[BUG] device_bash / Cowork local device bridge fails on Windows 10 (10.0.19045) — same symptom as #94266/#92958, but NOT Windows 11

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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's local device bridge (device_bash) fails consistently on a Windows 10 Pro machine, reporting the identical error message used for the known Windows-11 "September 8 update" issue (#94266, #92958) — but this machine is Windows 10 Pro, build 10.0.19045 (22H2), not Windows 11. Either the same underlying bug also affects Windows 10, or the error message is misattributing an unrelated Windows 10 failure to that specific Windows 11 incident.

device_list_dir, device_stage_files, and device_commit_files all work fine against the same connected folder — only device_bash (shell/command execution) fails.

### What Should Happen?

device_bash should be able to run shell commands (e.g. git) on this machine the same way it can via device_list_dir etc., or if Windows 10 is genuinely unsupported/out of scope for the fix, the error message should say so instead of citing a Windows-11-specific update that this OS will never receive.

### Error Messages/Logs

```shell
Two error variants seen on the same machine, both containing the line: "A Windows update released September 8 prevents Claude's workspace from reaching your files. We're tracking this issue. Claude Code is unaffected."

1) sandbox-helper: no Plan9 drive shares mounted under /mnt/.virtiofs-root/shared
[Note: mnt/ failed to mount and cannot be reached from this shell. Those connected folders are still reachable via device_list_dir / device_stage_files / device_commit_files, by their paths on this device.]

2) Workspace unavailable. The isolated Linux environment on this device failed to start. Use device_stage_files / device_commit_files instead.
```

### Steps to Reproduce

1. On a Windows 10 Pro (build 19045) machine, open a Cowork session with a folder connected via the device bridge.
2. Call device_bash with any command (e.g. echo test).
3. Observe the error above, attributing the failure to a Windows-11-specific September 8 update that does not apply to this OS version.
4. device_list_dir / device_stage_files / device_commit_files against the same folder succeed normally.
5. Restarting the Claude desktop app: no change. Full OS reboot: briefly reports "Workspace still downloading," then reverts to the same failure.

### Claude Model

None

### Is this a regression?

Yes, this worked in a previous version

### Last Working Version

_No response_

### Claude Code Version

1.52386.6

### Platform

Other

### Operating System

Windows

### Terminal/Shell

Other

### Additional Information

Device: HP ProBook 640 G2, DESKTOP-8V*****. This is a Claude Cowork desktop session (not the Claude Code CLI, and not a direct Anthropic API integration — selected "Other" for Platform and "Other" for Terminal/Shell since neither list covers the Cowork desktop app).

Anthropic's Cowork changelog documents this class of failure as fixed by Microsoft's KB5129195, but that patch targets Windows 11 24H2/25H2 only — it has no Windows 10 equivalent, so this machine can't be "fixed" by that update. Flagging this as a distinct data point from #94266/#92958, both of which are Windows 11 Pro build 10.0.26100.

Happy to provide further logs or a live repro session if useful.

Start by reproducing device_bash with a simple command such as echo test on Windows 10 Pro build 19045, then compare it with device_list_dir, device_stage_files, and device_commit_files on the same connected folder. Done means device_bash works on this Windows version, or its error accurately describes the supported platform and failure instead of citing a Windows 11-only update.

Written by the indexing model from the issue text.