[BUG] Cowork VM guest never connects on Windows ARM64 (Snapdragon) — timeout after add_plan9_shares

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 VM fails to start on Windows ARM64 (Snapdragon). All host-side boot steps complete successfully (vm_boot, add_plan9_shares), but the Linux guest OS never responds. The host waits 60 seconds for a vsock/guest connection that never comes, then times out. This happens consistently on every attempt, including after reboot and bundle deletion.

What Should Happen?

Cowork workspace starts successfully and accepts input.

Error Messages/Logs

2026-04-02 07:10:51 [VM:steps] vm_boot completed (82ms)
2026-04-02 07:10:51 [VM:steps] add_plan9_shares completed (3ms)
2026-04-02 07:11:01 [VM:start] Still waiting for guest connection... 10217ms elapsed
2026-04-02 07:11:12 [VM:start] Still waiting for guest connection... 20385ms elapsed
2026-04-02 07:11:22 [VM:start] Still waiting for guest connection... 30519ms elapsed
2026-04-02 07:11:32 [VM:start] Still waiting for guest connection... 40736ms elapsed
2026-04-02 07:11:42 [VM:start] Still waiting for guest connection... 50940ms elapsed
2026-04-02 07:11:51 [VM:start] Connection timeout, last completed step: add_plan9_shares
2026-04-02 07:11:51 [VM:start] Startup failed: Error: VM connection timeout after 60 seconds

Steps to Reproduce

1. Install Claude Desktop (v1.2.234.0 arm64) on Windows 11 ARM64 (Snapdragon)
2. Open Claude Desktop
3. Click the Cowork tab
4. Observe spinner for 60 seconds
5. Error appears: "Failed to start Claude's workspace — VM connection timeout after 60 seconds"

Note: Happens on every attempt. Reboot and bundle deletion do not help.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

1.2.234.0 arm64

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

This is a Cowork-specific issue, not Claude Code CLI. The VM bundle is fully downloaded and present (vmlinuz, initrd, rootfs, smol-bin.arm64.vhdx all exist). VirtualMachinePlatform is enabled. The host-side Hyper-V steps all complete successfully, but the Linux guest kernel never initializes. Related issues: #40198, #25474.