[BUG] Cowork VM guest connection timeout on ARM64 Windows (Snapdragon X Plus) - never connects

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 has never worked on this machine. The VM downloads, boots, and completes all startup steps successfully, but the guest OS never establishes a connection back to the host. Times out at exactly 60 seconds every time. This is 100% reproducible across 4+ attempts including full workspace reinstalls.
Claude Chat and Claude Code both work perfectly on the same machine.
Related issues: #43452 (Plan9 share failure on Windows), #43915 (Cowork silent fail on Windows Build 26200), #28231 (CoworkVMService failure on Build 26200)
Environment

Device: Lenovo IdeaPad Slim 5 (model 83HL)
Processor: Qualcomm Snapdragon X Plus (ARMv8, ~3244 MHz)
RAM: 32GB
OS: Windows 11 Pro ARM64, Build 26200
Claude Desktop: 1.1617.0 ARM64 MSIX (Microsoft Store)
Hyper-V: Enabled (all features)
Virtual Machine Platform: Enabled
Windows Hypervisor Platform: Enabled
Virtualization-based security: Running

What works

Claude Chat ✅
Claude Code ✅ (local sessions, fully functional)
Hypervisor detected and running ✅

What doesn't

Cowork ❌ — never worked, not once
Fails with and without projects
Fails on any folder (tested multiple)

What Should Happen?

Cowork workspace should start and accept tasks.

Error Messages/Logs

Failure pattern from cowork_vm_node.log
Every attempt follows the same sequence:
[VM:steps] download_and_sdk_prepare completed
[VM:steps] load_swift_api completed (0ms)
[VM:start] smol-bin.arm64.vhdx copied successfully
[VM:start] Windows VM service configured
[VM:steps] create_network completed
[VM:steps] create_vm_config completed
[VM:steps] vm_boot completed (1423ms)
[VM:steps] add_plan9_shares completed (16ms)
[VM:start] Still waiting for guest connection... 10313ms elapsed, 21 polls
[VM:start] Still waiting for guest connection... 20553ms elapsed, 41 polls
[VM:start] Still waiting for guest connection... 30773ms elapsed, 61 polls
[VM:start] Still waiting for guest connection... 40899ms elapsed, 81 polls
[VM:start] Still waiting for guest connection... 51087ms elapsed, 101 polls
[VM:start] Connection timeout, last completed step: add_plan9_shares
Dispatching startup error: VM connection timeout after 60 seconds
[VM:start] Startup failed: Error: VM connection timeout after 60 seconds
The VM boots in ~1.4 seconds, all steps complete, but the guest never connects. Auto-reinstall triggers, deletes and re-downloads the bundle, and the same failure repeats.
Later attempts also show repeated SDK install timeouts:
[postConnect] Installing SDK: subpath=c/Users/cam/AppData/Local/Packages/Claude_pzs8sxrjxfjjc/LocalCache/Roaming/Claude/claude-code-vm, version=2.1.92
[startVM] Post-connect setup failed on already-connected fast path: Error: request timed out after 30s

Steps to Reproduce

Install Claude Desktop from Microsoft Store on ARM64 Windows 11 Pro
Open Cowork tab
Enter any prompt
Observe "Starting Claude's workspace..." spinner
Wait 60 seconds for timeout

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

v2.1.91

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Troubleshooting already done

Multiple full workspace reinstalls
Confirmed Hyper-V, Virtual Machine Platform, HypervisorPlatform all enabled
Confirmed virtualization-based security running via systeminfo
Tested with different folders and with/without projects
Claude Code works perfectly on same machine (hypervisor is functional)
Verified via Anthropic support chat — they confirmed all client-side settings are correct and escalated to engineering