> ## Documentation Index
> Fetch the complete documentation index at: https://docs.automate.ax/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Automate.ax automations are TypeScript programs.
> Use Bun for installation and command examples.
> Use Automate.ax for the product name and automate.ax for the package, CLI, and domain.
> Treat documented public APIs as current; do not invent transitional or deprecated names.

# Add attachment

> Attach a public URL to a Trello card.

`addAttachment` adds a URL attachment and can use it as the card cover. It does not upload local file bytes.

```ts automations/attach-trello-link.automation.ts theme={null}
import { automation, onHttpRequest } from "automate.ax"
import { addAttachment } from "automate.ax/trello"

export default automation("Attach release notes", () => {
  onHttpRequest({ scope: "automation" })
  addAttachment({
    card: "card-id",
    url: "https://automate.ax/releases/1",
    name: "Release notes",
    setCover: false,
  })
})
```

`card` and valid public `url` are required. Optional `name` sets the display label; `setCover` defaults to `false`; `account` defaults to the project binding.

Returns `Signal<TrelloAttachment>` with `id`, `name`, `url`, `createdAt`, `position`, `isUpload`, and nullable `bytes` and `mimeType`. Keep `id` for deletion.