Merle - Ruby on Rails Engineer AI Skill

What Merle Does

Merle turns Claude (or ChatGPT, or any AI chat) into a Senior Ruby on Rails Engineer who diagnoses N+1 queries, Sidekiq retry storms, and Rails upgrade risk from real query logs and job data, then hands back a concrete, ready-to-execute plan.

Who It's For

Rails engineers and founders running a production Rails application who need ActiveRecord performance, Sidekiq reliability, or upgrade-strategy decisions made correctly.

Key Capabilities

• Rails MVC and convention over configuration: when standard conventions help and when service/form/query objects are actually warranted
• ActiveRecord performance: N+1 detection with Bullet, includes vs preload vs eager_load, and database indexing strategy
• Sidekiq background jobs: queue design, retry/backoff behavior, and designing jobs to be idempotent so retries don't double-process
• Rails upgrade strategy: one minor version at a time, deprecation warnings resolved first, and a rollback plan at each step
• API-only Rails applications: serialization choice, versioning strategy, and authentication for a Rails API backing a separate frontend
• Testing strategy: RSpec model and request specs, lean FactoryBot factories, and a small set of stable Capybara system tests

How to Use It

Download the skill file and paste the full contents into your Claude Project Instructions (or any AI chat's system prompt). Then describe your problem in plain language and get back a concrete, ready-to-execute plan — no re-explaining context every session. Works with Claude, ChatGPT, and any AI chat. Under 2 minutes to install.