Letta Code SDK migration guide

The Claude Agent SDK is query-based and does not expose a persistent agent entity; state lives in a session/thread resumed by session_id. Letta Code SDK is agent-based with persistent memory, and also supports multiple conversation threads per agent. The closest mental model depends on which Claude SDK interface you’re using.

Claude Agent SDK V2 (preview)

V2 uses createSession / resumeSession with an explicit send() / stream() cycle per turn. This maps closely to Letta Code SDK.

High-level mapping (V2)

Claude Agent SDK V2	Letta Code SDK
unstable_v2_prompt(...)	prompt(...)
unstable_v2_createSession(...)	createSession(...)
unstable_v2_resumeSession(session_id)	resumeSession(conversationId)
session.send(...)	session.send(...)
session.stream()	session.stream()

Notes

• Claude session_id corresponds to Letta conversationId.
• Letta sessions are anchored to a persistent agent; Claude sessions are ephemeral unless you store the session ID.
• If you want stateless behavior, use prompt(...) or create a fresh agent per run.

Claude Agent SDK V1 (query-based)

V1 streams results from a single query(...) async generator. In Letta Code SDK, use prompt(...) for one-shots or createSession(...).send() + stream() for multi-turn flows.

High-level mapping (V1)

Claude Agent SDK V1	Letta Code SDK
query({ prompt, options })	prompt(message) or createSession(...).send()

Key differences

Feature	Claude Agent SDK	Letta Code SDK
Persistence model	Session-based (ephemeral)	Agent-based (persistent)
Memory	Session state only	Persistent memory blocks
Model support	Claude only	Claude, GPT, Gemini, local models
Multiple conversations	One per session	Multiple per agent

Example migration

Before (Claude Agent SDK V2)

import { unstable_v2_createSession, unstable_v2_resumeSession } from "@anthropic-ai/claude-agent";

// Create new session
const session = await unstable_v2_createSession({
  systemPrompt: "You are a helpful assistant.",
});

// Send message
await session.send("Hello!");
for await (const msg of session.stream()) {
  console.log(msg);
}

// Resume later
const resumed = await unstable_v2_resumeSession(session.sessionId);

After (Letta Code SDK)

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

// Create new agent (persistent)
const agentId = await createAgent();
const session = createSession(agentId, {
  systemPrompt: "You are a helpful assistant.",
});

// Send message
await session.send("Hello!");
for await (const msg of session.stream()) {
  console.log(msg);
}

// Resume later (agent persists with memory)
const resumed = resumeSession(agentId);