[BUG] @ mention and / command shortcuts fail when editing previous message

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?

Bug Description
When editing a previous message (navigating with ↑ key), both the @ symbol and / command
shortcuts fail to trigger their respective UI popups. Instead, they are inserted as plain text
characters. The shortcuts only resume working after clearing the input with ESC.

Environment

• Claude Code version: 2.1.72
• OS: macOS 26.3
• Chip: Apple Silicon M4
• Terminal: Ghostty (also reproduced in Terminal.app)

What Should Happen?

@ and / should always trigger their respective popups, regardless of whether the user is
editing a previous message or composing a new one.

Error Messages/Logs

Steps to Reproduce

1. Start a Claude Code session
2. Send any message (e.g., "hello")
3. Press ↑ to navigate to the previous message for editing
4. Try to type @ or / anywhere in the message
5. Observe that both characters appear as plain text instead of triggering:

• @ → file picker popup
• / → command palette popup

1. Press ESC twice to clear the input
2. Type @ or / again — both shortcuts now work correctly

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.72

Platform

Other

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• This appears to be a TUI state management issue where the key handlers for @ and / are not

properly registered when transitioning to "edit previous message" mode

• Reproduced across multiple terminals (Ghostty, Terminal.app), suggesting it's not

terminal-specific

• Both shortcuts are affected, indicating a systemic issue with input mode state handling