When using AMQP over WebSockets with a TCP relay, connection loss was not properly detected, leaving connections, channels, and consumers in an inconsistent "not closed" state. This made it impossible for applications to detect when the underlying WebSocket connection was lost and implement proper reconnection logic.

Problem

The issue occurred when the WebSocket TCP relay process stopped or network connectivity was interrupted. While the WebSocket connection would close, the AMQP connection, channels, and consumers would remain in an "open" state, making it appear as if they were still functional when they were actually disconnected.

const amqp = new AMQPWebSocketClient('ws://localhost:15670/ws/amqp')
const conn = await amqp.connect()
const ch = await conn.channel()
const consumer = await queue.subscribe({}, handleMessage)

// TCP relay stops here...
console.log(conn.closed)     // false (incorrect!)
console.log(ch.closed)       // false (incorrect!)
// consumer.wait() never rejects

Solution

Enhanced the AMQPWebSocketClient to properly handle WebSocket connection loss by:

1. Proper Channel Cleanup: When WebSocket close or error events occur, all active channels are now properly closed with error information
2. State Consistency: Connection, channel, and consumer closed states are correctly updated
3. Error Propagation: Errors are propagated through the entire hierarchy (connection → channels → consumers)
4. Consumer Notification: Consumer wait() promises now properly reject when connection is lost

Usage

Applications can now detect connection loss in multiple ways:

// Connection-level monitoring
amqp.onerror = (error) => {
  console.log('Connection lost:', error.message)
  // Implement reconnection logic
}

// State checking
if (amqp.closed || channel.closed) {
  // Connection/channel is closed, need to reconnect
}

// Consumer monitoring
consumer.wait().catch(err => {
  console.log('Consumer lost connection:', err.message)
})

The fix ensures that when a WebSocket connection is lost:

• connection.closed becomes true
• All channels are marked as closed (channel.closed becomes true)
• All consumers are notified and their wait() promises reject
• Error callbacks are triggered at all levels
• Subsequent operations on closed objects throw appropriate errors

Fixes #111.

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