# merge

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

> Merge applies a Change to live data with a three-way, field-level merge against its base Version.

Merge applies a [Change](/business/nouns/change) to live data with a three-way, field-level merge against its base [Version](/business/nouns/version).

## Inputs
| Input | Type | Required | Description |
| --- | --- | --- | --- |
| `change` | [Change](/business/nouns/change) | Yes | The reviewed Change. |

## Outputs
| Output | Type | Required | Description |
| --- | --- | --- | --- |
| `version` | [Version](/business/nouns/version) | Yes | The new Version. |
| `change` | [Change](/business/nouns/change) | Yes | The Change, now merged into live data. |

## Effects
- Emits [`Change.merged`](/business/events/Change.merged).
- Performed by the [Engineering Lead](/agents/engineering/engineering-lead).
- Sends the Change back to review when a field changed on both sides since its base.
- Never overwrites a concurrent edit.

## 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. | [Change.merge](/business/nouns/change/merge) |
| The record changed since it was read, so the write would overwrite a newer version. | [`conflict`](/code/api/errors/conflict) | Read the record again, then retry the write against its current state. | [Change.merge](/business/nouns/change/merge) |
| 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. | [Change.merge](/business/nouns/change/merge) |

## 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
Merge the latest change.
```

**API**

```bash
curl -X POST https://api.sb/tutorloop.com/changes/change_1/merge \
  -H "Authorization: Bearer $STARTUP_BUILDER_API_KEY"
```

```json
{
  "api": "https://api.sb/tutorloop.com",
  "version": {
    "$id": "https://api.sb/tutorloop.com/versions/version_1",
    "$type": "Version",
    "fingerprint": "sha256:9f2c4e1a7b3d"
  },
  "change": {
    "$id": "https://api.sb/tutorloop.com/changes/change_1",
    "$type": "Change",
    "status": "Merged",
    "base": "version_1"
  },
  "action": {
    "$id": "https://api.sb/tutorloop.com/actions/action_1",
    "operation": "Change.merge",
    "status": "done"
  },
  "links": {
    "self": "https://api.sb/tutorloop.com/actions/action_1"
  }
}
```

**SDK**

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

const { version, change } = await $.Change.merge({ change: 'change_1' })
```

**CLI**

```bash
npx startup-builder do Change.merge --json '{"change":"change_1"}'
```

**MCP**

```json
{
  "name": "do",
  "arguments": {
    "code": "return await $.Change.merge({ change: 'change_1' })"
  }
}
```

Next: [`Version.deploy`](/business/nouns/version/deploy) (in `guide:ship-my-changes`).

Guides that call it: [Ship my changes](/code/ship-my-changes).