Plugin marketplace add fails with schema validation errors for git-subdir source type

Description

Running /plugin marketplace add anthropics/claude-plugins-official fails with schema validation errors for multiple plugins.

Error Message

Error: 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.63.source: Invalid input, plugins.65.source: Invalid input, plugins.87.source: Invalid input, plugins.97.source: Invalid input, plugins.105.source: Invalid input, plugins.117.source: Invalid input

Root Cause

The official marketplace (anthropics/claude-plugins-official) contains plugins with source types that the current Claude Code schema validator doesn't recognize:

• "source": "git-subdir" - Used by plugins like ai-firstify, amazon-location-service, aws-serverless, deploy-on-aws, helius, legalzoom, migration-to-aws, neon, railway, semgrep, stripe, zapier
• "source": "github" - Used by stagehand

Example from ai-firstify (index 2):

"source": {
  "source": "git-subdir",
  "url": "techwolf-ai/ai-first-toolkit",
  "path": "plugins/ai-firstify",
  "ref": "main",
  "sha": "7f18e11d694b9ae62ea3009fbbc175f08ae913df"
}

Expected Behavior

The marketplace should be added successfully, or unsupported source types should be gracefully skipped with a warning rather than failing the entire operation.

Environment

• Claude Code version: 2.1.85
• Platform: macOS (Darwin 25.3.0)

Suggested Fix

Either:

1. Add support for git-subdir and github source types to the schema validator
2. Make the marketplace addition more resilient by skipping invalid plugins with warnings instead of failing entirely