# Memory class

The `Memory` class provides a robust system for managing conversation history and thread-based message storage in Mastra. It enables persistent storage of conversations, semantic search capabilities, and efficient message retrieval. You must configure a storage provider for conversation history, and if you enable semantic recall you will also need to provide a vector store and embedder.

## Usage example

```typescript
import { Memory } from '@mastra/memory'
import { Agent } from '@mastra/core/agent'

export const agent = new Agent({
  name: 'test-agent',
  instructions: 'You are an agent with memory.',
  model: 'openai/gpt-5.5',
  memory: new Memory({
    options: {
      workingMemory: {
        enabled: true,
      },
    },
  }),
})
```

> **Note:** To enable `workingMemory` on an agent, you’ll need a storage provider configured on your main Mastra instance. See [Mastra class](https://mastra.ai/reference/core/mastra-class) for more information.

## Constructor parameters

**storage** (`MastraCompositeStore`): Storage implementation for persisting memory data. Defaults to \`new DefaultStorage({ config: { url: "file:memory.db" } })\` if not provided.

**vector** (`MastraVector | false`): Vector store for semantic search capabilities. Set to \`false\` to disable vector operations.

**embedder** (`EmbeddingModel<string> | EmbeddingModelV2<string>`): Embedder instance for vector embeddings. Required when semantic recall is enabled.

**options** (`MemoryConfig`): Memory configuration options.

**options.lastMessages** (`number | false`): Number of most recent messages to include in context. Set to \`false\` to disable loading conversation history into context. Use \`Number.MAX\_SAFE\_INTEGER\` to retrieve all messages with no limit. To prevent saving new messages, use the \`readOnly\` option instead.

**options.readOnly** (`boolean`): When true, prevents memory from saving new messages and provides working memory as read-only context (without the updateWorkingMemory tool). Useful for read-only operations like previews, internal routing agents, or sub agents that should reference but not modify memory.

**options.semanticRecall** (`boolean | { topK: number; messageRange: number | { before: number; after: number }; scope?: 'thread' | 'resource' }`): Enable semantic search in message history. Can be a boolean or an object with configuration options. When enabled, requires both vector store and embedder to be configured. Default topK is 4, default messageRange is {before: 1, after: 1}.

**options.workingMemory** (`WorkingMemory`): Configuration for working memory feature. Can be \`{ enabled: boolean; template?: string; schema?: ZodObject\<any> | JSONSchema7; scope?: 'thread' | 'resource' }\` or \`{ enabled: boolean }\` to disable.

**options.observationalMemory** (`boolean | ObservationalMemoryOptions`): Enable Observational Memory for long-context agentic memory. Set to \`true\` for defaults, or pass a config object to customize token budgets, models, and scope. See \[Observational Memory reference]\(/reference/memory/observational-memory) for configuration details.

**options.generateTitle** (`boolean | { model: DynamicArgument<MastraLanguageModel>; instructions?: DynamicArgument<string> }`): Controls automatic thread title generation from the user's first message. Can be a boolean or an object with custom model and instructions.

## Returns

**memory** (`Memory`): A new Memory instance with the specified configuration.

## Extended usage example

```typescript
import { Memory } from '@mastra/memory'
import { Agent } from '@mastra/core/agent'
import { LibSQLStore, LibSQLVector } from '@mastra/libsql'

export const agent = new Agent({
  name: 'test-agent',
  instructions: 'You are an agent with memory.',
  model: 'openai/gpt-5.5',
  memory: new Memory({
    storage: new LibSQLStore({
      id: 'test-agent-storage',
      url: 'file:./working-memory.db',
    }),
    vector: new LibSQLVector({
      id: 'test-agent-vector',
      url: 'file:./vector-memory.db',
    }),
    options: {
      lastMessages: 10,
      semanticRecall: {
        topK: 3,
        messageRange: 2,
        scope: 'resource',
      },
      workingMemory: {
        enabled: true,
      },
      generateTitle: true,
    },
  }),
})
```

## PostgreSQL with index configuration

```typescript
import { Memory } from '@mastra/memory'
import { Agent } from '@mastra/core/agent'
import { ModelRouterEmbeddingModel } from '@mastra/core/llm'
import { PgStore, PgVector } from '@mastra/pg'

export const agent = new Agent({
  name: 'pg-agent',
  instructions: 'You are an agent with optimized PostgreSQL memory.',
  model: 'openai/gpt-5.5',
  memory: new Memory({
    storage: new PgStore({
      id: 'pg-agent-storage',
      connectionString: process.env.DATABASE_URL,
    }),
    vector: new PgVector({
      id: 'pg-agent-vector',
      connectionString: process.env.DATABASE_URL,
    }),
    embedder: new ModelRouterEmbeddingModel('openai/text-embedding-3-small'),
    options: {
      lastMessages: 20,
      semanticRecall: {
        topK: 5,
        messageRange: 3,
        scope: 'resource',
        indexConfig: {
          type: 'hnsw', // Use HNSW for better performance
          metric: 'dotproduct', // Optimal for OpenAI embeddings
          m: 16, // Number of bi-directional links
          efConstruction: 64, // Construction-time candidate list size
        },
      },
      workingMemory: {
        enabled: true,
      },
    },
  }),
})
```

### Related

- [Getting Started with Memory](https://mastra.ai/docs/memory/overview)
- [Semantic Recall](https://mastra.ai/docs/memory/semantic-recall)
- [Working Memory](https://mastra.ai/docs/memory/working-memory)
- [Observational Memory](https://mastra.ai/docs/memory/observational-memory)
- [Memory Processors](https://mastra.ai/docs/memory/memory-processors)
- [createThread](https://mastra.ai/reference/memory/createThread)
- [recall](https://mastra.ai/reference/memory/recall)
- [getThreadById](https://mastra.ai/reference/memory/getThreadById)
- [listThreads](https://mastra.ai/reference/memory/listThreads)
- [deleteMessages](https://mastra.ai/reference/memory/deleteMessages)
- [cloneThread](https://mastra.ai/reference/memory/cloneThread)
- [Clone Utility Methods](https://mastra.ai/reference/memory/clone-utilities)