/doctor false positive: Plugin validation uses incorrect marketplace identifier format

Bug Description

The /doctor command incorrectly validates plugin marketplace references by constructing marketplace identifiers that don't match the actual marketplace names defined in marketplace.json.

Steps to Reproduce

1. Add a GitHub-hosted marketplace with a name different from the org name:

``bash
# Marketplace repo: DiligentCorp/platform-sre-standards
# Marketplace name in .claude-plugin/marketplace.json: "platform-sre-standards"
``

1. Install a plugin from this marketplace:

``bash
# Plugin installed as: psre-workflow@platform-sre-standards
``

1. Enable the plugin in ~/.claude/settings.json:

``json
"enabledPlugins": {
"psre-workflow@platform-sre-standards": true
}
``

1. Run /doctor

Expected Behavior

/doctor should recognize the plugin as valid since:

• The marketplace is properly registered in ~/.claude/plugins/known_marketplaces.json as platform-sre-standards
• The plugin is properly installed in ~/.claude/plugins/installed_plugins.json as psre-workflow@platform-sre-standards
• The plugin is functional (all skills load correctly)

Actual Behavior

/doctor reports:

- Plugin (psre-workflow@DiligentCorp-platform-sre-standards): Plugin psre-workflow not found in marketplace DiligentCorp-platform-sre-standards

Root Cause

/doctor appears to be constructing the marketplace identifier as {GitHubOrg}-{MarketplaceName} (e.g., DiligentCorp-platform-sre-standards) instead of using the actual marketplace name from the marketplace.json file (e.g., platform-sre-standards).

Environment

• OS: macOS (Darwin 24.6.0)
• Claude Code: Desktop/CLI
• Model: Opus 4.7
• Plugin repo: https://github.com/DiligentCorp/platform-sre-standards

Supporting Files

~/.claude/plugins/known_marketplaces.json

{
  "platform-sre-standards": {
    "source": {
      "source": "github",
      "repo": "DiligentCorp/platform-sre-standards"
    },
    "installLocation": "/Users/mmoore/.claude/plugins/marketplaces/platform-sre-standards",
    "lastUpdated": "2026-05-14T15:52:57.779Z",
    "autoUpdate": true
  }
}

marketplace.json from the plugin repo

{
  "name": "platform-sre-standards",
  "owner": {
    "name": "Platform SRE"
  },
  "plugins": [
    {
      "name": "psre-workflow",
      "source": "./plugins/psre-workflow",
      "description": "Enforcing platform sre standards and providing a generalized AI workflow",
      "version": "1.4.1"
    }
  ]
}

~/.claude/plugins/installed_plugins.json (excerpt)

{
  "psre-workflow@platform-sre-standards": [
    {
      "scope": "user",
      "installPath": "/Users/mmoore/.claude/plugins/cache/platform-sre-standards/psre-workflow/1.4.1",
      "version": "1.4.1",
      "installedAt": "2026-05-06T22:53:14.782Z",
      "lastUpdated": "2026-05-13T17:50:24.835Z",
      "gitCommitSha": "7bc4bfbf741344854942db9b035e3a8cfe5bb7d9"
    }
  ]
}

Suggested Fix

/doctor should use the marketplace name as registered in known_marketplaces.json (the key in the JSON object) rather than attempting to derive it from the GitHub repo path.

Impact

• Users receive false positive warnings that their properly configured plugins are broken
• May cause confusion about whether plugins are properly installed
• Low severity (does not affect plugin functionality)