Interview the developer about their Ruby on Rails project (app type, database, frontend stack, background jobs, deployment target, traffic profile, compliance, current Rails version) and then route to the right downstream rails-skills. Use at the start of any new Rails work session, when the user says they want to "start a new Rails app", "set up a Rails project", "scaffold Rails", "build a Rails API", "build a Rails monolith", "build a Rails 8 app", or anytime they reference rails-skills without specifying which skill they want. Also use when reviewing or auditing an existing Rails codebase to determine which skills apply. This is the entry point of the rails-skills pack — almost every Rails task should start here.
Generate project-specific Claude Skills for THIS Rails app — interview the codebase (domain models, workflows, multi-tenancy, auth, test + verification loop, branch rules, deploy) and emit starter SKILL.md files under the user's own .claude/skills/ that encode their product's conventions. Use when the user says "create skills for my app", "make project-specific skills", "scaffold local skills", "the generic rails-skills don't know my domain", "teach the agent my codebase conventions", "generate a skill for my <feature>", or wants the agent to learn their app's tenant rules / domain workflows / test gates rather than generic Rails advice.
Idiomatic ActiveRecord patterns for Ruby on Rails — associations (belongs_to/has_many/has_one/has_many :through), counter_cache, polymorphic, STI vs delegated_type, scopes vs class methods, callbacks vs after_commit, find vs find_by vs where.first, includes vs preload vs eager_load, pluck vs select, exists? vs any?, batch processing with find_each, and fat-models-with-concerns. Use whenever the user writes or reviews ActiveRecord models, asks why a Rails query is slow or wrong, mentions includes/preload/eager_load, says "callback", references scopes, or is generating model code. Also use proactively when reading any Rails model file (app/models/*.rb).
Detect, diagnose, and eliminate N+1 queries in Ruby on Rails. Use when the user mentions slow Rails endpoints, slow queries, "N+1", Bullet, prosopite, includes/preload/eager_load, eager loading, query count is high, page is slow to render, or asks why a Rails controller is slow. Also use proactively when reviewing any controller action that iterates a collection and accesses associations, or any view that loops and calls `.author`, `.comments.count`, etc. Bundles a Bullet config script and an EXPLAIN ANALYZE reference for Rails devs.
Decide when Rails logic stays in the model and when it earns a service object. Use when the user asks about service objects, fat models, "where does this logic go", refactoring a controller, extracting business logic, the Result pattern, interactor gem, dry-monads, command objects, or is about to write a class ending in Service / Manager / Handler / Processor. Also use proactively when reviewing any controller action with more than ~10 lines of business logic, or any model file exceeding ~200 lines.
RSpec testing for Ruby on Rails — pyramid shape (lots of model + request specs, fewer system specs), FactoryBot patterns, let vs let! vs before, shared examples, VCR for external HTTP, system specs with Capybara + Cuprite, transactional vs truncation strategy, parallel testing, SimpleCov coverage. Use when writing or reviewing Rails tests, the user mentions RSpec, FactoryBot, Capybara, Cuprite, VCR, system specs, request specs, model specs, fixtures, factories, flaky tests, slow test suite, parallel_rspec, or asks for help with rails_helper / spec_helper. Bundles drop-in spec_helper.rb + rails_helper.rb + .rspec templates.
Write zero-downtime database migrations for Ruby on Rails — strong_migrations rules, the add-column / set-default / backfill / enforce-NOT-NULL multi-deploy split, disable_ddl_transaction!, concurrent index creation on PostgreSQL, find_each batching, why change_column is dangerous, the deploy/migrate/deploy sequencing. Use when writing or reviewing Rails migrations, adding a column to a large table, removing or renaming columns, adding NOT NULL or foreign keys, adding indexes on big tables, when the user mentions strong_migrations, zero downtime, migration locks, deploy ordering, or asks how to backfill a column safely.
Design REST APIs in Ruby on Rails — URL versioning over Accept-header, jsonapi-serializer / alba / blueprinter, pagy pagination, JWT auth for stateless / session cookies for first-party SPAs, rack-attack rate limiting, structured error responses, OpenAPI/Swagger via rswag, CORS configuration. Use when building or reviewing a Rails::API app, adding JSON endpoints to a monolith, the user mentions API versioning, serializers, JSON serialization, JWT, rack-attack, rate limits, pagination, OpenAPI, Swagger, rswag, REST API design, CORS, or asks how to structure /api/v1 routes.