Embedding & self-hosting assets

The heavy machinery (the kernel worker, its nested fs/fetcher/process workers, and the Rust/Wasm VFS + codec + crypto artifacts) is reached via new Worker(new URL(..., import.meta.url)) and new URL('*.wasm', import.meta.url). The published dist/ is self-contained: modern bundlers (Vite, webpack 5, Rollup, esbuild) resolve those relative to the installed package and emit them same-origin.

Because the page is under Cross-Origin-Embedder-Policy: require-corp, every asset must load same-origin (or send CORP/CORS). Two assets you must host yourself:

1. The preview Service Worker

Copy @vivari/core/dist/assets/sw.js to your served root as /sw.js (or point serviceWorkerUrl at your chosen path). It must be served with Service-Worker-Allowed: / so it can claim the /preview/<port>/ proxy prefix for the whole origin.

import { Vivari } from "@vivari/core";

const vivari = await Vivari.boot({
  serviceWorkerUrl: "/sw.js", // wherever you host it
});

2. Package-manager tarballs (optional)

Only if you run npm / yarn / pnpm in-VM. Vivari fetches vendored PM deliveries from /vendor/... on your origin; host that directory too, or skip installs.

Isolated previews need more

Those two are all you need for the default same-origin previews. If you set previewOrigin or previewWildcardDomain in BootOptions to isolate previews on their own origin, that origin has to serve its own copy of sw.js plus a bridge document — see Preview isolation modes.

Headers

Every HTML document that boots Vivari (and the sw.js script) needs:

Cross-Origin-Opener-Policy: same-origin
Cross-Origin-Embedder-Policy: require-corp

See Cross-origin isolation for host-specific recipes, and Deployment for the Cloudflare Pages _headers file this site uses.

A minimal Vite embedder

// vite.config.ts
import { defineConfig } from "vite";

const isolation = {
  "Cross-Origin-Opener-Policy": "same-origin",
  "Cross-Origin-Embedder-Policy": "require-corp",
};

export default defineConfig({
  server: { headers: isolation },
  preview: { headers: isolation },
  worker: { format: "es" },
});

Then copy node_modules/@vivari/core/dist/assets/sw.js into your public/ as sw.js, and you're ready to Vivari.boot().