Complete Developer Guide - ElizaOS Documentation

Overview

The @elizaos/plugin-bootstrap package is the core message handler for ElizaOS agents. It provides the fundamental event handlers, actions, providers, evaluators, and services that enable agents to process messages from any communication platform (Discord, Telegram, message bus server, etc.) and generate intelligent responses.

This plugin is essential for any ElizaOS agent as it contains the core logic for:

Processing incoming messages
Determining whether to respond
Generating contextual responses
Managing agent actions
Evaluating interactions
Maintaining conversation state

Architecture Overview

Message Processing Flow

1. Message Reception

When a message arrives from any platform (Discord, Telegram, etc.), it triggers the MESSAGE_RECEIVED event, which is handled by the messageReceivedHandler.

2. Initial Processing

const messageReceivedHandler = async ({
  runtime,
  message,
  callback,
  onComplete,
}: MessageReceivedHandlerParams): Promise<void> => {
  // 1. Generate unique response ID
  const responseId = v4();

  // 2. Track run lifecycle
  const runId = runtime.startRun();

  // 3. Save message to memory
  await Promise.all([
    runtime.addEmbeddingToMemory(message),
    runtime.createMemory(message, 'messages'),
  ]);

  // 4. Process attachments (images, documents)
  if (message.content.attachments) {
    message.content.attachments = await processAttachments(message.content.attachments, runtime);
  }

  // 5. Determine if agent should respond
  // 6. Generate response if needed
  // 7. Process actions
  // 8. Run evaluators
};

3. Should Respond Logic

The agent determines whether to respond based on:

Room type (DMs always get responses)
Agent state (muted/unmuted)
Message content analysis
Character configuration

4. Response Generation

If the agent decides to respond:

Compose state with relevant providers
Generate response using LLM
Parse XML response format
Execute actions
Send response via callback

Core Components

Event Handlers

Event handlers process different types of events in the system:

Event Type	Handler	Description
`MESSAGE_RECEIVED`	`messageReceivedHandler`	Main message processing handler
`VOICE_MESSAGE_RECEIVED`	`messageReceivedHandler`	Handles voice messages
`REACTION_RECEIVED`	`reactionReceivedHandler`	Stores reactions in memory
`MESSAGE_DELETED`	`messageDeletedHandler`	Removes deleted messages from memory
`CHANNEL_CLEARED`	`channelClearedHandler`	Clears all messages from a channel
`POST_GENERATED`	`postGeneratedHandler`	Creates social media posts
`WORLD_JOINED`	`handleServerSync`	Syncs server/world data
`ENTITY_JOINED`	`syncSingleUser`	Syncs individual user data

Actions

Actions define what an agent can do in response to messages:

Core Actions

REPLY (reply.ts)
- Default response action
- Generates contextual text responses
- Can be used alone or chained with other actions
IGNORE (ignore.ts)
- Explicitly ignores a message
- Saves the ignore decision to memory
- Used when agent decides not to respond
NONE (none.ts)
- No-op action
- Used as placeholder or default

Room Management Actions

FOLLOW_ROOM (followRoom.ts)
- Subscribes agent to room updates
- Enables notifications for room activity
UNFOLLOW_ROOM (unfollowRoom.ts)
- Unsubscribes from room updates
- Stops notifications
MUTE_ROOM (muteRoom.ts)
- Temporarily disables responses in a room
- Agent still processes messages but doesn’t respond
UNMUTE_ROOM (unmuteRoom.ts)
- Re-enables responses in a muted room

Advanced Actions

SEND_MESSAGE (sendMessage.ts)
- Sends messages to specific rooms
- Can target different channels
UPDATE_ENTITY (updateEntity.ts)
- Updates entity information in the database
- Modifies user profiles, metadata
CHOICE (choice.ts)
- Presents multiple choice options
- Used for interactive decision making
UPDATE_ROLE (roles.ts)
- Manages user roles and permissions
- Updates access levels
UPDATE_SETTINGS (settings.ts)
- Modifies agent or room settings
- Configures behavior parameters
GENERATE_IMAGE (imageGeneration.ts)
- Creates images using AI models
- Attaches generated images to responses

Providers

Providers supply contextual information to the agent during response generation:

Core Providers

RECENT_MESSAGES (recentMessages.ts)

// Provides conversation history and context
{
  recentMessages: Memory[],
  recentInteractions: Memory[],
  formattedConversation: string
}

TIME (time.ts)
- Current date and time
- Timezone information
- Temporal context
CHARACTER (character.ts)
- Agent’s personality traits
- Background information
- Behavioral guidelines
ENTITIES (entities.ts)
- Information about users in the room
- Entity relationships
- User metadata
RELATIONSHIPS (relationships.ts)
- Social graph data
- Interaction history
- Relationship tags
WORLD (world.ts)
- Environment context
- Server/world information
- Room details
ANXIETY (anxiety.ts)
- Agent’s emotional state
- Stress levels
- Mood indicators
ATTACHMENTS (attachments.ts)
- Media content analysis
- Image descriptions
- Document summaries
CAPABILITIES (capabilities.ts)
- Available actions
- Service capabilities
- Feature flags
FACTS (facts.ts)
- Stored knowledge
- Learned information
- Contextual facts

Evaluators

Evaluators perform post-interaction cognitive processing:

REFLECTION Evaluator (`reflection.ts`)

The reflection evaluator:

Analyzes conversation quality
Extracts new facts
Identifies relationships
Updates knowledge base

{
  "thought": "Self-reflective analysis of interaction",
  "facts": [
    {
      "claim": "Factual statement learned",
      "type": "fact|opinion|status",
      "in_bio": false,
      "already_known": false
    }
  ],
  "relationships": [
    {
      "sourceEntityId": "initiator_id",
      "targetEntityId": "target_id",
      "tags": ["interaction_type", "context"]
    }
  ]
}

Services

TaskService (`task.ts`)

Manages scheduled and background tasks:

class TaskService extends Service {
  // Executes tasks based on:
  // - Schedule (repeating tasks)
  // - Queue (one-time tasks)
  // - Validation rules
  // - Worker availability
}

Task features:

Repeating tasks: Execute at intervals
One-time tasks: Execute once and delete
Immediate tasks: Execute on creation
Validated tasks: Conditional execution

Detailed Component Documentation

Message Handler Deep Dive

1. Attachment Processing

export async function processAttachments(
  attachments: Media[],
  runtime: IAgentRuntime
): Promise<Media[]> {
  // For images: Generate descriptions using vision models
  // For documents: Extract text content
  // For other media: Process as configured
}

2. Should Bypass Logic

export function shouldBypassShouldRespond(
  runtime: IAgentRuntime,
  room?: Room,
  source?: string
): boolean {
  // DMs always bypass shouldRespond check
  // Voice DMs bypass
  // API calls bypass
  // Configurable via SHOULD_RESPOND_BYPASS_TYPES
}

3. Response ID Management

// Prevents duplicate responses when multiple messages arrive quickly
const latestResponseIds = new Map<string, Map<string, string>>();
// Only process if this is still the latest response for the room

Action Handler Pattern

All actions follow this structure:

export const actionName = {
  name: 'ACTION_NAME',
  similes: ['ALTERNATIVE_NAME', 'SYNONYM'],
  description: 'What this action does',
  validate: async (runtime: IAgentRuntime) => boolean,
  handler: async (
    runtime: IAgentRuntime,
    message: Memory,
    state: State,
    options: any,
    callback: HandlerCallback,
    responses?: Memory[]
  ) => boolean,
  examples: ActionExample[][]
}

Provider Pattern

Providers follow this structure:

export const providerName: Provider = {
  name: 'PROVIDER_NAME',
  description: 'What context this provides',
  position: 100, // Order priority
  get: async (runtime: IAgentRuntime, message: Memory) => {
    return {
      data: {}, // Raw data
      values: {}, // Processed values
      text: '', // Formatted text for prompt
    };
  },
};

Configuration

Environment Variables

# Control which room types bypass shouldRespond check
SHOULD_RESPOND_BYPASS_TYPES=["dm", "voice_dm", "api"]

# Control which sources bypass shouldRespond check
SHOULD_RESPOND_BYPASS_SOURCES=["client_chat", "api"]

# Conversation context length
CONVERSATION_LENGTH=20

# Response timeout (ms)
RESPONSE_TIMEOUT=3600000  # 1 hour

Character Templates

Configure custom templates:

character: {
  templates: {
    messageHandlerTemplate: string,
    shouldRespondTemplate: string,
    reflectionTemplate: string,
    postCreationTemplate: string
  }
}

Template Customization

Understanding Templates

Templates are the core prompts that control how your agent thinks and responds. The plugin-bootstrap provides default templates, but you can customize them through your character configuration to create unique agent behaviors.

Available Templates

shouldRespondTemplate - Controls when the agent decides to respond
messageHandlerTemplate - Governs how the agent generates responses and selects actions
reflectionTemplate - Manages post-interaction analysis
postCreationTemplate - Handles social media post generation

How Templates Work

Templates use a mustache-style syntax with placeholders:

{{agentName}} - The agent’s name
{{providers}} - Injected provider context
{{actionNames}} - Available actions
{{recentMessages}} - Conversation history

Customizing Templates

You can override any template in your character configuration:

import { Character } from '@elizaos/core';

export const myCharacter: Character = {
  name: 'TechBot',
  // ... other config ...

  templates: {
    // Custom shouldRespond logic
    shouldRespondTemplate: `<task>Decide if {{agentName}} should help with technical questions.</task>

{{providers}}

<rules>
- Always respond to technical questions
- Always respond to direct mentions
- Ignore casual chat unless it's tech-related
- If someone asks for help, ALWAYS respond
</rules>

<output>
<response>
  <reasoning>Your technical assessment</reasoning>
  <action>RESPOND | IGNORE | STOP</action>
</response>
</output>`,

    // Custom message handler with specific behavior
    messageHandlerTemplate: `<task>Generate a helpful technical response as {{agentName}}.</task>

{{providers}}

Available actions: {{actionNames}}

<personality>
- Be precise and technical but friendly
- Provide code examples when relevant
- Ask clarifying questions for vague requests
- Suggest best practices
</personality>

<output>
<response>
  <thought>Technical analysis of the request</thought>
  <actions>ACTION1,ACTION2</actions>
  <providers>PROVIDER1,PROVIDER2</providers>
  <text>Your helpful technical response</text>
</response>
</output>`,

    // Custom reflection template
    reflectionTemplate: `<task>Analyze the technical conversation for learning opportunities.</task>

{{recentMessages}}

<focus>
- Extract technical facts and solutions
- Note programming patterns discussed
- Track user expertise levels
- Identify knowledge gaps
</focus>

<output>
{
  "thought": "Technical insight gained",
  "facts": [
    {
      "claim": "Technical fact learned",
      "type": "technical|solution|pattern",
      "topic": "programming|devops|architecture"
    }
  ],
  "userExpertise": {
    "level": "beginner|intermediate|expert",
    "topics": ["topic1", "topic2"]
  }
}
</output>`,
  },
};

Template Processing Flow

Template Selection: The system selects the appropriate template based on the current operation
Variable Injection: Placeholders are replaced with actual values
Provider Integration: Provider data is formatted and injected
LLM Processing: The completed prompt is sent to the language model
Response Parsing: The XML/JSON response is parsed and validated

Advanced Template Techniques

Conditional Logic

messageHandlerTemplate: `{{providers}}

<conditions>
{{#if isNewUser}}
Provide extra guidance and explanations
{{/if}}

{{#if hasAttachments}}
Analyze the attached media carefully
{{/if}}
</conditions>

<response>
  <thought>Context-aware thinking</thought>
  <actions>REPLY</actions>
  <text>Adaptive response</text>
</response>`;

Custom Provider Integration

messageHandlerTemplate: `<context>
{{providers.CUSTOM_CONTEXT}}
{{providers.USER_HISTORY}}
</context>

Generate response considering the custom context above...`;

Understanding the Callback Mechanism

What is the Callback?

The callback is a function passed to every action handler that sends the response back to the user. When you call the callback, you’re telling the system “here’s what to send back”.

Callback Flow

// In an action handler
async handler(runtime, message, state, options, callback) {
  // 1. Process the request
  const result = await doSomething();

  // 2. Call callback to send response
  await callback({
    text: "Here's your response",      // The message to send
    actions: ['ACTION_NAME'],          // Actions taken
    thought: 'Internal reasoning',     // Agent's thought process
    attachments: [],                   // Optional media
    metadata: {}                       // Optional metadata
  });

  // 3. Return success
  return true;
}

Important Callback Concepts

Calling callback = Sending a message: When you invoke callback(), the message is sent to the user
Multiple callbacks = Multiple messages: You can call callback multiple times to send multiple messages
No callback = No response: If you don’t call callback, no message is sent
Async operation: Always await the callback for proper error handling

Callback Examples

Simple Response

await callback({
  text: 'Hello! How can I help?',
  actions: ['REPLY'],
});

Response with Attachments

await callback({
  text: "Here's the image you requested",
  actions: ['GENERATE_IMAGE'],
  attachments: [
    {
      url: 'https://example.com/image.png',
      contentType: 'image/png',
    },
  ],
});

Multi-Message Response

// First message
await callback({
  text: 'Let me check that for you...',
  actions: ['ACKNOWLEDGE'],
});

// Do some processing
const result = await fetchData();

// Second message with results
await callback({
  text: `Here's what I found: ${result}`,
  actions: ['REPLY'],
});

Conditional Response

if (error) {
  await callback({
    text: 'Sorry, I encountered an error',
    actions: ['ERROR'],
    metadata: { error: error.message },
  });
} else {
  await callback({
    text: 'Successfully completed!',
    actions: ['SUCCESS'],
  });
}

Callback Best Practices

Always call callback: Even for errors, call callback to inform the user
Be descriptive: Include clear text explaining what happened
Use appropriate actions: Tag responses with the correct action names
Include thought: Help with debugging by including agent reasoning
Handle errors gracefully: Provide user-friendly error messages

Integration Guide

1. Basic Integration

import { Project, ProjectAgent, Character } from '@elizaos/core';

// Define your character with bootstrap plugin
const character: Character = {
  name: 'MyAgent',
  bio: ['An intelligent agent powered by ElizaOS'],
  plugins: [
    '@elizaos/plugin-sql',
    '@elizaos/plugin-bootstrap',
  ],
};

// Create the agent
const agent: ProjectAgent = {
  character,
  // Custom plugins go here at agent level
  plugins: [],
};

// Export the project
export const project = {
  agents: [agent]
};

2. Custom Event Handlers

// Add custom handling for existing events
runtime.on(EventType.MESSAGE_RECEIVED, async (payload) => {
  // Custom pre-processing
  await customPreProcessor(payload);

  // Call default handler
  await bootstrapPlugin.events[EventType.MESSAGE_RECEIVED][0](payload);

  // Custom post-processing
  await customPostProcessor(payload);
});

3. Extending Actions

// Create custom action that extends REPLY
const customReplyAction = {
  ...replyAction,
  name: 'CUSTOM_REPLY',
  handler: async (...args) => {
    // Custom logic
    await customLogic();

    // Call original handler
    return replyAction.handler(...args);
  },
};

Examples

Example 1: Basic Message Flow

// 1. Message arrives
const message = {
  id: 'msg-123',
  entityId: 'user-456',
  roomId: 'room-789',
  content: {
    text: 'Hello, how are you?',
  },
};

// 2. Bootstrap processes it
// - Saves to memory
// - Checks shouldRespond
// - Generates response
// - Executes REPLY action
// - Runs reflection evaluator

// 3. Response sent via callback
callback({
  text: "I'm doing well, thank you! How can I help you today?",
  actions: ['REPLY'],
  thought: 'User greeted me politely, responding in kind',
});

Example 2: Multi-Action Response

// Complex response with multiple actions
const response = {
  thought: 'User needs help with a technical issue in a specific room',
  text: "I'll help you with that issue.",
  actions: ['REPLY', 'FOLLOW_ROOM', 'UPDATE_SETTINGS'],
  providers: ['TECHNICAL_DOCS', 'ROOM_INFO'],
};

Example 3: Task Scheduling

// Register a task worker
runtime.registerTaskWorker({
  name: 'DAILY_SUMMARY',
  validate: async (runtime) => {
    const hour = new Date().getHours();
    return hour === 9; // Run at 9 AM
  },
  execute: async (runtime, options) => {
    // Generate and post daily summary
    await runtime.emitEvent(EventType.POST_GENERATED, {
      runtime,
      worldId: options.worldId,
      // ... other params
    });
  },
});

// Create the task
await runtime.createTask({
  name: 'DAILY_SUMMARY',
  metadata: {
    updateInterval: 1000 * 60 * 60, // Check hourly
  },
  tags: ['queue', 'repeat'],
});

Best Practices

Always check message validity before processing
Use providers to gather context instead of direct database queries
Chain actions for complex behaviors
Implement proper error handling in custom components
Respect rate limits and response timeouts
Test with different room types and message formats
Monitor reflection outputs for agent learning

Troubleshooting

Common Issues

Agent not responding
- Check room type and bypass settings
- Verify agent isn’t muted
- Check shouldRespond logic
Duplicate responses
- Ensure response ID tracking is working
- Check for multiple handler registrations
Missing context
- Verify providers are registered
- Check state composition
Action failures
- Validate action requirements
- Check handler errors
- Verify callback execution

Summary

The @elizaos/plugin-bootstrap package is the heart of ElizaOS’s message processing system. It provides a complete framework for:

Receiving and processing messages from any platform
Making intelligent response decisions
Generating contextual responses
Executing complex action chains
Learning from interactions
Managing background tasks

Understanding this plugin is essential for developing effective ElizaOS agents and extending the platform’s capabilities.

Message Processing Core Message Processing Flow

On this page

Overview
Architecture Overview
Message Processing Flow
1. Message Reception
2. Initial Processing
3. Should Respond Logic
4. Response Generation
Core Components
Event Handlers
Actions
Core Actions
Room Management Actions
Advanced Actions
Providers
Core Providers
Evaluators
REFLECTION Evaluator (reflection.ts)
Services
TaskService (task.ts)
Detailed Component Documentation
Message Handler Deep Dive
1. Attachment Processing
2. Should Bypass Logic
3. Response ID Management
Action Handler Pattern
Provider Pattern
Configuration
Environment Variables
Character Templates
Template Customization
Understanding Templates
Available Templates
How Templates Work
Customizing Templates
Template Processing Flow
Advanced Template Techniques
Conditional Logic
Custom Provider Integration
Understanding the Callback Mechanism
What is the Callback?
Callback Flow
Important Callback Concepts
Callback Examples
Simple Response
Response with Attachments
Multi-Message Response
Conditional Response
Callback Best Practices
Integration Guide
1. Basic Integration
2. Custom Event Handlers
3. Extending Actions
Examples
Example 1: Basic Message Flow
Example 2: Multi-Action Response
Example 3: Task Scheduling
Best Practices
Troubleshooting
Common Issues
Summary

Getting Started

Core Plugins

LLM Providers

Platform Integrations

​Overview

​Architecture Overview

​Message Processing Flow

​1. Message Reception

​2. Initial Processing

​3. Should Respond Logic

​4. Response Generation

​Core Components

​Event Handlers

​Actions

​Core Actions

​Room Management Actions

​Advanced Actions

​Providers

​Core Providers

​Evaluators

​REFLECTION Evaluator (reflection.ts)

​Services

​TaskService (task.ts)

​Detailed Component Documentation

​Message Handler Deep Dive

​1. Attachment Processing

​2. Should Bypass Logic

​3. Response ID Management

​Action Handler Pattern

​Provider Pattern

​Configuration

​Environment Variables

​Character Templates

​Template Customization

​Understanding Templates

​Available Templates

​How Templates Work

​Customizing Templates

​Template Processing Flow

​Advanced Template Techniques

​Conditional Logic

​Custom Provider Integration

​Understanding the Callback Mechanism

​What is the Callback?

​Callback Flow

​Important Callback Concepts

​Callback Examples

​Simple Response

​Response with Attachments

​Multi-Message Response

​Conditional Response

​Callback Best Practices

​Integration Guide

​1. Basic Integration

​2. Custom Event Handlers

​3. Extending Actions

​Examples

​Example 1: Basic Message Flow

​Example 2: Multi-Action Response

​Example 3: Task Scheduling

​Best Practices

​Troubleshooting

​Common Issues

​Summary