[FEATURE] env var that can resolve to marketplace location

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Right now the CLAUDE_PLUGIN_ROOT resolves to the cached version of a plugin: ~/.claude/plugins/cache/<marketplace>/<plugin_name>/<version>/

this works great but also causes an issue with a marketplace that has shared files and scripts that are reused across plugins. Such as a metrics logging script or json or html template file.

Proposed Solution

I'd like to have an env var: CLAUDE_PLUGIN_MARKETPLACE_DIR that evaluates to the marketplace location:

~/.claude/plugins/marketplaces/<marketplace>

this would allow us to use hooks and scripts from the SKILL.md and point it to a location in the marketplace with the shared code and scripts. 

Alternative Solutions

_No response_

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

This would be used for all marketplace plugins that I am building out.

Additional Context

_No response_