Plugin marketplace fails to load: git-subdir source type not supported in schema validator

Bug Description

/plugin command fails with schema validation error, preventing the entire marketplace from loading.

Error Message

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 /Users/.../.claude/plugins/marketplaces/anthropics-claude-plugins-official/.claude-plugin/marketplace.json: Invalid schema: plugins.56.source: Invalid input

Root Cause

Plugin #56 (semgrep) in the official marketplace uses a git-subdir source type:

{
  "name": "semgrep",
  "source": {
    "source": "git-subdir",
    "url": "https://github.com/semgrep/mcp-marketplace.git",
    "path": "plugin"
  }
}

The CLI schema validator does not recognize git-subdir as a valid source type. Since marketplace parsing is all-or-nothing, this single invalid entry blocks the entire plugin marketplace from loading.

Environment

• Claude Code version: 2.1.63
• OS: macOS (Darwin 25.1.0)

Steps to Reproduce

1. Run /plugin in Claude Code
2. Marketplace fails to load with the above error

Attempted Fixes

• claude update (still on 2.1.63, issue persists)
• Clearing marketplace cache (rm -rf ~/.claude/plugins/marketplaces/) — re-fetches the same broken file

Suggested Fix

Either:

1. Add git-subdir to the allowed source types in the schema validator
2. Make marketplace loading resilient — skip individual plugins with unrecognized source types instead of failing the entire marketplace