
+import { useParams } from 'react-router-dom';
+import {
+	ChartNoAxesGantt,
+	ChevronDown,
+	ChevronRight,
+	Info,
+	TriangleAlert,
+} from '@signozhq/icons';
+import getLocalStorageKey from 'api/browser/localstorage/get';
+import { Collapse } from 'antd';
+import { useDetailsPanel } from 'components/DetailsPanel';
+import WarningPopover from 'components/WarningPopover/WarningPopover';
+import { LOCALSTORAGE } from 'constants/localStorage';
+import useGetTraceV4 from 'hooks/trace/useGetTraceV4';
+import { useSafeNavigate } from 'hooks/useSafeNavigate';
+import useUrlQuery from 'hooks/useUrlQuery';
+import { getUnstableCurrentSearchParams } from 'utils/getUnstableCurrentSearchParams';
+import { ResizableBox } from 'periscope/components/ResizableBox';
+import { SpanV3, TraceDetailV3URLProps } from 'types/api/trace/getTraceV3';
+
+import { TraceDetailEventKeys, TraceDetailEvents } from '../events';
+import { useSpanDetailVariant } from '../hooks/useSpanDetailVariant';
+import { useTraceDetailLogEvent } from '../hooks/useTraceDetailLogEvent';
+import NoData from '../NoData/NoData';
+import {
+	setTraceStoreAvailableColorByFields,
+	useTraceStore,
+} from '../stores/traceStore';
+import { SpanDetailVariant } from '../SpanDetailsPanel/constants';
+import SpanDetailsPanel from '../SpanDetailsPanel/SpanDetailsPanel';
+import { FLAMEGRAPH_SPAN_LIMIT } from '../TraceFlamegraph/constants';
+import TraceFlamegraph from '../TraceFlamegraph/TraceFlamegraph';
+import TraceWaterfall from '../TraceWaterfall/TraceWaterfall';
+import { IInterestedSpan } from '../TraceWaterfall/types';
+import { getAncestorSpanIds } from '../TraceWaterfall/utils';
+import { getAvailableColorByFieldNames } from '../utils';
+
+import cx from 'classnames';
+
+import styles from './TraceDetailsOverview.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} />;
+}
+
+interface TraceDetailsOverviewProps {
+	filteredSpanIds: string[];
+	isFilterActive: boolean;
+	onHasTraceDataChange: (hasTraceData: boolean) => void;
+}
+
+function TraceDetailsOverview({
+	filteredSpanIds,
+	isFilterActive,
+	onHasTraceDataChange,
+}: TraceDetailsOverviewProps): JSX.Element {
+	const { id: traceId } = useParams<TraceDetailV3URLProps>();
+	const urlQuery = useUrlQuery();
+	const [interestedSpanId, setInterestedSpanId] = useState<IInterestedSpan>(
+		() => ({
+			spanId: urlQuery.get('spanId') || '',
+			isUncollapsed: urlQuery.get('spanId') !== '',
+		}),
+	);
+	const [uncollapsedNodes, setUncollapsedNodes] = useState<string[]>([]);
+	const [localUncollapsedNodes, setLocalUncollapsedNodes] = useState<
+		Set<string>
+	>(new Set());
+	const [selectedSpan, setSelectedSpan] = useState<SpanV3>();
+
+	const selectedSpanId = urlQuery.get('spanId') || undefined;
+	const { safeNavigate } = useSafeNavigate();
+
+	const logTraceEvent = useTraceDetailLogEvent('v3', traceId || '');
+	// Tracks which traceId the load event already fired for, so navigating
+	// between traces (the route component stays mounted) re-fires it once each.
+	const dataLoadedFiredForRef = useRef('');
+	const colorByField = useTraceStore((s) => s.colorByField);
+	const previewFieldsCount = useTraceStore((s) => s.previewFields.length);
+	const userPrefsReady = useTraceStore((s) => s.userPreferences !== null);
+
+	const handleSpanDetailsClose = useCallback((): void => {
+		const params = getUnstableCurrentSearchParams();
+		params.delete('spanId');
+		safeNavigate({ search: params.toString() }, { replace: true });
+	}, [safeNavigate]);
+
+	const panelState = useDetailsPanel({
+		entityId: selectedSpanId,
+		onClose: handleSpanDetailsClose,
+	});
+
+	const allSpansRef = useRef<SpanV3[]>([]);
+	const deepLinkResolvedRef = useRef(false);
+
+	// Refetch only when the URL target isn't already loaded. Keeps row clicks
+	// and other in-window URL navigation from triggering a backend window slide.
+	useEffect(() => {
+		const spanId = urlQuery.get('spanId') || '';
+		if (!spanId) {
+			return;
+		}
+		const idx = allSpansRef.current.findIndex((s) => s.span_id === spanId);
+		if (idx !== -1) {
+			setSelectedSpan(allSpansRef.current[idx]);
+			return;
+		}
+		setInterestedSpanId({ spanId, isUncollapsed: true });
+	}, [urlQuery]);
+
+	// Once all spans are loaded (frontend mode), freeze query params so
+	// subsequent interestedSpanId changes don't trigger unnecessary refetches.
+	const fullDataLoadedRef = useRef(false);
+	const frozenParamsRef = useRef({
+		selectedSpanId: interestedSpanId.spanId,
+		isSelectedSpanIDUnCollapsed: interestedSpanId.isUncollapsed,
+		uncollapsedSpans: uncollapsedNodes,
+	});
+
+	const queryParams = fullDataLoadedRef.current
+		? frozenParamsRef.current
+		: {
+				selectedSpanId: interestedSpanId.spanId,
+				isSelectedSpanIDUnCollapsed: interestedSpanId.isUncollapsed,
+				uncollapsedSpans: uncollapsedNodes,
+			};
+
+	const {
+		data: traceData,
+		isFetching: isFetchingTraceData,
+		error: errorFetchingTraceData,
+	} = useGetTraceV4({
+		traceId,
+		uncollapsedSpans: queryParams.uncollapsedSpans,
+		selectedSpanId: queryParams.selectedSpanId,
+		isSelectedSpanIDUnCollapsed: queryParams.isSelectedSpanIDUnCollapsed,
+	});
+
+	const allSpans = traceData?.payload?.spans || [];
+	const totalSpansCount = traceData?.payload?.totalSpansCount || 0;
+
+	const isFullDataLoaded =
+		totalSpansCount > 0 && totalSpansCount <= allSpans.length;
+
+	// Color-by options, gated on fields in loaded spans. Resource attrs are
+	// trace-wide, so any window has the full set — no need to accumulate.
+	const availableColorByFields = useMemo(() => {
+		const spans = traceData?.payload?.spans;
+		return spans?.length ? getAvailableColorByFieldNames(spans) : undefined;
+	}, [traceData?.payload?.spans]);
+
+	useEffect(() => {
+		setTraceStoreAvailableColorByFields(availableColorByFields);
+	}, [availableColorByFields]);
+
+	// Lock the ref once we confirm all data is loaded
+	if (isFullDataLoaded && !fullDataLoadedRef.current) {
+		fullDataLoadedRef.current = true;
+		frozenParamsRef.current = {
+			selectedSpanId: interestedSpanId.spanId,
+			isSelectedSpanIDUnCollapsed: interestedSpanId.isUncollapsed,
+			uncollapsedSpans: uncollapsedNodes,
+		};
+	}
+
+	useEffect(() => {
+		allSpansRef.current = allSpans;
+	}, [allSpans]);
+
+	useEffect(() => {
+		if (
+			!traceId ||
+			dataLoadedFiredForRef.current === traceId ||
+			!userPrefsReady
+		) {
+			return;
+		}
+		const payload = traceData?.payload;
+		if (!payload?.spans?.length) {
+			return;
+		}
+		dataLoadedFiredForRef.current = traceId;
+		const numServices = new Set(payload.spans.map((s) => s['service.name'])).size;
+		logTraceEvent(TraceDetailEvents.DataLoaded, {
+			[TraceDetailEventKeys.TotalSpansCount]: totalSpansCount,
+			[TraceDetailEventKeys.NumServices]: numServices,
+			[TraceDetailEventKeys.TraceDurationMs]:
+				payload.endTimestampMillis - payload.startTimestampMillis,
+			[TraceDetailEventKeys.HadErrors]: (payload.totalErrorSpansCount || 0) > 0,
+			[TraceDetailEventKeys.FlamegraphSampled]:
+				totalSpansCount > FLAMEGRAPH_SPAN_LIMIT,
+			[TraceDetailEventKeys.SpanPanelVariant]:
+				getLocalStorageKey(LOCALSTORAGE.TRACE_DETAILS_SPAN_DETAILS_POSITION) ||
+				SpanDetailVariant.DOCKED_RIGHT,
+			[TraceDetailEventKeys.ColorByField]: colorByField.name,
+			[TraceDetailEventKeys.PreviewFieldsCount]: previewFieldsCount,
+		});
+	}, [
+		traceId,
+		userPrefsReady,
+		traceData,
+		totalSpansCount,
+		colorByField,
+		previewFieldsCount,
+		logTraceEvent,
+	]);
+
+	// Frontend mode: expand all parents by default when full data arrives
+	useEffect(() => {
+		if (isFullDataLoaded && allSpans.length > 0) {
+			const parentIds = new Set(
+				allSpans.filter((s) => s.has_children).map((s) => s.span_id),
+			);
+			setLocalUncollapsedNodes(parentIds);
+		}
+	}, [isFullDataLoaded, allSpans]);
+
+	// Backend mode: sync uncollapsed state from API response
+	useEffect(() => {
+		if (
+			!isFullDataLoaded &&
+			traceData &&
+			traceData.payload &&
+			traceData.payload.uncollapsedSpans
+		) {
+			setUncollapsedNodes(traceData.payload.uncollapsedSpans);
+		}
+	}, [traceData, isFullDataLoaded]);
+
+	// Tracks whether we've already done the initial URL→selectedSpan handoff
+	//Lets `interestedSpanId` stay purely as the refetch trigger in frontend mode.
+	useEffect(() => {
+		if (deepLinkResolvedRef.current) {
+			return;
+		}
+		if (allSpans.length === 0) {
+			return;
+		}
+		if (selectedSpanId) {
+			const span = allSpans.find((s) => s.span_id === selectedSpanId);
+			if (!span) {
+				// Span not in the current window — wait for more data (backend
+				// pagination) before marking resolved.
+				return;
+			}
+			setSelectedSpan(span);
+		} else {
+			setSelectedSpan((prev) => prev ?? allSpans[0]);
+		}
+		deepLinkResolvedRef.current = true;
+	}, [selectedSpanId, allSpans]);
+
+	// Frontend mode: auto-expand ancestors of the URL-targeted span so it's
+	// visible. Keyed on URL `spanId`(selectedSpanId).
+	useEffect(() => {
+		if (!isFullDataLoaded || !selectedSpanId || allSpans.length === 0) {
+			return;
+		}
+		const ancestors = getAncestorSpanIds(allSpans, selectedSpanId);
+		if (ancestors.size === 0) {
+			return;
+		}
+		setLocalUncollapsedNodes((prev) => {
+			// Check if all ancestors are already expanded — avoid unnecessary state update
+			let allPresent = true;
+			for (const id of ancestors) {
+				if (!prev.has(id)) {
+					allPresent = false;
+					break;
+				}
+			}
+			if (allPresent) {
+				return prev;
+			}
+
+			const next = new Set(prev);
+			for (const id of ancestors) {
+				next.add(id);
+			}
+			return next;
+		});
+	}, [isFullDataLoaded, selectedSpanId, allSpans]);
+
+	const [activeKeys, setActiveKeys] = useState<string[]>(['flame', 'waterfall']);
+
+	const handleCollapseChange = (key: string): void => {
+		logTraceEvent(
+			key === 'flame'
+				? TraceDetailEvents.FlameGraphToggled
+				: TraceDetailEvents.WaterfallToggled,
+			{ [TraceDetailEventKeys.Expanded]: !activeKeys.includes(key) },
+		);
+		setActiveKeys((prev) =>
+			prev.includes(key) ? prev.filter((k) => k !== key) : [...prev, key],
+		);
+	};
+
+	const [spanDetailVariant, handleVariantChange] = useSpanDetailVariant();
+
+	const RIGHT_DOCK_MIN = 480;
+	const RIGHT_DOCK_MAX = 720;
+	const [rightDockWidth, setRightDockWidth] = useState(RIGHT_DOCK_MIN);
+
+	const showNoData =
+		!isFetchingTraceData &&
+		(!!errorFetchingTraceData || !traceData?.payload?.spans?.length);
+
+	const hasTraceData = !showNoData && allSpans.length > 0;
+
+	useEffect(() => {
+		onHasTraceDataChange(hasTraceData);
+		return (): void => onHasTraceDataChange(false);
+	}, [hasTraceData, onHasTraceDataChange]);
+
+	const isDocked = spanDetailVariant === SpanDetailVariant.DOCKED;
+	const isRightDocked = spanDetailVariant === SpanDetailVariant.DOCKED_RIGHT;
+	const isWaterfallDocked = panelState.isOpen && isDocked;
+	const showRightDock = panelState.isOpen && isRightDocked;
+
+	const waterfallChildren = (
+		<ResizableBox
+			defaultHeight={300}
+			minHeight={150}
+			disabled={!isWaterfallDocked}
+		>
+			<TraceWaterfall
+				traceData={traceData}
+				isFetchingTraceData={isFetchingTraceData}
+				errorFetchingTraceData={errorFetchingTraceData}
+				traceId={traceId || ''}
+				interestedSpanId={interestedSpanId}
+				setInterestedSpanId={setInterestedSpanId}
+				uncollapsedNodes={uncollapsedNodes}
+				isFullDataLoaded={isFullDataLoaded}
+				localUncollapsedNodes={localUncollapsedNodes}
+				setLocalUncollapsedNodes={setLocalUncollapsedNodes}
+				selectedSpan={selectedSpan}
+				setSelectedSpan={setSelectedSpan}
+				filteredSpanIds={filteredSpanIds}
+				isFilterActive={isFilterActive}
+			/>
+		</ResizableBox>
+	);
+
+	return (
+		<>
+			{showNoData ? (
+				<NoData />
+			) : (
+				<>
+					<div className={styles.layoutRow}>
+						<div className={styles.content}>
+							<Collapse
+								// @ts-expect-error motion is passed through to rc-collapse to disable animation
+								motion={false}
+								activeKey={activeKeys.filter((k) => k === 'flame')}
+								onChange={(): void => handleCollapseChange('flame')}
+								size="small"
+								expandIcon={renderPanelExpandIcon}
+								className={styles.flameCollapse}
+								items={[
+									{
+										key: 'flame',
+										label: (
+											<div className={styles.collapseLabel}>
+												<span className={styles.collapseTitle}>
+													Flame Graph
+													{traceData?.payload?.totalSpansCount &&
+														traceData.payload.totalSpansCount > FLAMEGRAPH_SPAN_LIMIT && (
+															<WarningPopover
+																message="The total span count exceeds the visualization limit. Displaying a sampled subset of spans in flamegraph."
+																placement="bottomLeft"
+															>
+																<Info
+																	size={16}
+																	color="var(--l2-foreground)"
+																	style={{ cursor: 'pointer' }}
+																/>
+															</WarningPopover>
+														)}
+												</span>
+												{traceData?.payload?.totalSpansCount ? (
+													<span className={styles.collapseCount}>
+														<span className={styles.collapseCountItem}>
+															<ChartNoAxesGantt size={13} />
+															Spans: {traceData.payload.totalSpansCount}
+														</span>
+														<span
+															className={cx(styles.collapseCountItem, {
+																[styles.hasErrors]: traceData.payload.totalErrorSpansCount > 0,
+															})}
+														>
+															<TriangleAlert size={13} />
+															Errors:{' '}
+															{traceData.payload.totalErrorSpansCount ?? (
+																<span className="translate-safe">{0}</span>
+															)}
+														</span>
+													</span>
+												) : null}
+											</div>
+										),
+										children: (
+											<ResizableBox defaultHeight={300} minHeight={100} maxHeight={400}>
+												<TraceFlamegraph
+													filteredSpanIds={filteredSpanIds}
+													isFilterActive={isFilterActive}
+													selectedSpan={selectedSpan}
+													totalSpansCount={totalSpansCount}
+												/>
+											</ResizableBox>
+										),
+									},
+								]}
+							/>
+
+							<Collapse
+								// @ts-expect-error motion is passed through to rc-collapse to disable animation
+								motion={false}
+								activeKey={activeKeys.filter((k) => k === 'waterfall')}
+								onChange={(): void => handleCollapseChange('waterfall')}
+								size="small"
+								expandIcon={renderPanelExpandIcon}
+								className={cx(styles.waterfallCollapse, {
+									[styles.isDocked]: isWaterfallDocked,
+								})}
+								items={[
+									{
+										key: 'waterfall',
+										label: 'Waterfall',
+										children: activeKeys.includes('waterfall') ? waterfallChildren : null,
+									},
+								]}
+							/>
+
+							{panelState.isOpen && isDocked && (
+								<div className={styles.dockedSpanDetails}>
+									<SpanDetailsPanel
+										panelState={panelState}
+										selectedSpan={selectedSpan}
+										variant={SpanDetailVariant.DOCKED}
+										onVariantChange={handleVariantChange}
+										traceStartTime={traceData?.payload?.startTimestampMillis}
+										traceEndTime={traceData?.payload?.endTimestampMillis}
+									/>
+								</div>
+							)}
+						</div>
+
+						{showRightDock && (
+							<ResizableBox
+								handle="left"
+								defaultWidth={rightDockWidth}
+								minWidth={RIGHT_DOCK_MIN}
+								maxWidth={RIGHT_DOCK_MAX}
+								onResize={setRightDockWidth}
+								className={styles.rightDock}
+							>
+								<SpanDetailsPanel
+									panelState={panelState}
+									selectedSpan={selectedSpan}
+									variant={SpanDetailVariant.DOCKED_RIGHT}
+									onVariantChange={handleVariantChange}
+									traceStartTime={traceData?.payload?.startTimestampMillis}
+									traceEndTime={traceData?.payload?.endTimestampMillis}
+								/>
+							</ResizableBox>
+						)}
+					</div>
+
+					{panelState.isOpen && spanDetailVariant === SpanDetailVariant.DIALOG && (
+						<SpanDetailsPanel
+							panelState={panelState}
+							selectedSpan={selectedSpan}
+							variant={SpanDetailVariant.DIALOG}
+							onVariantChange={handleVariantChange}
+							traceStartTime={traceData?.payload?.startTimestampMillis}
+							traceEndTime={traceData?.payload?.endTimestampMillis}
+						/>
+					)}
+				</>
+			)}
+		</>
+	);
+}
+
+export default TraceDetailsOverview;

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

@@ -0,0 +1,32 @@
+.root {
+	flex: 1;
+	display: flex;
+	flex-direction: column;
+	align-items: center;
+	justify-content: center;
+	gap: var(--spacing-4);
+	padding: var(--spacing-16);
+	text-align: center;
+}
+
+.icon {
+	color: var(--l2-foreground);
+}
+
+.title {
+	font-size: var(--periscope-font-size-medium);
+	font-weight: var(--font-weight-medium);
+	color: var(--l1-foreground);
+}
+
+.description {
+	max-width: 420px;
+	font-size: var(--periscope-font-size-base);
+	color: var(--l2-foreground);
+}
+
+.actions {
+	display: flex;
+	gap: var(--spacing-4);
+	margin-top: var(--spacing-4);
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/ThreadEmptyState.tsx

@@ -0,0 +1,34 @@
+import { ReactNode } from 'react';
+
+import styles from './ThreadEmptyState.module.scss';
+
+interface ThreadEmptyStateProps {
+	icon: ReactNode;
+	title: string;
+	description: string;
+	actions?: ReactNode;
+	testId: string;
+}
+
+function ThreadEmptyState({
+	icon,
+	title,
+	description,
+	actions,
+	testId,
+}: ThreadEmptyStateProps): JSX.Element {
+	return (
+		<div className={styles.root} data-testid={testId}>
+			<span className={styles.icon}>{icon}</span>
+			<span className={styles.title}>{title}</span>
+			<span className={styles.description}>{description}</span>
+			{actions && <div className={styles.actions}>{actions}</div>}
+		</div>
+	);
+}
+
+ThreadEmptyState.defaultProps = {
+	actions: undefined,
+};
+
+export default ThreadEmptyState;

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

@@ -0,0 +1,40 @@
+.root {
+	display: flex;
+	flex-direction: column;
+	align-items: flex-start;
+	gap: var(--spacing-12);
+	padding: var(--spacing-20) var(--spacing-24);
+}
+
+.message {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-4);
+	max-width: 428px;
+}
+
+.emoji {
+	font-size: 32px;
+	line-height: 1;
+}
+
+.paragraphs {
+	display: flex;
+	flex-direction: column;
+	gap: var(--paragraph-base-500-line-height);
+}
+
+.text {
+	margin: 0;
+	font-family: var(--paragraph-base-500-font-family);
+	font-size: var(--paragraph-base-500-font-size);
+	font-weight: var(--paragraph-base-500-font-weight);
+	line-height: var(--paragraph-base-500-line-height);
+	letter-spacing: var(--paragraph-base-500-letter-spacing);
+	color: var(--l2-foreground);
+}
+
+.highlight {
+	composes: text;
+	color: var(--l1-foreground);
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/ThreadNoAiSpans.tsx

@@ -0,0 +1,41 @@
+import { ArrowRight } from '@signozhq/icons';
+import { Button } from '@signozhq/ui/button';
+import { openInNewTab } from 'utils/navigation';
+
+import { LLM_OBSERVABILITY_DOCS_URL } from '../constants';
+
+import styles from './ThreadNoAiSpans.module.scss';
+
+function ThreadNoAiSpans(): JSX.Element {
+	return (
+		<div className={styles.root} data-testid="thread-empty">
+			<div className={styles.message}>
+				<span className={styles.emoji} aria-hidden>
+					🚏
+				</span>
+				<div className={styles.paragraphs}>
+					<p className={styles.text}>
+						Looks like this trace does not have any spans from AI-related actions.
+					</p>
+					<p className={styles.highlight}>
+						Thread view summarising your entire AI-journey history will appear here
+						when the spans have the necessary datapoints.
+					</p>
+				</div>
+			</div>
+			<Button
+				variant="solid"
+				color="secondary"
+				suffix={<ArrowRight size={12} />}
+				onClick={(): void => {
+					openInNewTab(LLM_OBSERVABILITY_DOCS_URL);
+				}}
+				testId="thread-empty-learn-more"
+			>
+				Learn more
+			</Button>
+		</div>
+	);
+}
+
+export default ThreadNoAiSpans;

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/ThreadPageLoader.tsx

@@ -0,0 +1,17 @@
+import { Skeleton } from '@signozhq/ui/skeleton';
+
+import styles from './ThreadSpanList.module.scss';
+
+interface ThreadPageLoaderProps {
+	testId: string;
+}
+
+function ThreadPageLoader({ testId }: ThreadPageLoaderProps): JSX.Element {
+	return (
+		<div className={styles.pageLoader} data-testid={testId}>
+			<Skeleton active title={{ width: '30%' }} paragraph={{ rows: 2 }} />
+		</div>
+	);
+}
+
+export default ThreadPageLoader;

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

@@ -0,0 +1,16 @@
+.card {
+	padding: var(--spacing-8);
+	border: 1px solid var(--l2-border);
+	border-radius: var(--radius-2);
+	background: var(--l1-background);
+	min-width: 0;
+	cursor: pointer;
+
+	&:hover {
+		border-color: var(--l3-border);
+	}
+
+	&.isSelected {
+		border-color: var(--primary);
+	}
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/ThreadSpanCard.tsx

@@ -0,0 +1,44 @@
+import { memo } from 'react';
+import cx from 'classnames';
+
+import SpanMessages from '../SpanMessages/SpanMessages';
+import { ThreadSpan, ThreadView } from './types';
+
+import styles from './ThreadSpanCard.module.scss';
+
+interface ThreadSpanCardProps {
+	span: ThreadSpan;
+	view: ThreadView;
+	isSelected: boolean;
+	onSelect: (span: ThreadSpan) => void;
+	isToolLinkEnabled: (toolCallId: string) => boolean;
+	onToolLinkClick: (toolCallId: string) => void;
+}
+
+function ThreadSpanCard({
+	span,
+	view,
+	isSelected,
+	onSelect,
+	isToolLinkEnabled,
+	onToolLinkClick,
+}: ThreadSpanCardProps): JSX.Element {
+	return (
+		// eslint-disable-next-line jsx-a11y/click-events-have-key-events, jsx-a11y/no-noninteractive-element-interactions
+		<article
+			className={cx(styles.card, isSelected && styles.isSelected)}
+			onClick={(): void => onSelect(span)}
+			data-span-id={span.span_id}
+			data-testid="thread-span-card"
+		>
+			<SpanMessages
+				span={span}
+				view={view}
+				isToolLinkEnabled={isToolLinkEnabled}
+				onToolLinkClick={onToolLinkClick}
+			/>
+		</article>
+	);
+}
+
+export default memo(ThreadSpanCard);

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/ThreadSpanDetails.tsx

@@ -0,0 +1,80 @@
+import { useState } from 'react';
+import { useParams } from 'react-router-dom';
+import { DetailsPanelState } from 'components/DetailsPanel/types';
+import { ResizableBox } from 'periscope/components/ResizableBox';
+import { TraceDetailV3URLProps } from 'types/api/trace/getTraceV3';
+
+import SpanDetailsPanel from '../SpanDetailsPanel/SpanDetailsPanel';
+import { SpanDetailVariant } from '../SpanDetailsPanel/constants';
+import { useTraceSummary } from '../TraceDetailsHeader/useTraceSummary';
+import { ThreadSpan } from './types';
+
+import styles from './TraceDetailsThread.module.scss';
+
+const RIGHT_DOCK_MIN = 480;
+const RIGHT_DOCK_MAX = 720;
+const BOTTOM_DOCK_DEFAULT = 360;
+const BOTTOM_DOCK_MIN = 200;
+
+interface ThreadSpanDetailsProps {
+	panelState: DetailsPanelState;
+	span: ThreadSpan;
+	variant: SpanDetailVariant;
+	onVariantChange: (variant: SpanDetailVariant) => void;
+}
+
+function ThreadSpanDetails({
+	panelState,
+	span,
+	variant,
+	onVariantChange,
+}: ThreadSpanDetailsProps): JSX.Element {
+	const { id: traceId = '' } = useParams<TraceDetailV3URLProps>();
+	const { data: summary } = useTraceSummary(traceId);
+	const [width, setWidth] = useState(RIGHT_DOCK_MIN);
+	const [height, setHeight] = useState(BOTTOM_DOCK_DEFAULT);
+
+	const panel = (
+		<SpanDetailsPanel
+			panelState={panelState}
+			selectedSpan={span}
+			variant={variant}
+			onVariantChange={onVariantChange}
+			traceStartTime={summary?.startTimestampMillis}
+			traceEndTime={summary?.endTimestampMillis}
+		/>
+	);
+
+	if (variant === SpanDetailVariant.DOCKED_RIGHT) {
+		return (
+			<ResizableBox
+				handle="left"
+				defaultWidth={width}
+				minWidth={RIGHT_DOCK_MIN}
+				maxWidth={RIGHT_DOCK_MAX}
+				onResize={setWidth}
+				className={styles.rightDock}
+			>
+				{panel}
+			</ResizableBox>
+		);
+	}
+
+	if (variant === SpanDetailVariant.DOCKED) {
+		return (
+			<ResizableBox
+				handle="top"
+				defaultHeight={height}
+				minHeight={BOTTOM_DOCK_MIN}
+				onResize={setHeight}
+				className={styles.bottomDock}
+			>
+				{panel}
+			</ResizableBox>
+		);
+	}
+
+	return panel;
+}
+
+export default ThreadSpanDetails;

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

@@ -0,0 +1,23 @@
+.list {
+	flex: 1;
+	min-height: 0;
+	overflow-y: auto;
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-6);
+	padding: var(--spacing-6) var(--spacing-8);
+	// Prepend compensation is manual; native anchoring would double-shift.
+	overflow-anchor: none;
+}
+
+.sentinel {
+	flex-shrink: 0;
+	height: 1px;
+}
+
+.pageLoader {
+	flex-shrink: 0;
+	padding: var(--spacing-4) var(--spacing-6);
+	border: 1px solid var(--l2-border);
+	border-radius: var(--radius-2);
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/ThreadSpanList.tsx

@@ -0,0 +1,55 @@
+import { ReactNode, RefObject } from 'react';
+
+import { useThreadInfiniteScroll } from './hooks/useThreadInfiniteScroll';
+import ThreadPageLoader from './ThreadPageLoader';
+
+import styles from './ThreadSpanList.module.scss';
+
+interface ThreadSpanListProps {
+	listRef: RefObject<HTMLDivElement>;
+	firstItemKey?: string;
+	hasNextPage: boolean;
+	hasPreviousPage: boolean;
+	isFetchingNextPage: boolean;
+	isFetchingPreviousPage: boolean;
+	fetchNextPage: () => Promise<unknown>;
+	fetchPreviousPage: () => Promise<unknown>;
+	children: ReactNode;
+}
+
+function ThreadSpanList({
+	listRef,
+	firstItemKey,
+	hasNextPage,
+	hasPreviousPage,
+	isFetchingNextPage,
+	isFetchingPreviousPage,
+	fetchNextPage,
+	fetchPreviousPage,
+	children,
+}: ThreadSpanListProps): JSX.Element {
+	const { topSentinelRef, bottomSentinelRef } = useThreadInfiniteScroll({
+		containerRef: listRef,
+		firstItemKey,
+		hasNextPage,
+		hasPreviousPage,
+		isFetchingNextPage,
+		isFetchingPreviousPage,
+		fetchNextPage,
+		fetchPreviousPage,
+	});
+
+	return (
+		<div className={styles.list} ref={listRef} data-testid="thread-span-list">
+			<div ref={topSentinelRef} className={styles.sentinel} />
+			{isFetchingPreviousPage && (
+				<ThreadPageLoader testId="thread-loading-previous" />
+			)}
+			{children}
+			{isFetchingNextPage && <ThreadPageLoader testId="thread-loading-next" />}
+			<div ref={bottomSentinelRef} className={styles.sentinel} />
+		</div>
+	);
+}
+
+export default ThreadSpanList;

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/ThreadSpanNotFound.tsx

@@ -0,0 +1,47 @@
+import { Button } from '@signozhq/ui/button';
+import { ArrowLeft, MessagesSquare, SearchX } from '@signozhq/icons';
+
+import ThreadEmptyState from './ThreadEmptyState';
+
+interface ThreadSpanNotFoundProps {
+	onGoBack: () => void;
+	onShowThread: () => void;
+}
+
+function ThreadSpanNotFound({
+	onGoBack,
+	onShowThread,
+}: ThreadSpanNotFoundProps): JSX.Element {
+	return (
+		<ThreadEmptyState
+			icon={<SearchX size={32} />}
+			title="Span not found in this thread"
+			description="The requested span isn't part of this trace's AI thread."
+			testId="thread-span-not-found"
+			actions={
+				<>
+					<Button
+						variant="outlined"
+						color="secondary"
+						prefix={<ArrowLeft size={14} />}
+						onClick={onGoBack}
+						testId="thread-span-not-found-go-back"
+					>
+						Go back
+					</Button>
+					<Button
+						variant="solid"
+						color="primary"
+						prefix={<MessagesSquare size={14} />}
+						onClick={onShowThread}
+						testId="thread-span-not-found-show-thread"
+					>
+						Show thread
+					</Button>
+				</>
+			}
+		/>
+	);
+}
+
+export default ThreadSpanNotFound;

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/ThreadViewToggle.tsx

@@ -0,0 +1,44 @@
+import { ToggleGroupSimple } from '@signozhq/ui/toggle-group';
+
+import { ThreadView } from './types';
+
+const VIEW_OPTIONS = [
+	{ label: 'Formatted', value: ThreadView.Formatted },
+	{ label: 'JSON', value: ThreadView.Json },
+];
+
+interface ThreadViewToggleProps {
+	value: ThreadView;
+	onChange: (view: ThreadView) => void;
+	testId?: string;
+}
+
+function ThreadViewToggle({
+	value,
+	onChange,
+	testId,
+}: ThreadViewToggleProps): JSX.Element {
+	const handleChange = (next: string): void => {
+		// Clicking the active item deselects it and reports ''.
+		if (next) {
+			onChange(next as ThreadView);
+		}
+	};
+
+	return (
+		<ToggleGroupSimple
+			type="single"
+			size="sm"
+			value={value}
+			onChange={handleChange}
+			items={VIEW_OPTIONS}
+			testId={testId}
+		/>
+	);
+}
+
+ThreadViewToggle.defaultProps = {
+	testId: 'thread-view-toggle',
+};
+
+export default ThreadViewToggle;

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

@@ -0,0 +1,50 @@
+.root {
+	flex: 1;
+	min-height: 0;
+	display: flex;
+	overflow: hidden;
+	border-top: 1px solid var(--l2-border);
+}
+
+.content {
+	flex: 1;
+	min-width: 0;
+	display: flex;
+	flex-direction: column;
+}
+
+.toolbar {
+	display: flex;
+	align-items: center;
+	justify-content: space-between;
+	gap: var(--spacing-4);
+	padding: var(--spacing-4) var(--spacing-8);
+	border-bottom: 1px solid var(--l2-border);
+	font-size: var(--font-size-xs);
+	color: var(--l2-foreground);
+}
+
+.notice {
+	margin: var(--spacing-6) var(--spacing-8) 0;
+}
+
+.initialLoader {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-6);
+	padding: var(--spacing-6) var(--spacing-8);
+}
+
+.bottomDock {
+	display: flex;
+	flex-direction: column;
+	min-height: 0;
+	border-top: 1px solid var(--l2-border);
+}
+
+.rightDock {
+	display: flex;
+	flex-direction: column;
+	min-width: 0;
+	border-left: 1px solid var(--l2-border);
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/TraceDetailsThread.tsx

@@ -0,0 +1,152 @@
+import { useMemo, useRef } from 'react';
+import { useParams } from 'react-router-dom';
+import { Callout } from '@signozhq/ui/callout';
+import { TraceDetailV3URLProps } from 'types/api/trace/getTraceV3';
+
+import { useToolCallLinks } from '../AIThreadMessage/useToolCallLinks';
+import { TraceDetailsTab } from '../constants';
+import { useSpanDetailVariant } from '../hooks/useSpanDetailVariant';
+import { useTraceDetailsTab } from '../hooks/useTraceDetailsTab';
+import { SpanDetailVariant } from '../SpanDetailsPanel/constants';
+import { useScrollToAnchorSpan } from './hooks/useScrollToAnchorSpan';
+import { useThreadSpanSelection } from './hooks/useThreadSpanSelection';
+import { useThreadView } from './hooks/useThreadView';
+import { useTraceThread } from './hooks/useTraceThread';
+import ThreadNoAiSpans from './ThreadNoAiSpans';
+import ThreadPageLoader from './ThreadPageLoader';
+import ThreadSpanCard from './ThreadSpanCard';
+import ThreadSpanDetails from './ThreadSpanDetails';
+import ThreadSpanList from './ThreadSpanList';
+import ThreadSpanNotFound from './ThreadSpanNotFound';
+import ThreadViewToggle from './ThreadViewToggle';
+import { AnchorStatus } from './types';
+import { buildToolCallIndex, getAnchorStatus } from './utils';
+
+import styles from './TraceDetailsThread.module.scss';
+
+const INITIAL_LOADER_COUNT = 3;
+
+function TraceDetailsThread(): JSX.Element {
+	const { id: traceId } = useParams<TraceDetailV3URLProps>();
+	const [, setTab] = useTraceDetailsTab();
+	const [view, setView] = useThreadView();
+	const { anchorSpanId, clearAnchor, selectedSpanId, selectSpan, panelState } =
+		useThreadSpanSelection();
+	const thread = useTraceThread(traceId || '', anchorSpanId);
+	const { spans, isLoading, isError } = thread;
+
+	const listRef = useRef<HTMLDivElement>(null);
+	const toolCallIds = useMemo(() => buildToolCallIndex(spans), [spans]);
+	const { isToolLinkEnabled, onToolLinkClick } = useToolCallLinks(
+		listRef,
+		toolCallIds,
+	);
+
+	const anchorStatus = getAnchorStatus(anchorSpanId, spans, isLoading);
+	useScrollToAnchorSpan(
+		listRef,
+		anchorSpanId,
+		anchorStatus === AnchorStatus.Found,
+	);
+
+	const selectedSpan = spans.find((span) => span.span_id === selectedSpanId);
+	const [spanDetailVariant, setSpanDetailVariant] = useSpanDetailVariant();
+	const isBottomDocked = spanDetailVariant === SpanDetailVariant.DOCKED;
+
+	const spanDetails = panelState.isOpen && selectedSpan && (
+		<ThreadSpanDetails
+			panelState={panelState}
+			span={selectedSpan}
+			variant={spanDetailVariant}
+			onVariantChange={setSpanDetailVariant}
+		/>
+	);
+	const hasNoThread =
+		!isLoading &&
+		anchorStatus !== AnchorStatus.NotFound &&
+		(isError || spans.length === 0);
+
+	const renderBody = (): JSX.Element => {
+		if (isLoading) {
+			return (
+				<div className={styles.initialLoader} data-testid="thread-loading">
+					{Array.from({ length: INITIAL_LOADER_COUNT }).map((_, i) => (
+						// eslint-disable-next-line react/no-array-index-key
+						<ThreadPageLoader key={i} testId="thread-loading-item" />
+					))}
+				</div>
+			);
+		}
+		if (anchorStatus === AnchorStatus.NotFound) {
+			return (
+				<ThreadSpanNotFound
+					onGoBack={(): void => {
+						void setTab(TraceDetailsTab.Overview);
+					}}
+					onShowThread={clearAnchor}
+				/>
+			);
+		}
+		if (hasNoThread) {
+			return <ThreadNoAiSpans />;
+		}
+		return (
+			<>
+				{anchorStatus === AnchorStatus.NoMessages && (
+					<Callout
+						type="info"
+						size="small"
+						className={styles.notice}
+						title="The requested span has no input or output messages. Showing the rest of the thread."
+						testId="thread-anchor-no-messages"
+					/>
+				)}
+				<ThreadSpanList
+					listRef={listRef}
+					firstItemKey={spans[0]?.span_id}
+					hasNextPage={thread.hasNextPage}
+					hasPreviousPage={thread.hasPreviousPage}
+					isFetchingNextPage={thread.isFetchingNextPage}
+					isFetchingPreviousPage={thread.isFetchingPreviousPage}
+					fetchNextPage={thread.fetchNextPage}
+					fetchPreviousPage={thread.fetchPreviousPage}
+				>
+					{spans.map((span) => (
+						<ThreadSpanCard
+							key={span.span_id}
+							span={span}
+							view={view}
+							isSelected={span.span_id === selectedSpanId}
+							onSelect={selectSpan}
+							isToolLinkEnabled={isToolLinkEnabled}
+							onToolLinkClick={onToolLinkClick}
+						/>
+					))}
+				</ThreadSpanList>
+			</>
+		);
+	};
+
+	return (
+		<div className={styles.root} data-testid="trace-details-thread">
+			<div className={styles.content}>
+				{!hasNoThread && (
+					<div className={styles.toolbar}>
+						<ThreadViewToggle
+							value={view}
+							onChange={(next): void => {
+								void setView(next);
+							}}
+						/>
+						{spans.length > 0 && <span>Showing {spans.length} spans</span>}
+					</div>
+				)}
+				{renderBody()}
+				{isBottomDocked && spanDetails}
+			</div>
+			{!isBottomDocked && spanDetails}
+		</div>
+	);
+}
+
+export default TraceDetailsThread;

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/hooks/useIntersectionSentinel.ts

@@ -0,0 +1,28 @@
+import { RefObject, useEffect } from 'react';
+
+const ROOT_MARGIN = '200px 0px';
+
+/** Calls `onVisible` while enabled and the sentinel is within reach of the container's viewport. */
+export function useIntersectionSentinel(
+	containerRef: RefObject<HTMLElement>,
+	sentinelRef: RefObject<HTMLElement>,
+	isEnabled: boolean,
+	onVisible: () => void,
+): void {
+	useEffect(() => {
+		const sentinel = sentinelRef.current;
+		if (!isEnabled || !sentinel) {
+			return undefined;
+		}
+		const observer = new IntersectionObserver(
+			(entries) => {
+				if (entries.some((entry) => entry.isIntersecting)) {
+					onVisible();
+				}
+			},
+			{ root: containerRef.current, rootMargin: ROOT_MARGIN },
+		);
+		observer.observe(sentinel);
+		return (): void => observer.disconnect();
+	}, [containerRef, sentinelRef, isEnabled, onVisible]);
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/hooks/useScrollToAnchorSpan.ts

@@ -0,0 +1,27 @@
+import { RefObject, useEffect, useRef } from 'react';
+
+/** Scrolls the anchor span's card into view once, after it first renders. */
+export function useScrollToAnchorSpan(
+	containerRef: RefObject<HTMLElement>,
+	anchorSpanId: string | undefined,
+	isAnchorLoaded: boolean,
+): void {
+	const scrolledForRef = useRef<string>();
+
+	useEffect(() => {
+		if (
+			!anchorSpanId ||
+			!isAnchorLoaded ||
+			scrolledForRef.current === anchorSpanId
+		) {
+			return;
+		}
+		const card = containerRef.current?.querySelector<HTMLElement>(
+			`[data-span-id="${CSS.escape(anchorSpanId)}"]`,
+		);
+		if (card) {
+			scrolledForRef.current = anchorSpanId;
+			card.scrollIntoView({ block: 'start' });
+		}
+	}, [containerRef, anchorSpanId, isAnchorLoaded]);
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/hooks/useThreadInfiniteScroll.ts

@@ -0,0 +1,70 @@
+import { RefObject, useLayoutEffect, useRef } from 'react';
+
+import { useIntersectionSentinel } from './useIntersectionSentinel';
+
+interface UseThreadInfiniteScrollOptions {
+	containerRef: RefObject<HTMLDivElement>;
+	firstItemKey?: string;
+	hasNextPage: boolean;
+	hasPreviousPage: boolean;
+	isFetchingNextPage: boolean;
+	isFetchingPreviousPage: boolean;
+	fetchNextPage: () => Promise<unknown>;
+	fetchPreviousPage: () => Promise<unknown>;
+}
+
+interface UseThreadInfiniteScrollResult {
+	topSentinelRef: RefObject<HTMLDivElement>;
+	bottomSentinelRef: RefObject<HTMLDivElement>;
+}
+
+/** Loads pages as either list edge nears view, holding position on prepend. */
+export function useThreadInfiniteScroll({
+	containerRef,
+	firstItemKey,
+	hasNextPage,
+	hasPreviousPage,
+	isFetchingNextPage,
+	isFetchingPreviousPage,
+	fetchNextPage,
+	fetchPreviousPage,
+}: UseThreadInfiniteScrollOptions): UseThreadInfiniteScrollResult {
+	const topSentinelRef = useRef<HTMLDivElement>(null);
+	const bottomSentinelRef = useRef<HTMLDivElement>(null);
+	const heightBeforePrependRef = useRef<number | null>(null);
+
+	const loadPreviousRef = useRef((): void => {});
+	loadPreviousRef.current = (): void => {
+		heightBeforePrependRef.current = containerRef.current?.scrollHeight ?? null;
+		void fetchPreviousPage();
+	};
+	// Stable wrapper so the observer isn't recreated on every render.
+	const stableLoadPrevious = useRef((): void =>
+		loadPreviousRef.current(),
+	).current;
+
+	useIntersectionSentinel(
+		containerRef,
+		bottomSentinelRef,
+		hasNextPage && !isFetchingNextPage,
+		fetchNextPage,
+	);
+	useIntersectionSentinel(
+		containerRef,
+		topSentinelRef,
+		hasPreviousPage && !isFetchingPreviousPage,
+		stableLoadPrevious,
+	);
+
+	useLayoutEffect(() => {
+		const container = containerRef.current;
+		const previousHeight = heightBeforePrependRef.current;
+		if (!container || previousHeight === null) {
+			return;
+		}
+		heightBeforePrependRef.current = null;
+		container.scrollTop += container.scrollHeight - previousHeight;
+	}, [containerRef, firstItemKey]);
+
+	return { topSentinelRef, bottomSentinelRef };
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/hooks/useThreadSpanSelection.ts

@@ -0,0 +1,74 @@
+import { useCallback, useMemo, useState } from 'react';
+import { useDetailsPanel } from 'components/DetailsPanel';
+import { DetailsPanelState } from 'components/DetailsPanel/types';
+import { useSafeNavigate } from 'hooks/useSafeNavigate';
+import useUrlQuery from 'hooks/useUrlQuery';
+import { getUnstableCurrentSearchParams } from 'utils/getUnstableCurrentSearchParams';
+
+import { ThreadSpan } from '../types';
+
+const SPAN_ID_PARAM = 'spanId';
+
+interface ThreadSpanSelection {
+	// The spanId the thread was opened with; it shapes the first page fetched.
+	anchorSpanId?: string;
+	clearAnchor: () => void;
+	selectedSpanId?: string;
+	selectSpan: (span: ThreadSpan) => void;
+	panelState: DetailsPanelState;
+}
+
+export function useThreadSpanSelection(): ThreadSpanSelection {
+	const urlQuery = useUrlQuery();
+	const { safeNavigate } = useSafeNavigate();
+	const selectedSpanId = urlQuery.get(SPAN_ID_PARAM) || undefined;
+	const [anchorSpanId, setAnchorSpanId] = useState(selectedSpanId);
+
+	const setSpanIdParam = useCallback(
+		(spanId?: string): void => {
+			const params = getUnstableCurrentSearchParams();
+			if (spanId) {
+				params.set(SPAN_ID_PARAM, spanId);
+			} else {
+				params.delete(SPAN_ID_PARAM);
+			}
+			safeNavigate({ search: params.toString() }, { replace: true });
+		},
+		[safeNavigate],
+	);
+
+	const handleClose = useCallback(
+		(): void => setSpanIdParam(undefined),
+		[setSpanIdParam],
+	);
+
+	const panelState = useDetailsPanel({
+		entityId: selectedSpanId,
+		onClose: handleClose,
+	});
+
+	const { open: openPanel } = panelState;
+	const selectSpan = useCallback(
+		(span: ThreadSpan): void => {
+			setSpanIdParam(span.span_id);
+			openPanel();
+		},
+		[setSpanIdParam, openPanel],
+	);
+
+	const clearAnchor = useCallback((): void => {
+		setAnchorSpanId(undefined);
+		setSpanIdParam(undefined);
+	}, [setSpanIdParam]);
+
+	return useMemo(
+		() => ({
+			anchorSpanId,
+			clearAnchor,
+			selectedSpanId,
+			selectSpan,
+			panelState,
+		}),
+		[anchorSpanId, clearAnchor, selectedSpanId, selectSpan, panelState],
+	);
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/hooks/useThreadView.ts

@@ -0,0 +1,12 @@
+import { parseAsStringEnum, useQueryState, UseQueryStateReturn } from 'nuqs';
+
+import { ThreadView } from '../types';
+
+export function useThreadView(): UseQueryStateReturn<ThreadView, ThreadView> {
+	return useQueryState(
+		'view',
+		parseAsStringEnum(Object.values(ThreadView)).withDefault(
+			ThreadView.Formatted,
+		),
+	);
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsThread/hooks/useTraceThread.ts

@@ -0,0 +1,82 @@
+import { useMemo } from 'react';
+import { useInfiniteQuery } from 'react-query';
+import {
+	getGetTraceThreadQueryKey,
+	getTraceThread,
+} from 'api/generated/services/tracedetail';
+import type { GetTraceThreadParams } from 'api/generated/services/sigNoz.schemas';
+
+import { ThreadSpan } from '../types';
+import { isNotFoundError, toThreadSpan } from '../utils';
+
+const THREAD_PAGE_LIMIT = 100;
+const MAX_RETRIES = 3;
+
+type PageParam = Pick<GetTraceThreadParams, 'after' | 'before'>;
+
+interface UseTraceThreadResult {
+	spans: ThreadSpan[];
+	isLoading: boolean;
+	isError: boolean;
+	hasNextPage: boolean;
+	hasPreviousPage: boolean;
+	isFetchingNextPage: boolean;
+	isFetchingPreviousPage: boolean;
+	fetchNextPage: () => Promise<unknown>;
+	fetchPreviousPage: () => Promise<unknown>;
+}
+
+export function useTraceThread(
+	traceId: string,
+	anchorSpanId?: string,
+): UseTraceThreadResult {
+	const query = useInfiniteQuery({
+		queryKey: getGetTraceThreadQueryKey(
+			{ traceID: traceId },
+			{ spanId: anchorSpanId },
+		),
+		queryFn: ({ pageParam, signal }) => {
+			const { after, before } = (pageParam ?? {}) as PageParam;
+			return getTraceThread(
+				{ traceID: traceId },
+				{
+					limit: THREAD_PAGE_LIMIT,
+					after,
+					before,
+					// The anchor only shapes the first page; cursors drive the rest.
+					spanId: after || before ? undefined : anchorSpanId,
+				},
+				signal,
+			);
+		},
+		getNextPageParam: (lastPage): PageParam | undefined =>
+			lastPage.data.nextCursor ? { after: lastPage.data.nextCursor } : undefined,
+		getPreviousPageParam: (firstPage): PageParam | undefined =>
+			firstPage.data.prevCursor
+				? { before: firstPage.data.prevCursor }
+				: undefined,
+		// An unknown anchor span is a 404; retrying won't find it.
+		retry: (failureCount, error): boolean =>
+			!isNotFoundError(error) && failureCount < MAX_RETRIES,
+		enabled: !!traceId,
+		refetchOnWindowFocus: false,
+	});
+
+	const spans = useMemo(
+		() =>
+			query.data?.pages.flatMap((page) => page.data.spans.map(toThreadSpan)) ?? [],
+		[query.data],
+	);
+
+	return {
+		spans,
+		isLoading: query.isLoading,
+		isError: query.isError,
+		hasNextPage: !!query.hasNextPage,
+		hasPreviousPage: !!query.hasPreviousPage,
+		isFetchingNextPage: query.isFetchingNextPage,
+		isFetchingPreviousPage: query.isFetchingPreviousPage,
+		fetchNextPage: query.fetchNextPage,
+		fetchPreviousPage: query.fetchPreviousPage,
+	};
+}

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

@@ -0,0 +1,55 @@
+import { SpanV3 } from 'types/api/trace/getTraceV3';
+
+export type MessagePart =
+	| { type: 'text'; content: string }
+	| { type: 'thinking'; content?: string }
+	| {
+			type: 'tool_call';
+			id: string;
+			name: string;
+			arguments: unknown;
+			server?: boolean;
+	  }
+	| {
+			type: 'tool_result';
+			toolCallId: string;
+			name?: string;
+			content: string;
+			isError?: boolean;
+	  }
+	| {
+			type: 'media';
+			modality?: string;
+			mimeType?: string;
+			uri?: string;
+			name?: string;
+			sizeBytes?: number;
+	  }
+	| { type: 'generic'; content: string };
+
+export interface ThreadMessage {
+	// system | user | assistant | tool; any other value renders headerless.
+	role?: string;
+	content: MessagePart[];
+	// stop | tool_call | length | content_filter | error, or provider-specific.
+	finishReason?: string;
+}
+
+export type ThreadSpan = SpanV3 & {
+	formatted_input?: ThreadMessage[];
+	formatted_output?: ThreadMessage[];
+};
+
+export enum ThreadView {
+	Formatted = 'formatted',
+	Json = 'json',
+}
+
+export enum AnchorStatus {
+	None = 'none',
+	Loading = 'loading',
+	Found = 'found',
+	// Backend anchors on the span's position but drops it for lacking messages.
+	NoMessages = 'noMessages',
+	NotFound = 'notFound',
+}

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

@@ -0,0 +1,51 @@
+import type { SpantypesThreadSpanDTO } from 'api/generated/services/sigNoz.schemas';
+import { isAxiosError } from 'axios';
+
+import { collectToolCallIds } from '../AIThreadMessage/utils';
+import { AnchorStatus, ThreadSpan } from './types';
+
+type WireThreadSpan = Omit<ThreadSpan, 'timestamp' | 'service.name'> & {
+	time_unix: number;
+};
+
+/** Derives SpanV3's `timestamp` and `service.name`, as the waterfall does. */
+export function toThreadSpan(span: SpantypesThreadSpanDTO): ThreadSpan {
+	const wire = span as unknown as WireThreadSpan;
+	return {
+		...wire,
+		'service.name': wire.resource?.['service.name'] || '',
+		timestamp: wire.time_unix,
+	};
+}
+
+export function isNotFoundError(error: unknown): boolean {
+	return isAxiosError(error) && error.response?.status === 404;
+}
+
+export function buildToolCallIndex(spans: ThreadSpan[]): Set<string> {
+	return new Set(
+		spans.flatMap((span) => [
+			...collectToolCallIds(span.formatted_input ?? []),
+			...collectToolCallIds(span.formatted_output ?? []),
+		]),
+	);
+}
+
+export function getAnchorStatus(
+	anchorSpanId: string | undefined,
+	spans: ThreadSpan[],
+	isLoading: boolean,
+): AnchorStatus {
+	if (!anchorSpanId) {
+		return AnchorStatus.None;
+	}
+	if (isLoading) {
+		return AnchorStatus.Loading;
+	}
+	if (spans.length === 0) {
+		return AnchorStatus.NotFound;
+	}
+	return spans.some((span) => span.span_id === anchorSpanId)
+		? AnchorStatus.Found
+		: AnchorStatus.NoMessages;
+}

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

@@ -0,0 +1,6 @@
+.root {
+	flex: 1;
+	min-height: 0;
+	display: flex;
+	flex-direction: column;
+}

frontend/src/pages/TraceDetailsV3/TraceDetailsWrapper/TraceDetailsWrapper.tsx

@@ -0,0 +1,21 @@
+import { ReactNode } from 'react';
+
+import TraceStoreSync from '../stores/TraceStoreSync';
+
+import styles from './TraceDetailsWrapper.module.scss';
+
+interface TraceDetailsWrapperProps {
+	children: ReactNode;
+}
+
+function TraceDetailsWrapper({
+	children,
+}: TraceDetailsWrapperProps): JSX.Element {
+	return (
+		<TraceStoreSync>
+			<div className={styles.root}>{children}</div>
+		</TraceStoreSync>
+	);
+}
+
+export default TraceDetailsWrapper;

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

@@ -30,13 +30,9 @@
 // lives here. Shares visual treatment with the waterfall hover popover
 // but is positioned `fixed` instead of anchored.
 .tooltip {
+	composes: tooltipSurface from '../shared.module.scss';
 	position: fixed;
 	z-index: 1000;
 	pointer-events: none;
-	background-color: var(--l1-background);
-	padding: 8px 12px;
-	border-radius: 4px;
-	box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
-	border: 1px solid var(--l2-border);
 	color: var(--l1-foreground);
 }

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

@@ -1,8 +1,9 @@
 import { useCallback, useEffect, useMemo, useState } from 'react';
-import { useHistory, useLocation, useParams } from 'react-router-dom';
+import { useHistory, useParams } from 'react-router-dom';
 import { Skeleton } from 'antd';
 import useGetTraceFlamegraphV3 from 'hooks/trace/useGetTraceFlamegraphV3';
 import useUrlQuery from 'hooks/useUrlQuery';
+import { getUnstableCurrentSearchParams } from 'utils/getUnstableCurrentSearchParams';
 import { TraceDetailFlamegraphURLProps } from 'types/api/trace/getTraceFlamegraph';
 import { SpanV3 } from 'types/api/trace/getTraceV3';
 
@@ -30,7 +31,6 @@ function TraceFlamegraph({
 	const { id: traceId } = useParams<TraceDetailFlamegraphURLProps>();
 	const urlQuery = useUrlQuery();
 	const history = useHistory();
-	const { search } = useLocation();
 	const [firstSpanAtFetchLevel, setFirstSpanAtFetchLevel] = useState<string>(
 		urlQuery.get('spanId') || '',
 	);
@@ -42,14 +42,14 @@ function TraceFlamegraph({
 	const handleSpanClick = useCallback(
 		(spanId: string): void => {
 			setFirstSpanAtFetchLevel(spanId);
-			const searchParams = new URLSearchParams(search);
+			const searchParams = getUnstableCurrentSearchParams();
 			//tood: use from query params constants
 			if (searchParams.get('spanId') !== spanId) {
 				searchParams.set('spanId', spanId);
 				history.replace({ search: searchParams.toString() });
 			}
 		},
-		[history, search],
+		[history],
 	);
 
 	const previewFields = useTraceStore((s) => s.previewFields);

frontend/src/pages/TraceDetailsV3/TraceTooltip/TokenBreakdown.tsx

@@ -0,0 +1,59 @@
+import { formatTokens } from '../utils/genAi';
+import TooltipRow from './TooltipRow';
+import TooltipSection from './TooltipSection';
+
+interface TokenBreakdownProps {
+	input?: number;
+	output?: number;
+	cacheRead?: number;
+	cacheWrite?: number;
+}
+
+function TokenBreakdown({
+	input,
+	output,
+	cacheRead,
+	cacheWrite,
+}: TokenBreakdownProps): JSX.Element {
+	const showCacheRead = !!cacheRead;
+	const showCacheWrite = !!cacheWrite;
+
+	return (
+		<>
+			{input !== undefined && (
+				<TooltipSection>
+					<TooltipRow label="Input" value={formatTokens(input)} isHeading />
+				</TooltipSection>
+			)}
+			{(showCacheRead || showCacheWrite) && (
+				<TooltipSection>
+					<TooltipRow label="Cache" isHeading />
+					{showCacheRead && (
+						<TooltipRow label="Cache read" value={formatTokens(cacheRead)} isNested />
+					)}
+					{showCacheWrite && (
+						<TooltipRow
+							label="Cache write"
+							value={formatTokens(cacheWrite)}
+							isNested
+						/>
+					)}
+				</TooltipSection>
+			)}
+			{output !== undefined && (
+				<TooltipSection>
+					<TooltipRow label="Output" value={formatTokens(output)} isHeading />
+				</TooltipSection>
+			)}
+		</>
+	);
+}
+
+TokenBreakdown.defaultProps = {
+	input: undefined,
+	output: undefined,
+	cacheRead: undefined,
+	cacheWrite: undefined,
+};
+
+export default TokenBreakdown;

frontend/src/pages/TraceDetailsV3/TraceTooltip/TooltipRow.tsx

@@ -0,0 +1,42 @@
+import { Typography } from '@signozhq/ui/typography';
+import cx from 'classnames';
+
+import styles from './TraceTooltip.module.scss';
+
+interface TooltipRowProps {
+	label: string;
+	value?: string;
+	isNested?: boolean;
+	isHeading?: boolean;
+	testId?: string;
+}
+
+function TooltipRow({
+	label,
+	value,
+	isNested,
+	isHeading,
+	testId,
+}: TooltipRowProps): JSX.Element {
+	return (
+		<div
+			className={cx(styles.row, isNested && styles.nestedRow)}
+			data-testid={testId}
+		>
+			<Typography.Text
+				size="small"
+				color={isHeading ? undefined : 'muted'}
+				truncate={1}
+			>
+				{label}
+			</Typography.Text>
+			{value !== undefined && (
+				<Typography.Text size="small" truncate={1} className={styles.rowValue}>
+					{value}
+				</Typography.Text>
+			)}
+		</div>
+	);
+}
+
+export default TooltipRow;

frontend/src/pages/TraceDetailsV3/TraceTooltip/TooltipSection.tsx

@@ -0,0 +1,13 @@
+import { ReactNode } from 'react';
+
+import styles from './TraceTooltip.module.scss';
+
+interface TooltipSectionProps {
+	children: ReactNode;
+}
+
+function TooltipSection({ children }: TooltipSectionProps): JSX.Element {
+	return <div className={styles.section}>{children}</div>;
+}
+
+export default TooltipSection;

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

@@ -0,0 +1,41 @@
+.section {
+	display: flex;
+	flex-direction: column;
+	gap: var(--spacing-2);
+	padding: var(--spacing-2) 0;
+	border-top: 1px solid;
+	border-image: linear-gradient(
+			90deg,
+			var(--l3-background-transparent),
+			var(--l3-border),
+			var(--l3-background-transparent)
+		)
+		1;
+
+	&:first-child {
+		padding-top: 0;
+		border-top: none;
+	}
+
+	&:last-child {
+		padding-bottom: 0;
+	}
+}
+
+.row {
+	display: flex;
+	justify-content: space-between;
+	gap: var(--spacing-2);
+	min-width: 0;
+}
+
+.nestedRow {
+	padding-left: var(--spacing-6);
+}
+
+.rowValue {
+	flex-shrink: 0;
+	max-width: 60%;
+	text-align: right;
+	font-variant-numeric: tabular-nums;
+}

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

@@ -1,5 +1,5 @@
 import { useCallback, useRef, useState } from 'react';
-import { useHistory, useLocation } from 'react-router-dom';
+import { useHistory } from 'react-router-dom';
 import { ArrowRightFromLine, Search, X } from '@signozhq/icons';
 import { Switch } from '@signozhq/ui/switch';
 import { ToggleGroupSimple } from '@signozhq/ui/toggle-group';
@@ -18,6 +18,7 @@ import { DEFAULT_ENTITY_VERSION } from 'constants/app';
 import { initialQueriesMap, PANEL_TYPES } from 'constants/queryBuilder';
 import { useGetQueryRange } from 'hooks/queryBuilder/useGetQueryRange';
 import { uniqBy } from 'lodash-es';
+import { getUnstableCurrentSearchParams } from 'utils/getUnstableCurrentSearchParams';
 import NozButton from 'pages/TraceDetailsV3/TraceDetailsHeader/NozButton';
 import CopyButton from 'periscope/components/CopyButton/CopyButton';
 import { DataTypes } from 'types/api/queryBuilder/queryAutocompleteResponse';
@@ -179,12 +180,11 @@ function Filters({
 	const { selectedCategory, categories, handleCategoryChange } =
 		useSpanCategoryFilter(filterProps);
 
-	const { search } = useLocation();
 	const history = useHistory();
 
 	const handlePrevNext = useCallback(
 		(index: number, spanId?: string): void => {
-			const searchParams = new URLSearchParams(search);
+			const searchParams = getUnstableCurrentSearchParams();
 			if (spanId) {
 				searchParams.set('spanId', spanId);
 			} else {
@@ -193,7 +193,7 @@ function Filters({
 
 			history.replace({ search: searchParams.toString() });
 		},
-		[filteredSpanIds, history, search],
+		[filteredSpanIds, history],
 	);
 
 	const { isFetching, error } = useGetQueryRange(

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

@@ -217,8 +217,9 @@
 .statusCell {
 	display: flex;
 	align-items: center;
-	justify-content: center;
+	justify-content: flex-start;
 	cursor: pointer;
+	padding-left: var(--spacing-2);
 
 	--badge-border-radius: 2px;
 	--badge-padding: 3px 6px;
@@ -408,6 +409,11 @@
 	}
 }
 
+.aiSpanIcon {
+	flex-shrink: 0;
+	margin: 0 var(--spacing-2);
+}
+
 .treeLabel {
 	color: var(--l1-foreground);
 	font-family: 'Inter';

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

@@ -25,15 +25,20 @@ import {
 } from '@tanstack/react-table';
 import { useVirtualizer, Virtualizer } from '@tanstack/react-virtual';
 import cx from 'classnames';
-import HttpStatusBadge from 'components/HttpStatusBadge/HttpStatusBadge';
 import TimelineV3 from 'components/TimelineV3/TimelineV3';
 import { convertTimeToRelevantUnit } from 'utils/traceUtils';
 import { useCopySpanLink } from 'hooks/trace/useCopySpanLink';
 import { useIsDarkMode } from 'hooks/useDarkMode';
 import { useSafeNavigate } from 'hooks/useSafeNavigate';
-import useUrlQuery from 'hooks/useUrlQuery';
+import { getUnstableCurrentSearchParams } from 'utils/getUnstableCurrentSearchParams';
 import { colorToRgb } from 'lib/uPlotLib/utils/generateColor';
-import { ChevronDown, ChevronRight, Link, ListPlus } from '@signozhq/icons';
+import {
+	ChevronDown,
+	ChevronRight,
+	Link,
+	ListPlus,
+	Sparkle,
+} from '@signozhq/icons';
 import { useTraceStore } from 'pages/TraceDetailsV3/stores/traceStore';
 import { resolveSpanColor } from 'pages/TraceDetailsV3/utils';
 import { useBoundaryPagination } from 'pages/TraceDetailsV3/TraceWaterfall/hooks/useBoundaryPagination';
@@ -44,6 +49,8 @@ import { toFixed } from 'utils/toFixed';
 
 import { EventTooltipContent } from '../../../SpanHoverCard/EventTooltipContent';
 import { SpanHoverCard } from '../../../SpanHoverCard/SpanHoverCard';
+import SpanHintBadge from '../../../SpanHintBadge/SpanHintBadge';
+import { isAiSpan } from '../../../utils/genAi';
 import AddSpanToFunnelModal from '../../AddSpanToFunnelModal/AddSpanToFunnelModal';
 import { IInterestedSpan } from '../../types';
 
@@ -328,14 +335,23 @@ const SpanOverview = memo(function SpanOverview({
 			</span>
 
 			{/* Colored service dot */}
-			<span
-				className={cx(styles.treeIcon, { [styles.hasError]: span.has_error })}
-				style={
-					{
-						'--service-dot-color': effectiveColor,
-					} as React.CSSProperties
-				}
-			/>
+			{isAiSpan(span) ? (
+				<Sparkle
+					size={10}
+					color={effectiveColor}
+					fill={effectiveColor}
+					className={styles.aiSpanIcon}
+				/>
+			) : (
+				<span
+					className={cx(styles.treeIcon, { [styles.hasError]: span.has_error })}
+					style={
+						{
+							'--service-dot-color': effectiveColor,
+						} as React.CSSProperties
+					}
+				/>
+			)}
 
 			{/* Span name + service name */}
 			<span className={styles.treeLabel}>
@@ -680,19 +696,19 @@ function Success(props: ISuccessProps): JSX.Element {
 		setSelectedSpanToAddToFunnel(span);
 	}, []);
 
-	const urlQuery = useUrlQuery();
 	const { safeNavigate } = useSafeNavigate();
 
 	const handleSpanClick = useCallback(
 		(span: SpanV3): void => {
 			setSelectedSpan(span);
+			const params = getUnstableCurrentSearchParams();
 			if (span?.span_id) {
-				urlQuery.set('spanId', span?.span_id);
+				params.set('spanId', span?.span_id);
 			}
 
-			safeNavigate({ search: urlQuery.toString() }, { replace: true });
+			safeNavigate({ search: params.toString() }, { replace: true });
 		},
-		[setSelectedSpan, urlQuery, safeNavigate],
+		[setSelectedSpan, safeNavigate],
 	);
 
 	// Left side columns using TanStack React Table (extensible for future columns)
@@ -971,9 +987,7 @@ function Success(props: ISuccessProps): JSX.Element {
 									onMouseLeave={(): void => applyHoverClass(null)}
 									onClick={(): void => handleSpanClick(span)}
 								>
-									{span.response_status_code && (
-										<HttpStatusBadge statusCode={span.response_status_code} />
-									)}
+									<SpanHintBadge span={span} />
 								</div>
 							);
 						})}

frontend/src/pages/TraceDetailsV3/TraceWaterfall/TraceWaterfallStates/Success/__tests__/UnifiedSpanClick.test.tsx

@@ -1,6 +1,10 @@
 import React from 'react';
 import { render, screen, userEvent, waitFor } from 'tests/test-utils';
 import { SpanV3 } from 'types/api/trace/getTraceV3';
+import {
+	__resetSearchParamsGetter,
+	__setSearchParamsGetterForTest,
+} from 'utils/getUnstableCurrentSearchParams';
 
 // Local identity-proxy mock for this module so `styles.foo` resolves to
 // `'foo'` in test assertions. The global `__mocks__/cssMock.ts` stays as
@@ -226,6 +230,11 @@ describe('Span Click User Flows', () => {
 		jest.clearAllMocks();
 		// Clear all URL parameters
 		Array.from(mockUrlQuery.keys()).forEach((key) => mockUrlQuery.delete(key));
+		__setSearchParamsGetterForTest(() => new URLSearchParams(mockUrlQuery));
+	});
+
+	afterEach(() => {
+		__resetSearchParamsGetter();
 	});
 
 	it('clicking span updates URL with spanId parameter', async () => {
@@ -260,7 +269,6 @@ describe('Span Click User Flows', () => {
 		) as HTMLElement;
 		await user.click(spanElement);
 
-		expect(mockUrlQuery.get('spanId')).toBe('span-1');
 		expect(mockSafeNavigate).toHaveBeenCalledWith(
 			{
 				search: expect.stringContaining('spanId=span-1'),
@@ -428,10 +436,6 @@ describe('Span Click User Flows', () => {
 		await user.click(spanElement);
 
 		// Verify existing parameters are preserved and spanId is added
-		expect(mockUrlQuery.get('existingParam')).toBe('existingValue');
-		expect(mockUrlQuery.get('anotherParam')).toBe('anotherValue');
-		expect(mockUrlQuery.get('spanId')).toBe('span-1');
-
 		expect(mockSafeNavigate).toHaveBeenCalledWith(
 			{
 				search: expect.stringMatching(

frontend/src/pages/TraceDetailsV3/constants.ts

@@ -53,3 +53,11 @@ export const COLOR_BY_FIELDS: TelemetryFieldKey[] = COLOR_BY_OPTIONS.map(
 );
 
 export const DEFAULT_COLOR_BY_FIELD = COLOR_BY_FIELDS[0];
+
+export enum TraceDetailsTab {
+	Overview = 'overview',
+	Thread = 'thread',
+}
+
+export const LLM_OBSERVABILITY_DOCS_URL =
+	'https://signoz.io/docs/llm-observability/';

frontend/src/pages/TraceDetailsV3/hooks/useSpanDetailVariant.ts

@@ -0,0 +1,26 @@
+import { useCallback, useState } from 'react';
+import getLocalStorageKey from 'api/browser/localstorage/get';
+import setLocalStorageKey from 'api/browser/localstorage/set';
+import { LOCALSTORAGE } from 'constants/localStorage';
+
+import { SpanDetailVariant } from '../SpanDetailsPanel/constants';
+
+/** Span details position, persisted under the same key Overview uses. */
+export function useSpanDetailVariant(): [
+	SpanDetailVariant,
+	(variant: SpanDetailVariant) => void,
+] {
+	const [variant, setVariant] = useState<SpanDetailVariant>(
+		() =>
+			(getLocalStorageKey(
+				LOCALSTORAGE.TRACE_DETAILS_SPAN_DETAILS_POSITION,
+			) as SpanDetailVariant) || SpanDetailVariant.DOCKED_RIGHT,
+	);
+
+	const changeVariant = useCallback((next: SpanDetailVariant): void => {
+		setLocalStorageKey(LOCALSTORAGE.TRACE_DETAILS_SPAN_DETAILS_POSITION, next);
+		setVariant(next);
+	}, []);
+
+	return [variant, changeVariant];
+}

frontend/src/pages/TraceDetailsV3/hooks/useTraceDetailsTab.ts

@@ -0,0 +1,15 @@
+import { parseAsStringEnum, useQueryState, UseQueryStateReturn } from 'nuqs';
+
+import { TraceDetailsTab } from '../constants';
+
+export function useTraceDetailsTab(): UseQueryStateReturn<
+	TraceDetailsTab,
+	TraceDetailsTab
+> {
+	return useQueryState(
+		'tab',
+		parseAsStringEnum(Object.values(TraceDetailsTab)).withDefault(
+			TraceDetailsTab.Overview,
+		),
+	);
+}

frontend/src/pages/TraceDetailsV3/index.tsx

@@ -1,87 +1,18 @@
-/* eslint-disable sonarjs/cognitive-complexity */
-import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
-import { useParams } from 'react-router-dom';
-import {
-	ChartNoAxesGantt,
-	ChevronDown,
-	ChevronRight,
-	Info,
-	TriangleAlert,
-} from '@signozhq/icons';
-import getLocalStorageKey from 'api/browser/localstorage/get';
-import setLocalStorageKey from 'api/browser/localstorage/set';
-import { Collapse } from 'antd';
-import { useDetailsPanel } from 'components/DetailsPanel';
-import WarningPopover from 'components/WarningPopover/WarningPopover';
-import { LOCALSTORAGE } from 'constants/localStorage';
-import useGetTraceV4 from 'hooks/trace/useGetTraceV4';
-import { useTraceDetailsStripInfo } from './useTraceDetailsStripInfo';
-import { useSafeNavigate } from 'hooks/useSafeNavigate';
-import useUrlQuery from 'hooks/useUrlQuery';
-import { ResizableBox } from 'periscope/components/ResizableBox';
-import { SpanV3, TraceDetailV3URLProps } from 'types/api/trace/getTraceV3';
+import { useCallback, useEffect, useState } from 'react';
 
-import { TraceDetailEventKeys, TraceDetailEvents } from './events';
-import { useTraceDetailLogEvent } from './hooks/useTraceDetailLogEvent';
-import NoData from './NoData/NoData';
-import TraceStoreSync from './stores/TraceStoreSync';
-import { useTraceStore } from './stores/traceStore';
-import { SpanDetailVariant } from './SpanDetailsPanel/constants';
-import SpanDetailsPanel from './SpanDetailsPanel/SpanDetailsPanel';
+import { TraceDetailsTab } from './constants';
+import { useTraceDetailsTab } from './hooks/useTraceDetailsTab';
 import TraceDetailsHeader from './TraceDetailsHeader/TraceDetailsHeader';
-import { FLAMEGRAPH_SPAN_LIMIT } from './TraceFlamegraph/constants';
-import TraceFlamegraph from './TraceFlamegraph/TraceFlamegraph';
-import TraceWaterfall from './TraceWaterfall/TraceWaterfall';
-import { IInterestedSpan } from './TraceWaterfall/types';
-import { getAncestorSpanIds } from './TraceWaterfall/utils';
-import { getAvailableColorByFieldNames } from './utils';
-
-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} />;
-}
+import TraceDetailsOverview from './TraceDetailsOverview/TraceDetailsOverview';
+import TraceDetailsThread from './TraceDetailsThread/TraceDetailsThread';
+import TraceDetailsWrapper from './TraceDetailsWrapper/TraceDetailsWrapper';
 
 function TraceDetailsV3(): JSX.Element {
-	const { id: traceId } = useParams<TraceDetailV3URLProps>();
-	const urlQuery = useUrlQuery();
-	const [interestedSpanId, setInterestedSpanId] = useState<IInterestedSpan>(
-		() => ({
-			spanId: urlQuery.get('spanId') || '',
-			isUncollapsed: urlQuery.get('spanId') !== '',
-		}),
-	);
-	const [uncollapsedNodes, setUncollapsedNodes] = useState<string[]>([]);
-	const [localUncollapsedNodes, setLocalUncollapsedNodes] = useState<
-		Set<string>
-	>(new Set());
-	const [selectedSpan, setSelectedSpan] = useState<SpanV3>();
+	const [tab] = useTraceDetailsTab();
+	const isOverview = tab === TraceDetailsTab.Overview;
 	const [filteredSpanIds, setFilteredSpanIds] = useState<string[]>([]);
 	const [isFilterActive, setIsFilterActive] = useState(false);
-
-	const selectedSpanId = urlQuery.get('spanId') || undefined;
-	const { safeNavigate } = useSafeNavigate();
-
-	const logTraceEvent = useTraceDetailLogEvent('v3', traceId || '');
-	// Tracks which traceId the load event already fired for, so navigating
-	// between traces (the route component stays mounted) re-fires it once each.
-	const dataLoadedFiredForRef = useRef('');
-	const colorByField = useTraceStore((s) => s.colorByField);
-	const previewFieldsCount = useTraceStore((s) => s.previewFields.length);
-	const userPrefsReady = useTraceStore((s) => s.userPreferences !== null);
-
-	const handleSpanDetailsClose = useCallback((): void => {
-		urlQuery.delete('spanId');
-		safeNavigate({ search: urlQuery.toString() }, { replace: true });
-	}, [urlQuery, safeNavigate]);
+	const [hasTraceData, setHasTraceData] = useState(false);
 
 	const handleFilteredSpansChange = useCallback(
 		(spanIds: string[], isActive: boolean): void => {
@@ -91,421 +22,30 @@ function TraceDetailsV3(): JSX.Element {
 		[],
 	);
 
-	const panelState = useDetailsPanel({
-		entityId: selectedSpanId,
-		onClose: handleSpanDetailsClose,
-	});
-
-	const allSpansRef = useRef<SpanV3[]>([]);
-	const deepLinkResolvedRef = useRef(false);
-
-	// Refetch only when the URL target isn't already loaded. Keeps row clicks
-	// and other in-window URL navigation from triggering a backend window slide.
+	// The filter query lives in Filters' local state, which unmounts with the
+	// Overview tab; drop its result too so both start empty on return.
 	useEffect(() => {
-		const spanId = urlQuery.get('spanId') || '';
-		if (!spanId) {
-			return;
+		if (!isOverview) {
+			handleFilteredSpansChange([], false);
 		}
-		const idx = allSpansRef.current.findIndex((s) => s.span_id === spanId);
-		if (idx !== -1) {
-			setSelectedSpan(allSpansRef.current[idx]);
-			return;
-		}
-		setInterestedSpanId({ spanId, isUncollapsed: true });
-	}, [urlQuery]);
-
-	// Once all spans are loaded (frontend mode), freeze query params so
-	// subsequent interestedSpanId changes don't trigger unnecessary refetches.
-	const fullDataLoadedRef = useRef(false);
-	const frozenParamsRef = useRef({
-		selectedSpanId: interestedSpanId.spanId,
-		isSelectedSpanIDUnCollapsed: interestedSpanId.isUncollapsed,
-		uncollapsedSpans: uncollapsedNodes,
-	});
-
-	const queryParams = fullDataLoadedRef.current
-		? frozenParamsRef.current
-		: {
-				selectedSpanId: interestedSpanId.spanId,
-				isSelectedSpanIDUnCollapsed: interestedSpanId.isUncollapsed,
-				uncollapsedSpans: uncollapsedNodes,
-			};
-
-	const {
-		data: traceData,
-		isFetching: isFetchingTraceData,
-		error: errorFetchingTraceData,
-	} = useGetTraceV4({
-		traceId,
-		uncollapsedSpans: queryParams.uncollapsedSpans,
-		selectedSpanId: queryParams.selectedSpanId,
-		isSelectedSpanIDUnCollapsed: queryParams.isSelectedSpanIDUnCollapsed,
-	});
-
-	const allSpans = traceData?.payload?.spans || [];
-	const totalSpansCount = traceData?.payload?.totalSpansCount || 0;
-	const totalErrorSpansCount = traceData?.payload?.totalErrorSpansCount || 0;
-
-	useTraceDetailsStripInfo({ totalSpansCount, totalErrorSpansCount });
-
-	const isFullDataLoaded =
-		totalSpansCount > 0 && totalSpansCount <= allSpans.length;
-
-	// Color-by options, gated on fields in loaded spans. Resource attrs are
-	// trace-wide, so any window has the full set — no need to accumulate.
-	const availableColorByFields = useMemo(() => {
-		const spans = traceData?.payload?.spans;
-		return spans?.length ? getAvailableColorByFieldNames(spans) : undefined;
-	}, [traceData?.payload?.spans]);
-
-	// Lock the ref once we confirm all data is loaded
-	if (isFullDataLoaded && !fullDataLoadedRef.current) {
-		fullDataLoadedRef.current = true;
-		frozenParamsRef.current = {
-			selectedSpanId: interestedSpanId.spanId,
-			isSelectedSpanIDUnCollapsed: interestedSpanId.isUncollapsed,
-			uncollapsedSpans: uncollapsedNodes,
-		};
-	}
-
-	useEffect(() => {
-		allSpansRef.current = allSpans;
-	}, [allSpans]);
-
-	useEffect(() => {
-		if (
-			!traceId ||
-			dataLoadedFiredForRef.current === traceId ||
-			!userPrefsReady
-		) {
-			return;
-		}
-		const payload = traceData?.payload;
-		if (!payload?.spans?.length) {
-			return;
-		}
-		dataLoadedFiredForRef.current = traceId;
-		const numServices = new Set(payload.spans.map((s) => s['service.name'])).size;
-		logTraceEvent(TraceDetailEvents.DataLoaded, {
-			[TraceDetailEventKeys.TotalSpansCount]: totalSpansCount,
-			[TraceDetailEventKeys.NumServices]: numServices,
-			[TraceDetailEventKeys.TraceDurationMs]:
-				payload.endTimestampMillis - payload.startTimestampMillis,
-			[TraceDetailEventKeys.HadErrors]: (payload.totalErrorSpansCount || 0) > 0,
-			[TraceDetailEventKeys.FlamegraphSampled]:
-				totalSpansCount > FLAMEGRAPH_SPAN_LIMIT,
-			[TraceDetailEventKeys.SpanPanelVariant]:
-				getLocalStorageKey(LOCALSTORAGE.TRACE_DETAILS_SPAN_DETAILS_POSITION) ||
-				SpanDetailVariant.DOCKED_RIGHT,
-			[TraceDetailEventKeys.ColorByField]: colorByField.name,
-			[TraceDetailEventKeys.PreviewFieldsCount]: previewFieldsCount,
-		});
-	}, [
-		traceId,
-		userPrefsReady,
-		traceData,
-		totalSpansCount,
-		colorByField,
-		previewFieldsCount,
-		logTraceEvent,
-	]);
-
-	// Frontend mode: expand all parents by default when full data arrives
-	useEffect(() => {
-		if (isFullDataLoaded && allSpans.length > 0) {
-			const parentIds = new Set(
-				allSpans.filter((s) => s.has_children).map((s) => s.span_id),
-			);
-			setLocalUncollapsedNodes(parentIds);
-		}
-	}, [isFullDataLoaded, allSpans]);
-
-	// Backend mode: sync uncollapsed state from API response
-	useEffect(() => {
-		if (
-			!isFullDataLoaded &&
-			traceData &&
-			traceData.payload &&
-			traceData.payload.uncollapsedSpans
-		) {
-			setUncollapsedNodes(traceData.payload.uncollapsedSpans);
-		}
-	}, [traceData, isFullDataLoaded]);
-
-	// Tracks whether we've already done the initial URL→selectedSpan handoff
-	//Lets `interestedSpanId` stay purely as the refetch trigger in frontend mode.
-	useEffect(() => {
-		if (deepLinkResolvedRef.current) {
-			return;
-		}
-		if (allSpans.length === 0) {
-			return;
-		}
-		if (selectedSpanId) {
-			const span = allSpans.find((s) => s.span_id === selectedSpanId);
-			if (!span) {
-				// Span not in the current window — wait for more data (backend
-				// pagination) before marking resolved.
-				return;
-			}
-			setSelectedSpan(span);
-		} else {
-			setSelectedSpan((prev) => prev ?? allSpans[0]);
-		}
-		deepLinkResolvedRef.current = true;
-	}, [selectedSpanId, allSpans]);
-
-	// Frontend mode: auto-expand ancestors of the URL-targeted span so it's
-	// visible. Keyed on URL `spanId`(selectedSpanId).
-	useEffect(() => {
-		if (!isFullDataLoaded || !selectedSpanId || allSpans.length === 0) {
-			return;
-		}
-		const ancestors = getAncestorSpanIds(allSpans, selectedSpanId);
-		if (ancestors.size === 0) {
-			return;
-		}
-		setLocalUncollapsedNodes((prev) => {
-			// Check if all ancestors are already expanded — avoid unnecessary state update
-			let allPresent = true;
-			for (const id of ancestors) {
-				if (!prev.has(id)) {
-					allPresent = false;
-					break;
-				}
-			}
-			if (allPresent) {
-				return prev;
-			}
-
-			const next = new Set(prev);
-			for (const id of ancestors) {
-				next.add(id);
-			}
-			return next;
-		});
-	}, [isFullDataLoaded, selectedSpanId, allSpans]);
-
-	const [activeKeys, setActiveKeys] = useState<string[]>(['flame', 'waterfall']);
-
-	const handleCollapseChange = (key: string): void => {
-		logTraceEvent(
-			key === 'flame'
-				? TraceDetailEvents.FlameGraphToggled
-				: TraceDetailEvents.WaterfallToggled,
-			{ [TraceDetailEventKeys.Expanded]: !activeKeys.includes(key) },
-		);
-		setActiveKeys((prev) =>
-			prev.includes(key) ? prev.filter((k) => k !== key) : [...prev, key],
-		);
-	};
-
-	const [spanDetailVariant, setSpanDetailVariant] = useState<SpanDetailVariant>(
-		() =>
-			(getLocalStorageKey(
-				LOCALSTORAGE.TRACE_DETAILS_SPAN_DETAILS_POSITION,
-			) as SpanDetailVariant) || SpanDetailVariant.DOCKED_RIGHT,
-	);
-
-	const RIGHT_DOCK_MIN = 480;
-	const RIGHT_DOCK_MAX = 720;
-	const [rightDockWidth, setRightDockWidth] = useState(RIGHT_DOCK_MIN);
-
-	const handleVariantChange = useCallback(
-		(newVariant: SpanDetailVariant): void => {
-			setLocalStorageKey(
-				LOCALSTORAGE.TRACE_DETAILS_SPAN_DETAILS_POSITION,
-				newVariant,
-			);
-			setSpanDetailVariant(newVariant);
-		},
-		[],
-	);
-
-	const showNoData =
-		!isFetchingTraceData &&
-		(!!errorFetchingTraceData || !traceData?.payload?.spans?.length);
-
-	const isDocked = spanDetailVariant === SpanDetailVariant.DOCKED;
-	const isRightDocked = spanDetailVariant === SpanDetailVariant.DOCKED_RIGHT;
-	const isWaterfallDocked = panelState.isOpen && isDocked;
-	const showRightDock = panelState.isOpen && isRightDocked;
-
-	const waterfallChildren = (
-		<ResizableBox
-			defaultHeight={300}
-			minHeight={150}
-			disabled={!isWaterfallDocked}
-		>
-			<TraceWaterfall
-				traceData={traceData}
-				isFetchingTraceData={isFetchingTraceData}
-				errorFetchingTraceData={errorFetchingTraceData}
-				traceId={traceId || ''}
-				interestedSpanId={interestedSpanId}
-				setInterestedSpanId={setInterestedSpanId}
-				uncollapsedNodes={uncollapsedNodes}
-				isFullDataLoaded={isFullDataLoaded}
-				localUncollapsedNodes={localUncollapsedNodes}
-				setLocalUncollapsedNodes={setLocalUncollapsedNodes}
-				selectedSpan={selectedSpan}
-				setSelectedSpan={setSelectedSpan}
-				filteredSpanIds={filteredSpanIds}
-				isFilterActive={isFilterActive}
-			/>
-		</ResizableBox>
-	);
+	}, [isOverview, handleFilteredSpansChange]);
 
 	return (
-		<TraceStoreSync availableColorByFields={availableColorByFields}>
-			<div className={styles.root}>
-				<TraceDetailsHeader
-					onFilteredSpansChange={handleFilteredSpansChange}
-					showTraceDetailsHeaderOptions={
-						!!traceData?.payload?.spans?.length && !showNoData
-					}
+		<TraceDetailsWrapper>
+			<TraceDetailsHeader
+				onFilteredSpansChange={handleFilteredSpansChange}
+				showTraceDetailsHeaderOptions={hasTraceData}
+			/>
+			{isOverview ? (
+				<TraceDetailsOverview
+					filteredSpanIds={filteredSpanIds}
+					isFilterActive={isFilterActive}
+					onHasTraceDataChange={setHasTraceData}
 				/>
-
-				{showNoData ? (
-					<NoData />
-				) : (
-					<>
-						<div className={styles.layoutRow}>
-							<div className={styles.content}>
-								<Collapse
-									// @ts-expect-error motion is passed through to rc-collapse to disable animation
-									motion={false}
-									activeKey={activeKeys.filter((k) => k === 'flame')}
-									onChange={(): void => handleCollapseChange('flame')}
-									size="small"
-									expandIcon={renderPanelExpandIcon}
-									className={styles.flameCollapse}
-									items={[
-										{
-											key: 'flame',
-											label: (
-												<div className={styles.collapseLabel}>
-													<span className={styles.collapseTitle}>
-														Flame Graph
-														{traceData?.payload?.totalSpansCount &&
-															traceData.payload.totalSpansCount > FLAMEGRAPH_SPAN_LIMIT && (
-																<WarningPopover
-																	message="The total span count exceeds the visualization limit. Displaying a sampled subset of spans in flamegraph."
-																	placement="bottomLeft"
-																>
-																	<Info
-																		size={16}
-																		color="var(--l2-foreground)"
-																		style={{ cursor: 'pointer' }}
-																	/>
-																</WarningPopover>
-															)}
-													</span>
-													{traceData?.payload?.totalSpansCount ? (
-														<span className={styles.collapseCount}>
-															<span className={styles.collapseCountItem}>
-																<ChartNoAxesGantt size={13} />
-																Spans: {traceData.payload.totalSpansCount}
-															</span>
-															<span
-																className={cx(styles.collapseCountItem, {
-																	[styles.hasErrors]: traceData.payload.totalErrorSpansCount > 0,
-																})}
-															>
-																<TriangleAlert size={13} />
-																Errors:{' '}
-																{traceData.payload.totalErrorSpansCount ?? (
-																	<span className="translate-safe">{0}</span>
-																)}
-															</span>
-														</span>
-													) : null}
-												</div>
-											),
-											children: (
-												<ResizableBox defaultHeight={300} minHeight={100} maxHeight={400}>
-													<TraceFlamegraph
-														filteredSpanIds={filteredSpanIds}
-														isFilterActive={isFilterActive}
-														selectedSpan={selectedSpan}
-														totalSpansCount={totalSpansCount}
-													/>
-												</ResizableBox>
-											),
-										},
-									]}
-								/>
-
-								<Collapse
-									// @ts-expect-error motion is passed through to rc-collapse to disable animation
-									motion={false}
-									activeKey={activeKeys.filter((k) => k === 'waterfall')}
-									onChange={(): void => handleCollapseChange('waterfall')}
-									size="small"
-									expandIcon={renderPanelExpandIcon}
-									className={cx(styles.waterfallCollapse, {
-										[styles.isDocked]: isWaterfallDocked,
-									})}
-									items={[
-										{
-											key: 'waterfall',
-											label: 'Waterfall',
-											children: activeKeys.includes('waterfall')
-												? waterfallChildren
-												: null,
-										},
-									]}
-								/>
-
-								{panelState.isOpen && isDocked && (
-									<div className={styles.dockedSpanDetails}>
-										<SpanDetailsPanel
-											panelState={panelState}
-											selectedSpan={selectedSpan}
-											variant={SpanDetailVariant.DOCKED}
-											onVariantChange={handleVariantChange}
-											traceStartTime={traceData?.payload?.startTimestampMillis}
-											traceEndTime={traceData?.payload?.endTimestampMillis}
-										/>
-									</div>
-								)}
-							</div>
-
-							{showRightDock && (
-								<ResizableBox
-									handle="left"
-									defaultWidth={rightDockWidth}
-									minWidth={RIGHT_DOCK_MIN}
-									maxWidth={RIGHT_DOCK_MAX}
-									onResize={setRightDockWidth}
-									className={styles.rightDock}
-								>
-									<SpanDetailsPanel
-										panelState={panelState}
-										selectedSpan={selectedSpan}
-										variant={SpanDetailVariant.DOCKED_RIGHT}
-										onVariantChange={handleVariantChange}
-										traceStartTime={traceData?.payload?.startTimestampMillis}
-										traceEndTime={traceData?.payload?.endTimestampMillis}
-									/>
-								</ResizableBox>
-							)}
-						</div>
-
-						{panelState.isOpen && spanDetailVariant === SpanDetailVariant.DIALOG && (
-							<SpanDetailsPanel
-								panelState={panelState}
-								selectedSpan={selectedSpan}
-								variant={SpanDetailVariant.DIALOG}
-								onVariantChange={handleVariantChange}
-								traceStartTime={traceData?.payload?.startTimestampMillis}
-								traceEndTime={traceData?.payload?.endTimestampMillis}
-							/>
-						)}
-					</>
-				)}
-			</div>
-		</TraceStoreSync>
+			) : (
+				<TraceDetailsThread />
+			)}
+		</TraceDetailsWrapper>
 	);
 }
 

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

@@ -0,0 +1,45 @@
+/* Figma `dark/shadow-dropdown` popover surface, shared by every trace-details
+   tooltip so they look the same. */
+
+/* Plain CSS only (no SCSS syntax): other modules `composes` from this file. */
+
+/* For plain elements, e.g. the flamegraph's cursor-following portal. */
+.tooltipSurface {
+	background-color: color-mix(in srgb, var(--l3-background) 60%, transparent);
+	border: 1px solid var(--l2-border);
+	border-radius: var(--radius-2);
+	padding: var(--spacing-4);
+	box-shadow: 4px 10px 16px 2px rgba(0, 0, 0, 0.2);
+	backdrop-filter: blur(20px);
+}
+
+/* For @signozhq/ui Tooltip content: it paints both the bubble and the arrow
+   from these variables. */
+.tooltipContent {
+	--tooltip-background: color-mix(
+		in srgb,
+		var(--l3-background) 60%,
+		transparent
+	);
+	--tooltip-border-color: var(--l2-border);
+	--tooltip-border-radius: var(--radius-2);
+	--tooltip-padding: var(--spacing-4);
+	--tooltip-box-shadow: 4px 10px 16px 2px rgba(0, 0, 0, 0.2);
+	backdrop-filter: blur(20px);
+}
+
+.tooltipBody {
+	display: flex;
+	flex-direction: column;
+	letter-spacing: var(--paragraph-small-400-letter-spacing);
+	color: var(--l1-foreground-hover);
+}
+
+.tooltipTitle {
+	--typography-font-family: var(--code-small-500-font-family);
+	--typography-font-size: var(--code-small-500-font-size);
+	--typography-font-weight: var(--code-small-500-font-weight);
+	--typography-line-height: var(--code-small-500-line-height);
+	letter-spacing: var(--code-small-500-letter-spacing);
+	word-break: break-all;
+}

frontend/src/pages/TraceDetailsV3/stores/TraceStoreSync.tsx

@@ -4,36 +4,28 @@ import updateUserPreferenceAPI from 'api/v1/user/preferences/name/update';
 import { useAppContext } from 'providers/App/App';
 
 import {
-	setTraceStoreAvailableColorByFields,
 	setTraceStoreCallbacks,
 	setTraceStoreUserPreferences,
 } from './traceStore';
 
 interface TraceStoreSyncProps {
-	availableColorByFields: string[] | undefined;
 	children: ReactNode;
 }
 
 /**
- * Bridges React-managed inputs (`availableColorByFields`, `userPreferences`
- * from AppContext, and the user-pref mutation hook) into the Zustand store.
+ * Bridges React-managed inputs (`userPreferences` from AppContext and the
+ * user-pref mutation hook) into the Zustand store. `availableColorByFields`
+ * is pushed by TraceDetailsOverview, which owns the span data.
  *
  * Renders nothing until `userPreferences` resolves so the flamegraph never
  * paints with the default colour first and then swaps to the user's
  * persisted choice. AppProvider fires the prefs query as soon as the user
  * is logged in, so this gate is usually already settled by mount time.
  */
-function TraceStoreSync({
-	availableColorByFields,
-	children,
-}: TraceStoreSyncProps): JSX.Element | null {
+function TraceStoreSync({ children }: TraceStoreSyncProps): JSX.Element | null {
 	const { userPreferences, updateUserPreferenceInContext } = useAppContext();
 	const { mutate: mutateUserPreference } = useMutation(updateUserPreferenceAPI);
 
-	useEffect(() => {
-		setTraceStoreAvailableColorByFields(availableColorByFields);
-	}, [availableColorByFields]);
-
 	useEffect(() => {
 		setTraceStoreUserPreferences(userPreferences ?? null);
 	}, [userPreferences]);

frontend/src/pages/TraceDetailsV3/stores/traceStore.ts

@@ -37,7 +37,7 @@ interface TraceStoreState {
 	availableColorByOptions: ColorByOption[];
 	previewFields: TelemetryFieldKey[];
 
-	// --- Setters used only by TraceStoreSync ---
+	// --- Setters used only by TraceStoreSync and TraceDetailsOverview ---
 	setAvailableColorByFields: (fieldNames: string[] | undefined) => void;
 	setUserPreferences: (userPreferences: UserPreference[] | null) => void;
 	setCallbacks: (callbacks: {

frontend/src/pages/TraceDetailsV3/utils/__tests__/genAi.test.ts

@@ -0,0 +1,32 @@
+import { SpanV3 } from 'types/api/trace/getTraceV3';
+
+import { AiSpanKind, getAiSpanKind, isAiSpan } from '../genAi';
+
+const spanWith = (attributes: Record<string, string | number>): SpanV3 =>
+	({ attributes, resource: {} }) as unknown as SpanV3;
+
+describe('getAiSpanKind', () => {
+	it.each<[Record<string, string | number>, AiSpanKind]>([
+		[{ 'gen_ai.request.model': 'gpt-4o' }, AiSpanKind.Llm],
+		[{ 'gen_ai.usage.input_tokens': 0 }, AiSpanKind.Llm],
+		[{ 'gen_ai.usage.reasoning.output_tokens': 12 }, AiSpanKind.Llm],
+		[{ 'gen_ai.tool.name': 'search' }, AiSpanKind.Tool],
+		[{ 'gen_ai.agent.name': 'planner' }, AiSpanKind.Agent],
+		[
+			{ 'gen_ai.tool.name': 'search', 'gen_ai.request.model': 'gpt-4o' },
+			AiSpanKind.Tool,
+		],
+		[
+			{ 'gen_ai.agent.name': 'planner', 'gen_ai.usage.input_tokens': 10 },
+			AiSpanKind.Agent,
+		],
+	])('classifies %p as %s', (attributes, kind) => {
+		expect(getAiSpanKind(spanWith(attributes))).toBe(kind);
+	});
+
+	it('returns undefined for non-AI spans and empty values', () => {
+		expect(getAiSpanKind(spanWith({ 'http.method': 'GET' }))).toBeUndefined();
+		expect(getAiSpanKind(spanWith({ 'gen_ai.tool.name': '' }))).toBeUndefined();
+		expect(isAiSpan(spanWith({}))).toBe(false);
+	});
+});

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

@@ -0,0 +1,69 @@
+import { SpanV3 } from 'types/api/trace/getTraceV3';
+
+export const GEN_AI_KEYS = {
+	requestModel: 'gen_ai.request.model',
+	toolName: 'gen_ai.tool.name',
+	agentName: 'gen_ai.agent.name',
+	inputTokens: 'gen_ai.usage.input_tokens',
+	outputTokens: 'gen_ai.usage.output_tokens',
+	cacheReadTokens: 'gen_ai.usage.cache_read.input_tokens',
+	cacheCreationTokens: 'gen_ai.usage.cache_creation.input_tokens',
+	reasoningTokens: 'gen_ai.usage.reasoning.output_tokens',
+	cost: 'signoz.gen_ai.usage.tokens.cost',
+	inputMessages: 'gen_ai.input.messages',
+	outputMessages: 'gen_ai.output.messages',
+} as const;
+
+export enum AiSpanKind {
+	Llm = 'llm',
+	Tool = 'tool',
+	Agent = 'agent',
+}
+
+const LLM_KEYS = [
+	GEN_AI_KEYS.requestModel,
+	GEN_AI_KEYS.inputTokens,
+	GEN_AI_KEYS.outputTokens,
+	GEN_AI_KEYS.cacheReadTokens,
+	GEN_AI_KEYS.cacheCreationTokens,
+	GEN_AI_KEYS.reasoningTokens,
+];
+
+/** Keeps numeric 0, which `getSpanAttribute`'s `||` chain drops. */
+export function getGenAiValue(
+	span: SpanV3,
+	key: string,
+): string | number | boolean | undefined {
+	const value = span.attributes?.[key] ?? span.resource?.[key];
+	return value === '' ? undefined : value;
+}
+
+function hasAttribute(span: SpanV3, key: string): boolean {
+	return getGenAiValue(span, key) !== undefined;
+}
+
+/** Tool and agent spans may also carry model or usage keys, so they win over LLM. */
+export function getAiSpanKind(span: SpanV3): AiSpanKind | undefined {
+	if (hasAttribute(span, GEN_AI_KEYS.toolName)) {
+		return AiSpanKind.Tool;
+	}
+	if (hasAttribute(span, GEN_AI_KEYS.agentName)) {
+		return AiSpanKind.Agent;
+	}
+	if (LLM_KEYS.some((key) => hasAttribute(span, key))) {
+		return AiSpanKind.Llm;
+	}
+	return undefined;
+}
+
+export function isAiSpan(span: SpanV3): boolean {
+	return getAiSpanKind(span) !== undefined;
+}
+
+export function formatTokens(value: number): string {
+	return value.toLocaleString('en-US');
+}
+
+export function formatCost(value: number): string {
+	return `$ ${value.toLocaleString('en-US', { maximumFractionDigits: 10 })}`;
+}