[BUG] /plugin slash commands show skill as installed but skill cannot be invoked

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?

Using /plugin marketplace add and /plugin install inside a Claude Code session reports success and the skill appears as installed in settings, but attempting to invoke the skill returns "skill not found".

What Should Happen?

Skills installed via the /plugin slash commands should be invokable in the same way as skills installed via the claude plugin CLI commands.

Steps to Reproduce

1. In a Claude Code session, run /plugin marketplace add FrankLedo/claude-skills
2. Run /plugin install slack-monitor
3. Observe success message and skill appearing in settings
4. Attempt to invoke the skill with /slack-monitor
5. Observe "skill not found" error

Workaround: Installing via the CLI works correctly:

claude plugin marketplace add FrankLedo/claude-skills
claude plugin install slack-monitor

Error Messages/Logs

skill not found

Claude Code Version

_Latest_

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

zsh

Additional Information

_No response_