diff --git a/ui-tui/src/app.tsx b/ui-tui/src/app.tsx
index 0cf63fd53c..e0ccff15bc 100644
--- a/ui-tui/src/app.tsx
+++ b/ui-tui/src/app.tsx
@@ -45,6 +45,7 @@ import type {
   SessionInfo,
   SlashCatalog,
   SudoReq,
+  ThinkingMode,
   Usage
 } from './types.js'
 
@@ -351,6 +352,7 @@ export function App({ gw }: { gw: GatewayClient }) {
   const [sessionStartedAt, setSessionStartedAt] = useState(() => Date.now())
   const [bellOnComplete, setBellOnComplete] = useState(false)
   const [clockNow, setClockNow] = useState(() => Date.now())
+  const [thinkingMode, setThinkingMode] = useState<ThinkingMode>('truncated')
 
   // ── Refs ─────────────────────────────────────────────────────────
 
@@ -390,6 +392,7 @@ export function App({ gw }: { gw: GatewayClient }) {
 
   const empty = !messages.length
   const isBlocked = blocked()
+  const hasAnyThinking = Boolean(reasoning.trim() || historyItems.some(m => m.thinking?.trim()))
 
   // ── Resize RPC ───────────────────────────────────────────────────
 
@@ -1181,6 +1184,16 @@ export function App({ gw }: { gw: GatewayClient }) {
       return
     }
 
+    if (ctrl(key, ch, 't')) {
+      if (hasAnyThinking) {
+        setThinkingMode(mode => (mode === 'collapsed' ? 'truncated' : mode === 'truncated' ? 'full' : 'collapsed'))
+      } else {
+        sys('no thinking available')
+      }
+
+      return
+    }
+
     if (ctrl(key, ch, 'b')) {
       if (voiceRecording) {
         setVoiceRecording(false)
@@ -2401,9 +2414,11 @@ export function App({ gw }: { gw: GatewayClient }) {
 
   const durationLabel = sid ? fmtDuration(clockNow - sessionStartedAt) : ''
   const voiceLabel = voiceRecording ? 'REC' : voiceProcessing ? 'STT' : `voice ${voiceEnabled ? 'on' : 'off'}`
-  const showProgressArea = Boolean(
-    (busy && !streaming) || (busy ? activity.length : 0) || tools.length || turnTrail.length
-  )
+
+  const hasReasoning = Boolean(reasoning.trim())
+
+  const showProgressArea = Boolean(busy || tools.length || turnTrail.length || hasReasoning)
+
   const showStreamingArea = Boolean(streaming)
 
   // ── Render ───────────────────────────────────────────────────────
@@ -2420,7 +2435,7 @@ export function App({ gw }: { gw: GatewayClient }) {
           ) : m.kind === 'panel' && m.panelData ? (
             <Panel sections={m.panelData.sections} t={theme} title={m.panelData.title} />
           ) : (
-            <MessageLine cols={cols} compact={compact} msg={m} t={theme} />
+            <MessageLine cols={cols} compact={compact} msg={m} t={theme} thinkingMode={thinkingMode} />
           )}
         </Box>
       ))}
@@ -2431,8 +2446,9 @@ export function App({ gw }: { gw: GatewayClient }) {
             <ToolTrail
               activity={busy ? activity : []}
               busy={busy && !streaming}
-              reasoning={busy && !streaming ? reasoning : ''}
+              reasoning={reasoning}
               t={theme}
+              thinkingMode={hasReasoning ? thinkingMode : 'truncated'}
               tools={tools}
               trail={turnTrail}
             />
diff --git a/ui-tui/src/components/messageLine.tsx b/ui-tui/src/components/messageLine.tsx
index 07a8fbd5af..2ab0e22728 100644
--- a/ui-tui/src/components/messageLine.tsx
+++ b/ui-tui/src/components/messageLine.tsx
@@ -2,9 +2,9 @@ import { Ansi, Box, Text } from '@hermes/ink'
 import { memo } from 'react'
 
 import { LONG_MSG, ROLE } from '../constants.js'
-import { compactPreview, hasAnsi, isPasteBackedText, stripAnsi, userDisplay } from '../lib/text.js'
+import { compactPreview, hasAnsi, isPasteBackedText, stripAnsi, thinkingPreview, userDisplay } from '../lib/text.js'
 import type { Theme } from '../theme.js'
-import type { Msg } from '../types.js'
+import type { Msg, ThinkingMode } from '../types.js'
 
 import { Md } from './markdown.js'
 import { ToolTrail } from './thinking.js'
@@ -12,18 +12,20 @@ import { ToolTrail } from './thinking.js'
 export const MessageLine = memo(function MessageLine({
   cols,
   compact,
+  thinkingMode = 'truncated',
   msg,
   t
 }: {
   cols: number
   compact?: boolean
+  thinkingMode?: ThinkingMode
   msg: Msg
   t: Theme
 }) {
   if (msg.kind === 'trail' && msg.tools?.length) {
     return (
       <Box flexDirection="column" marginTop={1}>
-        <ToolTrail t={t} trail={msg.tools} />
+        <ToolTrail t={t} thinkingMode={thinkingMode} trail={msg.tools} />
       </Box>
     )
   }
@@ -41,6 +43,9 @@ export const MessageLine = memo(function MessageLine({
   }
 
   const { body, glyph, prefix } = ROLE[msg.role](t)
+  const thinking = msg.thinking?.replace(/\n/g, ' ').trim() ?? ''
+  const preview = thinkingPreview(thinking, thinkingMode, Math.min(96, Math.max(32, cols - 18)))
+  const showThinkingPreview = Boolean(preview && !msg.tools?.length)
 
   const content = (() => {
     if (msg.kind === 'slash') {
@@ -80,18 +85,19 @@ export const MessageLine = memo(function MessageLine({
       marginBottom={msg.role === 'user' ? 1 : 0}
       marginTop={msg.role === 'user' || msg.kind === 'slash' ? 1 : 0}
     >
-      {msg.thinking && (
-        <Text color={t.color.dim} dimColor wrap="truncate-end">
-          💭 {msg.thinking.replace(/\n/g, ' ').slice(0, 200)}
-        </Text>
-      )}
-
       {msg.tools?.length ? (
         <Box flexDirection="column" marginBottom={1}>
-          <ToolTrail t={t} trail={msg.tools} />
+          <ToolTrail reasoning={thinking} t={t} thinkingMode={thinkingMode} trail={msg.tools} />
         </Box>
       ) : null}
 
+      {showThinkingPreview && (
+        <Text color={t.color.dim} dimColor {...(thinkingMode !== 'full' ? { wrap: 'truncate-end' as const } : {})}>
+          {'└ '}
+          {preview}
+        </Text>
+      )}
+
       <Box>
         <Box flexShrink={0} width={3}>
           <Text bold={msg.role === 'user'} color={prefix}>
diff --git a/ui-tui/src/components/textInput.tsx b/ui-tui/src/components/textInput.tsx
index 6378a55c48..385dd5f48b 100644
--- a/ui-tui/src/components/textInput.tsx
+++ b/ui-tui/src/components/textInput.tsx
@@ -329,6 +329,7 @@ export function TextInput({
         k.upArrow ||
         k.downArrow ||
         (k.ctrl && inp === 'c') ||
+        (k.ctrl && inp === 't') ||
         k.tab ||
         (k.shift && k.tab) ||
         k.pageUp ||
diff --git a/ui-tui/src/components/thinking.tsx b/ui-tui/src/components/thinking.tsx
index a5f876da1f..4e609f5e6e 100644
--- a/ui-tui/src/components/thinking.tsx
+++ b/ui-tui/src/components/thinking.tsx
@@ -7,14 +7,12 @@ import {
   formatToolCall,
   parseToolTrailResultLine,
   pick,
-  scaleHex,
-  THINKING_COT_FADE,
   THINKING_COT_MAX,
-  thinkingCotTail,
+  thinkingPreview,
   toolTrailLabel
 } from '../lib/text.js'
 import type { Theme } from '../theme.js'
-import type { ActiveTool, ActivityItem } from '../types.js'
+import type { ActiveTool, ActivityItem, ThinkingMode } from '../types.js'
 
 const THINK: BrailleSpinnerName[] = ['helix', 'breathe', 'orbit', 'dna', 'waverows', 'snake', 'pulse']
 const TOOL: BrailleSpinnerName[] = ['cascade', 'scan', 'diagswipe', 'fillsweep', 'rain', 'columns', 'sparkle']
@@ -49,10 +47,10 @@ export function Spinner({ color, variant = 'think' }: { color: string; variant?:
 
 type DetailRow = { color: string; content: ReactNode; dimColor?: boolean; key: string }
 
-function Detail({ color, content, dimColor, t }: DetailRow & { t: Theme }) {
+function Detail({ color, content, dimColor }: DetailRow) {
   return (
     <Text color={color} dimColor={dimColor}>
-      <Text dimColor> └ </Text>
+      <Text dimColor>└ </Text>
       {content}
     </Text>
   )
@@ -60,7 +58,15 @@ function Detail({ color, content, dimColor, t }: DetailRow & { t: Theme }) {
 
 // ── Thinking (pre-tool fallback) ─────────────────────────────────────
 
-export const Thinking = memo(function Thinking({ reasoning, t }: { reasoning: string; t: Theme }) {
+export const Thinking = memo(function Thinking({
+  mode = 'truncated',
+  reasoning,
+  t
+}: {
+  mode?: ThinkingMode
+  reasoning: string
+  t: Theme
+}) {
   const [tick, setTick] = useState(0)
 
   useEffect(() => {
@@ -69,8 +75,7 @@ export const Thinking = memo(function Thinking({ reasoning, t }: { reasoning: st
     return () => clearInterval(id)
   }, [])
 
-  const tail = thinkingCotTail(reasoning)
-  const clipped = reasoning.length > THINKING_COT_MAX
+  const preview = thinkingPreview(reasoning, mode, THINKING_COT_MAX)
 
   return (
     <Box flexDirection="column">
@@ -79,18 +84,10 @@ export const Thinking = memo(function Thinking({ reasoning, t }: { reasoning: st
         {VERBS[tick % VERBS.length] ?? 'thinking'}…
       </Text>
 
-      {tail ? (
-        <Text wrap="truncate-end">
-          {clipped &&
-            Array.from({ length: Math.min(THINKING_COT_FADE, tail.length) }, (_, i) => (
-              <Text color={scaleHex(t.color.dim, (i + 1) / (THINKING_COT_FADE + 1))} key={i}>
-                {tail[i]}
-              </Text>
-            ))}
-
-          <Text color={t.color.dim} dimColor>
-            {clipped ? tail.slice(THINKING_COT_FADE) : tail}
-          </Text>
+      {preview ? (
+        <Text color={t.color.dim} dimColor {...(mode !== 'full' ? { wrap: 'truncate-end' as const } : {})}>
+          <Text dimColor>└ </Text>
+          {preview}
         </Text>
       ) : null}
     </Box>
@@ -103,6 +100,7 @@ type Group = { color: string; content: ReactNode; details: DetailRow[]; key: str
 
 export const ToolTrail = memo(function ToolTrail({
   busy = false,
+  thinkingMode = 'truncated',
   reasoning = '',
   t,
   tools = [],
@@ -110,6 +108,7 @@ export const ToolTrail = memo(function ToolTrail({
   activity = []
 }: {
   busy?: boolean
+  thinkingMode?: ThinkingMode
   reasoning?: string
   t: Theme
   tools?: ActiveTool[]
@@ -122,12 +121,15 @@ export const ToolTrail = memo(function ToolTrail({
     if (!tools.length) {
       return
     }
+
     const id = setInterval(() => setNow(Date.now()), 200)
 
     return () => clearInterval(id)
   }, [tools.length])
 
-  if (!busy && !trail.length && !tools.length && !activity.length) {
+  const reasoningTail = thinkingPreview(reasoning, thinkingMode, THINKING_COT_MAX)
+
+  if (!busy && !trail.length && !tools.length && !activity.length && !reasoningTail) {
     return null
   }
 
@@ -211,11 +213,7 @@ export const ToolTrail = memo(function ToolTrail({
     })
   }
 
-  // ── reasoning tail → child of last group ────────────────────────
-
-  const reasoningTail = thinkingCotTail(reasoning)
-
-  if (groups.length && reasoningTail) {
+  if (reasoningTail && groups.length) {
     detail({ color: t.color.dim, content: reasoningTail, dimColor: true, key: 'cot' })
   }
 
@@ -232,7 +230,10 @@ export const ToolTrail = memo(function ToolTrail({
 
   return (
     <Box flexDirection="column">
-      {busy && !groups.length && <Thinking reasoning={reasoning} t={t} />}
+      {busy && !groups.length && <Thinking mode={thinkingMode} reasoning={reasoning} t={t} />}
+      {!busy && !groups.length && reasoningTail && (
+        <Detail color={t.color.dim} content={reasoningTail} dimColor key="cot" />
+      )}
 
       {groups.map(g => (
         <Box flexDirection="column" key={g.key}>
@@ -242,7 +243,7 @@ export const ToolTrail = memo(function ToolTrail({
           </Text>
 
           {g.details.map(d => (
-            <Detail {...d} key={d.key} t={t} />
+            <Detail {...d} key={d.key} />
           ))}
         </Box>
       ))}
diff --git a/ui-tui/src/constants.ts b/ui-tui/src/constants.ts
index 59fc639282..9f1c487711 100644
--- a/ui-tui/src/constants.ts
+++ b/ui-tui/src/constants.ts
@@ -24,6 +24,7 @@ export const HOTKEYS: [string, string][] = [
   ['Ctrl+D', 'exit'],
   ['Ctrl+G', 'open $EDITOR for prompt'],
   ['Ctrl+L', 'new session (clear)'],
+  ['Ctrl+T', 'cycle thinking detail'],
   ['Ctrl+V / Alt+V', 'paste clipboard image'],
   ['Tab', 'apply completion'],
   ['↑/↓', 'completions / queue edit / history'],
diff --git a/ui-tui/src/lib/text.ts b/ui-tui/src/lib/text.ts
index 30dcd67e31..9bed6c3c15 100644
--- a/ui-tui/src/lib/text.ts
+++ b/ui-tui/src/lib/text.ts
@@ -1,4 +1,5 @@
 import { INTERPOLATION_RE, LONG_MSG } from '../constants.js'
+import type { ThinkingMode } from '../types.js'
 
 // eslint-disable-next-line no-control-regex
 const ANSI_RE = /\x1b\[[0-9;]*m/g
@@ -42,6 +43,12 @@ export const compactPreview = (s: string, max: number) => {
   return !one ? '' : one.length > max ? one.slice(0, max - 1) + '…' : one
 }
 
+export const thinkingPreview = (reasoning: string, mode: ThinkingMode, max: number) => {
+  const text = reasoning.replace(/\n/g, ' ').trim()
+
+  return !text || mode === 'collapsed' ? '' : mode === 'full' ? text : compactPreview(text, max)
+}
+
 export const toolTrailLabel = (name: string) =>
   name
     .split('_')
@@ -109,21 +116,6 @@ export const lastCotTrailIndex = (trail: readonly string[]) => {
 }
 
 export const THINKING_COT_MAX = 160
-export const THINKING_COT_FADE = 5
-
-export const thinkingCotTail = (reasoning: string) => reasoning.replace(/\n/g, ' ').slice(-THINKING_COT_MAX)
-
-/** Scale #RRGGBB by k ∈ [0,1] — used for left-edge fade toward terminal bg. */
-export const scaleHex = (hex: string, k: number) => {
-  const h = hex.replace('#', '')
-
-  const ch = (o: number) =>
-    Math.round(parseInt(h.slice(o, o + 2), 16) * k)
-      .toString(16)
-      .padStart(2, '0')
-
-  return `#${ch(0)}${ch(2)}${ch(4)}`
-}
 
 export const estimateRows = (text: string, w: number, compact = false) => {
   let fence: { char: '`' | '~'; len: number } | null = null
diff --git a/ui-tui/src/types.ts b/ui-tui/src/types.ts
index ddffc566c5..8f24ba7ac5 100644
--- a/ui-tui/src/types.ts
+++ b/ui-tui/src/types.ts
@@ -33,6 +33,7 @@ export interface Msg {
 }
 
 export type Role = 'assistant' | 'system' | 'tool' | 'user'
+export type ThinkingMode = 'collapsed' | 'truncated' | 'full'
 
 export interface SessionInfo {
   cwd?: string