diff --git a/ui-tui/src/lib/liveProgress.test.ts b/ui-tui/src/lib/liveProgress.test.ts
index d10e1bb9a1f..141fb7acdc2 100644
--- a/ui-tui/src/lib/liveProgress.test.ts
+++ b/ui-tui/src/lib/liveProgress.test.ts
@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest'
 
-import { appendToolShelfMessage, isTodoDone } from './liveProgress.js'
+import { appendToolShelfMessage, canHoldToolShelf, isTodoDone, mergeToolShelfInto } from './liveProgress.js'
 
 describe('isTodoDone', () => {
   it('only treats non-empty all-completed/cancelled lists as done', () => {
@@ -16,6 +16,23 @@ describe('isTodoDone', () => {
   })
 })
 
+describe('tool shelf helpers', () => {
+  it('recognizes contextual thinking shelves as holders', () => {
+    expect(canHoldToolShelf({ kind: 'trail', role: 'system', text: '', thinking: 'plan' })).toBe(true)
+    expect(canHoldToolShelf({ kind: 'trail', role: 'system', text: '', tools: ['one ✓'] })).toBe(true)
+    expect(canHoldToolShelf({ role: 'assistant', text: 'done' })).toBe(false)
+  })
+
+  it('merges source rows into an existing shelf', () => {
+    expect(
+      mergeToolShelfInto(
+        { kind: 'trail', role: 'system', text: '', thinking: 'plan', tools: ['one ✓'] },
+        { kind: 'trail', role: 'system', text: '', tools: ['two ✓'] }
+      )
+    ).toEqual({ kind: 'trail', role: 'system', text: '', thinking: 'plan', tools: ['one ✓', 'two ✓'] })
+  })
+})
+
 describe('appendToolShelfMessage', () => {
   it('merges adjacent tool shelves into one contextual shelf', () => {
     const merged = appendToolShelfMessage([{ kind: 'trail', role: 'system', text: '', tools: ['one ✓'] }], {
diff --git a/ui-tui/src/lib/liveProgress.ts b/ui-tui/src/lib/liveProgress.ts
index 62f741633ce..9666e4312c1 100644
--- a/ui-tui/src/lib/liveProgress.ts
+++ b/ui-tui/src/lib/liveProgress.ts
@@ -6,9 +6,14 @@ export const isTodoDone = (todos: readonly TodoItem[]) =>
 export const isToolShelfMessage = (msg: Msg | undefined) =>
   Boolean(msg?.kind === 'trail' && !msg.text && !msg.thinking?.trim() && msg.tools?.length)
 
-const canHoldToolShelf = (msg: Msg | undefined) =>
+export const canHoldToolShelf = (msg: Msg | undefined) =>
   Boolean(msg?.kind === 'trail' && !msg.text && (msg.thinking?.trim() || msg.tools?.length))
 
+export const mergeToolShelfInto = (target: Msg, source: Msg): Msg => ({
+  ...target,
+  tools: [...(target.tools ?? []), ...(source.tools ?? [])]
+})
+
 export const appendToolShelfMessage = (prev: readonly Msg[], msg: Msg): Msg[] => {
   if (!isToolShelfMessage(msg)) {
     return [...prev, msg]
@@ -20,7 +25,7 @@ export const appendToolShelfMessage = (prev: readonly Msg[], msg: Msg): Msg[] =>
     if (canHoldToolShelf(candidate)) {
       const next = [...prev]
 
-      next[index] = { ...candidate!, tools: [...(candidate!.tools ?? []), ...(msg.tools ?? [])] }
+      next[index] = mergeToolShelfInto(candidate!, msg)
 
       return next
     }