Ruby on Rails Reference

Bundled, offline snapshot of the official Rails documentation:

• references/guides/ — 54 Rails Guides (the conceptual "how Rails works" docs)
• references/api/ — 80 core API class pages from api.rubyonrails.org (signatures, methods, options)
• references/overview.md — the Rails framework overview (what each component does)

Source: crawled from guides.rubyonrails.org and api.rubyonrails.org. Treat these files as the source of truth for Rails behavior, defaults, and method signatures. When a question is answerable from a bundled file, load that file with Read instead of fetching the web or answering from memory — Rails defaults change between versions and the bundled docs are the snapshot in hand.

How to use this skill

1. Identify the Rails component/topic from the user's question (the map below).
2. Read the matching references/guides/<file> for concepts/behavior, and/or references/api/<Class>.md for exact method signatures and options.
3. Quote/apply the specific behavior; cite the guide name. Don't paraphrase from recall when the file is right here.

If unsure which component owns a concept, read references/overview.md first — it summarizes the responsibility of each Rails framework (Model/View/Controller layers + Action Mailer, Active Job, Action Cable, Active Storage, Action Text, Active Support).

Topic → guide map

Getting started / project setup

• getting_started.md — first app, full walkthrough
• install_ruby_on_rails.md, development_dependencies_install.md — installation
• command_line.md — rails/rake commands, runners, consoles
• configuring.md — config files, initializers, config.* options
• generators.md — writing and customizing generators

Models — Active Record (load references/api/ActiveRecord_*.md for signatures)

• active_record_basics.md — models, CRUD, conventions → API: ActiveRecord_Base.md, ActiveRecord_Persistence.md, ActiveRecord_Core.md
• active_record_migrations.md — schema changes → API: ActiveRecord_Migration.md
• active_record_validations.md — validations → API: ActiveRecord_Validations.md, ActiveModel_Validations.md, ActiveModel_Errors.md
• active_record_callbacks.md — lifecycle hooks → API: ActiveRecord_Callbacks.md
• association_basics.md — has_many/belongs_to/etc. → API: ActiveRecord_Associations.md, ActiveRecord_Associations_ClassMethods.md, ActiveRecord_NestedAttributes.md
• active_record_querying.md — query interface → API: ActiveRecord_FinderMethods.md, ActiveRecord_Scoping.md, ActiveRecord_Sanitization.md
• active_record_multiple_databases.md — multi-DB → API: ActiveRecord_ConnectionHandling.md
• active_record_composite_primary_keys.md, active_record_encryption.md (→ ActiveRecord_Encryption_EncryptableRecord.md), active_record_postgresql.md
• Transactions/locking → API: ActiveRecord_Transactions.md, ActiveRecord_Locking_Optimistic.md, ActiveRecord_Locking_Pessimistic.md
• active_model_basics.md — Active Model for non-DB objects → API: ActiveModel_API.md, ActiveModel_AttributeMethods.md, ActiveModel_Dirty.md, ActiveModel_Serialization.md

Views — Action View

• action_view_overview.md, action_view_helpers.md — templates and helpers
• layouts_and_rendering.md — render/redirect/layouts
• form_helpers.md — form_with, form builders, nested forms

Controllers — Action Controller

• action_controller_overview.md — params, sessions, filters, strong params → API: ActionController_Base.md, ActionController_Parameters.md
• action_controller_advanced_topics.md — streaming, rescue, etc.
• routing.md — the router, resources, constraints
• Sessions/cookies → API: ActionDispatch_Session_CookieStore.md

Other framework components

• action_mailer_basics.md, action_mailbox_basics.md — outbound/inbound email
• action_text_overview.md — rich text
• action_cable_overview.md — WebSockets
• active_job_basics.md — background jobs
• active_storage_overview.md — file attachments
• active_support_core_extensions.md, active_support_instrumentation.md — Active Support helpers + instrumentation events
• working_with_javascript_in_rails.md, asset_pipeline.md — front-end assets, import maps

Cross-cutting concerns

• i18n.md — internationalization
• security.md — security guide (CSRF, mass assignment, injection)
• caching_with_rails.md — fragment/Russian-doll caching
• error_reporting.md, debugging_rails_applications.md — diagnostics
• autoloading_and_reloading_constants.md — Zeitwerk autoloading
• threading_and_code_execution.md — concurrency, the executor/reloader
• sign_up_and_settings.md — built-in authentication generator example

Testing

• testing.md — the full testing guide (model/controller/system/integration tests, fixtures)

Deploy / maintain / extend

• tuning_performance_for_deployment.md — app servers, threads, YJIT, pooling
• upgrading_ruby_on_rails.md, maintenance_policy.md — version upgrades and support windows
• engines.md, plugins.md, rails_on_rack.md, initialization.md — extending Rails internals
• api_app.md — API-only Rails apps

Contributing to Rails (only when the task is patching Rails itself)

• contributing_to_ruby_on_rails.md, api_documentation_guidelines.md, ruby_on_rails_guides_guidelines.md

Notes & limits

• Snapshot, not live. These are crawled at a point in time (Rails ~8.x edge guides). For a version-specific question, confirm the target Rails version; if it differs materially, note that the bundled snapshot may not match and fall back to a targeted web fetch.
• API coverage is partial. references/api/ holds the most-used Active Record / Active Model / Action Controller classes (depth-2 from the API index), not the entire API tree. If a needed class isn't bundled, the guides usually cover the behavior; otherwise fetch https://api.rubyonrails.org/classes/<Class>.html.
• Don't dump whole files into context. These guides are large. Read the single relevant file (and use offset/limit or grep within it) rather than loading several at once.