> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# Diff two versions

GET https://api.smallest.ai/atoms/v1/agent/{id}/versions/diff

**Deprecated.** Kept working during the v1 coexistence window (\~1 month). Migrate to `GET /agent/{id}/diff?a=<revisionId>&b=<revisionId>`. Will be removed at the sunset date.

Compare two version or draft revision records side-by-side by their IDs. The implementation tries published versions first and can fall back to the latest draft revision.

Reference: https://docs.smallest.ai/api-reference/voice-agents/agent-versioning-versions/diff-two-versions

## Authentication

- `Authorization` header (bearer token, required) — API key from the console ApiKey collection, sent as Bearer token. Also accepts session cookies for browser-based auth.

## Request

### Path parameters

- `id` (string, required) — The agent ID.

### Query parameters

- `versionA` (string, required) — ID of the first version
- `versionB` (string, required) — ID of the second version

## Response

### 200

Diff returned successfully

- `status` (boolean, optional)
- `data` (AgentVersionDiff, optional) — Section-by-section diff between two version or draft revision records.

## Errors

### 400 Bad Request Error

Invalid input

- `status` (boolean, optional)
- `errors` (list of string, optional)

### 401 Unauthorized Error

Unauthorized access

- `status` (boolean, optional)
- `errors` (list of string, optional)

### 403 Forbidden Error

Forbidden. Returned for workflow_graph agents when the organization lacks conversational agents access.

- `status` (boolean, optional)
- `data` (ApiResponseData, optional)

### 404 Not Found Error

Agent or version not found

- `status` (boolean, optional)
- `errors` (list of string, optional)

### 500 Internal Server Error

Internal server error

- `status` (boolean, optional)
- `errors` (list of string, optional)

## Types

### AgentVersionDiff

Section-by-section diff between two version or draft revision records.

- `unchangedSections` (list of string, optional) — Config sections that did not change.
- `diffs` (list of AgentVersionDiffDiffsItems, optional) — Config sections with one or more changes.

### ApiResponseData

### AgentVersionDiffDiffsItems

- `section` (string, optional) — Config section name.
- `changes` (list of AgentVersionDiffDiffsItemsChangesItems, optional)

### AgentVersionDiffDiffsItemsChangesItems

- `path` (string, optional) — Path to the changed value within the section.
- `oldValue` (AgentVersionDiffDiffsItemsChangesItemsOldValue, optional, nullable) — Previous value. Can be any JSON value or null.
- `newValue` (AgentVersionDiffDiffsItemsChangesItemsNewValue, optional, nullable) — New value. Can be any JSON value or null.

### AgentVersionDiffDiffsItemsChangesItemsOldValue

Previous value. Can be any JSON value or null.

### AgentVersionDiffDiffsItemsChangesItemsNewValue

New value. Can be any JSON value or null.

## Examples

**Response**

```json
{
  "status": true,
  "data": {
    "unchangedSections": [
      "string"
    ],
    "diffs": [
      {
        "section": "string",
        "changes": [
          {
            "path": "string",
            "oldValue": {},
            "newValue": {}
          }
        ]
      }
    ]
  }
}
```

**SDK Code**

```python
import requests

url = "https://api.smallest.ai/atoms/v1/agent/id/versions/diff"

querystring = {"versionA":"versionA","versionB":"versionB"}

headers = {"Authorization": "Bearer <token>"}

response = requests.get(url, headers=headers, params=querystring)

print(response.json())
```

```javascript
const url = 'https://api.smallest.ai/atoms/v1/agent/id/versions/diff?versionA=versionA&versionB=versionB';
const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

try {
  const response = await fetch(url, options);
  const data = await response.json();
  console.log(data);
} catch (error) {
  console.error(error);
}
```

```go
package main

import (
	"fmt"
	"net/http"
	"io"
)

func main() {

	url := "https://api.smallest.ai/atoms/v1/agent/id/versions/diff?versionA=versionA&versionB=versionB"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("Authorization", "Bearer <token>")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}
```

```ruby
require 'uri'
require 'net/http'

url = URI("https://api.smallest.ai/atoms/v1/agent/id/versions/diff?versionA=versionA&versionB=versionB")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Get.new(url)
request["Authorization"] = 'Bearer <token>'

response = http.request(request)
puts response.read_body
```

```java
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.get("https://api.smallest.ai/atoms/v1/agent/id/versions/diff?versionA=versionA&versionB=versionB")
  .header("Authorization", "Bearer <token>")
  .asString();
```

```php
<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('GET', 'https://api.smallest.ai/atoms/v1/agent/id/versions/diff?versionA=versionA&versionB=versionB', [
  'headers' => [
    'Authorization' => 'Bearer <token>',
  ],
]);

echo $response->getBody();
```

```csharp
using RestSharp;

var client = new RestClient("https://api.smallest.ai/atoms/v1/agent/id/versions/diff?versionA=versionA&versionB=versionB");
var request = new RestRequest(Method.GET);
request.AddHeader("Authorization", "Bearer <token>");
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = ["Authorization": "Bearer <token>"]

let request = NSMutableURLRequest(url: NSURL(string: "https://api.smallest.ai/atoms/v1/agent/id/versions/diff?versionA=versionA&versionB=versionB")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "GET"
request.allHTTPHeaderFields = headers

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error as Any)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()
```