ruby-conventions

Write idiomatic Ruby (and Rails)

Ruby's expressiveness helps readers when objects are small, named well and follow the idioms the repo already uses; it hurts when metaprogramming hides behaviour or Rails conventions are fought. For the builder and the reviewer of a Ruby diff; the repo's config and existing code win over it.

Procedure

1. Discover the repo's conventions first. Call search_lore for Ruby conventions. Read .ruby-version/.tool-versions, Gemfile and Gemfile.lock, .rubocop.yml (and inherit_from/inherit_gem: Standard, rubocop-rails-omakase, a .rubocop_todo.yml), .standard.yml, type tooling (sorbet/, sig/ for RBS), .rspec or test/, config/application.rb (load_defaults), the job adapter and the CI workflow. Identify the service/query/form object patterns and factories. Copy a sibling class and its spec.
2. Pin the exact commands from CI or bin/ scripts (the run-tests and run-lint skills). Use the defaults below only when the repo defines none. Never add offences to .rubocop_todo.yml to pass.
3. Write the change with the idioms below, then walk the concurrency section for every shared object, record update, job, file and outbound call you touched.
4. Test each acceptance criterion's own behaviour. One request/model/job spec (or Minitest test) per AC that fails without your change, plus its error path. If the AC involves shared state or persistence, add a test that runs N threads against it (each with its own connection via ActiveRecord::Base.connection_pool.with_connection, and transactional fixtures disabled for that test) and asserts the invariant.
5. Verify, then stop. Done when: RuboCop/Standard is clean, the suite is green, a new migration migrates and rolls back, and every AC has a test. Record the output with the record-evidence skill; the runner submits the work.

Commands

• Gems are already installed; never run bundle install/bundle update/bundle add (installs need human approval; the hook does not catch these, the rule still holds). A missing gem goes in the evidence.
• Lint: bundle exec rubocop (or bin/rubocop, bundle exec standardrb).
• Tests: bundle exec rspec (one: bundle exec rspec spec/x_spec.rb:42) or bin/rails test (one: bin/rails test test/x_test.rb:42).
• Migrations: bin/rails db:migrate then bin/rails db:rollback and migrate again, only against the local development/test database; with none reachable, say so in the evidence.
• Security and types where configured: bundle exec brakeman, bundle exec bundle-audit check, bundle exec srb tc or bundle exec steep check.