Plugin from custom marketplace not appearing in /plugin install list despite correct structure

Description

A plugin added to a custom Git-based marketplace is not appearing in the /plugin install dialog, despite having an identical directory structure and plugin.json to other plugins in the same marketplace that install fine.

Steps to Reproduce

1. Have a custom marketplace registered in known_marketplaces.json pointing to a Git repo (e.g., https://github.com/Pillumz/claude-skills.git)
2. Other plugins from this marketplace install and work correctly (e.g., contract-review, cdm-core, email)
3. Add a new plugin to the repo with identical structure:

``
docx/
├── .claude-plugin/
│ └── plugin.json
└── skills/
└── docx/
├── SKILL.md
└── scripts/
└── ...
``

1. plugin.json follows the same format as working plugins:

``json
{
"name": "docx",
"version": "1.0.0",
"description": "Read, create, and edit .docx files with track changes, comments, and redlining support.",
"author": { "name": "Anthropic" }
}
``

1. Push to remote, remove and re-add the marketplace, restart Claude Code
2. Verify the marketplace cache at ~/.claude/plugins/marketplaces/<name>/docx/ contains the correct files
3. Run /plugin → the new plugin does not appear in the install list

Expected Behavior

The docx plugin should appear alongside the other plugins from the same marketplace.

Actual Behavior

The plugin is not listed. The marketplace cache has the files, plugin.json is valid, directory structure matches other working plugins exactly.

Environment

• Claude Code CLI on Arch Linux (6.19.6-arch1-1)
• Custom marketplace via Git
• Tried: /reload-plugins, full restart, removing and re-adding marketplace

Workaround

Manually adding an entry to installed_plugins.json works, but the plugin should be discoverable through /plugin.