# Comment Composer

> A comment thread with a reply box built from Autosize Textarea. The box grows as you write and stops at eight lines, a ring counts toward a soft limit, attach, mention and emoji tools sit in its footer, ⌘/Ctrl+Enter posts with a spinner while your async save runs, and the new comment slides into a fixed-height thread that scrolls to the newest reply.

- Slug: `comment-composer`
- Category: [Forms](https://www.assembli.design/category/forms.md)
- Type: component
- Tags: form, comment, reply, composer, textarea, thread
- npm dependencies: lucide-react
- shadcn/ui dependencies: @assembli/autosize-textarea
- Added: 2026-10-23
- Live preview: https://www.assembli.design/preview/comment-composer
- Page: https://www.assembli.design/components/comment-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/comment-composer/comment-composer.tsx` and installs dependencies):

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

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