Letta Code SDK Overview

Fresh

Source: Letta Code SDK

What is the Letta Code SDK?

The Letta Code SDK provides a programmatic interface to Letta Code, enabling you to build applications that leverage Letta Code's advanced coding agent harness with persistent memory.

Installation

npm install @letta-ai/letta-code-sdk

Quick Start

One-Shot Query

Simple queries that return an immediate response without persistence:

import { prompt } from '@letta-ai/letta-code-sdk';

const result = await prompt('What does the main function do?');
console.log(result);

Persistent Agent

Multi-turn conversations with memory across sessions:

import { createAgent, resumeSession } from '@letta-ai/letta-code-sdk';

// Create a new agent with memory
const session = await createAgent({
  memoryBlocks: [
    { label: 'persona', value: 'You are a senior TypeScript engineer.' },
    { label: 'human', value: 'Prefers functional patterns and strict types.' }
  ]
});

// Send messages
const response = await session.send('Review the auth module for security issues');
console.log(response);

// Close the session
await session.close();

// Later: resume with full memory context
const resumed = await resumeSession(session.agentId);
const followUp = await resumed.send('Did you find any issues last time?');

Streaming Responses

const session = await createAgent();

for await (const chunk of session.stream('Explain the architecture')) {
  process.stdout.write(chunk);
}

await session.close();

Key Concepts

Concept	Description
Agent	Persistent entity with memory that survives across sessions
Conversation	A message thread within an agent; multiple can coexist
Session	A single execution/connection to an agent
Default Conversation	Auto-created with each agent; accessed via resumeSession(agentId)

Session Auto-Close

With TypeScript 5.2+, sessions auto-close using the await using syntax:

await using session = await createAgent();
await session.send('Hello!');
// Session automatically closes when scope exits

For older TypeScript versions, always call session.close() manually.

Next Steps

• API Reference - Complete function signatures and types
• Migration Guide - Migrating from Claude Agent SDK
• Agents - Deep dive into agent configuration