[BUG] VM workspace download loop — rootfs.vhdx download always times out (China, enterprise gateway)

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### Environment

• OS: Windows 11 Home China 10.0.26200
• Claude Desktop: 1.9659.2 (also reproduced on 1.9255.0)
• Claude Code: 2.1.156
• Platform: win32 x64
• Network: enterprise gateway (custom-3p provider: gateway)

### Description
The VM workspace never starts —"Workspace still starting" hangs indefinitely. The root cause is that rootfs.vhdx
cannot be downloaded. The app enters an infinite loop: download →timeout →auto-reinstall →delete bundle →download
again →timeout...

### Steps to reproduce

1. Install Claude Desktop on Windows 11 Home China
2. Open the app
3. Observe "Workspace still starting" never completes

### Expected behavior
VM workspace starts within ~1 minute after rootfs.vhdx download completes.

### Actual behavior
The download of rootfs.vhdx consistently fails with network errors. The bundle directory
(%LOCALAPPDATA%\Claude-3p\vm_bundles\claudevm.bundle) remains empty (0 bytes).

### Errors from cowork_vm_node.log
All download attempts fail within 20-30 seconds:

• ERR_CONNECTION_TIMED_OUT (most frequent)
• ERR_CONNECTION_RESET
• ERR_CONNECTION_CLOSED
• ERR_TIMED_OUT
• ERR_NETWORK_CHANGED

Sample log entries:
rootfs.vhdx not found, downloading...
Downloading rootfs.vhdx...
[error] [VM:start] Startup failed: Error: Request error: net::ERR_CONNECTION_TIMED_OUT
[VM:start] Auto-reinstalling workspace after startup failure
[deleteVMBundle] Reinstall files deleted

This cycle repeated 30+ times over 2 days without success.

### Additional context

• Bundle version: 5680b11bcdab215cccf07e0c0bd1bd9213b0c25d
• vm_bundles folder: 0 bytes, only .auto_reinstall_attempted present
• claude-code-vm folder: 230MB (incomplete)
• No proxy/VPN was active during most attempts
• This CLI version of Claude Code works fine —only the desktop app's VM sandbox is affected

### Workaround attempted

• Clearing cache, rebooting, reinstalling —no effect
• The download server appears unreachable from this network environment

### Suggestion
Provide an offline/alternate download source for rootfs.vhdx, or add a longer timeout with retry with backoff. The
current 20-30s timeout is insufficient for multi-GB downloads on high-latency or throttled connections.

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