diff --git a/src/renderer/src/components/native-chat/NativeChatMessageRow.tsx b/src/renderer/src/components/native-chat/NativeChatMessageRow.tsx
index 97fc3091299..087a147e3f9 100644
--- a/src/renderer/src/components/native-chat/NativeChatMessageRow.tsx
+++ b/src/renderer/src/components/native-chat/NativeChatMessageRow.tsx
@@ -153,6 +153,8 @@ export const MessageRow = memo(function MessageRow({
     return (
       <div ref={rowRef}>
         <NativeChatReasoningRow
+          blockId={message.id}
+          isStreaming={activeTurnIsWorking}
           markdown={markdown}
           onLinkClick={onLinkClick}
           allowFileUriLinks={allowFileUriLinks}
diff --git a/src/renderer/src/components/native-chat/NativeChatReasoningRow.test.tsx b/src/renderer/src/components/native-chat/NativeChatReasoningRow.test.tsx
index 77c8f5e38da..fe59a95b546 100644
--- a/src/renderer/src/components/native-chat/NativeChatReasoningRow.test.tsx
+++ b/src/renderer/src/components/native-chat/NativeChatReasoningRow.test.tsx
@@ -10,16 +10,19 @@ vi.mock('@/components/sidebar/CommentMarkdown', () => ({
   default: ({ content }: { content: string }) => <div data-testid="markdown">{content}</div>
 }))
 
-afterEach(cleanup)
+afterEach(() => {
+  cleanup()
+  vi.restoreAllMocks()
+})
 
 describe('reasoning disclosure', () => {
-  it('starts collapsed with the first meaningful line and does not mount markdown', () => {
+  it('shows the unobserved-history fallback collapsed without mounting markdown', () => {
     render(<NativeChatReasoningRow markdown={'\n\nInspecting the request\nFull reasoning'} />)
     expect(
-      screen.getByRole('button', { name: 'Reasoning: Inspecting the request' })
+      screen.getByRole('button', { name: 'Reasoning: Thought for a few seconds' })
     ).toHaveAttribute('aria-expanded', 'false')
     expect(screen.queryByTestId('markdown')).not.toBeInTheDocument()
-    expect(screen.queryByText(/Thought for/)).not.toBeInTheDocument()
+    expect(screen.getByRole('button')).not.toHaveTextContent(/\d/)
   })
 
   it('expands through a native button and preserves disclosure state through revisions', () => {
@@ -44,10 +47,46 @@ describe('reasoning disclosure', () => {
     expect(container).toBeEmptyDOMElement()
   })
 
-  it('bounds a growing summary without changing the collapsed layout', () => {
-    render(<NativeChatReasoningRow markdown={'a'.repeat(200)} />)
-    expect(screen.getByRole('button')).toHaveTextContent(`${'a'.repeat(120)}…`)
+  it('shows Thinking while streaming and freezes the locally observed duration on settlement', () => {
+    const now = vi.spyOn(Date, 'now').mockReturnValue(100_000)
+    const { rerender } = render(
+      <NativeChatReasoningRow blockId="a" markdown="Inspecting" isStreaming />
+    )
+    expect(screen.getByRole('button')).toHaveTextContent('Thinking...')
+    expect(screen.getByText('Thinking...')).toHaveClass('animate-pulse')
+    now.mockReturnValue(105_000)
+    rerender(<NativeChatReasoningRow blockId="a" markdown="Inspecting more" isStreaming />)
+    now.mockReturnValue(112_000)
+    rerender(<NativeChatReasoningRow blockId="a" markdown="Done" isStreaming={false} />)
+    expect(screen.getByRole('button')).toHaveTextContent('Thought for 12s')
+    now.mockReturnValue(180_000)
+    rerender(<NativeChatReasoningRow blockId="a" markdown="Done again" />)
+    expect(screen.getByRole('button')).toHaveTextContent('Thought for 12s')
     expect(screen.queryByTestId('markdown')).not.toBeInTheDocument()
+    rerender(<NativeChatReasoningRow blockId="history" markdown="Replayed" />)
+    expect(screen.getByRole('button')).toHaveTextContent('Thought for a few seconds')
+    expect(screen.getByRole('button')).not.toHaveTextContent(/\d/)
+    rerender(<NativeChatReasoningRow blockId="b" markdown="New block" isStreaming />)
+    now.mockReturnValue(245_000)
+    rerender(<NativeChatReasoningRow blockId="b" markdown="New block done" />)
+    expect(screen.getByRole('button')).toHaveTextContent('Thought for 1m 5s')
+  })
+
+  it('resets the clock when block identity changes without a streaming-state transition', () => {
+    const now = vi.spyOn(Date, 'now').mockReturnValue(10_000)
+    const { rerender } = render(<NativeChatReasoningRow blockId="a" markdown="First" isStreaming />)
+    now.mockReturnValue(30_000)
+    rerender(<NativeChatReasoningRow blockId="b" markdown="Second" isStreaming />)
+    now.mockReturnValue(33_000)
+    rerender(<NativeChatReasoningRow blockId="b" markdown="Second done" />)
+    expect(screen.getByRole('button')).toHaveTextContent('Thought for 3s')
+  })
+
+  it('never displays zero seconds for a briefly observed stream', () => {
+    vi.spyOn(Date, 'now').mockReturnValue(100_000)
+    const { rerender } = render(<NativeChatReasoningRow markdown="Brief" isStreaming />)
+    rerender(<NativeChatReasoningRow markdown="Brief" />)
+    expect(screen.getByRole('button')).toHaveTextContent('Thought for 1s')
   })
 
   it('uses the existing message prose pipeline for reasoning-role messages', () => {
@@ -58,7 +97,24 @@ describe('reasoning disclosure', () => {
       timestamp: 1,
       blocks: [{ type: 'text', text: 'Inspecting the request\nFull reasoning' }]
     }
-    render(<MessageRow message={message} expandSignal={false} onScrollMessageToTop={vi.fn()} />)
+    const { rerender } = render(
+      <MessageRow
+        message={message}
+        activeTurnIsWorking
+        expandSignal={false}
+        onScrollMessageToTop={vi.fn()}
+      />
+    )
+    expect(screen.getByRole('button')).toHaveTextContent('Thinking...')
+    rerender(
+      <MessageRow
+        message={{ ...message, id: 'history', timestamp: 1 }}
+        activeTurnIsWorking={false}
+        expandSignal={false}
+        onScrollMessageToTop={vi.fn()}
+      />
+    )
+    expect(screen.getByRole('button')).toHaveTextContent('Thought for a few seconds')
     fireEvent.click(screen.getByRole('button'))
     expect(screen.getByTestId('markdown')).toHaveTextContent('Full reasoning')
   })
diff --git a/src/renderer/src/components/native-chat/NativeChatReasoningRow.tsx b/src/renderer/src/components/native-chat/NativeChatReasoningRow.tsx
index 1778305c1af..1ed9f02120e 100644
--- a/src/renderer/src/components/native-chat/NativeChatReasoningRow.tsx
+++ b/src/renderer/src/components/native-chat/NativeChatReasoningRow.tsx
@@ -1,32 +1,81 @@
+import { useEffect, useState } from 'react'
 import { ChevronRight } from 'lucide-react'
 import CommentMarkdown, {
   type CommentMarkdownLinkClickHandler
 } from '@/components/sidebar/CommentMarkdown'
 import { Collapsible, CollapsibleContent, CollapsibleTrigger } from '@/components/ui/collapsible'
 import { translate } from '@/i18n/i18n'
+import { formatNativeChatDuration } from '../../../../shared/native-chat-turn-status'
 
 export function NativeChatReasoningRow({
   markdown,
+  isStreaming = false,
+  blockId = 'default',
   onLinkClick,
   allowFileUriLinks
 }: {
   markdown: string
+  isStreaming?: boolean
+  blockId?: string
   onLinkClick?: CommentMarkdownLinkClickHandler
   allowFileUriLinks?: boolean
 }): React.JSX.Element | null {
-  const firstLine = markdown.trim().split('\n', 1)[0]?.trim()
-  if (!firstLine) {
+  const [timing, setTiming] = useState(() => ({
+    blockId,
+    streaming: isStreaming,
+    startedAt: isStreaming ? Date.now() : null,
+    elapsedMs: null as number | null
+  }))
+  useEffect(() => {
+    const now = Date.now()
+    setTiming((previous) => {
+      if (previous.blockId !== blockId) {
+        return {
+          blockId,
+          streaming: isStreaming,
+          startedAt: isStreaming ? now : null,
+          elapsedMs: null
+        }
+      }
+      if (previous.streaming === isStreaming) {
+        return previous
+      }
+      // Only an observed stream supplies a duration; journal history has no local start.
+      return {
+        ...previous,
+        streaming: isStreaming,
+        startedAt: isStreaming ? now : previous.startedAt,
+        elapsedMs: isStreaming || previous.startedAt === null ? null : now - previous.startedAt
+      }
+    })
+  }, [blockId, isStreaming])
+  if (!markdown.trim()) {
     return null
   }
-  const summary = firstLine.length > 120 ? `${firstLine.slice(0, 120)}…` : firstLine
   const label = translate('components.native-chat.reasoning', 'Reasoning')
+  const duration = timing.blockId === blockId ? timing.elapsedMs : null
+  const headline = isStreaming
+    ? translate('components.native-chat.thinking', 'Thinking...')
+    : duration === null
+      ? translate('components.native-chat.thoughtForFewSeconds', 'Thought for a few seconds')
+      : translate('components.native-chat.thoughtForDuration', 'Thought for {{duration}}', {
+          duration: formatNativeChatDuration(Math.max(1, duration / 1000))
+        })
 
   return (
     <Collapsible className="min-w-0 text-sm text-muted-foreground">
-      <CollapsibleTrigger className="group flex w-full min-w-0 items-center gap-1.5 rounded-sm py-1 text-left hover:text-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring">
+      <CollapsibleTrigger className="group flex w-full min-w-0 items-center gap-1.5 rounded-sm py-1 text-left text-[13px] hover:text-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring">
         <span className="sr-only">{label}: </span>
-        <span className="min-w-0 flex-1 truncate">{summary}</span>
-        <ChevronRight className="size-3.5 shrink-0 transition-transform group-data-[state=open]:rotate-90 motion-reduce:transition-none" />
+        <span
+          className={
+            isStreaming
+              ? 'min-w-0 truncate animate-pulse motion-reduce:animate-none'
+              : 'min-w-0 truncate'
+          }
+        >
+          {headline}
+        </span>
+        <ChevronRight className="ml-auto size-3.5 shrink-0 transition-transform group-data-[state=open]:rotate-90 motion-reduce:transition-none" />
       </CollapsibleTrigger>
       <CollapsibleContent className="pt-1 pl-4 italic">
         <CommentMarkdown
diff --git a/src/renderer/src/i18n/locales/en.json b/src/renderer/src/i18n/locales/en.json
index e6481e66813..da69adeed16 100644
--- a/src/renderer/src/i18n/locales/en.json
+++ b/src/renderer/src/i18n/locales/en.json
@@ -17192,7 +17192,10 @@
       "conversationCommand": {
         "pendingWork": "Wait for pending work and messages to finish before using this command.",
         "unconfirmed": "Conversation operation was not confirmed."
-      }
+      },
+      "thinking": "Thinking...",
+      "thoughtForFewSeconds": "Thought for a few seconds",
+      "thoughtForDuration": "Thought for {{duration}}"
     },
     "tab": {
       "bar": {