[BUG] Cowork crashes with "Claude Code process exited with code 3" — Bun segfault inside VM on Windows 11 Enterprise

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?

Cowork fails on every attempt with Claude Code process exited with code 3. The VM starts successfully (startup completes in ~22 seconds), but Claude Code crashes immediately when a session is initiated. The root cause visible in the logs is a Bun runtime segfault inside the VM.

What Should Happen?

Environment

• OS: Windows 11 Enterprise (Build 26200)
• Claude Desktop version: 1.6259.1.0
• Claude Code (bundled): v2.1.128
• Windows Features enabled: Hyper-V ✅, VirtualMachinePlatform ✅, HypervisorPlatform ✅
• CoworkVMService: Running ✅
• Regular chat: Works fine — only Cowork is affected

Steps to Reproduce

1. Open Claude Desktop on Windows 11 Enterprise
2. Navigate to the Cowork tab
3. Start or resume any session
4. Error appears: "Claude Code process exited with code 3"

Relevant Log Output

From %LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\logs\main.log:

panic: Segmentation fault at address 0x2CE2278FFE8
panicked during a panic. Aborting.

[error] Session local_9dcb25a8-e9e1-477a-8617-db6c20a71ebf query error: Claude Code process exited with code 3

[CycleHealth] Unhealthy cycle:
  error_message: 'Claude Code process exited with code 3'
  error_category: 'process_crashed'
  unhealthy_reason: 'system_error'
  had_first_response: false
  model: 'claude-opus-4-7'

VM startup completes successfully before the crash:

[VM:start] Startup complete, total time: 21965ms
[VM] API reachability: REACHABLE
[VM:steps] sdk_install completed (4058ms)

### Error Messages/Logs

```shell

Steps to Reproduce

1. Open Claude Desktop on Windows 11 Enterprise
2. Navigate to the Cowork tab
3. Start or resume any session
4. Error appears: "Claude Code process exited with code 3"

Relevant Log Output

From %LOCALAPPDATA%\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\logs\main.log:

panic: Segmentation fault at address 0x2CE2278FFE8
panicked during a panic. Aborting.

[error] Session local_9dcb25a8-e9e1-477a-8617-db6c20a71ebf query error: Claude Code process exited with code 3

[CycleHealth] Unhealthy cycle:
  error_message: 'Claude Code process exited with code 3'
  error_category: 'process_crashed'
  unhealthy_reason: 'system_error'
  had_first_response: false
  model: 'claude-opus-4-7'

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.6259.1.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_