# `CommitOptions.undo`

> Contract 2.0.0 · package sha256 `a857eca95b35921109faf997094bb4192f12527d9d0fcd4be7e97f06425bad6e` · generated from `configurator-runtime.d.ts` by `services/onsite-scripter/scripts/build-contract-docs.mjs`; edit the source, not this file.

Property of [`CommitOptions`](CommitOptions.md) · inherited by [`WriteOptions`](WriteOptions.md), [`TransactionOptions`](TransactionOptions.md) · stable · since 2.0.0

```ts
undo?: 'rebase' | (string & {});
```

An undo label makes this write one undo step. 'rebase' (a reserved label) records no step and
rebases history to the result: every earlier step, a shopper's included, can no longer be
undone, and redo is cleared, also when the write is equal (spec section 6.1, O15); on an empty
[`applyPatch([])`](Writer.applyPatch.md) it clears history with no change. Use it for a later load (a saved design
opened mid-session), or in an app that keeps its own undo; the session's first model is the
floor by itself. Camera writes are never undo steps.
Not for: keeping a sync out of history after shopper edits. Label the sync instead; a sync that
changes nothing commits nothing.

**Default:** a recorded-state change gets one step labelled 'Change'; a look-only write gets
none; the session's first model (cause 'load') gets none, whatever the label: it is the floor
of history

## Generic-API test (spec 3.1)

| Rule | Result |
| --- | --- |
| 1. Neutral name | pass: `undo` names no product |
| 2. A precedent | pass: [ProseMirror history (addToHistory)](https://prosemirror.net/docs/ref/#history) (row `K62`); [Unity Undo](https://docs.unity3d.com/ScriptReference/Undo.html) (row `K62`) |
| 3. Two apps, or labs | pass: 3 apps (ledger: app-04c2774145, app-4762caacdc, app-f9a32142f1) |
| 4. The cheaper fix first | decided per need in Appendix B: rows `K62` at tier stable (a member only where no rule, data, asset or app code serves the need) |