[BUG] ^[[I sequence appears in VSCode terminal on startup

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?

When launching Claude Code in VSCode's integrated terminal, the literal string ^[[I appears on its own line before the Claude Code banner.

What Should Happen?

It should open the TUI normally.

Error Messages/Logs

Steps to Reproduce

Simply launching the claude command in the VSCode terminal seems sufficient.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.32

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

Actual output

^[[I
 ▐▛███▜▌   Claude Code v2.1.31
▝▜█████▛▘  Sonnet 4.5 · Claude Pro
  ▘▘ ▝▝    ~/code

Notes

• Does NOT occur in iTerm2 with same shell configuration
• Does NOT occur with claude --version
• Only happens during interactive session startup
• The issue is cosmetic only (doesn't affect functionality)