Session Events

session.subscribe() currently emits these core event types:

• turn-start
• text-delta
• reasoning-delta
• tool-call
• tool-result
• assistant-step
• turn-finish
• error

The most common one is text-delta

If you only need real-time text output, this is usually enough to handle first:

if (event.type === "text-delta") {
  process.stdout.write(event.text);
}

If you want a fuller experience, you will usually also handle:

• turn-start
• turn-finish
• error
• assistant-step
• tool-call
• tool-result

assistant-step is especially useful for transports such as chat bridges that want step-level visible reply chunks without owning Session history persistence themselves.