// Phase 1.2 — Заменяет IV-6 stubs в §3, §6, §8 на полноценные интерактивы:
//   §3 Heat Conductor Bench — drag-стержни разных материалов
//   §6 Heat Mixer            — drag двух ёмкостей с T1, T2 → T_итог
//   §8 Phase Diagram T(t)    — анимированный график плавления льда
'use strict';
const fs = require('fs');
const path = require('path');

const DST = path.join(__dirname, '..', '..', 'frontend', 'textbooks', 'physics_8_ch1.html');
let h = fs.readFileSync(DST, 'utf8');

// === Замена stub'а для одного § на реальный виджет + init ===
function replaceStub(pid, widgetHtml, initFn) {
  const stubMatch = h.match(new RegExp(
    `\\/\\* IV6 — flagship интерактив[^\\n]*\\)[^\\n]*\\*\\/[\\s\\S]*?\\+'</div>';\\s*\\n\\s*box\\.innerHTML = h \\+ secNavFor\\('${pid}'\\)`
  ));
  if (!stubMatch) { console.warn(`${pid}: stub not found`); return false; }
  const stubText = stubMatch[0];
  // Replace stub HTML portion (everything before the box.innerHTML line)
  const lastBox = stubText.lastIndexOf("box.innerHTML");
  const stubHtmlPart = stubText.slice(0, lastBox).trimEnd();
  const newStubHtml = widgetHtml.trim() + '\n\n  ';
  h = h.replace(stubHtmlPart, newStubHtml);
  // Add init call after wireReadBtn
  h = h.replace(`wireReadBtn('${pid}');`, `wireReadBtn('${pid}');\n  _init${pid.toUpperCase()}_iv6();`);
  // Append init function after build_pN
  const fnStart = h.indexOf(`function build_${pid}()`);
  const fnEnd = h.indexOf('\n}\n', fnStart);
  h = h.slice(0, fnEnd + 3) + '\n' + initFn.trim() + '\n' + h.slice(fnEnd + 3);
  console.log(`${pid}: replaced stub with real IV-6`);
  return true;
}

// =====================================================================
// §3 — Heat Conductor Bench
// =====================================================================
const P3_HTML = `
  /* IV6 — Heat Conductor Bench (Phase 1.2) */
  h += '<div class="wg p8-iv6">'
    +'<div class="wg-header"><span class="wg-badge p8-badge p8-badge-thermal">IV-6</span><div class="wg-title">Тепловая лавочка — какой материал быстрее проводит тепло?</div></div>'
    +'<div class="wg-help">Перетащи один из стержней (медь, дерево, стекло, серебро) на горелку. Цветовая карта покажет, как тепло движется по стержню. Чем больше λ — тем быстрее.</div>'
    +'<div class="p8-sandbox" id="p3-iv6-sandbox" style="height:300px"></div>'
    +'<div style="margin-top:10px;display:flex;gap:10px;flex-wrap:wrap">'
      +'<div class="p8-readout"><span class="p8-readout-label">Материал</span><span class="p8-readout-value" id="p3-iv6-mat">—</span></div>'
      +'<div class="p8-readout"><span class="p8-readout-label">λ</span><span class="p8-readout-value" id="p3-iv6-lam">—</span><span class="p8-readout-unit">Вт/(м·К)</span></div>'
      +'<div class="p8-readout"><span class="p8-readout-label">T дальнего конца</span><span class="p8-readout-value" id="p3-iv6-tend">—</span><span class="p8-readout-unit">°C</span></div>'
    +'</div>'
    +'</div>';
`;

const P3_INIT = `
function _initP3_iv6(){
  const sb = document.getElementById('p3-iv6-sandbox');
  if (!sb || !window.P8Helpers || !window.P8Drag || !window.P8Anim) return;
  const svg = P8Helpers.svg.create(560, 300);
  svg.setAttribute('width','100%'); svg.setAttribute('height','100%'); svg.style.display='block';
  sb.appendChild(svg);
  /* Горелка (drop zone) */
  const burner = P8Helpers.svg.el('g', { transform: 'translate(80, 240)' });
  burner.appendChild(P8Helpers.svg.el('rect', { x:-32, y:-8, width:64, height:32, rx:4, fill:'#475569' }));
  burner.appendChild(P8Helpers.svg.el('rect', { x:-26, y:-22, width:52, height:14, rx:7, fill:'#dc2626' }));
  burner.appendChild(P8Helpers.svg.el('text', { x:0, y:48, 'font-family':"'Inter',sans-serif", 'font-size':11, 'font-weight':700, fill:'#475569', 'text-anchor':'middle', text:'Горелка (drop)' }));
  svg.appendChild(burner);
  /* Палитра 4 стержней */
  const rods = [
    { name:'Медь',     lam:400, color:'#b45309', x:200, y:50 },
    { name:'Серебро',  lam:430, color:'#9ca3af', x:300, y:50 },
    { name:'Стекло',   lam:0.8, color:'#bae6fd', x:400, y:50 },
    { name:'Дерево',   lam:0.15,color:'#a16207', x:500, y:50 }
  ];
  const rodEls = [];
  rods.forEach((rod, i) => {
    const g = P8Helpers.svg.el('g', { transform: 'translate('+rod.x+','+rod.y+')' });
    /* Sections of rod, each will be colored by T gradient when active */
    const segments = 12;
    const segs = [];
    for (let s = 0; s < segments; s++) {
      const r = P8Helpers.svg.el('rect', {
        x: -55 + s * (110/segments), y: -10, width: 110/segments, height: 20,
        fill: rod.color, stroke: 'none'
      });
      g.appendChild(r);
      segs.push(r);
    }
    /* Frame */
    g.appendChild(P8Helpers.svg.el('rect', { x:-55, y:-10, width:110, height:20, rx:3, fill:'none', stroke:'#0f172a', 'stroke-width':1.5 }));
    g.appendChild(P8Helpers.svg.el('text', { x:0, y:-18, 'font-family':"'Inter',sans-serif", 'font-size':11, 'font-weight':700, fill:'#0f172a', 'text-anchor':'middle', text: rod.name }));
    g.appendChild(P8Helpers.svg.el('text', { x:0, y:30, 'font-family':"'JetBrains Mono',monospace", 'font-size':9, 'font-weight':600, fill:'var(--p8-muted, #64748b)', 'text-anchor':'middle', text: 'λ='+rod.lam }));
    svg.appendChild(g);
    rodEls.push({ rod, g, segs, x: rod.x, y: rod.y });
  });
  /* Active sim state */
  let activeIdx = -1;
  let simLoop = null;
  let simTime = 0;
  const matEl = document.getElementById('p3-iv6-mat');
  const lamEl = document.getElementById('p3-iv6-lam');
  const tendEl = document.getElementById('p3-iv6-tend');
  function resetColors(rodObj){
    rodObj.segs.forEach(s => s.setAttribute('fill', rodObj.rod.color));
  }
  function startSim(rodObj){
    if (simLoop) simLoop.stop();
    simTime = 0;
    /* λ нормализованный 0..1: log scale (15 -> 430) */
    const lamNorm = Math.min(1, Math.log10(rodObj.rod.lam + 1) / Math.log10(500));
    simLoop = P8Anim.raf((dt, t) => {
      simTime += dt;
      /* Diffusion-like: каждый сегмент i прогревается со скоростью lamNorm */
      const speed = lamNorm * 0.8 + 0.04;
      rodObj.segs.forEach((seg, i) => {
        const pos = i / (rodObj.segs.length - 1);
        const wave = speed * simTime;
        const heat = Math.max(0, Math.min(1, wave - pos));
        seg.setAttribute('fill', P8Helpers.thermal.tempColor(heat * 0.85 + 0.1));
      });
      /* T-end value */
      const endHeat = Math.max(0, Math.min(1, speed * simTime - 0.95));
      const tEnd = Math.round(20 + endHeat * 80);
      if (tendEl) tendEl.textContent = tEnd;
      if (simTime > 30) simLoop.stop();
    });
    simLoop.start();
    if (matEl) matEl.textContent = rodObj.rod.name;
    if (lamEl) lamEl.textContent = rodObj.rod.lam;
  }
  /* Attach drag to each rod */
  rodEls.forEach((rodObj, i) => {
    P8Drag.attach(rodObj.g, {
      container: svg,
      onMove: (ev, pos) => {
        rodObj.x = pos.x;
        rodObj.y = pos.y;
        rodObj.g.setAttribute('transform', 'translate('+rodObj.x+','+rodObj.y+')');
      },
      onEnd: (ev, pos) => {
        /* Check if dropped near burner */
        if (Math.abs(pos.x - 80) < 70 && Math.abs(pos.y - 240) < 50) {
          /* Snap to position above burner */
          P8Anim.tween({
            from: 0, to: 1, duration: 320, easing: 'cubicOut',
            onUpdate: k => {
              rodObj.x = pos.x + (80 + 55 - pos.x) * k;
              rodObj.y = pos.y + (220 - pos.y) * k;
              rodObj.g.setAttribute('transform', 'translate('+rodObj.x+','+rodObj.y+')');
            }
          });
          /* Reset other rods to original */
          rodEls.forEach((other, j) => {
            if (j === i) return;
            resetColors(other);
          });
          activeIdx = i;
          startSim(rodObj);
          if (window.addXp) addXp(10, 'p3-iv6-conduct');
        }
      }
    });
  });
  /* Help text */
  svg.appendChild(P8Helpers.svg.el('text', {
    x: 280, y: 290,
    'font-family': "'Inter', sans-serif", 'font-size': 10,
    fill: 'var(--p8-muted, #64748b)', 'text-anchor': 'middle',
    text: 'Перетащи стержень на горелку • Чем выше λ — тем быстрее цвет дойдёт до конца'
  }));
}
`;
replaceStub('p3', P3_HTML, P3_INIT);

// =====================================================================
// §6 — Heat Mixer (Q = cmΔT)
// =====================================================================
const P6_HTML = `
  /* IV6 — Heat Mixer (Phase 1.2) */
  h += '<div class="wg p8-iv6">'
    +'<div class="wg-header"><span class="wg-badge p8-badge p8-badge-thermal">IV-6</span><div class="wg-title">Смесь двух жидкостей — рассчитай конечную T</div></div>'
    +'<div class="wg-help">Перетащи ёмкости друг к другу — они смешаются. Масса и начальная температура каждой — на скрубберах ниже. Конечная температура считается по уравнению теплового баланса $c m_1 (T_1 - T) = c m_2 (T - T_2)$.</div>'
    +'<div class="p8-sandbox" id="p6-iv6-sandbox" style="height:240px"></div>'
    +'<div style="margin-top:12px;display:grid;grid-template-columns:1fr 1fr;gap:10px">'
      +'<div class="p8-scrubber"><span class="p8-scrubber-label">m₁</span><input type="range" id="p6-iv6-m1" min="0.1" max="2" step="0.1" value="0.5"><span class="p8-scrubber-value"><span id="p6-iv6-m1-val">0.5</span><span class="p8-unit">кг</span></span></div>'
      +'<div class="p8-scrubber"><span class="p8-scrubber-label">T₁</span><input type="range" id="p6-iv6-t1" min="0" max="100" step="1" value="80"><span class="p8-scrubber-value"><span id="p6-iv6-t1-val">80</span><span class="p8-unit">°C</span></span></div>'
      +'<div class="p8-scrubber"><span class="p8-scrubber-label">m₂</span><input type="range" id="p6-iv6-m2" min="0.1" max="2" step="0.1" value="1"><span class="p8-scrubber-value"><span id="p6-iv6-m2-val">1.0</span><span class="p8-unit">кг</span></span></div>'
      +'<div class="p8-scrubber"><span class="p8-scrubber-label">T₂</span><input type="range" id="p6-iv6-t2" min="0" max="100" step="1" value="20"><span class="p8-scrubber-value"><span id="p6-iv6-t2-val">20</span><span class="p8-unit">°C</span></span></div>'
    +'</div>'
    +'<div style="margin-top:10px;display:flex;gap:10px;flex-wrap:wrap">'
      +'<div class="p8-readout"><span class="p8-readout-label">T_итог</span><span class="p8-readout-value" id="p6-iv6-tf">—</span><span class="p8-readout-unit">°C</span></div>'
      +'<button class="btn primary" id="p6-iv6-mix">Смешать</button>'
      +'<button class="btn" id="p6-iv6-reset">Сброс</button>'
    +'</div>'
    +'</div>';
`;

const P6_INIT = `
function _initP6_iv6(){
  const sb = document.getElementById('p6-iv6-sandbox');
  if (!sb || !window.P8Helpers || !window.P8Anim) return;
  const svg = P8Helpers.svg.create(560, 240);
  svg.setAttribute('width','100%'); svg.setAttribute('height','100%'); svg.style.display='block';
  sb.appendChild(svg);
  /* Vessel positions (will animate to centre on mix) */
  const v1 = { x: 140, y: 130, m: 0.5, T: 80, color: '#fb923c' };
  const v2 = { x: 420, y: 130, m: 1.0, T: 20, color: '#7dd3fc' };
  const finalState = { active: false, T: 50, fillFraction: 0.5 };
  function drawVessel(x, y, m, T, color){
    const g = P8Helpers.svg.el('g', { transform: 'translate('+x+','+y+')' });
    const h = 30 + m * 50;
    const w = 70;
    /* Glass */
    g.appendChild(P8Helpers.svg.el('rect', { x:-w/2, y:-h, width:w, height:h, rx:6, fill:'rgba(255,255,255,.6)', stroke:'#0f172a', 'stroke-width':1.5 }));
    /* Liquid */
    g.appendChild(P8Helpers.svg.el('rect', { x:-w/2+3, y:-h+5, width:w-6, height:h-8, rx:4, fill: P8Helpers.thermal.tempColor(T/100) }));
    /* Label */
    g.appendChild(P8Helpers.svg.el('text', { x:0, y:18, 'font-family':"'JetBrains Mono',monospace", 'font-size':11, 'font-weight':700, fill:'#0f172a', 'text-anchor':'middle', text: 'm='+m.toFixed(1)+' кг' }));
    g.appendChild(P8Helpers.svg.el('text', { x:0, y:32, 'font-family':"'JetBrains Mono',monospace", 'font-size':11, 'font-weight':700, fill:'#0f172a', 'text-anchor':'middle', text: 'T='+Math.round(T)+'°C' }));
    return g;
  }
  let v1G = drawVessel(v1.x, v1.y, v1.m, v1.T, v1.color);
  let v2G = drawVessel(v2.x, v2.y, v2.m, v2.T, v2.color);
  svg.appendChild(v1G); svg.appendChild(v2G);
  function redraw(){
    svg.innerHTML = '';
    if (!finalState.active) {
      v1G = drawVessel(v1.x, v1.y, v1.m, v1.T, v1.color);
      v2G = drawVessel(v2.x, v2.y, v2.m, v2.T, v2.color);
      svg.appendChild(v1G); svg.appendChild(v2G);
    } else {
      /* Single combined vessel */
      const cv = drawVessel(280, 130, v1.m + v2.m, finalState.T, P8Helpers.thermal.tempColor(finalState.T/100));
      svg.appendChild(cv);
      /* Result label */
      svg.appendChild(P8Helpers.svg.el('text', { x:280, y:60, 'font-family':"'Unbounded',sans-serif", 'font-size':14, 'font-weight':800, fill:'var(--th-mid,#f97316)', 'text-anchor':'middle', text: 'T_итог = '+Math.round(finalState.T)+' °C' }));
    }
  }
  /* Hook up scrubbers */
  function bindScrub(inputId, valId, obj, prop){
    const input = document.getElementById(inputId);
    const lab = document.getElementById(valId);
    if (!input || !lab) return;
    input.addEventListener('input', () => {
      const v = parseFloat(input.value);
      obj[prop] = v;
      lab.textContent = v.toFixed(prop === 'm' ? 1 : 0);
      if (finalState.active) {
        finalState.active = false;
        document.getElementById('p6-iv6-tf').textContent = '—';
      }
      redraw();
    });
  }
  bindScrub('p6-iv6-m1', 'p6-iv6-m1-val', v1, 'm');
  bindScrub('p6-iv6-t1', 'p6-iv6-t1-val', v1, 'T');
  bindScrub('p6-iv6-m2', 'p6-iv6-m2-val', v2, 'm');
  bindScrub('p6-iv6-t2', 'p6-iv6-t2-val', v2, 'T');
  /* Mix button */
  document.getElementById('p6-iv6-mix').onclick = () => {
    const T = (v1.m * v1.T + v2.m * v2.T) / (v1.m + v2.m);
    finalState.active = true;
    finalState.T = T;
    P8Anim.tween({
      from: v1.T, to: T, duration: 1200, easing: 'cubicInOut',
      onUpdate: t => {
        finalState.T = t;
        redraw();
        document.getElementById('p6-iv6-tf').textContent = Math.round(t);
      }
    });
    if (window.addXp) addXp(10, 'p6-iv6-mix');
  };
  document.getElementById('p6-iv6-reset').onclick = () => {
    finalState.active = false;
    document.getElementById('p6-iv6-tf').textContent = '—';
    redraw();
  };
  redraw();
}
`;
replaceStub('p6', P6_HTML, P6_INIT);

// =====================================================================
// §8 — Phase Diagram T(t)
// =====================================================================
const P8_HTML = `
  /* IV6 — Phase Diagram T(t) (Phase 1.2) */
  h += '<div class="wg p8-iv6">'
    +'<div class="wg-header"><span class="wg-badge p8-badge p8-badge-thermal">IV-6</span><div class="wg-title">График плавления — почему T не растёт?</div></div>'
    +'<div class="wg-help">Запусти нагрев льда и наблюдай за графиком T(t). При плавлении энергия идёт на разрушение кристаллической решётки — T держится постоянной (плато при 0°C). Двигай ползунок мощности нагревателя — крутизна меняется.</div>'
    +'<div class="p8-sandbox" id="p8-iv6-sandbox" style="height:280px"></div>'
    +'<div style="margin-top:12px;display:flex;gap:14px;flex-wrap:wrap">'
      +'<div class="p8-scrubber" style="flex:1;min-width:200px"><span class="p8-scrubber-label">Мощность</span><input type="range" id="p8-iv6-pwr" min="100" max="2000" step="50" value="500"><span class="p8-scrubber-value"><span id="p8-iv6-pwr-val">500</span><span class="p8-unit">Вт</span></span></div>'
      +'<div class="p8-readout"><span class="p8-readout-label">Фаза</span><span class="p8-readout-value" id="p8-iv6-phase">лёд</span></div>'
      +'<div class="p8-readout"><span class="p8-readout-label">T</span><span class="p8-readout-value" id="p8-iv6-temp">-20</span><span class="p8-readout-unit">°C</span></div>'
      +'<button class="btn primary" id="p8-iv6-play">Старт</button>'
      +'<button class="btn" id="p8-iv6-reset">Сброс</button>'
    +'</div>'
    +'</div>';
`;

const P8_INIT = `
function _initP8_iv6(){
  const sb = document.getElementById('p8-iv6-sandbox');
  if (!sb || !window.P8Helpers || !window.P8Anim) return;
  const W = 560, H = 280;
  const svg = P8Helpers.svg.create(W, H);
  svg.setAttribute('width','100%'); svg.setAttribute('height','100%'); svg.style.display='block';
  sb.appendChild(svg);
  /* Sim state */
  const m = 0.5; // kg ice
  const c_ice = 2100;
  const c_water = 4200;
  const lambda = 330000;
  const r_vap = 2300000;
  let power = 500;
  let energyAccumulated = 0;
  let running = false;
  let raf = null;
  let points = [{ t: 0, T: -20 }];
  /* Axes */
  const pad = { l: 50, r: 18, t: 22, b: 32 };
  const plotW = W - pad.l - pad.r;
  const plotH = H - pad.t - pad.b;
  /* Background */
  svg.appendChild(P8Helpers.svg.el('rect', { x: pad.l, y: pad.t, width: plotW, height: plotH, fill: '#fafafa', stroke: '#e5e7eb' }));
  /* Y axis: -20 to 120 °C */
  const yMin = -20, yMax = 120;
  function yToPx(T) { return pad.t + plotH * (1 - (T - yMin) / (yMax - yMin)); }
  function tToPx(t) { return pad.l + plotW * Math.min(1, t / 300); } // 300 s scale
  /* Y ticks */
  [-20, 0, 20, 40, 60, 80, 100, 120].forEach(t => {
    const y = yToPx(t);
    svg.appendChild(P8Helpers.svg.el('line', { x1: pad.l, y1: y, x2: pad.l + plotW, y2: y, stroke: '#e5e7eb' }));
    svg.appendChild(P8Helpers.svg.el('text', { x: pad.l - 6, y: y + 3, 'font-family':"'JetBrains Mono',monospace", 'font-size': 10, fill: 'var(--p8-muted,#64748b)', 'text-anchor':'end', text: t+'°' }));
  });
  /* Phase regions overlays (transparent) */
  const phaseRegions = [
    { from: -20, to: 0, fill: '#bfdbfe', name: 'лёд' },
    { from: 0, to: 100, fill: '#7dd3fc', name: 'вода' },
    { from: 100, to: 120, fill: '#fde68a', name: 'пар' }
  ];
  phaseRegions.forEach(r => {
    const y1 = yToPx(r.from), y2 = yToPx(r.to);
    svg.appendChild(P8Helpers.svg.el('rect', { x: pad.l, y: y2, width: plotW, height: y1 - y2, fill: r.fill, opacity: 0.18 }));
    svg.appendChild(P8Helpers.svg.el('text', { x: pad.l + plotW - 6, y: (y1 + y2) / 2 + 3, 'font-family':"'Inter',sans-serif", 'font-size': 10, 'font-weight': 700, fill: 'var(--p8-text)', 'text-anchor': 'end', text: r.name }));
  });
  /* Phase lines (0 and 100) */
  svg.appendChild(P8Helpers.svg.el('line', { x1: pad.l, y1: yToPx(0), x2: pad.l + plotW, y2: yToPx(0), stroke: '#0f172a', 'stroke-width': 1, 'stroke-dasharray': '3 3' }));
  svg.appendChild(P8Helpers.svg.el('line', { x1: pad.l, y1: yToPx(100), x2: pad.l + plotW, y2: yToPx(100), stroke: '#0f172a', 'stroke-width': 1, 'stroke-dasharray': '3 3' }));
  /* X axis */
  svg.appendChild(P8Helpers.svg.el('line', { x1: pad.l, y1: pad.t + plotH, x2: pad.l + plotW, y2: pad.t + plotH, stroke: '#0f172a' }));
  svg.appendChild(P8Helpers.svg.el('text', { x: pad.l + plotW / 2, y: H - 6, 'font-family':"'Inter',sans-serif", 'font-size': 11, 'font-weight': 700, fill: 'var(--p8-text)', 'text-anchor': 'middle', text: 'Время, с' }));
  /* Curve path (will be updated) */
  const path = P8Helpers.svg.el('path', { d: '', fill: 'none', stroke: 'var(--th-mid, #f97316)', 'stroke-width': 3, 'stroke-linejoin': 'round', 'stroke-linecap': 'round' });
  svg.appendChild(path);
  function updatePath(){
    if (!points.length) return;
    const d = points.map((p, i) => (i === 0 ? 'M' : 'L') + tToPx(p.t).toFixed(1) + ',' + yToPx(p.T).toFixed(1)).join(' ');
    path.setAttribute('d', d);
  }
  function currentT(){ return points[points.length-1].T; }
  function currentPhase(T){
    if (T < 0) return 'лёд';
    if (T < 100) return T === 0 ? 'плавление' : 'вода';
    if (T === 100) return 'кипение';
    return 'пар';
  }
  function tick(dt){
    if (!running) return;
    const energy = power * dt; // J
    let T = currentT();
    let newT = T;
    if (T < 0) {
      /* heating ice */
      const dT = energy / (c_ice * m);
      newT = T + dT;
      if (newT > 0) newT = 0;
    } else if (T < 0.001 && energyAccumulated < lambda * m) {
      /* phase transition (melting) */
      energyAccumulated += energy;
      newT = 0;
      if (energyAccumulated >= lambda * m) {
        newT = 0.001;
      }
    } else if (T < 100) {
      /* heating water */
      const dT = energy / (c_water * m);
      newT = T + dT;
      if (newT > 100) newT = 100;
    } else if (T < 100.001 && energyAccumulated < (lambda + r_vap) * m) {
      /* phase transition (boiling) */
      energyAccumulated += energy;
      newT = 100;
      if (energyAccumulated >= (lambda + r_vap) * m) {
        newT = 100.001;
      }
    } else if (T < 120) {
      const dT = energy / (c_water * m); // simplified for steam
      newT = T + dT;
      if (newT > 120) newT = 120;
    } else {
      running = false;
    }
    const lastP = points[points.length-1];
    points.push({ t: lastP.t + dt, T: newT });
    if (points.length > 600) points.shift();
    updatePath();
    document.getElementById('p8-iv6-temp').textContent = Math.round(newT);
    document.getElementById('p8-iv6-phase').textContent = currentPhase(newT);
    if (lastP.t > 300) running = false;
  }
  raf = P8Anim.raf(dt => tick(Math.min(dt * 4, 0.5))); // accelerate 4x for demo
  /* Bind controls */
  const pwrInp = document.getElementById('p8-iv6-pwr');
  const pwrLab = document.getElementById('p8-iv6-pwr-val');
  pwrInp.oninput = () => { power = +pwrInp.value; pwrLab.textContent = power; };
  document.getElementById('p8-iv6-play').onclick = () => {
    if (!running) { running = true; raf.start(); if (window.addXp) addXp(10, 'p8-iv6-melt'); }
  };
  document.getElementById('p8-iv6-reset').onclick = () => {
    running = false; raf.stop();
    energyAccumulated = 0;
    points = [{ t: 0, T: -20 }];
    updatePath();
    document.getElementById('p8-iv6-temp').textContent = '-20';
    document.getElementById('p8-iv6-phase').textContent = 'лёд';
  };
  updatePath();
}
`;
replaceStub('p8', P8_HTML, P8_INIT);

fs.writeFileSync(DST, h);
console.log('ch1 size:', h.length);

const scripts = [...h.matchAll(/<script>([\s\S]*?)<\/script>/g)];
for (const m of scripts) {
  try { new Function(m[1]); }
  catch (e) { console.error('JS PARSE FAIL:', e.message.slice(0, 150)); process.exit(1); }
}
console.log('inline JS parses OK');