[BUG] [BUG] Cowork workspace fails with false "Download failed" on Windows MSIX 1.11187.4 — VM files validate OK but download_and_sdk_prepare throws before smol-bin copy step

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?

After auto-updating to Claude Desktop 1.11187.4 (Windows MSIX/Store install), Cowork workspace fails to start on every launch with the UI error "Failed to start Claude's workspace — Download failed. Check your internet connection and try again."
This is a false error. The log shows all three VM bundle files (rootfs.vhdx, vmlinuz, initrd) are downloaded/decompressed and checksum-validated successfully, "All files ready" is logged, and then download_and_sdk_prepare immediately throws "Download failed" on the very next line. It is not a network issue.

What Should Happen?

When all VM bundle files are present and checksum-validated, the workspace should proceed past download_and_sdk_prepare and launch — not throw a false "Download failed."

Error Messages/Logs

Steps to Reproduce

This is a regression introduced today (June 5–6, 2026). Same machine, same network, comparing log entries by app version:

1.9659.2.0 (Jun 5, 12:21) — ✅ works: download_and_sdk_prepare completed → smol-bin.x64.vhdx copied successfully → Network status: CONNECTED → sdk_install completed
1.11187.1.0 (Jun 5, 15:18) — ✅ works (last good run, identical successful sequence)
1.11187.4.0 (Jun 6, all runs) — ❌ fails: never gets past download_and_sdk_prepare; the next step (Copying smol-bin.x64.vhdx) is never reached

Key evidence: In 1.11187.4.0, no run on June 6 ever logs create_network, sdk_install, or Network status — it dies inside download_and_sdk_prepare right after "All files ready", strongly suggesting the failing operation is the post-files-ready step (the smol-bin.x64.vhdx copy from Program Files\WindowsApps\...\app\resources\ into the bundle), with the exception mislabeled as "Download failed."
Deleting the VM bundle, deleting the .auto_reinstall_attempted marker, full reinstall, and re-downloading all files from the network (not cache) do not help — files re-validate, then the same false "Download failed" recurs.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.11187.4 (584005) 2026-06-05T20:15:04.000Z

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_