diff --git a/tests/js/test_mega_prompt_v4.mjs b/tests/js/test_mega_prompt_v4.mjs
index 014531c..3f17dfe 100644
--- a/tests/js/test_mega_prompt_v4.mjs
+++ b/tests/js/test_mega_prompt_v4.mjs
@@ -1,6 +1,8 @@
 // Node harness for web/mega_prompt_v4.js (no npm deps): node tests/js/test_mega_prompt_v4.mjs
 import assert from "node:assert/strict";
 import { REELS, ROLL_REELS, readState, shortText, pickLang, historyRows, TEXT } from "../../web/mega_prompt_v4_core.js";
+import { installFakeDom } from "./fake_dom.mjs";
+import { loadExtension } from "./load_extension.mjs";
 
 const tests = [];
 const test = (name, fn) => tests.push([name, fn]);
@@ -33,6 +35,85 @@ test("TEXT has the same keys in both languages", () => {
   assert.equal(REELS.length, 5); assert.deepEqual(ROLL_REELS, ["subject", "location", "style", "effects"]);
 });
 
+// --- the cabinet ----------------------------------------------------------
+const fake = installFakeDom();
+const { app, api } = await loadExtension();
+const ext = app.extensions.find((e) => e.name === "Isulion.MegaPromptV4");
+const nodeType = function () {};
+ext?.beforeRegisterNodeDef(nodeType, { name: "IsulionMegaPromptV4" });
+
+function makeNode() {
+  const node = {
+    widgets: [{ name: "machine_state", value: '{"version": 1}' }],
+    size: [300, 200], properties: {},
+    graph: { changes: 0, change() { this.changes++; } },
+    setSize(s) { this.size = s; }, setDirtyCanvas() {},
+    addDOMWidget(name, type, el, opts) { this.dom = { name, type, el, opts }; return this.dom; },
+  };
+  Object.setPrototypeOf(node, nodeType.prototype);
+  return node;
+}
+const themes = [{ name: "anime", display: "🎌 Anime", icon: "🎌", label: "Anime" }, { name: "cyberpunk", display: "🤖 Cyberpunk", icon: "🤖", label: "Cyberpunk" }];
+const payload = (over = {}) => ({ state: { ...readState(null), theme: { name: "anime", locked: false } }, prompt: "hero, forest", rolled: ["theme", "subject", "location"],
+  segments: [{ reel: "subject", text: "hero" }, { reel: "location", text: "forest" }], seed: 482913, theme: themes[0], ...over });
+const tick = () => new Promise((r) => setImmediate(r));
+async function createNode() {
+  api.responders["/isulion/megaprompt_v4/themes"] = themes;
+  const node = makeNode(); node.onNodeCreated(); fake.flushFrames(); await tick(); await tick();
+  return node;
+}
+const lastRoll = () => api.calls.filter((c) => c.route === "/isulion/megaprompt_v4/roll").at(-1);
+const click = (el) => el.dispatchEvent(new Event("click"));
+
+test("registers extension and builds the cabinet once per node", async () => {
+  assert.ok(ext); const node = await createNode();
+  assert.ok(node._jackpot); assert.equal(node.dom.opts.serialize, false); assert.equal(node.dom.opts.hideOnZoom, false);
+  assert.equal(node.widgets[0].hidden, true); assert.equal(node.widgets[0].type, "converted-widget");
+  await createNode();
+  assert.equal(document.head.children.filter((c) => c.id === "isu-mpv4-styles").length, 1);
+});
+test("lever posts a roll for all reels and applies the result", async () => {
+  const node = await createNode(); api.responders["/isulion/megaprompt_v4/roll"] = payload();
+  click(node._jackpot.ui.lever); await tick(); await tick();
+  assert.deepEqual(lastRoll().body.reels, REELS); fake.runTimers(5000);
+  assert.equal(JSON.parse(node.widgets[0].value).theme.name, "anime");
+  assert.ok(node._jackpot.ui.out.textContent.includes("hero, forest")); assert.ok(node.graph.changes >= 1);
+  assert.equal(node.properties.isu_mpv4.last.seed, 482913);
+});
+test("lock writes the state without rolling", async () => {
+  const node = await createNode(); const before = api.calls.length;
+  click(node._jackpot.ui.reels.subject.btns.lock);
+  assert.equal(JSON.parse(node.widgets[0].value).reels.subject.locked, true); assert.equal(api.calls.length, before);
+});
+test("next theme locks the theme and rerolls the other reels", async () => {
+  const node = await createNode(); api.responders["/isulion/megaprompt_v4/roll"] = payload();
+  node._jackpot.state.theme.name = "anime";
+  click(node._jackpot.ui.reels.theme.btns.next); await tick();
+  const { body } = lastRoll(); assert.deepEqual(body.state.theme, { name: "cyberpunk", locked: true }); assert.deepEqual(body.reels, ROLL_REELS);
+});
+test("onExecuted replays the server result and records history", async () => {
+  const node = await createNode(); node.onExecuted({ draw: [payload({ prompt: "from server", segments: [{ reel: "subject", text: "from server" }] })] });
+  fake.runTimers(5000);
+  assert.equal(node._jackpot.ui.out.textContent.replace(/\s+$/, ""), "from server");
+  assert.equal(node.properties.isu_mpv4.draws, 1); assert.ok(node._jackpot.ui.seed.textContent.includes("482913"));
+});
+test("late roll response is ignored after onExecuted", async () => {
+  const node = await createNode(); let resolve; api.responders["/isulion/megaprompt_v4/roll"] = () => new Promise((r) => (resolve = r));
+  click(node._jackpot.ui.lever); await tick();
+  node.onExecuted({ draw: [payload({ prompt: "server wins", segments: [{ reel: "subject", text: "server wins" }] })] });
+  resolve(payload({ prompt: "late", segments: [{ reel: "subject", text: "late" }] })); await tick(); await tick(); fake.runTimers(5000);
+  assert.equal(node._jackpot.ui.out.textContent.replace(/\s+$/, ""), "server wins");
+});
+test("removing the node twice is safe and leaves nothing running", async () => {
+  const obsBefore = fake.observers.length, docBefore = fake.docListeners();
+  const node = await createNode(); api.responders["/isulion/megaprompt_v4/roll"] = payload();
+  click(node._jackpot.ui.lever); await tick(); await tick();
+  node.onRemoved(); node.dom.onRemove(); node._disposeJackpot();
+  assert.equal(node._jackpot, null); assert.equal(fake.pendingTimers(), 0);
+  assert.equal(fake.docListeners(), docBefore);
+  const mine = fake.observers.slice(obsBefore); assert.ok(mine.length >= 1 && mine.every((o) => o.disconnected));
+});
+
 // --- runner (keep last) ---------------------------------------------------
 let failures = 0;
 for (const [name, fn] of tests) {
diff --git a/web/mega_prompt_v4.js b/web/mega_prompt_v4.js
new file mode 100644
index 0000000..388b7e7
--- /dev/null
+++ b/web/mega_prompt_v4.js
@@ -0,0 +1,702 @@
+import { app } from "../../scripts/app.js";
+import { api } from "../../scripts/api.js";
+import { REELS, ROLL_REELS, readState, shortText, pickLang, historyRows, TEXT } from "./mega_prompt_v4_core.js";
+
+// Mega Prompt V4 « Prompt Jackpot »: an arcade slot machine in a DOM widget.
+// The Python side owns every draw and the prompt assembly; this file edits the
+// hidden machine_state widget, shows what the server returns and animates it.
+
+const NODE_NAME = "IsulionMegaPromptV4";
+const ROUTE = "/isulion/megaprompt_v4";
+const REEL_ICONS = { subject: "👤", location: "🗺️", style: "🎨", effects: "✨" };
+const LANG_KEY = "isu-mpv4-lang";
+
+let themesPromise = null;  // one /themes request shared by every node
+
+function lsGet(key) {
+  try { return localStorage.getItem(key); } catch { return null; }
+}
+function lsSet(key, value) {
+  try { localStorage.setItem(key, value); } catch { /* private mode: language just isn't remembered */ }
+}
+
+function hideWidget(w) {
+  if (!w) return;
+  w.hidden = true;
+  w.type = "converted-widget";
+  w.computeSize = () => [0, -4];
+  if (w.element) w.element.style.display = "none";
+}
+
+function el(tag, cls, text) {
+  const e = document.createElement(tag);
+  if (cls) e.className = cls;
+  if (text != null) e.textContent = text;
+  return e;
+}
+
+const stop = (e) => e.stopPropagation();
+
+const CSS = `
+.isu-mpv4-root{width:100%;height:100%;box-sizing:border-box;font:12px system-ui,sans-serif;color:#e5e7eb}
+.isu-mpv4-cab{position:relative;height:100%;box-sizing:border-box;display:flex;flex-direction:column;gap:7px;padding:9px;border-radius:14px;
+  background:linear-gradient(#24103f,#12081f);border:3px solid #ff2fd0;box-shadow:0 0 18px #ff2fd088,inset 0 0 22px #00e5ff33;animation:isu-mpv4-neon 3s ease-in-out infinite;overflow:hidden}
+@keyframes isu-mpv4-neon{50%{box-shadow:0 0 28px #00e5ffaa,inset 0 0 22px #ff2fd044;border-color:#00e5ff}}
+.isu-mpv4-head{display:flex;align-items:center;justify-content:center;position:relative}
+.isu-mpv4-marquee{font:bold 15px "Courier New",monospace;letter-spacing:.2em;color:#ffe600;text-shadow:0 0 8px #ffe600,0 0 18px #ff2fd0}
+.isu-mpv4-star{animation:isu-mpv4-blink 1.2s infinite}.isu-mpv4-star+.isu-mpv4-star{animation-delay:.6s}
+@keyframes isu-mpv4-blink{50%{opacity:.2}}
+.isu-mpv4-helpbtn{position:absolute;right:0;top:-2px;width:22px;height:22px;border-radius:50%;border:2px solid #00e5ff;background:#020617;color:#00e5ff;
+  font:bold 12px "Courier New",monospace;cursor:pointer;box-shadow:0 0 8px #00e5ff;padding:0}
+.isu-mpv4-top{display:flex;gap:8px}
+.isu-mpv4-crt{flex:1;position:relative;border-radius:12px;background:radial-gradient(ellipse at center,#06122a,#020617 75%);padding:7px;overflow:hidden;
+  border:2px solid #0f2a4a;font-family:"Courier New",monospace}
+.isu-mpv4-crt::after,.isu-mpv4-screen::after{content:"";position:absolute;inset:0;background:repeating-linear-gradient(#0000 0 2px,#0005 2px 3px);pointer-events:none;animation:isu-mpv4-roll 6s linear infinite}
+@keyframes isu-mpv4-roll{to{background-position:0 60px}}
+.isu-mpv4-reels{display:grid;grid-template-columns:1.2fr 1fr 1fr 1fr 1fr;gap:4px}
+.isu-mpv4-reel{position:relative;height:108px;border:2px solid #00e5ff66;border-radius:4px;background:#020617;display:flex;flex-direction:column;
+  align-items:center;justify-content:space-between;padding:3px 2px;overflow:hidden}
+.isu-mpv4-name{font-size:8px;letter-spacing:.08em;color:#00e5ff;text-shadow:0 0 4px #00e5ff}
+.isu-mpv4-face{display:flex;flex-direction:column;align-items:center;text-align:center;min-width:0}
+.isu-mpv4-icon{font-size:24px;line-height:1.15}
+.isu-mpv4-label{font-size:8.5px;color:#cfe9ff;line-height:1.15;max-height:21px;overflow:hidden;word-break:break-word}
+.isu-mpv4-btns{display:flex;gap:2px}
+.isu-mpv4-btn{background:none;border:0;padding:0 2px;font-size:10px;cursor:pointer;border-radius:3px;color:#cfe9ff}
+.isu-mpv4-btn:hover{background:#ffffff22}
+.isu-mpv4-locked{border-color:#ffe600;box-shadow:0 0 9px #ffe600}
+.isu-mpv4-off{opacity:.3;filter:grayscale(1)}
+.isu-mpv4-custom .isu-mpv4-name::after{content:" ✏️"}
+.isu-mpv4-spin .isu-mpv4-face{animation:isu-mpv4-spin .09s linear infinite}
+@keyframes isu-mpv4-spin{0%{transform:translateY(-12px);filter:blur(2px)}100%{transform:translateY(12px);filter:blur(2px)}}
+.isu-mpv4-land .isu-mpv4-face{animation:isu-mpv4-bounce .45s cubic-bezier(.3,1.6,.5,1)}
+@keyframes isu-mpv4-bounce{from{transform:translateY(-16px)}to{transform:none}}
+.isu-mpv4-stick{width:36px;display:flex;flex-direction:column;align-items:center;padding-top:4px;cursor:pointer;background:none;border:0}
+.isu-mpv4-ball{width:30px;height:30px;border-radius:50%;background:radial-gradient(circle at 35% 35%,#ff9af3,#ff2fd0 60%,#7a0a63);box-shadow:0 0 14px #ff2fd0;transition:transform .25s}
+.isu-mpv4-shaft{width:6px;height:74px;background:linear-gradient(90deg,#555,#eee,#555);border-radius:3px;transform-origin:bottom;transition:transform .25s}
+.isu-mpv4-base{width:26px;height:10px;border-radius:4px;background:#444}
+.isu-mpv4-pull .isu-mpv4-shaft{transform:scaleY(.4)}.isu-mpv4-pull .isu-mpv4-ball{transform:translateY(44px)}
+.isu-mpv4-pulltxt{font:bold 8px "Courier New",monospace;color:#ff9af3;margin-top:4px}
+.isu-mpv4-panel{display:flex;gap:6px;align-items:center;font-family:"Courier New",monospace}
+.isu-mpv4-sw{display:flex;border:2px solid #00e5ff66;border-radius:6px;overflow:hidden}
+.isu-mpv4-sw button{background:none;border:0;padding:4px 7px;font:9.5px "Courier New",monospace;color:#7dd3fc;cursor:pointer;letter-spacing:.05em}
+.isu-mpv4-sw button.isu-mpv4-on{background:#00e5ff;color:#020617;box-shadow:0 0 10px #00e5ff;font-weight:bold}
+.isu-mpv4-lora{flex:1;display:flex;align-items:center;gap:5px;border:2px solid #ff2fd066;border-radius:6px;padding:2px 6px;min-width:0}
+.isu-mpv4-lora span{font-size:9px;color:#ff9af3}
+.isu-mpv4-lora input{flex:1;min-width:0;background:transparent;border:0;outline:0;color:#ffd6fa;font:11px "Courier New",monospace}
+.isu-mpv4-screen{position:relative;flex:1;min-height:0;display:flex;flex-direction:column;border-radius:10px;background:#020617;border:2px solid #0f2a4a;padding:8px;font-family:"Courier New",monospace;overflow:hidden}
+.isu-mpv4-hd{display:flex;justify-content:space-between;align-items:center;gap:6px;font-size:9px;color:#ffe600;margin-bottom:4px}
+.isu-mpv4-act{background:none;border:0;color:#ffe600;font:9px "Courier New",monospace;cursor:pointer;padding:0 2px}
+.isu-mpv4-act:hover{text-shadow:0 0 6px #ffe600}
+.isu-mpv4-frozen{color:#7fe7ff;text-shadow:0 0 5px #7fe7ff}
+.isu-mpv4-out{font-size:11.5px;line-height:1.7;min-height:56px;color:#7CFF6B;word-break:break-word}
+.isu-mpv4-seg{padding:1px 3px;border-radius:3px;text-shadow:0 0 5px currentColor;animation:isu-mpv4-pop .4s both}
+.isu-mpv4-seg-subject,.isu-mpv4-seg-location,.isu-mpv4-seg-style,.isu-mpv4-seg-effects{cursor:pointer}
+.isu-mpv4-seg:hover{outline:1px dashed currentColor}
+@keyframes isu-mpv4-pop{from{opacity:0}to{opacity:1}}
+.isu-mpv4-seg-subject{color:#ff8cc0}.isu-mpv4-seg-location{color:#7fe7ff}.isu-mpv4-seg-style{color:#ffd08a}.isu-mpv4-seg-effects{color:#a6f0a8}
+.isu-mpv4-seg-complexity{color:#c4b5fd}.isu-mpv4-seg-lora{color:#e2e8f0;border:1px dashed #64748b}.isu-mpv4-seg-frozen{color:#7fe7ff}.isu-mpv4-seg-error{color:#ff6b6b}
+.isu-mpv4-cursor{display:inline-block;width:7px;height:12px;background:#7CFF6B;vertical-align:middle;animation:isu-mpv4-blink .7s infinite}
+.isu-mpv4-hint{color:#6b7280}
+.isu-mpv4-hist{display:flex;flex-direction:column;gap:3px;margin-top:6px}
+.isu-mpv4-histtitle{font-size:9px;color:#ffe600;letter-spacing:.08em}
+.isu-mpv4-row{display:flex;gap:6px;align-items:baseline;font-size:10.5px;padding:3px 7px;border-radius:6px;background:#1e1036;color:#d8b4fe;border:1px solid #ff2fd033;cursor:pointer}
+.isu-mpv4-row:hover{border-color:#ff2fd0;background:#2a1450}
+.isu-mpv4-no{color:#ff2fd0;flex:0 0 auto}
+.isu-mpv4-tx{flex:1;min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
+.isu-mpv4-st{flex:0 0 auto;color:#6b5a8a;background:none;border:0;cursor:pointer;font-size:11px;padding:0}
+.isu-mpv4-fav{border-color:#ffe60088;color:#fff3a3}.isu-mpv4-fav .isu-mpv4-st{color:#ffe600;text-shadow:0 0 5px #ffe600}
+.isu-mpv4-foot{display:flex;justify-content:space-between;font-size:9px;color:#ffe600;margin-top:auto;padding-top:5px}
+.isu-mpv4-overlay{position:absolute;inset:6px;z-index:5;background:#020617f2;border:2px solid #00e5ff;border-radius:8px;padding:6px;display:flex;flex-direction:column;gap:5px}
+.isu-mpv4-overlay[hidden]{display:none}
+.isu-mpv4-overlay input,.isu-mpv4-overlay textarea{width:100%;box-sizing:border-box;background:#0b1530;border:1px solid #00e5ff66;color:#cfe9ff;font:11px "Courier New",monospace;padding:4px 6px;border-radius:4px;outline:0}
+.isu-mpv4-overlay textarea{flex:1;resize:none;min-height:60px}
+.isu-mpv4-list{display:grid;grid-template-columns:1fr 1fr;gap:2px;overflow:auto;min-height:0}
+.isu-mpv4-list div{font-size:10px;color:#cfe9ff;padding:3px 5px;border-radius:3px;cursor:pointer;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
+.isu-mpv4-list div:hover{background:#00e5ff33}
+.isu-mpv4-editrow{display:flex;gap:4px;justify-content:flex-end}
+.isu-mpv4-editrow button{background:#0b1530;border:1px solid #00e5ff66;color:#00e5ff;font:10px "Courier New",monospace;border-radius:4px;cursor:pointer;padding:3px 8px}
+.isu-mpv4-help{position:absolute;inset:8px;z-index:10;background:#0b0618;border:2px solid #ff2fd0;border-radius:12px;padding:10px 12px;display:flex;flex-direction:column;gap:6px;box-shadow:0 0 24px #ff2fd088}
+.isu-mpv4-help[hidden]{display:none}
+.isu-mpv4-helphd{display:flex;align-items:center;gap:6px;font:bold 13px "Courier New",monospace;color:#ffe600}
+.isu-mpv4-helphd span{flex:1}
+.isu-mpv4-helphd button{background:none;border:1px solid #ff2fd066;color:#ff9af3;border-radius:4px;cursor:pointer;font:10px "Courier New",monospace;padding:2px 6px}
+.isu-mpv4-helphd button.isu-mpv4-on{background:#ff2fd0;color:#fff}
+.isu-mpv4-helpbody{overflow:auto;min-height:0;font:12px/1.45 system-ui,sans-serif;color:#e5e7eb}
+.isu-mpv4-helpbody h4{margin:8px 0 2px;color:#00e5ff;font-size:12px}
+.isu-mpv4-helpbody p{margin:0}
+.isu-mpv4-paused,.isu-mpv4-paused *{animation-play-state:paused!important}
+`;
+
+function injectStyles() {
+  if (document.getElementById("isu-mpv4-styles")) return;
+  const style = el("style", null, CSS);
+  style.id = "isu-mpv4-styles";
+  document.head.appendChild(style);
+}
+
+class PromptJackpot {
+  constructor(node, dataWidget, root) {
+    Object.assign(this, { node, dataWidget, root, reqId: 0, timers: new Set(), typing: null, disposed: false, visible: true, themes: [] });
+    this.lang = pickLang(navigator.language, lsGet(LANG_KEY));
+    this.knownThemes = new Map();  // theme entries seen in roll results, before /themes answers
+    this.docCleanups = [];
+    injectStyles();
+    this.build();
+
+    this.onVisibility = () => this.updatePaused();
+    document.addEventListener("visibilitychange", this.onVisibility);
+    this.intersection = new IntersectionObserver(([e]) => { this.visible = !!e?.isIntersecting; this.updatePaused(); });
+    this.intersection.observe(root);
+    this.onWheel = (e) => app.canvas?.canvas?.dispatchEvent(new WheelEvent(e.type, e));  // keep graph zoom working
+    root.addEventListener("pointerdown", stop);
+    root.addEventListener("wheel", this.onWheel, { passive: true });
+
+    this.load();
+    this.loadThemes();
+  }
+
+  get t() { return TEXT[this.lang]; }
+
+  // --- DOM ----------------------------------------------------------------
+  build() {
+    const ui = (this.ui = {});
+    this.root.className = "isu-mpv4-root";
+    const cab = el("div", "isu-mpv4-cab");
+    this.root.appendChild(cab);
+
+    const head = el("div", "isu-mpv4-head");
+    ui.marquee = el("span", "isu-mpv4-marquee");
+    ui.helpBtn = el("button", "isu-mpv4-helpbtn", "?");
+    ui.helpBtn.addEventListener("click", () => this.toggleHelp());
+    head.append(el("span", "isu-mpv4-marquee isu-mpv4-star", "★ "), ui.marquee, el("span", "isu-mpv4-marquee isu-mpv4-star", " ★"), ui.helpBtn);
+
+    const top = el("div", "isu-mpv4-top");
+    ui.crt = el("div", "isu-mpv4-crt");
+    const grid = el("div", "isu-mpv4-reels");
+    ui.reels = {};
+    for (const name of REELS) grid.appendChild(this.buildReel(name));
+    ui.crt.append(grid, this.buildSearch(), this.buildEditor());
+    ui.lever = el("button", "isu-mpv4-stick");
+    ui.pullText = el("span", "isu-mpv4-pulltxt");
+    ui.lever.append(el("span", "isu-mpv4-ball"), el("span", "isu-mpv4-shaft"), el("span", "isu-mpv4-base"), ui.pullText);
+    ui.lever.addEventListener("click", () => this.pullLever());
+    top.append(ui.crt, ui.lever);
+
+    const panel = el("div", "isu-mpv4-panel");
+    const sw = el("div", "isu-mpv4-sw");
+    ui.cx = {};
+    for (const v of ["simple", "detailed", "complex"]) {
+      const b = (ui.cx[v] = el("button"));
+      b.addEventListener("click", () => this.setComplexity(v));
+      sw.appendChild(b);
+    }
+    const lora = el("label", "isu-mpv4-lora");
+    ui.loraLabel = el("span");
+    ui.lora = el("input");
+    ui.lora.addEventListener("keydown", (e) => { e.stopPropagation(); if (e.key === "Enter") ui.lora.blur(); });
+    ui.lora.addEventListener("change", () => this.setLora(ui.lora.value));
+    lora.append(ui.loraLabel, ui.lora);
+    panel.append(sw, lora);
+
+    const screen = el("div", "isu-mpv4-screen");
+    const hd = el("div", "isu-mpv4-hd");
+    ui.promptTitle = el("span");
+    ui.frozenBadge = el("span", "isu-mpv4-frozen");
+    ui.frozenBadge.hidden = true;
+    const acts = el("span");
+    ui.copyBtn = el("button", "isu-mpv4-act");
+    ui.copyBtn.addEventListener("click", () => this.copyPrompt());
+    ui.editBtn = el("button", "isu-mpv4-act");
+    ui.editBtn.addEventListener("click", () => this.openPromptEditor());
+    acts.append(ui.copyBtn, ui.editBtn);
+    hd.append(ui.promptTitle, ui.frozenBadge, acts);
+    ui.out = el("div", "isu-mpv4-out");
+    ui.hist = el("div", "isu-mpv4-hist");
+    ui.hist.rows = [];
+    const foot = el("div", "isu-mpv4-foot");
+    ui.draws = el("span");
+    ui.seed = el("span");
+    foot.append(ui.draws, ui.seed);
+    screen.append(hd, ui.out, ui.hist, foot);
+
+    cab.append(head, top, panel, screen, this.buildHelp());
+  }
+
+  buildReel(name) {
+    const box = el("div", "isu-mpv4-reel");
+    const nameEl = el("div", "isu-mpv4-name");
+    const face = el("div", "isu-mpv4-face");
+    const icon = el("span", "isu-mpv4-icon");
+    const label = el("span", "isu-mpv4-label");
+    face.append(icon, label);
+    const btnBox = el("div", "isu-mpv4-btns");
+    const btns = {};
+    const add = (key, action) => {
+      const b = (btns[key] = el("button", "isu-mpv4-btn"));
+      b.addEventListener("click", action);
+      btnBox.appendChild(b);
+    };
+    if (name === "theme") add("prev", () => this.stepTheme(-1));
+    add("lock", () => this.toggleLock(name));
+    if (name === "theme") {
+      add("search", () => this.openSearch());
+      add("next", () => this.stepTheme(1));
+    }
+    if (name === "subject" || name === "location") add("edit", () => this.openInlineEdit(name));
+    if (name !== "theme" && name !== "subject") add("toggle", () => this.toggleEnabled(name));
+    box.append(nameEl, face, btnBox);
+    this.ui.reels[name] = { box, name: nameEl, face, icon, label, btns };
+    return box;
+  }
+
+  buildSearch() {
+    const panel = el("div", "isu-mpv4-overlay");
+    panel.hidden = true;
+    const input = el("input");
+    const list = el("div", "isu-mpv4-list");
+    list.addEventListener("wheel", stop, { passive: true });
+    input.addEventListener("input", () => this.renderSearch(input.value));
+    input.addEventListener("keydown", (e) => {
+      e.stopPropagation();
+      if (e.key === "Escape") this.closeSearch();
+      if (e.key === "Enter") { const first = this.filterThemes(input.value)[0]; if (first) this.setTheme(first.name); }
+    });
+    panel.append(input, list);
+    this.ui.search = { panel, input, list };
+    return panel;
+  }
+
+  buildEditor() {
+    const panel = el("div", "isu-mpv4-overlay");
+    panel.hidden = true;
+    const input = el("input");
+    const textarea = el("textarea");
+    textarea.addEventListener("wheel", stop, { passive: true });
+    const row = el("div", "isu-mpv4-editrow");
+    const clear = el("button", null, "✕");
+    const cancel = el("button");
+    const ok = el("button");
+    row.append(clear, cancel, ok);
+    panel.append(input, textarea, row);
+    this.ui.editor = { panel, input, textarea, clear, cancel, ok };
+    return panel;
+  }
+
+  buildHelp() {
+    const panel = el("div", "isu-mpv4-help");
+    panel.hidden = true;
+    const hd = el("div", "isu-mpv4-helphd");
+    const title = el("span");
+    const langFr = el("button", null, "FR");
+    const langEn = el("button", null, "EN");
+    const close = el("button");
+    langFr.addEventListener("click", () => this.setLang("fr"));
+    langEn.addEventListener("click", () => this.setLang("en"));
+    close.addEventListener("click", () => this.closeHelp());
+    hd.append(title, langFr, langEn, close);
+    const body = el("div", "isu-mpv4-helpbody");
+    body.addEventListener("wheel", stop, { passive: true });
+    panel.append(hd, body);
+    this.ui.help = { panel, title, langFr, langEn, close, body };
+    return panel;
+  }
+
+  // --- state ----------------------------------------------------------------
+  load() {
+    this.state = readState(this.dataWidget.value);
+    this.view = this.node.properties.isu_mpv4 ??= { draws: 0, seed: null, history: [], last: null };
+    if (this.view.last?.theme) this.knownThemes.set(this.view.last.theme.name, this.view.last.theme);
+    this.render();
+  }
+
+  commit() {
+    const v = JSON.stringify(this.state);
+    if (v === this.dataWidget.value) return;
+    this.dataWidget.value = v;
+    this.dataWidget.callback?.(v);
+    this.node.graph?.change();
+    this.node.setDirtyCanvas(true, true);
+  }
+
+  saveView() {
+    this.node.properties.isu_mpv4 = this.view;
+  }
+
+  loadThemes() {
+    themesPromise ??= api.fetchApi(`${ROUTE}/themes`)
+      .then((r) => { if (!r.ok) throw new Error(`HTTP ${r.status}`); return r.json(); })
+      .catch((err) => { themesPromise = null; throw err; });
+    themesPromise
+      .then((list) => { if (this.disposed || !Array.isArray(list)) return; this.themes = list; this.renderReel("theme"); })
+      .catch((err) => console.warn("[Isulion] Mega Prompt V4: theme list unavailable", err));
+  }
+
+  themeInfo() {
+    const name = this.state.theme.name;
+    return this.themes.find((t) => t.name === name) ?? this.knownThemes.get(name) ?? { name, icon: "🎰", label: name || "?" };
+  }
+
+  // --- server ---------------------------------------------------------------
+  async roll(reels) {
+    const id = ++this.reqId;
+    let r, payload;
+    try {
+      r = await api.fetchApi(`${ROUTE}/roll`, {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ state: this.state, reels }),
+      });
+      payload = await r.json();
+    } catch (err) {
+      if (id === this.reqId && !this.disposed) this.showError(String(err?.message ?? err));
+      return;
+    }
+    if (id !== this.reqId || this.disposed) return;  // a newer roll or an execution result won
+    if (!r.ok) return this.showError(payload?.error ?? `HTTP ${r.status}`);
+    const changed = payload.rolled?.length > 0;
+    this.applyResult(payload, { animate: changed, record: changed });
+  }
+
+  applyResult(payload, { animate, record }) {
+    this.state = readState(payload.state);
+    this.commit();
+    if (payload.theme?.name) this.knownThemes.set(payload.theme.name, payload.theme);
+    this.view.last = payload;
+    this.view.seed = payload.seed ?? null;
+    if (record) {
+      this.view.draws += 1;
+      this.pushHistory(payload);
+    }
+    this.saveView();
+    this.renderFooter();
+    const segments = payload.segments ?? [];
+    if (animate) {
+      this.spinReels(payload.rolled ?? [], () => { this.renderReels(); this.typePrompt(segments); });
+    } else {
+      this.renderReels();
+      this.renderPrompt(segments);
+    }
+  }
+
+  onExecuted(payload) {
+    if (!payload) return;
+    this.reqId++;  // any roll still in flight is now stale
+    this.applyResult(payload, { animate: true, record: true });
+  }
+
+  showError(message) {
+    for (const name of REELS) this.ui.reels[name].box.classList.remove("isu-mpv4-spin");
+    this.renderPrompt([{ reel: "error", text: `${this.t.error}: ${message}` }]);
+  }
+
+  // --- actions --------------------------------------------------------------
+  pullLever() {
+    if (this.state.frozen_prompt) this.state.frozen_prompt = "";
+    this.pullAnimation();
+    for (const name of this.freeReels()) this.ui.reels[name].box.classList.add("isu-mpv4-spin");
+    this.roll(REELS);
+  }
+
+  freeReels() {
+    return REELS.filter((name) => (name === "theme"
+      ? !this.state.theme.locked
+      : !this.state.reels[name].locked && this.state.reels[name].enabled !== false));
+  }
+
+  toggleLock(name) {
+    const target = name === "theme" ? this.state.theme : this.state.reels[name];
+    target.locked = !target.locked;
+    this.commit();
+    this.renderReel(name);
+  }
+
+  toggleEnabled(name) {
+    const reel = this.state.reels[name];
+    reel.enabled = !reel.enabled;
+    this.commit();
+    this.renderReel(name);
+    this.roll([]);
+  }
+
+  stepTheme(dir) {
+    const list = this.themes;
+    if (!list.length) return;
+    const i = list.findIndex((t) => t.name === this.state.theme.name);
+    const j = i < 0 ? 0 : (i + dir + list.length) % list.length;
+    this.setTheme(list[j].name);
+  }
+
+  setTheme(name) {
+    this.state.theme = { name, locked: true };
+    this.commit();
+    this.closeSearch();
+    this.renderReel("theme");
+    for (const r of ROLL_REELS) if (this.freeReels().includes(r)) this.ui.reels[r].box.classList.add("isu-mpv4-spin");
+    this.roll(ROLL_REELS);
+  }
+
+  setComplexity(v) {
+    this.state.complexity = v;
+    this.commit();
+    this.renderComplexity();
+    this.roll([]);
+  }
+
+  setLora(v) {
+    this.state.lora = v;
+    this.commit();
+    this.roll([]);
+  }
+
+  copyPrompt() {
+    navigator.clipboard?.writeText(this.view.last?.prompt ?? "")?.catch?.(() => {});
+    this.ui.copyBtn.textContent = this.t.copied;
+    this.setTimer(() => { this.ui.copyBtn.textContent = this.t.copy; }, 1200);
+  }
+
+  // search panel
+  filterThemes(q) {
+    const needle = String(q).trim().toLowerCase();
+    return this.themes.filter((t) => t.label.toLowerCase().includes(needle));
+  }
+
+  openSearch() {
+    const { panel, input } = this.ui.search;
+    panel.hidden = false;
+    input.value = "";
+    this.renderSearch("");
+    input.focus();
+  }
+
+  closeSearch() {
+    this.ui.search.panel.hidden = true;
+  }
+
+  renderSearch(q) {
+    const rows = this.filterThemes(q).map((t) => {
+      const row = el("div", null, `${t.icon} ${t.label}`);
+      row.addEventListener("click", () => this.setTheme(t.name));
+      return row;
+    });
+    this.ui.search.list.replaceChildren(...rows);
+  }
+
+  // inline editors (Tâche 9)
+  openInlineEdit() {}
+  openPromptEditor() {}
+
+  // history (Tâche 10)
+  pushHistory() {}
+  renderHistory() {}
+
+  // help (Tâche 11)
+  toggleHelp() {}
+  closeHelp() {}
+  setLang() {}
+
+  // --- rendering ------------------------------------------------------------
+  render() {
+    this.renderLabels();
+    this.renderReels();
+    this.renderComplexity();
+    this.ui.lora.value = this.state.lora;
+    this.renderFooter();
+    this.renderHistory();
+    if (this.view.last) this.renderPrompt(this.view.last.segments ?? []);
+    else this.renderPrompt([]);
+  }
+
+  renderLabels() {
+    const t = this.t, ui = this.ui;
+    ui.marquee.textContent = t.marquee;
+    for (const name of REELS) ui.reels[name].name.textContent = t.reels[name];
+    ui.pullText.textContent = t.pull;
+    for (const [v, b] of Object.entries(ui.cx)) b.textContent = t.complexity[v];
+    ui.loraLabel.textContent = t.lora;
+    ui.promptTitle.textContent = t.promptTitle;
+    ui.copyBtn.textContent = t.copy;
+    ui.editBtn.textContent = t.edit;
+    ui.frozenBadge.textContent = t.frozenBadge;
+    ui.search.input.placeholder = t.searchPlaceholder;
+    ui.editor.input.placeholder = t.editPlaceholder;
+    ui.editor.cancel.textContent = t.cancel;
+    ui.editor.ok.textContent = t.ok;
+  }
+
+  renderReels() {
+    for (const name of REELS) this.renderReel(name);
+  }
+
+  renderReel(name) {
+    const r = this.ui.reels[name];
+    let icon, label, locked, off = false, custom = false;
+    if (name === "theme") {
+      const info = this.themeInfo();
+      icon = info.icon;
+      label = info.label;
+      locked = this.state.theme.locked;
+    } else {
+      const reel = this.state.reels[name];
+      custom = !!reel.custom;
+      icon = custom ? "✏️" : REEL_ICONS[name];
+      label = shortText(reel.text || reel.custom);
+      locked = reel.locked;
+      off = reel.enabled === false;
+      if (r.btns.toggle) r.btns.toggle.textContent = off ? "🚫" : "👁";
+    }
+    r.icon.textContent = icon;
+    r.label.textContent = label;
+    r.btns.lock.textContent = locked ? "🔒" : "🔓";
+    if (r.btns.prev) { r.btns.prev.textContent = "◀"; r.btns.next.textContent = "▶"; r.btns.search.textContent = "🔍"; }
+    if (r.btns.edit) r.btns.edit.textContent = "✏️";
+    r.box.classList.toggle("isu-mpv4-locked", locked);
+    r.box.classList.toggle("isu-mpv4-off", off);
+    r.box.classList.toggle("isu-mpv4-custom", custom);
+  }
+
+  renderComplexity() {
+    for (const [v, b] of Object.entries(this.ui.cx)) b.classList.toggle("isu-mpv4-on", v === this.state.complexity);
+  }
+
+  renderFooter() {
+    this.ui.draws.textContent = this.t.draw + String(this.view.draws).padStart(3, "0");
+    this.ui.seed.textContent = this.t.seed + (this.view.seed ?? "—");
+  }
+
+  cursor() {
+    return el("span", "isu-mpv4-cursor");
+  }
+
+  renderPrompt(segments) {
+    clearInterval(this.typing);
+    this.typing = null;
+    const out = this.ui.out;
+    out.replaceChildren();
+    if (!segments.length) out.appendChild(el("span", "isu-mpv4-hint", this.t.emptyHint));
+    segments.forEach((seg, i) => {
+      if (i) out.append(", ");
+      const span = el("span", `isu-mpv4-seg isu-mpv4-seg-${seg.reel}`, seg.text);
+      if (ROLL_REELS.includes(seg.reel)) span.addEventListener("click", () => this.roll([seg.reel]));
+      out.appendChild(span);
+    });
+    out.appendChild(this.cursor());
+    this.ui.frozenBadge.hidden = !this.state.frozen_prompt.trim();
+  }
+
+  typePrompt(segments) {
+    clearInterval(this.typing);
+    const full = segments.map((s) => s.text).join(", ");
+    if (!full) return this.renderPrompt(segments);
+    let k = 0;
+    this.typing = setInterval(() => {
+      k += 3;
+      this.ui.out.textContent = full.slice(0, k);
+      this.ui.out.appendChild(this.cursor());
+      if (k >= full.length) this.renderPrompt(segments);
+    }, 14);
+  }
+
+  // --- animation ------------------------------------------------------------
+  setTimer(fn, ms) {
+    const id = setTimeout(() => { this.timers.delete(id); if (!this.disposed) fn(); }, ms);
+    this.timers.add(id);
+  }
+
+  pullAnimation() {
+    this.ui.lever.classList.add("isu-mpv4-pull");
+    this.setTimer(() => this.ui.lever.classList.remove("isu-mpv4-pull"), 320);
+  }
+
+  spinReels(names, done) {
+    if (!names.length) return done();
+    this.pullAnimation();
+    names.forEach((name, i) => {
+      const box = this.ui.reels[name].box;
+      box.classList.remove("isu-mpv4-land");
+      box.classList.add("isu-mpv4-spin");
+      this.setTimer(() => {
+        box.classList.remove("isu-mpv4-spin");
+        box.classList.add("isu-mpv4-land");
+        this.renderReel(name);
+        if (i === names.length - 1) done();
+      }, 450 + 280 * i);
+    });
+  }
+
+  updatePaused() {
+    this.root.classList.toggle("isu-mpv4-paused", !this.visible || document.hidden);
+  }
+
+  dispose() {
+    if (this.disposed) return;
+    this.disposed = true;
+    this.reqId++;
+    for (const id of this.timers) clearTimeout(id);
+    this.timers.clear();
+    clearInterval(this.typing);
+    this.typing = null;
+    this.intersection.disconnect();
+    document.removeEventListener("visibilitychange", this.onVisibility);
+    for (const fn of this.docCleanups.splice(0)) fn();
+    this.root.removeEventListener("pointerdown", stop);
+    this.root.removeEventListener("wheel", this.onWheel);
+    this.root.replaceChildren();
+  }
+}
+
+app.registerExtension({
+  name: "Isulion.MegaPromptV4",
+  beforeRegisterNodeDef(nodeType, nodeData) {
+    if (nodeData.name !== NODE_NAME) return;
+
+    const onNodeCreated = nodeType.prototype.onNodeCreated;
+    nodeType.prototype.onNodeCreated = function () {
+      const r = onNodeCreated?.apply(this, arguments);
+      const data = this.widgets?.find((w) => w.name === "machine_state");
+      hideWidget(data);
+      const root = document.createElement("div");
+      const dom = this.addDOMWidget("prompt_jackpot", "isulion-prompt-jackpot", root, {
+        getMinHeight: () => 560, hideOnZoom: false, serialize: false,
+      });
+      this.setSize([Math.max(this.size[0], 480), Math.max(this.size[1], 640)]);
+      // root has no size before the first frame; cancel if the node is removed meanwhile
+      this._jackpotRaf = requestAnimationFrame(() => {
+        this._jackpotRaf = null;
+        if (!data) return;
+        try { this._jackpot = new PromptJackpot(this, data, root); }
+        catch (err) { console.error("[Isulion] Mega Prompt V4 failed to start", err); }
+      });
+      dom.onRemove = () => this._disposeJackpot();
+      return r;
+    };
+
+    const onConfigure = nodeType.prototype.onConfigure;
+    nodeType.prototype.onConfigure = function () {
+      const r = onConfigure?.apply(this, arguments);
+      this._jackpot?.load();  // widgets_values and properties were just restored
+      return r;
+    };
+
+    const onExecuted = nodeType.prototype.onExecuted;
+    nodeType.prototype.onExecuted = function (message) {
+      const r = onExecuted?.apply(this, arguments);
+      this._jackpot?.onExecuted(message?.draw?.[0]);  // message is the "ui" dict, values are lists
+      return r;
+    };
+
+    const onRemoved = nodeType.prototype.onRemoved;
+    nodeType.prototype.onRemoved = function () {
+      const r = onRemoved?.apply(this, arguments);
+      this._disposeJackpot();
+      return r;
+    };
+
+    // called by both onRemoved and the DOM widget's onRemove; safe to run twice
+    nodeType.prototype._disposeJackpot = function () {
+      if (this._jackpotRaf != null) cancelAnimationFrame(this._jackpotRaf);
+      this._jackpotRaf = null;
+      this._jackpot?.dispose();
+      this._jackpot = null;
+    };
+  },
+});