Rails Patterns

Framework patterns for modern Ruby on Rails applications (Rails 7.1+ and 8.x). Rails is opinionated by design; these are the patterns the community has converged on for apps that stay maintainable past the 50-model mark. This skill is the "how." For the "what" and "when" (the decisions about which pattern to reach for), see the Ruby patterns rules — rules/ruby/patterns.md in this repository, installed as rules/ecc/ruby/patterns.md.

When to Activate

• Building a Rails application (full-stack, API-only, or hybrid)
• Reviewing a PR that touches app/ or config/
• Generating models, controllers, services, or jobs
• A controller action grows past ~10 lines
• A model file grows past ~200 lines
• ActiveRecord queries start appearing in controllers or views

Core Concepts

The directory contract

Rails apps follow a predictable structure. Add directories deliberately, not casually.

app/
  models/         ActiveRecord models. Persistence and domain logic close to the data.
  controllers/    HTTP request handling. Thin orchestration only.
  views/          ERB templates. No business logic.
  components/     ViewComponent classes. View logic that need…