[BUG] @mentioning files doesn't autocomplete for files with spaces in the filename

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?

When I @mentioning files in claude code in the desktop app, it doesn't autocomplete for files with spaces in the filename.

In claude code in the cli, I can do @"My file with spaces" and it will autocomplete.

In claude code in the desktop app, I can get autocompletion for @My but as @My closes the autocomplete. Using double quotes with @mentions in the desktop app does not work at all.

The is less an issue for software coding use cases where the convention is usually not have spaces in file names. But for other use cases such as obsidian.md interaction, spaces in filenames are common.

What Should Happen?

In claude code desktop I should be able to @"My file with spaces" and it will autocomplete.

Error Messages/Logs

Steps to Reproduce

In claude code in the desktop app, try to @mention a file with spaces in the filename.

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Claude 1.9659.4 (8cc655) 2026-06-02T02:30:57.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_