diff --git a/src/renderer/src/components/terminal-pane/terminal-ime-composer-placeholder-mask.test.ts b/src/renderer/src/components/terminal-pane/terminal-ime-composer-placeholder-mask.test.ts
index 34c41bc5fb6..21379833bc9 100644
--- a/src/renderer/src/components/terminal-pane/terminal-ime-composer-placeholder-mask.test.ts
+++ b/src/renderer/src/components/terminal-pane/terminal-ime-composer-placeholder-mask.test.ts
@@ -3,7 +3,6 @@ import { Terminal } from '@xterm/xterm'
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import {
   installTerminalImeComposerPlaceholderMask,
-  MAX_ACTIVE_COMPOSITION_SESSIONS,
   TERMINAL_IME_COMPOSER_PLACEHOLDER_CLASS
 } from './terminal-ime-composer-placeholder-mask'
 import {
@@ -200,7 +199,7 @@ describe('terminal IME composer placeholder mask', () => {
     expect(rig.element.classList.contains(TERMINAL_IME_COMPOSER_PLACEHOLDER_CLASS)).toBe(false)
   })
 
-  it('resets stale ownership at the session bound while keeping the newest session active', async () => {
+  it('keeps the newest session owner when an older session ends first', async () => {
     const rig = openTerminal()
     await rig.write(codexPlaceholderFrame())
 
@@ -213,17 +212,60 @@ describe('terminal IME composer placeholder mask', () => {
       )
     }
 
-    for (let id = 1; id <= MAX_ACTIVE_COMPOSITION_SESSIONS + 1; id += 1) {
-      dispatchSession(XTERM_COMPOSITION_SESSION_START_EVENT, id)
-    }
+    dispatchSession(XTERM_COMPOSITION_SESSION_START_EVENT, 1)
+    dispatchSession(XTERM_COMPOSITION_SESSION_START_EVENT, 2)
+    dispatchSession(XTERM_COMPOSITION_SESSION_END_EVENT, 1)
     expect(rig.element.classList.contains(TERMINAL_IME_COMPOSER_PLACEHOLDER_CLASS)).toBe(true)
 
-    for (let id = 1; id <= MAX_ACTIVE_COMPOSITION_SESSIONS; id += 1) {
+    dispatchSession(XTERM_COMPOSITION_SESSION_END_EVENT, 2)
+    expect(rig.element.classList.contains(TERMINAL_IME_COMPOSER_PLACEHOLDER_CLASS)).toBe(false)
+  })
+
+  it('clears the visible owner on a current end and ignores a late older end', async () => {
+    const rig = openTerminal()
+    await rig.write(codexPlaceholderFrame())
+
+    const dispatchSession = (type: string, id: number): void => {
+      rig.element.dispatchEvent(
+        new CustomEvent(type, {
+          bubbles: true,
+          detail: { id }
+        })
+      )
+    }
+
+    dispatchSession(XTERM_COMPOSITION_SESSION_START_EVENT, 11)
+    dispatchSession(XTERM_COMPOSITION_SESSION_START_EVENT, 12)
+    dispatchSession(XTERM_COMPOSITION_SESSION_END_EVENT, 12)
+    expect(rig.element.classList.contains(TERMINAL_IME_COMPOSER_PLACEHOLDER_CLASS)).toBe(false)
+
+    dispatchSession(XTERM_COMPOSITION_SESSION_END_EVENT, 11)
+    expect(rig.element.classList.contains(TERMINAL_IME_COMPOSER_PLACEHOLDER_CLASS)).toBe(false)
+  })
+
+  it('keeps ownership bounded across repeated starts and recovers on the newest end', async () => {
+    const rig = openTerminal()
+    await rig.write(codexPlaceholderFrame())
+
+    const dispatchSession = (type: string, id: number): void => {
+      rig.element.dispatchEvent(
+        new CustomEvent(type, {
+          bubbles: true,
+          detail: { id }
+        })
+      )
+    }
+
+    const newestId = 2048
+    for (let id = 1; id <= newestId; id += 1) {
+      dispatchSession(XTERM_COMPOSITION_SESSION_START_EVENT, id)
+    }
+    for (let id = 1; id < newestId; id += 1) {
       dispatchSession(XTERM_COMPOSITION_SESSION_END_EVENT, id)
     }
     expect(rig.element.classList.contains(TERMINAL_IME_COMPOSER_PLACEHOLDER_CLASS)).toBe(true)
 
-    dispatchSession(XTERM_COMPOSITION_SESSION_END_EVENT, MAX_ACTIVE_COMPOSITION_SESSIONS + 1)
+    dispatchSession(XTERM_COMPOSITION_SESSION_END_EVENT, newestId)
     expect(rig.element.classList.contains(TERMINAL_IME_COMPOSER_PLACEHOLDER_CLASS)).toBe(false)
   })
 })
diff --git a/src/renderer/src/components/terminal-pane/terminal-ime-composer-placeholder-mask.ts b/src/renderer/src/components/terminal-pane/terminal-ime-composer-placeholder-mask.ts
index 3d48d4502b3..bc009421598 100644
--- a/src/renderer/src/components/terminal-pane/terminal-ime-composer-placeholder-mask.ts
+++ b/src/renderer/src/components/terminal-pane/terminal-ime-composer-placeholder-mask.ts
@@ -7,9 +7,6 @@ import {
 } from './terminal-ime-composition-route'
 
 export const TERMINAL_IME_COMPOSER_PLACEHOLDER_CLASS = 'orca-ime-composer-placeholder'
-// One live composition and a few delayed turnovers are enough for xterm's lifecycle; a missing
-// session-end event must not retain ownership forever.
-export const MAX_ACTIVE_COMPOSITION_SESSIONS = 8
 
 function compositionSessionId(event: Event): number | null {
   if (!(event instanceof CustomEvent)) {
@@ -25,10 +22,12 @@ export function installTerminalImeComposerPlaceholderMask(terminal: Terminal): I
     return { dispose: () => undefined }
   }
 
-  const activeSessions = new Set<number>()
+  // xterm renders one composition view; a newer transaction supersedes any older pending one.
+  // Keeping only its id makes malformed/repeated starts bounded without evicting live ownership.
+  let activeSessionId: number | null = null
   const syncPlaceholderOwnership = (): void => {
     const ownsPlaceholder =
-      activeSessions.size > 0 &&
+      activeSessionId !== null &&
       hasTerminalComposerPlaceholder(readTerminalCursorLineContext(terminal, terminal.rows))
     element.classList.toggle(TERMINAL_IME_COMPOSER_PLACEHOLDER_CLASS, ownsPlaceholder)
   }
@@ -37,11 +36,7 @@ export function installTerminalImeComposerPlaceholderMask(terminal: Terminal): I
     if (id === null) {
       return
     }
-    if (!activeSessions.has(id) && activeSessions.size >= MAX_ACTIVE_COMPOSITION_SESSIONS) {
-      // Drop stale ownership before adopting the newest transaction.
-      activeSessions.clear()
-    }
-    activeSessions.add(id)
+    activeSessionId = id
     syncPlaceholderOwnership()
   }
   const handleSessionEnd = (event: Event): void => {
@@ -49,11 +44,13 @@ export function installTerminalImeComposerPlaceholderMask(terminal: Terminal): I
     if (id === null) {
       return
     }
-    activeSessions.delete(id)
+    if (activeSessionId === id) {
+      activeSessionId = null
+    }
     syncPlaceholderOwnership()
   }
   const handleBlur = (): void => {
-    activeSessions.clear()
+    activeSessionId = null
     syncPlaceholderOwnership()
   }
 
@@ -61,14 +58,14 @@ export function installTerminalImeComposerPlaceholderMask(terminal: Terminal): I
   element.addEventListener(XTERM_COMPOSITION_SESSION_END_EVENT, handleSessionEnd)
   element.addEventListener('blur', handleBlur, true)
   const renderDisposable = terminal.onRender(() => {
-    if (activeSessions.size > 0) {
+    if (activeSessionId !== null) {
       syncPlaceholderOwnership()
     }
   })
 
   return {
     dispose: () => {
-      activeSessions.clear()
+      activeSessionId = null
       element.classList.remove(TERMINAL_IME_COMPOSER_PLACEHOLDER_CLASS)
       element.removeEventListener(XTERM_COMPOSITION_SESSION_START_EVENT, handleSessionStart)
       element.removeEventListener(XTERM_COMPOSITION_SESSION_END_EVENT, handleSessionEnd)