[BUG]

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?

In the Claude Code Desktop App, @-mention path autocomplete does not support incremental, segment-by-segment Tab completion the way the CLI does.
Specifically:

Typing @ opens the file suggestion dropdown correctly.
Pressing Tab does not complete the highlighted/first suggestion in place — instead, focus jumps out of the input entirely to the Send button.
Pressing Enter while the dropdown is open closes the dropdown instead of accepting the highlighted suggestion and allowing the user to keep typing.

As a result, there's no way to build a nested path (e.g. @folder/nested1/nested2/index.tsx) incrementally using Tab, like you can in the CLI (@fol → Tab → @folder/ → continue typing → Tab again, etc.). The only workaround is typing the full path manually or selecting one complete entry from the dropdown with arrow keys + Enter, which doesn't chain across path segments.

What Should Happen?

Pressing Tab while the @-mention dropdown is open should accept the currently highlighted suggestion and complete it in place (appending / for directories), the same way it does in the CLI. The input should remain focused and the dropdown should stay active for the next path segment, so the user can continue typing and pressing Tab to drill into nested folders — without focus ever jumping to another UI control like the Send button.
For example, given the path folder/nested1/nested2/index.tsx:
@fol → Tab → @folder/
nes → Tab → @folder/nested1/
nes → Tab → @folder/nested1/nested2/
ind → Tab → @folder/nested1/nested2/index.tsx
Enter should behave as a separate action from Tab — either submitting the message (if no dropdown is open) or, at minimum, not silently dismissing the dropdown without applying the highlighted suggestion.

Error Messages/Logs

Steps to Reproduce

Steps to Reproduce

Open the Claude Code Desktop App and open a project folder that contains a nested directory structure (e.g. folder/nested1/nested2/index.tsx).
In the chat input, type @fol (a partial match for folder).
Observe the file suggestion dropdown appears with folder highlighted/suggested.
Press Tab.
Observe that focus jumps to the Send button instead of completing the input to @folder/.
Retype @folder/nested1/nested2/index.tsx manually, then press Enter partway through (e.g. right after @folder) while the dropdown is still open.
Observe that Enter closes/dismisses the dropdown instead of accepting the highlighted suggestion.

Expected result: Tab completes the highlighted suggestion in place and keeps the input focused for continued typing/tabbing through nested segments.

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude 1.18286.0 (259c3f) 2026-07-02T07:11:03.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

Note: this bug is specific to the Claude Code Desktop App's native chat input, not the Claude Code CLI/terminal. The CLI's @-mention Tab completion already works as expected — this report is only about the Desktop App failing to replicate that same behavior.