# Broadcasting: Faye → ActionCable Migration Guide

## Current state

```
Model (SimplyStored::Couch)
  → ApplicationController.new.broadcast_user   # ⚠️ anti-pattern
    → Mozo.broadcast_user
      → Mozo::Broadcaster::Faye.new.broadcast  # HTTP POST to Faye
        → Faye server (Thin, port 9296)
          → WebSocket → browser clients
```

## Target state

```
Model (Broadcastable concern)
  → Mozo.broadcast_user
    → Mozo::Broadcaster::ActionCable.new.broadcast  # in-process async
      → ActionCable (Rails built-in)
        → WebSocket → browser clients
```

## What this branch adds

| File | Purpose |
|------|---------|
| `lib/mozo/broadcaster/action_cable.rb` | Drop-in ActionCable broadcaster adapter |
| `config/cable.yml` | ActionCable configuration (async for single-server) |
| `app/channels/application_cable/connection.rb` | WebSocket auth via auth_token |
| `app/channels/mozo_channel.rb` | Channel authorization for user/supplier/employee |
| `app/models/concerns/broadcastable.rb` | Clean module for models (replaces old monkey-patch) |
| `config/routes.rb` | Mounts `/cable` WebSocket endpoint |
| `config/initializers/model_broadcast.rb` | Fixed: delegates to Mozo directly (no more `ApplicationController.new`) |

## How to switch

### 1. Server (one-line change)

In `config/initializers/mozo_settings.rb`, change:

```ruby
# Mozo.broadcaster = Mozo::Broadcaster::Faye.new  # old
Mozo.broadcaster = Mozo::Broadcaster::ActionCable.new  # new
```

### 2. Client (mozo-user / mozo-supplier)

**Old Faye client (conceptual):**
```js
var client = new Faye.Client('https://events.mozo.bar/faye');
client.subscribe('/user/123', function(msg) { ... });
```

**New ActionCable client:**
```js
// Using @rails/actioncable npm package
import { createConsumer } from "@rails/actioncable";

const consumer = createConsumer(
  `wss://mozo.bar/cable?auth_token=${authToken}`
);

consumer.subscriptions.create(
  { channel: "MozoChannel", id: "user_123" },
  {
    received(data) {
      // data = { event: "list_closed", data: { id: 42 } }
      handleEvent(data.event, data.data);
    }
  }
);
```

### 3. Remove Faye

Once stable:
- Remove `gem 'faye'` from Gemfile
- Remove `faye/` directory
- Remove nginx `events.mozo.bar` vhost
- Stop the Faye Thin process

## Benefits

- **No extra process** — ActionCable runs inside Puma
- **Async** — `broadcast` is non-blocking
- **Simpler deploys** — one less service to manage
- **WebSocket native** — no long-polling fallback complexity
- **Rails auth** — cookies/sessions work automatically