[BUG] Cannot attach files from Google Drive mounted drive (G:) — EXDEV cross-device link error on Windows

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?

<img width="735" height="295" alt="Image" src="https://github.com/user-attachments/assets/089357ac-36b7-4fc3-98a5-697a5fba5be2" />

Describe the bug: When attaching a PDF file from a Google Drive mounted drive (G:) in Claude Desktop (Cowork), the attachment fails with an EXDEV cross-device link error. Image files from the same G: drive location attach and display correctly.

Error message:
EXDEV: cross-device link not permitted, link 'G:\My Drive\Business\Enigma\Decks - Enigma\Enigma Jamaica Deck Update Q4 2025\Enigma Jamaica Investor Deck - Q4 2025.pdf' ->
'C:\Users\sdcat\AppData\Roaming\Claude\local-agent-mode-sessions\[session-id]\uploads\Enigma Jamaica Investor Deck - Q4 2025.pdf'

Root cause hypothesis:
Images are embedded as base64 directly into the conversation — no filesystem operation required. PDFs are handled differently: Cowork attempts to create a hard link from the G: source path to a local session uploads folder on C:. Windows does not permit hard links across different drive letters. The fix is to use fs.copyFile() instead of fs.link() in the PDF upload handler when source and destination are on different devices.

What Should Happen?

Expected behavior:
PDFs from G: drive attach successfully, consistent with image behavior.

Error Messages/Logs

EXDEV: cross-device link not permitted, link 'G:\My Drive\Business\Enigma\Decks - Enigma\Enigma Jamaica Deck Update Q4 2025\Enigma Jamaica Investor Deck - Q4 2025.pdf' ->
'C:\Users\sdcat\AppData\Roaming\Claude\local-agent-mode-sessions\[session-id]\uploads\Enigma Jamaica Investor Deck - Q4 2025.pdf'

Steps to Reproduce

Steps to reproduce:

1. Mount Google Drive via Google Drive for Desktop (appears as G: on Windows)
2. Open Claude Desktop (Cowork)
3. Attempt to attach a PDF file from G:\My Drive...
4. Observe EXDEV error and "Something went wrong" message
5. Attempt to attach an image file from the same G: location — succeeds without error

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Desktop version: v2.1.92

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

Related issue: #44407 — Google Drive connector "not connected" state after disconnect/reconnect cycle. This EXDEV error was encountered as a workaround attempt when the native connector was unavailable.