[BUG] /plugin install fails on Windows - missing backslash causes path to resolve .claude as part of username

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?

Path is resolved as C:\Users\<username>.claude\plugins\marketplaces\... (missing backslash before .claude), so the directory does not exist and marketplace loading fails.

Likely cause: Path construction on Windows is missing the backslash separator between the username and .claude, resulting in userx.claude being treated as a single directory name rather than userx\.claude

What Should Happen?

Plugin marketplace is loaded from C:\Users\<username>\.claude\plugins\marketplaces\...

Error Messages/Logs

Failed to load all marketplaces. Errors: claude-plugins-official: Failed to load
     marketplace "claude-plugins-official" from source (github): Failed to parse
     marketplace file at C:\Users\userx.claude\plugins\marketplaces\anthropics-claude-pl
     ugins-official.claude-plugin\marketplace.json: Invalid schema:
     C:\Users\userx.claude\plugins\marketplaces\anthropics-claude-plugins-official.claud
     e-plugin\marketplace.json plugins.0.source: Invalid input, plugins.1.source: Invalid
      input, plugins.6.source: Invalid input, plugins.7.source: Invalid input,
     plugins.10.source: Invalid input, plugins.11.source: Invalid input,
     plugins.20.source: Invalid input, plugins.21.source: Invalid input,
     plugins.22.source: Invalid input, plugins.23.source: Invalid input,
     plugins.24.source: Invalid input, plugins.25.source: Invalid input,
     plugins.26.source: Invalid input, plugins.27.source: Invalid input,
     plugins.31.source: Invalid input, plugins.36.source: Invalid input,
     plugins.37.source: Invalid input, plugins.38.source: Invalid input,
     plugins.41.source: Invalid input, plugins.61: Unrecognized key: "displayName",
     plugins.69.source: Invalid input, plugins.74.source: Invalid input,
     plugins.75.source: Invalid input, plugins.76.source: Invalid input,
     plugins.83.source: Invalid input, plugins.112.source: Invalid input,
     plugins.114.source: Invalid input, plugins.115.source: Invalid input,
     plugins.116.source: Invalid input, plugins.124.source: Invalid input,
     plugins.127.source: Invalid input, plugins.129.source: Invalid input,
     plugins.131.source: Invalid input, plugins.133.source: Invalid input,
     plugins.135.source: Invalid input, plugins.139.source: Invalid input,
     plugins.140.source: Invalid input, plugins.142.source: Invalid input,
     plugins.156.source: Invalid input, plugins.162.source: Invalid input,
     plugins.165.source: Invalid input, plugins.173.source: Invalid input,
     plugins.176.source: Invalid input, plugins.178.source: Invalid input,
     plugins.180.source: Invalid input, plugins.182.source: Invalid input,
     plugins.184.source: Invalid input, plugins.190.source: Invalid input,
     plugins.196.source: Invalid input, plugins.207.source: Invalid input,
     plugins.208.source: Invalid input, plugins.209.source: Invalid input,
     plugins.217.source: Invalid input, plugins.219.source: Invalid input

Steps to Reproduce

1. Run /plugin install superpowers@claude-plugins-official on Windows

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.177

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_