rails

Activate When

• /godmode:rails, "rails app", "ruby on rails"
• "activerecord", "hotwire", "turbo", "sidekiq"
• Rails backend implementation tasks

Workflow

1. Project Assessment

Rails version: <7.2.x or 8.0.x>
Ruby version: <3.3.x>
Architecture: Full-stack (Hotwire)|API-only|Hybrid
Database: PostgreSQL (ALWAYS for production)
Jobs: Sidekiq|Solid Queue|Good Job
Real-time: Action Cable|Turbo Streams|None
Auth: Devise|has_secure_password|Rails 8 built-in
Assets: Propshaft + Import Maps|esbuild|Vite

cat Gemfile | grep -E "rails|ruby"
cat config/database.yml | grep adapter

IF Rails 8: prefer built-in generators (auth, jobs). IF < heavy JS: Import Maps (no build step). IF heavy JS: esbuild or Vite.

2. Rails Conventions

| Convention | Rule |
| Model | Singular CamelCase (Order) |
| Table | Plural snake_case (orders) |
| Controller | Plural CamelCase (OrdersController) |
| File | snake_case (order.rb) |
| Foreign key | <model>_id (customer_id) |
| Join table | Alphabetical (labels_orders) |
| Timestamps | created_at, updated_at (auto) |

NEVER violate naming conventions (framework superpower). Extract to services when model > 200 LOC.

3. ActiveRecord Patterns

| Pattern | When |
| includes(:assoc) | Default N+1 prevention |
| preload(:assoc) | Separate queries (large joins) |
| eager_load(:assoc) | Need WHERE on association |
| select(:col1,:col2) | Reduce data transfer |
| find_each(batch:1000) | Process large datasets |
| counter_cache: true | Avoid COUNT queries |

ALWAYS use includes for associations in views. ALWAYS enable strict_loading in development. NEVER .all.each for large datasets — use find_each. IF foreign key exists: MUST have database index.

4. Hotwire (Turbo + Stimulus)

| Need | Use |
| SPA-like navigation | Turbo Drive (automatic) |
| Update one section | Turbo Frames |
| Real-time broadcast | Turbo Streams |
| Toggle/dropdown/count | Stimulus controller |
| Full SPA (React/Vue) | Rails API-only + SPA |

IF < 90% of interactivity: Hotwire handles it. IF complex client state: Rails API + React/Vue.