[BUG] AskUserQuestion tool call consistently interrupted ("Tool execution was interrupted")

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Description

The AskUserQuestion tool fails to render/complete every time it's invoked. The call is interrupted before the interactive question widget ever appears, and no result is returned to the model — it gets [Tool result missing due to internal error].

Steps to reproduce

1. Start a Claude Code session (tested in both the VS Code extension and the desktop app).
2. Trigger any flow that calls the AskUserQuestion tool (e.g. a skill that asks a clarifying question, or a direct tool call).
3. Observe: the question payload is shown briefly, then the UI shows "Tool execution was interrupted." No options are selectable, and the model never receives an answer.

Environment

• OS: Windows 11
• Tested in: VS Code extension (Claude Code) — reproduced
• Tested in: Claude Code desktop app — reproduced (rules out VS Code-specific cause)
• Claude Code extension: up to date at time of testing
• Restarting VS Code and a full PC reboot did not resolve the issue

Expected behavior

The question widget should render with its options, allow the user to select an answer, and return that answer to the model so the conversation can continue.

Actual behavior

The tool call is interrupted every time, in both clients, with no error detail beyond "Tool execution was interrupted" / "[Tool result missing due to internal error]". This blocks any workflow that depends on interactive clarifying questions (e.g. skills that ask setup questions before starting work).

Additional notes

This appears to be session- or account-level rather than client-specific, since it reproduces identically across two different Claude Code clients on the same machine.

What Should Happen?

The AskUserQuestion widget should render with its selectable options, let me pick an answer (or select "Other" to type a custom one), and send that answer back to the model so the conversation continues normally. Right now the call is interrupted before the widget appears, so no answer is ever captured and the flow stalls.

Error Messages/Logs

Steps to Reproduce

1. Open a Claude Code session (reproduced in both the VS Code extension and the desktop app).
2. Trigger any flow that invokes the AskUserQuestion tool — e.g. run a skill that asks a clarifying question at the start (in my case, the gstack /spec skill), or have the model call AskUserQuestion directly.
3. Watch the response: the question and its options are briefly shown, then the UI reports "Tool execution was interrupted" and the model receives "[Tool result missing due to internal error]" instead of an answer.
4. Repeat — the failure is consistent, not intermittent. It happened on every attempt (4+ times), across two different Claude Code clients, and survived a full VS Code restart and a full PC reboot.

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.201

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_