[BUG] Autocomplete UI view not working with any slash commands

Environment

• Platform (select one):
• [X] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: 0.2.73
• Operating System: macOS 15.4.1
• Terminal: iTerm2

Bug Description

Autocomplete with local files feature is not working with any slash command, and tested with both built-in slash commands and also with project scope custom slash commands. After press TAB key, the suggest file list view flash for a second then disappeared.

In the same CC session, bash command with ! works fine with the autocomplete.

Please see the attached video recording session.

Steps to Reproduce

1. after any slash command, then try to append with any prefix which matches some local file names under the current CC context directory.
2. keep pressing the TAB key, you will see the quick flash of suggested filename autocomplete view, then disappeared.

Expected Behavior

The autocomplete feature should also work with slash commands, especially it would be very useful to work with user/project custom slash commands with $ARGUMENTS scenario.

Actual Behavior

The UI defect with the slash command cause the feature is not available for slash commands

Additional Context

https://github.com/user-attachments/assets/c3b64a5a-8a84-4229-91ba-06518b11796b