Shift+Enter no longer inserts newline in prompt (sends message instead)

Description

Shift+Enter no longer works to insert a newline in the input prompt. Instead of creating a new line, it sends the message immediately — same behavior as Enter alone.

This makes it impossible to compose multi-line prompts without copy-pasting.

Environment

• OS: WSL2 (Linux 6.6.87.2-microsoft-standard-WSL2)
• Shell: bash
• Terminal: Windows Terminal
• Claude Code version: latest (as of 2026-03-07)

Expected behavior

Shift+Enter should insert a newline character in the prompt input, allowing multi-line composition before sending.

Actual behavior

Shift+Enter sends the message immediately, identical to pressing Enter.

Workaround

None practical — users must paste multi-line text or use \ continuation.