# undo

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

> Undo reverses a done Action: it deletes the records the Action created and restores what it changed, each restorable.

Undo reverses a done [Action](/business/nouns/action): it deletes the records the Action created and restores what it changed, each restorable.

## Inputs
| Input | Type | Required | Description |
| --- | --- | --- | --- |
| `action` | [Action](/business/nouns/action) | Yes | The done Action to undo. |

## Outputs
| Output | Type | Required | Description |
| --- | --- | --- | --- |
| `action` | [Action](/business/nouns/action) | Yes | The undone Action, linked to the records it removed and restored. |

## Effects
| Fact | Value |
| --- | --- |
| Action class | None: it runs within its seat's Limits |
| Door | Two-way: it runs at once |
| Modes | `try` previews it and stores nothing; `send` returns a pending Action; `do` (default) waits for the result |
| Idempotent | With a key: a repeat with the same `Idempotency-Key` returns the first Action, and a repeat without one runs again |
| Undo | [Action.undo](/business/nouns/action/undo) reverses it |
| Emits | [`Action.undone`](/business/events/Action.undone) |

- Deletes each record the Action created as a soft delete, so `Thing.restore` brings it back.
- Money the Action moved returns through a new Action, such as a refund; a Transaction is never removed.
- A sent Message stays sent; undo records that it cannot unsend 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. | None. |

## 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
Undo the latest action.
```

**API**

```bash
curl -X POST https://api.sb/leaseline.app/actions/act_br07HsG8MG/undo \
  -H "Authorization: Bearer $STARTUP_BUILDER_API_KEY"
```

```json
{
  "api": "https://api.sb/leaseline.app",
  "action": {
    "$id": "https://api.sb/leaseline.app/actions/act_br07HsG8MG",
    "$type": "Action",
    "status": "done",
    "mode": "try",
    "operation": "Action.undo"
  },
  "links": {
    "self": "https://api.sb/leaseline.app/actions/act_br07HsG8MG"
  }
}
```

**SDK**

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

const action = await $.Action.undo({ action: 'act_br07HsG8MG' })
```

**CLI**

```bash
npx startup-builder do Action.undo --json '{"action":"act_br07HsG8MG"}'
```

**MCP**

```json
{
  "name": "do",
  "arguments": {
    "code": "return await $.Action.undo({ action: 'act_br07HsG8MG' })"
  }
}
```

Guides that call it: [Undo what the agent did](/agents/undo-what-the-agent-did).