Last message in conversation can disappear

Description

The last message in a conversation can sometimes disappear unexpectedly.

Steps to reproduce

1. Have a conversation with Claude Code
2. Send a message
3. The last message may disappear from the conversation

Expected behavior

All messages should persist in the conversation history.

Actual behavior

The last message in the conversation can vanish.

Environment

• OS: macOS (Darwin 24.6.0)
• Claude Code version: latest