[BUG] Claude Code silently exits mid-task when running multiple concurrent sessions (Windows)

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?

Claude Code v2.1.71 (Opus 4.6) silently exits back to the command line while actively processing a task. There is no error message, no crash report, and no warning - the session just dies and returns to the shell prompt. This happens when running 3 concurrent Claude Code sessions, but it's unclear whether concurrency is required to trigger it.

The session appears to be mid-execution (shows "esc to interrupt" and active token count), then silently drops back to the CLI. Restarting with claude starts a fresh session with 0 tokens and no awareness of the previous context.

What Should Happen?

Claude Code should either:

1. Complete the task it was actively working on, OR
2. Display a meaningful error/warning before exiting (e.g., rate limit, memory, connection lost), OR
3. At minimum, provide a --resume session ID so work isn't lost

Error Messages/Logs

Steps to Reproduce

1. Open 3 separate terminal windows, each in a project directory
2. Launch claude in each terminal
3. Give each session a substantial task (e.g., implementation plan + execution)
4. Wait - one or more sessions will silently exit mid-task with no error output

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

n/a

Claude Code Version

2.1.71 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

<img width="1279" height="430" alt="Image" src="https://github.com/user-attachments/assets/24a5602c-7956-4bf7-8656-e18a03b96ffe" />