[BUG] pluginRoot in marketplace is not respected when installing plugin

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?

When using a marketplace that declares a metadata.pluginRoot path (for instance to ./plugins), installing any of the detected plugins then fails with an error "file not found" with the path .claude/plugins/marketplaces/xxx-marketplace/a-plugin/....

It skips the pluginRoot as the path should be .claude/plugins/marketplaces/xxx-marketplace/plugins/a-plugin/....

- .claude/plugins/marketplaces/xxx-marketplace/a-plugin/...
+ .claude/plugins/marketplaces/xxx-marketplace/plugins/a-plugin/...

What Should Happen?

Plugin installation should work.

Error Messages/Logs

Steps to Reproduce

Apologies, I'm filling this in a rush. I'll provide a reproduction scenario later if needed.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.140

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

_No response_