`/plugin marketplace add` fails with schema validation error for `git-subdir` source type

Bug Report

Description

Running /plugin marketplace add anthropics/claude-plugins-official fails with a schema validation error because the marketplace file contains a plugin with a git-subdir source type that Claude Code v2.1.58 does not recognize.

Steps to Reproduce

/plugin marketplace add anthropics/claude-plugins-official

Error

Error: Failed to parse marketplace file at /Users/wei.feng/.claude/plugins/marketplaces/anthropics-claude-plugins-official/.claude-plugin/marketplace.json: Invalid schema: /Users/wei.feng/.claude/plugins/marketplaces/anthropics-claude-plugins-official/.claude-plugin/marketplace.json plugins.56.source: Invalid input

Root Cause

Plugin index 56 (semgrep) in the latest anthropics/claude-plugins-official marketplace uses a new git-subdir source type:

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

Claude Code v2.1.58 supports "source": "url" but does not recognize "source": "git-subdir", causing the Zod schema validation to fail on the entire marketplace file. This prevents the marketplace from being added at all.

Environment

• Claude Code version: 2.1.58
• OS: macOS (Darwin 25.3.0)

Expected Behavior

Either:

1. Claude Code should support the git-subdir source type, or
2. The CLI should skip/warn on unknown plugin entries rather than rejecting the entire marketplace file