[BUG] Stop hook fails with EEXIST when plugin data directory already exists

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?

Stop hooks from plugins fail with EEXIST: file already exists, mkdir when the plugin data directory already exists. The error occurs on every stop hook invocation after the first run.

This is the same root cause as several other EEXIST bugs (#33118, #36919, #37306) — all are missing { recursive: true } on mkdir calls. Closing #39108 as a duplicate in favor of this report.

What Should Happen?

The plugin data directory creation should use recursive/idempotent mkdir (fs.mkdir with { recursive: true }) so it doesn't fail if the directory already exists.

Error Messages/Logs

Ran 1 stop hook (ctrl+o to expand)
  ⎿  Stop hook error: Failed to run: EEXIST: file already exists, mkdir
     'C:\Users\PC\.claude\plugins\data\qingyi-qingyi'

The directory already exists from a previous session:

$ ls ~/.claude/plugins/data/
qingyi-qingyi/
superpowers-claude-plugins-official/

Steps to Reproduce

1. Install a plugin that uses a stop hook
2. Run a Claude Code session — stop hook works on first run (creates data dir)
3. Run another session — stop hook fails because directory already exists

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.79

Claude Code Version

2.1.85

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

IntelliJ IDEA terminal

Additional Information

The hook itself never executes — the error is in the plugin infrastructure before the hook runs. The fix should be a one-line change: use fs.mkdir(path, { recursive: true }) instead of fs.mkdir(path) when creating the plugin data directory.