[BUG] Enter now interrupts instead of queueing while Claude is working (regression)

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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?

In the Claude desktop app (Code tab, Windows), pressing Enter while Claude is working now interrupts the running turn every time. It used to queue the message and deliver it after the turn finished. The running tool call is cut off and the transcript shows `[Request interrupted by user]`. Ctrl+X Enter (the CLI `chat:queueSubmit` chord) does nothing in the desktop app, and there is no setting, modifier key, or UI control that queues instead of interrupting, so there is no workaround inside the app.

Environment: Claude desktop app 1.49585.0.0 (Microsoft Store install), Windows 11 Home 10.0.26200 (64-bit). No changelog entry for Claude Code 2.1.257–2.1.265 mentions Enter/queue/interrupt. Related earlier desktop-queue issues: #57497, #66310, #71726.

### What Should Happen?

A message sent while Claude is working should be queued and delivered when the current turn ends, as it did before, or the app should offer an explicit queue key like the CLI's Ctrl+X Enter or Ctrl + Enter (I think it was Ctrl + Enter for my desktop app before). Surprisingly, the CLI version works (Windows terminal)

### Error Messages/Logs

```shell
No error. The transcript shows:

[Request interrupted by user]

```

### Steps to Reproduce

1. Open a project in the desktop app Code tab.
2. Send a prompt that takes more than ~10 seconds (e.g. "wait 10 seconds, then reply").
3. While Claude is working, type any message and press Enter.

Reproduces every time.

### Claude Model

Not sure / Multiple models

### Is this a regression?

Yes, this worked in a previous version

### Last Working Version

Unknown. Queueing worked until roughly early September 2026; I don't know which app version I had then. Current broken version: desktop app 1.49585.0.0 with bundled Claude Code 2.1.260.

### Claude Code Version

2.1.260 (bundled in desktop app 1.49585.0.0); standalone CLI on the same machine is 2.1.126 and is not affected.

### Platform

Anthropic API

### Operating System

Windows

### Terminal/Shell

Windows Terminal

### Additional Information

_No response_

Start by reproducing the regression in the Windows desktop app Code tab with a prompt that runs for more than 10 seconds, then compare its Enter behavior with the working CLI behavior and the related issues #57497, #66310, and #71726. Done means Enter queues the typed message until the current turn ends without interrupting it, or the desktop app provides an explicit queue key.

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