Modern Rails 8 Architecture Patterns

Overview

Rails 8 follows "convention over configuration" with a layered architecture that separates concerns. This skill guides architectural decisions for clean, maintainable code.

Architecture Decision Tree

Where should this code go?
│
├─ Is it view/display formatting?
│   └─ → Presenter (see: rails-presenter skill)
│
├─ Is it complex business logic?
│   └─ → Service Object (see: rails-service-object skill)
│
├─ Is it a complex database query?
│   └─ → Query Object (see: rails-query-object skill)
│
├─ Is it shared behavior across models?
│   └─ → Concern (see: rails-concern skill)
│
├─ Is it authorization logic?
│   └─ → Policy (see: authorization-pundit skill)
│
├─ Is it reusable UI with logic?
│   └─ → ViewComponent (see: viewcomponent-patterns skill)
│
├─ Is it async/background work?
│   └─ → Job (see: solid-queue-setup skill)
│
├─ Is it a complex form (multi-model, wizard)?
│   └─ → Form Object (see: form-object-patterns skill)
│
├─ Is it a transactional email?
│   └─ → Mailer (see: action-mailer-patterns skill)
│
├─ Is it real-time/WebSocket communication?
│   └─ → Channel (see: action-cable-patterns skill)
│
├─ Is it data validation only?
│   └─ → Model (see: rails-model-generator skill)
│
└─ Is it HTTP request/response handling only?
    └─ → Controller (see: rails-controller skill)

Layer Interaction Flow

┌─────────────────────────────────────────────────────────────┐
│                        REQUEST                               │
└─────────────────────────┬───────────────────────────────────┘
                          ▼
┌─────────────────────────────────────────────────────────────┐
│                     CONTROLLER                               │
│  • Authenticate (Authentication concern)                     │
│  • Authorize (Policy)                                        │
│  • Parse params                                              │
│  • Delegate to Service/Query                                 │
└──────────┬─────────────────────────────────┬────────────────┘
           │                                 │
           ▼                                 ▼
┌─────────────────────┐           ┌─────────────────────┐
│      SERVICE        │           │       QUERY         │
│  • Business logic   │           │  • Complex queries  │
│  • Orchestration    │           │  • Aggregations     │
│  • Transactions     │           │  • Reports          │
└──────────┬──────────┘           └──────────┬──────────┘
           │                                 │
           ▼                                 ▼
┌─────────────────────────────────────────────────────────────┐
│                        MODEL                                 │
│  • Validations  • Associations  • Scopes  • Callbacks       │
└─────────────────────────┬───────────────────────────────────┘
                          │
           ┌──────────────┴──────────────┐
           ▼                             ▼
┌─────────────────────┐       ┌─────────────────────┐
│     PRESENTER       │       │    VIEW COMPONENT   │
│  • Formatting       │       │  • Reusable UI      │
│  • Display logic    │       │  • Encapsulated     │
└──────────┬──────────┘       └──────────┬──────────┘
           │                             │
           └──────────────┬──────────────┘
                          ▼
┌─────────────────────────────────────────────────────────────┐
│                       RESPONSE                               │
└─────────────────────────────────────────────────────────────┘

ASYNC FLOWS:
┌─────────────────────┐       ┌─────────────────────┐
│        JOB          │       │      CHANNEL        │
│  • Background work  │       │  • Real-time        │
│  • Solid Queue      │       │  • WebSockets       │
└─────────────────────┘       └─────────────────────┘

EMAIL FLOWS:
┌─────────────────────┐
│       MAILER        │
│  • Transactional    │
│  • Notifications    │
└─────────────────────┘

See layer-interactions.md for detailed examples.

Layer Responsibilities

Project Directory Structure

app/
├── channels/            # Action Cable channels
├── components/          # ViewComponents (UI +

...