[BUG] Cowork: VirtioFS mount fails with "operation not permitted" — all projects blocked, regression from previously-working state

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?

All Cowork projects fail to start with an RPC mount error. The error references a specific Live Artifact's scaffold folder, but moving, deleting, or recreating that folder does not resolve the issue — the VM continues attempting the same mount and failing on every project.

Cowork was working reliably until recently. No deliberate configuration changes were made on my end.

• All Cowork projects show ⚠️ warning indicator in sidebar
• Clicking into any project displays "Something went wrong" error block with the RPC error
• The error block offers "Go back" and "Try again" buttons; "Try again" produces the same error
• The Live Artifact "Monarch Health Dashboard" (which the error path references) continues to function correctly and processes CSV uploads — its scaffold folder appears to be unused at runtime

Troubleshooting attempted (none resolved the issue)

1. Moved the referenced folder (~/Documents/Claude/Artifacts/monarch-health-dashboard/) to a different location → same error
2. Recreated an empty folder at the original path → same error
3. Verified Claude Desktop is on latest version (1.4758.0) → same error
4. Searched Settings → Cowork, Settings → Claude Code, and project right-click menus for a "Reinstall workspace" or "Reset VM" option → no such option exists in the current UI
5. Quit and relaunched Claude Desktop multiple times → same error

What Should Happen?

Cowork projects should mount their associated folders and accept messages without RPC mount failures. The mount path should not collide with macOS system directories.

Error Messages/Logs

RPC error: failed to mount /mnt/.virtiofs-root/shared/Users/newkelly/Documents/Claude/Artifacts/monarch-health-dashboard as .artifacts/monarch-health-dashboard: source path is not accessible: /mnt/.virtiofs-root/shared/Users/newkelly/Documents/Claude/Artifacts/monarch-health-dashboard: stat /mnt/.virtiofs-root/shared/Users/newkelly/Documents/Claude/Artifacts/monarch-health-dashboard: operation not permitted


The critical phrase is **"operation not permitted"** on a path under `/mnt/.virtiofs-root/shared/`. This appears similar to the known case-collision issue with macOS `/Users/Shared/` (e.g. issue #29247), even though my macOS username is `newkelly`, not `shared`.

Steps to Reproduce

1. Open Claude Desktop
2. Click any Cowork project (in my case: "Dave Johnson, New Brooklyn Land")
3. Attempt to send any message in any task within the project
4. Mount error appears immediately

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.4758.0 (fb266c) 2026-04-24T20:22:30.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• I have substantial chat history in these projects that I'd prefer to preserve, so I have not attempted to delete ~/Library/Application Support/Claude/claude-code-vm/ as a destructive workaround.
• Happy to provide additional logs, screenshots, or system information if helpful.
• This is blocking my daily workflow — Cowork is part of my regular workflow for commercial leasing work.