feat(biochem): единый рендер BIO.render2D + 3D-превью молекул в библиотеке и свойствах

Фаза 0.2 (DRY) + Фаза 1.5 (3D-превью) плана BIOCHEM_UPGRADE:
- library/properties/reactions подключают biochem-core.js; локальные
  дубль-рендереры молекул заменены вызовами BIO.render2D; удалены
  дублирующиеся таблицы ELEM_COLORS/CPK и hexToRgb/cpkColor (~250 строк).
- Библиотека: в детальной панели тумблер 2D/3D — вращающаяся VSEPR-модель
  с подписью формы/гибридизации/угла.
- Свойства: на каждой карточке сравнения тумблер 2D/3D с вращением и
  геометрией; thumbnail-и тоже через общий рендер.
- Fallback-и сохранены (колба в библиотеке, «?» в реакциях, «Нет
  структуры» в свойствах).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/biochem-library.html

@@ -324,8 +324,13 @@
           <div class="detail-name" id="det-name">—</div>
           <div class="detail-lat" id="det-lat"></div>
         </div>
-        <div class="detail-canvas-wrap">
+        <div class="detail-canvas-wrap" style="position:relative">
           <canvas id="det-canvas"></canvas>
+          <button id="det-3d-toggle" onclick="toggleDet3D()" title="2D / 3D"
+            style="position:absolute;top:8px;right:8px;z-index:2;height:26px;padding:0 10px;border-radius:7px;
+                   border:1.5px solid rgba(255,255,255,.15);background:rgba(15,15,30,.85);color:#aaa;
+                   font:700 .72rem Manrope,sans-serif;cursor:pointer">3D</button>
+          <div id="det-geom" style="position:absolute;bottom:6px;left:8px;right:8px;font:600 .66rem Manrope,sans-serif;color:#8aa;display:none;text-align:center"></div>
         </div>
         <div class="detail-section">
           <div class="detail-label">Категория</div>
@@ -352,6 +357,7 @@
 </div>
 
 <script src="/js/api.js"></script>
+  <script src="/js/biochem-core.js"></script>
   <script src="/js/sidebar.js"></script>
 <script src="https://cdn.jsdelivr.net/npm/lucide@0.469.0/dist/umd/lucide.min.js"></script>
 <script>
@@ -367,111 +373,30 @@ if (isAdmin)   document.getElementById('btn-admin').style.display = '';
 if (isTeacher) document.getElementById('btn-classes').style.display = '';
 LS.showBoardIfAllowed();
 
-// ── CPK element colours ──
-const ELEM_COLORS = {
-  H:  { color:'#D4D4D4', text:'#222', r:9  },
-  C:  { color:'#555555', text:'#fff', r:10 },
-  N:  { color:'#4060FF', text:'#fff', r:10 },
-  O:  { color:'#EE2020', text:'#fff', r:10 },
-  P:  { color:'#FF8000', text:'#fff', r:11 },
-  S:  { color:'#C8B400', text:'#000', r:11 },
-  Cl: { color:'#00A860', text:'#fff', r:11 },
-  Na: { color:'#8040C0', text:'#fff', r:11 },
-  Ca: { color:'#707070', text:'#fff', r:11 },
-  Mg: { color:'#1E8A1E', text:'#fff', r:11 },
-  Fe: { color:'#B03010', text:'#fff', r:11 },
-  Br: { color:'#8B4513', text:'#fff', r:11 },
-  I:  { color:'#580DAB', text:'#fff', r:11 },
-  F:  { color:'#B0FFB0', text:'#222', r:9  },
-};
-
-// ── Molecule thumbnail renderer ──
+// ── Molecule thumbnail renderer (delegates to shared BIO.render2D) ──
 function renderMolThumb(canvas, atoms, bonds) {
   const W = canvas.width, H = canvas.height;
   const ctx = canvas.getContext('2d');
-  ctx.clearRect(0, 0, W, H);
-
-  if (!atoms || !atoms.length) {
-    // flask outline fallback
-    const fw = Math.min(W, H) * 0.32, fx = W/2, fy = H/2 + fw*0.05;
-    ctx.strokeStyle = '#555';
-    ctx.lineWidth = Math.max(1.5, fw * 0.07);
-    ctx.lineCap = 'round'; ctx.lineJoin = 'round';
-    ctx.beginPath();
-    ctx.moveTo(fx - fw*0.22, fy - fw*0.52);
-    ctx.lineTo(fx - fw*0.22, fy - fw*0.08);
-    ctx.lineTo(fx - fw*0.55, fy + fw*0.42);
-    ctx.quadraticCurveTo(fx, fy + fw*0.62, fx + fw*0.55, fy + fw*0.42);
-    ctx.lineTo(fx + fw*0.22, fy - fw*0.08);
-    ctx.lineTo(fx + fw*0.22, fy - fw*0.52);
-    ctx.moveTo(fx - fw*0.32, fy - fw*0.52);
-    ctx.lineTo(fx + fw*0.32, fy - fw*0.52);
-    ctx.stroke();
+  if (atoms && atoms.length) {
+    BIO.render2D(ctx, atoms, bonds || [], { fit: true, padding: Math.min(W, H) * 0.16 });
     return;
   }
-
-  let minX = Infinity, minY = Infinity, maxX = -Infinity, maxY = -Infinity;
-  for (const a of atoms) {
-    const x = a.x ?? 0, y = a.y ?? 0;
-    minX = Math.min(minX, x); minY = Math.min(minY, y);
-    maxX = Math.max(maxX, x); maxY = Math.max(maxY, y);
-  }
-
-  const pad = Math.min(W, H) * 0.16;
-  const rangeX = maxX - minX || 1, rangeY = maxY - minY || 1;
-  const scale  = Math.min((W - pad*2) / rangeX, (H - pad*2) / rangeY);
-  const offX   = (W - rangeX * scale) / 2 - minX * scale;
-  const offY   = (H - rangeY * scale) / 2 - minY * scale;
-  const sx = ax => ax * scale + offX;
-  const sy = ay => ay * scale + offY;
-
-  // bonds
-  for (const b of bonds) {
-    const f = b.f ?? b.from, t = b.t ?? b.to, order = b.o ?? b.order ?? 1;
-    const af = atoms.find(a => a.id === f), at_ = atoms.find(a => a.id === t);
-    if (!af || !at_) continue;
-    const x1 = sx(af.x??0), y1 = sy(af.y??0);
-    const x2 = sx(at_.x??0), y2 = sy(at_.y??0);
-    ctx.strokeStyle = 'rgba(180,180,200,0.65)';
-    ctx.lineWidth = Math.max(1, scale * 0.75); ctx.lineCap = 'round';
-    if (order === 1) {
-      ctx.beginPath(); ctx.moveTo(x1,y1); ctx.lineTo(x2,y2); ctx.stroke();
-    } else {
-      const dx = x2-x1, dy = y2-y1, len = Math.hypot(dx,dy)||1;
-      const nx = -dy/len, ny = dx/len, gap = Math.max(1.5, scale * 0.85);
-      const offsets = order === 2 ? [-gap/2, gap/2] : [-gap, 0, gap];
-      for (const o of offsets) {
-        ctx.beginPath(); ctx.moveTo(x1+nx*o, y1+ny*o); ctx.lineTo(x2+nx*o, y2+ny*o); ctx.stroke();
-      }
-    }
-  }
-
-  // atoms
-  const minR = Math.max(6, Math.min(W, H) * 0.065);
-  for (const a of atoms) {
-    const x = sx(a.x??0), y = sy(a.y??0);
-    const el = ELEM_COLORS[a.s] || { color:'#888', text:'#fff', r:10 };
-    const r = Math.max(minR * 0.65, (el.r / 20) * minR);
-    // sphere gradient
-    const grd = ctx.createRadialGradient(x-r*0.3,y-r*0.35,r*0.05,x,y,r);
-    const [hr,hg,hb] = hexToRgb(el.color);
-    grd.addColorStop(0,   `rgb(${Math.min(255,hr+90)},${Math.min(255,hg+90)},${Math.min(255,hb+90)})`);
-    grd.addColorStop(0.5, el.color);
-    grd.addColorStop(1,   `rgb(${Math.round(hr*.3)},${Math.round(hg*.3)},${Math.round(hb*.3)})`);
-    ctx.beginPath(); ctx.arc(x,y,r,0,Math.PI*2);
-    ctx.fillStyle = grd; ctx.fill();
-    const fs = Math.max(6, r * (a.s.length > 1 ? 0.72 : 0.92));
-    ctx.fillStyle = el.text;
-    ctx.font = `700 ${fs}px Manrope,sans-serif`;
-    ctx.textAlign = 'center'; ctx.textBaseline = 'middle';
-    ctx.fillText(a.s, x, y);
-  }
-}
-function hexToRgb(hex) {
-  hex = hex.replace('#','');
-  if (hex.length===3) hex=hex.split('').map(c=>c+c).join('');
-  const n=parseInt(hex,16);
-  return [(n>>16)&255,(n>>8)&255,n&255];
+  // flask outline fallback
+  ctx.clearRect(0, 0, W, H);
+  const fw = Math.min(W, H) * 0.32, fx = W/2, fy = H/2 + fw*0.05;
+  ctx.strokeStyle = '#555';
+  ctx.lineWidth = Math.max(1.5, fw * 0.07);
+  ctx.lineCap = 'round'; ctx.lineJoin = 'round';
+  ctx.beginPath();
+  ctx.moveTo(fx - fw*0.22, fy - fw*0.52);
+  ctx.lineTo(fx - fw*0.22, fy - fw*0.08);
+  ctx.lineTo(fx - fw*0.55, fy + fw*0.42);
+  ctx.quadraticCurveTo(fx, fy + fw*0.62, fx + fw*0.55, fy + fw*0.42);
+  ctx.lineTo(fx + fw*0.22, fy - fw*0.08);
+  ctx.lineTo(fx + fw*0.22, fy - fw*0.52);
+  ctx.moveTo(fx - fw*0.32, fy - fw*0.52);
+  ctx.lineTo(fx + fw*0.32, fy - fw*0.52);
+  ctx.stroke();
 }
 
 // ── Data ──
@@ -620,15 +545,58 @@ async function selectMol(id) {
 
     document.getElementById('det-open-btn').dataset.id = id;
 
+    _detMol = m;
     const cvs = document.getElementById('det-canvas');
     cvs.width  = cvs.offsetWidth  || 252;
     cvs.height = cvs.offsetHeight || 252;
-    renderMolThumb(cvs, m.atoms_json || [], m.bonds_json || []);
+    _renderDetail();
   } catch(e) {
     document.getElementById('det-name').textContent = 'Ошибка загрузки';
   }
 }
 
+// ── Detail 2D/3D view ──
+let _detMol = null, _det3D = false, _det3dRotY = 0.4, _det3dRotX = 0.35, _detAnim = null;
+function _stopDetAnim() { if (_detAnim) { cancelAnimationFrame(_detAnim); _detAnim = null; } }
+
+function _renderDetail() {
+  _stopDetAnim();
+  const cvs = document.getElementById('det-canvas');
+  if (!cvs || !_detMol) return;
+  const ctx = cvs.getContext('2d');
+  const atoms = _detMol.atoms_json || [], bonds = _detMol.bonds_json || [];
+  const geomEl = document.getElementById('det-geom');
+  const tgl = document.getElementById('det-3d-toggle');
+
+  if (!_det3D || !atoms.length) {
+    geomEl.style.display = 'none';
+    if (tgl) { tgl.textContent = '3D'; tgl.style.color = '#aaa'; }
+    renderMolThumb(cvs, atoms, bonds);
+    return;
+  }
+
+  // 3D: build VSEPR geometry once, spin it
+  const g = BIO.vsepr(atoms, bonds);
+  if (g.shape) {
+    geomEl.style.display = 'block';
+    geomEl.textContent = [g.shape, g.hybridization, g.angle != null ? g.angle + '°' : '']
+      .filter(Boolean).join(' · ');
+  }
+  if (tgl) { tgl.textContent = '2D'; tgl.style.color = '#06D6E0'; }
+  let ext = 1;
+  for (const a of g.atoms3d) ext = Math.max(ext, Math.hypot(a.x, a.y, a.z));
+  const sc = Math.max(0.4, Math.min(3, (Math.min(cvs.width, cvs.height) * 0.40) / (ext * 1.6 + 30)));
+  const frame = () => {
+    if (!_det3D) return;
+    _det3dRotY += 0.012;
+    BIO.render3D(ctx, g.atoms3d, bonds, { rotX: _det3dRotX, rotY: _det3dRotY, scale: sc, W: cvs.width, H: cvs.height }, { vdw: false, bg: '#0a0a16' });
+    _detAnim = requestAnimationFrame(frame);
+  };
+  frame();
+}
+
+function toggleDet3D() { _det3D = !_det3D; _renderDetail(); }
+
 function openInEditor() {
   const id = document.getElementById('det-open-btn').dataset.id;
   if (id) openInEditorId(id);

frontend/biochem-properties.html

@@ -238,6 +238,7 @@
 </div>
 
 <script src="/js/api.js"></script>
+  <script src="/js/biochem-core.js"></script>
   <script src="/js/sidebar.js"></script>
 <script src="https://cdn.jsdelivr.net/npm/lucide@0.469.0/dist/umd/lucide.min.js"></script>
 <script>
@@ -261,15 +262,6 @@ const ATOMIC_MASS = {
   Ag:107.868, Ba:137.327, Mn:54.938,
 };
 
-// ── CPK colors (for canvas thumbnails) ──
-const CPK = {
-  H:'#D4D4D4', C:'#555555', N:'#4060FF', O:'#EE2020', P:'#FF8000',
-  S:'#C8B400', Cl:'#00A860', Na:'#8040C0', Ca:'#707070', K:'#8040C0',
-  Mg:'#1E8A1E', Fe:'#B03010', Br:'#8B2222', F:'#90E050', Al:'#BFA6A6',
-};
-
-function cpkColor(sym) { return CPK[sym] || '#888'; }
-
 function molarMass(formula) {
   let mass = 0;
   const re = /([A-Z][a-z]*)(\d*)/g;
@@ -377,45 +369,9 @@ function renderMolList() {
 function drawThumb(mol) {
   const canvas = document.getElementById('thumb-'+mol.id);
   if (!canvas) return;
-  const ctx = canvas.getContext('2d');
-  const W = 34, H = 34;
-  ctx.clearRect(0,0,W,H);
-  ctx.fillStyle = '#08080f';
-  ctx.fillRect(0,0,W,H);
   const atoms = mol.atoms_json || [];
-  const bonds = mol.bonds_json || [];
-  if (!atoms.length) return;
-  let minX=Infinity,minY=Infinity,maxX=-Infinity,maxY=-Infinity;
-  for (const a of atoms) { minX=Math.min(minX,a.x??a.id); minY=Math.min(minY,a.y??0); maxX=Math.max(maxX,a.x??a.id); maxY=Math.max(maxY,a.y??0); }
-  const pad=6, molW=Math.max(maxX-minX,1), molH=Math.max(maxY-minY,1);
-  const sc=Math.min((W-pad*2)/molW,(H-pad*2)/molH);
-  const ox=pad+(W-pad*2-molW*sc)/2, oy=pad+(H-pad*2-molH*sc)/2;
-  const sx=a=>ox+(a.x-minX)*sc, sy=a=>oy+(a.y-minY)*sc;
-  // bonds
-  ctx.strokeStyle='rgba(180,180,200,.5)'; ctx.lineWidth=1;
-  for (const b of bonds) {
-    const a1=atoms.find(a=>a.id===b.from||(b.f&&a.id===b.f)), a2=atoms.find(a=>a.id===b.to||(b.t&&a.id===b.t));
-    if (!a1||!a2) continue;
-    ctx.beginPath(); ctx.moveTo(sx(a1),sy(a1)); ctx.lineTo(sx(a2),sy(a2)); ctx.stroke();
-  }
-  // atoms
-  for (const a of atoms) {
-    const r = Math.max(2, 4*sc);
-    const col = cpkColor(a.s);
-    ctx.beginPath(); ctx.arc(sx(a),sy(a),r,0,Math.PI*2);
-    const [r0,g0,b0] = hexRgb(col);
-    const grd = ctx.createRadialGradient(sx(a)-r*.3,sy(a)-r*.35,r*.05,sx(a),sy(a),r);
-    grd.addColorStop(0,`rgb(${Math.min(255,r0+80)},${Math.min(255,g0+80)},${Math.min(255,b0+80)})`);
-    grd.addColorStop(1,`rgb(${Math.round(r0*.3)},${Math.round(g0*.3)},${Math.round(b0*.3)})`);
-    ctx.fillStyle=grd; ctx.fill();
-  }
-}
-
-function hexRgb(hex) {
-  hex=hex.replace('#','');
-  if(hex.length===3)hex=hex.split('').map(c=>c+c).join('');
-  const n=parseInt(hex,16);
-  return[(n>>16)&255,(n>>8)&255,n&255];
+  if (!atoms.length) { const c = canvas.getContext('2d'); c.clearRect(0,0,34,34); c.fillStyle='#08080f'; c.fillRect(0,0,34,34); return; }
+  BIO.render2D(canvas.getContext('2d'), atoms, mol.bonds_json || [], { fit:true, padding:6, bg:'#08080f', showSymbols:false });
 }
 
 function toggleCompare(id) {
@@ -454,9 +410,14 @@ function renderCompare() {
     const phys = getPhysProps(mol.formula);
     html += `
     <div class="compare-card">
-      <div class="cc-canvas-wrap">
+      <div class="cc-canvas-wrap" style="position:relative">
         <canvas id="ccc-${mol.id}" width="200" height="160"></canvas>
         <button class="cc-remove" onclick="removeFromCompare(${mol.id})" title="Убрать"><svg class="ic" viewBox="0 0 24 24"><line x1="18" y1="6" x2="6" y2="18"/><line x1="6" y1="6" x2="18" y2="18"/></svg></button>
+        <button id="cc3d-${mol.id}" onclick="toggleCompareCard3D(${mol.id})" title="2D / 3D"
+          style="position:absolute;top:6px;left:6px;z-index:2;height:22px;padding:0 8px;border-radius:6px;
+                 border:1.5px solid rgba(255,255,255,.15);background:rgba(15,15,30,.85);color:#aaa;
+                 font:700 .66rem Manrope,sans-serif;cursor:pointer">3D</button>
+        <div id="ccgeom-${mol.id}" style="position:absolute;bottom:4px;left:4px;right:4px;font:600 .6rem Manrope,sans-serif;color:#8aa;display:none;text-align:center;pointer-events:none"></div>
       </div>
       <div class="cc-body">
         <div class="cc-formula">${mol.formula}</div>
@@ -528,55 +489,62 @@ function renderCompare() {
   }, 0);
 }
 
+// Per-card 3D view state: id -> { on, rotY, anim }
+const _cc3d = {};
+function _stopCC(id) { const s = _cc3d[id]; if (s && s.anim) { cancelAnimationFrame(s.anim); s.anim = null; } }
+
 function drawCompareCanvas(mol) {
   const canvas = document.getElementById('ccc-'+mol.id);
   if (!canvas) return;
   const W = canvas.offsetWidth || 200, H = canvas.offsetHeight || 160;
   canvas.width = W; canvas.height = H;
   const ctx = canvas.getContext('2d');
-  ctx.fillStyle = '#08080f';
-  ctx.fillRect(0,0,W,H);
-  const atoms = mol.atoms_json || [];
-  const bonds = mol.bonds_json || [];
+  const atoms = mol.atoms_json || [], bonds = mol.bonds_json || [];
+  const tgl = document.getElementById('cc3d-'+mol.id);
+  const geomEl = document.getElementById('ccgeom-'+mol.id);
+  _stopCC(mol.id);
+
   if (!atoms.length) {
-    ctx.fillStyle = '#444';
-    ctx.font = '0.8rem Manrope,sans-serif';
+    ctx.fillStyle = '#08080f'; ctx.fillRect(0,0,W,H);
+    ctx.fillStyle = '#444'; ctx.font = '0.8rem Manrope,sans-serif';
     ctx.textAlign = 'center'; ctx.textBaseline = 'middle';
     ctx.fillText('Нет структуры', W/2, H/2);
+    if (tgl) tgl.style.display = 'none';
     return;
   }
-  let minX=Infinity,minY=Infinity,maxX=-Infinity,maxY=-Infinity;
-  for (const a of atoms) { minX=Math.min(minX,a.x); minY=Math.min(minY,a.y); maxX=Math.max(maxX,a.x); maxY=Math.max(maxY,a.y); }
-  const pad=20, molW=Math.max(maxX-minX,1), molH=Math.max(maxY-minY,1);
-  const sc=Math.min((W-pad*2)/molW,(H-pad*2)/molH, 2.5);
-  const ox=W/2-(minX+maxX)*sc/2, oy=H/2-(minY+maxY)*sc/2;
-  const sx=a=>ox+a.x*sc, sy=a=>oy+a.y*sc;
-  // bonds
-  for (const b of bonds) {
-    const a1=atoms.find(a=>a.id===(b.from??b.f)), a2=atoms.find(a=>a.id===(b.to??b.t));
-    if (!a1||!a2) continue;
-    ctx.strokeStyle='rgba(180,180,200,.55)'; ctx.lineWidth=Math.max(1.5,2*sc);
-    ctx.lineCap='round';
-    ctx.beginPath(); ctx.moveTo(sx(a1),sy(a1)); ctx.lineTo(sx(a2),sy(a2)); ctx.stroke();
+  if (tgl) tgl.style.display = '';
+  const state = _cc3d[mol.id] || (_cc3d[mol.id] = { on:false, rotY:0.4 });
+
+  if (!state.on) {
+    if (tgl) { tgl.textContent = '3D'; tgl.style.color = '#aaa'; }
+    if (geomEl) geomEl.style.display = 'none';
+    BIO.render2D(ctx, atoms, bonds, { fit:true, padding:20, bg:'#08080f', maxScale:2.5 });
+    return;
   }
-  // atoms
-  for (const a of atoms) {
-    const r = Math.max(6, 9*sc);
-    const col = cpkColor(a.s);
-    const [r0,g0,b0] = hexRgb(col);
-    const grd = ctx.createRadialGradient(sx(a)-r*.32,sy(a)-r*.38,r*.05,sx(a),sy(a),r);
-    grd.addColorStop(0,`rgb(${Math.min(255,r0+100)},${Math.min(255,g0+100)},${Math.min(255,b0+100)})`);
-    grd.addColorStop(.4, col);
-    grd.addColorStop(1,`rgb(${Math.round(r0*.2)},${Math.round(g0*.2)},${Math.round(b0*.2)})`);
-    ctx.beginPath(); ctx.arc(sx(a),sy(a),r,0,Math.PI*2);
-    ctx.fillStyle=grd; ctx.fill();
-    if (atoms.length <= 15) {
-      ctx.fillStyle = a.s==='C'||a.s==='N'||a.s==='Fe'||a.s==='Mg' ? '#fff' : '#111';
-      ctx.font=`bold ${Math.max(8,Math.round(r*.7))}px Manrope,sans-serif`;
-      ctx.textAlign='center'; ctx.textBaseline='middle';
-      ctx.fillText(a.s,sx(a),sy(a));
-    }
+  // 3D spinning
+  if (tgl) { tgl.textContent = '2D'; tgl.style.color = '#06D6E0'; }
+  const g = BIO.vsepr(atoms, bonds);
+  if (geomEl && g.shape) {
+    geomEl.style.display = 'block';
+    geomEl.textContent = [g.shape, g.hybridization, g.angle != null ? g.angle + '°' : ''].filter(Boolean).join(' · ');
   }
+  let ext = 1; for (const a of g.atoms3d) ext = Math.max(ext, Math.hypot(a.x, a.y, a.z));
+  const sc = Math.max(0.4, Math.min(2.6, (Math.min(W, H) * 0.40) / (ext * 1.6 + 30)));
+  const frame = () => {
+    if (!state.on) return;
+    state.rotY += 0.012;
+    BIO.render3D(ctx, g.atoms3d, bonds, { rotX:0.35, rotY:state.rotY, scale:sc, W, H }, { vdw:false, bg:'#0a0a16' });
+    state.anim = requestAnimationFrame(frame);
+  };
+  frame();
+}
+
+function toggleCompareCard3D(id) {
+  const mol = _compare.find(c => c.id === id);
+  if (!mol) return;
+  const s = _cc3d[id] || (_cc3d[id] = { on:false, rotY:0.4 });
+  s.on = !s.on;
+  drawCompareCanvas(mol);
 }
 
 init();

frontend/biochem-reactions.html

@@ -358,6 +358,7 @@
 </div>
 
 <script src="/js/api.js"></script>
+  <script src="/js/biochem-core.js"></script>
   <script src="/js/sidebar.js"></script>
 <script src="https://cdn.jsdelivr.net/npm/lucide@0.469.0/dist/umd/lucide.min.js"></script>
 <script>
@@ -373,92 +374,23 @@ if (isAdmin)   document.getElementById('btn-admin').style.display = '';
 if (isTeacher) document.getElementById('btn-classes').style.display = '';
 LS.showBoardIfAllowed();
 
-// ── CPK colours ──
-const ELEM_COLORS = {
-  H:  { color:'#D4D4D4', text:'#222', r:9  },
-  C:  { color:'#555555', text:'#fff', r:10 },
-  N:  { color:'#4060FF', text:'#fff', r:10 },
-  O:  { color:'#EE2020', text:'#fff', r:10 },
-  P:  { color:'#FF8000', text:'#fff', r:11 },
-  S:  { color:'#C8B400', text:'#000', r:11 },
-  Cl: { color:'#00A860', text:'#fff', r:11 },
-  Na: { color:'#8040C0', text:'#fff', r:11 },
-  Ca: { color:'#707070', text:'#fff', r:11 },
-  Mg: { color:'#1E8A1E', text:'#fff', r:11 },
-  Fe: { color:'#B03010', text:'#fff', r:11 },
-  Br: { color:'#8B4513', text:'#fff', r:11 },
-  I:  { color:'#580DAB', text:'#fff', r:11 },
-  F:  { color:'#B0FFB0', text:'#222', r:9  },
-};
-
-function hexToRgb(hex) {
-  hex = hex.replace('#','');
-  if (hex.length===3) hex=hex.split('').map(c=>c+c).join('');
-  const n=parseInt(hex,16);
-  return [(n>>16)&255,(n>>8)&255,n&255];
-}
-
 function renderMolThumb(canvas, atoms, bonds) {
   const W = canvas.width, H = canvas.height;
   const ctx = canvas.getContext('2d');
-  ctx.clearRect(0, 0, W, H);
-  if (!atoms || !atoms.length) {
-    ctx.fillStyle = '#4b5563';
-    ctx.beginPath();
-    ctx.arc(W/2, H/2, Math.min(W,H)*0.18, 0, Math.PI*2);
-    ctx.fill();
-    ctx.fillStyle = '#9ca3af';
-    ctx.font = `bold ${Math.floor(Math.min(W,H)*0.22)}px sans-serif`;
-    ctx.textAlign = 'center'; ctx.textBaseline = 'middle';
-    ctx.fillText('?', W/2, H/2);
+  if (atoms && atoms.length) {
+    BIO.render2D(ctx, atoms, bonds || [], { fit:true, padding:Math.min(W,H)*0.15 });
     return;
   }
-  let minX=Infinity, minY=Infinity, maxX=-Infinity, maxY=-Infinity;
-  for (const a of atoms) {
-    const x=a.x??0, y=a.y??0;
-    minX=Math.min(minX,x); minY=Math.min(minY,y);
-    maxX=Math.max(maxX,x); maxY=Math.max(maxY,y);
-  }
-  const pad=Math.min(W,H)*0.15;
-  const rangeX=maxX-minX||1, rangeY=maxY-minY||1;
-  const scale=Math.min((W-pad*2)/rangeX,(H-pad*2)/rangeY);
-  const offX=(W-rangeX*scale)/2-minX*scale;
-  const offY=(H-rangeY*scale)/2-minY*scale;
-  const sx=ax=>ax*scale+offX, sy=ay=>ay*scale+offY;
-
-  for (const b of bonds) {
-    const f=b.f??b.from, t=b.t??b.to, order=b.o??b.order??1;
-    const af=atoms.find(a=>a.id===f), at_=atoms.find(a=>a.id===t);
-    if (!af||!at_) continue;
-    const x1=sx(af.x??0), y1=sy(af.y??0), x2=sx(at_.x??0), y2=sy(at_.y??0);
-    ctx.strokeStyle='rgba(180,180,200,0.6)';
-    ctx.lineWidth=Math.max(1,scale*0.75); ctx.lineCap='round';
-    if (order===1) { ctx.beginPath(); ctx.moveTo(x1,y1); ctx.lineTo(x2,y2); ctx.stroke(); }
-    else {
-      const dx=x2-x1, dy=y2-y1, len=Math.hypot(dx,dy)||1;
-      const nx=-dy/len, ny=dx/len, gap=Math.max(1.5,scale*0.85);
-      const offsets=order===2?[-gap/2,gap/2]:[-gap,0,gap];
-      for (const o of offsets) { ctx.beginPath(); ctx.moveTo(x1+nx*o,y1+ny*o); ctx.lineTo(x2+nx*o,y2+ny*o); ctx.stroke(); }
-    }
-  }
-  const minR=Math.max(5,Math.min(W,H)*0.065);
-  for (const a of atoms) {
-    const x=sx(a.x??0), y=sy(a.y??0);
-    const el=ELEM_COLORS[a.s]||{color:'#888',text:'#fff',r:10};
-    const r=Math.max(minR*0.6,(el.r/20)*minR);
-    const [hr,hg,hb]=hexToRgb(el.color);
-    const grd=ctx.createRadialGradient(x-r*0.3,y-r*0.35,r*0.05,x,y,r);
-    grd.addColorStop(0,`rgb(${Math.min(255,hr+90)},${Math.min(255,hg+90)},${Math.min(255,hb+90)})`);
-    grd.addColorStop(0.5,el.color);
-    grd.addColorStop(1,`rgb(${Math.round(hr*.3)},${Math.round(hg*.3)},${Math.round(hb*.3)})`);
-    ctx.beginPath(); ctx.arc(x,y,r,0,Math.PI*2);
-    ctx.fillStyle=grd; ctx.fill();
-    const fs=Math.max(5,r*(a.s.length>1?0.7:0.9));
-    ctx.fillStyle=el.text;
-    ctx.font=`700 ${fs}px Manrope,sans-serif`;
-    ctx.textAlign='center'; ctx.textBaseline='middle';
-    ctx.fillText(a.s,x,y);
-  }
+  // unknown-structure fallback: "?"
+  ctx.clearRect(0, 0, W, H);
+  ctx.fillStyle = '#4b5563';
+  ctx.beginPath();
+  ctx.arc(W/2, H/2, Math.min(W,H)*0.18, 0, Math.PI*2);
+  ctx.fill();
+  ctx.fillStyle = '#9ca3af';
+  ctx.font = `bold ${Math.floor(Math.min(W,H)*0.22)}px sans-serif`;
+  ctx.textAlign = 'center'; ctx.textBaseline = 'middle';
+  ctx.fillText('?', W/2, H/2);
 }
 
 // ── Type metadata ──