[BUG] Built-In [Filesystem] MCP Server in 1.1.9310 crashes on startup

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?

Issue: The built-in [Filesystem] MCP server introduced in 1.1.9310 crashes on startup with an unexpected transport close. The manually configured [filesystem] entry works correctly and is unaffected.
Key log evidence:
2026-03-27T20:54:29.035Z [Filesystem] [info] Using built-in Node.js for MCP server: Filesystem
2026-03-27T20:54:33.743Z [Filesystem] [info] Server transport closed unexpectedly,
this is likely due to the process exiting early.
2026-03-27T20:54:33.743Z [Filesystem] [error] Server disconnected.
What's working: The user-configured filesystem MCP server (via claude_desktop_config.json) initializes successfully and functions normally.

What Should Happen?

The user-configured filesystem MCP server (via claude_desktop_config.json) initializes successfully and functions normally. The new built-in Filesystem server should also initialize successfully. No stderr output exists, so would this be a MSIX sandbox issue?

Error Messages/Logs

2026-03-27T20:54:29.035Z [Filesystem] [info] Using built-in Node.js for MCP server: Filesystem
2026-03-27T20:54:33.743Z [Filesystem] [info] Server transport closed unexpectedly, 
  this is likely due to the process exiting early.
2026-03-27T20:54:33.743Z [Filesystem] [error] Server disconnected.

Steps to Reproduce

1. Install or update Claude Desktop to 1.1.9310 (cb30ac) on Windows via MSIX.
2. Have an existing filesystem entry in claude_desktop_config.json pointing to OneDrive-backed paths.
3. Launch Claude Desktop.
4. Observe [Filesystem] (built-in) crashes on startup while [filesystem] (user-configured) succeeds.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.1.9310 (cb30ac)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_