[BUG] [Cowork] New project's local folder context fails to load - mcp__remote-devices__device_list_dir not registered in session

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?

After creating a brand-new Cowork project on Windows and attaching a local folder as context, Claude cannot read the folder even after the OS-level "Folder access request" permission dialog is approved (clicked Allow). Claude's own session output states the device bridge tool is not registered: it calls tool_search repeatedly for terms like "device_list_dir" and "remote-devices directory list files", and every call returns "No matching deferred tools found". The session ultimately reports: <tool_use_error>Error: No such tool available: mcp__remote-devices__device_list_dir</tool_use_error>. This happens even though the same environment previously supported full local file access in an older Cowork project (before the Jul 8 2026 Chat/Cowork merge - see related issue #75603).

What Should Happen?

After the folder access permission is granted, Claude should be able to list and read files in the connected local folder using an available device-bridge tool.

Error Messages/Logs

<tool_use_error>Error: No such tool available: mcp__remote-devices__device_list_dir</tool_use_error>

tool_search query "select:device_list_dir" -> "No matching deferred tools found"
tool_search query "remote-devices directory list files" -> "No matching deferred tools found"

Steps to Reproduce

1. On Windows, open Claude Desktop app (confirmed the desktop app and web/mobile session use the identical Claude account).
2. 2. Create a new Cowork project; folder location C:\Users\<user>\Documents\Claude\Projects\<project> (inside home directory; not OneDrive-synced - no cloud placeholder icons; cache/build folders totalled only ~4.22MB, ruled out as cause).
3. 3. Attach the folder to the project's context.
4. 4. Send a task, e.g. "컨텍스트에 연결된 폴더 확인해줘" (check the folder connected to context).
5. 5. A "Folder access request" OS-level permission dialog appears; click Allow.
6. 6. Claude still cannot access the folder. Internal tool_search calls for device_list_dir / remote-devices tools return "No matching deferred tools found".
7. 7. Already tried: fully quitting and restarting Claude Desktop; removing and re-adding the folder from the project context; re-approving the permission dialog - same error persists every time.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Local folder access worked in Cowork prior to the Jul 8, 2026 Chat/Cowork merge rollout (see related issue #75603)

Claude Code Version

N/A - reporting via Claude Desktop app (Cowork/Chat merged UI), not Claude Code CLI

Platform

Other

Operating System

Windows

Terminal/Shell

Other

Additional Information

Related issue: #75603 (existing local-folder project disappeared after the same Chat/Cowork merge). Both issues surfaced the same day the merge rolled out (Jul 8, 2026) and are likely connected to the same backend change. Happy to attach screenshots of the tool_search error trace and the Folder access request dialog if useful.