[BUG] CoWork: request_cowork_directory tool call silently hangs — never returns success or failure

Description

When a CoWork session calls the request_cowork_directory tool to mount a user folder, the tool call silently hangs. No success, no failure, no UI prompt appears (or if it does, the response never reaches the assistant). The turn dies with no output, identical to the silent Edit failure on read-only mounts.

Steps to Reproduce

1. Open a CoWork session in Claude Desktop on Windows
2. Ask Claude to mount a folder (e.g., an outputs directory)
3. Claude calls request_cowork_directory with the target path
4. The turn silently dies — no response, no folder picker dialog, no error

This was reproduced 3 consecutive times in the same session. Each attempt produced zero output to the user.

Expected Behavior

Either:

• A folder picker dialog appears for the user AND the tool returns success/failure to the assistant, OR
• If the tool cannot prompt the user (e.g., UI context not available), it returns an error message so the assistant can fall back to manual instructions

Actual Behavior

The tool call never returns. The assistant's turn ends silently. The user has to manually realize what happened and mount the folder through the CoWork UI themselves.

Impact

This creates a chicken-and-egg problem:

• The most important CoWork optimization (mounting a workspace folder for direct file I/O) requires this tool
• But the tool silently fails, making it impossible to automate
• Users must discover the manual folder mount path on their own
• Combined with the Edit-on-read-only-mount hang (separate issue), a single session can have 5+ "stuck" episodes, destroying user trust

Environment

• Claude Desktop v1.1617.0 (Windows, MSIX)
• CoWork VM bundle version: 5680b11bcdab215cccf07e0c0bd1bd9213b0c25d
• claude-code-vm SDK: 2.1.92
• Windows 11 Pro

Workaround

Tell the user to manually mount the folder through the CoWork UI sidebar. Document this in CLAUDE.md with instructions to never call request_cowork_directory until this bug is fixed.

Related Issues

• #25797 (request_cowork_directory missing from session — different bug, same tool)
• #33564 (AskUserQuestion tool fires but cards don't render — similar pattern of tool-to-UI communication failure)