[Cowork] Local device bridge (device_bash/device_stage_files) broken on Windows after 2026-09-08 update — blocks file/network access on multiple machines

### 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 sessions that use the local device bridge (device_bash, device_list_dir, device_stage_files) on Windows 11 can no longer reliably access the local filesystem / mapped network shares on the user's PC. This has been reproduced independently on at least two different physical machines in the same office (different Windows user accounts), both correlating with a Windows update released around 2026-09-08.

Case 1 (machine "pcbim2"): a Cowork session using device_bash needed to run a Python script that reads/writes a file on a mapped network share (Z:\). The session reported the local shell as unreachable, explicitly attributing it to a known issue tied to the 2026-09-08 Windows update, and this blocked every command issued through that tool for the rest of the session.

Case 2 (second, independent PC, different Windows user account): in a Cowork session, device_stage_files used a different path than the one returned by device_list_dir for the same file, so staging failed even though the file was visible in the directory listing. The session explicitly reported that both local shell execution and direct file loading were failing due to a problem tied to the 2026-09-08 Windows update that is blocking the bridge to local files.

In both cases the affected files/folders were visible in directory listings but could not be executed against or loaded into the Cowork environment.

### What Should Happen?

The device bridge (device_bash / device_list_dir / device_stage_files) should be able to mount/access the same local files and mapped network shares it could access before the 2026-09-08 Windows update, on both affected machines, consistently.

### Error Messages/Logs

```shell
Case 1 (device_bash, pcbim2): "la connessione remota al tuo PC che al momento non monta le cartelle condivise" — reported as a known issue tied to a Windows update from 2026-09-08, blocking all commands from that session.

Case 2 (device_stage_files, second PC): "File esiste, il problema è che device_stage_files usa un path diverso da quello mostrato in device_list_dir. Riprovo con lo stesso path esatto restituito da list_dir (che ha funzionato per list_dir)." Followed by: local shell execution and direct file loading both fail for a known problem tied to a Windows update from 2026-09-08, blocking the bridge to local files; files show in the listing but cannot be executed or loaded into the environment.
```

### Steps to Reproduce

1. On a Windows 11 Pro machine that has installed the Windows update from around 2026-09-08, open a Claude Cowork session.
2. Point the session at a project folder that lives on a mapped network share (e.g. Z:\ mapped to a network drive), or any local folder, and ask it to run a local command via device_bash, or to read/stage a file via device_list_dir / device_stage_files.
3. Observe that device_bash reports the local shell/connection as unreachable, or that device_stage_files fails to stage a file whose path was just returned successfully by device_list_dir.
4. Files/folders remain visible in directory listings, but no command can be executed and no file can be loaded into the Cowork environment for the rest of the session.
5. Repeat on a second, independent Windows 11 machine (different user account) — same symptom class occurs.

Note: this is a Cowork-session-specific issue. A plain Claude Code CLI/session on the same machine, not going through the device bridge, can access the same files/shares without problems.

### 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

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 above since neither list covers the Cowork desktop app). The affected feature is the local device bridge the Cowork app uses to give a session access to the user's own PC (local shell + local/network files).

Both affected machines are on the same office network, Windows 11 Pro build 10.0.26100. A separate, unaffected Claude Code session on one of the same machines (not going through the Cowork device bridge) could access the same network share and run the same script without any problem — which is why we believe this is specific to the device-bridge/sandbox provisioning mechanism rather than a general Windows/network permissions issue.

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

Start by reproducing the Cowork local device bridge failure on Windows 11 build 10.0.26100 after the update around 2026-09-08, covering device_bash, device_list_dir, and device_stage_files. Compare the bridge with a plain Claude Code CLI session on the same machine and collect the relevant logs; done means local files and mapped network shares are consistently accessible through all three bridge operations.

Scritto dal modello di indicizzazione a partire dal testo della issue.