> ## Documentation Index > Fetch the complete documentation index at: https://docs.boat.dev/llms.txt > Use this file to discover all available pages before exploring further. # Fork box > Provision a new box from an existing one. Send an `Idempotency-Key` header to make this call safe to retry after a lost response without creating a second billable fork. ## OpenAPI ````yaml openapi/box-v1.yaml POST /boxes/{boxId}/fork openapi: 3.1.0 info: title: Boat Public API v1 version: 1.0.0 description: > Public JSON API for creating, operating, prompting, observing, and exposing Boat sandboxes from backend services, CI jobs, hosted workers, and Boat automation products. The v1 reference intentionally documents the developer integration surface only. Dashboard billing actions are not part of v1. servers: - url: https://ascii.dev/api/box/v1 security: - BoxBearerAuth: [] tags: - name: Box description: >- Unified Boat account, setup, lifecycle, prompting, event history, desktop access, and SSH operations. paths: /boxes/{boxId}/fork: post: tags: - Box summary: Fork box description: >- Provision a new box from an existing one. Send an `Idempotency-Key` header to make this call safe to retry after a lost response without creating a second billable fork. operationId: fork parameters: - $ref: '#/components/parameters/BoxId' - $ref: '#/components/parameters/IdempotencyKey' requestBody: required: false content: application/json: schema: type: object properties: env: type: object additionalProperties: type: string description: >- Replaces the env the fork would otherwise inherit from the source box. Same validation rules as `CreateBoxRequest.env`. environment: type: string description: >- Optionally pin the fork to a different named Boat environment. Omit to inherit the source box's environment. Unknown names are rejected with `unknown_environment`. examples: - base - customer-demos noEnv: type: boolean description: >- Make the fork no-env (see `CreateBoxRequest.noEnv`). A fork of a no-env box is always no-env regardless of this field. type: type: string enum: - small - default - large - xlarge description: >- Machine size for the fork. Omit to inherit the source box's type. The source box is never modified. Shrinking is rejected with `type_too_small` when the source's data would not fit the smaller disk. `xlarge` requires the effective $100 plan or higher and an explicit bare-metal operator allocation. ttlSeconds: oneOf: - type: integer minimum: 1 maximum: 2592000 - type: 'null' default: 3600 description: >- Auto-stop for the fork, in seconds. Omit for the 1 hour default; the fork does NOT inherit the source box's TTL, so forking a Boat that has auto-stop disabled still gives you a fork that stops itself. `null` disables auto-stop, which means nothing will ever stop this Boat for you. responses: '202': description: Fork started. The response `id` is the new forked box id. content: application/json: schema: $ref: '#/components/schemas/BoxActionResponse' examples: forking: value: ok: true type: box.forking id: bx_abcdef23 status: forking box: id: bx_abcdef23 name: Box fork state: provisioning desktopAvailable: false snapshotAvailable: false '401': $ref: '#/components/responses/Unauthorized' '402': $ref: '#/components/responses/PaymentRequired' '404': $ref: '#/components/responses/NotFound' '409': $ref: '#/components/responses/Conflict' '429': $ref: '#/components/responses/RateLimited' components: parameters: BoxId: name: boxId in: path required: true schema: type: string pattern: ^bx_[23456789abcdefghjkmnpqrstuvwxyz]{8}$ description: Public Box id returned by create/list/get box calls. IdempotencyKey: name: Idempotency-Key in: header required: false schema: type: string maxLength: 255 description: >- Optional exactly-once key for creating a box. Send your own opaque, account-unique value (a UUID) to make `POST /boxes` safe to retry when the response is lost (network timeout, 5xx): the first request creates the box and binds it to the key; every later request with the **same account, key, and request body** returns that same box instead of creating a second, billable one. Behavior: keys are retained for **24 hours**; a concurrent or early retry while the first box is still being minted returns `409` `idempotency_in_progress` (retry shortly, same key); reusing a key with a **different body** returns `409` `idempotency_key_reused`; timeouts and 5xx are safe to retry with the same key; a create that fails before the box exists releases the key within ~2 minutes so a retry can create the box. Omit the header to keep the default (non-idempotent) behavior. schemas: BoxActionResponse: allOf: - $ref: '#/components/schemas/SuccessBase' - type: object required: - id - status properties: type: type: string examples: - box.stopping id: type: string status: type: string examples: - archiving box: oneOf: - $ref: '#/components/schemas/Box' - type: 'null' SuccessBase: type: object required: - ok - type properties: ok: type: boolean examples: - true type: type: string description: Stable success envelope discriminator added by v1. Box: type: object required: - id - name - state - desktopAvailable - snapshotAvailable properties: id: type: string pattern: ^bx_[23456789abcdefghjkmnpqrstuvwxyz]{8}$ examples: - bx_23456789 name: type: string examples: - Box 2026-05-31 12:00 state: type: string enum: - init - provisioning - provisioned - cloning - ready - idle - running - archiving - archived - error type: type: string enum: - small - default - large - xlarge description: >- Current machine size: what the box was created with, or the size it was last resumed or forked onto. Legacy bare-metal boxes read as `default`. vcpu: type: integer description: vCPUs guaranteed by this box's type. examples: - 4 memoryGB: type: integer description: RAM in GB guaranteed by this box's type. examples: - 8 billingMultiplier: type: number description: >- Rate at which this box consumes machine time. 0.5 for `small`, 1 for `default`, 2 for `large`, and 50/9 for `xlarge`. examples: - 1 url: type: - string - 'null' format: uri description: Machine URL when assigned. ip: type: - string - 'null' description: Machine IPv6 or IPv4 address when assigned. createdAt: type: - string - 'null' format: date-time updatedAt: type: - string - 'null' format: date-time archiveAfter: type: - string - 'null' format: date-time description: Automatic archival time, or null when auto-stop is disabled. desktopAvailable: type: boolean desktopUrl: type: - string - 'null' format: uri description: Secret-bearing desktop stream URL when available. Redact from logs. snapshotAvailable: type: boolean snapshotCompletedAt: type: - string - 'null' format: date-time description: >- Timestamp of the most recent successfully completed snapshot, or null. subdomain: type: - string - 'null' description: >- The box's stable three-word subdomain slug (e.g. "frazil-pneuma-rallye"), or null before one is assigned. lastSnapshotAttemptAt: type: - string - 'null' format: date-time description: >- Timestamp of the most recent snapshot attempt of any status (queued, in_progress, completed, failed, cancelled), or null. Use with snapshotCompletedAt to detect snapshots that keep failing. lastSnapshotStatus: type: - string - 'null' enum: - queued - in_progress - completed - failed - cancelled - null description: >- Status of the most recent snapshot attempt, or null if none. A value other than completed while snapshotCompletedAt stays stale indicates failing snapshots. setupStatus: type: - string - 'null' enum: - pending - running - done - failed - null description: >- Outcome of the create-time `setupScript`: `pending` (stored, not yet started), `running` (executing on the box in the background), `done` (exit code 0) or `failed` (non-zero exit, or the box lost track of the process). Null when the box was created without a setup script. setupError: type: - string - 'null' description: >- Short failure detail (exit code plus a stderr tail) when `setupStatus` is `failed`; while `pending`, may carry the last start/upload error from a retry in progress. Otherwise null. environment: type: - string - 'null' description: >- Name of the Boat environment this box is running, or null if it is attached to none (a `noEnv` box, or one whose environment was deleted). A box freezes onto one environment version when it starts and keeps it for life, so this is what the box actually holds, not what the environment says today. examples: - base environmentVersion: type: - integer - 'null' description: >- Version number of `environment` that this box is pinned to. Compare it against the environment's latest version to see whether an upgrade is pending: a box below the latest is still running the older configuration until someone calls `POST /environments/{environmentId}/upgrade`. examples: - 3 ErrorEnvelope: type: object required: - ok - type - status - code - message - error - requestId properties: ok: type: boolean examples: - false type: type: string examples: - box.error status: type: integer examples: - 409 code: type: string examples: - provider_not_configured message: type: string examples: - Prompting is locked until Codex is configured on the Agents page. requestId: type: string examples: - req_01HX... error: type: object required: - code - message - status properties: code: type: string message: type: string status: type: integer details: type: object additionalProperties: true responses: Unauthorized: description: Missing or invalid bearer token. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' examples: unauthorized: value: ok: false type: box.error status: 401 code: unauthorized message: Unauthorized error: code: unauthorized message: Unauthorized status: 401 requestId: req_01HX... PaymentRequired: description: >- Account cannot currently create or operate Boxes. The error body may include a dashboard billing URL, but billing actions are not part of the v1 API. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' NotFound: description: Resource not found. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' Conflict: description: Request conflicts with current account or box state. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' RateLimited: description: >- Machine start or concurrent-box limit reached. Create, fork and resume each count as one machine start against your plan's start limits (see the Billing guide; `rate_limited`, naming the window you hit). A box that would exceed your plan's concurrent-box cap is refused with `limit_reached`, or `member_limit_reached` when an organization owner has capped you below the plan. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' securitySchemes: BoxBearerAuth: type: http scheme: bearer bearerFormat: box_api_key description: >- Boat bearer token in the form `box_...`. Service API keys authenticate Boat operations. ````