feat(skills): Add dhh-rails-style skill for 37signals Rails conventions

Router-pattern skill with sectioned references:
- controllers.md: REST mapping, concerns, Turbo, API patterns
- models.md: Concerns, state records, callbacks, scopes
- frontend.md: Turbo, Stimulus, CSS architecture
- architecture.md: Routing, auth, jobs, caching, config
- gems.md: What they use vs avoid, decision framework

Based on analysis of Fizzy (Campfire) codebase.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/compound-engineering/skills/dhh-rails-style/references/architecture.md

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+# Architecture - DHH Rails Style
+
+<routing>
+## Routing
+
+Everything maps to CRUD. Nested resources for related actions:
+
+```ruby
+Rails.application.routes.draw do
+  resources :boards do
+    resources :cards do
+      resource :closure
+      resource :goldness
+      resource :not_now
+      resources :assignments
+      resources :comments
+    end
+  end
+end
+```
+
+**Multi-tenancy** via URL (not subdomain):
+```ruby
+# /{account_id}/boards/...
+scope "/:account_id" do
+  resources :boards
+end
+```
+
+Benefits:
+- No subdomain DNS complexity
+- Deep links work naturally
+- Middleware extracts account_id, moves to SCRIPT_NAME
+- `Current.account` available everywhere
+</routing>
+
+<authentication>
+## Authentication
+
+Custom passwordless magic link auth (~150 lines total):
+
+```ruby
+# app/models/session.rb
+class Session < ApplicationRecord
+  belongs_to :user
+
+  before_create { self.token = SecureRandom.urlsafe_base64(32) }
+end
+
+# app/models/magic_link.rb
+class MagicLink < ApplicationRecord
+  belongs_to :user
+
+  before_create do
+    self.code = SecureRandom.random_number(100_000..999_999).to_s
+    self.expires_at = 15.minutes.from_now
+  end
+
+  def expired?
+    expires_at < Time.current
+  end
+end
+```
+
+**Why not Devise:**
+- ~150 lines vs massive dependency
+- No password storage liability
+- Simpler UX for users
+- Full control over flow
+
+**Bearer token** for APIs:
+```ruby
+module Authentication
+  extend ActiveSupport::Concern
+
+  included do
+    before_action :authenticate
+  end
+
+  private
+    def authenticate
+      if bearer_token = request.headers["Authorization"]&.split(" ")&.last
+        Current.session = Session.find_by(token: bearer_token)
+      else
+        Current.session = Session.find_by(id: cookies.signed[:session_id])
+      end
+
+      redirect_to login_path unless Current.session
+    end
+end
+```
+</authentication>
+
+<background_jobs>
+## Background Jobs
+
+Jobs are shallow wrappers calling model methods:
+
+```ruby
+class NotifyWatchersJob < ApplicationJob
+  def perform(card)
+    card.notify_watchers
+  end
+end
+```
+
+**Naming convention:**
+- `_later` suffix for async: `card.notify_watchers_later`
+- `_now` suffix for immediate: `card.notify_watchers_now`
+
+```ruby
+module Watchable
+  def notify_watchers_later
+    NotifyWatchersJob.perform_later(self)
+  end
+
+  def notify_watchers_now
+    NotifyWatchersJob.perform_now(self)
+  end
+
+  def notify_watchers
+    watchers.each do |watcher|
+      WatcherMailer.notification(watcher, self).deliver_later
+    end
+  end
+end
+```
+
+**Database-backed** with Solid Queue:
+- No Redis required
+- Same transactional guarantees as your data
+- Simpler infrastructure
+</background_jobs>
+
+<current_attributes>
+## Current Attributes
+
+Use `Current` for request-scoped state:
+
+```ruby
+# app/models/current.rb
+class Current < ActiveSupport::CurrentAttributes
+  attribute :session, :user, :account, :request_id
+
+  delegate :user, to: :session, allow_nil: true
+
+  def account=(account)
+    super
+    Time.zone = account&.time_zone || "UTC"
+  end
+end
+```
+
+Set in controller:
+```ruby
+class ApplicationController < ActionController::Base
+  before_action :set_current_request
+
+  private
+    def set_current_request
+      Current.session = authenticated_session
+      Current.account = Account.find(params[:account_id])
+      Current.request_id = request.request_id
+    end
+end
+```
+
+Use throughout app:
+```ruby
+class Card < ApplicationRecord
+  belongs_to :creator, default: -> { Current.user }
+end
+```
+</current_attributes>
+
+<caching>
+## Caching
+
+**HTTP caching** with ETags:
+```ruby
+fresh_when etag: [@card, Current.user.timezone]
+```
+
+**Fragment caching:**
+```erb
+<% cache card do %>
+  <%= render card %>
+<% end %>
+```
+
+**Russian doll caching:**
+```erb
+<% cache @board do %>
+  <% @board.cards.each do |card| %>
+    <% cache card do %>
+      <%= render card %>
+    <% end %>
+  <% end %>
+<% end %>
+```
+
+**Cache invalidation** via `touch: true`:
+```ruby
+class Card < ApplicationRecord
+  belongs_to :board, touch: true
+end
+```
+
+**Solid Cache** - database-backed:
+- No Redis required
+- Consistent with application data
+- Simpler infrastructure
+</caching>
+
+<configuration>
+## Configuration
+
+**ENV.fetch with defaults:**
+```ruby
+# config/application.rb
+config.active_job.queue_adapter = ENV.fetch("QUEUE_ADAPTER", "solid_queue").to_sym
+config.cache_store = ENV.fetch("CACHE_STORE", "solid_cache").to_sym
+```
+
+**Multiple databases:**
+```yaml
+# config/database.yml
+production:
+  primary:
+    <<: *default
+  cable:
+    <<: *default
+    migrations_paths: db/cable_migrate
+  queue:
+    <<: *default
+    migrations_paths: db/queue_migrate
+  cache:
+    <<: *default
+    migrations_paths: db/cache_migrate
+```
+
+**Switch between SQLite and MySQL via ENV:**
+```ruby
+adapter = ENV.fetch("DATABASE_ADAPTER", "sqlite3")
+```
+
+**CSP extensible via ENV:**
+```ruby
+config.content_security_policy do |policy|
+  policy.default_src :self
+  policy.script_src :self, *ENV.fetch("CSP_SCRIPT_SRC", "").split(",")
+end
+```
+</configuration>
+
+<testing>
+## Testing
+
+**Minitest**, not RSpec:
+```ruby
+class CardTest < ActiveSupport::TestCase
+  test "closing a card creates a closure" do
+    card = cards(:one)
+
+    card.close
+
+    assert card.closed?
+    assert_not_nil card.closure
+  end
+end
+```
+
+**Fixtures** instead of factories:
+```yaml
+# test/fixtures/cards.yml
+one:
+  title: First Card
+  board: main
+  creator: alice
+
+two:
+  title: Second Card
+  board: main
+  creator: bob
+```
+
+**Integration tests** for controllers:
+```ruby
+class CardsControllerTest < ActionDispatch::IntegrationTest
+  test "closing a card" do
+    card = cards(:one)
+    sign_in users(:alice)
+
+    post card_closure_path(card)
+
+    assert_response :success
+    assert card.reload.closed?
+  end
+end
+```
+
+**Tests ship with features** - same commit, not TDD-first but together.
+
+**Regression tests for security fixes** - always.
+</testing>
+
+<events>
+## Event Tracking
+
+Events are the single source of truth:
+
+```ruby
+class Event < ApplicationRecord
+  belongs_to :creator, class_name: "User"
+  belongs_to :eventable, polymorphic: true
+
+  serialize :particulars, coder: JSON
+end
+```
+
+**Eventable concern:**
+```ruby
+module Eventable
+  extend ActiveSupport::Concern
+
+  included do
+    has_many :events, as: :eventable, dependent: :destroy
+  end
+
+  def record_event(action, particulars = {})
+    events.create!(
+      creator: Current.user,
+      action: action,
+      particulars: particulars
+    )
+  end
+end
+```
+
+**Webhooks driven by events** - events are the canonical source.
+</events>

plugins/compound-engineering/skills/dhh-rails-style/references/controllers.md

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+# Controllers - DHH Rails Style
+
+<rest_mapping>
+## Everything Maps to CRUD
+
+Custom actions become new resources. Instead of verbs on existing resources, create noun resources:
+
+```ruby
+# Instead of this:
+POST /cards/:id/close
+DELETE /cards/:id/close
+POST /cards/:id/archive
+
+# Do this:
+POST /cards/:id/closure      # create closure
+DELETE /cards/:id/closure    # destroy closure
+POST /cards/:id/archival     # create archival
+```
+
+**Real examples from 37signals:**
+```ruby
+resources :cards do
+  resource :closure       # closing/reopening
+  resource :goldness      # marking important
+  resource :not_now       # postponing
+  resources :assignments  # managing assignees
+end
+```
+
+Each resource gets its own controller with standard CRUD actions.
+</rest_mapping>
+
+<controller_concerns>
+## Concerns for Shared Behavior
+
+Controllers use concerns extensively. Common patterns:
+
+**CardScoped** - loads @card, @board, provides render_card_replacement
+```ruby
+module CardScoped
+  extend ActiveSupport::Concern
+
+  included do
+    before_action :set_card
+  end
+
+  private
+    def set_card
+      @card = Card.find(params[:card_id])
+      @board = @card.board
+    end
+
+    def render_card_replacement
+      render turbo_stream: turbo_stream.replace(@card)
+    end
+end
+```
+
+**BoardScoped** - loads @board
+**CurrentRequest** - populates Current with request data
+**CurrentTimezone** - wraps requests in user's timezone
+**FilterScoped** - handles complex filtering
+**TurboFlash** - flash messages via Turbo Stream
+**ViewTransitions** - disables on page refresh
+</controller_concerns>
+
+<turbo_responses>
+## Turbo Stream Responses
+
+Use Turbo Streams for partial updates:
+
+```ruby
+class Cards::ClosuresController < ApplicationController
+  include CardScoped
+
+  def create
+    @card.close
+    render_card_replacement
+  end
+
+  def destroy
+    @card.reopen
+    render_card_replacement
+  end
+end
+```
+
+For complex updates, use morphing:
+```ruby
+render turbo_stream: turbo_stream.morph(@card)
+```
+</turbo_responses>
+
+<api_patterns>
+## API Design
+
+Same controllers, different format. Convention for responses:
+
+```ruby
+def create
+  @card = Card.create!(card_params)
+
+  respond_to do |format|
+    format.html { redirect_to @card }
+    format.json { head :created, location: @card }
+  end
+end
+
+def update
+  @card.update!(card_params)
+
+  respond_to do |format|
+    format.html { redirect_to @card }
+    format.json { head :no_content }
+  end
+end
+
+def destroy
+  @card.destroy
+
+  respond_to do |format|
+    format.html { redirect_to cards_path }
+    format.json { head :no_content }
+  end
+end
+```
+
+**Status codes:**
+- Create: 201 Created + Location header
+- Update: 204 No Content
+- Delete: 204 No Content
+- Bearer token authentication
+</api_patterns>
+
+<http_caching>
+## HTTP Caching
+
+Extensive use of ETags and conditional GETs:
+
+```ruby
+class CardsController < ApplicationController
+  def show
+    @card = Card.find(params[:id])
+    fresh_when etag: [@card, Current.user.timezone]
+  end
+
+  def index
+    @cards = @board.cards.preloaded
+    fresh_when etag: [@cards, @board.updated_at]
+  end
+end
+```
+
+Key insight: Times render server-side in user's timezone, so timezone must affect the ETag to prevent serving wrong times to other timezones.
+
+**ApplicationController global etag:**
+```ruby
+class ApplicationController < ActionController::Base
+  etag { "v1" }  # Bump to invalidate all caches
+end
+```
+
+Use `touch: true` on associations for cache invalidation.
+</http_caching>

plugins/compound-engineering/skills/dhh-rails-style/references/frontend.md

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+# Frontend - DHH Rails Style
+
+<turbo_patterns>
+## Turbo Patterns
+
+**Turbo Streams** for partial updates:
+```erb
+<%# app/views/cards/closures/create.turbo_stream.erb %>
+<%= turbo_stream.replace @card %>
+```
+
+**Morphing** for complex updates:
+```ruby
+render turbo_stream: turbo_stream.morph(@card)
+```
+
+**Fragment caching** with `cached: true`:
+```erb
+<%= render partial: "card", collection: @cards, cached: true %>
+```
+
+**No ViewComponents** - standard partials work fine.
+</turbo_patterns>
+
+<stimulus_controllers>
+## Stimulus Controllers
+
+52 controllers in Fizzy, split 62% reusable, 38% domain-specific.
+
+**Characteristics:**
+- Single responsibility per controller
+- Configuration via values/classes
+- Events for communication
+- Private methods with #
+- Most under 50 lines
+
+**Examples:**
+
+```javascript
+// copy-to-clipboard (25 lines)
+import { Controller } from "@hotwired/stimulus"
+
+export default class extends Controller {
+  static values = { content: String }
+
+  copy() {
+    navigator.clipboard.writeText(this.contentValue)
+    this.#showFeedback()
+  }
+
+  #showFeedback() {
+    this.element.classList.add("copied")
+    setTimeout(() => this.element.classList.remove("copied"), 1500)
+  }
+}
+```
+
+```javascript
+// auto-click (7 lines)
+import { Controller } from "@hotwired/stimulus"
+
+export default class extends Controller {
+  connect() {
+    this.element.click()
+  }
+}
+```
+
+```javascript
+// toggle-class (31 lines)
+import { Controller } from "@hotwired/stimulus"
+
+export default class extends Controller {
+  static classes = ["toggle"]
+  static values = { open: { type: Boolean, default: false } }
+
+  toggle() {
+    this.openValue = !this.openValue
+  }
+
+  openValueChanged() {
+    this.element.classList.toggle(this.toggleClass, this.openValue)
+  }
+}
+```
+
+```javascript
+// dialog (64 lines) - for modal dialogs
+// local-save (59 lines) - localStorage persistence
+// drag-and-drop (150 lines) - the largest, still reasonable
+```
+</stimulus_controllers>
+
+<css_architecture>
+## CSS Architecture
+
+Vanilla CSS with modern features, no preprocessors.
+
+**CSS @layer** for cascade control:
+```css
+@layer reset, base, components, modules, utilities;
+
+@layer reset {
+  *, *::before, *::after { box-sizing: border-box; }
+}
+
+@layer base {
+  body { font-family: var(--font-sans); }
+}
+
+@layer components {
+  .btn { /* button styles */ }
+}
+
+@layer modules {
+  .card { /* card module styles */ }
+}
+
+@layer utilities {
+  .hidden { display: none; }
+}
+```
+
+**OKLCH color system** for perceptual uniformity:
+```css
+:root {
+  --color-primary: oklch(60% 0.15 250);
+  --color-success: oklch(65% 0.2 145);
+  --color-warning: oklch(75% 0.15 85);
+  --color-danger: oklch(55% 0.2 25);
+}
+```
+
+**Dark mode** via CSS variables:
+```css
+:root {
+  --bg: oklch(98% 0 0);
+  --text: oklch(20% 0 0);
+}
+
+@media (prefers-color-scheme: dark) {
+  :root {
+    --bg: oklch(15% 0 0);
+    --text: oklch(90% 0 0);
+  }
+}
+```
+
+**Native CSS nesting:**
+```css
+.card {
+  padding: var(--space-4);
+
+  & .title {
+    font-weight: bold;
+  }
+
+  &:hover {
+    background: var(--bg-hover);
+  }
+}
+```
+
+**~60 minimal utilities** vs Tailwind's hundreds.
+
+**Modern features used:**
+- `@starting-style` for enter animations
+- `color-mix()` for color manipulation
+- `:has()` for parent selection
+- Logical properties (`margin-inline`, `padding-block`)
+- Container queries
+</css_architecture>
+
+<view_patterns>
+## View Patterns
+
+**Standard partials** - no ViewComponents:
+```erb
+<%# app/views/cards/_card.html.erb %>
+<article id="<%= dom_id(card) %>" class="card">
+  <%= render "cards/header", card: card %>
+  <%= render "cards/body", card: card %>
+  <%= render "cards/footer", card: card %>
+</article>
+```
+
+**Fragment caching:**
+```erb
+<% cache card do %>
+  <%= render "cards/card", card: card %>
+<% end %>
+```
+
+**Collection caching:**
+```erb
+<%= render partial: "card", collection: @cards, cached: true %>
+```
+
+**Simple component naming** - no strict BEM:
+```css
+.card { }
+.card .title { }
+.card .actions { }
+.card.golden { }
+.card.closed { }
+```
+</view_patterns>

plugins/compound-engineering/skills/dhh-rails-style/references/gems.md

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+# Gems - DHH Rails Style
+
+<what_they_use>
+## What 37signals Uses
+
+**Core Rails stack:**
+- turbo-rails, stimulus-rails, importmap-rails
+- propshaft (asset pipeline)
+
+**Database-backed services (Solid suite):**
+- solid_queue - background jobs
+- solid_cache - caching
+- solid_cable - WebSockets/Action Cable
+
+**Authentication & Security:**
+- bcrypt (for any password hashing needed)
+
+**Their own gems:**
+- geared_pagination (cursor-based pagination)
+- lexxy (rich text editor)
+- mittens (mailer utilities)
+
+**Utilities:**
+- rqrcode (QR code generation)
+- redcarpet + rouge (Markdown rendering)
+- web-push (push notifications)
+
+**Deployment & Operations:**
+- kamal (Docker deployment)
+- thruster (HTTP/2 proxy)
+- mission_control-jobs (job monitoring)
+- autotuner (GC tuning)
+</what_they_use>
+
+<what_they_avoid>
+## What They Deliberately Avoid
+
+**Authentication:**
+```
+devise → Custom ~150-line auth
+```
+Why: Full control, no password liability with magic links, simpler.
+
+**Authorization:**
+```
+pundit/cancancan → Simple role checks in models
+```
+Why: Most apps don't need policy objects. A method on the model suffices:
+```ruby
+class Board < ApplicationRecord
+  def editable_by?(user)
+    user.admin? || user == creator
+  end
+end
+```
+
+**Background Jobs:**
+```
+sidekiq → Solid Queue
+```
+Why: Database-backed means no Redis, same transactional guarantees.
+
+**Caching:**
+```
+redis → Solid Cache
+```
+Why: Database is already there, simpler infrastructure.
+
+**Search:**
+```
+elasticsearch → Custom sharded search
+```
+Why: Built exactly what they need, no external service dependency.
+
+**View Layer:**
+```
+view_component → Standard partials
+```
+Why: Partials work fine. ViewComponents add complexity without clear benefit for their use case.
+
+**API:**
+```
+GraphQL → REST with Turbo
+```
+Why: REST is sufficient when you control both ends. GraphQL complexity not justified.
+
+**Factories:**
+```
+factory_bot → Fixtures
+```
+Why: Fixtures are simpler, faster, and encourage thinking about data relationships upfront.
+</what_they_avoid>
+
+<decision_framework>
+## Decision Framework
+
+Before adding a gem, ask:
+
+1. **Can vanilla Rails do this?**
+   - ActiveRecord can do most things Sequel can
+   - ActionMailer handles email fine
+   - ActiveJob works for most job needs
+
+2. **Is the complexity worth it?**
+   - 150 lines of custom code vs. 10,000-line gem
+   - You'll understand your code better
+   - Fewer upgrade headaches
+
+3. **Does it add infrastructure?**
+   - Redis? Consider database-backed alternatives
+   - External service? Consider building in-house
+   - Simpler infrastructure = fewer failure modes
+
+4. **Is it from someone you trust?**
+   - 37signals gems: battle-tested at scale
+   - Well-maintained, focused gems: usually fine
+   - Kitchen-sink gems: probably overkill
+
+**The philosophy:**
+> "Build solutions before reaching for gems."
+
+Not anti-gem, but pro-understanding. Use gems when they genuinely solve a problem you have, not a problem you might have.
+</decision_framework>
+
+<gem_patterns>
+## Gem Usage Patterns
+
+**Pagination:**
+```ruby
+# geared_pagination - cursor-based
+class CardsController < ApplicationController
+  def index
+    @cards = @board.cards.geared(page: params[:page])
+  end
+end
+```
+
+**Markdown:**
+```ruby
+# redcarpet + rouge
+class MarkdownRenderer
+  def self.render(text)
+    Redcarpet::Markdown.new(
+      Redcarpet::Render::HTML.new(filter_html: true),
+      autolink: true,
+      fenced_code_blocks: true
+    ).render(text)
+  end
+end
+```
+
+**Background jobs:**
+```ruby
+# solid_queue - no Redis
+class ApplicationJob < ActiveJob::Base
+  queue_as :default
+  # Just works, backed by database
+end
+```
+
+**Caching:**
+```ruby
+# solid_cache - no Redis
+# config/environments/production.rb
+config.cache_store = :solid_cache_store
+```
+</gem_patterns>

plugins/compound-engineering/skills/dhh-rails-style/references/models.md

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+# Models - DHH Rails Style
+
+<model_concerns>
+## Concerns for Horizontal Behavior
+
+Models heavily use concerns. A typical Card model includes 14+ concerns:
+
+```ruby
+class Card < ApplicationRecord
+  include Assignable
+  include Attachments
+  include Broadcastable
+  include Closeable
+  include Colored
+  include Eventable
+  include Golden
+  include Mentions
+  include Multistep
+  include Pinnable
+  include Postponable
+  include Readable
+  include Searchable
+  include Taggable
+  include Watchable
+end
+```
+
+Each concern is self-contained with associations, scopes, and methods.
+
+**Naming:** Adjectives describing capability (`Closeable`, `Publishable`, `Watchable`)
+</model_concerns>
+
+<state_records>
+## State as Records, Not Booleans
+
+Instead of boolean columns, create separate records:
+
+```ruby
+# Instead of:
+closed: boolean
+is_golden: boolean
+postponed: boolean
+
+# Create records:
+class Card::Closure < ApplicationRecord
+  belongs_to :card
+  belongs_to :creator, class_name: "User"
+end
+
+class Card::Goldness < ApplicationRecord
+  belongs_to :card
+  belongs_to :creator, class_name: "User"
+end
+
+class Card::NotNow < ApplicationRecord
+  belongs_to :card
+  belongs_to :creator, class_name: "User"
+end
+```
+
+**Benefits:**
+- Automatic timestamps (when it happened)
+- Track who made changes
+- Easy filtering via joins and `where.missing`
+- Enables rich UI showing when/who
+
+**In the model:**
+```ruby
+module Closeable
+  extend ActiveSupport::Concern
+
+  included do
+    has_one :closure, dependent: :destroy
+  end
+
+  def closed?
+    closure.present?
+  end
+
+  def close(creator: Current.user)
+    create_closure!(creator: creator)
+  end
+
+  def reopen
+    closure&.destroy
+  end
+end
+```
+
+**Querying:**
+```ruby
+Card.joins(:closure)         # closed cards
+Card.where.missing(:closure) # open cards
+```
+</state_records>
+
+<callbacks>
+## Callbacks - Used Sparingly
+
+Only 38 callback occurrences across 30 files in Fizzy. Guidelines:
+
+**Use for:**
+- `after_commit` for async work
+- `before_save` for derived data
+- `after_create_commit` for side effects
+
+**Avoid:**
+- Complex callback chains
+- Business logic in callbacks
+- Synchronous external calls
+
+```ruby
+class Card < ApplicationRecord
+  after_create_commit :notify_watchers_later
+  before_save :update_search_index, if: :title_changed?
+
+  private
+    def notify_watchers_later
+      NotifyWatchersJob.perform_later(self)
+    end
+end
+```
+</callbacks>
+
+<scopes>
+## Scope Naming
+
+Standard scope names:
+
+```ruby
+class Card < ApplicationRecord
+  scope :chronologically, -> { order(created_at: :asc) }
+  scope :reverse_chronologically, -> { order(created_at: :desc) }
+  scope :alphabetically, -> { order(title: :asc) }
+  scope :latest, -> { reverse_chronologically.limit(10) }
+
+  # Standard eager loading
+  scope :preloaded, -> { includes(:creator, :assignees, :tags) }
+
+  # Parameterized
+  scope :indexed_by, ->(column) { order(column => :asc) }
+  scope :sorted_by, ->(column, direction = :asc) { order(column => direction) }
+end
+```
+</scopes>
+
+<poros>
+## Plain Old Ruby Objects
+
+POROs namespaced under parent models:
+
+```ruby
+# app/models/event/description.rb
+class Event::Description
+  def initialize(event)
+    @event = event
+  end
+
+  def to_s
+    # Presentation logic for event description
+  end
+end
+
+# app/models/card/eventable/system_commenter.rb
+class Card::Eventable::SystemCommenter
+  def initialize(card)
+    @card = card
+  end
+
+  def comment(message)
+    # Business logic
+  end
+end
+
+# app/models/user/filtering.rb
+class User::Filtering
+  # View context bundling
+end
+```
+
+**NOT used for service objects.** Business logic stays in models.
+</poros>
+
+<verbs_predicates>
+## Method Naming
+
+**Verbs** - Actions that change state:
+```ruby
+card.close
+card.reopen
+card.gild      # make golden
+card.ungild
+board.publish
+board.archive
+```
+
+**Predicates** - Queries derived from state:
+```ruby
+card.closed?    # closure.present?
+card.golden?    # goldness.present?
+board.published?
+```
+
+**Avoid** generic setters:
+```ruby
+# Bad
+card.set_closed(true)
+card.update_golden_status(false)
+
+# Good
+card.close
+card.ungild
+```
+</verbs_predicates>