Chat - Streaming lifecycle

Observe the full runtime lifecycle for send, stream, stop, error, retry, and callbacks.

This demo brings the runtime lifecycle together in one place. It intentionally exposes success, failure, and long-running stream modes so you can observe every lifecycle phase:

sendMessage() — send a user turn and start streaming
stopStreaming() — cancel an active stream
retry() — retry a failed or cancelled message
onData — fires when a data-* chunk arrives
onFinish — fires when the stream ends (success, abort, or error)
onError — fires on any runtime error

Key concepts

The send-stream flow

When sendMessage() is called:

The user message is added optimistically with status: 'sending'
The adapter's sendMessage() returns a ReadableStream
Chunks update the assistant message in real time
A finish chunk completes the turn — user message moves to status: 'sent'

Stopping a stream

Call stopStreaming() to abort the active stream. The user message moves to status: 'cancelled' and the onFinish callback fires with isAbort: true.

Retrying a failed message

When a stream fails or is cancelled, call retry(messageId) with the user message ID. The runtime removes the failed assistant messages and resends the user turn.

Runtime callbacks

Register callbacks on ChatProvider to observe lifecycle events:

<ChatProvider
  adapter={adapter}
  onData={(part) => console.log('data chunk', part.type)}
  onFinish={(payload) => console.log('finished', payload.finishReason)}
  onError={(error) => console.log('error', error.message)}
>
  <MyChat />
</ChatProvider>

Key takeaways

The runtime manages the full send → stream → finish lifecycle automatically
stopStreaming() aborts the stream and triggers onFinish with isAbort: true
retry() removes failed assistant messages and resends the original user turn
Callbacks (onData, onFinish, onError) provide lifecycle observability without modifying the store

API

ChatRoot