XZBT-NGN/test-fixtures/reference-exhibits/museum-gallery/artifact.boot.js

/*
 * Museum Gallery — Artifact Display boot (non-primary surface).
 *
 * This document deliberately never loads contract-core.js, exhibit.js, or
 * contract-adapter.js. It has no way to construct an Exhibit State Core --
 * it can only attach to the one the Control Room document created, over
 * surface-bus.js. If the Control Room is not open, this degrades to a clear
 * waiting state rather than inventing its own state (Contract 5.3 Section
 * 31.8, Step 6.1 Section 7.2).
 */
(function () {
  'use strict';

  var Shell = window.XZBTShell;
  var el = Shell.el;
  var statusEl = el('status');
  var announcer = new Shell.Announcer({ node: el('announcement'), idleText: 'Waiting for shared state.' });
  var cycleButton = el('cycle-button');

  var ARTIFACT_ORDER = ['the-orrery', 'star-map', 'meteorite'];
  var ARTIFACT_LABELS = { 'the-orrery': 'The Orrery', 'star-map': 'Star Map', meteorite: 'Meteorite Fragment' };

  /* This is a read-only MIRROR of authoritative state, not a second copy of
   * exhibit state: it is discarded and re-seeded from a fresh snapshot on
   * every attach, and every write attempt is a mutate() call routed back
   * through the owner's canonical mutation path -- this document never
   * writes to `latest` in response to a user action, only in response to
   * a snapshot or an event relayed from the one Core. */
  var latest = null;

  function render() {
    if (!latest) return;
    Shell.setText(el('artifact-name'), ARTIFACT_LABELS[latest['artifact.selected']] || latest['artifact.selected']);
    Shell.setText(el('lighting-readout'), Shell.formatPercent(latest['lighting.level']));
    Shell.setText(el('rotation-readout'), latest['rotation.speed'].toFixed(1) + 'x');
  }

  var link = window.MuseumGallerySurfaceBus.attach({
    timeoutMs: 1500,
    onSnapshot: function (snapshot) {
      latest = snapshot.values;
      Shell.setText(statusEl, 'Attached to Control Room.');
      statusEl.classList.remove('is-waiting');
      cycleButton.disabled = false;
      render();
    },
    onEvent: function (event) {
      if (!latest) return;
      if (event.type === 'state.changed' || event.type === 'selection.changed') {
        latest[event.target] = event.value;
        render();
      } else if (event.type === 'action.executed' && event.target === 'action.spotlight-flash') {
        announcer.flash('Spotlight flashed.');
      }
    },
    onTimeout: function () {
      Shell.setText(statusEl, 'Waiting for the Control Room surface to be open…');
      statusEl.classList.add('is-waiting');
      cycleButton.disabled = true;
    }
  });

  cycleButton.addEventListener('click', function () {
    if (!latest) return;
    var idx = ARTIFACT_ORDER.indexOf(latest['artifact.selected']);
    var next = ARTIFACT_ORDER[(idx + 1) % ARTIFACT_ORDER.length];
    /* Routed to the owner's canonical mutation path -- this is the required
     * proof that a native interaction on a non-primary surface obeys the
     * same mutation/revision/source/event semantics as primary UI or a
     * contract set/invoke (Contract 5.3 Section 31.7). */
    link.mutate('set', 'artifact.selected', next);
  });

  /* `beforeunload` is best-effort only -- it does not reliably fire when
   * NGN removes/replaces this frame's iframe element directly (as opposed
   * to a real navigation), so it is not the correctness mechanism here.
   * `__xzbtSurfaceDispose` is a well-known, optional hook: local-surfaces.js
   * calls it synchronously, if present, on this frame's contentWindow right
   * before removing the iframe -- deterministic because it is a direct
   * same-origin call, not a queued postMessage that a doomed frame might
   * never get to process. detach() is idempotent, so it is safe for both
   * this hook and beforeunload to fire (or neither, or either alone). */
  window.__xzbtSurfaceDispose = function () { link.detach(); };
  window.addEventListener('beforeunload', function () { link.detach(); });
  window.__museumGalleryDebug = { link: link };
})();