---
title: "Continue an agent thread in a new one the caller owns"
method: POST
path: "/api/agent-threads/{threadId}/fork"
tags: ["Agent Threads"]
---

# Continue an agent thread in a new one the caller owns

`POST /api/agent-threads/{threadId}/fork`

## Request

- The document declares no server URL.
- Auth: one of:
  - API key in header `x-sixb-csrf`
  - HTTP bearer

## Path parameters

- `threadId` string, required

## Response `201`

Response for status 201

- object
  - `thread` object, required
    - `sandboxState` object
      - `name` string, required
      - `status` 'new' | 'busy' | 'ready' | 'blocked' | 'unavailable', required
      - `initialized` boolean, required
    - `id` string, required
    - `projectId` string, required
    - `ownerPrincipal` object, required
      - `type` 'user' | 'serviceAccount' | 'system', required
      - `id` string, required
    - `owner` object, required
      - `type` 'user' | 'serviceAccount' | 'system', required
      - `id` string, required
      - `displayName` string
    - `participants` object[], required
      - `principal` object, required
        - `type` 'user', required
        - `id` string, required
        - `displayName` string
      - `addedAt` string, required
      - `addedBy` object, required
        - `type` 'user' | 'serviceAccount' | 'system', required
        - `id` string, required
    - `title` string
    - `sandboxParams` object
    - `status` 'active' | 'archived', required
    - `activeRunId` string, nullable, required
    - `lastMessageAt` string
    - `messageCount` number, required
    - `createdAt` string, required
    - `updatedAt` string, required

## Other responses

- `400`: Response for status 400
- `404`: Response for status 404
- `501`: Response for status 501

## Changes

- **2026-10-20** `918d30b2ca67`: 1 info
  - endpoint added
- **2026-10-20** `cf4eafa4502e`: 1 breaking
  - api path removed without deprecation
- **2026-10-20** `e7589d61175d`: 1 info
  - endpoint added
- **2026-10-20** `1c47601b37c0`: 1 breaking
  - api path removed without deprecation
- **2026-10-20** `ebeab1520daa`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/sixb-ai/apis/sixb-api/changes/api/agent-threads/:threadId/fork/post.md)

---

[API](https://skmtc.dev/sixb-ai/apis/sixb-api.md) - [All operations](https://skmtc.dev/sixb-ai/apis/sixb-api/llms.txt) - [OpenAPI document](https://skmtc.dev/sixb-ai/apis/sixb-api/revisions/a227d682eaa2?raw)