@datalayer/reactor-shell

The shell plugin other plugins extend. A shell — a workspace, a store, a CMS — usually has one control whose options come from everybody else: which editor, which panel, which mode. This plugin is that control made generic.

import { buildReactorFromPlugins, contribution } from '@datalayer/reactor';
import { ShellPlugin, ShellView } from '@datalayer/reactor-shell';

const NotebookPlugin = definePlugin({
  name: '@me/notebook',
  contributes: [
    contribution(ShellView, {
      id: 'notebook',
      title: 'Notebook',
      order: 10,
    }),
  ],
});

const reactor = buildReactorFromPlugins([ShellPlugin, NotebookPlugin]);

It owns four things:

• A view point — its own ShellView by default, or one the host already declared, passed through config.point. Contributions are what populate everything else.
• A segmented selector that renders into a slot (config.slot) and shows nothing at all until a plugin contributes: an empty application is an empty control, not a fake one. A view that cannot open right now stays focusable and says why (aria-disabled plus a title), rather than disappearing.
• A choice store (chooseView, getViewChoice, subscribeViewChoice, nextView) that commands can read and cycle from outside React.
• A cycle command in the reactor's registry, Mod+Alt+E by default — reachable from the command palette like everything else.

What a chosen view does is the host's business: every choice goes through the configurable announce callback, whose return value says whether anyone was listening — a command invoked with nobody on the other end says so rather than appearing to work.

Configuration

Option	Default	What it does
point	ShellView	The contribution point the views arrive through
describe	identity	Maps a contributed value (+ the slot's props as context) to { id, title, icon?, order?, disabled?, disabledReason? }
slot	'header'	Where the selector renders
defaultView	'none'	Seeded into the store, not announced
showSelector	true	The control; the store and command remain either way
allowNone	true	Whether "none" is a choice. false for a host whose views are the whole application: the selector then lists only the views, appears only once there are two, and the cycle command wraps among them
announce	() => true	Told of every choice; returns whether anyone heard
commandId, keybinding	shell.cycleView, Mod+Alt+E	The cycle command
noneLabel, ariaLabel	None, View	Words

Grown from Loop

This plugin is the LOOP workspace's editor selector, generalised. The loop's own shell plugin in @datalayer/agent-runtimes is now a thin wrapper: it points config.point at the loop's editor contribution point, describe gates each editor against the live workspace, and announce forwards the choice to the chat's surface-request channel. The Loop documentation describes that composition.