Events - PraisonAI

Agents emit events you can listen to - track progress, log activity, and extend behavior.

This page covers the AgentEventBus — a publish/subscribe hook system for agent lifecycle (start, message, complete, error). For the per-turn structured event stream used to render tool calls and text deltas in real time, see Streaming Events.

Quick Start

Simple Usage

import { Agent } from 'praisonai';

const agent = new Agent({
  instructions: 'You are a helpful assistant'
});

agent.on('message', (event) => {
  console.log('Agent said:', event.content);
});

agent.on('tool_call', (event) => {
  console.log('Tool used:', event.name);
});

await agent.chat('Search for weather');

With Configuration

agent.on('*', (event) => {
  console.log(`[${event.type}]`, event.data);
});

User Interaction Flow

Configuration Levels

// Level 1: Method - Simple listener
agent.on('message', (e) => console.log(e));

// Level 2: Array - Multiple events
agent.on(['start', 'complete'], (e) => {
  console.log(`${e.type} at ${e.timestamp}`);
});

// Level 3: Instance - Event bus
import { AgentEventBus } from 'praisonai';

const bus = new AgentEventBus();

bus.subscribe('agent.*', (event) => {
  sendToAnalytics(event);
});

const agent = new Agent({ eventBus: bus });

Event Types

Event	When
`start`	Agent begins processing
`message`	Agent produces output
`tool_call`	Agent calls a tool
`error`	Something goes wrong
`complete`	Agent finishes

API Reference

Events Module

Complete events module

AgentEventBus

Event bus class

Best Practices

Log important events

Track tool calls and errors for debugging.

Use wildcards sparingly

Subscribe to specific events for better performance.

Handle errors

Always listen for ‘error’ events in production.

Hooks

Lifecycle hooks

PubSub

Publish-subscribe

​Quick Start

​User Interaction Flow

​Configuration Levels

​Event Types

​API Reference

Events Module

AgentEventBus

​Best Practices

​Related

Hooks

PubSub

Quick Start

User Interaction Flow

Configuration Levels

Event Types

API Reference

Best Practices

Related