Guarantee your agents and your team follow your conventions. ArchSpec turns them into static analysis checks that run in CI on every change. No AI involved, just Prism.
controllers.can_only_use :models, :services
models.cannot_use :controllers
services.cannot_call :render, :redirect_to
[error] services must not call #render [methods.forbid]
app/services/create_user.rb:7:5
→ 7 │ render :new
│ ^~~~~~~~~~~
note: CreateUser calls render
architecture :rails
jobs.cannot_reference_constants "Current"
component :commands, in: "app/commands/**/*.rb"
commands.must_implement :call
component :queries, in: "app/queries/**/*.rb"
queries.cannot_call :save!, :update!, :destroy!
component :services, in: "app/services/**/*.rb"
services.must_be_empty because: "rich models"
component :billing, in: "packs/billing/**/*.rb"
component :catalog, in: "packs/catalog/**/*.rb"
billing.can_only_use :catalog
archspec check reads your code with Prism, with no app boot and no database. Fast enough for CI, a git hook, and every change an agent makes.
Allowed and forbidden references between layers and packs, dependency direction and cycles, controller APIs kept out of models, method protocols, and one-shot command objects.
Start from one that is already written: Rails, vanilla Rails, layered, hexagonal, clean, modular monolith, CQRS, event-driven. Or compose your own rules in plain Ruby.