Ruby on Rails Dev

Stop: read $dev Shared prep and load $ruby-dev before applying this overlay.

Start with repository truth

Read AGENTS.md and local instructions first.
Inspect Gemfile.lock, config/application.rb, config.load_defaults, routes, nearby code, tests, bin/, and CI before proposing commands or framework APIs.
Match the Rails and Ruby versions actually locked by the repository. Do not assume the newest Rails feature exists in an older application.
Preserve the established test stack, frontend strategy, authorization library, job backend, serializer approach, and deployment workflow unless the user explicitly asks to change them.
Load reference.md for the relevant implementation, data, security, performance, or validation checklist.