opentui(ts): deferClose helper for overlay-close defers

Extract the repeated `setTimeout(() => …close…, 0)` overlay/prompt-close
pattern into a single `deferClose(fn)` helper (src/logic/defer.ts) so the
"why deferred" rationale (let the closing keystroke finish dispatching before
the composer remounts/refocuses) lives in one place.

Rewires the 5 close-defer sites: closePager/closeDashboard/closeSwitcher/
closePicker in view/App.tsx and clearSoon in view/prompts/promptOverlay.tsx.
Timing is unchanged (0ms). Other setTimeout uses (quit window, flashHint,
scroll re-anchor, resize debounce, transport) are NOT close-defers and are
left untouched.

ui-tui-opentui-v2/src/logic/defer.ts

@@ -0,0 +1,12 @@
+/**
+ * deferClose — defer an overlay/prompt close by one tick.
+ *
+ * Overlays REPLACE the composer (a `<Switch>`), so when one closes the composer
+ * remounts + refocuses. Running the close on the NEXT tick lets the current
+ * key/close event (Esc/q/Enter/y/select) finish dispatching first, so the
+ * keystroke that triggered the close can't leak into the freshly-focused
+ * composer (e.g. `/clear`→y once left a stray "y" in the input).
+ */
+export function deferClose(fn: () => void): void {
+  setTimeout(fn, 0)
+}

ui-tui-opentui-v2/src/view/App.tsx

@@ -15,6 +15,7 @@
  */
 import { Match, Switch } from 'solid-js'
 
+import { deferClose } from '../logic/defer.ts'
 import type { PromptHistory } from '../logic/history.ts'
 import type { PasteStore } from '../logic/pastes.ts'
 import type { SessionStore } from '../logic/store.ts'
@@ -56,11 +57,11 @@ export function App(props: AppProps) {
   const switcher = () => props.store.state.switcher
   const picker = () => props.store.state.picker
   // Defer the close so the key that closed an overlay (Esc/q/Enter) can't land in
-  // the freshly-remounted composer.
-  const closePager = () => setTimeout(() => props.store.closePager(), 0)
-  const closeDashboard = () => setTimeout(() => props.store.closeDashboard(), 0)
-  const closeSwitcher = () => setTimeout(() => props.store.closeSwitcher(), 0)
-  const closePicker = () => setTimeout(() => props.store.closePicker(), 0)
+  // the freshly-remounted composer (see deferClose).
+  const closePager = () => deferClose(() => props.store.closePager())
+  const closeDashboard = () => deferClose(() => props.store.closeDashboard())
+  const closeSwitcher = () => deferClose(() => props.store.closeSwitcher())
+  const closePicker = () => deferClose(() => props.store.closePicker())
   const resume = (id: string) => {
     ;(props.onResume ?? NOOP_RESUME)(id)
     closeSwitcher()

ui-tui-opentui-v2/src/view/prompts/promptOverlay.tsx

@@ -11,6 +11,7 @@
  */
 import { Match, Switch } from 'solid-js'
 
+import { deferClose } from '../../logic/defer.ts'
 import type { SessionStore } from '../../logic/store.ts'
 import { ApprovalPrompt } from './approvalPrompt.tsx'
 import { ClarifyPrompt } from './clarifyPrompt.tsx'
@@ -28,7 +29,7 @@ export function PromptOverlay(props: PromptOverlayProps) {
   // Defer the prompt-clear (which remounts + refocuses the composer) past the
   // CURRENT keystroke, so the key that answered the prompt (Enter/y/select) can't
   // leak into the freshly-focused composer (e.g. `/clear`→y left "y" in the input).
-  const clearSoon = () => setTimeout(() => props.store.clearPrompt(), 0)
+  const clearSoon = () => deferClose(() => props.store.clearPrompt())
   const respond = (method: string, params: Record<string, unknown>) => {
     props.onRespond(method, params)
     clearSoon()