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Adding Your Marketplace to Codex

This guide walks you through adding your Willow plugin marketplace to OpenAI Codex.

Prerequisites​

Repository structure​

Willow generates the following layout for Codex:

your-org-slug/
├── .agents/
│   └── plugins/
│       └── marketplace.json
├── plugins/
│   └── <plugin-slug>/
│       ├── .codex-plugin/
│       │   └── plugin.json
│       ├── .mcp.json
│       ├── skills/
│       │   └── <skill-slug>/
│       │       └── SKILL.md
│       └── agents/
│           └── <agent-slug>.md

Key differences from other platforms:

  • The root marketplace manifest lives at .agents/plugins/marketplace.json
  • Each plugin has its plugin.json inside a .codex-plugin/ folder
  • Each plugin entry in the marketplace includes a policy object controlling installation behavior

Step 1: Marketplace file​

The marketplace file at .agents/plugins/marketplace.json is generated automatically by Willow. It looks like this:

{
  "name": "my-marketplace",
  "interface": {
    "displayName": "My Marketplace"
  },
  "plugins": [
    {
      "name": "my-plugin",
      "source": {
        "source": "local",
        "path": "./plugins/my-plugin"
      },
      "policy": {
        "installation": "AVAILABLE",
        "authentication": "ON_INSTALL"
      },
      "category": "Productivity"
    }
  ]
}

Step 2: Deploy as a repo marketplace​

The .agents/plugins/marketplace.json file should be at the repository root level:

# Your repo should contain:
# .agents/plugins/marketplace.json
# plugins/<plugin-slug>/...

Step 3: Restart Codex​

After adding or updating the marketplace file, restart Codex so it picks up the new configuration.

Step 4: Browse and install plugins​

Open the plugin directory in Codex, choose your marketplace, and browse or install the plugins in your curated list.

Updating the marketplace​

After Willow syncs changes to your repository, restart Codex so the local install picks up the new files.

Personal marketplace​

For a personal (non-repo) marketplace, use ~/.agents/plugins/marketplace.json and store plugins under ~/.codex/plugins/.

Further reading​

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