# extend

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

> Extend adds a Template to a Startup’s bases, pinned to a Version, so the Startup inherits its definition.

Extend adds a [Template](/business/nouns/template) to a [Startup](/business/nouns/startup)’s bases, pinned to a [Version](/business/nouns/version), so the Startup inherits its definition.

## Inputs
| Input | Type | Required | Description |
| --- | --- | --- | --- |
| `template` | [Template](/business/nouns/template) | Yes | The Template to inherit. |
| `startup` | [Startup](/business/nouns/startup) | Yes | The Startup that extends it. |

## Outputs
| Output | Type | Required | Description |
| --- | --- | --- | --- |
| `startup` | [Startup](/business/nouns/startup) | Yes | The Startup with the Template among its bases. |
| `template` | [Template](/business/nouns/template) | Yes | The Template extended. |

## Effects
- Emits [`Template.extended`](/business/events/Template.extended).
- Pins the Template’s current Version in the Startup’s lockfile.
- Refuses a clash between two bases until the Startup settles it.

## 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. | [Template.extend](/business/nouns/template/extend) |
| The record is not in a state that allows this Verb, so the call is refused. | [`refused`](/code/api/errors/refused) | Read the record, run the Verb that moves it to an allowed state, then retry. | [Template.extend](/business/nouns/template/extend) |
| A clash between two bases until the Startup settles it | [`refused`](/code/api/errors/refused) | Clear what the check names, then call it again. | [Template.extend](/business/nouns/template/extend) |

## 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
Extend the latest template with a startup.
```

**API**

```bash
curl -X POST https://api.sb/quietcopy.com/templates/template_1/extend \
  -H "Authorization: Bearer $STARTUP_BUILDER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"startup":"startup_1"}'
```

```json
{
  "api": "https://api.sb/quietcopy.com",
  "startup": {
    "$id": "https://api.sb/quietcopy.com/startups/startup_1",
    "$type": "Startup",
    "name": "QuietCopy"
  },
  "template": {
    "$id": "https://api.sb/quietcopy.com/templates/template_1",
    "$type": "Template",
    "body": "Example body"
  },
  "action": {
    "$id": "https://api.sb/quietcopy.com/actions/action_1",
    "operation": "Template.extend",
    "status": "done"
  },
  "links": {
    "self": "https://api.sb/quietcopy.com/actions/action_1"
  }
}
```

**SDK**

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

const { startup, template } = await $.Template.extend({ template: 'template_1', startup: 'startup_1' })
```

**CLI**

```bash
npx startup-builder do Template.extend --json '{"template":"template_1","startup":"startup_1"}'
```

**MCP**

```json
{
  "name": "do",
  "arguments": {
    "code": "return await $.Template.extend({ template: 'template_1', startup: 'startup_1' })"
  }
}
```