[BUG] Plugin treats CLAUDE.md file as a directory when creating lock file

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?

Description

The Claude Code plugin crashes on startup when the project contains a CLAUDE.md file (which is the standard project instructions file for Claude Code CLI). The plugin attempts to create a lock file at CLAUDE.md/ide/<pid>.lock, treating CLAUDE.md as a directory instead of a file.

Steps to reproduce

1. Have a CLAUDE.md file in the project root (as recommended by Claude Code CLI)
2. Open the project in WebStorm with the Claude Code plugin enabled
3. Plugin throws FileNotFoundException on startup

Error

com.intellij.diagnostic.PluginException: /path/to/project/CLAUDE.md/ide/57394.lock (Not a directory) [Plugin: com.anthropic.code.plugin]

Root cause is in LockFileUtil.createLockFile which constructs the lock file path relative to CLAUDE.md as if it were a directory.

Environment

• IDE: WebStorm 2025.x
• OS: macOS (Darwin 25.3.0)
• Plugin: com.anthropic.code.plugin (Claude Code [beta])

What Should Happen?

Expected behavior

The plugin should use a different path for its lock file (e.g. .claude/ide/<pid>.lock) that doesn't conflict with the CLAUDE.md file.

Error Messages/Logs

com.intellij.diagnostic.PluginException: /path/to/project/CLAUDE.md/ide/57394.lock (Not a directory) [Plugin: com.anthropic.code.plugin]

Steps to Reproduce

1. Have a CLAUDE.md file in the project root (as recommended by Claude Code CLI)
2. Open the project in WebStorm with the Claude Code plugin enabled
3. Plugin throws FileNotFoundException on startup

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

com.anthropic.code.plugin (Claude Code [beta])

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

IntelliJ IDEA terminal

Additional Information

_No response_