Middleware - PraisonAI

Agents can use middleware to process requests and responses - for logging, validation, or transformation.

Quick Start

Simple Usage

import { Agent, Middleware } from 'praisonai';

const logger: Middleware = async (ctx, next) => {
  console.log('Input:', ctx.input);
  await next();
  console.log('Output:', ctx.output);
};

const agent = new Agent({
  instructions: 'You are helpful',
  middleware: [logger]
});

With Configuration

const validate: Middleware = async (ctx, next) => {
  if (ctx.input.length > 1000) {
    throw new Error('Input too long');
  }
  await next();
};

User Interaction Flow

Configuration Levels

// Level 1: Array - Middleware list
const agent = new Agent({
  middleware: [logger, validator]
});

// Level 2: Function - Simple middleware
const agent = new Agent({
  middleware: [
    async (ctx, next) => {
      console.log(ctx.input);
      await next();
    }
  ]
});

// Level 3: Instance - Full control
const agent = new Agent({
  middleware: [
    {
      name: 'logger',
      handler: loggerFn,
      order: 1
    },
    {
      name: 'cache',
      handler: cacheFn,
      order: 2
    }
  ]
});

Common Uses

Use Case	Description
Logging	Track all requests/responses
Validation	Check inputs before processing
Transformation	Modify data in transit
Caching	Cache frequent responses

API Reference

HooksConfig

Hooks configuration (middleware pattern)

Best Practices

Keep middleware focused

Each middleware should do one thing well.

Order matters

Middleware runs in order - put validation first.

Always call next()

Forgetting next() breaks the chain.

Hooks

Lifecycle hooks

Guardrails

Input validation

​Quick Start

​User Interaction Flow

​Configuration Levels

​Common Uses

​API Reference