Windows computer-use breaks IME candidate window (Chinese/CJK input) after keystroke injection

After Claude uses the computer-use tool to type text or press keys on Windows, the IME (Microsoft Pinyin) candidate / composition window stops appearing. Typing pinyin produces no candidate popup, which makes Chinese input impossible until the input stack is manually reset.

Environment

• OS: Windows 11 Pro (build 26200)
• IME: Microsoft Pinyin (CHS)

Repro

1. Run any computer-use session that types text / presses keys.
2. After it finishes, focus any text field and try to type Chinese (pinyin).
3. No candidate window appears — characters cannot be composed.

Diagnosis

• ctfmon.exe and TextInputHost.exe are still running and responsive after the break.
• The Microsoft Pinyin registry settings (cloud candidate, dynamic ranking, self-learning, etc.) are intact.
• Killing / restarting TextInputHost.exe immediately restores the candidate window.

This indicates the synthetic input injection leaves the candidate-window renderer (TextInputHost / Text Services Framework) in a broken state, rather than crashing it or changing user settings.

Impact

• Recurs after every computer-use session that performs typing.
• Affects all users relying on a CJK IME; English-only users will not notice it.

Suggested fix

Restore / re-associate the IME input context after performing synthetic keyboard input on Windows.