[BUG] Lost unsent message

Environment

• Platform (select one):
• [x] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: 1.0.35 (Claude Code)
• Operating System: Debian Linux 13
• Terminal: foot

Bug Description

Accidentally pressing <kbd>Up</kbd> with cursor on top line of unsent message results in the message loss.

Steps to Reproduce

1. Start typing an elaborate instruction in a long chat
2. Position cursor on the first line
3. Press <kbd>Up</kbd>
4. Despair

Expected Behavior

The message is preserved.

Actual Behavior

The message is lost.

Additional Context

Might consider requiring <kbd>Shift+Up</kbd> or similar to go back if text input is non-empty.