# Checkpoint Rewind

> Undo for an agent's work as a tape you can scrub: drag the playhead back and everything after it turns to hatching, with the checkpoints and files that would be reverted and their line counts. Restore is press-and-hold so a stray click never throws work away.

- Slug: `checkpoint-rewind`
- Category: [AI chat](https://www.assembli.design/category/ai-chat.md)
- Type: component
- Tags: agent, undo, checkpoints, timeline, restore
- npm dependencies: motion, lucide-react
- shadcn/ui dependencies: none
- Added: 2026-10-17
- Live preview: https://www.assembli.design/preview/checkpoint-rewind
- Page: https://www.assembli.design/components/checkpoint-rewind

## Install

One-time setup (needs a subscription):

1. Add the registry to the project's `components.json`: `{"@assembli":{"url":"https://www.assembli.design/r/{name}.json","headers":{"Authorization":"Bearer ${ASSEMBLI_API_KEY}"}}}` (merge into `"registries"`).
2. Put an API key from https://www.assembli.design/account in `.env.local` as `ASSEMBLI_API_KEY=asm_…`.

Then install with the shadcn CLI (writes `components/checkpoint-rewind/checkpoint-rewind.tsx` and installs dependencies):

```bash
npx shadcn@latest add @assembli/checkpoint-rewind
```

Registry item JSON: https://www.assembli.design/r/checkpoint-rewind.json (send `Authorization: Bearer <api key>`)

## Code

> Component source needs an Assembli subscription ($12/month) and an API key sent as `Authorization: Bearer <key>`. To get one without copying anything, POST https://www.assembli.design/api/agent/login (or call the MCP tool connect_account), show the user the link it returns, and poll https://www.assembli.design/api/agent/token for the key. Or subscribe at https://www.assembli.design/pricing and create a key at https://www.assembli.design/account.