Plugin Developer Guide - ElizaOS Documentation

This comprehensive guide covers all aspects of plugin development in the ElizaOS system, consolidating patterns and best practices from platform plugins, LLM plugins, and DeFi plugins.

This guide uses bun as the package manager, which is the preferred tool for ElizaOS development. Bun provides faster installation times and built-in TypeScript support.

Introduction
Quick Start: Scaffolding Plugins with CLI
Plugin Architecture Overview
Core Plugin Components
Advanced: Creating Plugins Manually
Plugin Types and Patterns
Advanced Configuration
Testing Strategies
Security Best Practices
Publishing and Distribution
Reference Examples

Introduction

ElizaOS plugins are modular extensions that enhance AI agents with new capabilities, integrations, and behaviors. The plugin system follows a consistent architecture that enables:

Modularity: Add or remove functionality without modifying core code
Reusability: Share plugins across different agents
Type Safety: Full TypeScript support for robust development
Flexibility: Support for various plugin types (platform, LLM, DeFi, etc.)

What Can Plugins Do?

Platform Integrations: Connect to Discord, Telegram, Slack, Twitter, etc.
LLM Providers: Integrate different AI models (OpenAI, Anthropic, Google, etc.)
Blockchain/DeFi: Execute transactions, manage wallets, interact with smart contracts
Data Sources: Connect to databases, APIs, or external services
Custom Actions: Define new agent behaviors and capabilities

Quick Start: Scaffolding Plugins with CLI

The easiest way to create a new plugin is using the ElizaOS CLI, which provides interactive scaffolding with pre-configured templates. This is the recommended approach for most developers.

Using `elizaos create`

The CLI offers two plugin templates to get you started quickly:

# Interactive plugin creation
elizaos create

# Or specify the name directly
elizaos create my-plugin --type plugin

When creating a plugin, you’ll be prompted to choose between:

Quick Plugin (Backend Only) - Simple backend-only plugin without frontend
- Perfect for: API integrations, blockchain actions, data providers
- Includes: Basic plugin structure, actions, providers, services
- No frontend components or UI routes
Full Plugin (with Frontend) - Complete plugin with React frontend and API routes
- Perfect for: Plugins that need web UI, dashboards, or visual components
- Includes: Everything from Quick Plugin + React frontend, Vite setup, API routes
- Tailwind CSS pre-configured for styling

Quick Plugin Structure

After running elizaos create and selecting “Quick Plugin”, you’ll get:

plugin-my-plugin/
├── src/
│   ├── index.ts           # Plugin manifest
│   ├── actions/           # Your agent actions
│   │   └── example.ts
│   ├── providers/         # Context providers
│   │   └── example.ts
│   └── types/             # TypeScript types
│       └── index.ts
├── package.json           # Pre-configured with elizaos deps
├── tsconfig.json          # TypeScript config
├── tsup.config.ts         # Build configuration
└── README.md              # Plugin documentation

Full Plugin Structure

Selecting “Full Plugin” adds frontend capabilities:

plugin-my-plugin/
├── src/
│   ├── index.ts           # Plugin manifest with routes
│   ├── actions/
│   ├── providers/
│   ├── types/
│   └── frontend/          # React frontend
│       ├── App.tsx
│       ├── main.tsx
│       └── components/
├── public/                # Static assets
├── index.html             # Frontend entry
├── vite.config.ts         # Vite configuration
├── tailwind.config.js     # Tailwind setup
└── [other config files]

After Scaffolding

Once your plugin is created:

# Navigate to your plugin
cd plugin-my-plugin

# Install dependencies (automatically done by CLI)
bun install

# Start development mode with hot reloading
elizaos dev

# Or start in production mode
elizaos start

# Build your plugin for distribution
bun run build

The scaffolded plugin includes:

✅ Proper TypeScript configuration
✅ Build setup with tsup (and Vite for full plugins)
✅ Example action and provider to extend
✅ Integration with @elizaos/core
✅ Development scripts ready to use
✅ Basic tests structure

The CLI templates follow all ElizaOS conventions and best practices, making it easy to get started without worrying about configuration.

Using Your Plugin in Projects

Plugins don’t necessarily need to be in the ElizaOS monorepo. You have two options for using your plugin in a project:

Option 1: Plugin Inside the Monorepo

If you’re developing your plugin within the ElizaOS monorepo (in the packages/ directory), you need to add it as a workspace dependency:

Add your plugin to the root package.json as a workspace dependency:

{
  "dependencies": {
    "@elizaos/plugin-knowledge": "workspace:*",
    "@yourorg/plugin-myplugin": "workspace:*"
  }
}

Run bun install in the root directory to link the workspace dependency
Use the plugin in your project:

import { myPlugin } from '@yourorg/plugin-myplugin';

const agent = {
  name: 'MyAgent',
  plugins: [myPlugin],
};

Option 2: Plugin Outside the Monorepo

If you’re creating a plugin outside of the ElizaOS monorepo (recommended for most users), use bun link:

In your plugin directory, build and link it:

# In your plugin directory (e.g., plugin-myplugin/)
bun install
bun run build
bun link

In your project directory (e.g., using project-starter), link the plugin:

# In your project directory
cd packages/project-starter  # or wherever your agent project is
bun link @yourorg/plugin-myplugin

Add the plugin to your project’s package.json dependencies:

{
  "dependencies": {
    "@yourorg/plugin-myplugin": "link:@yourorg/plugin-myplugin"
  }
}

Use the plugin in your project:

import { myPlugin } from '@yourorg/plugin-myplugin';

const agent = {
  name: 'MyAgent',
  plugins: [myPlugin],
};

When using bun link, remember to rebuild your plugin (bun run build) after making changes for them to be reflected in your project.

Plugin Architecture Overview

Plugin Interface

Every plugin must implement the core Plugin interface:

import type { Plugin } from '@elizaos/core';

export interface Plugin {
  name: string;
  description: string;

  // Initialize plugin with runtime services
  init?: (config: Record<string, string>, runtime: IAgentRuntime) => Promise<void>;

  // Configuration
  config?: { [key: string]: any };

  // Services - Note: This is (typeof Service)[] not Service[]
  services?: (typeof Service)[];

  // Entity component definitions
  componentTypes?: {
    name: string;
    schema: Record<string, unknown>;
    validator?: (data: any) => boolean;
  }[];

  // Optional plugin features
  actions?: Action[];
  providers?: Provider[];
  evaluators?: Evaluator[];
  adapter?: IDatabaseAdapter;
  models?: {
    [key: string]: (...args: any[]) => Promise<any>;
  };
  events?: PluginEvents;
  routes?: Route[];
  tests?: TestSuite[];

  // Dependencies
  dependencies?: string[];
  testDependencies?: string[];

  // Plugin priority (higher priority plugins are loaded first)
  priority?: number;

  // Schema for validation
  schema?: any;
}

Directory Structure

Standard plugin structure:

packages/plugin-<name>/
├── src/
│   ├── index.ts           # Plugin manifest and exports
│   ├── service.ts         # Main service implementation
│   ├── actions/           # Agent capabilities
│   │   └── *.ts
│   ├── providers/         # Context providers
│   │   └── *.ts
│   ├── evaluators/        # Post-processing
│   │   └── *.ts
│   ├── handlers/          # LLM model handlers
│   │   └── *.ts
│   ├── types/             # TypeScript definitions
│   │   └── index.ts
│   ├── constants/         # Configuration constants
│   │   └── index.ts
│   ├── utils/             # Helper functions
│   │   └── *.ts
│   └── tests.ts           # Test suite
├── __tests__/             # Unit tests
├── package.json
├── tsconfig.json
├── tsup.config.ts
└── README.md

Core Plugin Components

1. Services

Services manage stateful connections and provide core functionality. They are singleton instances that persist throughout the agent’s lifecycle.

import { Service, IAgentRuntime, logger } from '@elizaos/core';

export class MyService extends Service {
  static serviceType = 'my-service';
  capabilityDescription = 'Description of what this service provides';

  private client: any;
  private refreshInterval: NodeJS.Timer | null = null;

  constructor(protected runtime: IAgentRuntime) {
    super();
  }

  static async start(runtime: IAgentRuntime): Promise<MyService> {
    logger.info('Initializing MyService');
    const service = new MyService(runtime);

    // Initialize connections, clients, etc.
    await service.initialize();

    // Set up periodic tasks if needed
    service.refreshInterval = setInterval(
      () => service.refreshData(),
      60000 // 1 minute
    );

    return service;
  }

  async stop(): Promise<void> {
    // Cleanup resources
    if (this.refreshInterval) {
      clearInterval(this.refreshInterval);
    }
    // Close connections
    if (this.client) {
      await this.client.disconnect();
    }
    logger.info('MyService stopped');
  }

  private async initialize(): Promise<void> {
    // Service initialization logic
    const apiKey = this.runtime.getSetting('MY_API_KEY');
    if (!apiKey) {
      throw new Error('MY_API_KEY not configured');
    }

    this.client = new MyClient({ apiKey });
    await this.client.connect();
  }
}

Service Lifecycle Patterns

Services have a specific lifecycle that plugins must respect:

1. Delayed Initialization

Sometimes services need to wait for other services or perform startup tasks:

export class MyService extends Service {
  static serviceType = 'my-service';

  static async start(runtime: IAgentRuntime): Promise<MyService> {
    const service = new MyService(runtime);

    // Immediate initialization
    await service.initialize();

    // Delayed initialization for non-critical tasks
    setTimeout(async () => {
      try {
        await service.loadCachedData();
        await service.syncWithRemote();
        logger.info('MyService: Delayed initialization complete');
      } catch (error) {
        logger.error('MyService: Delayed init failed', error);
        // Don't throw - service is still functional
      }
    }, 5000);

    return service;
  }
}

2. Actions

Actions are the heart of what your agent can DO. They’re intelligent, context-aware operations that can make decisions, interact with services, and chain together for complex workflows.

Quick Reference

Component	Purpose	Required	Returns
`name`	Unique identifier	✅	-
`description`	Help LLM understand when to use	✅	-
`similes`	Alternative names for fuzzy matching	❌	-
`validate`	Check if action can run	✅	`Promise<boolean>`
`handler`	Execute the action logic	✅	`Promise<ActionResult>`
`examples`	Teach LLM through scenarios	✅	-

Key Concepts:

Actions MUST return ActionResult with success field
Actions receive composed state from providers
Actions can chain together, passing values through state
Actions can use callbacks for intermediate responses
Actions are selected by the LLM based on validation and examples

Action Anatomy

import {
  type Action,
  type ActionExample,
  type ActionResult,
  type HandlerCallback,
  type IAgentRuntime,
  type Memory,
  type State,
  ModelType,
  composePromptFromState,
  logger,
} from '@elizaos/core';

export const myAction: Action = {
  name: 'MY_ACTION',
  description: 'Clear, concise description for the LLM to understand when to use this',

  // Similes help with fuzzy matching - be creative!
  similes: ['SIMILAR_ACTION', 'ANOTHER_NAME', 'CASUAL_REFERENCE'],

  // Validation: Can this action run in the current context?
  validate: async (runtime: IAgentRuntime, message: Memory, state?: State): Promise<boolean> => {
    // Check permissions, settings, current state, etc.
    const hasPermission = await checkUserPermissions(runtime, message);
    const serviceAvailable = runtime.getService('my-service') !== null;

    return hasPermission && serviceAvailable;
  },

  // Handler: The brain of your action
  handler: async (
    runtime: IAgentRuntime,
    message: Memory,
    state?: State,
    options?: { [key: string]: unknown },
    callback?: HandlerCallback,
    responses?: Memory[]
  ): Promise<ActionResult> => {
    // ALWAYS return ActionResult with success field!
    try {
      // Access previous action results from multi-step chains
      const context = options?.context;
      const previousResults = context?.previousResults || [];

      // Get your state (providers have already run)
      if (!state) {
        state = await runtime.composeState(message, [
          'RECENT_MESSAGES',
          'CHARACTER',
          'ACTION_STATE', // Includes previous action results
        ]);
      }

      // Your action logic here
      const result = await doSomethingAmazing();

      // Use callback for intermediate responses
      if (callback) {
        await callback({
          text: `Working on it...`,
          actions: ['MY_ACTION'],
        });
      }

      // Return structured result
      return {
        success: true, // REQUIRED field
        text: `Action completed: ${result.summary}`,
        values: {
          // These merge into state for next actions
          lastActionTime: Date.now(),
          resultData: result.data,
        },
        data: {
          // Raw data for logging/debugging
          actionName: 'MY_ACTION',
          fullResult: result,
        },
      };
    } catch (error) {
      logger.error('Action failed:', error);

      return {
        success: false, // REQUIRED field
        text: 'Failed to complete action',
        error: error instanceof Error ? error : new Error(String(error)),
        data: {
          actionName: 'MY_ACTION',
          errorDetails: error.message,
        },
      };
    }
  },

  // Examples: Teach the LLM through scenarios
  examples: [
    [
      {
        name: '{{user1}}',
        content: { text: 'Can you do the thing?' },
      },
      {
        name: '{{agent}}',
        content: {
          text: "I'll do that for you right away!",
          actions: ['MY_ACTION'],
        },
      },
    ],
  ] as ActionExample[][],
};

Real-World Action Patterns

1. Decision-Making Actions

Actions can use the LLM to make intelligent decisions based on context:

export const muteRoomAction: Action = {
  name: 'MUTE_ROOM',
  similes: ['SHUT_UP', 'BE_QUIET', 'STOP_TALKING', 'SILENCE'],
  description: 'Mutes a room if asked to or if the agent is being annoying',

  validate: async (runtime, message) => {
    // Check if already muted
    const roomState = await runtime.getParticipantUserState(message.roomId, runtime.agentId);
    return roomState !== 'MUTED';
  },

  handler: async (runtime, message, state) => {
    // Create a decision prompt
    const shouldMuteTemplate = `# Task: Should {{agentName}} mute this room?

{{recentMessages}}

Should {{agentName}} mute and stop responding unless mentioned?

Respond YES if:
- User asked to stop/be quiet
- Agent responses are annoying users
- Conversation is hostile

Otherwise NO.`;

    const prompt = composePromptFromState({ state, template: shouldMuteTemplate });
    const decision = await runtime.useModel(ModelType.TEXT_SMALL, {
      prompt,
      runtime,
    });

    if (decision.toLowerCase().includes('yes')) {
      await runtime.setParticipantUserState(message.roomId, runtime.agentId, 'MUTED');

      return {
        success: true,
        text: 'Going silent in this room',
        values: { roomMuted: true },
      };
    }

    return {
      success: true,
      text: 'Continuing to participate',
      values: { roomMuted: false },
    };
  },
};

2. Multi-Target Actions

Actions can handle complex targeting and routing:

export const sendMessageAction: Action = {
  name: 'SEND_MESSAGE',
  similes: ['DM', 'MESSAGE', 'PING', 'TELL', 'NOTIFY'],
  description: 'Send a message to a user or room on any platform',

  handler: async (runtime, message, state, options, callback) => {
    // Extract target using LLM
    const targetPrompt = composePromptFromState({
      state,
      template: `Extract message target from: {{recentMessages}}
Return JSON:
{
  "targetType": "user|room",
  "source": "platform",
  "identifiers": { "username": "...", "roomName": "..." }
}`,
    });

    const targetData = await runtime.useModel(ModelType.OBJECT_LARGE, {
      prompt: targetPrompt,
      schema: targetSchema,
    });

    // Route to appropriate service
    if (targetData.targetType === 'user') {
      const user = await findEntityByName(runtime, message, state);
      const service = runtime.getService(targetData.source);

      await service.sendDirectMessage(runtime, user.id, message.content.text);

      return {
        success: true,
        text: `Message sent to ${user.names[0]}`,
        values: { messageSent: true, targetUser: user.names[0] },
      };
    }

    // Handle room messages similarly...
  },
};

3. Stateful Reply Action

The simplest yet most important action - generating contextual responses:

export const replyAction: Action = {
  name: 'REPLY',
  similes: ['RESPOND', 'ANSWER', 'SPEAK', 'SAY'],
  description: 'Generate and send a response to the conversation',

  validate: async () => true, // Always valid

  handler: async (runtime, message, state, options, callback) => {
    // Access chain context
    const previousActions = options?.context?.previousResults || [];

    // Include dynamic providers from previous actions
    const dynamicProviders = responses?.flatMap((r) => r.content?.providers ?? []) ?? [];

    // Compose state with action results
    state = await runtime.composeState(message, [
      ...dynamicProviders,
      'RECENT_MESSAGES',
      'ACTION_STATE', // Includes previous action results
    ]);

    const replyTemplate = `# Generate response as {{agentName}}

{{providers}}

Previous actions taken: {{actionResults}}

Generate thoughtful response considering the context and any actions performed.

\`\`\`json
{
  "thought": "reasoning about response",
  "message": "the actual response"
}
\`\`\``;

    const response = await runtime.useModel(ModelType.OBJECT_LARGE, {
      prompt: composePromptFromState({ state, template: replyTemplate }),
    });

    await callback({
      text: response.message,
      thought: response.thought,
      actions: ['REPLY'],
    });

    return {
      success: true,
      text: 'Reply sent',
      values: {
        lastReply: response.message,
        thoughtProcess: response.thought,
      },
    };
  },
};

4. Permission-Based Actions

Actions that modify system state with permission checks:

export const updateRoleAction: Action = {
  name: 'UPDATE_ROLE',
  similes: ['MAKE_ADMIN', 'CHANGE_PERMISSIONS', 'PROMOTE', 'DEMOTE'],
  description: 'Update user roles with permission validation',

  validate: async (runtime, message) => {
    // Only in group contexts with server ID
    return message.content.channelType === ChannelType.GROUP && !!message.content.serverId;
  },

  handler: async (runtime, message, state) => {
    // Get requester's role
    const world = await runtime.getWorld(worldId);
    const requesterRole = world.metadata?.roles[message.entityId] || Role.NONE;

    // Extract role changes using LLM
    const changes = await runtime.useModel(ModelType.OBJECT_LARGE, {
      prompt: 'Extract role assignments from: ' + state.text,
      schema: {
        type: 'array',
        items: {
          type: 'object',
          properties: {
            entityId: { type: 'string' },
            newRole: {
              type: 'string',
              enum: ['OWNER', 'ADMIN', 'NONE'],
            },
          },
        },
      },
    });

    // Validate each change
    const results = [];
    for (const change of changes) {
      if (canModifyRole(requesterRole, currentRole, change.newRole)) {
        world.metadata.roles[change.entityId] = change.newRole;
        results.push({ success: true, ...change });
      } else {
        results.push({
          success: false,
          reason: 'Insufficient permissions',
          ...change,
        });
      }
    }

    await runtime.updateWorld(world);

    return {
      success: results.some((r) => r.success),
      text: `Updated ${results.filter((r) => r.success).length} roles`,
      data: { results },
    };
  },
};

Action Best Practices

Always Return ActionResult

// ❌ Old style - DON'T DO THIS
return true;

// ✅ New style - ALWAYS DO THIS
return {
  success: true,
  text: 'Action completed',
  values: {
    /* state updates */
  },
  data: {
    /* raw data */
  },
};

Use Callbacks for User Feedback

// Acknowledge immediately
await callback?.({
  text: "I'm working on that...",
  actions: ['MY_ACTION'],
});

// Do the work
const result = await longRunningOperation();

// Final response
await callback?.({
  text: `Done! ${result.summary}`,
  actions: ['MY_ACTION_COMPLETE'],
});

Chain Actions with Context

// Access previous results
const previousResults = options?.context?.previousResults || [];
const lastResult = previousResults[previousResults.length - 1];

if (lastResult?.data?.needsFollowUp) {
  // Continue the chain
}

Validate Thoughtfully

validate: async (runtime, message, state) => {
  // Check multiple conditions
  const hasPermission = await checkPermissions(runtime, message);
  const hasRequiredService = !!runtime.getService('required-service');
  const isRightContext = message.content.channelType === ChannelType.GROUP;

  return hasPermission && hasRequiredService && isRightContext;
};

Write Teaching Examples

examples: [
  // Show the happy path
  [
    { name: '{{user}}', content: { text: 'Please do X' } },
    {
      name: '{{agent}}',
      content: {
        text: 'Doing X now!',
        actions: ['DO_X'],
      },
    },
  ],
  // Show edge cases
  [
    { name: '{{user}}', content: { text: 'Do X without permission' } },
    {
      name: '{{agent}}',
      content: {
        text: "I don't have permission for that",
        actions: ['REPLY'],
      },
    },
  ],
  // Show the action being ignored when not relevant
  [
    { name: '{{user}}', content: { text: 'Unrelated conversation' } },
    {
      name: '{{agent}}',
      content: {
        text: 'Responding normally',
        actions: ['REPLY'],
      },
    },
  ],
];

Understanding ActionResult

The ActionResult interface is crucial for action interoperability:

interface ActionResult {
  // REQUIRED: Indicates if the action succeeded
  success: boolean;

  // Optional: User-facing message about what happened
  text?: string;

  // Optional: Values to merge into state for subsequent actions
  values?: Record<string, any>;

  // Optional: Raw data for logging/debugging
  data?: Record<string, any>;

  // Optional: Error information if action failed
  error?: string | Error;
}

Why ActionResult Matters:

State Propagation: Values from one action flow to the next
Error Handling: Consistent error reporting across all actions
Logging: Structured data for debugging and analytics
Action Chaining: Success/failure determines flow control

Action Execution Lifecycle

// 1. Provider phase - gather context
const state = await runtime.composeState(message, ['ACTIONS']);

// 2. Action selection - LLM chooses based on available actions
const validActions = await getValidActions(runtime, message, state);

// 3. Action execution - may include multiple actions
await runtime.processActions(message, responses, state, callback);

// 4. State accumulation - each action's values merge into state
// Action 1 returns: { values: { step1Complete: true } }
// Action 2 receives: state.values.step1Complete === true

// 5. Evaluator phase - post-processing
await runtime.evaluate(message, state, true, callback, responses);

Advanced Action Techniques

Dynamic Action Registration

// Actions can register other actions dynamically
export const pluginLoaderAction: Action = {
  name: 'LOAD_PLUGIN',

  handler: async (runtime, message, state) => {
    const pluginName = extractPluginName(state);
    const plugin = await import(pluginName);

    // Register new actions from the loaded plugin
    if (plugin.actions) {
      for (const action of plugin.actions) {
        runtime.registerAction(action);
      }
    }

    return {
      success: true,
      text: `Loaded ${plugin.actions.length} new actions`,
      values: {
        loadedPlugin: pluginName,
        newActions: plugin.actions.map((a) => a.name),
      },
    };
  },
};

Conditional Action Chains

export const conditionalWorkflow: Action = {
  name: 'SMART_WORKFLOW',

  handler: async (runtime, message, state, options, callback) => {
    // Step 1: Analyze
    const analysis = await analyzeRequest(state);

    if (analysis.requiresApproval) {
      // Trigger approval action
      await callback({
        text: 'This requires approval',
        actions: ['REQUEST_APPROVAL'],
      });

      return {
        success: true,
        values: {
          workflowPaused: true,
          pendingApproval: true,
        },
      };
    }

    // Step 2: Execute
    if (analysis.complexity === 'simple') {
      return await executeSimpleTask(runtime, analysis);
    } else {
      // Trigger complex workflow
      await callback({
        text: 'Starting complex workflow',
        actions: ['COMPLEX_WORKFLOW'],
      });

      return {
        success: true,
        values: {
          workflowType: 'complex',
          analysisData: analysis,
        },
      };
    }
  },
};

Action Composition

// Compose multiple actions into higher-level operations
export const compositeAction: Action = {
  name: 'SEND_AND_TRACK',
  description: 'Send a message and track its delivery',

  handler: async (runtime, message, state, options, callback) => {
    // Execute sub-actions
    const sendResult = await sendMessageAction.handler(runtime, message, state, options, callback);

    if (!sendResult.success) {
      return sendResult; // Propagate failure
    }

    // Track the sent message
    const trackingId = generateTrackingId();
    await runtime.createMemory(
      {
        id: trackingId,
        entityId: message.entityId,
        roomId: message.roomId,
        content: {
          type: 'message_tracking',
          sentTo: sendResult.data.targetId,
          sentAt: Date.now(),
          messageContent: sendResult.data.messageContent,
        },
      },
      'tracking'
    );

    return {
      success: true,
      text: `Message sent and tracked (${trackingId})`,
      values: {
        ...sendResult.values,
        trackingId,
        tracked: true,
      },
      data: {
        sendResult,
        trackingId,
      },
    };
  },
};

Self-Modifying Actions

export const learningAction: Action = {
  name: 'ADAPTIVE_RESPONSE',

  handler: async (runtime, message, state) => {
    // Retrieve past performance
    const history = await runtime.getMemories({
      tableName: 'action_feedback',
      roomId: message.roomId,
      count: 100,
    });

    // Analyze what worked well
    const analysis = await runtime.useModel(ModelType.TEXT_LARGE, {
      prompt: `Analyze these past interactions and identify patterns:
${JSON.stringify(history)}
What response strategies were most effective?`,
    });

    // Adapt behavior based on learning
    const strategy = determineStrategy(analysis);
    const response = await generateResponse(state, strategy);

    // Store for future learning
    await runtime.createMemory(
      {
        id: generateId(),
        content: {
          type: 'action_feedback',
          strategy: strategy.name,
          context: state.text,
          response: response.text,
        },
      },
      'action_feedback'
    );

    return {
      success: true,
      text: response.text,
      values: {
        strategyUsed: strategy.name,
        confidence: strategy.confidence,
      },
    };
  },
};

Testing Actions

Actions should be thoroughly tested to ensure they behave correctly in various scenarios:

// __tests__/myAction.test.ts
import { describe, it, expect, beforeEach } from 'bun:test';
import { myAction } from '../src/actions/myAction';
import { createMockRuntime } from '@elizaos/test-utils';
import { ActionResult, Memory, State } from '@elizaos/core';

describe('MyAction', () => {
  let mockRuntime: any;
  let mockMessage: Memory;
  let mockState: State;

  beforeEach(() => {
    mockRuntime = createMockRuntime({
      settings: { MY_API_KEY: 'test-key' },
    });

    mockMessage = {
      id: 'test-id',
      entityId: 'user-123',
      roomId: 'room-456',
      content: { text: 'Do the thing' },
    };

    mockState = {
      values: { recentMessages: 'test context' },
      data: { room: { name: 'Test Room' } },
      text: 'State text',
    };
  });

  describe('validation', () => {
    it('should validate when all requirements are met', async () => {
      const isValid = await myAction.validate(mockRuntime, mockMessage, mockState);
      expect(isValid).toBe(true);
    });

    it('should not validate without required service', async () => {
      mockRuntime.getService = () => null;
      const isValid = await myAction.validate(mockRuntime, mockMessage, mockState);
      expect(isValid).toBe(false);
    });
  });

  describe('handler', () => {
    it('should return success ActionResult on successful execution', async () => {
      const mockCallback = jest.fn();

      const result = await myAction.handler(mockRuntime, mockMessage, mockState, {}, mockCallback);

      expect(result.success).toBe(true);
      expect(result.text).toContain('completed');
      expect(result.values).toHaveProperty('lastActionTime');
      expect(mockCallback).toHaveBeenCalled();
    });

    it('should handle errors gracefully', async () => {
      // Make service throw error
      mockRuntime.getService = () => {
        throw new Error('Service unavailable');
      };

      const result = await myAction.handler(mockRuntime, mockMessage, mockState);

      expect(result.success).toBe(false);
      expect(result.error).toBeDefined();
      expect(result.text).toContain('Failed');
    });

    it('should access previous action results', async () => {
      const previousResults: ActionResult[] = [
        {
          success: true,
          values: { previousData: 'test' },
          data: { actionName: 'PREVIOUS_ACTION' },
        },
      ];

      const result = await myAction.handler(mockRuntime, mockMessage, mockState, {
        context: { previousResults },
      });

      // Verify it used previous results
      expect(result.values?.usedPreviousData).toBe(true);
    });
  });

  describe('examples', () => {
    it('should have valid example structure', () => {
      expect(myAction.examples).toBeDefined();
      expect(Array.isArray(myAction.examples)).toBe(true);

      // Each example should be a conversation array
      for (const example of myAction.examples!) {
        expect(Array.isArray(example)).toBe(true);

        // Each message should have name and content
        for (const message of example) {
          expect(message).toHaveProperty('name');
          expect(message).toHaveProperty('content');
        }
      }
    });
  });
});

E2E Testing Actions

For integration testing with a live runtime:

// tests/e2e/myAction.e2e.ts
export const myActionE2ETests = {
  name: 'MyAction E2E Tests',
  tests: [
    {
      name: 'should execute full action flow',
      fn: async (runtime: IAgentRuntime) => {
        // Create test message
        const message: Memory = {
          id: generateId(),
          entityId: 'test-user',
          roomId: runtime.agentId,
          content: {
            text: 'Please do the thing',
            source: 'test',
          },
        };

        // Store message
        await runtime.createMemory(message, 'messages');

        // Compose state
        const state = await runtime.composeState(message);

        // Execute action
        const result = await myAction.handler(runtime, message, state, {}, async (response) => {
          // Verify callback responses
          expect(response.text).toBeDefined();
        });

        // Verify result
        expect(result.success).toBe(true);

        // Verify side effects
        const memories = await runtime.getMemories({
          roomId: message.roomId,
          tableName: 'action_results',
          count: 1,
        });

        expect(memories.length).toBeGreaterThan(0);
      },
    },
  ],
};

3. Providers

Providers supply contextual information to the agent’s state before it makes decisions. They act as the agent’s “senses”, gathering relevant data that helps the LLM understand the current context.

import { Provider, ProviderResult, IAgentRuntime, Memory, State, addHeader } from '@elizaos/core';

export const myProvider: Provider = {
  name: 'myProvider',
  description: 'Provides contextual information about X',

  // Optional: Set to true if this provider should only run when explicitly requested
  dynamic: false,

  // Optional: Control execution order (lower numbers run first, can be negative)
  position: 100,

  // Optional: Set to true to exclude from default provider list
  private: false,

  get: async (runtime: IAgentRuntime, message: Memory, state: State): Promise<ProviderResult> => {
    try {
      const service = runtime.getService('my-service') as MyService;
      const data = await service.getCurrentData();

      // Format data for LLM context
      const formattedText = addHeader(
        '# Current System Status',
        `Field 1: ${data.field1}
Field 2: ${data.field2}
Last updated: ${new Date(data.timestamp).toLocaleString()}`
      );

      return {
        // Text that will be included in the LLM prompt
        text: formattedText,

        // Values that can be accessed by other providers/actions
        values: {
          currentField1: data.field1,
          currentField2: data.field2,
          lastUpdate: data.timestamp,
        },

        // Raw data for internal use
        data: {
          raw: data,
          processed: true,
        },
      };
    } catch (error) {
      return {
        text: 'Unable to retrieve current status',
        values: {},
        data: { error: error.message },
      };
    }
  },
};

Provider Properties

name (required): Unique identifier for the provider
description (optional): Human-readable description of what the provider does
dynamic (optional, default: false): If true, the provider is not included in default state composition and must be explicitly requested
position (optional, default: 0): Controls execution order. Lower numbers execute first. Can be negative for early execution
private (optional, default: false): If true, the provider is excluded from regular provider lists and must be explicitly included

Provider Execution Flow

Providers are executed during runtime.composeState()
By default, all non-private, non-dynamic providers are included
Providers are sorted by position and executed in order
Results are aggregated into a unified state object
The composed state is passed to actions and the LLM for decision-making

Common Provider Patterns

Recent Messages Provider (position: 100)

export const recentMessagesProvider: Provider = {
  name: 'RECENT_MESSAGES',
  description: 'Recent messages, interactions and other memories',
  position: 100, // Runs after most other providers

  get: async (runtime, message) => {
    const messages = await runtime.getMemories({
      roomId: message.roomId,
      count: runtime.getConversationLength(),
      unique: false,
    });

    const formattedMessages = formatMessages(messages);

    return {
      text: addHeader('# Conversation Messages', formattedMessages),
      values: { recentMessages: formattedMessages },
      data: { messages },
    };
  },
};

Actions Provider (position: -1)

export const actionsProvider: Provider = {
  name: 'ACTIONS',
  description: 'Possible response actions',
  position: -1, // Runs early to inform other providers

  get: async (runtime, message, state) => {
    // Get all valid actions for this context
    const validActions = await Promise.all(
      runtime.actions.map(async (action) => {
        const isValid = await action.validate(runtime, message, state);
        return isValid ? action : null;
      })
    );

    const actions = validActions.filter(Boolean);
    const actionNames = formatActionNames(actions);

    return {
      text: `Possible response actions: ${actionNames}`,
      values: { actionNames },
      data: { actionsData: actions },
    };
  },
};

Dynamic Knowledge Provider

export const knowledgeProvider: Provider = {
  name: 'KNOWLEDGE',
  description: 'Knowledge from the knowledge base',
  dynamic: true, // Only runs when explicitly requested

  get: async (runtime, message) => {
    const knowledgeService = runtime.getService('knowledge');
    const relevantKnowledge = await knowledgeService.search(message.content.text);

    if (!relevantKnowledge.length) {
      return { text: '', values: {}, data: {} };
    }

    return {
      text: addHeader('# Relevant Knowledge', formatKnowledge(relevantKnowledge)),
      values: { knowledgeUsed: true },
      data: { knowledge: relevantKnowledge },
    };
  },
};

4. Evaluators

Evaluators run after the agent generates a response, allowing for analysis, learning, and side effects. They use the same handler pattern as actions but run post-response.

import { Evaluator, IAgentRuntime, Memory, State, HandlerCallback } from '@elizaos/core';

export const myEvaluator: Evaluator = {
  name: 'myEvaluator',
  description: 'Analyzes responses for quality and extracts insights',

  // Examples help the LLM understand when to use this evaluator
  examples: [
    {
      prompt: 'User asks about product pricing',
      messages: [
        { name: 'user', content: { text: 'How much does it cost?' } },
        { name: 'assistant', content: { text: 'The price is $99' } },
      ],
      outcome: 'Extract pricing information for future reference',
    },
  ],

  // Similar descriptions for fuzzy matching
  similes: ['RESPONSE_ANALYZER', 'QUALITY_CHECK'],

  // Optional: Run even if the agent didn't respond
  alwaysRun: false,

  // Validation: Determines if evaluator should run
  validate: async (runtime: IAgentRuntime, message: Memory, state?: State): Promise<boolean> => {
    // Example: Only run for certain types of responses
    return message.content?.text?.includes('transaction') || false;
  },

  // Handler: Main evaluation logic
  handler: async (
    runtime: IAgentRuntime,
    message: Memory,
    state?: State,
    options?: { [key: string]: unknown },
    callback?: HandlerCallback,
    responses?: Memory[]
  ): Promise<void> => {
    try {
      // Analyze the response
      const responseText = responses?.[0]?.content?.text || '';

      if (responseText.includes('transaction')) {
        // Extract and store transaction data
        const txHash = extractTransactionHash(responseText);

        if (txHash) {
          // Store for future reference
          await runtime.createMemory(
            {
              id: generateId(),
              entityId: message.entityId,
              roomId: message.roomId,
              content: {
                text: `Transaction processed: ${txHash}`,
                type: 'transaction_record',
                data: { txHash, timestamp: Date.now() },
              },
            },
            'facts'
          );

          // Log the evaluation
          await runtime.adapter.log({
            entityId: message.entityId,
            roomId: message.roomId,
            type: 'evaluator',
            body: {
              evaluator: 'myEvaluator',
              result: 'transaction_extracted',
              txHash,
            },
          });
        }
      }

      // Can also trigger follow-up actions via callback
      if (callback) {
        callback({
          text: 'Analysis complete',
          content: { analyzed: true },
        });
      }
    } catch (error) {
      runtime.logger.error('Evaluator error:', error);
    }
  },
};

Common Evaluator Patterns

Fact Extraction Evaluator

export const factExtractor: Evaluator = {
  name: 'FACT_EXTRACTOR',
  description: 'Extracts facts from conversations for long-term memory',
  alwaysRun: true, // Run after every response

  validate: async () => true, // Always valid

  handler: async (runtime, message, state, options, callback, responses) => {
    const facts = await extractFactsFromConversation(runtime, message, responses);

    for (const fact of facts) {
      await runtime.createMemory(
        {
          id: generateId(),
          entityId: message.entityId,
          roomId: message.roomId,
          content: {
            text: fact.statement,
            type: 'fact',
            confidence: fact.confidence,
          },
        },
        'facts',
        true
      ); // unique = true to avoid duplicates
    }
  },
};

Response Quality Evaluator

export const qualityEvaluator: Evaluator = {
  name: 'QUALITY_CHECK',
  description: 'Evaluates response quality and coherence',

  validate: async (runtime, message) => {
    // Only evaluate responses to direct questions
    return message.content?.text?.includes('?') || false;
  },

  handler: async (runtime, message, state, options, callback, responses) => {
    const quality = await assessResponseQuality(responses[0]);

    if (quality.score < 0.7) {
      // Log low quality response for review
      await runtime.adapter.log({
        entityId: message.entityId,
        roomId: message.roomId,
        type: 'quality_alert',
        body: {
          score: quality.score,
          issues: quality.issues,
          responseId: responses[0].id,
        },
      });
    }
  },
};

Understanding the Agent Lifecycle: Providers, Actions, and Evaluators

When an agent receives a message, components execute in this order:

Providers gather context by calling runtime.composeState()
- Non-private, non-dynamic providers run automatically
- Sorted by position (lower numbers first)
- Results aggregated into state object
Actions are validated and presented to the LLM
- The actions provider lists available actions
- LLM decides which actions to execute
- Actions execute with the composed state
Evaluators run after response generation
- Process the response for insights
- Can store memories, log events, or trigger follow-ups
- Use alwaysRun: true to run even without a response

// Example flow in pseudocode
async function processMessage(message: Memory) {
  // 1. Compose state with providers
  const state = await runtime.composeState(message, ['RECENT_MESSAGES', 'CHARACTER', 'ACTIONS']);

  // 2. Generate response using LLM with composed state
  const response = await generateResponse(state);

  // 3. Execute any actions the LLM chose
  if (response.actions?.length > 0) {
    await runtime.processActions(message, [response], state);
  }

  // 4. Run evaluators on the response
  await runtime.evaluate(message, state, true, callback, [response]);
}

Accessing Provider Data in Actions

Actions receive the composed state containing all provider data. Here’s how to access it:

export const myAction: Action = {
  name: 'MY_ACTION',

  handler: async (runtime, message, state, options, callback) => {
    // Access provider values
    const recentMessages = state.values?.recentMessages;
    const actionNames = state.values?.actionNames;

    // Access raw provider data
    const providerData = state.data?.providers;
    if (providerData) {
      // Get specific provider's data
      const knowledgeData = providerData['KNOWLEDGE']?.data;
      const characterData = providerData['CHARACTER']?.data;
    }

    // Access action execution context
    const previousResults = state.data?.actionResults || [];
    const actionPlan = state.data?.actionPlan;

    // Use the data to make decisions
    if (state.values?.knowledgeUsed) {
      // Knowledge was found, incorporate it
    }
  },
};

Custom Provider Inclusion

To include specific providers when composing state:

// Include only specific providers
const state = await runtime.composeState(message, ['CHARACTER', 'KNOWLEDGE'], true);

// Add extra providers to the default set
const state = await runtime.composeState(message, ['KNOWLEDGE', 'CUSTOM_PROVIDER']);

// Skip cache and regenerate
const state = await runtime.composeState(message, null, false, true);

5. Model Handlers (LLM Plugins)

For LLM plugins, implement model handlers for different model types:

import { ModelType, GenerateTextParams, EventType } from '@elizaos/core';

export const models = {
  [ModelType.TEXT_SMALL]: async (
    runtime: IAgentRuntime,
    params: GenerateTextParams
  ): Promise<string> => {
    const client = createClient(runtime);
    const { text, usage } = await client.generateText({
      model: getSmallModel(runtime),
      prompt: params.prompt,
      temperature: params.temperature ?? 0.7,
      maxTokens: params.maxTokens ?? 4096,
    });

    // Emit usage event
    runtime.emitEvent(EventType.MODEL_USED, {
      provider: 'my-llm',
      type: ModelType.TEXT_SMALL,
      tokens: usage,
    });

    return text;
  },

  [ModelType.TEXT_EMBEDDING]: async (
    runtime: IAgentRuntime,
    params: TextEmbeddingParams | string | null
  ): Promise<number[]> => {
    if (params === null) {
      // Return test embedding
      return Array(1536).fill(0);
    }

    const text = typeof params === 'string' ? params : params.text;
    const embedding = await client.createEmbedding(text);
    return embedding;
  },
};

6. HTTP Routes and API Endpoints

Plugins can expose HTTP endpoints for webhooks, APIs, or web interfaces. Routes are defined using the Route type and exported as part of the plugin:

import { Plugin, Route, IAgentRuntime } from '@elizaos/core';

// Define route handlers
async function statusHandler(req: any, res: any, runtime: IAgentRuntime) {
  try {
    const service = runtime.getService('my-service') as MyService;
    const status = await service.getStatus();

    res.writeHead(200, { 'Content-Type': 'application/json' });
    res.end(
      JSON.stringify({
        success: true,
        data: status,
        timestamp: new Date().toISOString(),
      })
    );
  } catch (error) {
    res.writeHead(500, { 'Content-Type': 'application/json' });
    res.end(
      JSON.stringify({
        success: false,
        error: error.message,
      })
    );
  }
}

// Export routes array
export const myPluginRoutes: Route[] = [
  {
    type: 'GET',
    path: '/api/status',
    handler: statusHandler,
    public: true, // Makes this route discoverable in UI
    name: 'API Status', // Display name for UI tab
  },
  {
    type: 'POST',
    path: '/api/webhook',
    handler: webhookHandler,
  },
];

// Include routes in plugin definition
export const myPlugin: Plugin = {
  name: 'my-plugin',
  description: 'My plugin with HTTP routes',
  services: [MyService],
  routes: myPluginRoutes, // Add routes here
};

Response Helpers

Create consistent API responses:

// Helper functions for standardized responses
function sendSuccess(res: any, data: any, status = 200) {
  res.writeHead(status, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({ success: true, data }));
}

function sendError(res: any, status: number, message: string, details?: any) {
  res.writeHead(status, { 'Content-Type': 'application/json' });
  res.end(
    JSON.stringify({
      success: false,
      error: { message, details },
    })
  );
}

// Use in handlers
async function apiHandler(req: any, res: any, runtime: IAgentRuntime) {
  try {
    const result = await processRequest(req.body);
    sendSuccess(res, result);
  } catch (error) {
    sendError(res, 500, 'Processing failed', error.message);
  }
}

Authentication Patterns

Implement authentication in route handlers:

async function authenticatedHandler(req: any, res: any, runtime: IAgentRuntime) {
  // Check API key from headers
  const apiKey = req.headers['x-api-key'];
  const validKey = runtime.getSetting('API_KEY');

  if (!apiKey || apiKey !== validKey) {
    sendError(res, 401, 'Unauthorized');
    return;
  }

  // Process authenticated request
  const data = await processAuthenticatedRequest(req);
  sendSuccess(res, data);
}

File Upload Support

Handle multipart form data:

// The server automatically applies multer middleware for multipart routes
export const uploadRoute: Route = {
  type: 'POST',
  path: '/api/upload',
  handler: async (req: any, res: any, runtime: IAgentRuntime) => {
    // Access uploaded files via req.files
    const files = req.files as Express.Multer.File[];

    if (!files || files.length === 0) {
      sendError(res, 400, 'No files uploaded');
      return;
    }

    // Process uploaded files
    for (const file of files) {
      await processFile(file.buffer, file.originalname);
    }

    sendSuccess(res, { processed: files.length });
  },
  isMultipart: true, // Enable multipart handling
};

Advanced: Creating Plugins Manually

For developers working within the ElizaOS monorepo or those who need complete control over their plugin structure, you can create plugins manually. This approach is useful when:

Contributing directly to the ElizaOS monorepo
Creating highly customized plugin structures
Integrating with existing codebases
Learning the internals of plugin architecture

Step 1: Set Up the Project

# Create plugin directory
mkdir packages/plugin-myplugin
cd packages/plugin-myplugin

# Initialize package.json
bun init -y

# Install dependencies
bun add @elizaos/core zod
bun add -d typescript tsup @types/node @types/bun

# Create directory structure
mkdir -p src/{actions,providers,types,constants}

Step 2: Configure package.json

{
  "name": "@yourorg/plugin-myplugin",
  "version": "1.0.0",
  "type": "module",
  "main": "dist/index.js",
  "types": "dist/index.d.ts",
  "exports": {
    ".": {
      "import": {
        "types": "./dist/index.d.ts",
        "default": "./dist/index.js"
      }
    }
  },
  "files": ["dist"],
  "scripts": {
    "build": "tsup",
    "dev": "tsup --watch",
    "test": "bun test",
    "test:watch": "bun test --watch",
    "test:coverage": "bun test --coverage",
    "lint": "eslint ./src --ext .ts",
    "format": "prettier --write ./src"
  },
  "dependencies": {
    "@elizaos/core": "^1.0.0",
    "zod": "^3.24.2"
  },
  "devDependencies": {
    "typescript": "^5.8.3",
    "tsup": "^8.4.0",
    "@types/bun": "^1.2.16",
    "@types/node": "^22.15.3"
  },
  "agentConfig": {
    "pluginType": "elizaos:plugin:1.0.0",
    "pluginParameters": {
      "MY_API_KEY": {
        "type": "string",
        "description": "API key for MyPlugin",
        "required": true,
        "sensitive": true
      }
    }
  }
}

Step 3: Create TypeScript Configuration

// tsconfig.json
{
  "extends": "../../tsconfig.json",
  "compilerOptions": {
    "outDir": "./dist",
    "rootDir": "./src"
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "dist"]
}

// tsup.config.ts
import { defineConfig } from 'tsup';

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['esm'],
  dts: true,
  splitting: false,
  sourcemap: true,
  clean: true,
  external: ['@elizaos/core'],
});

# bunfig.toml
[install]
# Optional: Configure registry
# registry = "https://registry.npmjs.org"

# Optional: Save exact versions
save-exact = true

# Optional: Configure trusted dependencies for postinstall scripts
# trustedDependencies = ["package-name"]

Step 4: Implement the Plugin

// src/index.ts
import type { Plugin } from '@elizaos/core';
import { MyService } from './service';
import { myAction } from './actions/myAction';
import { myProvider } from './providers/myProvider';

export const myPlugin: Plugin = {
  name: 'myplugin',
  description: 'My custom plugin for ElizaOS',
  services: [MyService], // Pass the class constructor, not an instance
  actions: [myAction],
  providers: [myProvider],
  routes: myPluginRoutes, // Optional: HTTP endpoints

  init: async (config: Record<string, string>, runtime: IAgentRuntime) => {
    // Optional initialization logic
    logger.info('MyPlugin initialized');
  },
};

export default myPlugin;

Plugin Types and Patterns

Plugin Dependencies and Priority

Plugins can declare dependencies on other plugins and control their loading order:

export const myPlugin: Plugin = {
  name: 'my-plugin',
  description: 'Plugin that depends on other plugins',

  // Required dependencies - plugin won't load without these
  dependencies: ['plugin-sql', 'plugin-bootstrap'],

  // Optional test dependencies
  testDependencies: ['plugin-test-utils'],

  // Higher priority = loads earlier (default: 0)
  priority: 100,

  async init(config, runtime) {
    // Dependencies are guaranteed to be loaded
    const sqlService = runtime.getService('sql');
    if (!sqlService) {
      throw new Error('SQL service not found despite dependency');
    }
  },
};

Checking for Optional Dependencies

async init(config, runtime) {
  // Check if optional plugin is available
  const hasKnowledgePlugin = runtime.getService('knowledge') !== null;

  if (hasKnowledgePlugin) {
    logger.info('Knowledge plugin detected, enabling enhanced features');
    this.enableKnowledgeIntegration = true;
  }
}

Platform Plugins

Platform plugins connect agents to communication platforms:

// Key patterns for platform plugins:
// 1. Entity mapping (server → world, channel → room, user → entity)
// 2. Message conversion
// 3. Event handling
// 4. Rate limiting

export class PlatformService extends Service {
  private client: PlatformClient;
  private messageManager: MessageManager;

  async handleIncomingMessage(platformMessage: any) {
    // 1. Sync entities
    const { worldId, roomId, userId } = await this.syncEntities(platformMessage);

    // 2. Convert to Memory
    const memory = await this.messageManager.convertToMemory(platformMessage, roomId, userId);

    // 3. Process through runtime
    await this.runtime.processMemory(memory);

    // 4. Emit events
    await this.runtime.emit(EventType.MESSAGE_RECEIVED, memory);
  }
}

LLM Plugins

LLM plugins integrate different AI model providers:

// Key patterns for LLM plugins:
// 1. Model type handlers
// 2. Configuration management
// 3. Usage tracking
// 4. Error handling

export const llmPlugin: Plugin = {
  name: 'my-llm',
  models: {
    [ModelType.TEXT_LARGE]: async (runtime, params) => {
      const client = createClient(runtime);
      const response = await client.generate(params);

      // Track usage
      runtime.emitEvent(EventType.MODEL_USED, {
        provider: 'my-llm',
        tokens: response.usage,
      });

      return response.text;
    },
  },
};

Event Handling

Plugins can register event handlers to react to system events:

import { EventType, EventHandler } from '@elizaos/core';

export const myPlugin: Plugin = {
  name: 'my-plugin',

  events: {
    // Handle message events
    [EventType.MESSAGE_CREATED]: [
      async (params) => {
        logger.info('New message created:', params.message.id);
        // React to new messages
      },
    ],

    // Handle custom events
    'custom:data-sync': [
      async (params) => {
        await syncDataWithExternal(params);
      },
    ],
  },

  async init(config, runtime) {
    // Emit custom events
    runtime.emitEvent('custom:data-sync', {
      timestamp: Date.now(),
      source: 'my-plugin',
    });
  },
};

DeFi Plugins

DeFi plugins enable blockchain interactions:

// Key patterns for DeFi plugins:
// 1. Wallet management
// 2. Transaction handling
// 3. Gas optimization
// 4. Security validation

export class DeFiService extends Service {
  private walletClient: WalletClient;
  private publicClient: PublicClient;

  async executeTransaction(params: TransactionParams) {
    // 1. Validate inputs
    validateAddress(params.to);
    validateAmount(params.amount);

    // 2. Estimate gas
    const gasLimit = await this.estimateGas(params);

    // 3. Execute with retry
    return await withRetry(() =>
      this.walletClient.sendTransaction({
        ...params,
        gasLimit,
      })
    );
  }
}

Advanced Configuration

Configuration Hierarchy

ElizaOS follows a specific hierarchy for configuration resolution. Understanding this is critical for proper plugin behavior:

// Configuration resolution order (first found wins):
// 1. Runtime settings (via runtime.getSetting())
// 2. Environment variables (process.env)
// 3. Plugin config defaults
// 4. Hardcoded defaults

// IMPORTANT: During init(), runtime might not be fully available!
export async function getConfigValue(
  key: string,
  runtime?: IAgentRuntime,
  defaultValue?: string
): Promise<string | undefined> {
  // Try runtime first (if available)
  if (runtime) {
    const runtimeValue = runtime.getSetting(key);
    if (runtimeValue !== undefined) return runtimeValue;
  }

  // Fall back to environment
  const envValue = process.env[key];
  if (envValue !== undefined) return envValue;

  // Use default
  return defaultValue;
}

Init-time vs Runtime Configuration

During plugin initialization, configuration access is different:

export const myPlugin: Plugin = {
  name: 'my-plugin',

  // Plugin-level config defaults
  config: {
    DEFAULT_TIMEOUT: 30000,
    RETRY_ATTEMPTS: 3,
  },

  async init(config: Record<string, string>, runtime?: IAgentRuntime) {
    // During init, runtime might not be available or fully initialized
    // Always check multiple sources:

    const apiKey =
      config.API_KEY || // From agent character config
      runtime?.getSetting('API_KEY') || // From runtime (may be undefined)
      process.env.API_KEY; // From environment

    if (!apiKey) {
      throw new Error('API_KEY required for my-plugin');
    }

    // For boolean values, be careful with string parsing
    const isEnabled =
      config.FEATURE_ENABLED === 'true' ||
      runtime?.getSetting('FEATURE_ENABLED') === 'true' ||
      process.env.FEATURE_ENABLED === 'true';
  },
};

Configuration Validation

Use Zod for runtime validation:

import { z } from 'zod';

export const configSchema = z.object({
  API_KEY: z.string().min(1, 'API key is required'),
  ENDPOINT_URL: z.string().url().optional(),
  TIMEOUT: z.number().positive().default(30000),
});

export async function validateConfig(runtime: IAgentRuntime) {
  const config = {
    API_KEY: runtime.getSetting('MY_API_KEY'),
    ENDPOINT_URL: runtime.getSetting('MY_ENDPOINT_URL'),
    TIMEOUT: Number(runtime.getSetting('MY_TIMEOUT') || 30000),
  };

  return configSchema.parse(config);
}

agentConfig in package.json

Declare plugin parameters:

{
  "agentConfig": {
    "pluginType": "elizaos:plugin:1.0.0",
    "pluginParameters": {
      "MY_API_KEY": {
        "type": "string",
        "description": "API key for authentication",
        "required": true,
        "sensitive": true
      },
      "MY_TIMEOUT": {
        "type": "number",
        "description": "Request timeout in milliseconds",
        "required": false,
        "default": 30000
      }
    }
  }
}

Testing Strategies

Bun provides a built-in test runner that’s fast and compatible with Jest-like syntax. No need for additional testing frameworks.

Unit Tests

Test individual components:

// __tests__/myAction.test.ts
import { describe, it, expect, mock, beforeEach } from 'bun:test';
import { myAction } from '../src/actions/myAction';
import { createMockRuntime } from '@elizaos/test-utils';

describe('MyAction', () => {
  beforeEach(() => {
    // Reset all mocks before each test
    mock.restore();
  });

  it('should validate when configured', async () => {
    const mockRuntime = createMockRuntime({
      settings: {
        MY_API_KEY: 'test-key',
      },
    });

    const isValid = await myAction.validate(mockRuntime);
    expect(isValid).toBe(true);
  });

  it('should handle action execution', async () => {
    const mockRuntime = createMockRuntime();
    const mockService = {
      executeAction: mock().mockResolvedValue({ success: true }),
    };

    mockRuntime.getService = mock().mockReturnValue(mockService);

    const callback = mock();
    const result = await myAction.handler(mockRuntime, mockMessage, mockState, {}, callback);

    expect(result).toBe(true);
    expect(callback).toHaveBeenCalledWith({
      text: expect.stringContaining('Successfully'),
      content: expect.objectContaining({ success: true }),
    });
  });
});

Integration Tests

Test component interactions:

describe('Plugin Integration', () => {
  let runtime: IAgentRuntime;
  let service: MyService;

  beforeAll(async () => {
    runtime = await createTestRuntime({
      settings: {
        MY_API_KEY: process.env.TEST_API_KEY,
      },
    });

    service = await MyService.start(runtime);
  });

  it('should handle complete flow', async () => {
    const message = createTestMessage('Execute my action');
    const response = await runtime.processMessage(message);

    expect(response.success).toBe(true);
  });
});

Test Suite Implementation

Include tests in your plugin:

export class MyPluginTestSuite implements TestSuite {
  name = 'myplugin';
  tests: Array<{ name: string; fn: (runtime: IAgentRuntime) => Promise<void> }>;

  constructor() {
    this.tests = [
      {
        name: 'Test initialization',
        fn: this.testInitialization.bind(this),
      },
      {
        name: 'Test action execution',
        fn: this.testActionExecution.bind(this),
      },
    ];
  }

  private async testInitialization(runtime: IAgentRuntime): Promise<void> {
    const service = runtime.getService('my-service') as MyService;
    if (!service) {
      throw new Error('Service not initialized');
    }

    const isConnected = await service.isConnected();
    if (!isConnected) {
      throw new Error('Failed to connect');
    }
  }
}

Security Best Practices

1. Credential Management

// Never hardcode credentials
// ❌ BAD
const apiKey = 'sk-1234...';

// ✅ GOOD
const apiKey = runtime.getSetting('API_KEY');
if (!apiKey) {
  throw new Error('API_KEY not configured');
}

2. Input Validation

function validateInput(input: any): ValidatedInput {
  // Validate types
  if (typeof input.address !== 'string') {
    throw new Error('Invalid address type');
  }

  // Validate format
  if (!isValidAddress(input.address)) {
    throw new Error('Invalid address format');
  }

  // Sanitize input
  const sanitized = {
    address: input.address.toLowerCase().trim(),
    amount: Math.abs(parseFloat(input.amount)),
  };

  return sanitized;
}

3. Rate Limiting

class RateLimiter {
  private requests = new Map<string, number[]>();

  canExecute(userId: string, limit = 10, window = 60000): boolean {
    const now = Date.now();
    const userRequests = this.requests.get(userId) || [];

    const recentRequests = userRequests.filter((time) => now - time < window);

    if (recentRequests.length >= limit) {
      return false;
    }

    recentRequests.push(now);
    this.requests.set(userId, recentRequests);
    return true;
  }
}

4. Error Handling

export class PluginError extends Error {
  constructor(message: string, public code: string, public details?: any) {
    super(message);
    this.name = 'PluginError';
  }
}

async function handleOperation<T>(operation: () => Promise<T>, context: string): Promise<T> {
  try {
    return await operation();
  } catch (error) {
    logger.error(`Error in ${context}:`, error);

    if (error.code === 'NETWORK_ERROR') {
      throw new PluginError('Network connection failed', 'NETWORK_ERROR', { context });
    }

    throw new PluginError('An unexpected error occurred', 'UNKNOWN_ERROR', {
      context,
      originalError: error,
    });
  }
}

Publishing and Distribution

For detailed information on publishing your plugin to npm and the ElizaOS registry, see our Plugin Publishing Guide.

Quick Reference

# Test your plugin
elizaos test

# Dry run to verify everything
elizaos publish --test

# Publish to npm and registry
elizaos publish --npm

The Plugin Publishing Guide covers the complete process including:

Pre-publication validation
npm authentication
GitHub repository setup
Registry PR submission
Post-publication updates

Reference Examples

Minimal Plugin

// Minimal viable plugin
import { Plugin } from '@elizaos/core';

export const minimalPlugin: Plugin = {
  name: 'minimal',
  description: 'A minimal plugin example',
  actions: [
    {
      name: 'HELLO',
      description: 'Says hello',
      validate: async () => true,
      handler: async (runtime, message, state, options, callback) => {
        callback?.({ text: 'Hello from minimal plugin!' });
        return true;
      },
      examples: [],
    },
  ],
};

export default minimalPlugin;

Complete Templates

Quick Start Templates: Use elizaos create for instant plugin scaffolding with pre-configured TypeScript, build tools, and example components

Common Patterns and Utilities

Retry Logic

async function withRetry<T>(fn: () => Promise<T>, maxRetries = 3, delay = 1000): Promise<T> {
  let lastError: Error;

  for (let i = 0; i < maxRetries; i++) {
    try {
      return await fn();
    } catch (error) {
      lastError = error;
      if (i < maxRetries - 1) {
        await new Promise((resolve) => setTimeout(resolve, delay * (i + 1)));
      }
    }
  }

  throw lastError!;
}

Troubleshooting

Common Issues

Plugin not loading: Check that the plugin is properly exported and listed in the agent’s plugins array
Configuration errors: Verify all required settings are provided
Type errors: Ensure @elizaos/core version matches other plugins
Runtime errors: Check service initialization and error handling

Debug Tips

// Enable detailed logging
import { elizaLogger } from '@elizaos/core';

elizaLogger.level = 'debug';

// Add debug logging
elizaLogger.debug('Plugin state:', {
  service: !!runtime.getService('my-service'),
  settings: runtime.getSetting('MY_API_KEY') ? 'set' : 'missing',
});

Bun-Specific Tips

When developing plugins with Bun:

Fast Installation: Bun’s package installation is significantly faster than npm
Built-in TypeScript: No need for separate TypeScript compilation during development
Native Test Runner: Use bun test for running tests without additional setup (no vitest needed)
Workspace Support: Bun handles monorepo workspaces efficiently
Lock File: Bun uses bun.lockb (binary format) for faster dependency resolution

Bun Test Features

Bun’s built-in test runner provides:

Jest-compatible API (describe, it, expect, mock)
Built-in mocking with mock() from ‘bun:test’
Fast execution with no compilation step
Coverage reports with --coverage flag
Watch mode with --watch flag
Snapshot testing support

Test File Conventions

Bun automatically discovers test files matching these patterns:

*.test.ts or *.test.js
*.spec.ts or *.spec.js
Files in __tests__/ directories
Files in test/ or tests/ directories

Useful Bun Commands for Plugin Development

# Install all dependencies
bun install

# Add a new dependency
bun add <package-name>

# Add a dev dependency
bun add -d <package-name>

# Run scripts
bun run <script-name>

# Run tests
bun test

# Update dependencies
bun update

# Clean install (remove node_modules and reinstall)
bun install --force

Best Practices Summary

Architecture: Follow the standard plugin structure
Type Safety: Use TypeScript strictly
Error Handling: Always handle errors gracefully
Configuration: Use runtime.getSetting() for all config
Testing: Write comprehensive unit and integration tests
Security: Never hardcode sensitive data
Documentation: Provide clear usage examples
Performance: Implement caching and rate limiting
Logging: Use appropriate log levels
Versioning: Follow semantic versioning

Getting Help

Documentation: Check the main ElizaOS docs
Examples: Study existing plugins in packages/
Community: Join the ElizaOS Discord
Issues: Report bugs on GitHub

Remember: The plugin system is designed to be flexible and extensible. When in doubt, look at existing plugins for patterns and inspiration.

Get Started

Core Concepts

Deep Dive

Guides

​Table of Contents

​Introduction

​What Can Plugins Do?

​Quick Start: Scaffolding Plugins with CLI

​Using elizaos create

​Quick Plugin Structure

​Full Plugin Structure

​After Scaffolding

​Using Your Plugin in Projects

​Option 1: Plugin Inside the Monorepo

​Option 2: Plugin Outside the Monorepo

​Plugin Architecture Overview

​Plugin Interface

​Directory Structure

​Core Plugin Components

​1. Services

​Service Lifecycle Patterns

​1. Delayed Initialization

​2. Actions

​Quick Reference

​Action Anatomy

​Real-World Action Patterns

1. Decision-Making Actions

2. Multi-Target Actions

3. Stateful Reply Action

4. Permission-Based Actions

​Action Best Practices

​Understanding ActionResult

​Action Execution Lifecycle

​Advanced Action Techniques

Dynamic Action Registration

Conditional Action Chains

Action Composition

Self-Modifying Actions

​Testing Actions

E2E Testing Actions

​3. Providers

​Provider Properties

​Provider Execution Flow

​Common Provider Patterns

​4. Evaluators

​Common Evaluator Patterns

​Understanding the Agent Lifecycle: Providers, Actions, and Evaluators

​Accessing Provider Data in Actions

​Custom Provider Inclusion

​5. Model Handlers (LLM Plugins)

​6. HTTP Routes and API Endpoints

​Response Helpers

​Authentication Patterns

​File Upload Support

​Advanced: Creating Plugins Manually

​Step 1: Set Up the Project

​Step 2: Configure package.json

​Step 3: Create TypeScript Configuration

​Step 4: Implement the Plugin

​Plugin Types and Patterns

​Plugin Dependencies and Priority

​Checking for Optional Dependencies

​Platform Plugins

​LLM Plugins

​Event Handling

​DeFi Plugins

​Advanced Configuration

​Configuration Hierarchy

​Init-time vs Runtime Configuration

​Configuration Validation

​agentConfig in package.json

​Testing Strategies

​Unit Tests

​Integration Tests

​Test Suite Implementation

​Security Best Practices

​1. Credential Management

​2. Input Validation

​3. Rate Limiting

​4. Error Handling

Table of Contents

Introduction

What Can Plugins Do?

Quick Start: Scaffolding Plugins with CLI

Using `elizaos create`

Quick Plugin Structure

Full Plugin Structure

After Scaffolding

Using Your Plugin in Projects

Option 1: Plugin Inside the Monorepo

Option 2: Plugin Outside the Monorepo

Plugin Architecture Overview

Plugin Interface

Directory Structure

Core Plugin Components

1. Services

Service Lifecycle Patterns

1. Delayed Initialization

2. Actions

Quick Reference

Action Anatomy

Real-World Action Patterns

Action Best Practices

Understanding ActionResult

Action Execution Lifecycle

Advanced Action Techniques

Testing Actions

3. Providers

Provider Properties

Provider Execution Flow

Common Provider Patterns

4. Evaluators

Common Evaluator Patterns

Understanding the Agent Lifecycle: Providers, Actions, and Evaluators

Accessing Provider Data in Actions

Custom Provider Inclusion

5. Model Handlers (LLM Plugins)

6. HTTP Routes and API Endpoints

Response Helpers

Authentication Patterns

File Upload Support

Advanced: Creating Plugins Manually

Step 1: Set Up the Project

Step 2: Configure package.json

Step 3: Create TypeScript Configuration

Step 4: Implement the Plugin

Plugin Types and Patterns

Plugin Dependencies and Priority

Checking for Optional Dependencies

Platform Plugins

LLM Plugins

Event Handling

DeFi Plugins

Advanced Configuration

Configuration Hierarchy

Init-time vs Runtime Configuration

Configuration Validation

agentConfig in package.json

Testing Strategies

Unit Tests

Integration Tests

Test Suite Implementation

Security Best Practices

1. Credential Management

2. Input Validation

3. Rate Limiting

4. Error Handling

Publishing and Distribution

Quick Reference

Reference Examples

Minimal Plugin

Complete Templates

Common Patterns and Utilities

Retry Logic

Troubleshooting

Common Issues

Debug Tips

Bun-Specific Tips

Bun Test Features

Test File Conventions