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mylesmcook/mcook-plugin-builder

v0.2.4MIT

Build portable Agent Plugins and OpenAI-compatible plugins for Myles Codex Plugins.

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Myles Plugin Builder

Build portable Agent Plugins and OpenAI-compatible plugins for this marketplace.

Included skill

  • build-mcook-plugin selects the portable, OpenAI-native, or dual package contract; keeps MCP packaging separate from MCP wire-protocol compatibility; registers the package in .agents/plugins/marketplace.json; and runs target-specific validation.

The skill uses the local repository layout: plugin folders live at the repository root and marketplace entries use relative paths such as ./plugin-name.

Use in Codex

$mcook-plugin-builder:build-mcook-plugin Create a marketplace-ready Codex plugin for this workflow.

Portable packages follow Agent Plugins 1.0.0, including root plugin.json, fixed component discovery, root mcp.json, and canonical schemas. The builder includes an uv-native validator for schema, path, transport, secret, overlay, and marketplace checks.

OpenAI-native and compatibility layers continue to follow OpenAI's current plugin packaging documentation. They remain a separate contract from the portable core.

Every release must pass the skill's Agent Plugins conformance gate or carry an explicit, evidence-backed native-only exception in its README. Native-only packages must state their compatibility limits and pass the applicable native checks; they cannot claim Agent Plugins conformance.

The portable validator accepts both repository package roots and Codex's versioned installed-cache layout, so the same package checks can prove source and installed bytes without renaming the cache.

MCP 2026-07-28 is also separate. The skill documents Codex's opt-in mode and requires modern discovery, stateless metadata, pagination, cache fields, multi-round input, and transport-specific tests before claiming support. See the MCP key changes.

It targets the private mcook-plugins-local marketplace. Public publication to the shared ChatGPT/Codex Plugins Directory remains a separate submission and review workflow.

License

MIT. See LICENSE.

Marketplace source validation

The Codex catalog contains cici@mcook-plugins-local, the repository-owned replacement for Claude Code Advisor. See Cici for the three direct CLI skills and migration order.

External metadata uses the documented Codex git-subdir (or repository-root url) contract, credential-free GitHub HTTPS and exactly one full commit ref or sha. Local entries remain inside the marketplace root. The builder’s metadata-only mode does not establish package validity, remote availability, license compatibility, or installed-byte identity:

uv run mcook-plugin-builder/skills/build-mcook-plugin/scripts/validate_agent_plugin.py --marketplace-entry cici --marketplace .agents/plugins/marketplace.json --marketplace-root .

Separately inspect the pinned package and validate an isolated installation. Keep external native packages in their original format; the portable validator is not an OpenAI-native validator. See Codex marketplace source documentation.