Cowork macOS: VirtioFS mount fails with 'operation not permitted' for home directory

Bug Report — Cowork VirtioFS Mount Failure (macOS)

Environment

• OS: macOS Sonoma (Darwin 23.4.0)
• Claude Desktop: v1.1.4328
• Cowork VM SDK: v2.1.51
• Docker Desktop: v28.0.1 (running, verified working)
• Full Disk Access: granted to both Claude + Docker

Error

RPC error: failed to mount ../nathasit as nathasit: source path does not exist and could not be created: /mnt/.virtiofs-root/nathasit: mkdir /mnt/.virtiofs-root/nathasit: operation not permitted

Steps to reproduce

1. Open Claude Desktop → Cowork tab
2. Create or open any task
3. Error appears immediately — "This task didn't load properly"

What was tried (all failed)

1. Docker Desktop running + verified Docker volume mounts work fine (docker run -v /Users/nathasit:/test alpine ls /test succeeds)
2. Full Disk Access enabled for Claude + Docker in System Settings → Privacy & Security
3. VM reset (deleted claudevm.bundle from ~/Library/Application Support/Claude/vm_bundles/) — worked temporarily, error returns after a few minutes
4. Restart Claude Desktop — no effect
5. Created new Cowork task — same error

Suspected cause

The relative path ../nathasit resolves incorrectly inside Cowork's own VirtioFS layer. Docker volume mounts work perfectly, so the issue is specific to Cowork's VM, not Docker Desktop.

Note: Home directory is /Users/Nathasit ($HOME uses capital N) but the actual folder name is lowercase nathasit. This case mismatch may confuse the VirtioFS path resolution.

Expected behavior

Cowork should be able to mount the user's home directory and load tasks normally.