langgraph/docs/docs/cloud/how-tos/copy_threads.md

Copying Threads

You may wish to copy (i.e. "fork") an existing thread in order to keep the existing thread's history and create independent runs that do not affect the original thread. This guide shows how you can do that.

Setup

This code assumes you already have a thread to copy. You can read about what a thread is here and learn how to stream a run on a thread in these how-to guides.

SDK initialization

First, we need to setup our client so that we can communicate with our hosted graph:

=== "Python"

```python
from langgraph_sdk import get_client
client = get_client(url="<DEPLOYMENT_URL>")
assistant_id = "agent"
thread = await client.threads.create()
```

=== "Javascript"

```js
import { Client } from "@langchain/langgraph-sdk";

const client = new Client({ apiUrl: "<DEPLOYMENT_URL>" });
const assistantId = "agent";
const thread = await client.threads.create();
```

=== "CURL"

```bash
curl --request POST \
  --url <DEPLOYMENT_URL>/threads \
  --header 'Content-Type: application/json' \
  --data '{
    "metadata": {}
  }'
```

Copying a thread

The code below assumes that a thread you'd like to copy already exists.

Copying a thread will create a new thread with the same history as the existing thread, and then allow you to continue executing runs.

Create copy

=== "Python"

```python
copied_thread = await client.threads.copy(<THREAD_ID>)
```

=== "Javascript"

```js
let copiedThread = await client.threads.copy(<THREAD_ID>);
```

=== "CURL"

```bash
curl --request POST --url <DEPLOYMENT_URL>/threads/<THREAD_ID>/copy \
--header 'Content-Type: application/json'
```

Verify copy

We can verify that the history from the prior thread did indeed copy over correctly:

=== "Python"

```python
def remove_thread_id(d):
  if 'metadata' in d and 'thread_id' in d['metadata']:
      del d['metadata']['thread_id']
  return d

original_thread_history = list(map(remove_thread_id,await client.threads.get_history(<THREAD_ID>)))
copied_thread_history = list(map(remove_thread_id,await client.threads.get_history(copied_thread['thread_id'])))

# Compare the two histories
assert original_thread_history == copied_thread_history
# if we made it here the assertion passed!
print("The histories are the same.")
```

=== "Javascript"

```js
function removeThreadId(d) {
  if (d.metadata && d.metadata.thread_id) {
    delete d.metadata.thread_id;
  }
  return d;
}

// Assuming `client.threads.getHistory(threadId)` is an async function that returns a list of dicts
async function compareThreadHistories(threadId, copiedThreadId) {
  const originalThreadHistory = (await client.threads.getHistory(threadId)).map(removeThreadId);
  const copiedThreadHistory = (await client.threads.getHistory(copiedThreadId)).map(removeThreadId);

  // Compare the two histories
  console.assert(JSON.stringify(originalThreadHistory) === JSON.stringify(copiedThreadHistory));
  // if we made it here the assertion passed!
  console.log("The histories are the same.");
}

// Example usage
compareThreadHistories(<THREAD_ID>, copiedThread.thread_id);
```

=== "CURL"

```bash
if diff <(
    curl --request GET --url <DEPLOYMENT_URL>/threads/<THREAD_ID>/history | jq -S 'map(del(.metadata.thread_id))'
) <(
    curl --request GET --url <DEPLOYMENT_URL>/threads/<COPIED_THREAD_ID>/history | jq -S 'map(del(.metadata.thread_id))'
) >/dev/null; then
    echo "The histories are the same."
else
    echo "The histories are different."
fi
```

Output:

The histories are the same.