plugin-creator

Plugin Creator

Quick Start

1. Run the scaffold script:

  # Plugin names are normalized to lower-case hyphen-case and must be <= 64 chars.
  # The generated folder and plugin.json name are always the same.
# Run from repo root (or replace .agents/... with the absolute path to this SKILL).
# By default creates in ~/plugins/<plugin-name>.
python3 .agents/skills/plugin-creator/scripts/create_basic_plugin.py <plugin-name>

2. Open <plugin-path>/.codex-plugin/plugin.json and replace [TODO: ...] placeholders.

3. Generate or update the personal marketplace entry when the plugin should appear in Codex UI ordering:

# Personal marketplace entries default to ~/.agents/plugins/marketplace.json.
python3 .agents/skills/plugin-creator/scripts/create_basic_plugin.py my-plugin

If the current Git repo already has .agents/plugins/marketplace.json and the user has not said whether the plugin is personal or shared with their team, ask before generating a marketplace entry. When they choose the repo marketplace, use:

4. Generate/adjust optional companion folders as needed:

<parent-plugin-directory> is the directory where the plugin folder <plugin-name> will be created (for example ~/code/plugins).

What this skill creates

• Default marketplace-backed scaffolds are personal: ~/plugins/<plugin-name>/ plus ~/.agents/plugins/marketplace.json.
• If the current Git repo already has .agents/plugins/marketplace.json and the user has not said personal vs team, ask which marketplace to update before generating a marketplace entry.
• Creates plugin root at /<parent-plugin-directory>/<plugin-name>/.
• Always creates /<parent-plugin-directory>/<plugin-name>/.codex-plugin/plugin.json.
• Fills the manifest with the full schema shape, placeholder values, and the complete interface section.
• Creates or updates the selected marketplace when --with-marketplace is set.
  • If the marketplace file does not exist yet, seed top-level name plus interface.displayName placeholders before adding the first plugin entry.
• <plugin-name> is normalized using skill-creator naming rules:
  • My Plugin → my-plugin
  • My--Plugin → my-plugin
  • underscores, spaces, and punctuation are converted to -
  • result is lower-case hyphen-delimited with consecutive hyphens collapsed
• Supports optional creation of:
  • skills/
  • hooks/
  • scripts/
  • assets/
  • .mcp.json
  • .app.json

Marketplace workflow

• Personal plugins use ~/.agents/plugins/marketplace.json.
• Repo/team plugins use <repo-root>/.agents/plugins/marketplace.json.
• Marketplace root metadata supports top-level name plus optional interface.displayName.
• Treat plugin order in plugins[] as render order in Codex. Append new entries unless a user explicitly asks to reorder the list.
• displayName belongs inside the marketplace interface object, not individual plugins[] entries.
• Each generated marketplace entry must include all of:
  • policy.installation
  • policy.authentication
  • category
• Default new entries to:
  • policy.installation: "AVAILABLE"
  • policy.authentication: "ON_INSTALL"
• Override defaults only when the user explicitly specifies another allowed value.
• Allowed policy.installation values:
  • NOT_AVAILABLE
  • AVAILABLE
  • INSTALLED_BY_DEFAULT
• Allowed policy.authentication values:
  • ON_INSTALL
  • ON_USE
• Treat policy.products as an override. Omit it unless the user explicitly requests product gating.
• The generated plugin entry shape is:

• Use --force only when intentionally replacing an existing marketplace entry for the same plugin name.

• If the selected marketplace file does not exist yet, create it with top-level "name", an "interface" object containing "displayName", and a plugins array, then add the new entry.

• For a brand-new marketplace file, the root object should look like:

Required behavior

• Outer folder name and plugin.json "name" are always the same normalized plugin name.
• Do not remove required structure; keep .codex-plugin/plugin.json present.
• Keep manifest values as placeholders until a human or follow-up step explicitly fills them.
• If creating files inside an existing plugin path, use --force only when overwrite is intentional.
• Preserve any existing marketplace interface.displayName.
• When generating marketplace entries, always write policy.installation, policy.authentication, and category even if their values are defaults.
• Add policy.products only when the user explicitly asks for that override.
• Keep marketplace source.path relative to the selected marketplace root as ./plugins/<plugin-name>.
• When the workflow created or updated a marketplace-backed plugin, end the final user-facing response with a short Codex app handoff. Say To view this in the Codex app: and write View <normalized plugin name> and Share <normalized plugin name> as Markdown links, not raw URLs or code spans.
• The View deeplink uses codex://plugins/<normalized plugin name>?marketplacePath=<absolute marketplace.json path>. The Share deeplink uses the same URL with &mode=share.
• Replace the placeholders with the real normalized plugin name and absolute marketplace.json path from the scaffolded plugin. URL-encode the path segment and query value when needed.
• Do not add pluginName or hostId query parameters to these deeplinks. Codex derives both after the user clicks the link.
• Do not emit the View <normalized plugin name> or Share <normalized plugin name> links when no marketplace entry was created or updated.

Reference to exact spec sample

For the exact canonical sample JSON for both plugin manifests and marketplace entries, use:

• references/plugin-json-spec.md

Validation

After editing SKILL.md, run: