(async () => {
  const sleep = (ms) => new Promise(r => setTimeout(r, ms))
  const key = (type, code) => window.dispatchEvent(new KeyboardEvent(type, { code, bubbles: true }))
  const tap = async (code, ms) => { key('keydown', code); await sleep(ms); key('keyup', code); await sleep(60) }
  for (let i = 0; i < 40 && (window.__d2webMap === undefined || window.__d2webMap.tick < 5); i++) await sleep(250)
  const state = window.__d2webMap
  if (state === undefined) return { error: 'no scene state' }
  const snap = () => ({
    tick: state.tick, x: Math.round(state.x), y: Math.round(state.y), level: state.playerLevel,
    xp: state.playerXp, kills: state.kills, gold: state.gold, bag: state.bagItems,
    ground: state.groundItems, monsters: state.monstersNear ? state.monstersNear.length : null,
    quests: state.quests, hp: state.playerHp, mana: state.playerMana,
  })
  // Fight for a few seconds: walk and swing repeatedly.
  key('keydown', 'KeyD')
  for (let i = 0; i < 12; i++) await tap('Space', 220)
  key('keyup', 'KeyD')
  key('keydown', 'KeyS')
  for (let i = 0; i < 12; i++) await tap('Space', 220)
  key('keyup', 'KeyS')
  await sleep(600)
  const before = snap()
  key('keydown', 'KeyK'); await sleep(200); key('keyup', 'KeyK')
  await sleep(400)
  const savedAt = snap()
  key('keydown', 'KeyD'); await sleep(2000); key('keyup', 'KeyD')
  await sleep(600)
  const drifted = snap()
  key('keydown', 'KeyL'); await sleep(200); key('keyup', 'KeyL')
  await sleep(800)
  const after = snap()
  const gl = document.querySelector('#view').getContext('webgl2')
  return {
    before, savedAt, drifted, after,
    saves: state.saves, loads: state.loads, saveError: state.saveError,
    tickRate: state.tickRate, glError: gl ? gl.getError() : null, error: state.error ?? null,
    source: state.source ?? null, itemTablesSource: state.itemTablesSource ?? null,
  }
})()