[BUG]Japanese IME kanji conversion clicks trigger unintended command execution

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?

Japanese IME input causes unintended command execution when confirming kanji conversion

Environment

• OS: macOS
• VSCode Version: 1.104.2
• Claude Code Extension Version: 2.0.0
• IME: macOS Japanese Input

Description

When typing in Japanese using the macOS Japanese Input (IME), clicking to confirm kanji conversion is mistakenly interpreted as a command execution in Claude Code, causing unintended actions.

Steps to Reproduce

1. Open VSCode with Claude Code extension (v2.0.0) enabled
2. Start typing in Japanese using macOS Japanese Input (e.g., typing "jikkou" じっこう)
3. When the IME shows conversion candidates, click to select and confirm the kanji conversion (実行)
4. The click intended for IME conversion confirmation triggers command execution in Claude Code

Expected Behavior

Clicking during Japanese IME composition should only confirm the kanji conversion and should not trigger any command execution in the Claude Code extension.

Actual Behavior

The click intended for IME conversion confirmation is incorrectly interpreted as a command execution click, causing unintended actions in Claude Code to be executed.

Impact

This makes it extremely difficult for Japanese users to use Claude Code effectively, as any kanji conversion requires clicking, which constantly triggers unintended command executions.

Additional Context

This is a common issue with IME input handling in extensions. The extension should check for IME composition events (compositionstart, compositionupdate, compositionend) to properly distinguish between IME-related clicks and actual user command intentions.

During active IME composition (when isComposing property is true), input events should not be treated as command executions.

What Should Happen?

1. User starts typing in Japanese → compositionstart event fires

• Extension enters "composition mode"
• All click events during this mode should be ignored for command execution

1. User types romaji and converts to kanji → compositionupdate events fire

• IME shows conversion candidates
• User clicks on a candidate to select it
• This click should ONLY affect the IME, not trigger any extension commands

1. User confirms the final conversion → compositionend event fires

• The finalized text (e.g., "実行") is committed to the input field
• Extension exits "composition mode"
• Only after this point should clicks be processed as potential command executions

1. User manually submits the command → User presses Enter or clicks a "Send" button

• This is when the command should actually be executed
• This is a separate, intentional action from IME conversion

Error Messages/Logs

Steps to Reproduce

• The click on the kanji conversion candidate is incorrectly interpreted as a command execution click
• Claude Code immediately executes or attempts to process the incomplete input
• This results in unintended command execution or errors
• The user experience is severely disrupted as every kanji conversion triggers unwanted actions

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.00

Claude Code Version

1.0.100 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_