fix: keep historical thinking collapsed in tui

(cherry picked from commit 354999388a4e465b6b7efa46cdc61d8d5b22b35f)

ui-tui/src/__tests__/messages.test.ts

@@ -128,6 +128,81 @@ describe('MessageLine', () => {
 
     expect(renderedLine).toContain('Ψ > Okay')
   })
+
+  it('keeps historical thinking blocks collapsed by default', () => {
+    const stdout = new PassThrough()
+    const stdin = new PassThrough()
+    const stderr = new PassThrough()
+    let output = ''
+
+    Object.assign(stdout, { columns: 80, isTTY: false, rows: 24 })
+    Object.assign(stdin, { isTTY: false })
+    Object.assign(stderr, { isTTY: false })
+    stdout.on('data', chunk => {
+      output += chunk.toString()
+    })
+
+    const instance = renderSync(
+      React.createElement(MessageLine, {
+        cols: 80,
+        msg: { kind: 'trail', role: 'system', text: '', thinking: 'step one\nstep two' },
+        t: DEFAULT_THEME
+      }),
+      {
+        patchConsole: false,
+        stderr: stderr as NodeJS.WriteStream,
+        stdin: stdin as NodeJS.ReadStream,
+        stdout: stdout as NodeJS.WriteStream
+      }
+    )
+
+    instance.unmount()
+    instance.cleanup()
+
+    const rendered = stripAnsi(output)
+
+    expect(rendered).toContain('Thinking')
+    expect(rendered).not.toContain('step one')
+    expect(rendered).not.toContain('step two')
+  })
+
+  it('keeps live thinking blocks expanded while streaming', () => {
+    const stdout = new PassThrough()
+    const stdin = new PassThrough()
+    const stderr = new PassThrough()
+    let output = ''
+
+    Object.assign(stdout, { columns: 80, isTTY: false, rows: 24 })
+    Object.assign(stdin, { isTTY: false })
+    Object.assign(stderr, { isTTY: false })
+    stdout.on('data', chunk => {
+      output += chunk.toString()
+    })
+
+    const instance = renderSync(
+      React.createElement(MessageLine, {
+        cols: 80,
+        liveDetails: true,
+        msg: { kind: 'trail', role: 'system', text: '', thinking: 'step one\nstep two' },
+        t: DEFAULT_THEME
+      }),
+      {
+        patchConsole: false,
+        stderr: stderr as NodeJS.WriteStream,
+        stdin: stdin as NodeJS.ReadStream,
+        stdout: stdout as NodeJS.WriteStream
+      }
+    )
+
+    instance.unmount()
+    instance.cleanup()
+
+    const rendered = stripAnsi(output)
+
+    expect(rendered).toContain('Thinking')
+    expect(rendered).toContain('step one')
+    expect(rendered).toContain('step two')
+  })
 })
 
 describe('upsert', () => {

ui-tui/src/__tests__/virtualHeights.test.ts

@@ -82,6 +82,28 @@ describe('virtual height estimates', () => {
     ).toBe(estimatedMsgHeight(toolsOnly, 80, { compact: false, details: false }))
   })
 
+  it('treats historical thinking blocks as collapsed unless explicitly expanded', () => {
+    const msg: Msg = { role: 'assistant', text: 'ok', thinking: 'line 1\nline 2\nline 3' }
+
+    expect(
+      estimatedMsgHeight(msg, 80, {
+        compact: false,
+        details: true,
+        thinkingExpanded: false,
+        thinkingVisible: true,
+        toolsVisible: false
+      })
+    ).toBeLessThan(
+      estimatedMsgHeight(msg, 80, {
+        compact: false,
+        details: true,
+        thinkingExpanded: true,
+        thinkingVisible: true,
+        toolsVisible: false
+      })
+    )
+  })
+
   it('reserves two extra rows for the inter-turn separator on non-first user messages', () => {
     const msg: Msg = { role: 'user', text: 'follow-up question' }
     const base = estimatedMsgHeight(msg, 80, { compact: false, details: false })

ui-tui/src/app/useMainApp.ts

@@ -353,6 +353,10 @@ export function useMainApp(gw: GatewayClient) {
   const [thinkingDetailsMode, toolsDetailsMode] = detailsLayoutKey.split(':')
   const thinkingDetailsVisible = thinkingDetailsMode !== 'hidden'
   const toolsDetailsVisible = toolsDetailsMode !== 'hidden'
+
+  const historyThinkingExpanded =
+    thinkingDetailsVisible && (ui.detailsModeCommandOverride || ui.sections.thinking === 'expanded')
+
   const detailsVisible = thinkingDetailsVisible || toolsDetailsVisible
   const userPromptWidth = composerPromptWidth(ui.theme.brand.prompt)
   const heightCacheKey = `${ui.sid ?? 'draft'}:${cols}:${userPromptWidth}:${ui.compact ? '1' : '0'}:${detailsLayoutKey}`
@@ -390,6 +394,7 @@ export function useMainApp(gw: GatewayClient) {
           }),
           virtualRows[index]!.msg
         ),
+        thinkingExpanded: historyThinkingExpanded,
         thinkingVisible: thinkingDetailsVisible,
         toolsVisible: toolsDetailsVisible,
         userPrompt: ui.theme.brand.prompt,
@@ -399,6 +404,7 @@ export function useMainApp(gw: GatewayClient) {
       cols,
       detailsVisible,
       firstUserIdx,
+      historyThinkingExpanded,
       thinkingDetailsVisible,
       toolsDetailsVisible,
       ui.compact,

ui-tui/src/components/messageLine.tsx

@@ -34,6 +34,7 @@ export const MessageLine = memo(function MessageLine({
   detailsMode = 'collapsed',
   detailsModeCommandOverride = false,
   isStreaming = false,
+  liveDetails = false,
   msg,
   prev,
   sections,
@@ -81,6 +82,7 @@ export const MessageLine = memo(function MessageLine({
         <ToolTrail
           commandOverride={detailsModeCommandOverride}
           detailsMode={detailsMode}
+          preferExpandedThinking={liveDetails}
           reasoning={thinking}
           reasoningAlwaysVisible={msg.isMoaReference}
           reasoningTokens={msg.thinkingTokens}
@@ -245,6 +247,7 @@ export const MessageLine = memo(function MessageLine({
           <ToolTrail
             commandOverride={detailsModeCommandOverride}
             detailsMode={detailsMode}
+            preferExpandedThinking={liveDetails}
             reasoning={thinking}
             reasoningTokens={msg.thinkingTokens}
             sections={sections}
@@ -300,6 +303,7 @@ interface MessageLineProps {
   detailsMode?: DetailsMode
   detailsModeCommandOverride?: boolean
   isStreaming?: boolean
+  liveDetails?: boolean
   msg: Msg
   // The block rendered directly above this one. Drives the group-boundary
   // lead gap (see domain/blockLayout.ts::hasLeadGap). Undefined at the top of

ui-tui/src/components/streamingAssistant.tsx

@@ -76,6 +76,7 @@ export const StreamingAssistant = memo(function StreamingAssistant({
             detailsModeCommandOverride={detailsModeCommandOverride}
             isStreaming={block.isStreaming}
             key={block.key}
+            liveDetails
             msg={block.msg}
             prev={prev}
             sections={sections}

ui-tui/src/components/thinking.tsx

@@ -678,6 +678,7 @@ export const ToolTrail = memo(function ToolTrail({
   commandOverride = false,
   detailsMode = 'collapsed',
   outcome = '',
+  preferExpandedThinking = false,
   reasoningActive = false,
   reasoning = '',
   reasoningAlwaysVisible = false,
@@ -695,6 +696,7 @@ export const ToolTrail = memo(function ToolTrail({
   commandOverride?: boolean
   detailsMode?: DetailsMode
   outcome?: string
+  preferExpandedThinking?: boolean
   reasoningActive?: boolean
   reasoning?: string
   // MoA reference blocks (see Msg.isMoaReference) stay visible even when
@@ -721,6 +723,9 @@ export const ToolTrail = memo(function ToolTrail({
     [commandOverride, detailsMode, sections]
   )
 
+  const thinkingDefaultExpanded =
+    visible.thinking === 'expanded' && (preferExpandedThinking || commandOverride || sections?.thinking === 'expanded')
+
   const [now, setNow] = useState(() => Date.now())
   // Local toggles own the open state once mounted.  Init from the resolved
   // section visibility so default-expanded sections (thinking/tools) render
@@ -735,7 +740,7 @@ export const ToolTrail = memo(function ToolTrail({
   // label. This only affects the initial mount value; the re-sync effect
   // below deliberately does NOT re-apply it, so a manual collapse still
   // sticks (see the no-OR-at-effect-time warning above, #14968).
-  const [openThinking, setOpenThinking] = useState(visible.thinking === 'expanded' || reasoningAlwaysVisible)
+  const [openThinking, setOpenThinking] = useState(thinkingDefaultExpanded || reasoningAlwaysVisible)
   const [openTools, setOpenTools] = useState(visible.tools === 'expanded')
   const [openSubagents, setOpenSubagents] = useState(visible.subagents === 'expanded')
   const [deepSubagents, setDeepSubagents] = useState(visible.subagents === 'expanded')
@@ -766,11 +771,11 @@ export const ToolTrail = memo(function ToolTrail({
       return
     }
 
-    setOpenThinking(visible.thinking === 'expanded')
+    setOpenThinking(thinkingDefaultExpanded)
     setOpenTools(visible.tools === 'expanded')
     setOpenSubagents(visible.subagents === 'expanded')
     setOpenMeta(visible.activity === 'expanded')
-  }, [visible])
+  }, [thinkingDefaultExpanded, visible])
 
   const cot = useMemo(() => thinkingPreview(reasoning, 'full', THINKING_COT_MAX), [reasoning])
 

ui-tui/src/lib/virtualHeights.ts

@@ -74,6 +74,7 @@ export const estimatedMsgHeight = (
     details,
     leadGap = false,
     thinkingVisible = details,
+    thinkingExpanded = thinkingVisible,
     toolsVisible = details,
     userPrompt = '',
     withSeparator = false
@@ -81,6 +82,7 @@ export const estimatedMsgHeight = (
     compact: boolean
     details: boolean
     leadGap?: boolean
+    thinkingExpanded?: boolean
     thinkingVisible?: boolean
     toolsVisible?: boolean
     userPrompt?: string
@@ -124,7 +126,7 @@ export const estimatedMsgHeight = (
     if (hasVisibleDetails) {
       h +=
         (hasVisibleTools ? (msg.tools?.length ?? 0) : 0) +
-        (hasVisibleThinking ? wrappedLines(msg.thinking ?? '', bodyWidth) : 0)
+        (hasVisibleThinking ? (thinkingExpanded ? wrappedLines(msg.thinking ?? '', bodyWidth) : 1) : 0)
 
       if (msg.role === 'assistant' && /\S/.test(msg.text)) {
         h += 2