# Memory.cloneThread()

The `.cloneThread()` method creates a copy of an existing conversation thread, including all its messages. This enables creating divergent conversation paths from a specific point in a conversation. When semantic recall is enabled, the method also creates vector embeddings for the cloned messages.

## Usage Example

```typescript
const { thread, clonedMessages } = await memory.cloneThread({
  sourceThreadId: "original-thread-123",
});
```

## Parameters

**sourceThreadId:** (`string`): The ID of the thread to clone

**newThreadId?:** (`string`): Optional custom ID for the cloned thread. If not provided, one will be generated.

**resourceId?:** (`string`): Optional resource ID for the cloned thread. Defaults to the source thread's resourceId.

**title?:** (`string`): Optional title for the cloned thread. Defaults to '\[source title] (Copy)'.

**metadata?:** (`Record<string, unknown>`): Optional metadata to merge with the source thread's metadata. Clone metadata is automatically added.

**options?:** (`CloneOptions`): Optional filtering options for the clone operation.

### Options Parameters

**messageLimit?:** (`number`): Maximum number of messages to clone. When set, clones the most recent N messages.

**messageFilter?:** (`MessageFilter`): Filter criteria for selecting which messages to clone.

### MessageFilter Parameters

**startDate?:** (`Date`): Only clone messages created on or after this date.

**endDate?:** (`Date`): Only clone messages created on or before this date.

**messageIds?:** (`string[]`): Only clone messages with these specific IDs.

## Returns

**thread:** (`StorageThreadType`): The newly created cloned thread with clone metadata.

**clonedMessages:** (`MastraDBMessage[]`): Array of the cloned messages with new IDs assigned to the new thread.

### Clone Metadata

The cloned thread's metadata includes a `clone` property with:

**sourceThreadId:** (`string`): The ID of the original thread that was cloned.

**clonedAt:** (`Date`): Timestamp when the clone was created.

**lastMessageId?:** (`string`): The ID of the last message in the source thread at the time of cloning.

## Extended Usage Example

```typescript
import { mastra } from "./mastra";

const agent = mastra.getAgent("agent");
const memory = await agent.getMemory();

// Clone a thread with all messages
const { thread: fullClone } = await memory.cloneThread({
  sourceThreadId: "original-thread-123",
  title: "Alternative Conversation Path",
});

// Clone with a custom ID
const { thread: customIdClone } = await memory.cloneThread({
  sourceThreadId: "original-thread-123",
  newThreadId: "my-custom-clone-id",
});

// Clone only the last 5 messages
const { thread: partialClone, clonedMessages } = await memory.cloneThread({
  sourceThreadId: "original-thread-123",
  options: {
    messageLimit: 5,
  },
});

// Clone messages from a specific date range
const { thread: dateFilteredClone } = await memory.cloneThread({
  sourceThreadId: "original-thread-123",
  options: {
    messageFilter: {
      startDate: new Date("2024-01-01"),
      endDate: new Date("2024-01-31"),
    },
  },
});

// Continue conversation on the cloned thread
const response = await agent.generate("Let's try a different approach", {
  threadId: fullClone.id,
  resourceId: fullClone.resourceId,
});
```

## Vector Embeddings

When the Memory instance has semantic recall enabled (with a vector store and embedder configured), `cloneThread()` automatically creates vector embeddings for all cloned messages. This ensures that semantic search works correctly on the cloned thread.

```typescript
import { Memory } from "@mastra/memory";
import { LibSQLStore, LibSQLVector } from "@mastra/libsql";

const memory = new Memory({
  storage: new LibSQLStore({ id: 'memory-store', url: "file:./memory.db" }),
  vector: new LibSQLVector({ id: 'vector-store', url: "file:./vector.db" }),
  embedder: embeddingModel,
  options: {
    semanticRecall: true,
  },
});

// Clone will also create embeddings for cloned messages
const { thread } = await memory.cloneThread({
  sourceThreadId: "original-thread",
});

// Semantic search works on the cloned thread
const results = await memory.recall({
  threadId: thread.id,
  vectorSearchString: "search query",
});
```

### Related

- [Memory Class Reference](https://mastra.ai/reference/memory/memory-class)
- [createThread](https://mastra.ai/reference/memory/createThread)
- [Clone Utility Methods](https://mastra.ai/reference/memory/clone-utilities)
- [recall](https://mastra.ai/reference/memory/recall)
- [Semantic Recall](https://mastra.ai/docs/memory/semantic-recall)