[BUG] Cowork: No working stop mechanism; deleting task to stop it permanently deleted user files; usage consumed despite malfunction

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?

Windows version: 11 Home; Claude Desktop; Date of incident: 10 Jun 2026. A Cowork task ran for several hours without completing. There was no working mechanism to stop it. Typing messages into the chat did not interrupt the task. Closing the Claude Desktop app repeatedly did not stop the background process. The only available option was to delete the task. Deleting the task permanently deleted my files.

Steps that led to this

Started a Cowork task -- [brief description of what the task was]
Task ran for several hours with no completion
Typing stop instructions into chat had no effect
Closing the app multiple times did not stop the process
Deleted the task as the only remaining option
Files were permanently deleted as a result

Expected behavior

A visible, working stop button during task execution
Deleting a task should not delete user files without an explicit warning and confirmation
A malfunctioning task should not consume plan usage

Actual behavior

No stop mechanism worked
Deleting the task deleted my files with no warning
Significant plan usage was consumed

Impact

Permanent file loss: [list the files or folders if you are comfortable doing so]
Plan usage consumed: [check claude.ai/settings/usage and note the amount]
Anthropic support declined to refund the usage

Related issues
This appears related to #32637, #30988, and #38055 which document similar file loss behavior in Cowork.

What Should Happen?

Patch Claude so this error does not repeat.

Error Messages/Logs

The log is too large to add, 85MB.

Steps to Reproduce

I uploaded 20 PDFs and asked Claude to verify the content and check for copyright violations.

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.11847.5.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_