# Slash Composer

> AI composer with a / command menu whose pick becomes a token the text wraps around, @ mentions that attach files and docs as chips, an Ask, Plan or Agent mode switch with a sliding pill, full keyboard control and a live context-size estimate.

- Slug: `slash-composer`
- Category: [AI chat](https://www.assembli.design/category/ai-chat.md)
- Type: component
- Tags: composer, slash-commands, mentions, input, agent
- npm dependencies: motion, lucide-react
- shadcn/ui dependencies: none
- Added: 2026-10-17
- Live preview: https://www.assembli.design/preview/slash-composer
- Page: https://www.assembli.design/components/slash-composer

## 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/slash-composer/slash-composer.tsx` and installs dependencies):

```bash
npx shadcn@latest add @assembli/slash-composer
```

Registry item JSON: https://www.assembli.design/r/slash-composer.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.