diff --git a/ui-tui/src/__tests__/interactionMode.test.ts b/ui-tui/src/__tests__/interactionMode.test.ts
deleted file mode 100644
index 1a44519ddb..0000000000
--- a/ui-tui/src/__tests__/interactionMode.test.ts
+++ /dev/null
@@ -1,28 +0,0 @@
-import { afterEach, describe, expect, it, vi } from 'vitest'
-
-import { getInteractionMode, markScrolling, markTyping, resetInteractionMode } from '../app/interactionMode.js'
-import { SCROLLING_IDLE_MS, TYPING_IDLE_MS } from '../config/timing.js'
-
-describe('interactionMode', () => {
-  afterEach(() => {
-    resetInteractionMode()
-    vi.useRealTimers()
-  })
-
-  it('holds scrolling mode briefly then returns idle', () => {
-    vi.useFakeTimers()
-    markScrolling()
-    expect(getInteractionMode()).toBe('scrolling')
-    vi.advanceTimersByTime(SCROLLING_IDLE_MS)
-    expect(getInteractionMode()).toBe('idle')
-  })
-
-  it('typing takes priority over scrolling', () => {
-    vi.useFakeTimers()
-    markTyping()
-    markScrolling()
-    expect(getInteractionMode()).toBe('typing')
-    vi.advanceTimersByTime(TYPING_IDLE_MS)
-    expect(getInteractionMode()).toBe('idle')
-  })
-})
diff --git a/ui-tui/src/app/interactionMode.ts b/ui-tui/src/app/interactionMode.ts
deleted file mode 100644
index f18033f81c..0000000000
--- a/ui-tui/src/app/interactionMode.ts
+++ /dev/null
@@ -1,52 +0,0 @@
-import { SCROLLING_IDLE_MS, TYPING_IDLE_MS } from '../config/timing.js'
-
-export type InteractionMode = 'idle' | 'scrolling' | 'typing'
-
-type Timer = null | ReturnType<typeof setTimeout>
-
-let mode: InteractionMode = 'idle'
-let scrollingTimer: Timer = null
-let typingTimer: Timer = null
-
-const clear = (t: Timer): null => {
-  if (t) {
-    clearTimeout(t)
-  }
-
-  return null
-}
-
-export function getInteractionMode(): InteractionMode {
-  return mode
-}
-
-export function markTyping(): void {
-  mode = 'typing'
-  typingTimer = clear(typingTimer)
-  scrollingTimer = clear(scrollingTimer)
-  typingTimer = setTimeout(() => {
-    typingTimer = null
-    mode = 'idle'
-  }, TYPING_IDLE_MS)
-}
-
-export function markScrolling(): void {
-  if (mode === 'typing') {
-    return
-  }
-
-  mode = 'scrolling'
-  scrollingTimer = clear(scrollingTimer)
-  scrollingTimer = setTimeout(() => {
-    scrollingTimer = null
-    if (mode === 'scrolling') {
-      mode = 'idle'
-    }
-  }, SCROLLING_IDLE_MS)
-}
-
-export function resetInteractionMode(): void {
-  scrollingTimer = clear(scrollingTimer)
-  typingTimer = clear(typingTimer)
-  mode = 'idle'
-}
diff --git a/ui-tui/src/app/useSubmission.ts b/ui-tui/src/app/useSubmission.ts
index 70a3faf329..6a585bd61d 100644
--- a/ui-tui/src/app/useSubmission.ts
+++ b/ui-tui/src/app/useSubmission.ts
@@ -101,10 +101,10 @@ export function useSubmission(opts: UseSubmissionOptions) {
 
         gw.request<PromptSubmitResponse>('prompt.submit', { session_id: sid, text: submitText }).catch((e: Error) => {
           if (isSessionBusyError(e)) {
-            composerActions.enqueue(text)
+            composerActions.enqueue(submitText)
             patchUiState({ busy: true, status: 'queued for next turn' })
 
-            return sys(`queued: "${text.slice(0, 50)}${text.length > 50 ? '…' : ''}"`)
+            return sys(`queued: "${submitText.slice(0, 50)}${submitText.length > 50 ? '…' : ''}"`)
           }
 
           sys(`error: ${e.message}`)
diff --git a/ui-tui/src/config/timing.ts b/ui-tui/src/config/timing.ts
index d428bacfee..e0bd611b82 100644
--- a/ui-tui/src/config/timing.ts
+++ b/ui-tui/src/config/timing.ts
@@ -2,5 +2,4 @@ export const STREAM_BATCH_MS = 16
 export const STREAM_IDLE_BATCH_MS = 16
 export const STREAM_TYPING_BATCH_MS = 80
 export const TYPING_IDLE_MS = 250
-export const SCROLLING_IDLE_MS = 450
 export const REASONING_PULSE_MS = 700
diff --git a/ui-tui/src/lib/viewportStore.ts b/ui-tui/src/lib/viewportStore.ts
index 298d094bfb..0a52e99a87 100644
--- a/ui-tui/src/lib/viewportStore.ts
+++ b/ui-tui/src/lib/viewportStore.ts
@@ -1,6 +1,6 @@
 import type { ScrollBoxHandle } from '@hermes/ink'
 import type { RefObject } from 'react'
-import { useCallback, useSyncExternalStore } from 'react'
+import { useCallback, useMemo, useSyncExternalStore } from 'react'
 
 export interface ViewportSnapshot {
   atBottom: boolean
@@ -45,6 +45,19 @@ export function viewportSnapshotKey(v: ViewportSnapshot) {
   return `${v.atBottom ? 1 : 0}:${v.top}:${v.viewportHeight}:${v.scrollHeight}:${v.pending}`
 }
 
+const snapshotFromKey = (key: string): ViewportSnapshot => {
+  const [atBottom = '1', top = '0', viewportHeight = '0', scrollHeight = '0', pending = '0'] = key.split(':')
+
+  return {
+    atBottom: atBottom === '1',
+    bottom: Number(top) + Number(viewportHeight),
+    pending: Number(pending),
+    scrollHeight: Number(scrollHeight),
+    top: Number(top),
+    viewportHeight: Number(viewportHeight)
+  }
+}
+
 export function useViewportSnapshot(scrollRef: RefObject<ScrollBoxHandle | null>): ViewportSnapshot {
   const key = useSyncExternalStore(
     useCallback((cb: () => void) => scrollRef.current?.subscribe(cb) ?? (() => {}), [scrollRef]),
@@ -52,7 +65,5 @@ export function useViewportSnapshot(scrollRef: RefObject<ScrollBoxHandle | null>
     () => viewportSnapshotKey(EMPTY)
   )
 
-  void key
-
-  return getViewportSnapshot(scrollRef.current)
+  return useMemo(() => snapshotFromKey(key), [key])
 }