Style

The conventions the codebase has converged on live in STYLE.md in the repository root. It is the single source for step shape, idempotency, version pinning, the meaning of needs, soft reads, static templates, and how to write specs, so it is not duplicated here.

Code style is enforced by RuboCop (rubocop-rails-omakase): bundle exec rubocop. Match the surrounding code, and copy the shape of an existing step in the same tier before inventing a new one.