# attach

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

> Attach matches a receipt File to a card Transaction, or flags the Transaction when no receipt arrives in time.

Attach matches a receipt [File](/business/nouns/file) to a card [Transaction](/business/nouns/transaction), or flags the Transaction when no receipt arrives in time.

## Inputs
| Input | Type | Required | Description |
| --- | --- | --- | --- |
| `transaction` | [Transaction](/business/nouns/transaction) | Yes | The card Transaction. |
| `file` | [File](/business/nouns/file) | No | The receipt; empty to match from the Startup’s Mailboxes. |

## Outputs
| Output | Type | Required | Description |
| --- | --- | --- | --- |
| `transaction` | [Transaction](/business/nouns/transaction) | Yes | The Transaction with its receipt. |

## Effects
- Emits [`Transaction.attached`](/business/events/Transaction.attached).
- Performed by the [Finance Lead](/agents/finance/finance-lead).
- Two-way: it runs at once, in the `try`, `send` and `do` modes.
- Reads receipts sent to the Startup’s Mailboxes and uploaded Files.
- After 7 days with no receipt, opens a Task for the Role whose Mandate spent.

## 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. | [Transaction.attach](/business/nouns/transaction/attach) |

## 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
Attach the latest transaction.
```

**API**

```bash
curl -X POST https://api.sb/ledgerlark.com/transactions/transaction_1/attach \
  -H "Authorization: Bearer $STARTUP_BUILDER_API_KEY"
```

```json
{
  "api": "https://api.sb/ledgerlark.com",
  "transaction": {
    "$id": "https://api.sb/ledgerlark.com/transactions/transaction_1",
    "$type": "Transaction",
    "kind": "charge",
    "amount": {
      "amount": 400,
      "currency": "USD"
    }
  },
  "action": {
    "$id": "https://api.sb/ledgerlark.com/actions/action_1",
    "operation": "Transaction.attach",
    "status": "done"
  },
  "links": {
    "self": "https://api.sb/ledgerlark.com/actions/action_1"
  }
}
```

**SDK**

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

const transaction = await $.Transaction.attach({ transaction: 'transaction_1' })
```

**CLI**

```bash
npx startup-builder do Transaction.attach --json '{"transaction":"transaction_1"}'
```

**MCP**

```json
{
  "name": "do",
  "arguments": {
    "code": "return await $.Transaction.attach({ transaction: 'transaction_1' })"
  }
}
```