> ## Documentation Index
> Fetch the complete documentation index at: https://docs.agentium.in/llms.txt
> Use this file to discover all available pages before exploring further.

# In-Memory Storage

> InMemoryStorage driver—zero dependencies, no persistence. Default for agents when no storage is configured.

# In-Memory Storage

**InMemoryStorage** is the simplest storage driver. It keeps all data in a JavaScript `Map`—no external dependencies, no disk I/O. Data is **lost when the process restarts**. Use it for development, testing, or ephemeral workloads.

***

## When to Use

<CardGroup cols={2}>
  <Card title="Development" icon="code">
    Fast iteration. No database setup required.
  </Card>

  <Card title="Testing" icon="flask">
    Isolated tests. No shared state between runs.
  </Card>

  <Card title="Demos" icon="presentation">
    Quick prototypes. No infrastructure needed.
  </Card>

  <Card title="Not for Production" icon="warning">
    Data is lost on restart. Use Sqlite, Postgres, or MongoDB for persistence.
  </Card>
</CardGroup>

***

## Installation

No additional packages required. `InMemoryStorage` is included in `@agentium/core`.

***

## Usage

```typescript theme={null}
import { InMemoryStorage } from "@agentium/core";

const storage = new InMemoryStorage();

// No initialize() needed—ready to use immediately
await storage.set("namespace", "key", { foo: "bar" });
const value = await storage.get<{ foo: string }>("namespace", "key");
console.log(value); // { foo: "bar" }

const items = await storage.list("namespace", "k");
console.log(items); // [{ key: "key", value: { foo: "bar" } }]

await storage.delete("namespace", "key");
await storage.close();
```

***

## With Agent

When you don't provide a `storage` option, Agentium defaults to `InMemoryStorage`:

```typescript theme={null}
import { Agent, openai } from "@agentium/core";

// Explicit (same as default)
const agent = new Agent({
  name: "Assistant",
  model: openai("gpt-4o"),
  storage: new InMemoryStorage(),
});

// Implicit—InMemoryStorage is used automatically
const agent2 = new Agent({
  name: "Assistant",
  model: openai("gpt-4o"),
});
```

***

## With Memory

```typescript theme={null}
import { Agent, Memory, InMemoryStorage, openai } from "@agentium/core";

const storage = new InMemoryStorage();
const memory = new Memory({
  storage,
  maxShortTermMessages: 50,
  enableLongTerm: false,
});

const agent = new Agent({
  name: "Assistant",
  model: openai("gpt-4o"),
  memory,
});

// Session data lives in memory until process exits
await agent.run("Hello!", { sessionId: "user-123" });
```

***

## Limitations

| Limitation         | Description                                      |
| ------------------ | ------------------------------------------------ |
| **No persistence** | All data is lost when the Node.js process exits. |
| **Single process** | Not shared across multiple server instances.     |
| **Memory bound**   | Large datasets consume RAM.                      |
| **No backup**      | No built-in snapshot or export.                  |

***

## API Reference

| Method   | Signature                                                     | Description                        |
| -------- | ------------------------------------------------------------- | ---------------------------------- |
| `get`    | `get<T>(namespace, key) => Promise<T \| null>`                | Get value by key.                  |
| `set`    | `set<T>(namespace, key, value) => Promise<void>`              | Store value (JSON-serialized).     |
| `delete` | `delete(namespace, key) => Promise<void>`                     | Remove key.                        |
| `list`   | `list<T>(namespace, prefix?) => Promise<Array<{key, value}>>` | List keys, optionally with prefix. |
| `close`  | `close() => Promise<void>`                                    | Clears the in-memory store.        |