Write Ruby gems following Andrew Kane's proven patterns and philosophy. Use when creating new Ruby gems, refactoring existing gems, designing gem APIs, or when the user wants clean, minimal, production-ready Ruby library code. Triggers on requests like "create a gem", "write a Ruby library", "design a gem API", or mentions of Andrew Kane's style.
npx skills add https://github.com/Microck/ordinary-claude-skills --skill andrew-kane-gem-writer
Write Ruby gems following Andrew Kane's battle-tested patterns from 100+ gems with 374M+ downloads (Searchkick, PgHero, Chartkick, Strong Migrations, Lockbox, Ahoy, Blazer, Groupdate, Neighbor, Blind Index).
Simplicity over cleverness. Zero or minimal dependencies. Explicit code over metaprogramming. Rails integration without Rails coupling. Every pattern serves production use cases.
Every gem follows this exact pattern in lib/gemname.rb:
# 1. Dependencies (stdlib preferred)
require "forwardable"
# 2. Internal modules
require_relative "gemname/model"
require_relative "gemname/version"
# 3. Conditional Rails (CRITICAL - never require Rails directly)
require_relative "gemname/railtie" if defined?(Rails)
# 4. Module with config and errors
module GemName
class Error < StandardError; end
class InvalidConfigError < Error; end
class << self
attr_accessor :timeout, :logger
attr_writer :client
end
self.timeout = 10 # Defaults set immediately
end
The signature Kane pattern—single method call configures everything:
# Usage
class Product < ApplicationRecord
searchkick word_start: [:name]
end
# Implementation
module GemName
module Model
def gemname(**options)
unknown = options.keys - KNOWN_KEYWORDS
raise ArgumentError, "unknown keywords: #{unknown.join(", ")}" if unknown.any?
mod = Module.new
mod.module_eval do
define_method :some_method do
# implementation
end unless method_defined?(:some_method)
end
include mod
class_eval do
cattr_reader :gemname_options, instance_reader: false
class_variable_set :@@gemname_options, options.dup
end
end
end
end
Always use ActiveSupport.on_load—never require Rails gems directly:
# WRONG
require "active_record"
ActiveRecord::Base.include(MyGem::Model)
# CORRECT
ActiveSupport.on_load(:active_record) do
extend GemName::Model
end
# Use prepend for behavior modification
ActiveSupport.on_load(:active_record) do
ActiveRecord::Migration.prepend(GemName::Migration)
end
Use class << self with attr_accessor, not Configuration objects:
module GemName
class << self
attr_accessor :timeout, :logger
attr_writer :master_key
end
def self.master_key
@master_key ||= ENV["GEMNAME_MASTER_KEY"]
end
self.timeout = 10
self.logger = nil
end
Simple hierarchy with informative messages:
module GemName
class Error < StandardError; end
class ConfigError < Error; end
class ValidationError < Error; end
end
# Validate early with ArgumentError
def initialize(key:)
raise ArgumentError, "Key must be 32 bytes" unless key&.bytesize == 32
end
# test/test_helper.rb
require "bundler/setup"
Bundler.require(:default)
require "minitest/autorun"
require "minitest/pride"
# test/model_test.rb
class ModelTest < Minitest::Test
def test_basic_functionality
assert_equal expected, actual
end
end
Zero runtime dependencies when possible:
Gem::Specification.new do |spec|
spec.name = "gemname"
spec.version = GemName::VERSION
spec.required_ruby_version = ">= 3.1"
spec.files = Dir["*.{md,txt}", "{lib}/**/*"]
spec.require_path = "lib"
# NO add_dependency lines - dev deps go in Gemfile
end
method_missing (use define_method instead)@@class_variables (use class << self)For deeper patterns, see:
Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP) or Node/TypeScript (MCP SDK).
Automatically creates user-facing changelogs from git commits by analyzing commit history, categorizing changes, and transforming technical commits into clear, customer-friendly release notes. Turns hours of manual changelog writing into minutes of automated generation.
Use when implementation is complete, all tests pass, and you need to decide how to integrate the work - guides completion of development work by presenting structured options for merge, PR, or cleanup
Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP) or Node/TypeScript (MCP SDK).
React Native and Expo best practices for building performant mobile apps. Use when building React Native components, optimizing list performance, implementing animations, or working with native modules. Triggers on tasks involving React Native, Expo, mobile performance, or native platform APIs.
React and Next.js performance optimization guidelines from Vercel Engineering. This skill should be used when writing, reviewing, or refactoring React/Next.js code to ensure optimal performance patterns. Triggers on tasks involving React components, Next.js pages, data fetching, bundle optimization, or performance improvements.
Next.js best practices - file conventions, RSC boundaries, data patterns, async APIs, metadata, error handling, route handlers, image/font optimization, bundling
Use when starting feature work that needs isolation from current workspace or before executing implementation plans - creates isolated git worktrees with smart directory selection and safety verification
Take microck/andrew-kane-gem-writer from the repository into ~/.claude/skills for personal
use, or into .claude/skills inside a project.
The agent identifies a skill by the name field in its header. Two skills with the
same name cannot sit side by side — one of them will be ignored.