curl --request POST \
  --url https://api.checkfu.com/v1/sessions/{id}/fork \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'checkfu-version: <checkfu-version>' \
  --header 'idempotency-key: <idempotency-key>' \
  --data '
{
  "at_event": "<unknown>",
  "checkpoint": "<unknown>"
}
'

import requests

url = "https://api.checkfu.com/v1/sessions/{id}/fork"

payload = {
    "at_event": "<unknown>",
    "checkpoint": "<unknown>"
}
headers = {
    "checkfu-version": "<checkfu-version>",
    "idempotency-key": "<idempotency-key>",
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {
    'checkfu-version': '<checkfu-version>',
    'idempotency-key': '<idempotency-key>',
    Authorization: 'Bearer <token>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({at_event: '<unknown>', checkpoint: '<unknown>'})
};

fetch('https://api.checkfu.com/v1/sessions/{id}/fork', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.checkfu.com/v1/sessions/{id}/fork",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'at_event' => '<unknown>',
    'checkpoint' => '<unknown>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json",
    "checkfu-version: <checkfu-version>",
    "idempotency-key: <idempotency-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

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

func main() {

	url := "https://api.checkfu.com/v1/sessions/{id}/fork"

	payload := strings.NewReader("{\n  \"at_event\": \"<unknown>\",\n  \"checkpoint\": \"<unknown>\"\n}")

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

	req.Header.Add("checkfu-version", "<checkfu-version>")
	req.Header.Add("idempotency-key", "<idempotency-key>")
	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(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.checkfu.com/v1/sessions/{id}/fork")
  .header("checkfu-version", "<checkfu-version>")
  .header("idempotency-key", "<idempotency-key>")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"at_event\": \"<unknown>\",\n  \"checkpoint\": \"<unknown>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.checkfu.com/v1/sessions/{id}/fork")

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

request = Net::HTTP::Post.new(url)
request["checkfu-version"] = '<checkfu-version>'
request["idempotency-key"] = '<idempotency-key>'
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"at_event\": \"<unknown>\",\n  \"checkpoint\": \"<unknown>\"\n}"

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

{
  "id": "<string>",
  "agent": {
    "id": "<string>",
    "description": "<string>",
    "harness": "<string>",
    "mcp_servers": [
      {
        "type": "url",
        "name": "<string>",
        "url": "<string>"
      }
    ],
    "model": {
      "id": "<string>",
      "effort": {
        "type": "low"
      },
      "inference_geo": "global",
      "speed": "standard"
    },
    "name": "<string>",
    "skills": [
      {
        "type": "anthropic",
        "skill_id": "<string>",
        "version": "<string>"
      }
    ],
    "system": "<string>",
    "tools": [
      {
        "type": "agent_toolset_20260401",
        "configs": [
          {
            "name": "bash",
            "type": "bash",
            "enabled": true,
            "permission_policy": {
              "type": "always_allow"
            }
          }
        ],
        "default_config": {
          "enabled": true,
          "permission_policy": {
            "type": "always_allow"
          }
        }
      }
    ],
    "multiagent": {
      "agents": [
        {
          "id": "<string>",
          "description": "<string>",
          "harness": "<string>",
          "mcp_servers": [
            {
              "type": "url",
              "name": "<string>",
              "url": "<string>"
            }
          ],
          "model": {
            "id": "<string>",
            "effort": {
              "type": "low"
            },
            "inference_geo": "global",
            "speed": "standard"
          },
          "name": "<string>",
          "skills": [
            {
              "type": "anthropic",
              "skill_id": "<string>",
              "version": "<string>"
            }
          ],
          "system": "<string>",
          "tools": [
            {
              "type": "agent_toolset_20260401",
              "configs": [
                {
                  "name": "bash",
                  "type": "bash",
                  "enabled": true,
                  "permission_policy": {
                    "type": "always_allow"
                  }
                }
              ],
              "default_config": {
                "enabled": true,
                "permission_policy": {
                  "type": "always_allow"
                }
              }
            }
          ],
          "type": "agent",
          "version": 1
        }
      ],
      "type": "coordinator"
    },
    "type": "agent",
    "version": 1
  },
  "archived_at": "<string>",
  "budget": {
    "type": "limit",
    "max_list_cost": {
      "amount": "<string>",
      "currency": "USD"
    }
  },
  "created_at": "<string>",
  "environment_id": "<string>",
  "metadata": {},
  "outcome_evaluations": [
    {
      "completed_at": "<string>",
      "description": "<string>",
      "explanation": "<string>",
      "iteration": 1,
      "outcome_id": "<string>",
      "result": "<string>",
      "type": "outcome_evaluation"
    }
  ],
  "resources": [
    {
      "id": "<string>",
      "created_at": "<string>",
      "updated_at": "<string>",
      "mount_path": "<string>",
      "type": "github_repository",
      "url": "<string>",
      "checkout": {
        "type": "branch",
        "name": "<string>"
      }
    }
  ],
  "stats": {
    "active_seconds": 1,
    "duration_seconds": 1
  },
  "status": "rescheduling",
  "title": "<string>",
  "type": "session",
  "updated_at": "<string>",
  "usage": {
    "active_seconds": 1,
    "cache_creation": {
      "ephemeral_1h_input_tokens": 1,
      "ephemeral_5m_input_tokens": 1
    },
    "cache_read_input_tokens": 1,
    "input_tokens": 1,
    "list_cost": {
      "amount": "<string>",
      "currency": "USD"
    },
    "output_tokens": 1,
    "server_tool_use": {
      "web_fetch_requests": 1,
      "web_search_requests": 1
    }
  },
  "vault_ids": [
    "<string>"
  ],
  "automation_id": "<string>"
}

{
  "target_session_id": "<string>",
  "status": "pending",
  "phase": "selecting_prefix",
  "cursor": 1,
  "retry_after_ms": 1
}

{
  "error": {
    "type": "validation.malformed",
    "message": "<string>",
    "more": "https://docs.checkfu.com/reference/errors#validation-malformed"
  }
}

{
  "error": {
    "type": "auth.invalid_key",
    "message": "<string>",
    "more": "https://docs.checkfu.com/reference/errors#auth-invalid-key"
  }
}

{
  "error": {
    "type": "auth.disabled_tenancy",
    "message": "<string>",
    "more": "https://docs.checkfu.com/reference/errors#auth-disabled-tenancy"
  }
}

{
  "error": {
    "type": "validation.not_found",
    "message": "<string>",
    "more": "https://docs.checkfu.com/reference/errors#validation-not-found"
  }
}

{
  "error": {
    "type": "validation.conflict",
    "message": "<string>",
    "more": "https://docs.checkfu.com/reference/errors#validation-conflict"
  }
}

{
  "error": {
    "type": "budget.exceeded",
    "message": "<string>",
    "more": "https://docs.checkfu.com/reference/errors#budget-exceeded"
  }
}

{
  "error": {
    "type": "runtime.internal",
    "message": "<string>",
    "more": "https://docs.checkfu.com/reference/errors#runtime-internal"
  }
}

{
  "error": {
    "type": "runtime.runner_unavailable",
    "message": "<string>",
    "more": "https://docs.checkfu.com/reference/errors#runtime-runner-unavailable"
  }
}