[BUG] Keystrokes typed during startup are not captured

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?

Keystrokes typed while Claude Code is starting up are not being captured, despite the v2.1.10 release notes stating "Improved startup to capture keystrokes typed before the REPL is fully ready."

The observed behavior:

1. Type claude and press Enter
2. Immediately start typing additional input
3. Characters appear briefly on the terminal
4. After about a second, buffer stops accepting any more characters, and pauses for a bit before the claude UI shows up.
5. Claude Code REPL starts with an empty buffer - none of the typed input was captured

What Should Happen?

Keystrokes typed after pressing Enter (while Claude Code is loading) should be captured and appear in the input buffer once the REPL becomes ready, as described in the v2.1.10 release notes.

Video reproduction

https://github.com/user-attachments/assets/ad544e8b-c442-4b91-adee-b19116d4261f

Error Messages/Logs

Steps to Reproduce

1. Open a terminal
2. Type claude and press Enter
3. Immediately start typing (e.g., "hello world")
4. Observe the REPL starts with an empty input buffer

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

2.1.11 (Claude Code)

Claude Code Version

2.1.11 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

The v2.1.10 release notes specifically mention:

"Improved startup to capture keystrokes typed before the REPL is fully ready"

This feature does not appear to be working. The terminal briefly shows typed characters, then stops displaying them, and the REPL starts with no captured input.