injectDownload

injectDownload(): { download: DownloadFn }

type DownloadFn = (params: { contents: (EmbeddedResource | ResourceLink)[] })
  => Promise<{ isError?: boolean }>;

import { injectDownload } from "ng-mcp-ui/web";

export class ReportWidget {
  private readonly downloader = injectDownload();

  async save() {
    const result = await this.downloader.download({
      contents: [{ type: "resource_link", uri: this.url(), name: "report.pdf" }],
    });

    if (result.isError) {
      this.showLinkInstead();
    }
  }
}

It does not throw

The function always resolves. An unsupported host gives { isError: true }, and the adaptor writes a log message.

Therefore test the result. Do not use a try/catch block.

contents

Pass MCP content blocks: a ResourceLink for a URL, or an EmbeddedResource for inline data.

Build the blocks on the server with the content helpers, then read them in the view from injectToolInfo. Thus the view does not construct the shape by hand.

Host support

Host	Behavior
Apps SDK	Returns { isError: true }. The adaptor writes a log message.
MCP Apps	Supported, if the host advertises the downloadFile capability. Without it, the result is { isError: true }.

The capability test happens inside the adaptor. Your code only reads isError.

Always give a fallback. A link that the user can open with injectOpenExternal works on each host.

Related

• Files and downloads
• injectFiles
• Host support