[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
• [x] I am using the latest version of Claude Code

What's Wrong?

Keystrokes typed while Claude Code is starting up are lost. The REPL starts with an empty buffer despite input being typed immediately after running claude.

This was previously reported in #18779 (closed as not planned).

Steps to Reproduce

1. Type claude and press Enter
2. Immediately start typing
3. REPL starts with empty input buffer — typed characters are lost

What Should Happen?

Typed input should be captured and appear in the buffer once the REPL is ready.

Platform

macOS

Claude Code Version

Latest