> ## Documentation Index
> Fetch the complete documentation index at: https://praison.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Events
> React to agent lifecycle events
Agents emit events you can listen to - track progress, log activity, and extend behavior.
```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
graph LR
subgraph "Event System"
A[🤖 Agent] --> B[📡 Events]
B --> C[📝 Logger]
B --> D[📊 Analytics]
B --> E[🔔 Alerts]
end
classDef agent fill:#8B0000,stroke:#7C90A0,color:#fff
classDef tool fill:#189AB4,stroke:#7C90A0,color:#fff
class A agent
class B,C,D,E tool
classDef agent fill:#8B0000,color:#fff
classDef tool fill:#189AB4,color:#fff
```
## Quick Start
```typescript theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
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');
```
```typescript theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
agent.on('*', (event) => {
console.log(`[${event.type}]`, event.data);
});
```
***
## User Interaction Flow
```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
sequenceDiagram
participant User
participant Agent
participant Handler as Event Handler
User->>Agent: "Search for weather"
Agent->>Handler: emit('start')
Agent->>Handler: emit('tool_call', search)
Agent->>Handler: emit('message', response)
Agent->>Handler: emit('complete')
Agent-->>User: "The weather is..."
```
***
## Configuration Levels
```typescript theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
// Level 1: Method - Simple listener
agent.on('message', (e) => console.log(e));
// Level 2: Array - Multiple events
agent.on(['start', 'complete'], (e) => {
console.log(`${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
Complete events module
Event bus class
***
## Best Practices
Track tool calls and errors for debugging.
Subscribe to specific events for better performance.
Always listen for 'error' events in production.
***
## Related
Lifecycle hooks
Publish-subscribe