Runtime and Lifecycle - ElizaOS Documentation

Agent Lifecycle Overview

The journey from a static Character configuration to a live, interactive Agent involves several distinct phases, each managed by the AgentRuntime. For character structure details, see Character Interface.

Character to Agent Transformation

Loading Characters

Characters can be loaded from various sources:

// From TypeScript file
import { character } from './character';

// From JSON file
import characterJson from './character.json';

// From environment
const character = {
  name: process.env.AGENT_NAME || 'DefaultAgent',
  bio: process.env.AGENT_BIO || 'A helpful assistant',
  // ... other properties from env
};

// Dynamic loading
async function loadCharacter(source: string): Promise<Character> {
  if (source.endsWith('.json')) {
    const data = await fs.readFile(source, 'utf-8');
    return JSON.parse(data);
  } else if (source.endsWith('.ts')) {
    const module = await import(source);
    return module.character || module.default;
  } else if (source.startsWith('http')) {
    const response = await fetch(source);
    return await response.json();
  }
  
  throw new Error(`Unknown character source: ${source}`);
}

Character Validation

Before creating an agent, the character must be validated:

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

function validateAndPrepareCharacter(character: Partial<Character>): Character {
  // Required fields
  if (!character.name) {
    throw new Error('Character name is required');
  }
  
  if (!character.bio || (Array.isArray(character.bio) && character.bio.length === 0)) {
    throw new Error('Character bio is required');
  }
  
  // Set defaults
  const prepared: Character = {
    ...character,
    id: character.id || stringToUuid(character.name),
    username: character.username || character.name.toLowerCase().replace(/\s+/g, '_'),
    topics: character.topics || [],
    adjectives: character.adjectives || [],
    messageExamples: character.messageExamples || [],
    postExamples: character.postExamples || [],
    style: {
      all: character.style?.all || [],
      chat: character.style?.chat || [],
      post: character.style?.post || [],
    },
    settings: character.settings || {},
    secrets: character.secrets || {},
    plugins: character.plugins || [],
  };
  
  // Validate structure
  const validation = validateCharacter(prepared);
  if (!validation.valid) {
    throw new Error(`Character validation failed: ${validation.errors.join(', ')}`);
  }
  
  return prepared;
}

Agent Instantiation

The transformation from Character to Agent:

interface Agent extends Character {
  enabled?: boolean;
  status?: AgentStatus;
  createdAt: number;
  updatedAt: number;
}

enum AgentStatus {
  ACTIVE = 'active',
  INACTIVE = 'inactive',
}

// Creating an Agent from a Character
function createAgent(character: Character): Agent {
  return {
    ...character,
    enabled: true,
    status: AgentStatus.INACTIVE,  // Will become ACTIVE after initialization
    createdAt: Date.now(),
    updatedAt: Date.now()
  };
}

Runtime Architecture

AgentRuntime Core

The AgentRuntime is the central orchestrator:

export class AgentRuntime implements IAgentRuntime {
  readonly agentId: UUID;
  readonly character: Character;
  public adapter!: IDatabaseAdapter;
  readonly actions: Action[] = [];
  readonly evaluators: Evaluator[] = [];
  readonly providers: Provider[] = [];
  readonly plugins: Plugin[] = [];
  services = new Map<ServiceTypeName, Service[]>();
  models = new Map<string, ModelHandler[]>();
  
  constructor(opts: {
    character: Character;
    adapter?: IDatabaseAdapter;
    plugins?: Plugin[];
    settings?: RuntimeSettings;
  }) {
    this.agentId = opts.character.id || stringToUuid(opts.character.name);
    this.character = opts.character;
    
    if (opts.adapter) {
      this.registerDatabaseAdapter(opts.adapter);
    }
    
    this.characterPlugins = opts.plugins || [];
    this.settings = opts.settings || {};
    
    this.logger = createLogger({
      namespace: this.character.name
    });
  }
  
  async initialize(): Promise<void> {
    this.logger.info('Initializing AgentRuntime...');
    
    // 1. Connect to database
    await this.adapter.init();
    
    // 2. Resolve and load plugins
    await this.loadPlugins();
    
    // 3. Start services
    await this.startServices();
    
    // 4. Initialize providers
    await this.initializeProviders();
    
    // 5. Set agent status
    await this.updateAgentStatus(AgentStatus.ACTIVE);
    
    this.isInitialized = true;
    this.logger.info('AgentRuntime initialized successfully');
  }
}

Component Management

How the runtime manages different component types:

class AgentRuntime {
  // Action registration and management
  registerAction(action: Action): void {
    if (this.actions.find(a => a.name === action.name)) {
      throw new Error(`Action ${action.name} already registered`);
    }
    
    this.actions.push(action);
    this.logger.debug(`Registered action: ${action.name}`);
  }
  
  // Provider registration and management
  registerProvider(provider: Provider): void {
    if (this.providers.find(p => p.name === provider.name)) {
      throw new Error(`Provider ${provider.name} already registered`);
    }
    
    this.providers.push(provider);
    this.logger.debug(`Registered provider: ${provider.name}`);
  }
  
  // Service registration and lifecycle
  async registerService(ServiceClass: typeof Service): Promise<Service> {
    const serviceName = ServiceClass.serviceType;
    
    // Check if already registered
    if (this.services.has(serviceName)) {
      return this.services.get(serviceName)[0];
    }
    
    // Create and start service
    const service = new ServiceClass(this);
    await service.start();
    
    this.services.set(serviceName, [service]);
    this.logger.info(`Service ${serviceName} started`);
    
    return service;
  }
  
  // Get a registered service
  getService<T extends Service>(name: ServiceTypeName): T | null {
    const services = this.services.get(name);
    return services?.[0] as T || null;
  }
}

Plugin Integration

Plugin Loading Process

The complete plugin loading lifecycle:

class AgentRuntime {
  private async loadPlugins(): Promise<void> {
    // 1. Resolve all plugin dependencies
    const pluginsToLoad = await this.resolvePluginDependencies(this.characterPlugins);
    
    // 2. Sort plugins by dependency order
    const sortedPlugins = this.topologicalSort(pluginsToLoad);
    
    // 3. Load each plugin in order
    for (const plugin of sortedPlugins) {
      await this.registerPlugin(plugin);
    }
  }
  
  private async resolvePluginDependencies(plugins: Plugin[]): Promise<Plugin[]> {
    const resolved = new Map<string, Plugin>();
    const queue = [...plugins];
    
    while (queue.length > 0) {
      const plugin = queue.shift()!;
      
      if (resolved.has(plugin.name)) continue;
      resolved.set(plugin.name, plugin);
      
      // Add dependencies to queue
      if (plugin.dependencies) {
        for (const depName of plugin.dependencies) {
          const dep = this.allAvailablePlugins.get(depName);
          if (dep && !resolved.has(depName)) {
            queue.push(dep);
          }
        }
      }
    }
    
    return Array.from(resolved.values());
  }
  
  async registerPlugin(plugin: Plugin): Promise<void> {
    this.logger.info(`Registering plugin: ${plugin.name}`);
    
    // 1. Call plugin's init function
    if (plugin.init) {
      await plugin.init(plugin.config || {}, this);
    }
    
    // 2. Register services
    if (plugin.services) {
      for (const ServiceClass of plugin.services) {
        await this.registerService(ServiceClass);
      }
    }
    
    // 3. Register actions
    if (plugin.actions) {
      for (const action of plugin.actions) {
        this.registerAction(action);
      }
    }
    
    // 4. Register providers
    if (plugin.providers) {
      for (const provider of plugin.providers) {
        this.registerProvider(provider);
      }
    }
    
    // 5. Register evaluators
    if (plugin.evaluators) {
      for (const evaluator of plugin.evaluators) {
        this.registerEvaluator(evaluator);
      }
    }
    
    // 6. Register models
    if (plugin.models) {
      for (const [type, handler] of Object.entries(plugin.models)) {
        this.registerModel(type, handler, plugin.name, plugin.priority);
      }
    }
    
    this.plugins.push(plugin);
    this.logger.info(`Plugin ${plugin.name} registered successfully`);
  }
}

Plugin Lifecycle Hooks

Plugins can hook into various lifecycle events:

interface Plugin {
  // Initialization - called when plugin is loaded
  init?: (config: any, runtime: IAgentRuntime) => Promise<void>;
  
  // Start - called when runtime starts
  start?: (runtime: IAgentRuntime) => Promise<void>;
  
  // Stop - called when runtime stops
  stop?: (runtime: IAgentRuntime) => Promise<void>;
  
  // Message hooks
  beforeMessage?: (message: Memory, runtime: IAgentRuntime) => Promise<Memory>;
  afterMessage?: (message: Memory, response: Memory, runtime: IAgentRuntime) => Promise<void>;
  
  // Action hooks
  beforeAction?: (action: Action, message: Memory, runtime: IAgentRuntime) => Promise<boolean>;
  afterAction?: (action: Action, result: any, runtime: IAgentRuntime) => Promise<void>;
}

// Example plugin with lifecycle hooks
const lifecyclePlugin: Plugin = {
  name: 'lifecycle-example',
  
  async init(config, runtime) {
    console.log('Plugin initializing...');
    // Setup plugin resources
  },
  
  async start(runtime) {
    console.log('Plugin starting...');
    // Start background tasks
  },
  
  async stop(runtime) {
    console.log('Plugin stopping...');
    // Cleanup resources
  },
  
  async beforeMessage(message, runtime) {
    // Modify or validate message before processing
    return {
      ...message,
      metadata: {
        ...message.metadata,
        preprocessed: true
      }
    };
  },
  
  async afterMessage(message, response, runtime) {
    // Log, analyze, or store conversation
    await runtime.createMemory({
      content: {
        text: `Processed: ${message.content.text}`,
        metadata: { type: 'conversation_log' }
      }
    });
  }
};

Component Orchestration

Action Selection and Execution

How the runtime selects and executes actions:

class ActionOrchestrator {
  async selectAction(
    runtime: IAgentRuntime,
    message: Memory,
    state: State
  ): Promise<Action | null> {
    // 1. Get all available actions
    const availableActions = runtime.actions;
    
    // 2. Validate which actions can handle this message
    const validActions = await Promise.all(
      availableActions.map(async action => {
        try {
          const isValid = await action.validate?.(runtime, message, state);
          return isValid ? action : null;
        } catch (error) {
          runtime.logger.error(`Validation error for ${action.name}:`, error);
          return null;
        }
      })
    );
    
    const candidates = validActions.filter(Boolean);
    
    if (candidates.length === 0) return null;
    
    // 3. Use LLM to select best action
    const selectedAction = await this.selectWithLLM(
      runtime,
      candidates,
      message,
      state
    );
    
    return selectedAction;
  }
  
  async executeAction(
    runtime: IAgentRuntime,
    action: Action,
    message: Memory,
    state: State
  ): Promise<ActionResult> {
    const startTime = Date.now();
    
    try {
      // Pre-execution hook
      if (runtime.currentPlugin?.beforeAction) {
        const shouldContinue = await runtime.currentPlugin.beforeAction(
          action,
          message,
          runtime
        );
        if (!shouldContinue) {
          return { success: false, reason: 'Blocked by plugin' };
        }
      }
      
      // Execute action
      const result = await action.handler(
        runtime,
        message,
        state,
        {},
        (response) => {
          // Callback for streaming responses
          runtime.emit('action:response', { action: action.name, response });
        }
      );
      
      // Post-execution hook
      if (runtime.currentPlugin?.afterAction) {
        await runtime.currentPlugin.afterAction(action, result, runtime);
      }
      
      // Log execution
      runtime.logger.info(`Action ${action.name} executed in ${Date.now() - startTime}ms`);
      
      return {
        success: true,
        data: result,
        executionTime: Date.now() - startTime
      };
    } catch (error) {
      runtime.logger.error(`Action ${action.name} failed:`, error);
      return {
        success: false,
        error: error.message,
        executionTime: Date.now() - startTime
      };
    }
  }
}

Provider Composition

How providers contribute to state:

class ProviderOrchestrator {
  async composeState(
    runtime: IAgentRuntime,
    message: Memory
  ): Promise<State> {
    const state: State = {
      messages: [],
      facts: [],
      providers: {},
      context: '',
      metadata: {
        roomId: message.roomId,
        entityId: message.entityId,
        timestamp: Date.now(),
        tokenCount: 0
      }
    };
    
    // 1. Get recent messages
    state.messages = await runtime.getMemories({
      roomId: message.roomId,
      count: runtime.conversationLength
    });
    
    // 2. Run all providers in parallel
    const providerPromises = runtime.providers.map(async provider => {
      try {
        const result = await provider.get(runtime, message, state);
        return { name: provider.name, result };
      } catch (error) {
        runtime.logger.error(`Provider ${provider.name} failed:`, error);
        return null;
      }
    });
    
    const providerResults = await Promise.all(providerPromises);
    
    // 3. Merge provider data into state
    for (const item of providerResults) {
      if (!item) continue;
      
      state.providers[item.name] = {
        text: item.result.text || '',
        data: item.result.data || {}
      };
      
      // Add to context
      if (item.result.text) {
        state.context += `\n[${item.name.toUpperCase()}]\n${item.result.text}\n`;
      }
    }
    
    // 4. Calculate token count
    state.metadata.tokenCount = this.estimateTokens(state.context);
    
    return state;
  }
}

Evaluator Execution

Post-processing with evaluators:

class EvaluatorOrchestrator {
  async runEvaluators(
    runtime: IAgentRuntime,
    message: Memory,
    response: Memory,
    state: State
  ): Promise<EvaluationResults> {
    const results: EvaluationResults = {};
    
    // Filter evaluators that should run
    const evaluatorsToRun = runtime.evaluators.filter(evaluator => {
      // Always run if marked as alwaysRun
      if (evaluator.alwaysRun) return true;
      
      // Run if agent responded
      if (response) return true;
      
      // Check custom conditions
      return evaluator.shouldRun?.(message, state);
    });
    
    // Run evaluators in parallel
    const evaluationPromises = evaluatorsToRun.map(async evaluator => {
      try {
        const result = await evaluator.handler(
          runtime,
          message,
          state,
          {},
          () => {},  // Callback
          [response]  // Response array
        );
        
        return { name: evaluator.name, result };
      } catch (error) {
        runtime.logger.error(`Evaluator ${evaluator.name} failed:`, error);
        return { name: evaluator.name, error };
      }
    });
    
    const evaluations = await Promise.all(evaluationPromises);
    
    // Process results
    for (const evaluation of evaluations) {
      if (evaluation.error) {
        results[evaluation.name] = { success: false, error: evaluation.error };
      } else {
        results[evaluation.name] = { success: true, data: evaluation.result };
      }
    }
    
    // Store evaluation results
    await this.storeEvaluations(runtime, message, response, results);
    
    return results;
  }
}

Service Management

Service Registration

Services are long-running components:

abstract class Service {
  static serviceType: ServiceTypeName;
  status: ServiceStatus = ServiceStatus.STOPPED;
  runtime: IAgentRuntime;
  
  constructor(runtime: IAgentRuntime) {
    this.runtime = runtime;
  }
  
  abstract start(): Promise<void>;
  abstract stop(): Promise<void>;
}

// Example service implementation
class WebSocketService extends Service {
  static serviceType = 'websocket' as ServiceTypeName;
  private ws: WebSocket | null = null;
  
  async start(): Promise<void> {
    this.ws = new WebSocket(this.runtime.getSetting('WS_URL'));
    
    this.ws.on('open', () => {
      this.status = ServiceStatus.RUNNING;
      this.runtime.logger.info('WebSocket connected');
    });
    
    this.ws.on('message', async (data) => {
      await this.handleMessage(data);
    });
    
    this.ws.on('error', (error) => {
      this.runtime.logger.error('WebSocket error:', error);
      this.status = ServiceStatus.ERROR;
    });
  }
  
  async stop(): Promise<void> {
    if (this.ws) {
      this.ws.close();
      this.ws = null;
    }
    this.status = ServiceStatus.STOPPED;
  }
  
  private async handleMessage(data: any) {
    // Process incoming websocket messages
    const message = JSON.parse(data);
    await this.runtime.processMessage(message);
  }
}

Service Lifecycle

Managing service dependencies and lifecycle:

class ServiceManager {
  private services = new Map<ServiceTypeName, Service>();
  private startOrder: ServiceTypeName[] = [];
  
  async startServices(runtime: IAgentRuntime): Promise<void> {
    // Determine start order based on dependencies
    this.startOrder = this.resolveServiceDependencies();
    
    for (const serviceName of this.startOrder) {
      const ServiceClass = this.getServiceClass(serviceName);
      if (!ServiceClass) continue;
      
      try {
        const service = new ServiceClass(runtime);
        await service.start();
        this.services.set(serviceName, service);
        runtime.logger.info(`Service ${serviceName} started`);
      } catch (error) {
        runtime.logger.error(`Failed to start service ${serviceName}:`, error);
        // Decide whether to continue or abort
        if (this.isRequiredService(serviceName)) {
          throw error;
        }
      }
    }
  }
  
  async stopServices(runtime: IAgentRuntime): Promise<void> {
    // Stop in reverse order
    const stopOrder = [...this.startOrder].reverse();
    
    for (const serviceName of stopOrder) {
      const service = this.services.get(serviceName);
      if (!service) continue;
      
      try {
        await service.stop();
        runtime.logger.info(`Service ${serviceName} stopped`);
      } catch (error) {
        runtime.logger.error(`Error stopping service ${serviceName}:`, error);
      }
    }
    
    this.services.clear();
  }
  
  async restartService(
    runtime: IAgentRuntime,
    serviceName: ServiceTypeName
  ): Promise<void> {
    const service = this.services.get(serviceName);
    
    if (service) {
      await service.stop();
    }
    
    const ServiceClass = this.getServiceClass(serviceName);
    const newService = new ServiceClass(runtime);
    await newService.start();
    
    this.services.set(serviceName, newService);
  }
}

Multi-agent Systems

Agent Coordination

Managing multiple agents in a system:

class MultiAgentCoordinator {
  private agents = new Map<UUID, IAgentRuntime>();
  private messageQueue = new Map<UUID, Memory[]>();
  
  async registerAgent(agent: IAgentRuntime): Promise<void> {
    this.agents.set(agent.agentId, agent);
    this.messageQueue.set(agent.agentId, []);
    
    // Setup inter-agent communication
    agent.on('message:send', async (data) => {
      await this.routeMessage(data.from, data.to, data.message);
    });
  }
  
  async routeMessage(
    fromAgent: UUID,
    toAgent: UUID,
    message: Memory
  ): Promise<void> {
    const targetAgent = this.agents.get(toAgent);
    
    if (!targetAgent) {
      // Queue message for offline agent
      this.messageQueue.get(toAgent)?.push(message);
      return;
    }
    
    // Deliver message
    await targetAgent.processMessage({
      ...message,
      metadata: {
        ...message.metadata,
        fromAgent,
        interAgent: true
      }
    });
  }
  
  async broadcastMessage(
    fromAgent: UUID,
    message: Memory
  ): Promise<void> {
    const promises = Array.from(this.agents.entries())
      .filter(([id]) => id !== fromAgent)
      .map(([id, agent]) => agent.processMessage(message));
    
    await Promise.all(promises);
  }
}

Agent Hierarchies

Parent-child agent relationships:

interface AgentHierarchy {
  parent?: UUID;
  children: UUID[];
  permissions: {
    canCreateChildren: boolean;
    canControlChildren: boolean;
    canAccessParentMemory: boolean;
  };
}

class HierarchicalAgentSystem {
  private hierarchy = new Map<UUID, AgentHierarchy>();
  
  async createChildAgent(
    parentRuntime: IAgentRuntime,
    childCharacter: Character
  ): Promise<IAgentRuntime> {
    // Inherit settings from parent
    const childCharacter: Character = {
      ...childCharacter,
      settings: {
        ...parentRuntime.character.settings,
        ...childCharacter.settings
      },
      // Inherit some plugins
      plugins: [
        ...parentRuntime.character.plugins.filter(p => this.isInheritable(p)),
        ...childCharacter.plugins
      ]
    };
    
    // Create child runtime
    const childRuntime = new AgentRuntime({
      character: childCharacter,
      adapter: parentRuntime.adapter,  // Share database
      settings: parentRuntime.settings
    });
    
    await childRuntime.initialize();
    
    // Update hierarchy
    this.hierarchy.set(childRuntime.agentId, {
      parent: parentRuntime.agentId,
      children: [],
      permissions: {
        canCreateChildren: false,
        canControlChildren: false,
        canAccessParentMemory: true
      }
    });
    
    // Update parent's children list
    const parentHierarchy = this.hierarchy.get(parentRuntime.agentId);
    if (parentHierarchy) {
      parentHierarchy.children.push(childRuntime.agentId);
    }
    
    return childRuntime;
  }
  
  async delegateTask(
    parentRuntime: IAgentRuntime,
    childId: UUID,
    task: Task
  ): Promise<TaskResult> {
    const childRuntime = this.agents.get(childId);
    
    if (!childRuntime) {
      throw new Error(`Child agent ${childId} not found`);
    }
    
    // Check permissions
    const hierarchy = this.hierarchy.get(parentRuntime.agentId);
    if (!hierarchy?.children.includes(childId)) {
      throw new Error('No authority over this agent');
    }
    
    // Delegate task
    return await childRuntime.executeTask(task);
  }
}

Production Considerations

Initialization Strategies

Different approaches for production deployment:

// Lazy initialization - start minimal, load as needed
class LazyRuntime extends AgentRuntime {
  private loadedPlugins = new Set<string>();
  
  async initialize(): Promise<void> {
    // Load only core plugins
    await this.loadCorePlugins();
    this.isInitialized = true;
  }
  
  async loadPlugin(pluginName: string): Promise<void> {
    if (this.loadedPlugins.has(pluginName)) return;
    
    const plugin = await this.fetchPlugin(pluginName);
    await this.registerPlugin(plugin);
    this.loadedPlugins.add(pluginName);
  }
  
  // Load plugin on first use
  async getAction(name: string): Promise<Action | null> {
    let action = this.actions.find(a => a.name === name);
    
    if (!action) {
      // Try to load plugin that provides this action
      const pluginName = this.findPluginForAction(name);
      if (pluginName) {
        await this.loadPlugin(pluginName);
        action = this.actions.find(a => a.name === name);
      }
    }
    
    return action;
  }
}

// Eager initialization - load everything upfront
class EagerRuntime extends AgentRuntime {
  async initialize(): Promise<void> {
    // Load all plugins immediately
    await this.loadAllPlugins();
    
    // Pre-warm caches
    await this.prewarmCaches();
    
    // Pre-compile templates
    await this.compileTemplates();
    
    this.isInitialized = true;
  }
}

Error Recovery

Implementing robust error handling:

class ResilientRuntime extends AgentRuntime {
  private errorCount = new Map<string, number>();
  private circuitBreakers = new Map<string, CircuitBreaker>();
  
  async processMessageWithRecovery(message: Memory): Promise<void> {
    const maxRetries = 3;
    let lastError: Error | null = null;
    
    for (let attempt = 1; attempt <= maxRetries; attempt++) {
      try {
        // Check circuit breaker
        const breaker = this.circuitBreakers.get('message_processing');
        if (breaker?.isOpen()) {
          throw new Error('Circuit breaker is open');
        }
        
        await this.processMessage(message);
        
        // Reset error count on success
        this.errorCount.set('message_processing', 0);
        return;
        
      } catch (error) {
        lastError = error;
        this.logger.error(`Attempt ${attempt} failed:`, error);
        
        // Update error count
        const count = (this.errorCount.get('message_processing') || 0) + 1;
        this.errorCount.set('message_processing', count);
        
        // Trip circuit breaker if too many errors
        if (count > 10) {
          this.circuitBreakers.get('message_processing')?.trip();
        }
        
        // Exponential backoff
        if (attempt < maxRetries) {
          await this.sleep(Math.pow(2, attempt) * 1000);
        }
      }
    }
    
    // All retries failed
    await this.handleCriticalError(lastError!, message);
  }
  
  private async handleCriticalError(
    error: Error,
    message: Memory
  ): Promise<void> {
    // Log to error tracking service
    await this.logToErrorService(error, {
      message,
      agentId: this.agentId,
      timestamp: Date.now()
    });
    
    // Send fallback response
    await this.sendFallbackResponse(message);
    
    // Notify administrators
    await this.notifyAdmins(error);
  }
}

Monitoring and Metrics

Production monitoring implementation:

interface RuntimeMetrics {
  messagesProcessed: number;
  averageResponseTime: number;
  errorRate: number;
  memoryUsage: number;
  activeServices: number;
  pluginPerformance: Map<string, PluginMetrics>;
}

class MonitoredRuntime extends AgentRuntime {
  private metrics: RuntimeMetrics = {
    messagesProcessed: 0,
    averageResponseTime: 0,
    errorRate: 0,
    memoryUsage: 0,
    activeServices: 0,
    pluginPerformance: new Map()
  };
  
  async processMessage(message: Memory): Promise<void> {
    const startTime = Date.now();
    
    try {
      await super.processMessage(message);
      
      // Update metrics
      this.metrics.messagesProcessed++;
      this.updateAverageResponseTime(Date.now() - startTime);
      
    } catch (error) {
      this.metrics.errorRate = this.calculateErrorRate();
      throw error;
    } finally {
      // Collect memory usage
      this.metrics.memoryUsage = process.memoryUsage().heapUsed;
      
      // Send metrics
      await this.sendMetrics();
    }
  }
  
  private async sendMetrics(): Promise<void> {
    // Send to monitoring service (e.g., Prometheus, DataDog)
    await fetch(process.env.METRICS_ENDPOINT!, {
      method: 'POST',
      body: JSON.stringify({
        agentId: this.agentId,
        timestamp: Date.now(),
        metrics: this.metrics
      })
    });
  }
  
  // Health check endpoint
  async getHealth(): Promise<HealthStatus> {
    return {
      status: this.isHealthy() ? 'healthy' : 'unhealthy',
      uptime: process.uptime(),
      metrics: this.metrics,
      services: Array.from(this.services.entries()).map(([name, services]) => ({
        name,
        status: services[0]?.status || 'unknown'
      }))
    };
  }
}

Scaling Strategies

Horizontal scaling approaches:

// Load balancer for multiple agent instances
class AgentLoadBalancer {
  private instances: IAgentRuntime[] = [];
  private currentIndex = 0;
  
  async addInstance(character: Character): Promise<void> {
    const runtime = new AgentRuntime({ character });
    await runtime.initialize();
    this.instances.push(runtime);
  }
  
  // Round-robin load balancing
  getNextInstance(): IAgentRuntime {
    const instance = this.instances[this.currentIndex];
    this.currentIndex = (this.currentIndex + 1) % this.instances.length;
    return instance;
  }
  
  // Load-based routing
  getLeastLoadedInstance(): IAgentRuntime {
    return this.instances.reduce((least, current) => {
      const leastLoad = least.getMetrics().activeRequests;
      const currentLoad = current.getMetrics().activeRequests;
      return currentLoad < leastLoad ? current : least;
    });
  }
  
  async scaleUp(): Promise<void> {
    const baseCharacter = this.instances[0].character;
    await this.addInstance(baseCharacter);
  }
  
  async scaleDown(): Promise<void> {
    if (this.instances.length <= 1) return;
    
    const instance = this.instances.pop();
    await instance?.stop();
  }
}

Deployment Patterns

Single Agent Deployment

Basic deployment for a single agent:

// server.ts
import { AgentRuntime } from '@elizaos/core';
import { PostgresDatabaseAdapter } from '@elizaos/plugin-sql';
import { character } from './character';

async function startAgent() {
  // Create database adapter
  const adapter = new PostgresDatabaseAdapter({
    connectionString: process.env.DATABASE_URL
  });
  
  // Create runtime
  const runtime = new AgentRuntime({
    character,
    adapter,
    settings: {
      logLevel: process.env.LOG_LEVEL || 'info'
    }
  });
  
  // Initialize
  await runtime.initialize();
  
  // Start HTTP server for API
  const app = express();
  
  app.post('/message', async (req, res) => {
    try {
      const response = await runtime.processMessage(req.body);
      res.json(response);
    } catch (error) {
      res.status(500).json({ error: error.message });
    }
  });
  
  app.get('/health', async (req, res) => {
    const health = await runtime.getHealth();
    res.json(health);
  });
  
  app.listen(process.env.PORT || 3000);
  
  // Graceful shutdown
  process.on('SIGTERM', async () => {
    await runtime.stop();
    process.exit(0);
  });
}

startAgent().catch(console.error);

Agent Swarm Deployment

Managing multiple agents:

class AgentSwarm {
  private agents = new Map<UUID, IAgentRuntime>();
  private coordinator: MultiAgentCoordinator;
  
  async deploySwarm(characters: Character[]): Promise<void> {
    // Shared database for all agents
    const adapter = new PostgresDatabaseAdapter({
      connectionString: process.env.DATABASE_URL
    });
    
    // Deploy each agent
    for (const character of characters) {
      const runtime = new AgentRuntime({
        character,
        adapter,
        settings: this.getSwarmSettings()
      });
      
      await runtime.initialize();
      this.agents.set(runtime.agentId, runtime);
      
      // Register with coordinator
      await this.coordinator.registerAgent(runtime);
    }
    
    // Setup swarm communication
    await this.setupSwarmCommunication();
  }
  
  private async setupSwarmCommunication(): Promise<void> {
    // Create message bus for inter-agent communication
    const messageBus = new EventEmitter();
    
    for (const [id, agent] of this.agents) {
      // Subscribe to agent's outgoing messages
      agent.on('message:external', (data) => {
        messageBus.emit('swarm:message', {
          from: id,
          ...data
        });
      });
      
      // Route swarm messages to agent
      messageBus.on('swarm:message', async (data) => {
        if (data.to === id || data.broadcast) {
          await agent.processMessage(data.message);
        }
      });
    }
  }
}

Edge Deployment

Optimized for resource-constrained environments:

class EdgeRuntime extends AgentRuntime {
  constructor(opts: EdgeRuntimeOptions) {
    super({
      ...opts,
      // Use lightweight alternatives
      adapter: new SQLiteAdapter({
        path: './agent.db'
      }),
      settings: {
        ...opts.settings,
        // Reduce resource usage
        maxMemorySize: 100,  // Smaller memory buffer
        conversationLength: 10,  // Shorter context
        cacheSize: 50  // Smaller cache
      }
    });
  }
  
  async initialize(): Promise<void> {
    // Load only essential plugins
    const essentialPlugins = this.characterPlugins.filter(
      p => this.isEssential(p.name)
    );
    
    this.characterPlugins = essentialPlugins;
    await super.initialize();
    
    // Enable offline mode
    await this.enableOfflineMode();
  }
  
  private async enableOfflineMode(): Promise<void> {
    // Cache common responses
    await this.cacheCommonResponses();
    
    // Use local models if available
    if (await this.hasLocalModel()) {
      this.registerModel('local', this.localModelHandler);
    }
    
    // Setup sync when online
    this.setupSyncWhenOnline();
  }
  
  private setupSyncWhenOnline(): void {
    setInterval(async () => {
      if (await this.isOnline()) {
        await this.syncWithCloud();
      }
    }, 60000);  // Check every minute
  }
}

Best Practices

Initialize once: Create the runtime once and reuse it for all operations
Handle lifecycle properly: Always call stop() for graceful shutdown
Monitor health: Implement health checks and metrics
Use dependency injection: Pass runtime to components rather than importing globally
Implement circuit breakers: Prevent cascading failures
Log strategically: Log important events but avoid logging sensitive data
Cache appropriately: Cache expensive operations but manage memory
Version your deployments: Track which version of agents are running
Test in production-like environments: Use similar resources and configurations
Plan for failure: Implement fallbacks and recovery strategies

Troubleshooting

Common Runtime Issues

Agent Not Responding

async function debugUnresponsiveAgent(runtime: IAgentRuntime) {
  // Check initialization
  console.log('Is initialized:', runtime.isInitialized);
  
  // Check services
  const services = runtime.getServices();
  for (const [name, service] of services) {
    console.log(`Service ${name}: ${service.status}`);
  }
  
  // Check action availability
  console.log('Available actions:', runtime.actions.map(a => a.name));
  
  // Check database connection
  try {
    await runtime.adapter.ping();
    console.log('Database: Connected');
  } catch (error) {
    console.log('Database: Disconnected', error);
  }
  
  // Check memory usage
  const usage = process.memoryUsage();
  console.log('Memory usage:', {
    rss: `${Math.round(usage.rss / 1024 / 1024)}MB`,
    heap: `${Math.round(usage.heapUsed / 1024 / 1024)}MB`
  });
}

Plugin Loading Failures

async function debugPluginLoading(runtime: IAgentRuntime, pluginName: string) {
  try {
    // Check if plugin exists
    const plugin = runtime.allAvailablePlugins.get(pluginName);
    if (!plugin) {
      console.log(`Plugin ${pluginName} not found in available plugins`);
      return;
    }
    
    // Check dependencies
    if (plugin.dependencies) {
      for (const dep of plugin.dependencies) {
        const depPlugin = runtime.plugins.find(p => p.name === dep);
        if (!depPlugin) {
          console.log(`Missing dependency: ${dep}`);
        }
      }
    }
    
    // Try loading manually
    await runtime.registerPlugin(plugin);
    console.log(`Plugin ${pluginName} loaded successfully`);
    
  } catch (error) {
    console.log(`Plugin loading error:`, error);
  }
}

Guide: Customize an Agent

Character Interface

Define your agent’s character configuration

Personality & Behavior

Craft unique agent personalities

Memory & State

Understand agent memory and context

Plugin Development

Extend runtime capabilities with plugins

​Agent Lifecycle Overview

​Character to Agent Transformation

​Loading Characters

​Character Validation

​Agent Instantiation

​Runtime Architecture

​AgentRuntime Core

​Component Management

​Plugin Integration

​Plugin Loading Process

​Plugin Lifecycle Hooks

​Component Orchestration

​Action Selection and Execution

​Provider Composition

​Evaluator Execution

​Service Management

​Service Registration

​Service Lifecycle

​Multi-agent Systems

​Agent Coordination

​Agent Hierarchies

​Production Considerations

​Initialization Strategies

​Error Recovery

​Monitoring and Metrics

​Scaling Strategies

​Deployment Patterns

​Single Agent Deployment

​Agent Swarm Deployment

​Edge Deployment

​Best Practices

​Troubleshooting

​Common Runtime Issues

​Agent Not Responding

​Plugin Loading Failures

​See Also

Character Interface

Personality & Behavior

Memory & State

Plugin Development

Agent Lifecycle Overview

Character to Agent Transformation

Loading Characters

Character Validation

Agent Instantiation

Runtime Architecture

AgentRuntime Core

Component Management

Plugin Integration

Plugin Loading Process

Plugin Lifecycle Hooks

Component Orchestration

Action Selection and Execution

Provider Composition

Evaluator Execution

Service Management

Service Registration

Service Lifecycle

Multi-agent Systems

Agent Coordination

Agent Hierarchies

Production Considerations

Initialization Strategies

Error Recovery

Monitoring and Metrics

Scaling Strategies

Deployment Patterns

Single Agent Deployment

Agent Swarm Deployment

Edge Deployment

Best Practices

Troubleshooting

Common Runtime Issues

Agent Not Responding

Plugin Loading Failures

See Also