deepagents-memory (JavaScript/TypeScript)

Overview

Short-term (StateBackend): Single thread only
Long-term (StoreBackend): Persists across threads
Hybrid (CompositeBackend): Mix both

Long-term Memory Setup

import { createDeepAgent, CompositeBackend, StateBackend, StoreBackend } from "deepagents";
import { InMemoryStore } from "@langchain/langgraph";

const store = new InMemoryStore();

const agent = await createDeepAgent({
  backend: (config) => new CompositeBackend(
    new StateBackend(config),
    { "/memories/": new StoreBackend(config) }
  ),
  store
});

// /memories/* files persist across threads
// Other files are ephemeral

Code Examples

Example 1: User Preferences Across Sessions

import { createDeepAgent, CompositeBackend, StateBackend, StoreBackend } from "deepagents";
import { InMemoryStore } from "@langchain/langgraph";

const store = new InMemoryStore();

const agent = await createDeepAgent({
  backend: (config) => new CompositeBackend(
    new StateBackend(config),
    { "/memories/": new StoreBackend(config) }
  ),
  store
});

// Thread 1: Save preferences
const config1 = { configurable: { thread_id: "thread-1" } };
await agent.invoke({
  messages: [{
    role: "user",
    content: "Save my coding style to /memories/style.txt: TypeScript, async/await, Jest"
  }]
}, config1);

// Thread 2: Access preferences
const config2 = { configurable: { thread_id: "thread-2" } };
await agent.invoke({
  messages: [{
    role: "user",
    content: "Read my preferences and write a user fetch function"
  }]
}, config2);
// Agent reads /memories/style.txt

Example 2: Using Store Directly in Tools

import { tool } from "langchain";
import { createAgent } from "langchain";
import { InMemoryStore } from "@langchain/langgraph";
import { z } from "zod";

const getUserPreference = tool(
  async ({ key }) => {
    const value = await store.get(["user_prefs"], key);
    return value ? String(value) : "Not found";
  },
  {
    name: "get_user_preference",
    description: "Get a user preference",
    schema: z.object({ key: z.string() }),
  }
);

const saveUserPreference = tool(
  async ({ key, value }) => {
    await store.put(["user_prefs"], key, { value });
    return `Saved ${key}=${value}`;
  },
  {
    name: "save_user_preference",
    description: "Save a user preference",
    schema: z.object({ key: z.string(), value: z.string() }),
  }
);

const store = new InMemoryStore();

const agent = createAgent({
  model: "gpt-4",
  tools: [getUserPreference, saveUserPreference],
  store
});

// First session
await agent.invoke({
  messages: [{ role: "user", content: "Remember I prefer dark mode" }]
});

// Second session
await agent.invoke({
  messages: [{ role: "user", content: "What UI theme do I prefer?" }]
});

Example 3: Project Knowledge Base

const agent = await createDeepAgent({
  backend: (config) => new CompositeBackend(
    new StateBackend(config),
    {
      "/memories/": new StoreBackend(config),
      "/workspace/": new StateBackend(config),
    }
  ),
  store: new InMemoryStore()
});

// Build knowledge
await agent.invoke({
  messages: [{
    role: "user",
    content: "Document the DB schema in /memories/db-schema.md"
  }]
}, { configurable: { thread_id: "thread-1" } });

// Use knowledge later
await agent.invoke({
  messages: [{
    role: "user",
    content: "Write a migration to add email to users"
  }]
}, { configurable: { thread_id: "thread-2" } });

Decision Table

Pattern	Backend	Use Case
All ephemeral	StateBackend	Single-session tasks
All persistent	StoreBackend	Everything remembered
Hybrid	CompositeBackend	/memories/ persistent, rest ephemeral

Boundaries

What Agents CAN Do

✅ Save files to persistent storage
✅ Access persisted files across threads
✅ Mix ephemeral and persistent storage
✅ Use Store namespace/key pattern

What Agents CANNOT Do

❌ Access memory without Store
❌ Persist StateBackend files across threads
❌ Share memory across agents without shared Store

Gotchas

1. StoreBackend Requires Store

// ❌ Missing store
await createDeepAgent({
  backend: (config) => new StoreBackend(config)
});

// ✅ Provide store
await createDeepAgent({
  backend: (config) => new StoreBackend(config),
  store: new InMemoryStore()
});

2. Path Prefix Matters

// ❌ Not persistent (wrong path)
await agent.invoke({
  messages: [{ role: "user", content: "Save to /prefs.txt" }]
});

// ✅ Persistent (matches /memories/ route)
await agent.invoke({
  messages: [{ role: "user", content: "Save to /memories/prefs.txt" }]
});

3. InMemoryStore Not Persistent

// ❌ Lost on restart
const store = new InMemoryStore();

// ✅ Use persistent store for production
import { PostgresStore } from "@langchain/langgraph";
const store = new PostgresStore({ connectionString: "postgresql://..." });

4. Routes Use Longest Prefix Match

const backend = (config) => new CompositeBackend(
  new StateBackend(config),
  {
    "/mem/": new StoreBackend(config),
    "/mem/temp/": new StateBackend(config),  // More specific
  }
);

// /mem/file.txt -> StoreBackend
// /mem/temp/file.txt -> StateBackend (longer match)

Full Documentation

• Long-term Memory
• Backends
• Memory Overview
• LangGraph Store