diff --git a/packages/ui/src/components/message-block-list.tsx b/packages/ui/src/components/message-block-list.tsx
index 02f81a5c..8e0c8159 100644
--- a/packages/ui/src/components/message-block-list.tsx
+++ b/packages/ui/src/components/message-block-list.tsx
@@ -3,6 +3,10 @@ import VirtualItem from "./virtual-item"
 import MessageBlock from "./message-block"
 import type { InstanceMessageStore } from "../stores/message-v2/instance-store"
 
+export function getMessageAnchorId(messageId: string) {
+  return `message-anchor-${messageId}`
+}
+
 const VIRTUAL_ITEM_MARGIN_PX = 800
 const ESTIMATED_MESSAGE_HEIGHT = 320
 const INITIAL_FORCE_MIN_ITEMS = 12
@@ -73,14 +77,16 @@ export default function MessageBlockList(props: MessageBlockListProps) {
           }
           return (
             <VirtualItem
-              cacheKey={messageId()}
-              scrollContainer={props.scrollContainer}
-              threshold={VIRTUAL_ITEM_MARGIN_PX}
-              placeholderClass="message-stream-placeholder"
-              virtualizationEnabled={() => !props.loading}
-              forceVisible={forceVisible}
-              onMeasured={handleMeasured}
-            >
+               id={getMessageAnchorId(messageId())}
+               cacheKey={messageId()}
+               scrollContainer={props.scrollContainer}
+               threshold={VIRTUAL_ITEM_MARGIN_PX}
+               placeholderClass="message-stream-placeholder"
+               virtualizationEnabled={() => !props.loading}
+               forceVisible={forceVisible}
+               onMeasured={handleMeasured}
+             >
+
               <MessageBlock
                 messageId={messageId()}
                 instanceId={props.instanceId}
diff --git a/packages/ui/src/components/message-section.tsx b/packages/ui/src/components/message-section.tsx
index 2c4dc5e0..e8a9826a 100644
--- a/packages/ui/src/components/message-section.tsx
+++ b/packages/ui/src/components/message-section.tsx
@@ -1,7 +1,8 @@
 import { Show, createEffect, createMemo, createSignal, onCleanup } from "solid-js"
 import Kbd from "./kbd"
-import MessageBlockList from "./message-block-list"
+import MessageBlockList, { getMessageAnchorId } from "./message-block-list"
 import MessageListHeader from "./message-list-header"
+import MessageTimeline, { buildTimelineSegments, type TimelineSegment } from "./message-timeline"
 import { useConfig } from "../stores/preferences"
 import { getSessionInfo } from "../stores/sessions"
 import { showCommandPalette } from "../stores/command-palette"
@@ -76,14 +77,21 @@ export default function MessageSection(props: MessageSectionProps) {
   const handleCommandPaletteClick = () => {
     showCommandPalette(props.instanceId)
   }
-
+ 
+  const handleTimelineSegmentClick = (segment: TimelineSegment) => {
+    if (typeof document === "undefined") return
+    const anchor = document.getElementById(getMessageAnchorId(segment.messageId))
+    anchor?.scrollIntoView({ block: "start", behavior: "smooth" })
+  }
+ 
   const messageIndexMap = createMemo(() => {
+
     const map = new Map<string, number>()
     const ids = messageIds()
     ids.forEach((id, index) => map.set(id, index))
     return map
   })
-
+ 
   const lastAssistantIndex = createMemo(() => {
     const ids = messageIds()
     const resolvedStore = store()
@@ -95,9 +103,25 @@ export default function MessageSection(props: MessageSectionProps) {
     }
     return -1
   })
-
+ 
+  const timelineSegments = createMemo<TimelineSegment[]>(() => {
+    const ids = messageIds()
+    const resolvedStore = store()
+    const segments: TimelineSegment[] = []
+    ids.forEach((messageId) => {
+      const record = resolvedStore.getMessage(messageId)
+      if (!record) return
+      const built = buildTimelineSegments(props.instanceId, record)
+      segments.push(...built)
+    })
+    return segments
+  })
+ 
+  const hasTimelineSegments = () => timelineSegments().length > 0
+ 
   const changeToken = createMemo(() => String(sessionRevision()))
 
+
   const scrollCache = useScrollCache({
     instanceId: () => props.instanceId,
     sessionId: () => props.sessionId,
@@ -362,76 +386,87 @@ export default function MessageSection(props: MessageSectionProps) {
         forceCompactStatusLayout={props.forceCompactStatusLayout}
       />
 
-      <div class="message-stream" ref={setContainerRef} onScroll={handleScroll}>
-        <div ref={setTopSentinel} aria-hidden="true" style={{ height: "1px" }} />
-        <Show when={!props.loading && messageIds().length === 0}>
-          <div class="empty-state">
-            <div class="empty-state-content">
-              <div class="flex flex-col items-center gap-3 mb-6">
-                <img src={codeNomadLogo} alt="CodeNomad logo" class="h-48 w-auto" loading="lazy" />
-                <h1 class="text-3xl font-semibold text-primary">CodeNomad</h1>
+      <div class={`message-layout${hasTimelineSegments() ? " message-layout--with-timeline" : ""}`}>
+        <div class="message-stream-shell">
+          <div class="message-stream" ref={setContainerRef} onScroll={handleScroll}>
+            <div ref={setTopSentinel} aria-hidden="true" style={{ height: "1px" }} />
+            <Show when={!props.loading && messageIds().length === 0}>
+              <div class="empty-state">
+                <div class="empty-state-content">
+                  <div class="flex flex-col items-center gap-3 mb-6">
+                    <img src={codeNomadLogo} alt="CodeNomad logo" class="h-48 w-auto" loading="lazy" />
+                    <h1 class="text-3xl font-semibold text-primary">CodeNomad</h1>
+                  </div>
+                  <h3>Start a conversation</h3>
+                  <p>Type a message below or open the Command Palette:</p>
+                  <ul>
+                    <li>
+                      <span>Command Palette</span>
+                      <Kbd shortcut="cmd+shift+p" class="ml-2" />
+                    </li>
+                    <li>Ask about your codebase</li>
+                    <li>
+                      Attach files with <code>@</code>
+                    </li>
+                  </ul>
+                </div>
               </div>
-              <h3>Start a conversation</h3>
-              <p>Type a message below or open the Command Palette:</p>
-              <ul>
-                <li>
-                  <span>Command Palette</span>
-                  <Kbd shortcut="cmd+shift+p" class="ml-2" />
-                </li>
-                <li>Ask about your codebase</li>
-                <li>
-                  Attach files with <code>@</code>
-                </li>
-              </ul>
+            </Show>
+ 
+            <Show when={props.loading}>
+              <div class="loading-state">
+                <div class="spinner" />
+                <p>Loading messages...</p>
+              </div>
+            </Show>
+ 
+            <MessageBlockList
+              instanceId={props.instanceId}
+              sessionId={props.sessionId}
+              store={store}
+              messageIds={messageIds}
+              messageIndexMap={messageIndexMap}
+              lastAssistantIndex={lastAssistantIndex}
+              showThinking={() => preferences().showThinkingBlocks}
+              thinkingDefaultExpanded={() => (preferences().thinkingBlocksExpansion ?? "expanded") === "expanded"}
+              showUsageMetrics={showUsagePreference}
+              scrollContainer={scrollElement}
+              loading={props.loading}
+              onRevert={props.onRevert}
+              onFork={props.onFork}
+              onContentRendered={handleContentRendered}
+              setBottomSentinel={setBottomSentinel}
+            />
+          </div>
+ 
+          <Show when={showScrollTopButton() || showScrollBottomButton()}>
+            <div class="message-scroll-button-wrapper">
+              <Show when={showScrollTopButton()}>
+                <button type="button" class="message-scroll-button" onClick={() => scrollToTop()} aria-label="Scroll to first message">
+                  <span class="message-scroll-icon" aria-hidden="true">↑</span>
+                </button>
+              </Show>
+              <Show when={showScrollBottomButton()}>
+                <button
+                  type="button"
+                  class="message-scroll-button"
+                  onClick={() => scrollToBottom()}
+                  aria-label="Scroll to latest message"
+                >
+                  <span class="message-scroll-icon" aria-hidden="true">↓</span>
+                </button>
+              </Show>
             </div>
-          </div>
-        </Show>
-
-        <Show when={props.loading}>
-          <div class="loading-state">
-            <div class="spinner" />
-            <p>Loading messages...</p>
-          </div>
-        </Show>
-
-        <MessageBlockList
-          instanceId={props.instanceId}
-          sessionId={props.sessionId}
-          store={store}
-          messageIds={messageIds}
-          messageIndexMap={messageIndexMap}
-          lastAssistantIndex={lastAssistantIndex}
-          showThinking={() => preferences().showThinkingBlocks}
-          thinkingDefaultExpanded={() => (preferences().thinkingBlocksExpansion ?? "expanded") === "expanded"}
-          showUsageMetrics={showUsagePreference}
-          scrollContainer={scrollElement}
-          loading={props.loading}
-          onRevert={props.onRevert}
-          onFork={props.onFork}
-          onContentRendered={handleContentRendered}
-          setBottomSentinel={setBottomSentinel}
-        />
-      </div>
-
-      <Show when={showScrollTopButton() || showScrollBottomButton()}>
-        <div class="message-scroll-button-wrapper">
-          <Show when={showScrollTopButton()}>
-            <button type="button" class="message-scroll-button" onClick={() => scrollToTop()} aria-label="Scroll to first message">
-              <span class="message-scroll-icon" aria-hidden="true">↑</span>
-            </button>
-          </Show>
-          <Show when={showScrollBottomButton()}>
-            <button
-              type="button"
-              class="message-scroll-button"
-              onClick={() => scrollToBottom()}
-              aria-label="Scroll to latest message"
-            >
-              <span class="message-scroll-icon" aria-hidden="true">↓</span>
-            </button>
           </Show>
         </div>
-      </Show>
+ 
+        <Show when={hasTimelineSegments()}>
+          <div class="message-timeline-sidebar">
+            <MessageTimeline segments={timelineSegments()} onSegmentClick={handleTimelineSegmentClick} />
+          </div>
+        </Show>
+      </div>
+
     </div>
   )
 }
diff --git a/packages/ui/src/components/message-timeline.tsx b/packages/ui/src/components/message-timeline.tsx
new file mode 100644
index 00000000..2e55aa6b
--- /dev/null
+++ b/packages/ui/src/components/message-timeline.tsx
@@ -0,0 +1,224 @@
+import { For, type Component } from "solid-js"
+import type { ClientPart } from "../types/message"
+import type { MessageRecord } from "../stores/message-v2/types"
+import { buildRecordDisplayData } from "../stores/message-v2/record-display-cache"
+
+export type TimelineSegmentType = "user" | "assistant" | "tool"
+
+export interface TimelineSegment {
+  id: string
+  messageId: string
+  type: TimelineSegmentType
+  label: string
+  tooltip: string
+}
+
+interface MessageTimelineProps {
+  segments: TimelineSegment[]
+  onSegmentClick?: (segment: TimelineSegment) => void
+}
+
+const SEGMENT_LABELS: Record<TimelineSegmentType, string> = {
+  user: "User",
+  assistant: "Asst",
+  tool: "Tool",
+}
+
+const SEGMENT_SHORT_LABELS: Record<TimelineSegmentType, string> = {
+  user: "U",
+  assistant: "A",
+  tool: "T",
+}
+
+const TOOL_FALLBACK_LABEL = "Tool Call"
+const MAX_TOOLTIP_LENGTH = 220
+
+type ToolCallPart = Extract<ClientPart, { type: "tool" }>
+
+interface PendingSegment {
+  type: TimelineSegmentType
+  texts: string[]
+  toolTitles: string[]
+}
+
+function truncateText(value: string): string {
+  if (value.length <= MAX_TOOLTIP_LENGTH) {
+    return value
+  }
+  return `${value.slice(0, MAX_TOOLTIP_LENGTH - 1).trimEnd()}…`
+}
+
+function collectReasoningText(part: ClientPart): string {
+  const stringifySegment = (segment: unknown): string => {
+    if (typeof segment === "string") {
+      return segment
+    }
+    if (segment && typeof segment === "object") {
+      const obj = segment as { text?: unknown; value?: unknown; content?: unknown[] }
+      const parts: string[] = []
+      if (typeof obj.text === "string") {
+        parts.push(obj.text)
+      }
+      if (typeof obj.value === "string") {
+        parts.push(obj.value)
+      }
+      if (Array.isArray(obj.content)) {
+        parts.push(obj.content.map((entry) => stringifySegment(entry)).join("\n"))
+      }
+      return parts.filter(Boolean).join("\n")
+    }
+    return ""
+  }
+
+  if (typeof (part as any)?.text === "string") {
+    return (part as any).text
+  }
+  if (Array.isArray((part as any)?.content)) {
+    return (part as any).content.map((entry: unknown) => stringifySegment(entry)).join("\n")
+  }
+  return ""
+}
+
+function collectTextFromPart(part: ClientPart): string {
+  if (!part) return ""
+  if (typeof (part as any).text === "string") {
+    return (part as any).text as string
+  }
+  if (part.type === "reasoning") {
+    return collectReasoningText(part)
+  }
+  if (Array.isArray((part as any)?.content)) {
+    return ((part as any).content as unknown[])
+      .map((entry) => (typeof entry === "string" ? entry : ""))
+      .filter(Boolean)
+      .join("\n")
+  }
+  if (part.type === "file") {
+    const filename = (part as any)?.filename
+    return typeof filename === "string" && filename.length > 0 ? `[File] ${filename}` : "Attachment"
+  }
+  return ""
+}
+
+function getToolTitle(part: ToolCallPart): string {
+  const metadata = (((part as unknown as { state?: { metadata?: unknown } })?.state?.metadata) || {}) as { title?: unknown }
+  const title = typeof metadata.title === "string" && metadata.title.length > 0 ? metadata.title : undefined
+  if (title) return title
+  if (typeof part.tool === "string" && part.tool.length > 0) {
+    return part.tool
+  }
+  return TOOL_FALLBACK_LABEL
+}
+
+function formatTextsTooltip(texts: string[], fallback: string): string {
+  const combined = texts
+    .map((text) => text.trim())
+    .filter((text) => text.length > 0)
+    .join("\n\n")
+  if (combined.length > 0) {
+    return truncateText(combined)
+  }
+  return fallback
+}
+
+function formatToolTooltip(titles: string[]): string {
+  if (titles.length === 0) {
+    return TOOL_FALLBACK_LABEL
+  }
+  return truncateText(`${TOOL_FALLBACK_LABEL}: ${titles.join(", ")}`)
+}
+
+export function buildTimelineSegments(instanceId: string, record: MessageRecord): TimelineSegment[] {
+  if (!record) return []
+  const { orderedParts } = buildRecordDisplayData(instanceId, record)
+  if (!orderedParts || orderedParts.length === 0) {
+    return []
+  }
+
+  const result: TimelineSegment[] = []
+  let segmentIndex = 0
+  let pending: PendingSegment | null = null
+
+  const flushPending = () => {
+    if (!pending) return
+    const label = SEGMENT_LABELS[pending.type]
+    const tooltip = pending.type === "tool"
+      ? formatToolTooltip(pending.toolTitles)
+      : formatTextsTooltip(
+          pending.texts,
+          pending.type === "user" ? "User message" : "Assistant response",
+        )
+
+    result.push({
+      id: `${record.id}:${segmentIndex}`,
+      messageId: record.id,
+      type: pending.type,
+      label,
+      tooltip,
+    })
+    segmentIndex += 1
+    pending = null
+  }
+
+  const ensureSegment = (type: TimelineSegmentType) => {
+    if (!pending || pending.type !== type) {
+      flushPending()
+      pending = { type, texts: [], toolTitles: [] }
+    }
+    return pending
+  }
+
+  const defaultContentType: TimelineSegmentType = record.role === "user" ? "user" : "assistant"
+
+  for (const part of orderedParts) {
+    if (!part || typeof part !== "object") continue
+
+    if (part.type === "tool") {
+      const target = ensureSegment("tool")
+      target.toolTitles.push(getToolTitle(part as ToolCallPart))
+      continue
+    }
+
+    if (part.type === "reasoning") {
+      const text = collectReasoningText(part)
+      if (text.trim().length === 0) continue
+      const target = ensureSegment(defaultContentType)
+      target.texts.push(text)
+      continue
+    }
+
+    if (part.type === "step-start" || part.type === "step-finish") {
+      continue
+    }
+
+    const text = collectTextFromPart(part)
+    if (text.trim().length === 0) continue
+    const target = ensureSegment(defaultContentType)
+    target.texts.push(text)
+  }
+
+  flushPending()
+  return result
+}
+
+const MessageTimeline: Component<MessageTimelineProps> = (props) => {
+  return (
+    <div class="message-timeline" role="navigation" aria-label="Message timeline">
+      <For each={props.segments}>
+        {(segment) => (
+          <button
+            type="button"
+            class={`message-timeline-segment message-timeline-${segment.type}`}
+            title={segment.tooltip}
+            onClick={() => props.onSegmentClick?.(segment)}
+          >
+            <span class="message-timeline-label message-timeline-label-full">{segment.label}</span>
+            <span class="message-timeline-label message-timeline-label-short">{SEGMENT_SHORT_LABELS[segment.type]}</span>
+          </button>
+        )}
+      </For>
+    </div>
+  )
+}
+
+export default MessageTimeline
diff --git a/packages/ui/src/components/virtual-item.tsx b/packages/ui/src/components/virtual-item.tsx
index adef877a..6612bc20 100644
--- a/packages/ui/src/components/virtual-item.tsx
+++ b/packages/ui/src/components/virtual-item.tsx
@@ -99,6 +99,7 @@ interface VirtualItemProps {
   virtualizationEnabled?: Accessor<boolean>
   forceVisible?: Accessor<boolean>
   onMeasured?: () => void
+  id?: string
 }
 
 export default function VirtualItem(props: VirtualItemProps) {
@@ -268,7 +269,7 @@ export default function VirtualItem(props: VirtualItemProps) {
   const placeholderClass = () => ["virtual-item-placeholder", props.placeholderClass].filter(Boolean).join(" ")
  
   return (
-    <div ref={setWrapperRef} class={wrapperClass()} style={{ width: "100%" }}>
+    <div ref={setWrapperRef} id={props.id} class={wrapperClass()} style={{ width: "100%" }}>
       <div
         class={placeholderClass()}
         style={{
diff --git a/packages/ui/src/styles/messaging.css b/packages/ui/src/styles/messaging.css
index 62ea7b25..2ed011e4 100644
--- a/packages/ui/src/styles/messaging.css
+++ b/packages/ui/src/styles/messaging.css
@@ -2,6 +2,7 @@
 @import "./messaging/prompt-input.css";
 @import "./messaging/message-section.css";
 @import "./messaging/message-block-list.css";
+@import "./messaging/message-timeline.css";
 @import "./messaging/tool-call.css";
 @import "./messaging/log-view.css";
 
diff --git a/packages/ui/src/styles/messaging/message-timeline.css b/packages/ui/src/styles/messaging/message-timeline.css
new file mode 100644
index 00000000..4fe7ed00
--- /dev/null
+++ b/packages/ui/src/styles/messaging/message-timeline.css
@@ -0,0 +1,127 @@
+.message-layout {
+  display: grid;
+  grid-template-columns: minmax(0, 1fr);
+  gap: 0.5rem;
+  width: 100%;
+  min-height: 0;
+  flex: 1 1 auto;
+}
+
+.message-layout--with-timeline {
+  grid-template-columns: minmax(0, 1fr) 64px;
+}
+
+@media (max-width: 720px) {
+  .message-layout--with-timeline {
+    grid-template-columns: minmax(0, 1fr) 40px;
+  }
+}
+
+.message-stream-shell {
+  min-height: 0;
+  display: flex;
+  flex-direction: column;
+  position: relative;
+}
+
+.message-stream-shell .message-stream {
+  flex: 1 1 auto;
+  min-height: 0;
+}
+
+.message-timeline-sidebar {
+  width: 64px;
+  min-height: 0;
+  display: flex;
+  flex-direction: column;
+}
+
+@media (max-width: 720px) {
+  .message-timeline-sidebar {
+    width: 40px;
+  }
+}
+
+.message-timeline {
+  flex: 1 1 auto;
+  display: flex;
+  flex-direction: column;
+  gap: 0.35rem;
+  padding: 0.25rem;
+  overflow-y: auto;
+  border-radius: 8px;
+  background-color: var(--surface-base);
+  box-shadow: var(--panel-shadow, 0 6px 24px rgba(0, 0, 0, 0.2));
+}
+
+.message-timeline::-webkit-scrollbar {
+  width: 5px;
+}
+
+.message-timeline::-webkit-scrollbar-thumb {
+  background-color: var(--border-muted);
+  border-radius: 9999px;
+}
+
+.message-timeline-segment {
+  width: 100%;
+  min-height: 1.5rem;
+  border-radius: 0;
+  border: 1px solid var(--border-base);
+  background-color: var(--surface-secondary);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  font-size: 0.65rem;
+  font-weight: 600;
+  letter-spacing: 0.05em;
+  text-transform: uppercase;
+  color: var(--text-primary);
+  transition: transform 0.15s ease, background-color 0.2s ease, color 0.2s ease;
+}
+
+.message-timeline-segment:hover,
+.message-timeline-segment:focus-visible {
+  background-color: var(--surface-hover);
+  color: var(--accent-primary);
+  outline: none;
+  transform: translateY(-1px);
+}
+
+.message-timeline-segment:focus-visible {
+  box-shadow: 0 0 0 2px var(--surface-base), 0 0 0 4px var(--accent-primary);
+}
+
+.message-timeline-user {
+  border-color: var(--message-user-border);
+  background-color: var(--message-user-bg);
+}
+
+.message-timeline-assistant {
+  border-color: var(--message-assistant-border);
+  background-color: var(--message-assistant-bg);
+}
+
+.message-timeline-tool {
+  border-color: var(--message-tool-border);
+  background-color: var(--surface-secondary);
+}
+
+.message-timeline-label {
+  pointer-events: none;
+}
+
+.message-timeline-label-short {
+  display: none;
+}
+
+@media (max-width: 720px) {
+  .message-timeline-label-full {
+    display: none;
+  }
+  .message-timeline-label-short {
+    display: block;
+  }
+}
+
+