Cowork session storage resolves through redirected AppData\Roaming (UNC path) even after reinstall, breaking sandbox operations entirely

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's session storage (local-agent-mode-sessions/<session>/outputs and related paths) is written under %APPDATA%\Claude\... On a Windows domain machine where %APPDATA% is redirected to a network share via Folder Redirection GPO (a standard, common configuration in enterprise/AD environments), every Cowork session fails immediately with:

UNC paths are not supported: \\<server>\<share>\...\outputs

This is not limited to workspace folders the user selects manually. It happens regardless, because it's Cowork's own internal session directory, not a user-chosen path. Mapping the network share to a drive letter for the actual workspace folder has no effect, since the failure is in Cowork's internal session/output storage, not the user-selected folder.

The sandbox layer that backs Cowork's document-processing skills hits a hard categorical block on any UNC path, so no session can complete on a machine with a redirected AppData profile.

I fully uninstalled and reinstalled Claude Desktop before filing this, with no change in behavior. This is expected: where %APPDATA% resolves is controlled by the domain's Folder Redirection policy via the User Shell Folders registry key, entirely outside the application. A reinstall doesn't change that resolution, so the app writes to the same redirected location every time regardless of version.

A related existing issue documents a similar but distinct failure mode when AppData is redirected to a different local drive letter (not a network share), causing cross-device rename errors and VM boot failures: https://github.com/anthropics/claude-code/issues/37754

Separately, Anthropic's own documentation for Claude Desktop (3P) confirms that a very similar fix was already made for general app data: earlier releases stored data under %APPDATA% (Roaming), and the app now migrates this to %LOCALAPPDATA% automatically on first launch after upgrade, with explicit handling for the case where Roaming is redirected to a network share. Cowork's session storage does not appear to have received the same fix.

What Should Happen?

Cowork session storage that is inherently machine-local (temp working files, sandbox VM state, output staging) should live under %LOCALAPPDATA%, not %APPDATA%\Roaming. This matches Microsoft's own guidance that Roaming is for small, portable config data meant to sync between machines, while Local is for machine-specific state, and would sidestep Folder Redirection entirely for the vast majority of enterprise domain setups (AppData\Local is rarely redirected; Roaming is the one redirected, precisely because it's meant to roam).

At minimum, Cowork should not hard-fail with an opaque UNC error when AppData is redirected; it should either work transparently against the redirected path, or fall back to a local-only location and warn the user clearly about why.

Error Messages/Logs

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UNC paths are not supported: \\svr1.ahfp.local\userdata$\FolderRedirects\pwood\Application Data\Claude\local-agent-mode-sessions\4ebb755e-0fd2-4a4e-8c5e-96047e1a11b0\a2ff2be7-3c31-4951-8a12-9bc294e7684d\local_3f80a0f5-52c3-4b81-b088-fbb2bd203da7\outputs

Steps to Reproduce

1. On a Windows domain machine, configure Folder Redirection GPO so the user's AppData\Roaming (shown as "Application Data" in the redirected path) is redirected to a network share, e.g. \\<server>\<share>\FolderRedirects\<user>\Application Data
2. Open Claude Desktop and start a new Cowork session
3. Ask Cowork to do anything that writes session output
4. Cowork fails immediately with: UNC paths are not supported: \\<server>\<share>\...\Claude\local-agent-mode-sessions\...\outputs
5. Fully uninstall and reinstall Claude Desktop
6. Start a new Cowork session again
7. Same failure occurs, because %APPDATA% still resolves to the same redirected network path (this is controlled by domain GPO/registry, not the app installation)

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude 1.20186.0 (d7731e) 2026-07-09T06:13:11.000Z

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Not a duplicate of #45297 as this prevents cowork working at all, not just in a specific folder.