diff --git a/desktop/src/components/chat/ThinkingBlock.tsx b/desktop/src/components/chat/ThinkingBlock.tsx
index d43889b4..284f9a3f 100644
--- a/desktop/src/components/chat/ThinkingBlock.tsx
+++ b/desktop/src/components/chat/ThinkingBlock.tsx
@@ -2,20 +2,12 @@ import { useState, useEffect, useMemo, useRef } from 'react'
 import { useTranslation } from '../../i18n'
 import { MarkdownRenderer } from '../markdown/MarkdownRenderer'
 
-const PREVIEW_LINE_LIMIT = 10
-
 export function ThinkingBlock({ content, isActive = false }: { content: string; isActive?: boolean }) {
   const t = useTranslation()
   const [expanded, setExpanded] = useState(false)
   const contentRef = useRef<HTMLDivElement>(null)
   const displayContent = useMemo(() => content.replace(/\r\n?/g, '\n').trimEnd(), [content])
   const hasDisplayContent = displayContent.trim().length > 0
-  const displayLines = useMemo(() => displayContent.split('\n'), [displayContent])
-  const previewContent = useMemo(
-    () => displayLines.slice(0, PREVIEW_LINE_LIMIT).join('\n'),
-    [displayLines],
-  )
-  const isPreviewTruncated = displayLines.length > PREVIEW_LINE_LIMIT
 
   useEffect(() => {
     if (expanded && isActive && contentRef.current) {
@@ -40,29 +32,20 @@ export function ThinkingBlock({ content, isActive = false }: { content: string;
           {isActive && <span className="thinking-dots" />}
         </span>
       </button>
-      {hasDisplayContent && (
+      {expanded && hasDisplayContent && (
         <div
-          ref={expanded ? contentRef : undefined}
-          data-thinking-content={expanded ? 'expanded' : 'collapsed'}
-          data-thinking-truncated={!expanded && isPreviewTruncated ? 'true' : undefined}
-          onClick={!expanded ? () => setExpanded(true) : undefined}
-          className={`relative mt-1 rounded-lg border border-[var(--color-border)]/40 bg-[var(--color-surface-container-lowest)] p-2.5 text-[11px] text-[var(--color-text-secondary)] ${
-            expanded
-              ? 'max-h-[300px] overflow-y-auto'
-              : 'thinking-preview-clamp cursor-pointer'
-          }`}
+          ref={contentRef}
+          data-thinking-content="expanded"
+          className="relative mt-1 max-h-[300px] overflow-y-auto rounded-lg border border-[var(--color-border)]/40 bg-[var(--color-surface-container-lowest)] p-2.5 text-[11px] text-[var(--color-text-secondary)]"
         >
           <MarkdownRenderer
-            content={expanded ? displayContent : previewContent}
+            content={displayContent}
             variant="compact"
             cache={!isActive}
             streaming={isActive}
             className="thinking-markdown text-[var(--color-text-secondary)]"
           />
-          {!expanded && isPreviewTruncated && <span className="thinking-preview-fade" aria-hidden="true" />}
-          {isActive && (
-            <span className={expanded ? 'thinking-cursor' : 'thinking-inline-cursor thinking-preview-active-cursor'} />
-          )}
+          {isActive && <span className="thinking-cursor" />}
         </div>
       )}
     </div>
@@ -89,15 +72,6 @@ const thinkingStyles = `
   margin-left: 1px;
   animation: thinking-cursor-blink 1s step-end infinite;
 }
-.thinking-inline-cursor {
-  display: inline-block;
-  width: 1px;
-  height: 0.95em;
-  margin-left: 3px;
-  vertical-align: text-bottom;
-  background: var(--color-text-tertiary);
-  animation: thinking-cursor-blink 1s step-end infinite;
-}
 .thinking-dots::after {
   content: '';
   animation: thinking-dots 1.4s steps(1, end) infinite;
@@ -110,24 +84,4 @@ const thinkingStyles = `
 .thinking-markdown > :last-child > :last-child {
   margin-bottom: 0;
 }
-.thinking-preview-clamp {
-  max-height: calc(${PREVIEW_LINE_LIMIT} * 1.25rem + 1.25rem);
-  overflow: hidden;
-}
-.thinking-preview-fade {
-  position: absolute;
-  left: 0;
-  right: 0;
-  bottom: 0;
-  height: 1.75rem;
-  border-bottom-left-radius: 0.5rem;
-  border-bottom-right-radius: 0.5rem;
-  pointer-events: none;
-  background: linear-gradient(to bottom, transparent, var(--color-surface-container-lowest));
-}
-.thinking-preview-active-cursor {
-  position: absolute;
-  right: 0.6rem;
-  bottom: 0.45rem;
-}
 `
diff --git a/desktop/src/components/chat/chatBlocks.test.tsx b/desktop/src/components/chat/chatBlocks.test.tsx
index 22985b67..25e41d3c 100644
--- a/desktop/src/components/chat/chatBlocks.test.tsx
+++ b/desktop/src/components/chat/chatBlocks.test.tsx
@@ -18,32 +18,42 @@ describe('chat blocks', () => {
     const { container } = render(<ThinkingBlock content="this is a long internal reasoning trace" isActive />)
 
     expect(screen.getByText(/Thinking/)).toBeTruthy()
-    expect(container.textContent).toContain('this is a long internal reasoning trace')
+    expect(container.textContent).not.toContain('this is a long internal reasoning trace')
     expect(container.querySelector('.thinking-cursor')).toBeNull()
   })
 
   it('does not animate inactive historical thinking blocks', () => {
     const { container } = render(<ThinkingBlock content="old reasoning" isActive={false} />)
 
-    expect(container.querySelector('.thinking-inline-cursor')).toBeNull()
+    fireEvent.click(screen.getByRole('button', { name: /Thinking/ }))
+
+    expect(container.textContent).toContain('old reasoning')
+    expect(container.querySelector('.thinking-cursor')).toBeNull()
   })
 
-  it('renders collapsed thinking content as markdown', () => {
+  it('renders thinking content as markdown only after expanding', () => {
     const { container } = render(<ThinkingBlock content={'**important**\n\n- item one'} />)
 
+    expect(container.textContent).not.toContain('important')
+    expect(container.querySelector('strong')).toBeNull()
+    expect(container.querySelector('li')).toBeNull()
+
+    fireEvent.click(screen.getByRole('button', { name: /Thinking/ }))
+
     expect(container.querySelector('strong')?.textContent).toBe('important')
     expect(container.querySelector('li')?.textContent).toBe('item one')
   })
 
-  it('limits collapsed thinking content to ten lines until expanded', () => {
+  it('hides full thinking content until expanded', () => {
     const content = Array.from({ length: 12 }, (_, index) => `line-${index + 1}`).join('\n')
     const { container } = render(<ThinkingBlock content={content} />)
 
-    expect(container.textContent).toContain('line-10')
+    expect(container.textContent).not.toContain('line-1')
     expect(container.textContent).not.toContain('line-11')
 
     fireEvent.click(screen.getByRole('button', { name: /Thinking/ }))
 
+    expect(container.textContent).toContain('line-1')
     expect(container.textContent).toContain('line-11')
     expect(container.textContent).toContain('line-12')
   })