# claim

URL: /business/nouns/domain/claim · Id: `verb:Domain.claim` · Call: `await $.Domain.claim({ … })` (SDK) or the `do` tool at `https://api.sb/mcp`. Inputs says what to pass, Outputs what returns, When it waits who approves.

> Claim gives a Startup a one-label name under an issuing Domain, or assigns it a held Domain through an approved Change.

Claim gives a [Startup](/business/nouns/startup) a one-label name under an issuing [Domain](/business/nouns/domain), or assigns it a held Domain through an approved [Change](/business/nouns/change).

## Inputs
| Input | Type | Required | Description |
| --- | --- | --- | --- |
| `hostname` | `string` | Yes | The name to claim. |
| `startup` | [Startup](/business/nouns/startup) | Yes | The Startup it serves. |

## Outputs
| Output | Type | Required | Description |
| --- | --- | --- | --- |
| `domain` | [Domain](/business/nouns/domain) | Yes | The claimed Domain. |

## Effects
- Emits [`Domain.claimed`](/business/events/Domain.claimed).
- Performed by the [Engineering Lead](/agents/engineering/engineering-lead).
- Two-way: it runs at once, in the `try`, `send` and `do` modes.
- Refuses a label under an issuing Domain whose `publicSuffix` is false.
- Refuses reserved labels such as `www`, `api`, `admin`, `mail`, `mcp`, `docs` and sibling Brands.
- Never reissues a label released or renamed before.

## Refuses when
| Check | Error | Fix | Then call |
| --- | --- | --- | --- |
| The key is valid, but its scopes do not allow this operation. | [`forbidden`](/code/api/errors/forbidden) | Use a key whose scopes cover the operation, or ask an owner of the namespace to grant them. | [Domain.claim](/business/nouns/domain/claim) |
| A label under an issuing Domain whose `publicSuffix` is false | [`refused`](/code/api/errors/refused) | Clear what the check names, then call it again. | [Domain.claim](/business/nouns/domain/claim) |
| Reserved labels such as `www`, `api`, `admin`, `mail`, `mcp`, `docs` and sibling Brands | [`refused`](/code/api/errors/refused) | Clear what the check names, then call it again. | [Domain.claim](/business/nouns/domain/claim) |

## When it waits
| Gate | Default |
| --- | --- |
| Decision class | Low: two-way, nothing at stake |
| [Delay window](/systems/trust-and-governance/controls/one-way-windows) | None: it runs once review passes. |
| Limit | The call [Limit](/business/nouns/limit) of the [Permission](/business/nouns/permission) it runs under. |
| Over the Limit | It waits `pending` for an [Approval](/business/nouns/approval) from the [Founder](/agents/founding/founder). Approved, it runs; refused, it ends `refused` with [`limit-exceeded`](/code/api/errors/limit-exceeded); unanswered by its deadline, it ends `canceled`. |

## Example

**Ask**

```text
Claim the domain “acme.headless.ly” with a startup.
```

**API**

```bash
curl -X POST https://api.sb/quietcopy.com/domains/claim \
  -H "Authorization: Bearer $STARTUP_BUILDER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"hostname":"acme.headless.ly","startup":"startup_1"}'
```

```json
{
  "api": "https://api.sb/quietcopy.com",
  "domain": {
    "$id": "https://api.sb/quietcopy.com/domains/domain_1",
    "$type": "Domain",
    "hostname": "quietcopy.com",
    "role": "canonical",
    "state": "verifying"
  },
  "action": {
    "$id": "https://api.sb/quietcopy.com/actions/action_1",
    "operation": "Domain.claim",
    "status": "done"
  },
  "links": {
    "self": "https://api.sb/quietcopy.com/actions/action_1"
  }
}
```

**SDK**

```ts
import { $ } from 'startup-builder'

const domain = await $.Domain.claim({ hostname: 'acme.headless.ly', startup: 'startup_1' })
```

**CLI**

```bash
npx startup-builder do Domain.claim --json '{"hostname":"acme.headless.ly","startup":"startup_1"}'
```

**MCP**

```json
{
  "name": "do",
  "arguments": {
    "code": "return await $.Domain.claim({ hostname: 'acme.headless.ly', startup: 'startup_1' })"
  }
}
```

Next: [`Site.publish`](/business/nouns/site/publish) (in `guide:put-up-a-page`).

Guides that call it: [Put up a page](/start/guides/put-up-a-page).