@natui/core/inproc

runEmbedded

function runEmbedded(
  element: ReactNode,
  options?: RunEmbeddedOptions,
): Promise<EmbeddedApp>

Mounts a React element inside an embedding native host and resolves after the first React commit. RunEmbeddedOptions includes the window property shape used by the protocol, plus onClose and a startup timeout override.

The host must provide:

• globalThis.__natui_send(json) for JavaScript-to-host messages
• A ready handshake with compatible protocol and host API levels after evaluating the bundle

The module installs globalThis.__natui_recv(json) for host-to-JavaScript messages. One embedded application may be active in a JavaScript runtime at a time. A second runEmbedded call rejects instead of replacing the active receive hook.

import { Text } from '@natui/core/components';
import { runEmbedded } from '@natui/core/inproc';

const app = await runEmbedded(<Text>Hello</Text>, {
  title: 'embedded NatUI',
  width: 400,
  height: 240,
  onClose() {
    console.log('Window close requested');
  },
});

app.update(<Text>Hello again</Text>);
app.quit();

EmbeddedApp

quit() is synchronous and idempotent. Its first call unmounts React, runs effect cleanup, sends one host quit message, rejects pending bridge work, and removes globalThis.__natui_recv. Calls after shutdown begins do nothing. update() throws after shutdown begins.

A native window close invokes onClose once and then uses the same shutdown path. A startup compatibility failure also requests host shutdown and detaches the receive hook.

The entrypoint contains no Node built-ins and targets browser-platform bundling. The repository implements this embedding contract with JavaScriptCore on macOS and V8 on Windows. Packaged applications use this same API. See application bundles.