[BUG] Plugin marketplace fails to load - Invalid schema errors

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?

The /plugin command fails to load the marketplace with schema validation errors.

## Claude Code Version
2.1.17

## Platform
macOS (Darwin 25.0.0)

What Should Happen?

The plugin marketplace should load successfully, displaying available plugins and allowing installation of plugins like telegram@claude-plugins-official.

Error Messages/Logs

Failed to load all marketplaces. Errors: claude-plugins-official: Invalid schema: plugins.2.source: Invalid input, plugins.5.source: Invalid input, plugins.12.source:
   Invalid input, plugins.29.source: Invalid input, plugins.49.source: Invalid input, plugins.58.source: Invalid input, plugins.64.source: Invalid input,               
  plugins.66.source: Invalid input, plugins.88.source: Invalid input, plugins.98.source: Invalid input, plugins.106.source: Invalid input, plugins.118.source: Invalid  
  input

Steps to Reproduce

1. Run /plugin or /plugin install telegram@claude-plugins-official
2. Marketplace fails to load

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.17

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_