Migrating From Rails

Status: not executed end to end. No Rails app has been cut over by following this page yet; it flips to executed on evidence from an adopter's measured run.

Migrating from Rails

The concept map for a Rails app. The runbook — phases, exit conditions, stop conditions — is Migrating an existing app; this page says what each Rails term becomes. As of 2026-11, against Rails 8 (guides.rubyonrails.org).

Concept map

Rails	Ultimate
config/routes.rb + a controller action that renders	a route file: Routes and render modes
a controller action that writes	an action: Actions
an Active Record model	an entity(): Entities and migrations
a scope, a where chain	a query: Queries and live queries
db/migrate/*.rb, schema.rb	x db gen "<name>", then x db migrate
rails generate	x g <kind> <name> (CLI reference)
Active Job, Sidekiq	a job: Jobs and workflows
whenever, sidekiq-cron	a task: Scheduled tasks
Devise, has_secure_password	Auth
Pundit, CanCanCan	a policy: Policies and authz
Action Cable, Turbo Streams	a live query: Realtime
Action Mailer	Mail
Active Storage	Storage and uploads
ActiveAdmin, Administrate	Admin dashboard
config/locales/*.yml	one flat catalog per locale: I18n
RSpec, Minitest	Testing
bin/rails server	x dev
bin/rails test + CI	x verify

What does not map

Rails	Why
Ruby and its gems	Bun only. Nothing runs Ruby; a gem's behaviour is rewritten or bought as a service
MySQL, SQLite	Postgres only, by design: Home
ERB, Hotwire, Stimulus	pages render with SolidJS; interactive parts are islands (Routes and render modes). No converter
model callbacks (before_save, after_commit)	no implicit hooks: the write is an action or a mutator that says what it does (Actions)
SAML (devise_saml_authenticatable)	not shipped: put an OIDC bridge in front (Auth)

Schema adoption

Rails ids are bigint sequences and timestamps are created_at / updated_at. Phase 1 of the runbook declares the existing tables as entities with the physical-name overrides and type map it gives, then x db gen until x verify --only drift agrees: Migrating an existing app.

Identity cutover

Rails stores	Branch
password_digest (has_secure_password) or Devise's encrypted_password — bcrypt by default	proceed: verified natively, rewritten as argon2id on first login (Migrating an existing app)
the session: an encrypted cookie keyed by secret_key_base	bridge it with your own verifier behind configureAuthenticator(), or keep the Rails login until every user has signed in once (Auth)