[Bug] Keyboard Input Handling Breaks Option Key Combinations in IntelliJ Terminal on macOS

Bug Description

Subject: Claude Code: Option key combinations produce wrong characters in IntelliJ IDEA terminal on macOS with Czech keyboard
Environment:

Claude Code version: 2.0.11
Operating System: macOS (Apple Silicon/Intel)
Keyboard Layout: Czech - QWERTY
Terminal: IntelliJ IDEA 2025.2.3 Ultimate Edition (JetBrains-JediTerm)
Shell: zsh
Locale: en_US.UTF-8 (explicitly set via LANG and LC_ALL environment variables)

Description:
When running Claude Code in IntelliJ IDEA's integrated terminal with a Czech keyboard layout, Option key combinations produce incorrect characters. Specifically:

Option+2 produces ě instead of @
Option+3 produces š instead of #
Option+4 produces č instead of $

This happens even when locale is explicitly set to en_US.UTF-8:
bashTERM=xterm-256color LANG=en_US.UTF-8 LC_ALL=en_US.UTF-8 LC_CTYPE=en_US.UTF-8 claude
Expected behavior:
Option key combinations should produce the correct special characters (@, #, $, etc.) as they do in other terminal applications.
Actual behavior:
Option key combinations produce Czech-specific characters (ě, š, č, etc.) that correspond to the Czech keyboard layout with cs_CZ.UTF-8 locale.
Works correctly in:

iTerm2
macOS Terminal.app
Regular zsh shell in IntelliJ terminal (when Claude Code is NOT running)

Does NOT work in:

IntelliJ IDEA terminal when Claude Code is running

Steps to reproduce:

Set up macOS with Czech keyboard layout
Open IntelliJ IDEA 2025.2.3
Open integrated terminal
Set locale: export LANG=en_US.UTF-8 LC_ALL=en_US.UTF-8
Start Claude Code: claude
Try to type @ using Option+2
Character ě appears instead of @

Additional notes:
When Claude Code is paused (Ctrl+Z) and control returns to the shell prompt, Option+2 produces <ffffff> (suggesting a different input handling issue in the IntelliJ terminal itself). However, when Claude Code is active, it consistently produces Czech characters regardless of locale settings.
This appears to be an issue with how Claude Code handles keyboard input from the JetBrains terminal emulator, possibly not respecting the locale environment variables or the terminal's input method.
Workaround:
Currently using iTerm2 or Terminal.app for Claude Code as a temporary solution.

Environment Info

• Platform: darwin
• Terminal: intellij
• Version: 2.0.11
• Feedback ID: b9b39d16-2f7c-436d-ab99-98793a6c7053

Errors

[{"error":"Error: Plugin source missing\n    at NSZ (/$bunfs/root/claude:844:36952)\n    at NSZ (/$bunfs/root/claude:844:37639)\n    at F0Y (/$bunfs/root/claude:845:4190)\n    at F0Y (/$bunfs/root/claude:845:4255)\n    at z0Y (/$bunfs/root/claude:845:1660)\n    at z0Y (/$bunfs/root/claude:845:1967)\n    at <anonymous> (/$bunfs/root/claude:846:3097)\n    at <anonymous> (/$bunfs/root/claude:846:3292)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-10-09T15:24:35.164Z"}]