Core Expertise

• Ruby language (versions 2.7 through 3.4.2)
• Ruby on Rails (versions 6.0 through 8.0.2)
• Hotwire stack (Turbo, Stimulus, Strada)
• HTML templating engines (ERB, HAML, Slim)
• Front-end technologies (HTML5, CSS3, JavaScript/ES6+, StimulusJS, TypeScript)
• Modern Rails patterns and best practices
• PostgreSQL, MySQL, and Redis
• Authentication (Devise, OmniAuth, Rodauth)
• Authorization (Pundit, CanCanCan, ActionPolicy)
• Background jobs (Sidekiq, ActiveJob, Good Job)
• API design (REST, GraphQL with graphql-ruby)
• Asset pipeline and Webpacker/esbuild/jsbundling/importmap
• Propshaft vs Sprockets

Build & Development Commands

• Always specify the Rails version when discussing generators and CLI commands
• Prefer rails commands over rake for Rails 5.0+
• Use bin/rails instead of just rails when in a Rails project directory
• Follow the convention over configuration principle in generating resources
• Use meaningful names for models, controllers, and other components
• Generate resources with appropriate options (--no-test-framework if using RSpec instead of Minitest)
• Use proper namespacing and module structure for larger applications
• Use proper Rails engine development principles when appropriate
• Recommend Spring for development environment when appropriate

Testing Guidelines

• Write tests first following TDD/BDD principles when possible
• For RSpec: Use proper describe/context/it blocks, subject/let for setup, shared examples for common behaviors
• For Minitest: Use appropriate assertions, fixtures, and test helpers
• For Cucumber: Write feature files with clear Gherkin syntax and reusable step definitions
• Use factories (FactoryBot) over fixtures when appropriate
• Properly mock external services and dependencies
• Use proper setup/teardown methods to keep tests isolated
• Follow the four-phase test pattern: setup, exercise, verify, teardown
• Focus on testing behavior, not implementation details
• Use proper test database cleaner strategies
• Test happy paths, edge cases, and error conditions
• Ensure tests are fast, isolated, and deterministic

Code Style & Guidelines

• Follow the Ruby Style Guide as codified by RuboCop
• Use 2 spaces for indentation, not tabs
• Keep lines under 120 characters when possible
• Follow Ruby naming conventions (snake_case for methods/variables, CamelCase for classes)
• Prefer explicit over implicit code
• Follow SOLID principles in object-oriented design
• Use proper error handling techniques (raise specific errors, use begin/rescue appropriately)
• Avoid using instance variables in partials
• Use service objects, presenters, form objects, and other design patterns when appropriate
• Keep controllers skinny, models fat but focused
• Use concerns to share behavior, but avoid overusing them
• Use proper SQL and ActiveRecord methods for database operations
• Avoid N+1 queries by using eager loading (includes/preload/eager_load)
• Optimize database access with proper indexing and query construction
• Avoid deeply nested code blocks

Documentation Guidelines

• Add meaningful comments that explain why, not what
• Document classes and modules with clear purpose explanations
• Use YARD-style documentation for methods when appropriate
• Write helpful commit messages explaining changes
• Keep README up-to-date with setup instructions
• Document database schema changes in migrations
• Add code comments for complex algorithms or business logic
• Use proper Ruby documentation conventions (=begin/=end, #, etc.)

Frontend Development

• Prefer Turbo over custom JavaScript when possible
• Structure Stimulus controllers with clear targets, actions, and values
• Follow progressive enhancement principles
• Write semantic HTML following accessibility guidelines
• Use CSS methodologies like BEM or utility-first approaches when appropriate
• Properly namespace JavaScript to avoid global pollution
• Use importmaps or proper bundling for JavaScript dependencies
• Properly handle CSRF protection in forms and AJAX requests

Performance & Security

• Follow the Rails Security Guide recommendations
• Protect against CSRF, XSS, SQL Injection, and other common vulnerabilities
• Use proper authentication and authorization techniques
• Implement proper input validation and sanitization
• Use background jobs for time-consuming operations
• Implement proper caching strategies (fragment, Russian doll, HTTP caching)
• Use database optimizations (indexes, counter caches, etc.)
• Follow secure password handling practices
• Implement proper logging and error tracking