Bug: Input becomes unresponsive after tab switching during response generation

Environment

• OS: macOS (Darwin 24.6.0)
• Terminal: iTerm2
• Claude Code Version: 2.1.29

Steps to Reproduce

1. Run claude in an iTerm2 tab
2. Send a prompt and wait for response (spinner visible)
3. Switch to another iTerm2 tab while Claude is generating response
4. Switch back to the Claude tab
5. Try to type input

Expected Behavior

Input should work normally after returning to the tab.

Actual Behavior

• Initially: No characters appear when typing
• After stty sane: Characters appear but Claude doesn't respond to Enter/input
• Process appears healthy (S+ state, stdin connected to tty)
• Only fix is to kill the process

Additional Context

• Happens repeatedly (not a one-time issue)
• Process shows no network connections when stuck
• kill -SIGWINCH and stty sane don't restore functionality
• Suspect stdin polling stops when tab loses focus during response generation