> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.walletstech.com/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.walletstech.com/_mcp/server.

# Add missing chains

POST https://your-endpoint.example.com/extend
Content-Type: application/json

A user's wallet set is fixed at `/create` time, so a user created before a chain was configured has no address on it. `/extend` derives and inserts wallets for the **missing chains only**.

The server proves ownership before adding anything: the mnemonic must derive one of the user's stored addresses (otherwise `403`), and the password must decrypt an existing keystore entry (otherwise `401`).

Idempotent — when nothing is missing you get `added: []`. The mnemonic is never returned or stored.

Reference: https://docs.walletstech.com/api-reference/wallets/extend-user

## OpenAPI Specification

```yaml
openapi: 3.1.0
info:
  title: Blockchain Wallet Service
  version: 1.0.0
paths:
  /extend:
    post:
      operationId: extendUser
      summary: Add missing chains
      description: >-
        A user's wallet set is fixed at `/create` time, so a user created before
        a chain was configured has no address on it. `/extend` derives and
        inserts wallets for the **missing chains only**.


        The server proves ownership before adding anything: the mnemonic must
        derive one of the user's stored addresses (otherwise `403`), and the
        password must decrypt an existing keystore entry (otherwise `401`).


        Idempotent — when nothing is missing you get `added: []`. The mnemonic
        is never returned or stored.
      tags:
        - wallets
      parameters:
        - name: Authorization
          in: header
          description: >-
            A 15-minute token from `/auth`. Required on every endpoint except
            `/auth`.
          required: true
          schema:
            type: string
        - name: X-Request-Id
          in: header
          description: >-
            Correlation id. Generated if omitted, echoed on every response, and
            written to the audit log.
          required: false
          schema:
            type: string
        - name: X-USER-ID
          in: header
          description: >-
            Sent by the trusted gateway. When present it **overrides** any
            `userId` in the body.
          required: false
          schema:
            $ref: '#/components/schemas/UserId'
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Wallets_extendUser_Response_200'
        '400':
          description: Bad Request
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Unauthorized
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '403':
          description: Forbidden
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '409':
          description: Conflict
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      requestBody:
        content:
          application/json:
            schema:
              type: object
              properties:
                userId:
                  $ref: '#/components/schemas/UserId'
                existingSeed:
                  $ref: '#/components/schemas/Mnemonic'
                password:
                  $ref: '#/components/schemas/Password'
              required:
                - userId
                - existingSeed
                - password
servers:
  - url: https://your-endpoint.example.com
    description: >-
      Placeholder. Each client is issued its own base URL — there is no shared
      public host. Replace this with the endpoint you were given.
components:
  schemas:
    UserId:
      type: string
      description: 24-character hex id, returned by `/create`.
      title: UserId
    Mnemonic:
      type: string
      description: bip39 seed phrase, validated with `bip39.validateMnemonic`.
      title: Mnemonic
    Password:
      type: string
      description: >-
        Keystore password (AES-256-GCM, scrypt KDF). Unrecoverable — required by
        `/send` and `/extend`.
      title: Password
    Chain:
      type: string
      enum:
        - BITCOIN
        - ETHEREUM
        - BNB
        - TRON
        - POLYGON
        - SOLANA
      title: Chain
    AddressMap:
      type: object
      additionalProperties:
        type: string
      description: One address per chain the user holds a wallet on.
      title: AddressMap
    ExtendPostResponsesContentApplicationJsonSchemaResult:
      type: object
      properties:
        userId:
          $ref: '#/components/schemas/UserId'
        added:
          type: array
          items:
            $ref: '#/components/schemas/Chain'
          description: >-
            Chains added by this call. Empty when the user already had every
            configured chain.
        addresses:
          $ref: '#/components/schemas/AddressMap'
      required:
        - userId
        - added
        - addresses
      title: ExtendPostResponsesContentApplicationJsonSchemaResult
    RequestId:
      type: string
      description: Echo of the inbound `X-Request-Id`, or a generated one.
      title: RequestId
    Wallets_extendUser_Response_200:
      type: object
      properties:
        result:
          $ref: >-
            #/components/schemas/ExtendPostResponsesContentApplicationJsonSchemaResult
        requestId:
          $ref: '#/components/schemas/RequestId'
      required:
        - result
        - requestId
      title: Wallets_extendUser_Response_200
    ErrorResponse:
      type: object
      properties:
        message:
          type: string
          description: Safe, client-facing message. Internal detail never leaks here.
        error:
          type: string
          description: The HTTP status code, as a string.
        requestId:
          $ref: '#/components/schemas/RequestId'
      required:
        - message
        - error
        - requestId
      title: ErrorResponse
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: >-
        A 15-minute token from `/auth`. Required on every endpoint except
        `/auth`.

```

## Examples

### Chains added



**Request**

```json
{
  "userId": "66b1f0c23d4e4a5b9c6d7e8f",
  "existingSeed": "<your 12-word seed phrase — returned once, never again>",
  "password": "changeme123"
}
```

**Response**

```json
{
  "result": {
    "userId": "66b1f0c23d4e4a5b9c6d7e8f",
    "added": [
      "SOLANA"
    ],
    "addresses": {
      "BITCOIN": "bc1q5psk2q8t4x495ap75zghxmyvlmk59lr2u93r6j",
      "BNB": "0xc0c548339ee2af89c078200cabd1b7c7b47d911a",
      "ETHEREUM": "0xc0c548339ee2af89c078200cabd1b7c7b47d911a",
      "POLYGON": "0xc0c548339ee2af89c078200cabd1b7c7b47d911a",
      "SOLANA": "EB81pobCpSX16xKeuwYyNMDuZEcpWuHcmimQ9LbdT63d",
      "TRON": "THxvJmtZghePy5XqDE7HKawvFAsAgxcWZt"
    }
  },
  "requestId": "b7a1f0c2-3d4e-4a5b-9c6d-7e8f90a1b2c3"
}
```

**SDK Code**

```python Chains added
import requests

url = "https://your-endpoint.example.com/extend"

payload = {
    "userId": "66b1f0c23d4e4a5b9c6d7e8f",
    "existingSeed": "<your 12-word seed phrase — returned once, never again>",
    "password": "changeme123"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.json())
```

```javascript Chains added
const url = 'https://your-endpoint.example.com/extend';
const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: '{"userId":"66b1f0c23d4e4a5b9c6d7e8f","existingSeed":"<your 12-word seed phrase — returned once, never again>","password":"changeme123"}'
};

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

```go Chains added
package main

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

func main() {

	url := "https://your-endpoint.example.com/extend"

	payload := strings.NewReader("{\n  \"userId\": \"66b1f0c23d4e4a5b9c6d7e8f\",\n  \"existingSeed\": \"<your 12-word seed phrase — returned once, never again>\",\n  \"password\": \"changeme123\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

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

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

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

}
```

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

url = URI("https://your-endpoint.example.com/extend")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"userId\": \"66b1f0c23d4e4a5b9c6d7e8f\",\n  \"existingSeed\": \"<your 12-word seed phrase — returned once, never again>\",\n  \"password\": \"changeme123\"\n}"

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

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

HttpResponse<String> response = Unirest.post("https://your-endpoint.example.com/extend")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"userId\": \"66b1f0c23d4e4a5b9c6d7e8f\",\n  \"existingSeed\": \"<your 12-word seed phrase — returned once, never again>\",\n  \"password\": \"changeme123\"\n}")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://your-endpoint.example.com/extend', [
  'body' => '{
  "userId": "66b1f0c23d4e4a5b9c6d7e8f",
  "existingSeed": "<your 12-word seed phrase — returned once, never again>",
  "password": "changeme123"
}',
  'headers' => [
    'Authorization' => 'Bearer <token>',
    'Content-Type' => 'application/json',
  ],
]);

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

```csharp Chains added
using RestSharp;

var client = new RestClient("https://your-endpoint.example.com/extend");
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "Bearer <token>");
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"userId\": \"66b1f0c23d4e4a5b9c6d7e8f\",\n  \"existingSeed\": \"<your 12-word seed phrase — returned once, never again>\",\n  \"password\": \"changeme123\"\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift Chains added
import Foundation

let headers = [
  "Authorization": "Bearer <token>",
  "Content-Type": "application/json"
]
let parameters = [
  "userId": "66b1f0c23d4e4a5b9c6d7e8f",
  "existingSeed": "<your 12-word seed phrase — returned once, never again>",
  "password": "changeme123"
] as [String : Any]

let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

let request = NSMutableURLRequest(url: NSURL(string: "https://your-endpoint.example.com/extend")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers
request.httpBody = postData as Data

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()
```

### Nothing missing



**Request**

```json
{
  "userId": "66b1f0c23d4e4a5b9c6d7e8f",
  "existingSeed": "<your 12-word seed phrase — returned once, never again>",
  "password": "changeme123"
}
```

**Response**

```json
{
  "result": {
    "userId": "66b1f0c23d4e4a5b9c6d7e8f",
    "added": [],
    "addresses": {
      "BITCOIN": "bc1q5psk2q8t4x495ap75zghxmyvlmk59lr2u93r6j",
      "BNB": "0xc0c548339ee2af89c078200cabd1b7c7b47d911a",
      "ETHEREUM": "0xc0c548339ee2af89c078200cabd1b7c7b47d911a",
      "POLYGON": "0xc0c548339ee2af89c078200cabd1b7c7b47d911a",
      "SOLANA": "EB81pobCpSX16xKeuwYyNMDuZEcpWuHcmimQ9LbdT63d",
      "TRON": "THxvJmtZghePy5XqDE7HKawvFAsAgxcWZt"
    }
  },
  "requestId": "b7a1f0c2-3d4e-4a5b-9c6d-7e8f90a1b2c3"
}
```

**SDK Code**

```python Nothing missing
import requests

url = "https://your-endpoint.example.com/extend"

payload = {
    "userId": "66b1f0c23d4e4a5b9c6d7e8f",
    "existingSeed": "<your 12-word seed phrase — returned once, never again>",
    "password": "changeme123"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.json())
```

```javascript Nothing missing
const url = 'https://your-endpoint.example.com/extend';
const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: '{"userId":"66b1f0c23d4e4a5b9c6d7e8f","existingSeed":"<your 12-word seed phrase — returned once, never again>","password":"changeme123"}'
};

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

```go Nothing missing
package main

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

func main() {

	url := "https://your-endpoint.example.com/extend"

	payload := strings.NewReader("{\n  \"userId\": \"66b1f0c23d4e4a5b9c6d7e8f\",\n  \"existingSeed\": \"<your 12-word seed phrase — returned once, never again>\",\n  \"password\": \"changeme123\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

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

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

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

}
```

```ruby Nothing missing
require 'uri'
require 'net/http'

url = URI("https://your-endpoint.example.com/extend")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"userId\": \"66b1f0c23d4e4a5b9c6d7e8f\",\n  \"existingSeed\": \"<your 12-word seed phrase — returned once, never again>\",\n  \"password\": \"changeme123\"\n}"

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

```java Nothing missing
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.post("https://your-endpoint.example.com/extend")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"userId\": \"66b1f0c23d4e4a5b9c6d7e8f\",\n  \"existingSeed\": \"<your 12-word seed phrase — returned once, never again>\",\n  \"password\": \"changeme123\"\n}")
  .asString();
```

```php Nothing missing
<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://your-endpoint.example.com/extend', [
  'body' => '{
  "userId": "66b1f0c23d4e4a5b9c6d7e8f",
  "existingSeed": "<your 12-word seed phrase — returned once, never again>",
  "password": "changeme123"
}',
  'headers' => [
    'Authorization' => 'Bearer <token>',
    'Content-Type' => 'application/json',
  ],
]);

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

```csharp Nothing missing
using RestSharp;

var client = new RestClient("https://your-endpoint.example.com/extend");
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "Bearer <token>");
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"userId\": \"66b1f0c23d4e4a5b9c6d7e8f\",\n  \"existingSeed\": \"<your 12-word seed phrase — returned once, never again>\",\n  \"password\": \"changeme123\"\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift Nothing missing
import Foundation

let headers = [
  "Authorization": "Bearer <token>",
  "Content-Type": "application/json"
]
let parameters = [
  "userId": "66b1f0c23d4e4a5b9c6d7e8f",
  "existingSeed": "<your 12-word seed phrase — returned once, never again>",
  "password": "changeme123"
] as [String : Any]

let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

let request = NSMutableURLRequest(url: NSURL(string: "https://your-endpoint.example.com/extend")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers
request.httpBody = postData as Data

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()
```