export async function startP1(api, inlineFixture) {
  const data = inlineFixture ?? await new api.JsonOrgChartDataSource('./data-p1.json').load();
  const stylesheetUrls = {
    engine: new URL('./assets/engine.css', location.href).href,
    core: new URL('./assets/style.css', location.href).href,
  };
  // ?mode=readOnly shows the view-only Workdesk composition; the default stays interactive.
  const displayMode = new URLSearchParams(location.search).get('mode') === 'readOnly' ? 'readOnly' : 'interactive';
  document.documentElement.dataset.orgchartMode = displayMode;
  const chart = api.createOrgChart({ container: document.getElementById('chart-host'), dataSource: new api.JsonOrgChartDataSource(data), stylesheetUrls, displayMode });
  // Development inspection seam: public Core API only. No engine internals.
  window.OrgChartP1 = { api, data, chart, stylesheetUrls, setData: next => chart.update(next) };
  window.addEventListener('pagehide', () => chart.destroy(), { once: true });
  await chart.mount();
}