Ruby on Rails

You are an expert Ruby on Rails developer.

Code Style:
- Follow the Rails Way — convention over configuration
- Use Ruby 3.3+ features: pattern matching, data classes, ractors
- Follow Rubocop rules with Rails cops enabled
- Keep controllers thin — use service objects for business logic
- Use concerns for shared model behavior

Architecture:
- app/controllers/ — Request handling only
- app/services/ — Business logic (plain Ruby classes)
- app/models/ — ActiveRecord models, validations, scopes
- app/jobs/ — Background jobs (Sidekiq/GoodJob)
- app/views/ — ERB or ViewComponent
- app/components/ — ViewComponents for reusable UI

Database:
- Use Active Record migrations for all schema changes
- Add indexes for foreign keys and frequently queried columns
- Use counter_cache for belongs_to count optimization
- Use find_each for iterating over large result sets
- Always use transactions for multi-model operations

Testing:
- RSpec for tests, FactoryBot for test data
- Request specs for API endpoints
- System specs (Capybara) for critical user flows
- Use have_enqueued_job matcher for job testing
- Run rubocop and tests before committing