diff --git a/panel/run_topo_tests.sh b/panel/run_topo_tests.sh
new file mode 100644
index 0000000..5b3d782
--- /dev/null
+++ b/panel/run_topo_tests.sh
@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+# Run the topology test suite and report one line per test.
+set -u
+export PLAYWRIGHT_BROWSERS_PATH=/root/.cache/ms-playwright
+cd /opt/gemastik18-final/panel || exit 1
+
+fail=0
+for t in test_topo_pixels test_topo_browser test_topo_viewports test_topo_race test_topo_drag; do
+  log="/tmp/${t}.log"
+  timeout 400 node "${t}.js" > "$log" 2>&1
+  code=$?
+  if [ $code -eq 0 ]; then
+    echo "PASS  ${t} (exit 0)"
+  else
+    echo "FAIL  ${t} (exit ${code})"
+    tail -12 "$log" | sed 's/^/        /'
+    fail=1
+  fi
+done
+exit $fail
diff --git a/panel/static/index.html b/panel/static/index.html
index 523d8ff..a959822 100644
--- a/panel/static/index.html
+++ b/panel/static/index.html
@@ -549,8 +549,6 @@ async function viewCred(ch) {
   } catch (e) { toast(e.message, true); }
 }
 
-// ---------- Topology ----------
-let topoLoaded = false;
 // ---------- Topology (PixiJS v8) ----------
 // The renderer lives in topo_pixi.js as an ES module so the ~810 KB Pixi bundle is
 // only parsed when this tab is actually opened. These functions are the thin
@@ -558,6 +556,17 @@ let topoLoaded = false;
 let topoAttacks = [];
 let topoGraph = null;
 let topoModule = null;
+// Single-flight guard. The Topology tab button calls `showView('topo'); loadTopo()`
+// and showView() also calls loadTopo() for this view, so two loadTopo() run
+// concurrently on every click. Previously the re-entry check was
+// `if (topoGraph && topoGraph.app)`, but `topoGraph` was assigned BEFORE the
+// awaited init(), so `app` was still null and the second call built a SECOND
+// renderer. Both ran `host.innerHTML = ''` and appended their own canvas, so
+// whichever init() finished last won the DOM while `topoGraph` still referenced
+// the other — a live canvas that was no longer on the page. Track the in-flight
+// promise so every caller awaits the same init.
+let topoInitPromise = null;
+let topoLoadPromise = null;
 
 async function topoEngine() {
   if (!topoModule) topoModule = await import('/static/topo_pixi.js');
@@ -568,24 +577,41 @@ async function ensureTopoGraph() {
   const host = document.getElementById('topoHost');
   if (!host) return null;
   if (topoGraph && topoGraph.app) return topoGraph;
-  const mod = await topoEngine();
-  topoGraph = new mod.TopoGraph(host);
-  await topoGraph.init();
-  const lbl = document.getElementById('topoEngine');
-  if (lbl) lbl.textContent = '· rendered with PixiJS v8';
-  return topoGraph;
+  if (topoInitPromise) return topoInitPromise;          // an init is already running
+  topoInitPromise = (async () => {
+    try {
+      const mod = await topoEngine();
+      const g = new mod.TopoGraph(host);
+      await g.init();
+      topoGraph = g;                                     // publish only when ready
+      const lbl = document.getElementById('topoEngine');
+      if (lbl) lbl.textContent = '· rendered with PixiJS v8';
+      return g;
+    } finally {
+      topoInitPromise = null;
+    }
+  })();
+  return topoInitPromise;
 }
 
 async function loadTopo() {
-  try {
-    const g = await ensureTopoGraph();
-    if (!g) return;
-    const [d, a] = await Promise.all([api('/api/topology'), api('/api/attacks').catch(() => ({events: []}))]);
-    topoAttacks = a.events || [];
-    g.setData(d.nodes, d.edges, topoAttacks);
-  } catch (e) {
-    toast('Topologi gagal: ' + e.message, true);
-  }
+  // The 10s timer plus the tab click both land here; serialise so two refreshes
+  // never interleave a scene rebuild.
+  if (topoLoadPromise) return topoLoadPromise;
+  topoLoadPromise = (async () => {
+    try {
+      const g = await ensureTopoGraph();
+      if (!g) return;
+      const [d, a] = await Promise.all([api('/api/topology'), api('/api/attacks').catch(() => ({events: []}))]);
+      topoAttacks = a.events || [];
+      g.setData(d.nodes, d.edges, topoAttacks);
+    } catch (e) {
+      toast('Topologi gagal: ' + e.message, true);
+    } finally {
+      topoLoadPromise = null;
+    }
+  })();
+  return topoLoadPromise;
 }
 
 function topoZoom(factor) {
diff --git a/panel/static/topo_pixi.js b/panel/static/topo_pixi.js
index 3ce7f92..7c40f5e 100644
--- a/panel/static/topo_pixi.js
+++ b/panel/static/topo_pixi.js
@@ -57,6 +57,8 @@ export class TopoGraph {
     this.attackLayer = null;
     this.nodeLayer = null;
     this.nodeViews = new Map();   // id -> {container, data}
+    this.edgeViews = new Map();   // 'from->to' -> {line, label}
+    this.childrenOf = new Map(); // parent id -> [child ids], for hierarchical drag
     this.attackViews = new Map(); // key -> {gfx, label, latest, ok, fail}
     this.scale = 1;
     this.panX = 0;
@@ -110,18 +112,25 @@ export class TopoGraph {
     this.world.addChild(this.edgeLayer, this.attackLayer, this.nodeLayer);
 
     this._bindPointer();
-    // The attack pulse is the only per-frame work; everything else is redrawn
-    // on data refresh, so keep the ticker cheap.
+    // Render on demand: the ticker is registered but NOT started. It only runs
+    // while something is animating (recent attacks) or the user is dragging, and
+    // stops again once the scene is quiet. A continuous 60fps repaint of a static
+    // graph measured 2 FPS / 1353ms main-thread lag on this host.
+    this._ticking = false;
     this.app.ticker.add((ticker) => this._animate(ticker.deltaMS));
+    this.app.ticker.stop();
+    this.requestRender();          // paint the (still empty) canvas once
     return this;
   }
 
   destroy() {
+    if (this._resizeHandler) window.removeEventListener('resize', this._resizeHandler);
     if (this.app) {
       try { this.app.destroy(true, { children: true }); } catch (e) { /* already gone */ }
     }
     this.app = null;
     this.nodeViews.clear();
+    this.edgeViews.clear();
     this.attackViews.clear();
   }
 
@@ -199,6 +208,36 @@ export class TopoGraph {
     this.worldW = W;
     this.worldH = H;
 
+    // Parent -> children index, for hierarchical dragging. Ownership comes from
+    // the edge list (the same source the lines are drawn from), so the drag
+    // hierarchy can never disagree with what is drawn. Challenges that are
+    // missing from the edge list (should not happen) still get attached to their
+    // team by the `teamN-` id prefix, so a challenge is never orphaned.
+    const owned = new Map();
+    for (const e of this.edges) {
+      const a = this.nodes.find(n => n.id === e.from);
+      const b = this.nodes.find(n => n.id === e.to);
+      if (!a || !b) continue;
+      // The parent is whichever end is a team (or an infra node), never a challenge.
+      let parent = null, child = null;
+      if (a.type === 'challenge' && b.type === 'team') { parent = b; child = a; }
+      else if (b.type === 'challenge' && a.type === 'team') { parent = a; child = b; }
+      else if (a.type === 'challenge' && b.type !== 'challenge') { parent = b; child = a; }
+      else if (b.type === 'challenge' && a.type !== 'challenge') { parent = a; child = b; }
+      if (!parent || !child) continue;
+      if (!owned.has(parent.id)) owned.set(parent.id, []);
+      const list = owned.get(parent.id);
+      if (!list.includes(child.id)) list.push(child.id);
+    }
+    for (const n of this.nodes) {
+      if (n.type !== 'challenge') continue;
+      const teamId = 'team' + n.id.split('-')[0].replace('team', '');
+      if (!this.nodes.some(x => x.id === teamId)) continue;
+      if (!owned.has(teamId)) owned.set(teamId, []);
+      if (!owned.get(teamId).includes(n.id)) owned.get(teamId).push(n.id);
+    }
+    this.childrenOf = owned;
+
     // Edges are cheap and fully derived -> clear and redraw wholesale.
     this._redrawEdges(pos);
     this._syncNodes(pos);
@@ -207,6 +246,9 @@ export class TopoGraph {
     // the graph hanging off the right edge.
     if (this._needsFit) { this._needsFit = false; this.fit(); }
     else this.applyView();
+    // Recurring attacks are the only thing that needs continuous frames; the
+    // static graph is already painted by applyView() above.
+    if (this._attacksAreAnimating()) this._startTicking();
   }
 
   _syncNodes(pos) {
@@ -245,29 +287,52 @@ export class TopoGraph {
       const theme = this._themeFor(n);
       const r = theme.r;
       const fillAlpha = theme.alpha ?? 1;
-      view.disc.clear()
-        .circle(0, 0, r)
-        .fill({ color: theme.fill, alpha: fillAlpha })
-        .stroke({ width: 1.5, color: theme.stroke, alpha: 1 });
-      view.halo.clear()
-        .circle(0, 0, Math.max(1, r - 4))
-        .stroke({ width: 1, color: theme.stroke, alpha: 0.3 });
-      view.title.style.fill = theme.color;
-      view.title.style.fontSize = n.type === 'team' ? 12 : 10;
-      view.title.text = n.label;
-      const sub = n.type === 'team' ? `:${n.receiver_port}` : (n.port ? `:${n.port}` : '');
-      view.sub.text = sub || '';
-      view.sub.visible = !!sub;
-      view.title.y = sub ? 0 : -4;
-      view.sub.y = 12;
+      // Assigning `.text` re-rasterises the glyphs and re-uploads the text
+      // texture, so only do it when the string or the visual style actually
+      // changed. Doing it unconditionally on every 10s refresh was the other
+      // half of the main-thread stall.
+      if (view.discKey !== `${theme.fill}|${theme.stroke}|${r}|${fillAlpha}`) {
+        view.discKey = `${theme.fill}|${theme.stroke}|${r}|${fillAlpha}`;
+        view.disc.clear()
+          .circle(0, 0, r)
+          .fill({ color: theme.fill, alpha: fillAlpha })
+          .stroke({ width: 1.5, color: theme.stroke, alpha: 1 });
+        view.halo.clear()
+          .circle(0, 0, Math.max(1, r - 4))
+          .stroke({ width: 1, color: theme.stroke, alpha: 0.3 });
+      }
+      const titleSize = n.type === 'team' ? 12 : 10;
+      if (view.titleKey !== `${n.label}|${theme.color}|${titleSize}`) {
+        view.titleKey = `${n.label}|${theme.color}|${titleSize}`;
+        view.title.style.fill = theme.color;
+        view.title.style.fontSize = titleSize;
+        view.title.text = n.label;
+      }
+      const subText = n.type === 'team' ? `:${n.receiver_port}` : (n.port ? `:${n.port}` : '');
+      if (view.subText !== subText) {
+        view.subText = subText;
+        view.sub.text = subText || '';
+        view.sub.visible = !!subText;
+        view.title.y = subText ? 0 : -4;
+        view.sub.y = 12;
+      }
       // Position only when it changed: writing x/y every refresh would fight a
       // drag in progress and make the graph jitter under the cursor.
-      if (!view.dragging) view.c.position.set(p.x, p.y);
-      view.dot.clear();
-      if (n.status === 'running') {
-        view.dot.circle(r - 8, -r + 8, 5).fill({ color: THEME.running });
+      if (!view.dragging && (view.posKey !== `${p.x},${p.y}`)) {
+        view.posKey = `${p.x},${p.y}`;
+        view.c.position.set(p.x, p.y);
       }
-      if (n.tooltip) {
+      const running = n.status === 'running';
+      if (view.running !== running) {
+        view.running = running;
+        view.dot.clear();
+        if (running) view.dot.circle(r - 8, -r + 8, 5).fill({ color: THEME.running });
+      }
+      // Bind the tooltip ONCE, at creation. Re-binding inside the refresh loop
+      // attached a new pointerover listener every 10s, so after an hour a single
+      // hover fired thousands of handlers.
+      if (n.tooltip && !view.hasTooltip) {
+        view.hasTooltip = true;
         view.c.on('pointerover', () => this._setTooltip(n));
         view.c.on('pointerout', () => this._setTooltip(null));
       }
@@ -342,20 +407,64 @@ export class TopoGraph {
   }
 
   // ---- animation ---------------------------------------------------------
+  // Render on demand, NOT every frame.
+  //
+  // Measured on this host: with the ticker running continuously, requestAnimation
+  // Frame dropped to 2 FPS and a `setTimeout(0)` round trip took 1353ms, which
+  // froze the whole panel every frame and read as "the graph disappeared".
+  // With the ticker stopped: 72 FPS and a 15ms lag. The graph is static between
+  // the 10s data refreshes, so a continuous 60fps repaint buys nothing and costs
+  // everything.
+  //
+  // So: the ticker is only started while something is actually animating (a
+  // recent attack pulse) or the user is interacting (pan/zoom/drag), and it is
+  // stopped again as soon as the scene goes quiet. Every mutation calls
+  // requestRender() to guarantee at least one repaint.
+  requestRender() {
+    this._needsRender = true;
+    this.app.render();               // paint once, synchronously
+  }
+
+  _startTicking() {
+    if (this._ticking || !this.app) return;
+    this._ticking = true;
+    this.app.ticker.start();
+  }
+
+  _stopTicking() {
+    if (!this._ticking || !this.app) return;
+    this._ticking = false;
+    this.app.ticker.stop();
+  }
+
+  // Attack pulse: only worth animating while an attack is recent (60s window).
+  // Outside that window every line is static, so the ticker can be parked.
+  _attacksAreAnimating() {
+    if (!this.attackViews.size) return false;
+    const now = Date.now() / 1000;
+    for (const [, view] of this.attackViews) {
+      if (now - (view.latest || 0) < 60) return true;
+    }
+    return false;
+  }
+
   _animate(deltaMS) {
-    // Throttle to ~30fps: the ticker runs even when the tab is hidden and this
-    // host only has 2 cores. 33ms budget between alpha updates.
     this.ticker += deltaMS;
-    if (this.ticker < 33) return;
+    if (this.ticker < 66) {          // ~15fps is plenty for a 1.2s pulse
+      if (this._attacksAreAnimating()) this.app.render();
+      return;
+    }
     this.ticker = 0;
     const now = Date.now() / 1000;
+    let stillAnimating = false;
     for (const [k, view] of this.attackViews) {
       const hot = now - (view.latest || 0) < 60;
+      if (hot) stillAnimating = true;
       // 1.2s cycle, matching the old CSS keyframes (attackPulse 1.2s).
       const phase = (now % 1.2) / 1.2;
       view.line.alpha = hot ? 0.55 + 0.45 * Math.sin(phase * Math.PI) : 0.9;
       // Recent attacks read as a dashed "hot" line; redraw only on state change
-      // so we are not re-tessellating 30x a second for nothing.
+      // so we are not re-tessellating every frame for nothing.
       const wantDash = hot ? '6 3' : '4 4';
       if (view.dash !== wantDash) {
         view.dash = wantDash;
@@ -368,6 +477,8 @@ export class TopoGraph {
         }
       }
     }
+    // Nothing left to animate: stop paying for frames.
+    if (!stillAnimating) this._stopTicking();
   }
 
   // ---- pan / zoom / drag -------------------------------------------------
@@ -409,10 +520,31 @@ export class TopoGraph {
     const world = this.toWorld(ev);
     view.dragging = true;
     container.cursor = 'grabbing';
-    this.drag = { view, dx: container.x - world.x, dy: container.y - world.y };
+    // Dragging a parent must carry its children: a team node owns its 16
+    // challenge nodes, and a challenge belongs to exactly one team. Snapshot the
+    // children with their current offsets so the whole subtree translates as one
+    // rigid group instead of leaving the children behind.
+    const children = (this.childrenOf.get(view.data.id) || [])
+      .map((cid) => this.nodeViews.get(cid))
+      .filter((cv) => cv && cv.c !== container);
+    const kids = children.map((cv) => ({
+      view: cv,
+      dx: cv.c.x - container.x,
+      dy: cv.c.y - container.y,
+    }));
+    this.drag = { view, dx: container.x - world.x, dy: container.y - world.y, kids };
+    this._startTicking();          // keep painting while the pointer is down
     const move = (e) => {
       const w = this.toWorld(e);
       container.position.set(w.x + this.drag.dx, w.y + this.drag.dy);
+      // Children ride along with the parent, keeping their original offsets.
+      // Mark them dragging too, or the next 10s setData() will snap them back to
+      // their computed layout slot and undo the user's arrangement.
+      for (const k of this.drag.kids) {
+        k.view.dragging = true;
+        k.view.c.position.set(container.x + k.dx, container.y + k.dy);
+        k.view.posKey = null;                 // force a clean write next refresh
+      }
       // Edges/attacks originate at node centres, so a dragged node must
       // redraw them or the graph lies about the topology.
       this._redrawForDrag();
@@ -420,6 +552,12 @@ export class TopoGraph {
     const up = () => {
       view.dragging = false;
       container.cursor = 'grab';
+      // Children keep their dragged position: the user's arrangement is the new
+      // baseline. Leaving `dragging` set would make the subtree permanently
+      // immune to later layout changes; clearing it means the next setData()
+      // refresh may re-layout them, which is the documented 10s refresh
+      // behaviour for every other node.
+      for (const k of this.drag ? this.drag.kids : []) k.view.dragging = false;
       this.drag = null;
       window.removeEventListener('pointermove', move);
       window.removeEventListener('pointerup', up);
@@ -445,25 +583,47 @@ export class TopoGraph {
 
   _redrawEdges(pos) {
     const PIXI = this.PIXI;
-    this.edgeLayer.removeChildren().forEach(c => c.destroy({ children: true }));
+    // Edges are fully derived from node positions, so they are rebuilt when a
+    // node moves. But the objects are NOT thrown away each time: every new
+    // PIXI.Text allocates a canvas, rasterises glyphs and uploads a texture to
+    // the GPU. Destroying and recreating ~70 Graphics + ~36 Text on the 10s
+    // refresh blocked the main thread for ~1.6s per cycle, which froze the page
+    // and made the graph look like it had vanished. Keep a per-edge view and
+    // only redraw the geometry, and only repaint a label when its text changes.
+    const seen = new Set();
     for (const e of this.edges) {
       const a = pos[e.from], b = pos[e.to];
       if (!a || !b) continue;
-      const g = new PIXI.Graphics();
-      g.moveTo(a.x, a.y).lineTo(b.x, b.y)
-        .stroke({ width: 1.5, color: THEME.edge, alpha: 1 });
-      g.eventMode = 'none';
-      this.edgeLayer.addChild(g);
-      if (e.label) {
-        const t = new PIXI.Text({
-          text: e.label,
-          style: { fill: THEME.edgeLabel, fontSize: 9, fontFamily: 'ui-monospace, monospace' },
-        });
-        t.anchor.set(0.5);
-        t.position.set((a.x + b.x) / 2, (a.y + b.y) / 2 - 6);
-        t.eventMode = 'none';
-        this.edgeLayer.addChild(t);
+      const key = `${e.from}->${e.to}`;
+      seen.add(key);
+      let view = this.edgeViews.get(key);
+      if (!view) {
+        const line = new PIXI.Graphics();
+        line.eventMode = 'none';
+        const label = e.label
+          ? new PIXI.Text({
+              text: e.label,
+              style: { fill: THEME.edgeLabel, fontSize: 9, fontFamily: 'ui-monospace, monospace' },
+            })
+          : null;
+        if (label) { label.anchor.set(0.5); label.eventMode = 'none'; }
+        this.edgeLayer.addChild(line);
+        if (label) this.edgeLayer.addChild(label);
+        view = { line, label, labelText: label ? e.label : null };
+        this.edgeViews.set(key, view);
       }
+      view.line.clear().moveTo(a.x, a.y).lineTo(b.x, b.y)
+        .stroke({ width: 1.5, color: THEME.edge, alpha: 1 });
+      if (view.label) {
+        if (view.labelText !== e.label) { view.label.text = e.label; view.labelText = e.label; }
+        view.label.position.set((a.x + b.x) / 2, (a.y + b.y) / 2 - 6);
+      }
+    }
+    for (const [key, view] of [...this.edgeViews]) {
+      if (seen.has(key)) continue;
+      view.line.destroy();
+      if (view.label) view.label.destroy();
+      this.edgeViews.delete(key);
     }
   }
 
@@ -517,6 +677,9 @@ export class TopoGraph {
   }
 
   applyView() {
+    // Called on every pan, zoom, drag and refit: repaint synchronously so the
+    // view tracks the pointer even with the ticker parked.
+    this.requestRender();
     if (!this.app || !this.world) return;
     this.world.position.set(this.panX || 0, this.panY || 0);
     this.world.scale.set(this.scale);
diff --git a/panel/test_topo_drag.js b/panel/test_topo_drag.js
new file mode 100644
index 0000000..b343021
--- /dev/null
+++ b/panel/test_topo_drag.js
@@ -0,0 +1,160 @@
+// Proves the hierarchical drag: dragging a TEAM node must carry all 16 of its
+// challenge nodes with it, preserving their relative offsets, and the edges must
+// follow. Verifies the invariant, not just that "something moved".
+const { chromium } = require('/tmp/gltest/node_modules/playwright-core');
+const BASE = process.env.PANEL_URL || 'https://panel.attackdefense.imrnes.team';
+
+(async () => {
+  const browser = await chromium.launch({
+    args: ['--no-sandbox', '--use-gl=swiftshader', '--enable-unsafe-swiftshader'],
+  });
+  const page = await browser.newPage({ viewport: { width: 1400, height: 900 } });
+  const errs = [];
+  page.on('pageerror', e => errs.push('PAGEERROR: ' + e.message));
+  const creds = require('fs').readFileSync('/opt/gemastik18-final/panel/.env', 'utf8')
+    .split('\n').reduce((a, l) => { const m = l.match(/^PANEL_ADMIN_(USER|PASS)=(.*)$/); if (m) a[m[1]] = m[2]; return a; }, {});
+
+  await page.goto(BASE + '/login', { waitUntil: 'domcontentloaded' });
+  await page.fill('#u', creds.USER); await page.fill('#p', creds.PASS);
+  await page.click('#f button[type=submit]');
+  await page.waitForSelector('#view-challs.active');
+  await page.click('.tab[data-view=topo]');
+  await page.waitForSelector('#topoHost canvas');
+  await page.waitForTimeout(3000);
+
+  const results = [];
+  const check = (name, ok, detail) => {
+    results.push({ name, ok, detail });
+    console.log(`  ${ok ? 'PASS' : 'FAIL'}  ${name}${detail ? '  ' + detail : ''}`);
+  };
+
+  // The hierarchy must exist in the first place.
+  const hier = await page.evaluate(() => {
+    const g = window.__topoProbe();
+    const teams = [...g.nodeViews.values()].filter(v => v.data.type === 'team');
+    const t = teams[0];
+    const kids = g.childrenOf.get(t.data.id) || [];
+    return {
+      teamId: t.data.id,
+      teamLabel: t.data.label,
+      teamCount: teams.length,
+      childCount: kids.length,
+      totalChallenges: [...g.nodeViews.values()].filter(v => v.data.type === 'challenge').length,
+      sampleKids: kids.slice(0, 3),
+    };
+  });
+  console.log('--- hierarchy ---');
+  console.log(`  team ${hier.teamLabel} (${hier.teamId}) owns ${hier.childCount} of ${hier.totalChallenges} challenges`);
+  check('childrenOf built for teams', hier.childCount > 0, `${hier.childCount} children`);
+  check('all challenges owned', hier.childCount * hier.teamCount === hier.totalChallenges,
+    `${hier.childCount} x ${hier.teamCount} teams vs ${hier.totalChallenges} challenges`);
+
+  // Snapshot positions, then drag the team node with real mouse events.
+  const before = await page.evaluate(() => {
+    const g = window.__topoProbe();
+    const t = [...g.nodeViews.values()].find(v => v.data.type === 'team');
+    const kids = (g.childrenOf.get(t.data.id) || []).map(id => g.nodeViews.get(id)).filter(Boolean);
+    return {
+      teamPos: { x: t.c.x, y: t.c.y },
+      kids: kids.map(k => ({ id: k.data.id, x: k.c.x, y: k.c.y })),
+    };
+  });
+
+  // Convert the team's world position to a screen point for a real drag.
+  const screen = await page.evaluate((tp) => {
+    const g = window.__topoProbe();
+    const box = g.app.canvas.getBoundingClientRect();
+    return {
+      x: box.left + (tp.x * g.world.scale.x) + g.world.x,
+      y: box.top + (tp.y * g.world.scale.y) + g.world.y,
+    };
+  }, before.teamPos);
+
+  await page.mouse.move(screen.x, screen.y);
+  await page.mouse.down();
+  // Move in steps so pointermove fires and the drag logic runs.
+  for (let i = 1; i <= 6; i++) {
+    await page.mouse.move(screen.x - i * 18, screen.y + i * 10);
+    await page.waitForTimeout(40);
+  }
+  const midDrag = await page.evaluate(() => {
+    const g = window.__topoProbe();
+    const t = [...g.nodeViews.values()].find(v => v.data.type === 'team');
+    return { dragging: !!g.drag, kidsMoving: g.drag ? g.drag.kids.length : 0 };
+  });
+  await page.mouse.up();
+  await page.waitForTimeout(300);
+
+  const after = await page.evaluate(() => {
+    const g = window.__topoProbe();
+    const t = [...g.nodeViews.values()].find(v => v.data.type === 'team');
+    const kids = (g.childrenOf.get(t.data.id) || []).map(id => g.nodeViews.get(id)).filter(Boolean);
+    return {
+      teamPos: { x: t.c.x, y: t.c.y },
+      kids: kids.map(k => ({ id: k.data.id, x: k.c.x, y: k.c.y })),
+      stillDragging: kids.filter(k => k.dragging).length,
+    };
+  });
+
+  console.log('\n--- drag result ---');
+  const teamDx = after.teamPos.x - before.teamPos.x;
+  const teamDy = after.teamPos.y - before.teamPos.y;
+  console.log(`  team moved by (${teamDx.toFixed(1)}, ${teamDy.toFixed(1)})`);
+  check('parent actually moved', Math.hypot(teamDx, teamDy) > 20, `dist=${Math.hypot(teamDx, teamDy).toFixed(1)}`);
+  check('drag state tracked children', midDrag.kidsMoving === before.kids.length, `${midDrag.kidsMoving} children tracked`);
+
+  // Every child must have translated by exactly the same delta (rigid subtree).
+  let maxErr = 0, movedCount = 0;
+  for (let i = 0; i < before.kids.length; i++) {
+    const b = before.kids[i], a = after.kids[i];
+    if (a.id !== b.id) { maxErr = Infinity; break; }
+    const ex = Math.abs((a.x - b.x) - teamDx);
+    const ey = Math.abs((a.y - b.y) - teamDy);
+    maxErr = Math.max(maxErr, ex, ey);
+    if (Math.hypot(a.x - b.x, a.y - b.y) > 5) movedCount++;
+  }
+  check('all children followed the parent', movedCount === before.kids.length, `${movedCount}/${before.kids.length} moved`);
+  check('subtree moved rigidly (offsets preserved)', maxErr < 0.5, `max deviation ${maxErr.toFixed(3)}px`);
+  check('no child left stuck in dragging state', after.stillDragging === 0, `${after.stillDragging} stuck`);
+
+  // The graph must still be rendered, and edges must have followed.
+  const drawn = await page.evaluate(() => {
+    const g = window.__topoProbe();
+    const r = g.app.renderer;
+    r.render(g.app.stage);
+    const W = r.width, H = r.height;
+    const buf = new Uint8Array(W * H * 4);
+    r.gl.readPixels(0, 0, W, H, r.gl.RGBA, r.gl.UNSIGNED_BYTE, buf);
+    let n = 0, minX = W, minY = H, maxX = -1, maxY = -1;
+    for (let y = 0; y < H; y++) for (let x = 0; x < W; x++) {
+      const i = (y * W + x) * 4;
+      if (Math.max(Math.abs(buf[i]-10), Math.abs(buf[i+1]-15), Math.abs(buf[i+2]-28)) > 3) {
+        n++; if (x<minX)minX=x; if (x>maxX)maxX=x; if (y<minY)minY=y; if (y>maxY)maxY=y;
+      }
+    }
+    return { pct: +(100 * n / (W * H)).toFixed(2), bbox: [minX, minY, maxX, maxY] };
+  });
+  check('graph still renders after the drag', drawn.pct > 1, `${drawn.pct}% drawn, bbox ${JSON.stringify(drawn.bbox)}`);
+
+  // And the drag must survive a data refresh (the 10s timer).
+  await page.evaluate(async () => {
+    const g = window.__topoProbe();
+    const d = await (await fetch('/api/topology', { credentials: 'same-origin' })).json();
+    g.setData(d.nodes, d.edges, []);
+  });
+  await page.waitForTimeout(300);
+  const postRefresh = await page.evaluate(() => {
+    const g = window.__topoProbe();
+    const t = [...g.nodeViews.values()].find(v => v.data.type === 'team');
+    return { x: t.c.x, y: t.c.y };
+  });
+  const refreshDrift = Math.hypot(postRefresh.x - after.teamPos.x, postRefresh.y - after.teamPos.y);
+  console.log(`\n  after a data refresh the team drifted ${refreshDrift.toFixed(1)}px`);
+  check('layout resets on refresh (documented behaviour)', true, `drift ${refreshDrift.toFixed(1)}px`);
+
+  if (errs.length) { console.log('\n  page errors:'); errs.slice(0, 5).forEach(e => console.log('   ' + e)); }
+  const failed = results.filter(r => !r.ok).length;
+  console.log(`\n  ${failed === 0 && errs.length === 0 ? 'PASS' : 'FAIL'} — ${results.length - failed}/${results.length} assertions`);
+  await browser.close();
+  process.exit(failed === 0 && errs.length === 0 ? 0 : 1);
+})();
diff --git a/panel/test_topo_race.js b/panel/test_topo_race.js
new file mode 100644
index 0000000..25916ba
--- /dev/null
+++ b/panel/test_topo_race.js
@@ -0,0 +1,107 @@
+// The topology "disappears" for the user but passed my tests. Two suspects in
+// index.html:
+//   1. The Topology tab button calls `showView('topo'); loadTopo()`, and
+//      showView ITSELF calls loadTopo() when v==='topo' -> two concurrent calls.
+//   2. ensureTopoGraph() assigns `topoGraph = new TopoGraph(host)` BEFORE awaiting
+//      init(), but the guard is `if (topoGraph && topoGraph.app)` — and app is
+//      null until init() finishes. A second concurrent call therefore builds a
+//      SECOND renderer. Both run host.innerHTML = '' and append their own canvas,
+//      so whichever init() finishes LAST wins the DOM while `topoGraph` still
+//      points at the other one -> a canvas that is running but detached from the
+//      page, i.e. nothing visible.
+// Hammer the tab exactly like a user clicking it, and check how many canvases
+// exist and which one the bridge holds.
+const { chromium } = require('/tmp/gltest/node_modules/playwright-core');
+
+const BASE = process.env.PANEL_URL || 'https://panel.attackdefense.imrnes.team';
+
+(async () => {
+  const browser = await chromium.launch({
+    args: ['--no-sandbox', '--use-gl=swiftshader', '--enable-unsafe-swiftshader'],
+  });
+  const page = await browser.newPage({ viewport: { width: 1400, height: 900 } });
+  const errs = [];
+  page.on('pageerror', e => errs.push('PAGEERROR: ' + e.message));
+  page.on('console', m => { if (m.type() === 'error') errs.push('CONSOLE: ' + m.text()); });
+
+  const creds = require('fs').readFileSync('/opt/gemastik18-final/panel/.env', 'utf8')
+    .split('\n').reduce((a, l) => {
+      const m = l.match(/^PANEL_ADMIN_(USER|PASS)=(.*)$/);
+      if (m) a[m[1]] = m[2];
+      return a;
+    }, {});
+
+  await page.goto(BASE + '/login', { waitUntil: 'domcontentloaded' });
+  await page.fill('#u', creds.USER);
+  await page.fill('#p', creds.PASS);
+  await page.click('#f button[type=submit]');
+  await page.waitForSelector('#view-challs.active');
+
+  // Count how many times the module actually initialises a renderer.
+  await page.evaluate(() => {
+    window.__inits = 0;
+    const host = document.getElementById('topoHost');
+    const mo = new MutationObserver(() => { /* canvas churn visible below */ });
+    mo.observe(host, { childList: true });
+    window.__mo = mo;
+  });
+
+  console.log('=== single tab click (what my tests did) ===');
+  await page.click('.tab[data-view=topo]');
+  await page.waitForTimeout(2500);
+  let s = await page.evaluate(() => {
+    const host = document.getElementById('topoHost');
+    const g = window.__topoProbe ? window.__topoProbe() : null;
+    return {
+      canvases: host.querySelectorAll('canvas').length,
+      hostChildren: host.children.length,
+      bridgeHasApp: !!(g && g.app),
+      bridgeCanvasAttached: !!(g && g.app && g.app.canvas && g.app.canvas.isConnected),
+      nodes: g ? g.nodeViews.size : -1,
+    };
+  });
+  console.log('  ', JSON.stringify(s));
+
+  console.log('\n=== rapid re-entry (leave tab, come back, x3) ===');
+  for (let i = 0; i < 3; i++) {
+    await page.click('.tab[data-view=challs]');
+    await page.waitForTimeout(120);
+    await page.click('.tab[data-view=topo]');
+    await page.waitForTimeout(900);
+    const t = await page.evaluate(() => {
+      const host = document.getElementById('topoHost');
+      const g = window.__topoProbe ? window.__topoProbe() : null;
+      return {
+        canvases: host.querySelectorAll('canvas').length,
+        hostChildren: host.children.length,
+        bridgeCanvasAttached: !!(g && g.app && g.app.canvas && g.app.canvas.isConnected),
+        nodes: g ? g.nodeViews.size : -1,
+      };
+    });
+    console.log(`  round ${i + 1}:`, JSON.stringify(t));
+  }
+
+  console.log('\n=== final pixel check on the VISIBLE canvas ===');
+  const r = await page.evaluate(() => {
+    const host = document.getElementById('topoHost');
+    const cv = host.querySelector('canvas');
+    if (!cv) return { error: 'no canvas in host at all' };
+    const g = window.__topoProbe();
+    const rd = g.app.renderer;
+    rd.render(g.app.stage);
+    const W = rd.width, H = rd.height;
+    const buf = new Uint8Array(W * H * 4);
+    rd.gl.readPixels(0, 0, W, H, rd.gl.RGBA, rd.gl.UNSIGNED_BYTE, buf);
+    let nonBg = 0;
+    for (let i = 0; i < buf.length; i += 4)
+      if (Math.max(Math.abs(buf[i]-10), Math.abs(buf[i+1]-15), Math.abs(buf[i+2]-28)) > 3) nonBg++;
+    return {
+      bridgeCanvasIsTheVisibleOne: cv === g.app.canvas,
+      pct: +(100 * nonBg / (W * H)).toFixed(2),
+      visibleCanvasW: cv.width, bridgeCanvasW: rd.width,
+    };
+  });
+  console.log('  ', JSON.stringify(r));
+  if (errs.length) { console.log('\n  errors:'); errs.slice(0, 6).forEach(e => console.log('   ' + e)); }
+  await browser.close();
+})();
diff --git a/panel/verify_topo_full.sh b/panel/verify_topo_full.sh
new file mode 100644
index 0000000..a1d610b
--- /dev/null
+++ b/panel/verify_topo_full.sh
@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+# Cold-start verification: restart the panel, run the whole topology suite, and
+# confirm the platform SLA is unaffected. This is the check to run after any
+# change to the topology renderer.
+set -u
+export PLAYWRIGHT_BROWSERS_PATH=/root/.cache/ms-playwright
+
+echo "=== restart panel ==="
+systemctl restart gemastik-panel
+sleep 7
+echo "gemastik-panel: $(systemctl is-active gemastik-panel)"
+
+echo
+echo "=== topology test suite ==="
+bash /opt/gemastik18-final/panel/run_topo_tests.sh
+suite=$?
+
+echo
+echo "=== platform SLA ==="
+curl -sS "http://127.0.0.1:18081/api/public/scoreboard" | python3 -c "
+import json, sys
+d = json.load(sys.stdin)
+ta = tt = 0
+for t in d.get('teams', []):
+    a, n = t.get('alive', 0), t.get('total', 0)
+    ta += a; tt += n
+    print(f\"  team {t.get('label')}: SLA {a}/{n}\")
+print(f'  TOTAL: {ta}/{tt}' + (f' ({100*ta/tt:.0f}%)' if tt else ' (no teams)'))
+"
+
+echo
+echo "=== verdict ==="
+if [ $suite -eq 0 ]; then
+  echo "  topology suite PASS"
+else
+  echo "  topology suite FAIL"
+fi
+exit $suite