language plugin

syrus_rails

`syrus_rails` is a Syrus plugin gem that bundles Rails-*framework*-specific capabilities into a single `PluginRegistry.register` call (registered manifest name `syrus-rails`). It lives at `plugins/rails/` inside the Syrus repository and is the primary integration point for Ruby on Rails repositories. Ruby-generic capabilities that aren't specific to Rails — RSpec grader failure detail, RSpec output parsing, SimpleCov coverage analysis, and Gemfile prepare detection — live in the separate `ruby` plugin (`plugins/ruby/`) instead, so non-Rails Ruby projects (gems, Sinatra apps, plain scripts) can use them too. `syrus_rails` declares `depends_on: [ "ruby" ]`: enabling `syrus_rails` in Admin → Plugins cascades to enable `ruby`, and disabling `ruby` while `syrus_rails` is enabled surfaces a confirm-and-cascade-disable prompt. See `config/syrus_docs/plugins.md` for the general `depends_on` mechanism.

syrus_railsSource

syrus_rails

syrus_rails is a Syrus plugin gem that bundles Rails-*framework*-specific capabilities into a single PluginRegistry.register call (registered manifest name syrus-rails). It lives at plugins/rails/ inside the Syrus repository and is the primary integration point for Ruby on Rails repositories.

Ruby-generic capabilities that aren't specific to Rails — RSpec grader failure detail, RSpec output parsing, SimpleCov coverage analysis, and Gemfile prepare detection — live in the separate ruby plugin (plugins/ruby/) instead, so non-Rails Ruby projects (gems, Sinatra apps, plain scripts) can use them too. syrus_rails declares depends_on: [ "ruby" ]: enabling syrus_rails in Admin → Plugins cascades to enable ruby, and disabling ruby while syrus_rails is enabled surfaces a confirm-and-cascade-disable prompt. See config/syrus_docs/plugins.md for the general depends_on mechanism.

What it provides

Extension point	What it does
`:preview_provider`	Configures the Syrus preview host to run `bin/rails server`, seed via `db:create db:migrate db:seed`, health-check `/up` (falling back to `/` when the repo's `config/routes.rb` doesn't map `rails/health#show`), and tail `log/development.log`
`:mcp_tool_set`	Rails schema/migration/route introspection tools for workflow agents
`:artifact_renderer`	`SchemaErdRenderer` and `MigrationDiffRenderer`, mapping `submit_artifact` payload types to reviewer-facing ERD/migration-diff views
`:prompt_injector`	Adds Rails-specific guidance (schema/migration awareness) to the implementing agent's system prompt

Auto-detection

The plugin activates for repositories that contain all three of:

Gemfile
config/application.rb
bin/rails

Detection is handled by SyrusRails::PreviewProvider#detect?.

Loading the plugin

Call SyrusRails.register! at Syrus boot time (e.g. in a Rails initializer or at the top of the worker entry point):

require "syrus_rails"
SyrusRails.register!

After registration, Syrus::PluginRegistry.providers_for(:preview_provider) includes a SyrusRails::PreviewProvider instance. Syrus::PreviewProviderResolver.for(repo_path) returns that instance for any Rails repository and nil otherwise.

Preview hosting with SQLite

The preview host runs the Rails server as a long-lived child process. Because no companion database container is available, the repository's config/database.yml must use adapter: sqlite3 for the development environment:

default: &default
  adapter: sqlite3
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  timeout: 5000

development:
  <<: *default
  database: db/development.sqlite3

Rails previews install JavaScript dependencies when a package-manager lockfile is present and start npm run dev alongside bin/rails server when the repo's package.json actually defines a dev script (a package.json present for other tooling, with no dev script, is left alone rather than launching a doomed npm run dev). They also set VITE_RUBY_SKIP_PROXY=false so vite-ruby generates same-origin asset URLs. Without those preview-specific guardrails, apps can leak http://localhost:<vite-port> asset URLs that point at the operator's browser machine instead of the preview host and render as a blank page.

The provider exposes log/development.log and log/vite.log to the preview log API and the read_preview_log MCP tool.

Postgres preview environments are not yet supported.

Running tests

From the repo root:

bin/rspec spec/plugins/rails/ spec/syrus/plugin_registry_spec.rb

Adding more extension points

Each new extension point follows the same pattern:

Add a class to plugins/rails/lib/syrus_rails/<name>.rb that includes the matching Syrus::Plugin::<Interface> module.
Add a PluginRegistry.register(:<extension_point>, <ClassName>.new) call inside SyrusRails.register!.
Add a spec under spec/plugins/rails/.