refactor(ai-assistant): apply ActivityGroup review feedback

- Rename common CSS module class names to scoped variants
  (.group → .activityGroup, .header → .activityHeader, etc.) so
  matches against module classes carry intent and don't collide
  with future styles in adjacent files.
- Swap the disclosure <button> for a <div> with onClick — drops the
  signoz Button component option since its action-button defaults
  (focus ring, base padding, hover background) visually regressed
  the quiet full-width row. Matches the existing ThinkingStep /
  ToolCallStep disclosure pattern.
- Drop the useId + aria-controls plumbing; with the disclosure
  collapsed inline beneath the header, the id wasn't carrying
  semantic weight beyond what aria-expanded already provides.
- Thread stable id fields through ActivityItem and the RenderGroup
  types so list keys come from typed data rather than the loop
  index. Persisted tool blocks key off the server-assigned
  toolCallId; streaming items and thinking blocks key off their
  position in the append-only source array.

frontend/src/container/AIAssistant/components/ActivityGroup/ActivityGroup.module.scss

@@ -0,0 +1,64 @@
+// Collapsed activity summary — one row that hides the underlying
+// thinking + tool-call steps. Reuses the same quiet treatment as
+// ThinkingStep / ToolCallStep so it sits flush in the assistant bubble.
+.activityGroup {
+	width: 100%;
+	font-size: 12px;
+}
+
+.activityHeader {
+	display: flex;
+	align-items: center;
+	gap: 8px;
+	padding: 4px 0;
+	background: transparent;
+	border: none;
+	cursor: pointer;
+	color: var(--l3-foreground);
+	user-select: none;
+	transition: color 0.12s ease;
+	width: 100%;
+	text-align: left;
+
+	&:hover {
+		color: var(--l1-foreground);
+	}
+}
+
+.sparkleIcon {
+	flex-shrink: 0;
+	color: var(--accent-primary);
+
+	&.iconPulsing {
+		animation: activityGroupPulse 1.4s ease-in-out infinite;
+	}
+}
+
+@keyframes activityGroupPulse {
+	0%,
+	100% {
+		opacity: 0.55;
+	}
+	50% {
+		opacity: 1;
+	}
+}
+
+.activitySummary {
+	flex: 1;
+	overflow: hidden;
+	text-overflow: ellipsis;
+	white-space: nowrap;
+	font-weight: 400;
+}
+
+.toggleChevron {
+	flex-shrink: 0;
+	color: inherit;
+}
+
+.activityBody {
+	display: flex;
+	flex-direction: column;
+	padding: 2px 0 4px;
+}

frontend/src/container/AIAssistant/components/ActivityGroup/ActivityGroup.tsx

@@ -0,0 +1,148 @@
+import { useEffect, useRef, useState } from 'react';
+import cx from 'classnames';
+import { ChevronDown, ChevronRight, Sparkles } from '@signozhq/icons';
+
+import { formatTime } from 'utils/timeUtils';
+
+import { StreamingToolCall } from '../../types';
+import ThinkingStep, { ThinkingContent, thinkingLabel } from '../ThinkingStep';
+import ToolCallStep, {
+	getToolDisplayLabel,
+	ToolCallContent,
+} from '../ToolCallStep';
+
+import styles from './ActivityGroup.module.scss';
+
+export type ActivityItem =
+	| { id: string; kind: 'thinking'; content: string }
+	| { id: string; kind: 'tool'; toolCall: StreamingToolCall };
+
+interface ActivityGroupProps {
+	items: ActivityItem[];
+	/**
+	 * True only for the trailing activity group of an active stream — drives
+	 * the live "Working…" label and the elapsed-time tick (which re-stamps on
+	 * approval/clarification resume so wait time isn't counted).
+	 */
+	isLive?: boolean;
+}
+
+/**
+ * Single-item groups get a step-specific summary so the user doesn't see a
+ * pointless "Worked through 1 step". Multi-item groups roll up into the
+ * generic "Working… / Worked through N steps" treatment.
+ */
+function buildSummary(
+	items: ActivityItem[],
+	isLive: boolean,
+	elapsed: number,
+): string {
+	if (items.length === 1) {
+		const [only] = items;
+		if (only.kind === 'thinking') {
+			return thinkingLabel(isLive);
+		}
+		return getToolDisplayLabel(only.toolCall);
+	}
+	const stepLabel = `${items.length} steps`;
+	if (!isLive) {
+		return `Worked through ${stepLabel}`;
+	}
+	// Suppress the elapsed token until ≥ 1s — the first tick fires after
+	// 1s anyway, and showing "0s" or "<1s" briefly adds noise.
+	return elapsed >= 1000
+		? `Working… · ${formatTime(elapsed / 1000)} · ${stepLabel}`
+		: `Working… · ${stepLabel}`;
+}
+
+/**
+ * Single collapsed summary row that hides a run of thinking + tool-call steps.
+ * Expands to show each underlying step inline. Used for every activity row
+ * (including single-item ones) so all "what the agent did" rows share a
+ * consistent ✨-led visual contract.
+ */
+export default function ActivityGroup({
+	items,
+	isLive = false,
+}: ActivityGroupProps): JSX.Element {
+	const [expanded, setExpanded] = useState(false);
+
+	// Captures the moment this live phase started. Re-stamped on every
+	// false→true transition so a stream that pauses on
+	// approval/clarification and resumes doesn't roll the user's wait time
+	// into the elapsed counter.
+	const startedAtRef = useRef<number>(Date.now());
+	const wasLiveRef = useRef<boolean>(isLive);
+	const [elapsed, setElapsed] = useState(0);
+
+	useEffect(() => {
+		if (isLive && !wasLiveRef.current) {
+			startedAtRef.current = Date.now();
+			setElapsed(0);
+		}
+		wasLiveRef.current = isLive;
+
+		if (!isLive) {
+			return undefined;
+		}
+		// Tick once per second — the display is integer-second precision, so
+		// faster ticks would just re-render the bubble for no visible change.
+		const id = window.setInterval(() => {
+			setElapsed(Date.now() - startedAtRef.current);
+		}, 1000);
+		return (): void => window.clearInterval(id);
+	}, [isLive]);
+
+	const summary = buildSummary(items, isLive, elapsed);
+	const isSingle = items.length === 1;
+
+	const toggle = (): void => setExpanded((v) => !v);
+
+	return (
+		<div className={styles.activityGroup}>
+			<div className={styles.activityHeader} onClick={toggle}>
+				<Sparkles
+					size={12}
+					className={cx(styles.sparkleIcon, { [styles.iconPulsing]: isLive })}
+				/>
+				<span className={styles.activitySummary}>{summary}</span>
+				{expanded ? (
+					<ChevronDown size={12} className={styles.toggleChevron} />
+				) : (
+					<ChevronRight size={12} className={styles.toggleChevron} />
+				)}
+			</div>
+
+			{expanded && (
+				<div className={styles.activityBody}>
+					{isSingle ? (
+						// Single-item: the outer chevron already provides disclosure,
+						// so render the underlying content directly instead of wrapping
+						// it in a second collapsible step row.
+						items[0].kind === 'thinking' ? (
+							<ThinkingContent content={items[0].content} />
+						) : (
+							<ToolCallContent toolCall={items[0].toolCall} />
+						)
+					) : (
+						items.map((item, i) => {
+							// A thinking step is live only while it's the trailing item
+							// in a trailing live group — once any later event (text or
+							// tool) arrives, the pass is done.
+							const isLastItem = i === items.length - 1;
+							return item.kind === 'thinking' ? (
+								<ThinkingStep
+									key={item.id}
+									content={item.content}
+									isLive={isLive && isLastItem}
+								/>
+							) : (
+								<ToolCallStep key={item.id} toolCall={item.toolCall} />
+							);
+						})
+					)}
+				</div>
+			)}
+		</div>
+	);
+}

frontend/src/container/AIAssistant/components/ActivityGroup/index.ts

@@ -0,0 +1,2 @@
+export { default } from './ActivityGroup';
+export type { ActivityItem } from './ActivityGroup';

frontend/src/container/AIAssistant/components/MessageBubble/MessageBubble.tsx

@@ -1,4 +1,4 @@
-import React from 'react';
+import React, { useMemo } from 'react';
 import cx from 'classnames';
 import ReactMarkdown from 'react-markdown';
 import remarkGfm from 'remark-gfm';
@@ -9,11 +9,10 @@ import '../blocks';
 import { useVariant } from '../../VariantContext';
 import { Message, MessageBlock } from '../../types';
 import ActionsSection from '../ActionsSection';
+import ActivityGroup, { ActivityItem } from '../ActivityGroup';
 import { RichCodeBlock } from '../blocks';
 import { MessageContext } from '../MessageContext';
 import MessageFeedback from '../MessageFeedback';
-import ThinkingStep from '../ThinkingStep';
-import ToolCallStep from '../ToolCallStep';
 import UserMessageActions from '../UserMessageActions';
 
 import styles from './MessageBubble.module.scss';
@@ -40,38 +39,61 @@ function SmartPre({ children }: { children?: React.ReactNode }): JSX.Element {
 const MD_PLUGINS = [remarkGfm];
 const MD_COMPONENTS = { code: RichCodeBlock, pre: SmartPre };
 
-/** Renders a single MessageBlock by type. */
-function renderBlock(block: MessageBlock, index: number): JSX.Element {
-	switch (block.type) {
-		case 'thinking':
-			return <ThinkingStep key={index} content={block.content} />;
-		case 'tool_call':
-			// Blocks in a persisted message are always complete — done is always true.
-			return (
-				<ToolCallStep
-					key={index}
-					toolCall={{
-						toolName: block.toolName,
-						input: block.toolInput,
-						result: block.result,
-						done: true,
-						displayText: block.displayText,
-					}}
-				/>
-			);
-		case 'text':
-		default:
-			return (
-				<ReactMarkdown
-					key={index}
-					className={styles.markdown}
-					remarkPlugins={MD_PLUGINS}
-					components={MD_COMPONENTS}
-				>
-					{block.content}
-				</ReactMarkdown>
-			);
+type RenderGroup =
+	| { kind: 'text'; id: string; content: string }
+	| { kind: 'activity'; id: string; items: ActivityItem[] };
+
+/**
+ * Partition message blocks into render groups so consecutive thinking and
+ * tool_call blocks collapse into a single ActivityGroup row. Text blocks
+ * stand alone, mirroring the streaming view.
+ */
+function groupBlocks(blocks: MessageBlock[]): RenderGroup[] {
+	const groups: RenderGroup[] = [];
+	blocks.forEach((block, i) => {
+		if (block.type === 'text') {
+			groups.push({ kind: 'text', id: `text-${i}`, content: block.content });
+			return;
+		}
+		const item: ActivityItem =
+			block.type === 'thinking'
+				? { id: `t-${i}`, kind: 'thinking', content: block.content }
+				: {
+						id: `c-${block.toolCallId}`,
+						kind: 'tool',
+						// Persisted blocks are always complete.
+						toolCall: {
+							toolName: block.toolName,
+							input: block.toolInput,
+							result: block.result,
+							done: true,
+							displayText: block.displayText,
+						},
+					};
+		const last = groups[groups.length - 1];
+		if (last?.kind === 'activity') {
+			last.items.push(item);
+		} else {
+			groups.push({ kind: 'activity', id: `a-${i}`, items: [item] });
+		}
+	});
+	return groups;
+}
+
+function renderGroup(group: RenderGroup): JSX.Element {
+	if (group.kind === 'text') {
+		return (
+			<ReactMarkdown
+				key={group.id}
+				className={styles.markdown}
+				remarkPlugins={MD_PLUGINS}
+				components={MD_COMPONENTS}
+			>
+				{group.content}
+			</ReactMarkdown>
+		);
 	}
+	return <ActivityGroup key={group.id} items={group.items} />;
 }
 
 interface MessageBubbleProps {
@@ -90,6 +112,14 @@ export default function MessageBubble({
 	const isUser = message.role === 'user';
 	const hasBlocks = !isUser && message.blocks && message.blocks.length > 0;
 
+	// Recompute groups only when the blocks array identity changes — store
+	// updates that don't touch this message's blocks should not re-render the
+	// underlying ThinkingStep/ToolCallStep children.
+	const groups = useMemo(
+		() => (hasBlocks ? groupBlocks(message.blocks!) : []),
+		[hasBlocks, message.blocks],
+	);
+
 	const messageClass = cx(
 		styles.message,
 		isUser ? styles.user : styles.assistant,
@@ -128,8 +158,7 @@ export default function MessageBubble({
 							<p className={styles.text}>{message.content}</p>
 						) : hasBlocks ? (
 							<MessageContext.Provider value={{ messageId: message.id }}>
-								{/* eslint-disable-next-line react/no-array-index-key */}
-								{message.blocks!.map((block, i) => renderBlock(block, i))}
+								{groups.map((g) => renderGroup(g))}
 							</MessageContext.Provider>
 						) : (
 							<MessageContext.Provider value={{ messageId: message.id }}>

frontend/src/container/AIAssistant/components/StreamingMessage/StreamingMessage.tsx

@@ -1,4 +1,4 @@
-import React from 'react';
+import React, { useMemo } from 'react';
 import cx from 'classnames';
 import ReactMarkdown from 'react-markdown';
 import remarkGfm from 'remark-gfm';
@@ -10,11 +10,10 @@ import type {
 
 import { useVariant } from '../../VariantContext';
 import { StreamingEventItem } from '../../types';
+import ActivityGroup, { ActivityItem } from '../ActivityGroup';
 import ApprovalCard from '../ApprovalCard';
 import { RichCodeBlock } from '../blocks';
 import ClarificationForm from '../ClarificationForm';
-import ThinkingStep from '../ThinkingStep';
-import ToolCallStep from '../ToolCallStep';
 
 import messageStyles from '../MessageBubble/MessageBubble.module.scss';
 import styles from './StreamingMessage.module.scss';
@@ -33,6 +32,59 @@ function SmartPre({ children }: { children?: React.ReactNode }): JSX.Element {
 const MD_PLUGINS = [remarkGfm];
 const MD_COMPONENTS = { code: RichCodeBlock, pre: SmartPre };
 
+type RenderGroup =
+	| { kind: 'text'; id: string; content: string }
+	| {
+			kind: 'activity';
+			id: string;
+			items: ActivityItem[];
+			isTrailing: boolean;
+	  };
+
+/**
+ * Partition the streaming event timeline into render groups: runs of
+ * consecutive thinking/tool events fold into a single activity group, text
+ * events stay standalone. The last group is flagged as trailing so the
+ * caller can drive a "live" indicator on it.
+ *
+ * Invariant relied on by the ActivityGroup elapsed-time timer: once a
+ * group exists at a given array index, later events only extend its
+ * `items` — they never shrink the array or re-key existing groups. That
+ * keeps each ActivityGroup React instance stable across re-renders so the
+ * timer's `wasLive` → `isLive` re-stamp captures the right transition.
+ * The id fields below piggyback on that invariant: each event's position in
+ * `events` is stable, so the derived id stays stable across re-renders.
+ */
+function groupStreamingEvents(events: StreamingEventItem[]): RenderGroup[] {
+	const groups: RenderGroup[] = [];
+	events.forEach((event, i) => {
+		if (event.kind === 'text') {
+			groups.push({ kind: 'text', id: `text-${i}`, content: event.content });
+			return;
+		}
+		const item: ActivityItem =
+			event.kind === 'thinking'
+				? { id: `t-${i}`, kind: 'thinking', content: event.content }
+				: { id: `c-${i}`, kind: 'tool', toolCall: event.toolCall };
+		const last = groups[groups.length - 1];
+		if (last?.kind === 'activity') {
+			last.items.push(item);
+		} else {
+			groups.push({
+				kind: 'activity',
+				id: `a-${i}`,
+				items: [item],
+				isTrailing: false,
+			});
+		}
+	});
+	const last = groups[groups.length - 1];
+	if (last?.kind === 'activity') {
+		last.isTrailing = true;
+	}
+	return groups;
+}
+
 /** Human-readable labels for execution status codes shown before any events arrive. */
 const STATUS_LABEL: Record<string, string> = {
 	queued: 'Queued…',
@@ -79,6 +131,11 @@ export default function StreamingMessage({
 		[messageStyles.compact]: isCompact,
 	});
 
+	// Recompute groups only when the events array identity changes. The
+	// streaming reducer pushes new entries into the same array reference
+	// once per tick, so this naturally invalidates as events arrive.
+	const groups = useMemo(() => groupStreamingEvents(events), [events]);
+
 	return (
 		<div className={messageClass}>
 			<div className={messageStyles.bubble}>
@@ -88,27 +145,28 @@ export default function StreamingMessage({
 				)}
 				{isEmpty && !statusLabel && <TypingDots />}
 
-				{/* eslint-disable react/no-array-index-key */}
-				{/* Events rendered in arrival order: text, thinking, and tool calls interleaved */}
-				{events.map((event, i) => {
-					if (event.kind === 'tool') {
-						return <ToolCallStep key={i} toolCall={event.toolCall} />;
-					}
-					if (event.kind === 'thinking') {
-						return <ThinkingStep key={i} content={event.content} />;
+				{/* Runs of consecutive thinking + tool events collapse into a
+				    single ActivityGroup; text events render inline between
+				    them. The trailing group is "live" while streaming is
+				    active and not blocked on the user. */}
+				{groups.map((group) => {
+					if (group.kind === 'text') {
+						return (
+							<ReactMarkdown
+								key={group.id}
+								className={messageStyles.markdown}
+								remarkPlugins={MD_PLUGINS}
+								components={MD_COMPONENTS}
+							>
+								{group.content}
+							</ReactMarkdown>
+						);
 					}
+					const groupIsLive = group.isTrailing && !isWaitingOnUser;
 					return (
-						<ReactMarkdown
-							key={i}
-							className={messageStyles.markdown}
-							remarkPlugins={MD_PLUGINS}
-							components={MD_COMPONENTS}
-						>
-							{event.content}
-						</ReactMarkdown>
+						<ActivityGroup key={group.id} items={group.items} isLive={groupIsLive} />
 					);
 				})}
-				{/* eslint-enable react/no-array-index-key */}
 
 				{/* While events are still streaming, append the typing dots so the
 				    user has a clear "more is coming" signal. Hidden when the agent

frontend/src/container/AIAssistant/components/ThinkingStep/ThinkingStep.tsx

@@ -5,11 +5,31 @@ import styles from './ThinkingStep.module.scss';
 
 interface ThinkingStepProps {
 	content: string;
+	/**
+	 * When false, label reads "Thought for a few seconds" — intentionally
+	 * vague because the API doesn't persist precise timing, so showing
+	 * seconds would be inconsistent between fresh and reloaded threads.
+	 */
+	isLive?: boolean;
+}
+
+/** Body of a thinking step — extracted so ActivityGroup can render it directly. */
+export function ThinkingContent({ content }: { content: string }): JSX.Element {
+	return (
+		<div className={styles.body}>
+			<p className={styles.content}>{content}</p>
+		</div>
+	);
+}
+
+export function thinkingLabel(isLive: boolean): string {
+	return isLive ? 'Thinking…' : 'Thought for a few seconds';
 }
 
 /** Collapsible thinking row — chevron + label, content in the expanded body. */
 export default function ThinkingStep({
 	content,
+	isLive = false,
 }: ThinkingStepProps): JSX.Element {
 	const [expanded, setExpanded] = useState(false);
 
@@ -23,14 +43,10 @@ export default function ThinkingStep({
 				) : (
 					<ChevronRight size={12} className={styles.chevron} />
 				)}
-				<span className={styles.label}>Thinking</span>
+				<span className={styles.label}>{thinkingLabel(isLive)}</span>
 			</div>
 
-			{expanded && (
-				<div className={styles.body}>
-					<p className={styles.content}>{content}</p>
-				</div>
-			)}
+			{expanded && <ThinkingContent content={content} />}
 		</div>
 	);
 }

frontend/src/container/AIAssistant/components/ToolCallStep/ToolCallStep.tsx

@@ -10,24 +10,58 @@ interface ToolCallStepProps {
 	toolCall: StreamingToolCall;
 }
 
+/**
+ * Server-supplied `displayText` is the human-friendly title the backend
+ * wants surfaced. Falls back to a derived label
+ * ("signoz_get_dashboard" → "Get Dashboard") when missing.
+ */
+export function getToolDisplayLabel(toolCall: StreamingToolCall): string {
+	const { toolName, displayText } = toolCall;
+	if (displayText && displayText.trim().length > 0) {
+		return displayText;
+	}
+	return toolName
+		.replace(/^[a-z]+_/, '') // strip prefix like "signoz_"
+		.replace(/_/g, ' ')
+		.replace(/\b\w/g, (c) => c.toUpperCase());
+}
+
+/** Body of a tool-call step — extracted so ActivityGroup can render it directly. */
+export function ToolCallContent({
+	toolCall,
+}: {
+	toolCall: StreamingToolCall;
+}): JSX.Element {
+	const { toolName, input, result, done } = toolCall;
+	return (
+		<div className={styles.body}>
+			<div className={styles.section}>
+				<span className={styles.sectionLabel}>Tool</span>
+				<span className={styles.toolName}>{toolName}</span>
+			</div>
+			<div className={styles.section}>
+				<span className={styles.sectionLabel}>Input</span>
+				<pre className={styles.json}>{JSON.stringify(input, null, 2)}</pre>
+			</div>
+			{done && result !== undefined && (
+				<div className={styles.section}>
+					<span className={styles.sectionLabel}>Output</span>
+					<pre className={styles.json}>
+						{typeof result === 'string' ? result : JSON.stringify(result, null, 2)}
+					</pre>
+				</div>
+			)}
+		</div>
+	);
+}
+
 /** Collapsible tool-call row — chevron + label, in/out detail in the body. */
 export default function ToolCallStep({
 	toolCall,
 }: ToolCallStepProps): JSX.Element {
 	const [expanded, setExpanded] = useState(false);
-	const { toolName, input, result, done, displayText } = toolCall;
-
-	// Prefer the server-supplied `displayText` from `ToolCallEventDTO` —
-	// it's the human-friendly title the backend wants surfaced. Fall back
-	// to a derived label ("signoz_get_dashboard" → "Get Dashboard") when
-	// the field is empty / null / missing.
-	const label =
-		displayText && displayText.trim().length > 0
-			? displayText
-			: toolName
-					.replace(/^[a-z]+_/, '') // strip prefix like "signoz_"
-					.replace(/_/g, ' ')
-					.replace(/\b\w/g, (c) => c.toUpperCase());
+	const { done } = toolCall;
+	const label = getToolDisplayLabel(toolCall);
 
 	const toggle = (): void => setExpanded((v) => !v);
 
@@ -44,26 +78,7 @@ export default function ToolCallStep({
 				<span className={styles.label}>{label}</span>
 			</div>
 
-			{expanded && (
-				<div className={styles.body}>
-					<div className={styles.section}>
-						<span className={styles.sectionLabel}>Tool</span>
-						<span className={styles.toolName}>{toolName}</span>
-					</div>
-					<div className={styles.section}>
-						<span className={styles.sectionLabel}>Input</span>
-						<pre className={styles.json}>{JSON.stringify(input, null, 2)}</pre>
-					</div>
-					{done && result !== undefined && (
-						<div className={styles.section}>
-							<span className={styles.sectionLabel}>Output</span>
-							<pre className={styles.json}>
-								{typeof result === 'string' ? result : JSON.stringify(result, null, 2)}
-							</pre>
-						</div>
-					)}
-				</div>
-			)}
+			{expanded && <ToolCallContent toolCall={toolCall} />}
 		</div>
 	);
 }