---
title: "Open a changeset"
description: "Start a change spread over several calls that becomes one history entry."
canonical: "https://atelier201.com/docs/api/changesets/open"
updated: "2026-11-06"
---

# Open a changeset

Requires `sites:write`. Costs no credits.

A changeset has four steps: open it, [stage files](/docs/api/changesets/patch), then [commit](/docs/api/changesets/commit) or [abandon](/docs/api/changesets/abandon) it. It stays open for 10 minutes, then it is committed if valid or abandoned.

Use a changeset when a change needs several calls, for example a new page, its content and its image. A single call that changes several files does not need one: [Change files](/docs/api/files/commit) is already one entry.

```http
POST https://api.atelier201.com/v1/sites/{site_id}/changesets
```

## Authorizations

- `Authorization` (bearer, in header, required)

## Path parameters

- `site_id` (`string`, required): The site's id, or its slug (the address before .atelier201.page).

## Body

`application/json`, required

- `summary` (`string`, required, length: `1–500 chars`)
- `base_revision` (`string`, length: `40–40 chars`): A Git commit id (40 hex characters) of the site's repository.

## Response

**201**: Open a changeset

- `data` (`object`, required)
- `data.id` (`string`, required)
- `data.changeset_id` (`string`, required): The id stage_changes, commit_changeset and abandon_changeset take (the same as id).
- `data.base_revision` (`string`, required, length: `40–40 chars`): A Git commit id (40 hex characters) of the site's repository.
- `data.expires_at` (`string`, required): ISO 8601, UTC.
- `request_id` (`string`, required)

```json
{
  "data": {
    "id": "<string>",
    "changeset_id": "<string>",
    "base_revision": "<string>",
    "expires_at": "<string>"
  },
  "request_id": "<string>"
}
```

**400**: Possible codes: invalid_request, unknown_field, invalid_parameter, invalid_cursor

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**401**: Possible codes: authentication_required, invalid_api_key, api_key_expired, api_key_revoked

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**402**: Possible codes: insufficient_credits

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**403**: Possible codes: insufficient_scope, feature_not_available, admin_required

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**404**: Possible codes: resource_not_found

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**409**: Possible codes: conflict, result_not_ready, idempotency_key_reused

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**410**: Possible codes: result_expired

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**413**: Possible codes: request_too_large

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**422**: Possible codes: request_too_large_for_plan

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**429**: Possible codes: rate_limited

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**500**: Possible codes: internal_error

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**503**: Possible codes: service_unavailable

- `error` (`object`, required)
- `error.type` (`string`, required)
- `error.code` (`string`, required)
- `error.message` (`string`, required)
- `error.param` (`string`)
- `error.docs_url` (`string`, required)
- `error.action_url` (`string<uri>`)
- `error.details` (`Record<string, object>`)
- `request_id` (`string`, required)

```json
{
  "error": {
    "type": "<string>",
    "code": "<string>",
    "message": "<string>",
    "param": "<string>",
    "docs_url": "<string>",
    "action_url": "<string>",
    "details": {}
  },
  "request_id": "<string>"
}
```

**Example request**

```bash
curl --request POST \
  --url 'https://api.atelier201.com/v1/sites/<site_id>/changesets' \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '{
  "summary": "<string>"
}'
```