Write a plugin

Plugins are ESM modules that are dynamically imported at runtime. A plugin register function receives the Host API: window.__PLAY_HOST__.

Minimal example

This repo ships a small demo plugin you can load directly:

http://127.0.0.1:8000/index.html?model=raj&plugins=./plugins/test_ui_sections_plugin.mjs

The plugin exports registerPlayPlugin(host). It may also use a default export. The register function can return a disposer:

export function registerPlayPlugin(host) {
  const handle = host.ui.sections.register({
    panel: "left",
    sectionId: "plugin:hello",
    title: "Hello",
    defaultOpen: true,
    after: "file",
    render: (body) => {
      body.textContent = "Hello from plugin";
    },
  });
  return () => handle?.dispose?.();
}

Loading

Supported configurations:

• URL parameter: ?plugins=<url1>,<url2>

• Global. Must be set before the main module runs: globalThis.PLAY_PLUGINS = ['<url1>', '<url2>']

Worker boundary

In the default Worker backend, plugins cannot access WASM exports directly. Use:

• host.backend for commands

• snapshot streams: host.backend.subscribe(...) or host.clock.onSnapshot

For the full contract, see Plugin contract.