const $ = (id) => document.getElementById(id);

const statusEl = $("status");
const imageEl = $("image");
const canvasEl = $("image-canvas");
const placeholderEl = $("placeholder");
const downloadGateEl = $("download-gate");
const downloadGateTitleEl = $("download-gate-title");
const startDownloadButton = $("start-download");
const actionsEl = $("actions");
const runButton = $("run");
const warmButton = $("warm");
const abortButton = $("abort");
const elapsedEl = $("elapsed");
const initImageInput = $("init-image");
const initImageLabelEl = $("init-image-label");
const clearInitImageButton = $("clear-init-image");
const sourcePreviewWrap = $("source-preview-wrap");
const sourcePreviewEl = $("source-preview");
const sourceMetaEl = $("source-meta");
const img2imgControlsEl = $("img2img-controls");
const strengthEl = $("strength");
const strengthCurveEl = $("strength-curve");
const strengthValueEl = $("strength-value");
const resolutionPresetEl = $("resolution-preset");
const resolutionAdvancedEl = $("resolution-advanced");
const aspectLockButton = $("aspect-lock");
const aspectLockIconEl = $("aspect-lock-icon");
const aspectRatioEl = $("aspect-ratio");
const settingsToggleButton = $("settings-toggle");
const settingsPopoverEl = $("settings-popover");
const themeToggleButton = $("theme-toggle");
const themeIconEl = $("theme-icon");
const galleryPanelEl = $("gallery-panel");
const galleryGridEl = $("gallery-grid");
const clearGalleryButton = $("clear-gallery");
const loadProgressEl = $("load-progress");
const loadProgressTitleEl = $("load-progress-title");
const loadProgressSummaryEl = $("load-progress-summary");
const loadProgressTrackEl = $("load-progress-track");
const loadProgressFillEl = $("load-progress-fill");
const loadProgressDetailEl = $("load-progress-detail");
const loadProgressRateEl = $("load-progress-rate");
const urlDefaults = new URLSearchParams(window.location.search);
const DEFAULT_PROMPT = "A small ceramic robot on a workbench, product photo lighting";
const COMMON_RESOLUTIONS = [256, 512, 768, 1024];
const ASPECT_RATIOS = {
  "1:1": 1,
  "4:3": 4 / 3,
  "3:4": 3 / 4,
  "16:9": 16 / 9,
  "9:16": 9 / 16,
};
const THEME_STORAGE_KEY = "flux2-static-theme";
const GALLERY_LIMIT = 24;
const DEFAULT_LOCAL_MODEL_BASE_URL = "/models";
const DEFAULT_LOCAL_RUNTIME_BASE_URL = "/runtime";
const BACKEND_DOWNLOADS = {
  "custom-lowbit-webgpu": {
    title: "Download model assets (3.5 GB)",
    status: "Model assets: 3.5 GB",
  },
  "onnx-webgpu": {
    title: "Download ONNX WebGPU assets (5.2 GB)",
    status: "ONNX WebGPU assets: 5.2 GB",
  },
};

let tokenizerPromise = null;
let transformersModulePromise = null;
let engineReadyPromise = null;
let engineModulePromise = null;
let customRuntimeScriptsPromise = null;
let currentImageUrl = null;
let currentSourceUrl = null;
let backgroundWarmPromise = null;
let backgroundWarmKey = "";
let backgroundWarmResultKey = "";
let backgroundWarmResult = null;
let foregroundBusy = false;
let warmScheduleTimer = 0;
let runTimerId = 0;
let runTimerStarted = 0;
let runTimerFinalized = true;
let aspectLockEnabled = true;
let aspectLockRatio = 1;
let aspectSyncing = false;
let generationHistory = [];
let backgroundAssetPreparePromise = null;
let backgroundAssetPrepareKey = "";
let backgroundTextContextPreparePromise = null;
let backgroundTextContextPrepareKey = "";
let backgroundTransformerSetupPreparePromise = null;
let backgroundTransformerSetupPrepareKey = "";
let backgroundVaePreparePromise = null;
let backgroundVaePrepareKey = "";
let backgroundVaeEncoderPreparePromise = null;
let backgroundVaeEncoderPrepareKey = "";
let backgroundDeepPrepareTimer = 0;
let backgroundDeepPrepareToken = 0;
let bootStarted = false;
let bootReady = false;
const preparedInitImageCache = new WeakMap();
const generationResultCache = new Map();
const tokenizedPromptCache = new Map();
const nativeFetch = globalThis.fetch.bind(globalThis);

const loadProgressState = {
  visible: false,
  tracking: false,
  completed: false,
  startedAt: 0,
  title: "Loading",
  detail: "Starting",
  estimatedTotalBytes: 0,
  estimatedFiles: 0,
  nextRequestId: 1,
  requests: new Map(),
  renderQueued: false,
  timerId: 0,
  hideTimerId: 0,
};

function formatMiB(bytes) {
  const value = Number(bytes || 0);
  return `${(value / (1024 * 1024)).toFixed(value >= 100 * 1024 * 1024 ? 0 : 1)} MiB`;
}

function formatBytesCompact(bytes) {
  const value = Number(bytes || 0);
  if (!Number.isFinite(value) || value <= 0) return "0 B";
  if (value >= 1024 ** 3) return `${(value / 1024 ** 3).toFixed(value >= 10 * 1024 ** 3 ? 1 : 2)} GiB`;
  if (value >= 1024 ** 2) return `${(value / 1024 ** 2).toFixed(value >= 100 * 1024 ** 2 ? 0 : 1)} MiB`;
  if (value >= 1024) return `${(value / 1024).toFixed(value >= 100 * 1024 ? 0 : 1)} KiB`;
  return `${Math.round(value)} B`;
}

function trimTrailingSlash(value) {
  return String(value || "").replace(/\/+$/, "");
}

function withTrailingSlash(value) {
  const text = String(value || "");
  return text.endsWith("/") ? text : `${text}/`;
}

function configString(name) {
  const value = globalThis[name];
  return typeof value === "string" && value.trim() ? value.trim() : "";
}

function currentUrlDefaults() {
  return new URLSearchParams(window.location.search);
}

function appAssetVersion() {
  return currentUrlDefaults().get("cacheBust") || "20260606-backend-download-gate";
}

function configuredModelBaseUrl() {
  const params = currentUrlDefaults();
  return trimTrailingSlash(
    params.get("modelBase") ||
    params.get("modelBaseUrl") ||
    configString("FLUX2_MODEL_BASE_URL") ||
    DEFAULT_LOCAL_MODEL_BASE_URL
  );
}

function configuredRuntimeBaseUrl(modelBaseUrl = configuredModelBaseUrl()) {
  const params = currentUrlDefaults();
  return trimTrailingSlash(
    params.get("runtimeBase") ||
    params.get("runtimeBaseUrl") ||
    configString("FLUX2_RUNTIME_BASE_URL") ||
    (modelBaseUrl === DEFAULT_LOCAL_MODEL_BASE_URL ? DEFAULT_LOCAL_RUNTIME_BASE_URL : modelBaseUrl)
  );
}

function configuredCustomKernelBaseUrl(modelBaseUrl = configuredModelBaseUrl(), runtimeBaseUrl = configuredRuntimeBaseUrl(modelBaseUrl)) {
  const params = currentUrlDefaults();
  return trimTrailingSlash(
    params.get("customKernelBase") ||
    params.get("customKernelBaseUrl") ||
    configString("FLUX2_CUSTOM_KERNEL_BASE_URL") ||
    (modelBaseUrl === DEFAULT_LOCAL_MODEL_BASE_URL ? `${runtimeBaseUrl}/custom_lowbit` : `${modelBaseUrl}/custom_lowbit`)
  );
}

function resolveAssetUrl(baseUrl, path) {
  return new URL(path, new URL(withTrailingSlash(baseUrl), window.location.href)).toString();
}

function compactLoadUrlLabel(url) {
  try {
    const parsed = new URL(url, window.location.href);
    const parts = parsed.pathname.split("/").filter(Boolean);
    const tail = parts.slice(-3).join("/");
    return tail || parsed.hostname;
  } catch {
    return String(url || "download");
  }
}

function beginLoadProgress(title = "Loading") {
  if (!loadProgressEl) return;
  if (loadProgressState.hideTimerId) {
    clearTimeout(loadProgressState.hideTimerId);
    loadProgressState.hideTimerId = 0;
  }
  loadProgressState.visible = true;
  loadProgressState.tracking = true;
  loadProgressState.completed = false;
  loadProgressState.startedAt = performance.now();
  loadProgressState.title = title;
  loadProgressState.detail = "Starting";
  loadProgressState.estimatedTotalBytes = 0;
  loadProgressState.estimatedFiles = 0;
  loadProgressState.nextRequestId = 1;
  loadProgressState.requests.clear();
  loadProgressEl.hidden = false;
  if (loadProgressState.timerId) clearInterval(loadProgressState.timerId);
  loadProgressState.timerId = setInterval(renderLoadProgress, 250);
  renderLoadProgress();
}

function setLoadPhase(detail, title = "") {
  if (!loadProgressState.visible) return;
  if (title) loadProgressState.title = title;
  if (detail) loadProgressState.detail = detail;
  scheduleLoadProgressRender();
}

function setLoadEstimate(totalBytes, expectedFiles = 0) {
  if (!loadProgressState.visible) return;
  const bytes = Number(totalBytes || 0);
  if (Number.isFinite(bytes) && bytes > loadProgressState.estimatedTotalBytes) {
    loadProgressState.estimatedTotalBytes = bytes;
  }
  const files = Number(expectedFiles || 0);
  if (Number.isFinite(files) && files > loadProgressState.estimatedFiles) {
    loadProgressState.estimatedFiles = files;
  }
  scheduleLoadProgressRender();
}

function finishLoadProgress(detail = "Ready", success = true) {
  if (!loadProgressState.visible) return;
  loadProgressState.tracking = false;
  loadProgressState.completed = success;
  if (!success) loadProgressState.title = detail;
  loadProgressState.detail = detail;
  if (success) {
    const loaded = loadProgressTotals().loaded;
    loadProgressState.estimatedTotalBytes = Math.max(loadProgressState.estimatedTotalBytes, loaded);
  }
  if (loadProgressState.timerId) {
    clearInterval(loadProgressState.timerId);
    loadProgressState.timerId = 0;
  }
  renderLoadProgress();
  if (success) {
    loadProgressState.hideTimerId = setTimeout(() => {
      loadProgressState.visible = false;
      if (loadProgressEl) loadProgressEl.hidden = true;
    }, 4500);
  }
}

function loadProgressTotals() {
  let loaded = 0;
  let dynamicTotal = 0;
  let active = 0;
  let completed = 0;
  let failed = 0;
  let current = "";
  for (const request of loadProgressState.requests.values()) {
    loaded += request.loaded || 0;
    if (request.total) dynamicTotal += request.total;
    if (request.failed) failed += 1;
    if (request.done || request.failed) {
      completed += 1;
    } else {
      active += 1;
      current = request.label || current;
    }
  }
  return {
    loaded,
    total: Math.max(loadProgressState.estimatedTotalBytes, dynamicTotal, loaded),
    active,
    completed,
    failed,
    current,
  };
}

function renderLoadProgress() {
  if (!loadProgressEl || !loadProgressState.visible) return;
  loadProgressState.renderQueued = false;
  const { loaded, total, active, completed, failed, current } = loadProgressTotals();
  const elapsed = Math.max(0.001, (performance.now() - loadProgressState.startedAt) / 1000);
  const rate = loaded / elapsed;
  const hasTotal = total > 0;
  const percent = hasTotal ? Math.max(0, Math.min(100, (loaded / total) * 100)) : 0;
  const displayPercent = hasTotal && loadProgressState.tracking && active > 0
    ? Math.min(percent, 99.5)
    : percent;
  const files = loadProgressState.estimatedFiles
    ? `${Math.min(completed, loadProgressState.estimatedFiles)}/${loadProgressState.estimatedFiles} files`
    : `${completed}${active ? ` +${active}` : ""} files`;
  const summary = !loadProgressState.tracking && !loadProgressState.completed
    ? "Error"
    : loadProgressState.completed
    ? "Ready"
    : hasTotal
      ? `${displayPercent.toFixed(displayPercent >= 10 ? 0 : 1)}%`
      : "Loading";
  const detailParts = [
    hasTotal ? `${formatBytesCompact(loaded)} / ${formatBytesCompact(total)}` : `${formatBytesCompact(loaded)} downloaded`,
    files,
    failed ? `${failed} failed` : "",
    current || loadProgressState.detail,
  ].filter(Boolean);
  loadProgressTitleEl.textContent = loadProgressState.title;
  loadProgressSummaryEl.textContent = summary;
  loadProgressDetailEl.textContent = detailParts.join(" | ");
  loadProgressRateEl.textContent = `${formatBytesCompact(rate)}/s | ${elapsed.toFixed(1)}s`;
  loadProgressTrackEl.classList.toggle("indeterminate", !hasTotal && loadProgressState.tracking);
  loadProgressFillEl.style.width = hasTotal ? `${loadProgressState.completed ? 100 : displayPercent}%` : "";
}

function scheduleLoadProgressRender() {
  if (!loadProgressState.visible || loadProgressState.renderQueued) return;
  loadProgressState.renderQueued = true;
  requestAnimationFrame(renderLoadProgress);
}

function shouldTrackLoadFetch(input, init, response) {
  if (!loadProgressState.tracking || !response || !response.body) return false;
  const method = String(init?.method || (input && typeof input === "object" && input.method) || "GET").toUpperCase();
  if (method !== "GET") return false;
  return true;
}

function trackLoadFetch(input, response) {
  const url = response.url || (typeof input === "string" ? input : input?.url) || "";
  const totalHeader = response.headers.get("content-length");
  const total = totalHeader ? Number(totalHeader) : 0;
  const id = loadProgressState.nextRequestId++;
  const request = {
    id,
    url,
    label: compactLoadUrlLabel(url),
    total: Number.isFinite(total) && total > 0 ? total : 0,
    loaded: 0,
    done: false,
    failed: false,
  };
  loadProgressState.requests.set(id, request);
  scheduleLoadProgressRender();

  const reader = response.body.getReader();
  const stream = new ReadableStream({
    async pull(controller) {
      try {
        const { done, value } = await reader.read();
        if (done) {
          request.done = true;
          scheduleLoadProgressRender();
          controller.close();
          return;
        }
        request.loaded += value.byteLength || value.length || 0;
        scheduleLoadProgressRender();
        controller.enqueue(value);
      } catch (err) {
        request.failed = true;
        scheduleLoadProgressRender();
        controller.error(err);
      }
    },
    cancel(reason) {
      request.done = true;
      scheduleLoadProgressRender();
      return reader.cancel(reason);
    },
  });

  return new Response(stream, {
    status: response.status,
    statusText: response.statusText,
    headers: response.headers,
  });
}

function installLoadProgressFetch() {
  if (globalThis.__flux2LoadProgressFetchInstalled) return;
  globalThis.__flux2LoadProgressFetchInstalled = true;
  globalThis.fetch = async (input, init) => {
    const response = await nativeFetch(input, init);
    if (!shouldTrackLoadFetch(input, init, response)) return response;
    return trackLoadFetch(input, response);
  };
}

function huggingFaceResolveSpec(baseUrl) {
  let url;
  try {
    url = new URL(baseUrl);
  } catch {
    return null;
  }
  if (!/^https?:$/i.test(url.protocol)) return null;
  if (!/^(huggingface\.co|hf\.co)$/i.test(url.hostname)) return null;
  const parts = url.pathname.split("/").filter(Boolean);
  const resolveIndex = parts.indexOf("resolve");
  if (resolveIndex < 2 || resolveIndex + 1 >= parts.length) return null;
  return {
    repoId: `${parts[0]}/${parts[1]}`,
    revision: decodeURIComponent(parts[resolveIndex + 1]),
  };
}

function tokenizerLoadSpec(modelBaseUrl) {
  const hfSpec = huggingFaceResolveSpec(modelBaseUrl);
  if (hfSpec) {
    return {
      source: hfSpec.repoId,
      remote: true,
      options: {
        local_files_only: false,
        revision: hfSpec.revision || "main",
      },
    };
  }
  const remote = /^https?:\/\//i.test(modelBaseUrl);
  return {
    source: remote ? resolveAssetUrl(modelBaseUrl, "tokenizer") : "models/tokenizer",
    remote,
    options: {
      local_files_only: !remote,
    },
  };
}

function setStatus(lines, isError = false) {
  const text = Array.isArray(lines) ? lines.filter(Boolean).join("\n") : String(lines);
  statusEl.textContent = text;
  statusEl.classList.toggle("error", Boolean(isError));
}

function setButtonDisabled(button, disabled) {
  if (button) button.disabled = disabled;
}

function setElapsed(text, active = false) {
  if (!elapsedEl) return;
  elapsedEl.textContent = text;
  elapsedEl.classList.toggle("active", active);
}

function setActionsVisible(visible) {
  if (actionsEl) actionsEl.hidden = !visible;
}

function setDownloadGateVisible(visible) {
  if (downloadGateEl) downloadGateEl.hidden = !visible;
}

function canRunRuntimeWork() {
  return bootStarted;
}

function selectedDownloadInfo() {
  return BACKEND_DOWNLOADS[$("backend")?.value] || BACKEND_DOWNLOADS["custom-lowbit-webgpu"];
}

function updateDownloadGateText() {
  const info = selectedDownloadInfo();
  if (downloadGateTitleEl) downloadGateTitleEl.textContent = info.title;
  return info;
}

function showDownloadGate({ retry = false, preserveStatus = false } = {}) {
  bootReady = false;
  const info = updateDownloadGateText();
  setDownloadGateVisible(true);
  setActionsVisible(false);
  if (startDownloadButton) startDownloadButton.disabled = false;
  runButton.disabled = true;
  setButtonDisabled(warmButton, true);
  abortButton.disabled = true;
  setElapsed("0.0s");
  placeholderEl.hidden = false;
  placeholderEl.textContent = "Model not loaded";
  if (!preserveStatus) {
    setStatus([
      retry ? "Download failed" : "Ready to download",
      info.status,
    ], retry);
  }
}

function showRuntimeLoading() {
  updateDownloadGateText();
  setDownloadGateVisible(false);
  setActionsVisible(false);
  if (startDownloadButton) startDownloadButton.disabled = true;
  runButton.disabled = true;
  setButtonDisabled(warmButton, true);
  abortButton.disabled = true;
  setElapsed("0.0s");
  placeholderEl.hidden = false;
  placeholderEl.textContent = "Loading";
}

function showRuntimeReady() {
  bootReady = true;
  setDownloadGateVisible(false);
  setActionsVisible(true);
  runButton.disabled = false;
  setButtonDisabled(warmButton, false);
  abortButton.disabled = true;
}

function updateRunTimer(prefix = "Generating") {
  if (!runTimerStarted) {
    setElapsed("0.0s");
    return 0;
  }
  const seconds = (performance.now() - runTimerStarted) / 1000;
  setElapsed(`${prefix} ${seconds.toFixed(1)}s`, true);
  return seconds;
}

function startRunTimer() {
  if (runTimerId) clearInterval(runTimerId);
  runTimerStarted = performance.now();
  runTimerFinalized = false;
  updateRunTimer();
  runTimerId = setInterval(() => updateRunTimer(), 100);
}

function finishRunTimer(label = "Done") {
  if (runTimerFinalized) return;
  const seconds = runTimerStarted ? (performance.now() - runTimerStarted) / 1000 : 0;
  if (runTimerId) clearInterval(runTimerId);
  runTimerId = 0;
  runTimerStarted = 0;
  runTimerFinalized = true;
  setElapsed(`${label} ${seconds.toFixed(2)}s`, false);
}

function setSettingsPopoverOpen(open) {
  if (!settingsPopoverEl || !settingsToggleButton) return;
  settingsPopoverEl.hidden = !open;
  settingsToggleButton.setAttribute("aria-expanded", open ? "true" : "false");
}

function seedLineForRequest(request) {
  if (!request) return "";
  return `Seed: ${request.seed}${Number(request.requestedSeed) < 0 ? " (random from -1)" : ""}`;
}

function seedInputLine() {
  const requestedSeed = Number($("seed").value);
  return Number.isFinite(requestedSeed) && requestedSeed >= 0
    ? `Seed: ${Math.trunc(requestedSeed)}`
    : "Seed: -1 (random)";
}

function seedLineForResult(result, request) {
  const seed = result?.seed ?? request?.seed;
  if (seed === undefined || seed === null) return "";
  return `Seed: ${seed}${request && Number(request.requestedSeed) < 0 ? " (random from -1)" : ""}`;
}

function captureDisplayedImageDataUrl() {
  try {
    if (!canvasEl.hidden && canvasEl.width && canvasEl.height) {
      return canvasEl.toDataURL("image/png");
    }
  } catch {
  }
  if (!imageEl.hidden && imageEl.src && !imageEl.src.startsWith("blob:")) return imageEl.src;
  return "";
}

function galleryItemFromResult(result, elapsed, request, heading = "") {
  const dataUrl = captureDisplayedImageDataUrl();
  if (!dataUrl || !request) return null;
  return {
    id: `${Date.now()}-${Math.random().toString(16).slice(2)}`,
    imageUrl: dataUrl,
    prompt: request.prompt,
    seed: result.seed ?? request.seed,
    requestedSeed: request.requestedSeed,
    width: result.width || request.width,
    height: result.height || request.height,
    steps: request.numSteps,
    backend: request.transformerBackend,
    speedProfile: request.speed?.requestedProfile || $("speed-profile").value,
    speedLabel: speedProfileLabel(request.speed || {}),
    mode: result.mode || (request.hasInitImage ? "image-to-image" : "text-to-image"),
    elapsed,
    heading,
    createdAt: new Date().toLocaleTimeString([], { hour: "numeric", minute: "2-digit", second: "2-digit" }),
  };
}

function renderGallery() {
  if (!galleryPanelEl || !galleryGridEl) return;
  galleryPanelEl.hidden = generationHistory.length === 0;
  galleryGridEl.innerHTML = "";
  for (const item of generationHistory) {
    const card = document.createElement("article");
    card.className = "gallery-card";
    card.dataset.galleryId = item.id;

    const image = document.createElement("img");
    image.src = item.imageUrl;
    image.alt = `Generated image seed ${item.seed}`;
    card.appendChild(image);

    const body = document.createElement("div");
    body.className = "gallery-body";
    const meta = document.createElement("div");
    meta.className = "gallery-meta";
    const prompt = document.createElement("div");
    prompt.className = "gallery-prompt";
    prompt.textContent = item.prompt || "(empty prompt)";
    const seed = document.createElement("div");
    seed.textContent = `Seed ${item.seed}${Number(item.requestedSeed) < 0 ? " random" : ""}`;
    const details = document.createElement("div");
    details.textContent = `${item.width} x ${item.height} · ${item.steps} steps · ${item.createdAt}`;
    meta.append(prompt, seed, details);

    const actions = document.createElement("div");
    actions.className = "gallery-actions";
    [
      ["prompt", "Prompt"],
      ["seed", "Seed"],
      ["reuse", "Reuse"],
      ["img2img", "Img2img"],
    ].forEach(([action, label]) => {
      const button = document.createElement("button");
      button.type = "button";
      button.className = "secondary";
      button.dataset.galleryAction = action;
      button.dataset.galleryId = item.id;
      button.textContent = label;
      actions.appendChild(button);
    });

    body.append(meta, actions);
    card.appendChild(body);
    galleryGridEl.appendChild(card);
  }
}

function rememberGalleryResult(result, elapsed, request, heading = "") {
  const item = galleryItemFromResult(result, elapsed, request, heading);
  if (!item) return;
  generationHistory = [item, ...generationHistory].slice(0, GALLERY_LIMIT);
  renderGallery();
}

async function dataUrlToFile(dataUrl, filename) {
  const response = await fetch(dataUrl);
  const blob = await response.blob();
  return new File([blob], filename, { type: blob.type || "image/png" });
}

async function setInitImageFromGallery(item) {
  const file = await dataUrlToFile(item.imageUrl, `history-seed-${item.seed}.png`);
  const transfer = new DataTransfer();
  transfer.items.add(file);
  initImageInput.files = transfer.files;
  initImageInput.dispatchEvent(new Event("change", { bubbles: true }));
}

function applyGalleryPrompt(item) {
  $("prompt").value = item.prompt || "";
  scheduleAutoWarmForCurrentSettings(650);
}

function applyGallerySeed(item) {
  $("seed").value = String(item.seed);
  scheduleAutoWarmForCurrentSettings(350);
}

function applyGallerySettings(item) {
  applyGalleryPrompt(item);
  applyGallerySeed(item);
  $("steps").value = String(item.steps || 4);
  $("width").value = String(item.width || 256);
  $("height").value = String(item.height || 256);
  syncResolutionPresetFromDimensions({ showAdvancedForCustom: true });
  setSelectValue("backend", item.backend);
  setSelectValue("speed-profile", item.speedProfile);
  scheduleAutoWarmForCurrentSettings(350);
}

function storedTheme() {
  try {
    return localStorage.getItem(THEME_STORAGE_KEY) || "";
  } catch {
    return "";
  }
}

function persistTheme(theme) {
  try {
    localStorage.setItem(THEME_STORAGE_KEY, theme);
  } catch {
  }
}

function applyTheme(theme, options = {}) {
  const nextTheme = theme === "light" ? "light" : "dark";
  document.documentElement.dataset.theme = nextTheme;
  if (themeIconEl) themeIconEl.textContent = nextTheme === "dark" ? "light_mode" : "dark_mode";
  if (themeToggleButton) {
    themeToggleButton.setAttribute("aria-label", nextTheme === "dark" ? "Switch to light mode" : "Switch to dark mode");
  }
  if (options.persist !== false) persistTheme(nextTheme);
}

function initTheme() {
  const urlTheme = urlDefaults.get("theme");
  const requestedTheme = urlTheme === "light" || urlTheme === "dark" ? urlTheme : storedTheme();
  applyTheme(requestedTheme || "dark", { persist: false });
}

function isAbortError(err) {
  return String(err?.stack || err?.message || err || "").includes("ABORTED_BY_CLIENT");
}

function loadClassicScript(src) {
  return new Promise((resolve, reject) => {
    const existing = Array.from(document.scripts).find((script) => script.dataset.flux2Src === src);
    if (existing?.dataset.loaded === "true") {
      resolve();
      return;
    }
    if (existing) existing.remove();
    const script = document.createElement("script");
    script.src = src;
    script.dataset.flux2Src = src;
    script.async = false;
    script.onload = () => {
      script.dataset.loaded = "true";
      resolve();
    };
    script.onerror = () => reject(new Error(`Failed to load ${src}`));
    if (!existing) document.body.appendChild(script);
  });
}

async function loadCustomRuntimeScripts() {
  if (!customRuntimeScriptsPromise) {
    customRuntimeScriptsPromise = (async () => {
      setLoadPhase("Loading custom WebGPU kernels");
      const version = encodeURIComponent(appAssetVersion());
      await loadClassicScript(`tools/custom_lowbit_webgpu/custom_lowbit_linear.js?v=${version}`);
      await loadClassicScript(`tools/custom_lowbit_webgpu/custom_transformer_runtime.js?v=${version}`);
    })();
  }
  return customRuntimeScriptsPromise;
}

async function loadEngineModule() {
  if (!engineModulePromise) {
    setLoadPhase("Loading browser engine");
    engineModulePromise = import(`./flux2-engine.js?v=${encodeURIComponent(appAssetVersion())}`);
  }
  return engineModulePromise;
}

function resetRuntimeLoadPromises() {
  engineReadyPromise = null;
  tokenizerPromise = null;
  if (!window.flux2Engine) engineModulePromise = null;
  if (typeof globalThis.createCustomFluxTransformerRuntime !== "function") customRuntimeScriptsPromise = null;
  transformersModulePromise = null;
}

function waitForEngine() {
  return new Promise((resolve, reject) => {
    const deadline = performance.now() + 30000;
    const tick = () => {
      if (window.flux2Engine && typeof window.flux2Engine.init === "function") {
        resolve(window.flux2Engine);
        return;
      }
      if (performance.now() > deadline) {
        reject(new Error("FLUX.2 browser engine did not load"));
        return;
      }
      setTimeout(tick, 50);
    };
    tick();
  });
}

async function sha256Hex(value) {
  const bytes = new TextEncoder().encode(value);
  const digest = await crypto.subtle.digest("SHA-256", bytes);
  return Array.from(new Uint8Array(digest), (byte) => byte.toString(16).padStart(2, "0")).join("");
}

function buildPromptText(prompt) {
  return `<|im_start|>user\n${prompt}<|im_end|>\n<|im_start|>assistant\n<think>\n\n</think>\n\n`;
}

function staticTextContextUrlForPrompt(prompt) {
  if (urlFlag("noStaticPromptContext")) return "";
  if (String(prompt || "") !== DEFAULT_PROMPT) return "";
  return resolveAssetUrl(configuredRuntimeBaseUrl(), "precomputed/default-prompt-context-f16.bin");
}

function staticTextProjectionUrlForPrompt(prompt, textTokens = 64) {
  if (urlFlag("noStaticPromptProjection")) return "";
  if (String(prompt || "") !== DEFAULT_PROMPT) return "";
  const filename = {
    32: "default-prompt-txtproj-32-f32.bin",
    64: "default-prompt-txtproj-64-f32.bin",
  }[Number(textTokens)];
  return filename ? resolveAssetUrl(configuredRuntimeBaseUrl(), `precomputed/${filename}`) : "";
}

function flattenTokenValues(value) {
  if (value == null) return [];
  if (Array.isArray(value)) {
    return value.flat(Infinity).map(Number);
  }
  if (ArrayBuffer.isView(value)) {
    return Array.from(value, Number);
  }
  if (value.data) {
    return flattenTokenValues(value.data);
  }
  if (value.tolist && typeof value.tolist === "function") {
    return flattenTokenValues(value.tolist());
  }
  return Array.from(value, Number);
}

function toInt64Padded(values, seqLen, padValue) {
  const out = new BigInt64Array(seqLen);
  const count = Math.min(values.length, seqLen);
  for (let i = 0; i < count; i++) out[i] = BigInt(Math.trunc(Number(values[i])));
  for (let i = count; i < seqLen; i++) out[i] = BigInt(padValue);
  return out;
}

function maskFromLength(length, seqLen) {
  const out = new BigInt64Array(seqLen);
  const count = Math.min(length, seqLen);
  for (let i = 0; i < count; i++) out[i] = 1n;
  return out;
}

async function loadTokenizer() {
  if (tokenizerPromise) return tokenizerPromise;
  setLoadPhase("Loading tokenizer");
  const { AutoTokenizer, env } = await loadTransformersModule();
  const modelBaseUrl = configuredModelBaseUrl();
  const tokenizerSpec = tokenizerLoadSpec(modelBaseUrl);
  env.allowLocalModels = !tokenizerSpec.remote;
  env.allowRemoteModels = tokenizerSpec.remote;
  env.localModelPath = "/";
  tokenizerPromise = AutoTokenizer.from_pretrained(tokenizerSpec.source, {
    ...tokenizerSpec.options,
    progress_callback: (progress) => {
      const file = progress?.file ? compactLoadUrlLabel(progress.file) : "tokenizer";
      const status = progress?.status ? ` ${progress.status}` : "";
      setLoadPhase(`Loading ${file}${status}`);
    },
  });
  return tokenizerPromise;
}

async function loadTransformersModule() {
  if (!transformersModulePromise) {
    setLoadPhase("Loading tokenizer runtime");
    transformersModulePromise = import("https://cdn.jsdelivr.net/npm/@huggingface/transformers@3.8.1");
  }
  return transformersModulePromise;
}

async function tokenizePrompt(prompt, seqLen) {
  const cachePayload = JSON.stringify({ model: "flux.2-klein-4b", text_seq_len: seqLen, prompt });
  const promptCacheKey = await sha256Hex(cachePayload);
  const cacheKey = `${seqLen}|${promptCacheKey}`;
  if (!urlFlag("noTokenizerCache") && tokenizedPromptCache.has(cacheKey)) {
    const cached = tokenizedPromptCache.get(cacheKey);
    tokenizedPromptCache.delete(cacheKey);
    tokenizedPromptCache.set(cacheKey, cached);
    return cached;
  }
  const tokenizer = await loadTokenizer();
  const text = buildPromptText(prompt);
  const encoded = await tokenizer(text, {
    truncation: true,
    max_length: seqLen,
    add_special_tokens: false,
  });
  const ids = flattenTokenValues(encoded.input_ids);
  const mask = encoded.attention_mask ? flattenTokenValues(encoded.attention_mask) : new Array(ids.length).fill(1);
  const padTokenId = Number(tokenizer.pad_token_id ?? 151643);
  const tokenized = {
    inputIds: toInt64Padded(ids, seqLen, padTokenId),
    attentionMask: mask.length ? toInt64Padded(mask.slice(0, ids.length), seqLen, 0) : maskFromLength(ids.length, seqLen),
    tokenCount: Math.min(ids.length, seqLen),
    promptCacheKey,
  };
  if (!urlFlag("noTokenizerCache")) {
    tokenizedPromptCache.set(cacheKey, tokenized);
    const maxEntries = Math.max(1, Math.trunc(Number(urlDefaults.get("tokenizerCacheEntries") || 8)));
    while (tokenizedPromptCache.size > maxEntries) {
      tokenizedPromptCache.delete(tokenizedPromptCache.keys().next().value);
    }
  }
  return tokenized;
}

async function initEngine() {
  if (engineReadyPromise) return engineReadyPromise;
  engineReadyPromise = (async () => {
    await Promise.all([loadCustomRuntimeScripts(), loadEngineModule()]);
    const engine = await waitForEngine();
    const modelBaseUrl = configuredModelBaseUrl();
    const runtimeBaseUrl = configuredRuntimeBaseUrl(modelBaseUrl);
    setLoadPhase("Loading model config and runtime manifest");
    console.log("[flux2] modelBaseUrl", modelBaseUrl);
    const result = await engine.init(modelBaseUrl, {
      executionProvider: "webgpu",
      customKernelBaseUrl: configuredCustomKernelBaseUrl(modelBaseUrl, runtimeBaseUrl),
      customTransformerMode: "custom-lowbit-webgpu",
      enableGraphCapture: urlFlag("graphCapture"),
      graphCaptureStages: urlDefaults.get("graphCaptureStages") ?? urlDefaults.get("captureStages") ?? "",
      profileWebGpu: urlFlag("profileWebGpu"),
      profileTopK: Number(urlDefaults.get("profileTopK") || 12),
      enableFusedTransformer: false,
      textContextCacheSize: 4,
      vaeEncoderCacheSize: Number(urlDefaults.get("vaeEncoderCacheEntries") || 3),
      persistentTextContextCache: !urlFlag("noPromptCache"),
      persistentTextContextCacheSize: Number(urlDefaults.get("promptCacheEntries") || 8),
      persistentVaeEncoderCache: !urlFlag("noVaeEncoderPersistentCache"),
      persistentVaeEncoderCacheSize: Number(urlDefaults.get("vaeEncoderPersistentCacheEntries") || 8),
      checkLegacyCustomBundles: urlFlag("legacyStatus"),
    });
    return { engine, init: result };
  })();
  return engineReadyPromise;
}

function img2ImgStrengthCurveExponent(curve) {
  if (curve === "linear") return 1;
  if (curve === "balanced") return 1.25;
  if (curve === "strong") return 3;
  if (curve === "rewrite") return 6;
  if (curve === "edit") return 2.5;
  return 2.5;
}

function effectiveImg2ImgStrength(strength, curve = strengthCurveEl?.value) {
  const clamped = Math.max(0, Math.min(1, Number(strength ?? 0.65)));
  return 1 - Math.pow(1 - clamped, img2ImgStrengthCurveExponent(curve));
}

function formatStrengthValue(value) {
  if (value >= 0.995 && value < 1) return value.toFixed(4);
  if (value >= 0.95 && value < 1) return value.toFixed(3);
  return value.toFixed(2);
}

function updateStrengthDisplay() {
  const strength = Number(strengthEl.value);
  strengthValueEl.textContent = `${strength.toFixed(2)} -> ${formatStrengthValue(effectiveImg2ImgStrength(strength))}`;
}

function setInitImageUi(file = null) {
  const hasFile = Boolean(file);
  if (initImageLabelEl) initImageLabelEl.textContent = hasFile ? file.name : "Choose optional image";
  if (clearInitImageButton) clearInitImageButton.hidden = !hasFile;
  if (img2imgControlsEl) img2imgControlsEl.hidden = !hasFile;
  if (!hasFile) {
    if (sourcePreviewWrap) sourcePreviewWrap.hidden = true;
    if (sourcePreviewEl) sourcePreviewEl.removeAttribute("src");
    if (sourceMetaEl) sourceMetaEl.textContent = "";
  }
}

function clearInitImage({ schedule = true } = {}) {
  if (currentSourceUrl) URL.revokeObjectURL(currentSourceUrl);
  currentSourceUrl = null;
  if (initImageInput) initImageInput.value = "";
  setInitImageUi(null);
  if (schedule) scheduleAutoWarmForCurrentSettings(0);
}

function setSelectValue(id, value) {
  if (!value) return;
  const element = $(id);
  if (!element) return;
  const stringValue = String(value);
  if (!element.options) {
    element.value = stringValue;
  } else if ([...element.options].some((option) => option.value === stringValue)) {
    element.value = stringValue;
  } else if ((id === "render-max" || id === "decode-max") && Number.isFinite(Number(stringValue)) && Number(stringValue) > 0) {
    const option = document.createElement("option");
    option.value = stringValue;
    option.textContent = stringValue;
    element.appendChild(option);
    element.value = stringValue;
  }
}

function setInputValue(id, value) {
  if (value === null || value === undefined || value === "") return;
  const element = $(id);
  if (!element) return;
  element.value = String(value);
}

function setResolutionAdvancedVisible(visible) {
  if (!resolutionAdvancedEl) return;
  resolutionAdvancedEl.hidden = !visible;
}

function clampResolutionValue(value, fallback = 256) {
  const number = Math.max(16, Math.trunc(Number(value) || fallback));
  return Math.max(16, Math.round(number / 16) * 16);
}

function nearestMultipleOf16(value) {
  return clampResolutionValue(value);
}

function dimensionsAreCommonSquare() {
  const width = Number($("width").value);
  const height = Number($("height").value);
  return width === height && COMMON_RESOLUTIONS.includes(width);
}

function setAspectLock(enabled) {
  aspectLockEnabled = Boolean(enabled);
  if (aspectLockButton) {
    aspectLockButton.setAttribute("aria-pressed", aspectLockEnabled ? "true" : "false");
    aspectLockButton.setAttribute("aria-label", aspectLockEnabled ? "Unlock aspect ratio" : "Lock aspect ratio");
  }
  if (aspectLockIconEl) aspectLockIconEl.textContent = aspectLockEnabled ? "link" : "link_off";
  if (aspectRatioEl && aspectRatioEl.value === "free" && aspectLockEnabled) {
    aspectRatioEl.value = "custom";
  }
}

function currentAspectRatio() {
  const width = Number($("width").value) || 1;
  const height = Number($("height").value) || 1;
  return width / height;
}

function rememberCurrentAspectRatio() {
  const ratio = currentAspectRatio();
  if (Number.isFinite(ratio) && ratio > 0) aspectLockRatio = ratio;
}

function syncAspectSelectFromDimensions() {
  if (!aspectRatioEl || aspectSyncing) return;
  if (!aspectLockEnabled) {
    aspectRatioEl.value = "free";
    return;
  }
  const ratio = currentAspectRatio();
  const matched = Object.entries(ASPECT_RATIOS).find(([, value]) => Math.abs(ratio - value) < 0.015);
  aspectRatioEl.value = matched ? matched[0] : "custom";
}

function applyAspectToHeight() {
  if (!aspectLockEnabled || !aspectLockRatio) return;
  const width = clampResolutionValue($("width").value);
  const nextHeight = nearestMultipleOf16(width / aspectLockRatio);
  aspectSyncing = true;
  $("width").value = String(width);
  $("height").value = String(nextHeight);
  aspectSyncing = false;
}

function applyAspectToWidth() {
  if (!aspectLockEnabled || !aspectLockRatio) return;
  const height = clampResolutionValue($("height").value);
  const nextWidth = nearestMultipleOf16(height * aspectLockRatio);
  aspectSyncing = true;
  $("height").value = String(height);
  $("width").value = String(nextWidth);
  aspectSyncing = false;
}

function syncResolutionPresetFromDimensions(options = {}) {
  if (!resolutionPresetEl) return;
  const width = clampResolutionValue($("width").value);
  const height = clampResolutionValue($("height").value);
  $("width").value = String(width);
  $("height").value = String(height);
  const commonSquare = dimensionsAreCommonSquare();
  if (options.preserveCustom && resolutionPresetEl.value === "custom") {
    setResolutionAdvancedVisible(true);
    rememberCurrentAspectRatio();
    syncAspectSelectFromDimensions();
    return;
  }
  resolutionPresetEl.value = commonSquare ? String(width) : "custom";
  if (commonSquare) {
    setResolutionAdvancedVisible(false);
    if (aspectRatioEl) aspectRatioEl.value = "1:1";
    aspectLockRatio = 1;
    return;
  }
  if (!commonSquare && options.showAdvancedForCustom) {
    setResolutionAdvancedVisible(true);
  }
  rememberCurrentAspectRatio();
  syncAspectSelectFromDimensions();
}

function applyResolutionPreset(value) {
  if (value === "custom") {
    setResolutionAdvancedVisible(true);
    rememberCurrentAspectRatio();
    syncAspectSelectFromDimensions();
    return;
  }
  const size = Number(value);
  if (!COMMON_RESOLUTIONS.includes(size)) return;
  $("width").value = String(size);
  $("height").value = String(size);
  aspectLockRatio = 1;
  setAspectLock(true);
  if (aspectRatioEl) aspectRatioEl.value = "1:1";
  setResolutionAdvancedVisible(false);
}

function applyUrlDefaults() {
  const params = urlDefaults;
  const resolution = params.get("resolution") ?? params.get("size");
  const resolutionSize = Number(resolution);
  if (COMMON_RESOLUTIONS.includes(resolutionSize)) {
    setInputValue("width", resolutionSize);
    setInputValue("height", resolutionSize);
  }
  setInputValue("prompt", params.get("prompt"));
  setInputValue("width", params.get("w") ?? params.get("width"));
  setInputValue("height", params.get("h") ?? params.get("height"));
  setInputValue("steps", params.get("steps"));
  setInputValue("seed", params.get("seed"));
  setInputValue("strength", params.get("strength"));
  setSelectValue("backend", params.get("backend"));
  setSelectValue("speed-profile", params.get("profile") ?? params.get("speed"));
  setSelectValue("strength-curve", params.get("curve") ?? params.get("strengthCurve"));
  setSelectValue("fit-mode", params.get("fit"));
  syncResolutionPresetFromDimensions({ showAdvancedForCustom: true });
}

function urlFlag(name) {
  const value = urlDefaults.get(name);
  return value === "1" || value === "true" || value === "yes" || value === "on";
}

function selectedSpeedConfig(width, height, requestedProfileOverride = "") {
  const requestedProfile = requestedProfileOverride || $("speed-profile").value;
  const imageTokens = Math.ceil(width / 16) * Math.ceil(height / 16);
  const maxDimension = Math.max(width, height);
  const subsecondFinal = requestedProfile === "subsecond-final";
  const subsecondUltra = requestedProfile === "subsecond-ultra";
  const subsecondInstant = requestedProfile === "subsecond-instant";
  const numericUrlDefault = (name, fallback) => {
    const value = Number(urlDefaults.get(name) || 0);
    return Number.isFinite(value) && value > 0 ? value : fallback;
  };
  const approximateCache = requestedProfile === "turbo-cache" ||
    requestedProfile === "ab-cache" ||
    requestedProfile === "tail-cache" ||
    requestedProfile === "tail-cache-lite" ||
    requestedProfile === "tail-cache-mid" ||
    requestedProfile === "tail-cache-fast" ||
    subsecondFinal ||
    subsecondUltra ||
    subsecondInstant ||
    requestedProfile === "subsecond-cache" ||
    requestedProfile === "subsecond-preview";
  const tailCacheProfile = requestedProfile === "tail-cache" ||
    requestedProfile === "tail-cache-lite" ||
    requestedProfile === "tail-cache-mid" ||
    requestedProfile === "tail-cache-fast";
  const approxReusePredEvery = requestedProfile === "subsecond-cache" ||
    subsecondInstant ||
    requestedProfile === "subsecond-preview"
    ? 4
    : (requestedProfile === "turbo-cache" || requestedProfile === "ab-cache" ? 2 : 0);
  const approxPredictionMode = urlDefaults.get("approxMode") ||
    urlDefaults.get("approxPredictionMode") ||
    (requestedProfile === "ab-cache" ? "ab2" : "raw");
  const requestedImg2ImgStepPolicy = urlDefaults.get("img2imgStepPolicy") || urlDefaults.get("img2imgSteps") || "";
  const fastImg2ImgProfile = subsecondFinal ||
    subsecondUltra ||
    subsecondInstant ||
    requestedProfile === "subsecond-preview" ||
    requestedProfile === "subsecond-cache" ||
    tailCacheProfile;
  const img2imgStepPolicy = requestedImg2ImgStepPolicy === "full" || requestedImg2ImgStepPolicy === "adaptive"
    ? requestedImg2ImgStepPolicy
    : (fastImg2ImgProfile ? "adaptive" : "full");
  let autoPreviewRenderMaxSize = 0;
  if (subsecondInstant && maxDimension > 256) {
    autoPreviewRenderMaxSize = maxDimension <= 512 ? 192 : 160;
  } else if (subsecondUltra && maxDimension > 256) {
    autoPreviewRenderMaxSize = maxDimension <= 512 ? 224 : 192;
  } else if (requestedProfile === "subsecond-preview" && maxDimension > 256) {
    autoPreviewRenderMaxSize = 256;
  } else if (requestedProfile === "tail-cache" && maxDimension > 512) {
    autoPreviewRenderMaxSize = 512;
  } else if ((requestedProfile === "tail-cache-lite" || (subsecondFinal && maxDimension <= 512)) && maxDimension > 272) {
    autoPreviewRenderMaxSize = 272;
  } else if (requestedProfile === "tail-cache-mid" && maxDimension > 384) {
    autoPreviewRenderMaxSize = 384;
  } else if (requestedProfile === "tail-cache-fast" && maxDimension > 320) {
    autoPreviewRenderMaxSize = 320;
  } else if (subsecondFinal && maxDimension > 512 && maxDimension > 240) {
    autoPreviewRenderMaxSize = 240;
  }
  const autoPreviewDecodeMaxSize = (
    requestedProfile === "subsecond-preview" ||
    requestedProfile === "tail-cache" ||
    requestedProfile === "tail-cache-lite" ||
    requestedProfile === "tail-cache-mid" ||
    requestedProfile === "tail-cache-fast" ||
    subsecondFinal ||
    subsecondUltra ||
    subsecondInstant
  ) && maxDimension > 256 ? 256 : 0;
  const forcedKernelProfile = urlDefaults.get("kernelProfile") || urlDefaults.get("kernel");
  const defaultLinearTileCols = maxDimension <= 256
    ? 128
    : (maxDimension <= 1024 ? 64 : undefined);
  const customTextTokenLimit = urlFlag("noTextTrim")
    ? 0
    : (Number(urlDefaults.get("textTokens") || 0) || (subsecondInstant ? 64 : (requestedProfile === "subsecond-preview" ? 128 : 512)));
  const customMinTextTokens = Number(urlDefaults.get("minTextTokens") || 0) ||
    (requestedProfile === "subsecond-preview" ? 64 : 32);
  const profile = forcedKernelProfile ||
    (requestedProfile === "auto" || requestedProfile === "progressive" || requestedProfile === "progressive-fast"
    ? "all-dp4a"
    : approximateCache
      ? "all-dp4a"
      : requestedProfile);
  return {
    profile,
    requestedProfile,
    customSingleLinear1Output: "f16",
    customSingleLinear1QkvBackend: profile === "all-dp4a" ? "dp4a" : "q4",
    customSingleLinear1MlpBackend: profile === "all-dp4a" || profile === "mlp-dp4a" ? "dp4a" : "q4",
    customSingleLinear1Q4ActivationScale: "row",
    customSingleLinear2Backend: "dp4a",
    customLinearTileCols: numericUrlDefault("linearTileCols", defaultLinearTileCols),
    customProjTileCols: numericUrlDefault("projTileCols", undefined),
    customFinalTileCols: numericUrlDefault("finalTileCols", undefined),
    customWChunkCols: numericUrlDefault("wChunkCols", undefined),
    customLinearRowBlock: numericUrlDefault("linearRowBlock", numericUrlDefault("linearRows", undefined)),
    customSingleQ4TileCols: numericUrlDefault("singleQ4TileCols", undefined),
    customSingleQ4KChunk: numericUrlDefault("singleQ4KChunk", undefined),
    customSingleQ4Dp4aTileCols: numericUrlDefault("singleQ4Dp4aTileCols", undefined),
    customAttentionTileKeys: numericUrlDefault("attentionTileKeys", 8),
    customAttentionQueryRows: numericUrlDefault("attentionQueryRows", 16),
    customSingleAttentionKernel: urlDefaults.get("singleAttentionKernel") || urlDefaults.get("attentionKernel") || "",
    customSingleQkNormStorage: urlDefaults.get("qkNormStorage") || urlDefaults.get("singleQkNormStorage") || "",
    customApproxReusePredEvery: approxReusePredEvery,
    customApproxPredictionMode: approxPredictionMode,
    customApproxAbScale: Number(urlDefaults.get("approxAbScale") || 0) || undefined,
    customSkipSingleBlocksFromStep: Number(urlDefaults.get("skipSingleBlocksFromStep") || urlDefaults.get("cacheSingleBlocksFromStep") || 0),
    customSkipSingleBlocksFromBlock: Number(urlDefaults.get("skipSingleBlocksFromBlock") || urlDefaults.get("cacheSingleBlocksFromBlock") || 0),
    customReuseSingleTailFromStep: Number(urlDefaults.get("reuseSingleTailFromStep") || urlDefaults.get("cacheSingleTailFromStep") || 0) ||
      ((tailCacheProfile || ((subsecondFinal || subsecondUltra) && maxDimension > 256)) ? 2 : 0),
    customReuseSingleTailFromBlock: Number(urlDefaults.get("reuseSingleTailFromBlock") || urlDefaults.get("cacheSingleTailFromBlock") || 0) ||
      (subsecondUltra && maxDimension > 256 ? 4 : (subsecondFinal && maxDimension > 256 ? 8 : (tailCacheProfile ? 12 : 0))),
    customProfilePhases: urlFlag("profilePhases") || urlFlag("phaseProfile"),
    customProfileSingleParts: urlFlag("profileSingleParts") || urlFlag("singlePartProfile"),
    customStepSubmitFusion: urlFlag("stepFusion") || urlFlag("stepSubmitFusion"),
    customSingleComputePass: urlFlag("singlePass"),
    customMaxDoubleBlocks: Number(urlDefaults.get("doubleBlocks") || 0) || (subsecondInstant ? 3 : 0),
    customMaxSingleBlocks: Number(urlDefaults.get("singleBlocks") || 0) || (subsecondInstant ? 8 : 0),
    autoPreviewRenderMaxSize,
    autoPreviewDecodeMaxSize,
    customTextTokenLimit,
    customMinTextTokens,
    img2imgStepPolicy,
  };
}

function requestWithSpeedProfile(request, profile, options = {}) {
  const speed = selectedSpeedConfig(request.width, request.height, profile);
  const useSelectedCaps = options.useSelectedCaps !== false;
  const selectedPreviewRenderMaxSize = useSelectedCaps ? Number($("render-max").value) || 0 : 0;
  const selectedPreviewDecodeMaxSize = useSelectedCaps ? Number($("decode-max").value) || 0 : 0;
  return {
    ...request,
    speed,
    previewRenderMaxSize: selectedPreviewRenderMaxSize || speed.autoPreviewRenderMaxSize || 0,
    previewDecodeMaxSize: selectedPreviewDecodeMaxSize || speed.autoPreviewDecodeMaxSize || 0,
  };
}

function currentInitImageKey(width = "", height = "", fitMode = "") {
  const file = initImageInput.files?.[0];
  if (!file) return "";
  return [file.name, file.size, file.lastModified || 0, `${width}x${height}`, fitMode].join("|");
}

function speedProfileLabel(speed) {
  if (speed.requestedProfile === "auto") return `auto -> ${speed.profile}`;
  if (speed.requestedProfile === "progressive") return "progressive";
  if (speed.requestedProfile === "progressive-fast") return "fast-default exact";
  if (speed.requestedProfile && speed.profile && speed.requestedProfile !== speed.profile) {
    return `${speed.requestedProfile} -> ${speed.profile}`;
  }
  return speed.profile;
}

function progressivePreviewProfileForRequest(request) {
  const override = urlDefaults.get("progressivePreview") || urlDefaults.get("previewProfile");
  if (override) return override;
  return "subsecond-instant";
}

function progressiveFinalProfileForRequest(request) {
  const override = urlDefaults.get("progressiveFinal") || urlDefaults.get("finalProfile");
  if (override) return override;
  if (request.speed.requestedProfile === "progressive-fast") return "subsecond-ultra";
  const maxDimension = Math.max(request.width, request.height);
  if (maxDimension > 512) return "tail-cache-mid";
  if (maxDimension === 512) return "tail-cache-lite";
  return "auto";
}

function speedCacheSignature(speed = {}) {
  return {
    requestedProfile: speed.requestedProfile,
    profile: speed.profile,
    reuse: speed.customApproxReusePredEvery,
    approxMode: speed.customApproxPredictionMode,
    approxAbScale: speed.customApproxAbScale,
    textLimit: speed.customTextTokenLimit,
    minText: speed.customMinTextTokens,
    qkv: speed.customSingleLinear1QkvBackend,
    mlp: speed.customSingleLinear1MlpBackend,
    linear2: speed.customSingleLinear2Backend,
    linearTileCols: speed.customLinearTileCols,
    projTileCols: speed.customProjTileCols,
    finalTileCols: speed.customFinalTileCols,
    wChunkCols: speed.customWChunkCols,
    linearRowBlock: speed.customLinearRowBlock,
    singleAttentionKernel: speed.customSingleAttentionKernel,
    qkNormStorage: speed.customSingleQkNormStorage,
    skipSingleBlocksFromStep: speed.customSkipSingleBlocksFromStep,
    skipSingleBlocksFromBlock: speed.customSkipSingleBlocksFromBlock,
    reuseSingleTailFromStep: speed.customReuseSingleTailFromStep,
    reuseSingleTailFromBlock: speed.customReuseSingleTailFromBlock,
    profilePhases: speed.customProfilePhases,
    profileSingleParts: speed.customProfileSingleParts,
    stepSubmitFusion: speed.customStepSubmitFusion,
    singlePass: speed.customSingleComputePass,
    doubleBlocks: speed.customMaxDoubleBlocks,
    singleBlocks: speed.customMaxSingleBlocks,
    img2imgStepPolicy: speed.img2imgStepPolicy,
  };
}

function warmPlanForRequest(request) {
  const warmProfile = (
    request.speed.requestedProfile === "progressive"
  ) && Math.max(request.width, request.height) > 256
    ? progressivePreviewProfileForRequest(request)
    : "";
  return {
    warmProfile,
    warmRequest: warmProfile
      ? requestWithSpeedProfile(request, warmProfile, { useSelectedCaps: false })
      : request,
  };
}

function backgroundPrepareRequestForRequest(request) {
  if (
    !request.hasInitImage &&
    request.speed.requestedProfile === "progressive" &&
    Math.max(request.width, request.height) > 256
  ) {
    return requestWithSpeedProfile(request, progressivePreviewProfileForRequest(request), { useSelectedCaps: false });
  }
  return request;
}

function progressiveFinalPrepareRequestForRequest(request) {
  if (
    !request.hasInitImage &&
    request.speed.requestedProfile === "progressive" &&
    Math.max(request.width, request.height) > 256
  ) {
    return requestWithSpeedProfile(request, progressiveFinalProfileForRequest(request), { useSelectedCaps: true });
  }
  return null;
}

function warmKeyForRequest(request) {
  const { warmRequest } = warmPlanForRequest(request);
  return JSON.stringify({
    prompt: warmRequest.prompt,
    width: warmRequest.width,
    height: warmRequest.height,
    steps: warmRequest.numSteps,
    backend: warmRequest.transformerBackend,
    hasInitImage: warmRequest.hasInitImage,
    initImageKey: warmRequest.hasInitImage ? warmRequest.initImageKey : undefined,
    strength: warmRequest.hasInitImage ? warmRequest.strength : undefined,
    strengthCurve: warmRequest.hasInitImage ? warmRequest.strengthCurve : undefined,
    effectiveStrength: warmRequest.hasInitImage
      ? Number(effectiveImg2ImgStrength(warmRequest.strength, warmRequest.strengthCurve).toFixed(6))
      : undefined,
    fitMode: warmRequest.hasInitImage ? warmRequest.fitMode : undefined,
    previewRenderMaxSize: warmRequest.previewRenderMaxSize,
    previewDecodeMaxSize: warmRequest.previewDecodeMaxSize,
    speed: speedCacheSignature(warmRequest.speed),
  });
}

function warmResultKeyForRequest(request) {
  const { warmRequest } = warmPlanForRequest(request);
  const requestedSeed = Number(warmRequest.requestedSeed);
  const fixedSeed = Number.isFinite(requestedSeed) && requestedSeed >= 0
    ? Math.trunc(requestedSeed)
    : "random";
  return JSON.stringify({
    warmKey: warmKeyForRequest(request),
    seed: fixedSeed,
  });
}

function assetPrepareKeyForRequest(request) {
  return JSON.stringify({
    backend: request.transformerBackend,
    doubleBlocks: request.speed.customMaxDoubleBlocks || 5,
    singleBlocks: request.speed.customMaxSingleBlocks || 20,
  });
}

function shouldAssetPrepareRequest(request) {
  if (urlFlag("noAutowarm") || urlFlag("noAssetWarm")) return false;
  return request.transformerBackend === "custom-lowbit-webgpu";
}

function fullManifestLinearById(manifest, id) {
  const linears = Array.isArray(manifest?.linears) ? manifest.linears : [];
  return linears.find((item) => item.id === id || item.name === id || item.source_node === id) || null;
}

function fullManifestQkNormById(manifest, id) {
  const qkNorms = Array.isArray(manifest?.constants?.qk_norms) ? manifest.constants.qk_norms : [];
  return qkNorms.find((item) => item.id === id || item.name === id) || null;
}

function estimateLinearAssetBytes(linear) {
  if (!linear) return { bytes: 0, files: 0 };
  if (linear.i8_dp4a) {
    const packed = Number(linear.i8_dp4a.packed_u32_count || 0) * 4;
    const scales = Number(linear.i8_dp4a.scale_count || 0) * 4;
    return { bytes: packed + scales, files: 2 };
  }
  if (linear.q4) {
    const qweight = Number(linear.q4.qweight_u32_count || linear.q4.packed_u32_count || 0) * 4;
    const scales = Number(linear.q4.scale_count || 0) * 2;
    const zeroPoints = Number(linear.q4.zero_point_count || linear.q4.zero_points_u32_count || 0) * 4;
    return { bytes: qweight + scales + zeroPoints, files: 3 };
  }
  return { bytes: 0, files: 0 };
}

function estimateQkNormBytes(entry) {
  if (!entry) return { bytes: 0, files: 0 };
  const count = Array.isArray(entry.shape) && Number.isFinite(Number(entry.shape[0])) ? Number(entry.shape[0]) : 128;
  return { bytes: count * 2 * 2, files: 2 };
}

function estimateCustomTransformerAssetSet(manifest, request) {
  const doubleBlockCount = Math.max(1, Math.min(5, Math.trunc(Number(request.speed.customMaxDoubleBlocks || 5))));
  const singleBlockCount = Math.max(0, Math.min(20, Math.trunc(Number(request.speed.customMaxSingleBlocks || 20))));
  const linearIds = ["img_in", "txt_in", "final_layer.linear"];
  const qkNormIds = [];
  for (let block = 0; block < doubleBlockCount; block += 1) {
    linearIds.push(
      `double_blocks.${block}.img_attn.qkv`,
      `double_blocks.${block}.txt_attn.qkv`,
      `double_blocks.${block}.img_attn.proj`,
      `double_blocks.${block}.txt_attn.proj`,
      `double_blocks.${block}.img_mlp.0`,
      `double_blocks.${block}.img_mlp.2`,
      `double_blocks.${block}.txt_mlp.0`,
      `double_blocks.${block}.txt_mlp.2`,
    );
    qkNormIds.push(`double_blocks.${block}.img_attn.norm`, `double_blocks.${block}.txt_attn.norm`);
  }
  for (let block = 0; block < singleBlockCount; block += 1) {
    linearIds.push(`single_blocks.${block}.linear1`, `single_blocks.${block}.linear2`);
    qkNormIds.push(`single_blocks.${block}.norm`);
  }
  let bytes = 0;
  let files = 0;
  for (const id of linearIds) {
    const estimate = estimateLinearAssetBytes(fullManifestLinearById(manifest, id));
    bytes += estimate.bytes;
    files += estimate.files;
  }
  for (const id of qkNormIds) {
    const estimate = estimateQkNormBytes(fullManifestQkNormById(manifest, id));
    bytes += estimate.bytes;
    files += estimate.files;
  }
  return { bytes, files, doubleBlockCount, singleBlockCount };
}

async function prepareCustomAssetLoadEstimate(request) {
  if (!loadProgressState.visible || !shouldAssetPrepareRequest(request)) return null;
  try {
    const modelBaseUrl = configuredModelBaseUrl();
    const runtimeBaseUrl = configuredRuntimeBaseUrl(modelBaseUrl);
    const customKernelBaseUrl = configuredCustomKernelBaseUrl(modelBaseUrl, runtimeBaseUrl);
    const manifestUrl = resolveAssetUrl(customKernelBaseUrl, "full_transformer/manifest.json");
    setLoadPhase("Reading transformer asset manifest");
    const response = await fetch(manifestUrl);
    if (!response.ok) throw new Error(`HTTP ${response.status}`);
    const manifest = await response.json();
    const estimate = estimateCustomTransformerAssetSet(manifest, request);
    if (estimate.bytes > 0) {
      setLoadEstimate(estimate.bytes, estimate.files);
      setLoadPhase(`Downloading transformer assets (${formatBytesCompact(estimate.bytes)})`);
    }
    return estimate;
  } catch (err) {
    console.warn("[flux2] custom asset byte estimate failed", err);
    return null;
  }
}

function textContextPrepareKeyForRequest(request) {
  return JSON.stringify({
    prompt: request.prompt,
    backend: request.transformerBackend,
    textLimit: request.speed.customTextTokenLimit,
    minText: request.speed.customMinTextTokens,
    projectionUrl: staticTextProjectionUrlForPrompt(request.prompt, request.speed.customMinTextTokens || 64),
  });
}

function shouldTextContextPrepareRequest(request) {
  if (urlFlag("noAutowarm") || urlFlag("noTextWarm")) return false;
  if (shouldBypassSourceOnly(request)) return false;
  return request.transformerBackend === "custom-lowbit-webgpu";
}

function startBackgroundTextContextPrepareForCurrentSettings(request = readRequest()) {
  if (!canRunRuntimeWork()) return false;
  const prepareRequest = backgroundPrepareRequestForRequest(request);
  if (!shouldTextContextPrepareRequest(prepareRequest)) return false;
  const key = textContextPrepareKeyForRequest(prepareRequest);
  if (backgroundTextContextPreparePromise && backgroundTextContextPrepareKey === key) return true;
  backgroundTextContextPrepareKey = key;
  backgroundTextContextPreparePromise = initEngine()
    .then(async ({ engine, init }) => {
      if (typeof engine.encodeText !== "function") return null;
      setLoadPhase("Preparing text context");
      const seqLen = Number(init.config.text_seq_len || 512);
      const tokenized = await tokenizePrompt(prepareRequest.prompt, seqLen);
      const params = buildGenerateParams(prepareRequest, tokenized, null);
      if (typeof engine.prepareCustomTransformerTextProjection === "function") {
        return await engine.prepareCustomTransformerTextProjection(params);
      }
      return await engine.encodeText(params);
    })
    .then((result) => {
      if (result?.shape || result?.textEncoder) {
        console.log("[flux2] text/projection prepared", result.shape, result.load || result.textEncoder || null);
      }
      return result;
    })
    .catch((err) => {
      console.warn("[flux2] text context prepare failed", err);
      return null;
    })
    .finally(() => {
      backgroundTextContextPreparePromise = null;
      backgroundTextContextPrepareKey = "";
    });
  return true;
}

function transformerSetupPrepareKeyForRequest(request) {
  return JSON.stringify({
    prompt: request.prompt,
    width: request.width,
    height: request.height,
    steps: request.numSteps,
    backend: request.transformerBackend,
    hasInitImage: request.hasInitImage,
    previewRenderMaxSize: request.previewRenderMaxSize,
    speed: speedCacheSignature(request.speed),
  });
}

function shouldTransformerSetupPrepareRequest(request) {
  if (urlFlag("noAutowarm") || urlFlag("noStageWarm")) return false;
  if (request.transformerBackend !== "custom-lowbit-webgpu") return false;
  if (shouldBypassSourceOnly(request)) return false;
  if (shouldAutoWarmRequest(request)) return false;
  return true;
}

function shouldTransformerDispatchWarmupRequest(request) {
  if (urlFlag("noDispatchWarm")) return false;
  if (urlFlag("dispatchWarm")) return true;
  if (request.hasInitImage) return false;
  const renderSize = plannedRenderSizeForRequest(request);
  const plannedMaxDimension = Math.max(renderSize.width, renderSize.height);
  return plannedMaxDimension <= 512;
}

function startBackgroundTransformerSetupPrepareForCurrentSettings(request = readRequest()) {
  if (!canRunRuntimeWork()) return false;
  const prepareRequest = backgroundPrepareRequestForRequest(request);
  if (!shouldTransformerSetupPrepareRequest(prepareRequest)) return false;
  const dispatchWarmup = shouldTransformerDispatchWarmupRequest(prepareRequest);
  const key = `${transformerSetupPrepareKeyForRequest(prepareRequest)}|dispatch=${dispatchWarmup ? 1 : 0}`;
  if (backgroundTransformerSetupPreparePromise && backgroundTransformerSetupPrepareKey === key) return true;
  backgroundTransformerSetupPrepareKey = key;
  backgroundTransformerSetupPreparePromise = initEngine()
    .then(async ({ engine, init }) => {
      if (typeof engine.prepareCustomTransformerStageSetup !== "function") return null;
      setLoadPhase(dispatchWarmup ? "Preparing transformer dispatch warmup" : "Preparing transformer setup");
      const seqLen = Number(init.config.text_seq_len || 512);
      const tokenized = await tokenizePrompt(prepareRequest.prompt, seqLen);
      const plannedTextTokens = plannedCustomTextTokens(prepareRequest, tokenized.attentionMask, seqLen);
      return await engine.prepareCustomTransformerStageSetup({
        width: prepareRequest.width,
        height: prepareRequest.height,
        hasInitImage: prepareRequest.hasInitImage,
        dispatchWarmup,
        previewRenderMaxSize: prepareRequest.previewRenderMaxSize,
        previewRenderInitImage: shouldPreviewRenderInitImage(prepareRequest),
        numSteps: prepareRequest.numSteps,
        textTokens: plannedTextTokens,
        textProjectionUrl: staticTextProjectionUrlForPrompt(prepareRequest.prompt, plannedTextTokens),
        ...prepareRequest.speed,
      });
    })
    .then((result) => {
      if (result?.load) {
        console.log(dispatchWarmup ? "[flux2] custom transformer dispatch warmed" : "[flux2] custom transformer stage prepared", result.load, result.shape);
      }
      return result;
    })
    .catch((err) => {
      console.warn("[flux2] custom transformer stage prepare failed", err);
      return null;
    })
    .finally(() => {
      backgroundTransformerSetupPreparePromise = null;
      backgroundTransformerSetupPrepareKey = "";
    });
  return true;
}

function defaultVaeChunkSizeForDecodeMax(plannedDecodeMax) {
  if (plannedDecodeMax >= 768) return 4096;
  if (plannedDecodeMax >= 512) return 2048;
  return 0;
}

function plannedDecodeMaxForRequest(request) {
  return request.previewDecodeMaxSize && Math.max(request.width, request.height) > request.previewDecodeMaxSize
    ? request.previewDecodeMaxSize
    : Math.max(request.width, request.height);
}

function shouldAutoWarmRequest(request) {
  if (urlFlag("autowarm")) return true;
  if (urlFlag("noAutowarm")) return false;
  if (request.hasInitImage) return false;
  if (urlFlag("hiddenWarm")) return true;
  const maxDimension = Math.max(request.width, request.height);
  if (
    request.transformerBackend === "custom-lowbit-webgpu" &&
    !request.speed.customApproxReusePredEvery &&
    maxDimension <= 256 &&
    (request.speed.requestedProfile === "auto" || request.speed.requestedProfile === "progressive")
  ) {
    return false;
  }
  if (
    request.speed.requestedProfile === "subsecond-preview" ||
    request.speed.requestedProfile === "subsecond-final" ||
    request.speed.requestedProfile === "progressive" ||
    request.speed.requestedProfile === "progressive-fast" ||
    request.speed.requestedProfile === "tail-cache" ||
    request.speed.requestedProfile === "tail-cache-lite" ||
    request.speed.requestedProfile === "tail-cache-mid" ||
    request.speed.requestedProfile === "tail-cache-fast"
  ) return false;
  return request.transformerBackend === "custom-lowbit-webgpu" &&
    request.speed.requestedProfile === "auto" &&
    !request.hasInitImage &&
    maxDimension <= 256;
}

function startBackgroundAssetPrepareForCurrentSettings(request = readRequest()) {
  if (!canRunRuntimeWork()) return false;
  if (!shouldAssetPrepareRequest(request)) return false;
  const key = assetPrepareKeyForRequest(request);
  if (backgroundAssetPreparePromise && backgroundAssetPrepareKey === key) return true;
  backgroundAssetPrepareKey = key;
  backgroundAssetPreparePromise = initEngine()
    .then(({ engine }) => {
      if (typeof engine.prepareCustomTransformerAssets !== "function") return null;
      setLoadPhase("Downloading transformer assets");
      return engine.prepareCustomTransformerAssets({
        maxDoubleBlocks: request.speed.customMaxDoubleBlocks || 5,
        maxSingleBlocks: request.speed.customMaxSingleBlocks || 20,
      });
    })
    .then((result) => {
      if (result?.summary) {
        console.log("[flux2] custom transformer assets prepared", result.summary);
      }
      return result;
    })
    .catch((err) => {
      console.warn("[flux2] custom transformer asset prepare failed", err);
      return null;
    })
    .finally(() => {
      backgroundAssetPreparePromise = null;
      backgroundAssetPrepareKey = "";
    });
  return true;
}

function vaePrepareKeyForRequest(request) {
  const plannedDecodeMax = plannedDecodeMaxForRequest(request);
  return JSON.stringify({
    width: request.width,
    height: request.height,
    hasInitImage: request.hasInitImage,
    previewRenderMaxSize: request.previewRenderMaxSize,
    previewDecodeMaxSize: request.previewDecodeMaxSize,
    vaeChunk: Number(urlDefaults.get("vaeChunk") || 0) || defaultVaeChunkSizeForDecodeMax(plannedDecodeMax),
    maxAutoVaeChunkSeq: Number(urlDefaults.get("maxAutoVaeChunkSeq") || 0),
  });
}

function vaeEncoderPrepareKeyForRequest(request) {
  const renderSize = plannedRenderSizeForRequest(request);
  return JSON.stringify({
    width: renderSize.width,
    height: renderSize.height,
    fitMode: request.fitMode,
    initImageKey: currentInitImageKey(renderSize.width, renderSize.height, request.fitMode),
    previewRenderInitImage: shouldPreviewRenderInitImage(request),
  });
}

function shouldVaeEncoderPrepareRequest(request) {
  if (urlFlag("noAutowarm") || urlFlag("noVaeEncoderWarm")) return false;
  if (!request.hasInitImage) return false;
  if (shouldBypassSourceOnly(request)) return false;
  return true;
}

function startBackgroundVaeEncoderPrepareForCurrentSettings(request = readRequest()) {
  if (!canRunRuntimeWork()) return false;
  if (!shouldVaeEncoderPrepareRequest(request)) return false;
  const key = vaeEncoderPrepareKeyForRequest(request);
  if (backgroundVaeEncoderPreparePromise && backgroundVaeEncoderPrepareKey === key) return true;
  backgroundVaeEncoderPrepareKey = key;
  backgroundVaeEncoderPreparePromise = initEngine()
    .then(async ({ engine }) => {
      if (typeof engine.prepareVaeEncoderLatent !== "function") return null;
      setLoadPhase("Preparing source image latent");
      const renderSize = plannedRenderSizeForRequest(request);
      const initImage = await prepareInitImage(renderSize.width, renderSize.height, request.fitMode);
      if (!initImage) return null;
      return await engine.prepareVaeEncoderLatent({
        width: renderSize.width,
        height: renderSize.height,
        initImage: initImage.data,
        initImageCacheKey: initImage.cacheKey || request.initImageKey,
        cacheVaeEncoder: !urlFlag("noVaeEncoderCache"),
      });
    })
    .then((result) => {
      if (result?.verdict) {
        console.log("[flux2] VAE encoder latent prepared", result);
      }
      return result;
    })
    .catch((err) => {
      console.warn("[flux2] VAE encoder latent prepare failed", err);
      return null;
    })
    .finally(() => {
      backgroundVaeEncoderPreparePromise = null;
      backgroundVaeEncoderPrepareKey = "";
    });
  return true;
}

function shouldVaePrepareRequest(request) {
  if (urlFlag("noAutowarm") || urlFlag("noVaeWarm")) return false;
  if (shouldAutoWarmRequest(request)) return false;
  return true;
}

function shouldVaeDispatchWarmupRequest(request) {
  if (urlFlag("noVaeDispatchWarm")) return false;
  if (urlFlag("vaeDispatchWarm") || urlFlag("dispatchWarm")) return true;
  if (request.hasInitImage) return false;
  return plannedDecodeMaxForRequest(request) <= 256;
}

async function waitForStartedPreparePromises() {
  const textPromise = backgroundTextContextPreparePromise;
  const transformerPromise = backgroundTransformerSetupPreparePromise;
  const vaeEncoderPromise = backgroundVaeEncoderPreparePromise;
  const vaePromise = backgroundVaePreparePromise;
  await Promise.all([textPromise, transformerPromise, vaeEncoderPromise, vaePromise].filter(Boolean).map(async (promise) => {
    try {
      await promise;
    } catch {
      // Generation can still build the normal path if eager preparation fails.
    }
  }));
}

function startStageAndVaePrepareForRequest(request) {
  if (!canRunRuntimeWork()) return false;
  const startedText = startBackgroundTextContextPrepareForCurrentSettings(request);
  const startedTransformer = startBackgroundTransformerSetupPrepareForCurrentSettings(request);
  if (request.hasInitImage && shouldVaeEncoderPrepareRequest(request)) {
    const startedVaeEncoder = startBackgroundVaeEncoderPrepareForCurrentSettings(request);
    return startedText || startedTransformer || startedVaeEncoder;
  }
  const startedVae = startBackgroundVaePrepareForCurrentSettings(request);
  return startedText || startedTransformer || startedVae;
}

function startBackgroundVaePrepareForCurrentSettings(request = readRequest()) {
  if (!canRunRuntimeWork()) return false;
  const prepareRequest = backgroundPrepareRequestForRequest(request);
  if (!shouldVaePrepareRequest(prepareRequest)) return false;
  const dispatchWarmup = shouldVaeDispatchWarmupRequest(prepareRequest);
  const key = `${vaePrepareKeyForRequest(prepareRequest)}|dispatch=${dispatchWarmup ? 1 : 0}`;
  if (backgroundVaePreparePromise && backgroundVaePrepareKey === key) return true;
  backgroundVaePrepareKey = key;
  const plannedDecodeMax = plannedDecodeMaxForRequest(prepareRequest);
  backgroundVaePreparePromise = initEngine()
    .then(({ engine }) => {
      if (typeof engine.prepareVaeSessions !== "function") return null;
      setLoadPhase(dispatchWarmup ? "Preparing VAE dispatch warmup" : "Preparing VAE sessions");
      return engine.prepareVaeSessions({
        width: prepareRequest.width,
        height: prepareRequest.height,
        hasInitImage: prepareRequest.hasInitImage,
        includeEncoder: prepareRequest.hasInitImage && !shouldVaeEncoderPrepareRequest(prepareRequest),
        dispatchWarmup,
        previewRenderMaxSize: prepareRequest.previewRenderMaxSize,
        previewRenderInitImage: shouldPreviewRenderInitImage(prepareRequest),
        previewDecodeMaxSize: prepareRequest.previewDecodeMaxSize,
        vaeAttentionChunkSize: Number(urlDefaults.get("vaeChunk") || 0) || defaultVaeChunkSizeForDecodeMax(plannedDecodeMax),
        maxAutoVaeAttentionChunkSeq: Number(urlDefaults.get("maxAutoVaeChunkSeq") || 0),
      });
    })
    .then((result) => {
      if (result?.decoder) {
        console.log(dispatchWarmup ? "[flux2] VAE dispatch warmed" : "[flux2] VAE sessions prepared", result);
      }
      return result;
    })
    .catch((err) => {
      console.warn("[flux2] VAE session prepare failed", err);
      return null;
    })
    .finally(() => {
      backgroundVaePreparePromise = null;
      backgroundVaePrepareKey = "";
    });
  return true;
}

function clearWarmSchedule() {
  if (warmScheduleTimer) {
    clearTimeout(warmScheduleTimer);
    warmScheduleTimer = 0;
  }
  if (backgroundDeepPrepareTimer) {
    clearTimeout(backgroundDeepPrepareTimer);
    backgroundDeepPrepareTimer = 0;
  }
  backgroundDeepPrepareToken += 1;
}

function cancelBackgroundWarm(message = "") {
  backgroundWarmResult = null;
  backgroundWarmResultKey = "";
  if (!backgroundWarmPromise) return false;
  backgroundWarmKey = "";
  window.flux2Engine?.abortGeneration?.();
  if (message && !foregroundBusy) setStatus(message);
  return true;
}

function startBackgroundWarmForCurrentSettings() {
  if (!canRunRuntimeWork()) return false;
  if (foregroundBusy) return false;
  const request = readRequest();
  if (!shouldAutoWarmRequest(request)) return false;
  const key = warmKeyForRequest(request);
  const resultKey = warmResultKeyForRequest(request);
  if (backgroundWarmResult?.key === key) {
    if (backgroundWarmResult.resultKey === resultKey) return true;
    backgroundWarmResult = null;
  }
  if (backgroundWarmPromise) {
    if (backgroundWarmKey === key && backgroundWarmResultKey === resultKey) return true;
    cancelBackgroundWarm();
  }
  backgroundWarmKey = key;
  backgroundWarmResultKey = resultKey;
  backgroundWarmResult = null;
  const warmPromise = warmCurrentSettings({ background: true }).then((warmResult) => {
    if (warmResult?.canReuseResult && backgroundWarmKey === warmResult.key && backgroundWarmResultKey === warmResult.resultKey) {
      backgroundWarmResult = warmResult;
    }
    return warmResult;
  }).catch((err) => {
    if (!foregroundBusy && !isAbortError(err)) setStatus(err?.stack || err?.message || String(err), true);
  }).finally(() => {
    if (backgroundWarmPromise !== warmPromise) return;
    backgroundWarmPromise = null;
    backgroundWarmKey = "";
    backgroundWarmResultKey = "";
    if (!foregroundBusy) {
      runButton.disabled = false;
      setButtonDisabled(warmButton, false);
      abortButton.disabled = true;
    }
  });
  backgroundWarmPromise = warmPromise;
  return true;
}

function scheduleBackgroundStageAndVaePrepareForCurrentSettings(request = readRequest(), delayMs = 750) {
  if (!canRunRuntimeWork()) return false;
  if (foregroundBusy || urlFlag("noAutowarm")) return false;
  if (backgroundDeepPrepareTimer) {
    clearTimeout(backgroundDeepPrepareTimer);
    backgroundDeepPrepareTimer = 0;
  }
  const token = ++backgroundDeepPrepareToken;
  const expectedWarmKey = warmKeyForRequest(request);
  const expectedAssetKey = assetPrepareKeyForRequest(request);
  backgroundDeepPrepareTimer = setTimeout(async () => {
    backgroundDeepPrepareTimer = 0;
    if (foregroundBusy || token !== backgroundDeepPrepareToken) return;
    const assetPromise = backgroundAssetPreparePromise;
    if (assetPromise && backgroundAssetPrepareKey === expectedAssetKey) {
      try {
        await assetPromise;
      } catch {
        // Stage preparation can still use the normal generation path if asset warm failed.
      }
    }
    if (foregroundBusy || token !== backgroundDeepPrepareToken) return;
    const currentRequest = readRequest();
    if (warmKeyForRequest(currentRequest) !== expectedWarmKey) return;
    startStageAndVaePrepareForRequest(currentRequest);
    await waitForStartedPreparePromises();
    if (foregroundBusy || token !== backgroundDeepPrepareToken) return;
    if (warmKeyForRequest(readRequest()) !== expectedWarmKey) return;
    startBackgroundVaePrepareForCurrentSettings(currentRequest);
    if (foregroundBusy || token !== backgroundDeepPrepareToken) return;
    if (warmKeyForRequest(readRequest()) !== expectedWarmKey) return;
    const finalPrepareRequest = progressiveFinalPrepareRequestForRequest(currentRequest);
    if (finalPrepareRequest) {
      startStageAndVaePrepareForRequest(finalPrepareRequest);
    }
  }, delayMs);
  return true;
}

function scheduleAutoWarmForCurrentSettings(delayMs = 350) {
  clearWarmSchedule();
  if (!canRunRuntimeWork()) return;
  if (foregroundBusy || urlFlag("noAutowarm")) return;
  const request = readRequest();
  startBackgroundAssetPrepareForCurrentSettings(request);
  scheduleBackgroundStageAndVaePrepareForCurrentSettings(request, request.hasInitImage ? delayMs : 750);
  const key = warmKeyForRequest(request);
  const resultKey = warmResultKeyForRequest(request);
  if (backgroundWarmResult && backgroundWarmResult.key !== key) {
    backgroundWarmResult = null;
  }
  if (backgroundWarmResult && backgroundWarmResult.resultKey !== resultKey) {
    backgroundWarmResult = null;
  }
  if (backgroundWarmPromise) {
    if (backgroundWarmKey && (backgroundWarmKey !== key || backgroundWarmResultKey !== resultKey)) {
      cancelBackgroundWarm("Settings changed; restarting background warmup");
    }
  }
  warmScheduleTimer = setTimeout(() => {
    warmScheduleTimer = 0;
    startBackgroundWarmForCurrentSettings();
  }, delayMs);
}

function takeReusableWarmResult(request) {
  const key = warmKeyForRequest(request);
  const resultKey = warmResultKeyForRequest(request);
  if (!backgroundWarmResult || backgroundWarmResult.key !== key) return null;
  if (backgroundWarmResult.resultKey !== resultKey) {
    backgroundWarmResult = null;
    return null;
  }
  const result = backgroundWarmResult;
  backgroundWarmResult = null;
  return result;
}

function generationResultKeyForRequest(request, initImageCacheKey = "") {
  const seed = Number.isFinite(Number(request.seed)) ? Math.trunc(Number(request.seed)) : request.seed;
  return JSON.stringify({
    prompt: request.prompt,
    width: request.width,
    height: request.height,
    steps: request.numSteps,
    seed,
    backend: request.transformerBackend,
    hasInitImage: request.hasInitImage,
    initImageKey: request.hasInitImage ? (initImageCacheKey || request.initImageKey) : undefined,
    strength: request.hasInitImage ? request.strength : undefined,
    strengthCurve: request.hasInitImage ? request.strengthCurve : undefined,
    effectiveStrength: request.hasInitImage
      ? Number(effectiveImg2ImgStrength(request.strength, request.strengthCurve).toFixed(6))
      : undefined,
    fitMode: request.hasInitImage ? request.fitMode : undefined,
    previewRenderMaxSize: request.previewRenderMaxSize,
    previewDecodeMaxSize: request.previewDecodeMaxSize,
    speed: speedCacheSignature(request.speed),
  });
}

function cloneImageData(imageData) {
  if (!imageData) return null;
  return new ImageData(new Uint8ClampedArray(imageData.data), imageData.width, imageData.height);
}

function cloneGenerationResult(result) {
  const copy = {
    ...result,
    timings: result.timings ? { ...result.timings } : {},
    transformerDetails: result.transformerDetails ? {
      ...result.transformerDetails,
      config: result.transformerDetails.config ? { ...result.transformerDetails.config } : result.transformerDetails.config,
      load: result.transformerDetails.load ? { ...result.transformerDetails.load } : result.transformerDetails.load,
      summary: result.transformerDetails.summary ? { ...result.transformerDetails.summary } : result.transformerDetails.summary,
    } : result.transformerDetails,
    customKernels: result.customKernels ? { ...result.customKernels } : result.customKernels,
    img2img: result.img2img ? { ...result.img2img } : result.img2img,
    previewRender: result.previewRender ? { ...result.previewRender } : result.previewRender,
    previewDecode: result.previewDecode ? { ...result.previewDecode } : result.previewDecode,
  };
  if (result.imageData) copy.imageData = cloneImageData(result.imageData);
  if (result.imageBlob) copy.imageBlob = result.imageBlob;
  return copy;
}

function takeCachedGenerationResult(cacheKey) {
  if (!cacheKey || urlFlag("noResultCache")) return null;
  const entry = generationResultCache.get(cacheKey);
  if (!entry) return null;
  generationResultCache.delete(cacheKey);
  generationResultCache.set(cacheKey, entry);
  const result = cloneGenerationResult(entry.result);
  result.resultCacheSource = "memory";
  const originalTimings = entry.result.timings || {};
  result.timings = {
    ...(result.timings || {}),
    cachedOriginalBrowserSeconds: originalTimings.totalBrowserSeconds,
    cachedOriginalTransformerSeconds: originalTimings.transformerSeconds,
    cachedOriginalVaeSeconds: originalTimings.vaeSeconds,
    totalBrowserSeconds: 0,
    transformerSeconds: 0,
    textEncoderSeconds: 0,
    textEncoderCacheSource: "skipped-result-cache",
    textEncoderCacheSeconds: 0,
    vaeEncoderSeconds: result.img2img ? 0 : undefined,
    vaeEncoderCacheSource: result.img2img ? "skipped-result-cache" : undefined,
    vaeSeconds: 0,
  };
  result.transformerDetails = null;
  return { result, seqLen: entry.seqLen };
}

function rememberGenerationResult(cacheKey, result, seqLen) {
  if (!cacheKey || urlFlag("noResultCache") || !result?.imageData) return;
  generationResultCache.set(cacheKey, {
    result: cloneGenerationResult(result),
    seqLen,
    savedAt: performance.now(),
  });
  const maxEntries = Math.max(1, Math.trunc(Number(urlDefaults.get("resultCacheEntries") || 4)));
  while (generationResultCache.size > maxEntries) {
    const oldestKey = generationResultCache.keys().next().value;
    generationResultCache.delete(oldestKey);
  }
}

function loadImageElement(file) {
  return new Promise((resolve, reject) => {
    const url = URL.createObjectURL(file);
    const image = new Image();
    image.onload = () => resolve({ image, url });
    image.onerror = () => {
      URL.revokeObjectURL(url);
      reject(new Error("Could not decode input image"));
    };
    image.src = url;
  });
}

function drawImageToCanvas(image, width, height, fitMode) {
  const canvas = document.createElement("canvas");
  canvas.width = width;
  canvas.height = height;
  const context = canvas.getContext("2d", { willReadFrequently: true });
  context.fillStyle = "#ffffff";
  context.fillRect(0, 0, width, height);
  if (fitMode === "stretch") {
    context.drawImage(image, 0, 0, width, height);
    return canvas;
  }
  const scale = fitMode === "contain"
    ? Math.min(width / image.naturalWidth, height / image.naturalHeight)
    : Math.max(width / image.naturalWidth, height / image.naturalHeight);
  const drawWidth = image.naturalWidth * scale;
  const drawHeight = image.naturalHeight * scale;
  const dx = (width - drawWidth) / 2;
  const dy = (height - drawHeight) / 2;
  context.drawImage(image, dx, dy, drawWidth, drawHeight);
  return canvas;
}

async function prepareInitImage(width, height, fitMode) {
  const file = initImageInput.files?.[0];
  if (!file) return null;
  const preparedKey = `${width}x${height}|${fitMode}`;
  const existingFileCache = preparedInitImageCache.get(file);
  if (existingFileCache?.has(preparedKey)) {
    const cached = existingFileCache.get(preparedKey);
    return { ...cached, sourceCache: "memory" };
  }
  const { image, url } = await loadImageElement(file);
  URL.revokeObjectURL(url);
  const canvas = drawImageToCanvas(image, width, height, fitMode);
  const imageData = canvas.getContext("2d", { willReadFrequently: true }).getImageData(0, 0, width, height);
  const rgba = imageData.data;
  const values = new Float32Array(width * height * 3);
  const plane = width * height;
  let hash = 2166136261 >>> 0;
  for (let pixel = 0; pixel < plane; pixel++) {
    const src = pixel * 4;
    hash ^= rgba[src];
    hash = Math.imul(hash, 16777619) >>> 0;
    hash ^= rgba[src + 1];
    hash = Math.imul(hash, 16777619) >>> 0;
    hash ^= rgba[src + 2];
    hash = Math.imul(hash, 16777619) >>> 0;
    hash ^= rgba[src + 3];
    hash = Math.imul(hash, 16777619) >>> 0;
    values[pixel] = rgba[src] / 127.5 - 1;
    values[plane + pixel] = rgba[src + 1] / 127.5 - 1;
    values[plane * 2 + pixel] = rgba[src + 2] / 127.5 - 1;
  }
  const pixelHash = hash.toString(16).padStart(8, "0");
  const prepared = {
    data: values,
    sourceRgba: new Uint8ClampedArray(rgba),
    sourceWidth: image.naturalWidth,
    sourceHeight: image.naturalHeight,
    sourceCache: "prepared",
    cacheKey: [
      file.name,
      file.size,
      file.lastModified || 0,
      `${image.naturalWidth}x${image.naturalHeight}`,
      `${width}x${height}`,
      fitMode,
      pixelHash,
    ].join("|"),
  };
  const fileCache = existingFileCache || new Map();
  fileCache.set(preparedKey, prepared);
  preparedInitImageCache.set(file, fileCache);
  return prepared;
}

function shouldBypassSourceOnly(request) {
  return request.hasInitImage &&
    !urlFlag("noSourceBypass") &&
    effectiveImg2ImgStrength(request.strength, request.strengthCurve) <= 0;
}

function sourceOnlyResult(request, initImage, totalSeconds) {
  const effectiveStrength = effectiveImg2ImgStrength(request.strength, request.strengthCurve);
  return {
    width: request.width,
    height: request.height,
    imageData: new ImageData(new Uint8ClampedArray(initImage.sourceRgba), request.width, request.height),
    imageBytes: request.width * request.height * 4,
    mode: "image-to-image",
    seed: request.seed,
    transformerBackend: request.transformerBackend,
    customKernels: { fullImageBackend: "source-bypass" },
    timings: {
      totalBrowserSeconds: Number(totalSeconds.toFixed(3)),
      customKernelStatusSeconds: 0,
      transformerSeconds: 0,
      textEncoderSeconds: 0,
      textEncoderCacheSource: "skipped-source-only",
      textEncoderCacheSeconds: 0,
      vaeEncoderSeconds: 0,
      vaeEncoderCacheSource: "source-bypass",
      vaeSeconds: 0,
    },
    img2img: {
      strength: request.strength,
      effectiveStrength: Number(effectiveStrength.toFixed(6)),
      curve: request.strengthCurve,
      startT: 0,
      denoiseSteps: 0,
      requestedSteps: request.numSteps,
      stepPolicy: request.speed.img2imgStepPolicy || "full",
    },
  };
}

function shouldPreviewRenderInitImage(request) {
  if (!request?.hasInitImage) return false;
  if (urlFlag("noImg2ImgPreviewRender")) return false;
  if (urlFlag("img2imgPreviewRender") || urlFlag("img2imgPreview")) return true;
  const requestedMax = Math.max(0, Math.trunc(Number(request.previewRenderMaxSize || 0)));
  return Boolean(requestedMax && Math.max(request.width, request.height) > requestedMax);
}

function shouldPreviewRenderRequest(request) {
  return !request?.hasInitImage || shouldPreviewRenderInitImage(request);
}

function plannedRenderSize(width, height, maxSize, enabled = true) {
  const requestedMax = Math.max(0, Math.trunc(Number(maxSize || 0)));
  if (!enabled || !requestedMax || Math.max(width, height) <= requestedMax) {
    return { width, height };
  }
  const scale = requestedMax / Math.max(width, height);
  return {
    width: Math.max(16, Math.floor((width * scale) / 16) * 16),
    height: Math.max(16, Math.floor((height * scale) / 16) * 16),
  };
}

function plannedRenderSizeForRequest(request) {
  return plannedRenderSize(
    request.width,
    request.height,
    request.previewRenderMaxSize,
    shouldPreviewRenderRequest(request),
  );
}

function roundUpToMultiple(value, multiple) {
  const safeMultiple = Math.max(1, Math.trunc(Number(multiple || 1)));
  return Math.ceil(Number(value || 0) / safeMultiple) * safeMultiple;
}

function attentionMaskActiveTokenCount(values, seqLen) {
  if (!values || values.length < seqLen) return seqLen;
  for (let index = seqLen - 1; index >= 0; index--) {
    if (Number(values[index]) !== 0) return index + 1;
  }
  return 1;
}

function plannedCustomTextTokens(request, attentionMask, seqLen) {
  const requestedLimit = Math.max(0, Math.trunc(Number(request.speed.customTextTokenLimit || 0)));
  if (!requestedLimit) return seqLen;
  const minTokens = Math.max(1, Math.trunc(Number(request.speed.customMinTextTokens || 64)));
  const activeTokens = attentionMaskActiveTokenCount(attentionMask, seqLen);
  return Math.min(seqLen, Math.max(minTokens, roundUpToMultiple(Math.min(activeTokens, requestedLimit), 16)));
}

function readRequest() {
  const width = Number($("width").value);
  const height = Number($("height").value);
  const fitMode = $("fit-mode").value;
  const requestedSeed = Number($("seed").value);
  const seed = Number.isFinite(requestedSeed) && requestedSeed >= 0
    ? Math.trunc(requestedSeed)
    : Math.floor(Math.random() * 0x7fffffff);
  const speed = selectedSpeedConfig(width, height);
  const selectedPreviewRenderMaxSize = Number($("render-max").value) || 0;
  const selectedPreviewDecodeMaxSize = Number($("decode-max").value) || 0;
  return {
    prompt: $("prompt").value,
    width,
    height,
    seed,
    requestedSeed,
    numSteps: Number($("steps").value),
    transformerBackend: $("backend").value,
    hasInitImage: Boolean(initImageInput.files?.[0]),
    initImageKey: currentInitImageKey(width, height, fitMode),
    strength: Number(strengthEl.value),
    strengthCurve: strengthCurveEl.value,
    fitMode,
    previewRenderMaxSize: selectedPreviewRenderMaxSize || speed.autoPreviewRenderMaxSize || 0,
    previewDecodeMaxSize: selectedPreviewDecodeMaxSize || speed.autoPreviewDecodeMaxSize || 0,
    speed,
  };
}

function buildGenerateParams(request, tokenized, initImage) {
  const seqLen = tokenized.inputIds?.length || 512;
  const plannedTextTokens = plannedCustomTextTokens(request, tokenized.attentionMask, seqLen);
  const plannedDecodeMax = plannedDecodeMaxForRequest(request);
  const defaultVaeChunkSize = defaultVaeChunkSizeForDecodeMax(plannedDecodeMax);
  return {
    inputIds: tokenized.inputIds,
    attentionMask: tokenized.attentionMask,
    width: request.width,
    height: request.height,
    seed: request.seed,
    numSteps: request.numSteps,
    cacheSessions: true,
    gpuDenoise: true,
    cacheTextContext: true,
    persistentTextContextCache: !urlFlag("noPromptCache"),
    promptCacheKey: tokenized.promptCacheKey,
    textContextUrl: staticTextContextUrlForPrompt(request.prompt),
    textProjectionUrl: staticTextProjectionUrlForPrompt(request.prompt, plannedTextTokens),
    transformerBackend: request.transformerBackend,
    requireCustomTransformer: request.transformerBackend === "custom-lowbit-webgpu",
    returnImageData: true,
    returnImageBlob: false,
    gpuVaeHandoff: urlFlag("gpuVaeHandoff"),
    maxGpuHandoffSeq: Number(urlDefaults.get("maxGpuHandoffSeq") || 4096),
    vaeAttentionChunkSize: Number(urlDefaults.get("vaeChunk") || 0) || defaultVaeChunkSize,
    maxAutoVaeAttentionChunkSeq: Number(urlDefaults.get("maxAutoVaeChunkSeq") || 0),
    previewRenderMaxSize: request.previewRenderMaxSize,
    previewRenderInitImage: shouldPreviewRenderInitImage(request),
    previewDecodeMaxSize: request.previewDecodeMaxSize,
    ...(initImage ? {
      initImage: initImage.data,
      initImageCacheKey: initImage.cacheKey || request.initImageKey,
      cacheVaeEncoder: !urlFlag("noVaeEncoderCache"),
      strength: request.strength,
      strengthCurve: request.strengthCurve,
    } : {}),
    ...request.speed,
  };
}

async function prepareGenerationInputs(request, init) {
  const seqLen = Number(init.config.text_seq_len || 512);
  const renderSize = plannedRenderSizeForRequest(request);
  const [tokenized, initImage] = await Promise.all([
    tokenizePrompt(request.prompt, seqLen),
    request.hasInitImage ? prepareInitImage(renderSize.width, renderSize.height, request.fitMode) : Promise.resolve(null),
  ]);
  const imageTokens = Math.ceil(renderSize.width / 16) * Math.ceil(renderSize.height / 16);
  const textTokens = plannedCustomTextTokens(request, tokenized.attentionMask, seqLen);
  if (request.transformerBackend === "custom-lowbit-webgpu" && imageTokens + textTokens > 4608) {
    throw new Error(`Custom WebGPU backend supports up to 4608 joint tokens; requested ${imageTokens + textTokens}`);
  }
  return { tokenized, initImage, seqLen };
}

function shouldUseCssPreviewUpscale(result, imageDataWidth, imageDataHeight) {
  if (!urlFlag("cssPreviewUpscale")) return false;
  if (urlFlag("backingUpscale") || urlFlag("noCssPreviewUpscale")) return false;
  if (imageDataWidth === result.width && imageDataHeight === result.height) return false;
  return Boolean(result.previewRender || result.previewDecode);
}

function displayGenerationResult(result, elapsed, seqLen, heading = "Elapsed", extraLines = [], request = null, options = {}) {
  if (currentImageUrl) URL.revokeObjectURL(currentImageUrl);
  currentImageUrl = null;
  if (result.imageData) {
    const imageDataWidth = result.imageDataWidth || result.width;
    const imageDataHeight = result.imageDataHeight || result.height;
    const cssPreviewUpscale = shouldUseCssPreviewUpscale(result, imageDataWidth, imageDataHeight);
    canvasEl.width = cssPreviewUpscale ? imageDataWidth : result.width;
    canvasEl.height = cssPreviewUpscale ? imageDataHeight : result.height;
    canvasEl.style.width = cssPreviewUpscale ? `${result.width}px` : "";
    canvasEl.style.height = cssPreviewUpscale ? `${result.height}px` : "";
    const context = canvasEl.getContext("2d");
    if (cssPreviewUpscale || (imageDataWidth === result.width && imageDataHeight === result.height)) {
      context.putImageData(result.imageData, 0, 0);
    } else {
      const tempCanvas = document.createElement("canvas");
      tempCanvas.width = imageDataWidth;
      tempCanvas.height = imageDataHeight;
      tempCanvas.getContext("2d").putImageData(result.imageData, 0, 0);
      context.imageSmoothingEnabled = true;
      context.imageSmoothingQuality = "high";
      context.clearRect(0, 0, result.width, result.height);
      context.drawImage(tempCanvas, 0, 0, result.width, result.height);
    }
    canvasEl.hidden = false;
    imageEl.hidden = true;
  } else if (result.imageBlob) {
    currentImageUrl = URL.createObjectURL(result.imageBlob);
    imageEl.src = currentImageUrl;
    imageEl.hidden = false;
    canvasEl.hidden = true;
  } else {
    throw new Error("Generation did not return image pixels");
  }
  placeholderEl.hidden = true;
  const timings = result.timings || {};
  const transformerConfig = result.transformerDetails?.config || {};
  const transformerLoad = result.transformerDetails?.load || {};
  const transformerSummary = result.transformerDetails?.summary || {};
  const phaseProfile = transformerSummary.phase_profile_ms || {};
  setStatus([
    `${heading}: ${elapsed.toFixed(3)}s`,
    ...extraLines,
    `Mode: ${result.mode || "text-to-image"}`,
    seedLineForResult(result, request),
    result.resultCacheSource ? `Result cache: ${result.resultCacheSource}${timings.cachedOriginalBrowserSeconds !== undefined ? ` original=${timings.cachedOriginalBrowserSeconds}s` : ""}${timings.cachedOriginalTransformerSeconds !== undefined ? ` transformer=${timings.cachedOriginalTransformerSeconds}s` : ""}${timings.cachedOriginalVaeSeconds !== undefined ? ` vae=${timings.cachedOriginalVaeSeconds}s` : ""}` : "",
    `Browser: ${timings.totalBrowserSeconds ?? "?"}s`,
    timings.customKernelStatusSeconds ? `Kernel status: ${timings.customKernelStatusSeconds}s` : "",
    `Transformer: ${timings.transformerSeconds ?? "?"}s`,
    transformerLoad.total_ms !== undefined ? `Transformer assets: ${(transformerLoad.total_ms / 1000).toFixed(3)}s` : "",
    transformerLoad.stage_setup_ms !== undefined ? `Transformer stage setup: ${(transformerLoad.stage_setup_ms / 1000).toFixed(3)}s` : "",
    transformerSummary.median_step_ms !== undefined ? `Transformer median step: ${(transformerSummary.median_step_ms / 1000).toFixed(3)}s` : "",
    transformerConfig.profilePhases ? `Phase time/input: ${((phaseProfile.time_input_ms || 0) / 1000).toFixed(3)}s` : "",
    transformerConfig.profilePhases ? `Phase double: ${((phaseProfile.double_blocks_ms || 0) / 1000).toFixed(3)}s` : "",
    transformerConfig.profilePhases ? `Phase single: ${((phaseProfile.single_blocks_ms || 0) / 1000).toFixed(3)}s` : "",
    transformerConfig.profileSingleParts ? `Phase single linear1: ${((phaseProfile.single_linear1_ms || 0) / 1000).toFixed(3)}s` : "",
    transformerConfig.profileSingleParts ? `Phase single attention: ${((phaseProfile.single_attention_ms || 0) / 1000).toFixed(3)}s` : "",
    transformerConfig.profileSingleParts ? `Phase single MLP: ${((phaseProfile.single_mlp_ms || 0) / 1000).toFixed(3)}s` : "",
    transformerConfig.profilePhases ? `Phase final/update: ${((phaseProfile.final_update_ms || 0) / 1000).toFixed(3)}s` : "",
    transformerLoad.readback_ms !== undefined ? `Transformer readback: ${(transformerLoad.readback_ms / 1000).toFixed(3)}s` : "",
    transformerLoad.text_projection_init_ms !== undefined ? `Text projection: ${(transformerLoad.text_projection_init_ms / 1000).toFixed(3)}s cache=${transformerLoad.text_projection_cache_source || (transformerLoad.text_projection_cache_hit ? "hit" : "miss")}${transformerLoad.text_projection_persistent_ms ? ` db=${(transformerLoad.text_projection_persistent_ms / 1000).toFixed(3)}s` : ""}` : "",
    transformerConfig.textTokens && transformerConfig.textTokens !== seqLen ? `Transformer text tokens: ${transformerConfig.textTokens}/${seqLen}` : "",
    transformerConfig.doubleBlockCount !== undefined && transformerConfig.singleBlockCount !== undefined && (
      transformerConfig.doubleBlockCount !== 5 || transformerConfig.singleBlockCount !== 20
    ) ? `Blocks: double ${transformerConfig.doubleBlockCount}/5, single ${transformerConfig.singleBlockCount}/20` : "",
    `Text: ${timings.textEncoderSeconds ?? "?"}s cache=${timings.textEncoderCacheSource || "?"}${timings.textEncoderCacheSeconds ? ` db=${timings.textEncoderCacheSeconds}s` : ""}`,
    result.img2img ? `VAE Encode: ${timings.vaeEncoderSeconds ?? "?"}s cache=${timings.vaeEncoderCacheSource || "?"}` : "",
    `VAE: ${timings.vaeSeconds ?? "?"}s`,
    result.img2img ? `Strength: ${result.img2img.strength} effective=${result.img2img.effectiveStrength} curve=${result.img2img.curve} startT=${result.img2img.startT} steps=${result.img2img.denoiseSteps}${result.img2img.requestedSteps && result.img2img.requestedSteps !== result.img2img.denoiseSteps ? `/${result.img2img.requestedSteps}` : ""}${result.img2img.stepPolicy && result.img2img.stepPolicy !== "full" ? ` policy=${result.img2img.stepPolicy}` : ""}` : "",
    result.previewRender ? `Preview render: ${result.previewRender.renderWidth}x${result.previewRender.renderHeight} -> ${result.width}x${result.height}` : "",
    result.previewDecode ? `Preview decode: ${result.previewDecode.decodeWidth}x${result.previewDecode.decodeHeight} -> ${result.width}x${result.height}` : "",
    shouldUseCssPreviewUpscale(result, result.imageDataWidth || result.width, result.imageDataHeight || result.height) ? `Canvas backing: ${result.imageDataWidth || result.width}x${result.imageDataHeight || result.height} CSS-upscaled` : "",
    timings.imageTensorToRgbaSeconds !== undefined ? `Image convert: ${timings.imageTensorToRgbaSeconds}s` : "",
    timings.imageDataSeconds !== undefined ? `ImageData: ${timings.imageDataSeconds}s` : "",
    transformerConfig.approxReusePredEvery ? `Approx reused steps: ${transformerConfig.approxReusedSteps}/${transformerConfig.steps}` : "",
    transformerConfig.approxReusePredEvery && transformerConfig.approxPredictionMode !== "raw" ? `Approx mode: ${transformerConfig.approxPredictionMode} scale=${transformerConfig.approxAbScale}` : "",
    transformerConfig.approxCollapsedUpdateDispatches ? `Collapsed update dispatches: ${transformerConfig.approxCollapsedUpdateDispatches}` : "",
    transformerConfig.skippedSingleBlocks ? `Skipped single blocks: ${transformerConfig.skippedSingleBlocks}` : "",
    transformerConfig.reusedSingleTailBlocks ? `Reused single tail blocks: ${transformerConfig.reusedSingleTailBlocks}` : "",
    transformerConfig.stepSubmitFusion ? "Step submit fusion: on" : "",
    transformerConfig.skippedOptionalSetupBytes ? `Skipped optional setup: ${formatMiB(transformerConfig.skippedOptionalSetupBytes)}${transformerConfig.skippedOptionalPipelines ? `, ${transformerConfig.skippedOptionalPipelines} pipelines` : ""}` : "",
    transformerConfig.linearRowBlock && transformerConfig.linearRowBlock !== 32 ? `Linear row block: ${transformerConfig.linearRowBlock}` : "",
    transformerConfig.singleAttentionKernel && transformerConfig.singleAttentionKernel !== "tiled" ? `Single attention kernel: ${transformerConfig.singleAttentionKernel}` : "",
    transformerConfig.singleComputePass ? "Compute pass mode: single" : "",
    transformerConfig.singleQkNormStorage && transformerConfig.singleQkNormStorage !== "f32" ? `Q/K norm storage: ${transformerConfig.singleQkNormStorage}` : "",
    `Backend: ${result.transformerBackend}`,
    `Full image backend: ${result.customKernels?.fullImageBackend || "unknown"}`,
    `Image: ${result.imageBytes ?? result.pngBytes ?? 0} bytes${result.pngBytes ? " PNG" : " RGBA"}`,
  ]);
  if (options.addToGallery !== false && request) {
    rememberGalleryResult(result, elapsed, request, heading);
  }
}

async function generate() {
  if (!bootReady) throw new Error("Model assets are not loaded yet.");
  const requestedStarted = performance.now();
  const request = readRequest();
  runButton.disabled = true;
  setButtonDisabled(warmButton, true);
  abortButton.disabled = false;
  imageEl.hidden = true;
  canvasEl.hidden = true;
  placeholderEl.hidden = false;
  placeholderEl.textContent = "Running";
  setStatus([
    request.hasInitImage ? "Preparing image" : "Tokenizing",
    seedLineForRequest(request),
    `Backend: ${request.transformerBackend}`,
  ]);

  if (shouldBypassSourceOnly(request)) {
    cancelBackgroundWarm();
    const prepareStarted = performance.now();
    const initImage = await prepareInitImage(request.width, request.height, request.fitMode);
    const prepareSeconds = (performance.now() - prepareStarted) / 1000;
    const totalSeconds = (performance.now() - requestedStarted) / 1000;
    displayGenerationResult(sourceOnlyResult(request, initImage, totalSeconds), totalSeconds, 512, "Elapsed", [
      `Prepare: ${prepareSeconds.toFixed(3)}s${initImage?.sourceCache ? ` source=${initImage.sourceCache}` : ""}`,
      "Source-only bypass: no text encoder, transformer, VAE encoder, or VAE decoder",
    ], request);
    return;
  }

  const earlyResultCacheKey = !request.hasInitImage ? generationResultKeyForRequest(request) : "";
  const earlyCachedResult = takeCachedGenerationResult(earlyResultCacheKey);
  if (earlyCachedResult) {
    cancelBackgroundWarm();
    const elapsed = (performance.now() - requestedStarted) / 1000;
    displayGenerationResult(earlyCachedResult.result, elapsed, earlyCachedResult.seqLen, "Ready from result cache", [
      `Click-to-image: ${elapsed.toFixed(3)}s`,
      "Exact fixed-seed request reused from memory",
    ], request);
    return;
  }

  const warmWait = await waitForBackgroundWarm(request);
  const warmWaitSeconds = warmWait.seconds || 0;
  const reusableWarmResult = warmWait.result || null;
  if (reusableWarmResult && !reusableWarmResult.warmProfile && request.speed.requestedProfile !== "progressive") {
    const clickTotal = (performance.now() - requestedStarted) / 1000;
    rememberGenerationResult(earlyResultCacheKey || generationResultKeyForRequest(request), reusableWarmResult.result, reusableWarmResult.seqLen);
    displayGenerationResult(reusableWarmResult.result, reusableWarmResult.elapsed, reusableWarmResult.seqLen, "Ready from warm", [
      warmWaitSeconds ? `Queued warm wait: ${warmWaitSeconds.toFixed(3)}s` : "",
      `Click-to-image: ${clickTotal.toFixed(3)}s`,
      "Reused hidden warm result",
    ], request);
    return;
  }
  const textContextPrepareWaitSeconds = await waitForBackgroundTextContextPrepare(request);
  const transformerSetupPrepareWaitSeconds = await waitForBackgroundTransformerSetupPrepare(request);
  const vaeEncoderPrepareWaitSeconds = await waitForBackgroundVaeEncoderPrepare(request);
  const vaePrepareWaitSeconds = await waitForBackgroundVaePrepare(request);
  const hasPrepareWait = Boolean(
    warmWaitSeconds ||
    textContextPrepareWaitSeconds ||
    transformerSetupPrepareWaitSeconds ||
    vaeEncoderPrepareWaitSeconds ||
    vaePrepareWaitSeconds
  );
  const { engine, init } = await initEngine();

  const prepareStarted = performance.now();
  const { tokenized, initImage, seqLen } = await prepareGenerationInputs(request, init);
  const prepareSeconds = (performance.now() - prepareStarted) / 1000;
  const resultCacheKey = request.hasInitImage
    ? generationResultKeyForRequest(request, initImage?.cacheKey)
    : earlyResultCacheKey;
  const cachedAfterPrepare = takeCachedGenerationResult(resultCacheKey);
  if (cachedAfterPrepare) {
    const elapsed = (performance.now() - requestedStarted) / 1000;
    displayGenerationResult(cachedAfterPrepare.result, elapsed, cachedAfterPrepare.seqLen, "Ready from result cache", [
      `Prepare: ${prepareSeconds.toFixed(3)}s${initImage?.sourceCache ? ` source=${initImage.sourceCache}` : ""}`,
      `Click-to-image: ${elapsed.toFixed(3)}s`,
      "Exact fixed-seed request reused from memory",
    ], request);
    return;
  }
  const plannedTextTokens = plannedCustomTextTokens(request, tokenized.attentionMask, seqLen);
  setStatus([
    "Generating",
    `Mode: ${initImage ? "Image to image" : "Text to image"}`,
    seedLineForRequest(request),
    `Tokens: ${tokenized.tokenCount}/${seqLen}`,
    plannedTextTokens < seqLen ? `Transformer text tokens: ${plannedTextTokens}/${seqLen}` : "",
    initImage ? `Strength: ${request.strength.toFixed(2)} effective=${formatStrengthValue(effectiveImg2ImgStrength(request.strength, request.strengthCurve))} curve=${request.strengthCurve}` : "",
    initImage && request.speed.img2imgStepPolicy === "adaptive" ? `Img2img steps: adaptive up to ${request.numSteps}` : "",
    `Backend: ${request.transformerBackend}`,
    `Speed Profile: ${speedProfileLabel(request.speed)}`,
    request.speed.customApproxReusePredEvery ? `Approx cache: every ${request.speed.customApproxReusePredEvery} steps` : "",
    request.speed.customApproxReusePredEvery && request.speed.customApproxPredictionMode !== "raw" ? `Approx mode: ${request.speed.customApproxPredictionMode}` : "",
    request.previewRenderMaxSize ? `${request.speed.requestedProfile === "progressive" ? "Final preview render" : "Preview render"}: ${request.previewRenderMaxSize}px max` : "",
    request.previewDecodeMaxSize ? `${request.speed.requestedProfile === "progressive" ? "Final preview decode" : "Preview decode"}: ${request.previewDecodeMaxSize}px max` : "",
  ]);

  const started = performance.now();
  const shouldRunProgressivePreview = request.speed.requestedProfile === "progressive" &&
    !initImage &&
    Math.max(request.width, request.height) > 256;
  if (shouldRunProgressivePreview) {
    const progressivePreviewProfile = progressivePreviewProfileForRequest(request);
    const previewRequest = requestWithSpeedProfile(request, progressivePreviewProfile, { useSelectedCaps: false });
    const previewStarted = performance.now();
    const previewFromWarm = reusableWarmResult?.warmProfile === progressivePreviewProfile;
    const previewResult = previewFromWarm
      ? reusableWarmResult.result
      : await engine.generateImage(buildGenerateParams(previewRequest, tokenized, initImage));
    const previewComputeElapsed = previewFromWarm ? reusableWarmResult.elapsed : (performance.now() - previewStarted) / 1000;
    const previewVisibleElapsed = (performance.now() - previewStarted) / 1000;
    displayGenerationResult(previewResult, previewFromWarm ? previewVisibleElapsed : previewComputeElapsed, seqLen, "Preview ready", [
      previewFromWarm ? "Reused hidden warm preview" : "",
      previewFromWarm ? `Preview warm compute: ${previewComputeElapsed.toFixed(3)}s` : "",
      "Refining final image",
    ], previewRequest, { addToGallery: false });

    const progressiveFinalProfile = progressiveFinalProfileForRequest(request);
    const finalRequest = requestWithSpeedProfile(request, progressiveFinalProfile, { useSelectedCaps: true });
    setStatus([
      `Preview shown: ${previewVisibleElapsed.toFixed(3)}s`,
      previewFromWarm ? `Preview warm compute: ${previewComputeElapsed.toFixed(3)}s` : "",
      "Refining final image",
      seedLineForRequest(request),
      `Backend: ${request.transformerBackend}`,
      `Final Profile: ${speedProfileLabel(finalRequest.speed)}`,
      finalRequest.previewRenderMaxSize ? `Final preview render: ${finalRequest.previewRenderMaxSize}px max` : "",
      finalRequest.previewDecodeMaxSize ? `Final preview decode: ${finalRequest.previewDecodeMaxSize}px max` : "",
    ]);
    const finalResult = await engine.generateImage(buildGenerateParams(finalRequest, tokenized, initImage));
    const totalElapsed = (performance.now() - started) / 1000;
    const clickTotal = (performance.now() - requestedStarted) / 1000;
    rememberGenerationResult(resultCacheKey, finalResult, seqLen);
    displayGenerationResult(finalResult, totalElapsed, seqLen, "Final ready", [
      `Preview first: ${previewVisibleElapsed.toFixed(3)}s`,
      previewFromWarm ? `Preview warm compute: ${previewComputeElapsed.toFixed(3)}s` : "",
      `Final Profile: ${speedProfileLabel(finalRequest.speed)}`,
      `Prepare: ${prepareSeconds.toFixed(3)}s${initImage?.sourceCache ? ` source=${initImage.sourceCache}` : ""}`,
      warmWaitSeconds ? `Queued warm wait: ${warmWaitSeconds.toFixed(3)}s` : "",
      textContextPrepareWaitSeconds ? `Text prepare wait: ${textContextPrepareWaitSeconds.toFixed(3)}s` : "",
      transformerSetupPrepareWaitSeconds ? `Transformer setup prepare wait: ${transformerSetupPrepareWaitSeconds.toFixed(3)}s` : "",
      vaeEncoderPrepareWaitSeconds ? `VAE encoder prepare wait: ${vaeEncoderPrepareWaitSeconds.toFixed(3)}s` : "",
      vaePrepareWaitSeconds ? `VAE prepare wait: ${vaePrepareWaitSeconds.toFixed(3)}s` : "",
      hasPrepareWait ? `Click-to-final: ${clickTotal.toFixed(3)}s` : "",
    ], request);
    return;
  }

  const result = await engine.generateImage(buildGenerateParams(request, tokenized, initImage));
  const elapsed = (performance.now() - started) / 1000;
  const clickTotal = (performance.now() - requestedStarted) / 1000;
  rememberGenerationResult(resultCacheKey, result, seqLen);
  displayGenerationResult(result, elapsed, seqLen, "Elapsed", [
    `Prepare: ${prepareSeconds.toFixed(3)}s${initImage?.sourceCache ? ` source=${initImage.sourceCache}` : ""}`,
    warmWaitSeconds ? `Queued warm wait: ${warmWaitSeconds.toFixed(3)}s` : "",
    textContextPrepareWaitSeconds ? `Text prepare wait: ${textContextPrepareWaitSeconds.toFixed(3)}s` : "",
    transformerSetupPrepareWaitSeconds ? `Transformer setup prepare wait: ${transformerSetupPrepareWaitSeconds.toFixed(3)}s` : "",
    vaeEncoderPrepareWaitSeconds ? `VAE encoder prepare wait: ${vaeEncoderPrepareWaitSeconds.toFixed(3)}s` : "",
    vaePrepareWaitSeconds ? `VAE prepare wait: ${vaePrepareWaitSeconds.toFixed(3)}s` : "",
    hasPrepareWait ? `Click-to-image: ${clickTotal.toFixed(3)}s` : "",
  ], request);
}

async function waitForBackgroundWarm(request) {
  const pending = backgroundWarmPromise;
  if (!pending) return { seconds: 0, result: takeReusableWarmResult(request) };
  const started = performance.now();
  const expectedWarmKey = warmKeyForRequest(request);
  const expectedResultKey = warmResultKeyForRequest(request);
  if (backgroundWarmKey && (backgroundWarmKey !== expectedWarmKey || backgroundWarmResultKey !== expectedResultKey)) {
    setStatus([
      "Stopping stale background warmup",
      "Current settings changed; generation will run with the new settings",
    ]);
    window.flux2Engine?.abortGeneration?.();
    try {
      await pending;
    } catch {
      // Stale warmup errors are expected when it is aborted.
    }
    return { seconds: 0, result: null };
  }
  setStatus([
    "Finishing background warmup",
    "Generation will start as soon as the warmed WebGPU state is ready",
  ]);
  try {
    await pending;
  } catch {
    // The foreground generation path will surface any real runtime issue.
  }
  return {
    seconds: (performance.now() - started) / 1000,
    result: takeReusableWarmResult(request),
  };
}

async function waitForBackgroundTextContextPrepare(request) {
  const pending = backgroundTextContextPreparePromise;
  if (!pending) return 0;
  const prepareRequest = backgroundPrepareRequestForRequest(request);
  const expectedKey = textContextPrepareKeyForRequest(prepareRequest);
  if (!backgroundTextContextPrepareKey || backgroundTextContextPrepareKey !== expectedKey) return 0;
  const started = performance.now();
  setStatus([
    "Finishing text context preparation",
    "Generation will start as soon as the prompt embedding cache is ready",
  ]);
  try {
    await pending;
  } catch {
    // The visible generation path will run the text encoder normally if preparation failed.
  }
  return (performance.now() - started) / 1000;
}

async function waitForBackgroundTransformerSetupPrepare(request) {
  const pending = backgroundTransformerSetupPreparePromise;
  if (!pending) return 0;
  const prepareRequest = backgroundPrepareRequestForRequest(request);
  const dispatchWarmup = shouldTransformerDispatchWarmupRequest(prepareRequest);
  const expectedKey = `${transformerSetupPrepareKeyForRequest(prepareRequest)}|dispatch=${dispatchWarmup ? 1 : 0}`;
  if (!backgroundTransformerSetupPrepareKey || backgroundTransformerSetupPrepareKey !== expectedKey) return 0;
  const started = performance.now();
  setStatus([
    "Finishing transformer setup preparation",
    "Generation will start as soon as cached custom WebGPU setup is ready",
  ]);
  try {
    await pending;
  } catch {
    // The visible generation path will build setup normally if preparation failed.
  }
  return (performance.now() - started) / 1000;
}

async function waitForBackgroundVaeEncoderPrepare(request) {
  const pending = backgroundVaeEncoderPreparePromise;
  if (!pending) return 0;
  const expectedKey = vaeEncoderPrepareKeyForRequest(request);
  if (!backgroundVaeEncoderPrepareKey || backgroundVaeEncoderPrepareKey !== expectedKey) return 0;
  const started = performance.now();
  setStatus([
    "Finishing VAE encoder preparation",
    "Generation will start as soon as the uploaded source latent is cached",
  ]);
  try {
    await pending;
  } catch {
    // The visible generation path will encode the source normally if preparation failed.
  }
  return (performance.now() - started) / 1000;
}

async function waitForBackgroundVaePrepare(request) {
  const pending = backgroundVaePreparePromise;
  if (!pending) return 0;
  const prepareRequest = backgroundPrepareRequestForRequest(request);
  const dispatchWarmup = shouldVaeDispatchWarmupRequest(prepareRequest);
  const expectedKey = `${vaePrepareKeyForRequest(prepareRequest)}|dispatch=${dispatchWarmup ? 1 : 0}`;
  if (!backgroundVaePrepareKey || backgroundVaePrepareKey !== expectedKey) return 0;
  const started = performance.now();
  setStatus([
    "Finishing VAE session preparation",
    "Generation will start as soon as cached decoder sessions are ready",
  ]);
  try {
    await pending;
  } catch {
    // The visible generation path will create sessions normally if preparation failed.
  }
  return (performance.now() - started) / 1000;
}

async function warmCurrentSettings({ background = false } = {}) {
  if (!canRunRuntimeWork()) throw new Error("Model assets are not loaded yet.");
  const request = readRequest();
  const { warmRequest, warmProfile } = warmPlanForRequest(request);
  const { engine, init } = await initEngine();
  const started = performance.now();
  if (!background) {
    runButton.disabled = true;
  } else {
    runButton.disabled = false;
  }
  setButtonDisabled(warmButton, true);
  abortButton.disabled = !background;
  if (!background) {
    placeholderEl.hidden = false;
    placeholderEl.textContent = "Warming";
  }
  setStatus([
    background ? "Preparing fast path in background" : "Warming current settings",
    `Seed: ${request.seed}`,
    `Backend: ${request.transformerBackend}`,
    `Speed Profile: ${warmProfile ? "progressive preview warm" : speedProfileLabel(request.speed)}`,
    warmRequest.previewRenderMaxSize ? `Preview render: ${warmRequest.previewRenderMaxSize}px max` : "",
    warmRequest.previewDecodeMaxSize ? `Preview decode: ${warmRequest.previewDecodeMaxSize}px max` : "",
  ]);
  const key = warmKeyForRequest(request);
  const resultKey = warmResultKeyForRequest(request);
  const { tokenized, initImage, seqLen } = await prepareGenerationInputs(warmRequest, init);
  const result = await engine.generateImage(buildGenerateParams(warmRequest, tokenized, initImage));
  const elapsed = (performance.now() - started) / 1000;
  const timings = result.timings || {};
  const transformerLoad = result.transformerDetails?.load || {};
  if (!background || !foregroundBusy) {
    setStatus([
      `Warm complete: ${elapsed.toFixed(3)}s`,
      timings.customKernelStatusSeconds ? `Kernel status: ${timings.customKernelStatusSeconds}s` : "",
      `Text: ${timings.textEncoderSeconds ?? "?"}s cache=${timings.textEncoderCacheSource || "?"}${timings.textEncoderCacheSeconds ? ` db=${timings.textEncoderCacheSeconds}s` : ""}`,
      `Transformer: ${timings.transformerSeconds ?? "?"}s`,
      transformerLoad.total_ms !== undefined ? `Transformer assets: ${(transformerLoad.total_ms / 1000).toFixed(3)}s` : "",
      transformerLoad.stage_setup_ms !== undefined ? `Transformer stage setup: ${(transformerLoad.stage_setup_ms / 1000).toFixed(3)}s` : "",
      transformerLoad.text_projection_init_ms !== undefined ? `Text projection: ${(transformerLoad.text_projection_init_ms / 1000).toFixed(3)}s cache=${transformerLoad.text_projection_cache_source || (transformerLoad.text_projection_cache_hit ? "hit" : "miss")}${transformerLoad.text_projection_persistent_ms ? ` db=${(transformerLoad.text_projection_persistent_ms / 1000).toFixed(3)}s` : ""}` : "",
      `VAE: ${timings.vaeSeconds ?? "?"}s`,
      result.previewRender ? `Preview render: ${result.previewRender.renderWidth}x${result.previewRender.renderHeight} -> ${result.width}x${result.height}` : "",
      result.previewDecode ? `Preview decode: ${result.previewDecode.decodeWidth}x${result.previewDecode.decodeHeight} -> ${result.width}x${result.height}` : "",
    ]);
  }
  if (!foregroundBusy) {
    runButton.disabled = false;
    setButtonDisabled(warmButton, false);
    abortButton.disabled = true;
  }
  return { key, resultKey, warmProfile, result, elapsed, seqLen, canReuseResult: background && !warmRequest.hasInitImage };
}

async function prepareInitialFastPath(request) {
  if (urlFlag("noInitialPrepare") || urlFlag("noAutowarm")) return false;
  const prepareRequest = backgroundPrepareRequestForRequest(request);
  const shouldPrepareAssets = shouldAssetPrepareRequest(prepareRequest);
  const shouldPrepareTransformer = shouldTransformerSetupPrepareRequest(prepareRequest);
  const shouldPrepareVae = shouldVaePrepareRequest(prepareRequest);
  if (!shouldPrepareAssets && !shouldPrepareTransformer && !shouldPrepareVae) return false;

  setStatus([
    "Preparing fast path",
    `Backend: ${prepareRequest.transformerBackend}`,
    `Speed Profile: ${speedProfileLabel(prepareRequest.speed)}`,
    prepareRequest.previewRenderMaxSize ? `Preview render: ${prepareRequest.previewRenderMaxSize}px max` : "",
    prepareRequest.previewDecodeMaxSize ? `Preview decode: ${prepareRequest.previewDecodeMaxSize}px max` : "",
  ]);
  setLoadPhase("Preparing fast path");

  if (shouldPrepareAssets) await prepareCustomAssetLoadEstimate(prepareRequest);
  startBackgroundAssetPrepareForCurrentSettings(request);
  const assetPromise = backgroundAssetPreparePromise;
  if (assetPromise) {
    try {
      await assetPromise;
    } catch {
      // Generation can still build the normal path if eager preparation fails.
    }
  }

  if (foregroundBusy) return true;
  const currentRequest = readRequest();
  if (warmKeyForRequest(currentRequest) !== warmKeyForRequest(request)) {
    scheduleBackgroundStageAndVaePrepareForCurrentSettings(currentRequest, 0);
    return false;
  }

  if (shouldPrepareTransformer || shouldPrepareVae) startStageAndVaePrepareForRequest(currentRequest);
  await waitForStartedPreparePromises();

  if (foregroundBusy) return true;
  const finalPrepareRequest = progressiveFinalPrepareRequestForRequest(currentRequest);
  if (finalPrepareRequest && warmKeyForRequest(readRequest()) === warmKeyForRequest(request)) {
    setStatus([
      "Preparing refinement path",
      `Backend: ${finalPrepareRequest.transformerBackend}`,
      `Speed Profile: ${speedProfileLabel(finalPrepareRequest.speed)}`,
      finalPrepareRequest.previewRenderMaxSize ? `Preview render: ${finalPrepareRequest.previewRenderMaxSize}px max` : "",
      finalPrepareRequest.previewDecodeMaxSize ? `Preview decode: ${finalPrepareRequest.previewDecodeMaxSize}px max` : "",
    ]);
    setLoadPhase("Preparing refinement path");
    startStageAndVaePrepareForRequest(finalPrepareRequest);
    await waitForStartedPreparePromises();
  }
  return true;
}

async function boot() {
  if (!bootStarted) bootStarted = true;
  showRuntimeLoading();
  beginLoadProgress("Downloading assets");
  try {
    installLoadProgressFetch();
    const modelBaseUrl = configuredModelBaseUrl();
    setStatus([
      "Loading browser runtime",
      selectedDownloadInfo().status,
      `Model base: ${modelBaseUrl}`,
    ]);
    setLoadPhase("Loading browser runtime");
    const [{ init }, tokenizer] = await Promise.all([initEngine(), loadTokenizer()]);
    const bootRequest = readRequest();
    const fastPathPrepared = await prepareInitialFastPath(bootRequest);
    showRuntimeReady();
    setStatus([
      "Ready",
      fastPathPrepared ? "Fast path prepared" : "",
      `Model: ${init.config.model_variant || init.config.model_name}`,
      seedInputLine(),
      `Model base: ${configuredModelBaseUrl()}`,
      `Tokenizer: ${tokenizer.constructor?.name || "loaded"}`,
      `Full image backend: ${init.customKernels?.fullImageBackend || "unknown"}`,
    ]);
    if (!fastPathPrepared) {
      startBackgroundAssetPrepareForCurrentSettings(bootRequest);
      scheduleBackgroundStageAndVaePrepareForCurrentSettings(bootRequest);
    }
    if (shouldAutoWarmRequest(bootRequest)) startBackgroundWarmForCurrentSettings();
    finishLoadProgress(fastPathPrepared ? "Fast path prepared" : "Ready");
    return true;
  } catch (err) {
    bootStarted = false;
    bootReady = false;
    resetRuntimeLoadPromises();
    runButton.disabled = true;
    setButtonDisabled(warmButton, true);
    abortButton.disabled = true;
    setStatus([
      err?.stack || err?.message || String(err),
      `Model base: ${configuredModelBaseUrl()}`,
    ], true);
    finishLoadProgress("Load failed", false);
    showDownloadGate({ retry: true, preserveStatus: true });
    return false;
  }
}

startDownloadButton?.addEventListener("click", () => {
  if (bootStarted) return;
  bootStarted = true;
  void boot();
});

warmButton?.addEventListener("click", () => {
  if (!bootReady || foregroundBusy) return;
  clearWarmSchedule();
  foregroundBusy = true;
  warmCurrentSettings().catch((err) => {
    if (isAbortError(err)) return;
    placeholderEl.hidden = false;
    placeholderEl.textContent = "Error";
    setStatus(err?.stack || err?.message || String(err), true);
  }).finally(() => {
    foregroundBusy = false;
    runButton.disabled = false;
    setButtonDisabled(warmButton, false);
    abortButton.disabled = true;
  });
});

runButton.addEventListener("click", () => {
  if (!bootReady || foregroundBusy) return;
  clearWarmSchedule();
  foregroundBusy = true;
  startRunTimer();
  generate().catch((err) => {
    if (isAbortError(err)) {
      placeholderEl.hidden = false;
      placeholderEl.textContent = "Stopped";
      setStatus("Stopped");
      finishRunTimer("Stopped");
      return;
    }
    imageEl.hidden = true;
    canvasEl.hidden = true;
    placeholderEl.hidden = false;
    placeholderEl.textContent = "Error";
    setStatus(err?.stack || err?.message || String(err), true);
    finishRunTimer("Error");
  }).finally(() => {
    foregroundBusy = false;
    runButton.disabled = false;
    setButtonDisabled(warmButton, false);
    abortButton.disabled = true;
    finishRunTimer("Done");
  });
});

abortButton.addEventListener("click", () => {
  clearWarmSchedule();
  backgroundWarmKey = "";
  backgroundWarmResultKey = "";
  backgroundWarmResult = null;
  window.flux2Engine?.abortGeneration?.();
  abortButton.disabled = true;
  if (!runTimerFinalized) updateRunTimer("Stopping");
});

strengthEl.addEventListener("input", () => {
  updateStrengthDisplay();
  scheduleAutoWarmForCurrentSettings();
});

strengthCurveEl.addEventListener("change", () => {
  updateStrengthDisplay();
  scheduleAutoWarmForCurrentSettings();
});

resolutionPresetEl.addEventListener("change", () => {
  applyResolutionPreset(resolutionPresetEl.value);
  scheduleAutoWarmForCurrentSettings();
});

aspectLockButton?.addEventListener("click", () => {
  setAspectLock(!aspectLockEnabled);
  if (aspectLockEnabled) {
    rememberCurrentAspectRatio();
  } else if (aspectRatioEl) {
    aspectRatioEl.value = "free";
  }
});

aspectRatioEl?.addEventListener("change", () => {
  const value = aspectRatioEl.value;
  if (value === "free") {
    setAspectLock(false);
    return;
  }
  setAspectLock(true);
  aspectLockRatio = ASPECT_RATIOS[value] || currentAspectRatio();
  applyAspectToHeight();
  resolutionPresetEl.value = "custom";
  setResolutionAdvancedVisible(true);
  scheduleAutoWarmForCurrentSettings();
});

settingsToggleButton?.addEventListener("click", (event) => {
  event.stopPropagation();
  setSettingsPopoverOpen(settingsPopoverEl?.hidden !== false);
});

settingsPopoverEl?.addEventListener("click", (event) => {
  event.stopPropagation();
});

document.addEventListener("click", () => {
  setSettingsPopoverOpen(false);
});

document.addEventListener("keydown", (event) => {
  if (event.key === "Escape") setSettingsPopoverOpen(false);
});

themeToggleButton.addEventListener("click", () => {
  const currentTheme = document.documentElement.dataset.theme === "light" ? "light" : "dark";
  applyTheme(currentTheme === "dark" ? "light" : "dark");
});

["width", "height"].forEach((id) => {
  const element = $(id);
  element.addEventListener("input", () => {
    if (aspectSyncing) return;
    if (aspectLockEnabled) {
      if (id === "width") applyAspectToHeight();
      else applyAspectToWidth();
    } else {
      $("width").value = String(clampResolutionValue($("width").value));
      $("height").value = String(clampResolutionValue($("height").value));
    }
    syncResolutionPresetFromDimensions({ showAdvancedForCustom: true, preserveCustom: true });
    scheduleAutoWarmForCurrentSettings();
  });
});

initImageInput.addEventListener("change", () => {
  const file = initImageInput.files?.[0];
  if (!file) {
    clearInitImage();
    return;
  }
  if (currentSourceUrl) URL.revokeObjectURL(currentSourceUrl);
  currentSourceUrl = null;
  setInitImageUi(file);
  clearWarmSchedule();
  const request = readRequest();
  startBackgroundAssetPrepareForCurrentSettings(request);
  startStageAndVaePrepareForRequest(request);
  scheduleBackgroundStageAndVaePrepareForCurrentSettings(request, 350);
  currentSourceUrl = URL.createObjectURL(file);
  sourcePreviewEl.src = currentSourceUrl;
  const image = new Image();
  image.onload = () => {
    sourceMetaEl.textContent = `${file.name}\n${image.naturalWidth}x${image.naturalHeight}`;
  };
  image.src = currentSourceUrl;
  sourcePreviewWrap.hidden = false;
});

clearInitImageButton?.addEventListener("click", () => {
  clearWarmSchedule();
  clearInitImage();
});

clearGalleryButton?.addEventListener("click", () => {
  generationHistory = [];
  renderGallery();
});

galleryGridEl?.addEventListener("click", (event) => {
  const button = event.target.closest("button[data-gallery-action]");
  if (!button) return;
  const item = generationHistory.find((entry) => entry.id === button.dataset.galleryId);
  if (!item) return;
  const action = button.dataset.galleryAction;
  if (action === "prompt") {
    applyGalleryPrompt(item);
  } else if (action === "seed") {
    applyGallerySeed(item);
  } else if (action === "reuse") {
    applyGallerySettings(item);
  } else if (action === "img2img") {
    setInitImageFromGallery(item).catch((err) => setStatus(err?.stack || err?.message || String(err), true));
  }
});

[
  "prompt",
  "steps",
  "seed",
  "backend",
  "speed-profile",
  "decode-max",
  "render-max",
  "fit-mode",
].forEach((id) => {
  const element = $(id);
  if (!element) return;
  element.addEventListener(id === "prompt" ? "input" : "change", () => {
    if (id === "backend" && !bootStarted) showDownloadGate();
    scheduleAutoWarmForCurrentSettings(id === "prompt" ? 650 : 350);
  });
});

initTheme();
applyUrlDefaults();
updateStrengthDisplay();
showDownloadGate();