[BUG] Shift+Enter no longer inserts backslash \ for multiline input in VS Code terminal

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?

Title: Shift+Enter no longer inserts backslash \ for multiline input in VS Code terminal

Description:

Bug Report

Environment:

• Claude Code version: 2.1.71
• VS Code (integrated terminal)
• macOS

Expected Behavior

When pressing Shift+Enter in the Claude Code prompt within VS Code's integrated terminal, a backslash \ should be appended at the end of the current line followed by a newline,
allowing multiline input before submission.

Actual Behavior

Shift+Enter creates a new line but no longer automatically inserts the \ character. The multiline functionality itself still works, but the visual backslash continuation indicator
is missing.

Regression

This worked correctly in earlier versions. The behavior changed approximately around version 2.1.50 (exact version unknown due to frequent updates). No changes were made to VS Code
keybindings or settings.

Steps to Reproduce

1. Open Claude Code in VS Code's integrated terminal
2. Start typing a prompt
3. Press Shift+Enter to create a multiline input
4. Observe: no \ is inserted at the end of the line

Workaround

Manually typing \ before pressing Shift+Enter, which is less convenient than the previous automatic behavior.

What Should Happen?

Pressing Shift+Enter in the Claude Code prompt running through the official "Claude for VS Code" extension (Anthropic's anthropic.claude-code) should automatically insert a
backslash \ at the end of the current line and move the cursor to a new line, preserving the multiline input mode without submitting the prompt. This was the default behavior in
earlier versions (prior to ~2.1.50) and made multiline prompt editing seamless.

Error Messages/Logs

Steps to Reproduce

1. Install the official "Claude for VS Code" extension (anthropic.claude-code) — version 2.1.71
2. Open Claude Code in VS Code's integrated terminal (via the extension)
3. Start typing any prompt text
4. Press Shift+Enter to create a multiline input
5. Observe: a new line is created but no \ character is automatically inserted at the end of the previous line
6. Previously (before ~v2.1.50), Shift+Enter would insert \ + newline automatically

Note: No custom VS Code keybindings for Shift+Enter are configured. The issue persists with default keybinding settings.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.71

Platform

AWS Bedrock

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_