From 44de8deeeb28ea5a2681a0abc6c9b769646ccafd Mon Sep 17 00:00:00 2001
From: Michael Pilosov <consistentbayes@gmail.com>
Date: Wed, 22 Apr 2026 16:17:01 -0600
Subject: [PATCH] viz: extract N-panel-agnostic module; homepage modal reuses
 it for single-run view
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- panel-grid.js (new): exports mountPanels({host, controls, stems}) → {destroy}.
  Moved createPanel + shared control wiring + linked-hover + pad-to-match
  time mapping out of compare.js. Stem-count-agnostic; works for 1, 2, or N.
- Panel DOM is cloned from <template id=compare-panel-tpl> on each page.
- compare.js is now a ~10-line shim: parse ?a=&b=, call mountPanels.
- Per-panel color is viridis-sampled by index/N (middle viridis for N=1,
  ends-of-palette for N=2, linear lerp for N≤8, cycle at N≥9). Set as
  --panel-color on the panel element; CSS reads it for tag/time-seg.
- Homepage <dialog id=run-modal> + run-modal.js hijack the 'embedding' link
  (plain click → modal; meta/ctrl/middle-click still opens plotly HTML).
  Dialog close disposes every panel's renderer/geometry/material.
- .compare-grid → repeat(auto-fit, minmax(360px, 1fr)) handles N=1..many,
  replaces the <900px one-column media rule.
- Runs list: relabel Prefect's 'Late' state as 'Queued' — more honest
  description of what the runner is doing at the concurrency cap.
---
 app/web/main.py                |   5 +
 app/web/static/compare.js      | 734 +-------------------------------
 app/web/static/panel-grid.js   | 756 +++++++++++++++++++++++++++++++++
 app/web/static/run-modal.js    |  69 +++
 app/web/static/style.css       |  72 +++-
 app/web/templates/_runs.html   |   3 +-
 app/web/templates/compare.html |  56 +--
 app/web/templates/index.html   |  67 ++-
 8 files changed, 984 insertions(+), 778 deletions(-)
 create mode 100644 app/web/static/panel-grid.js
 create mode 100644 app/web/static/run-modal.js

diff --git a/app/web/main.py b/app/web/main.py
index 77d38d5..e04b25e 100644
--- a/app/web/main.py
+++ b/app/web/main.py
@@ -590,6 +590,11 @@ def _run_view(run: Dict[str, Any]) -> Dict[str, Any]:
     rid = run.get("id", "")
     state_type = (run.get("state_type") or "PENDING").upper()
     state_name = run.get("state_name") or state_type.title()
+    # Prefect labels a scheduled run that's past its start time "Late". The
+    # runner is simply busy / awaiting its turn at the concurrency cap — show
+    # "Queued" instead, which is the honest description of the state.
+    if state_name == "Late":
+        state_name = "Queued"
     start = run.get("start_time") or run.get("expected_start_time") or run.get("created")
     params = run.get("parameters") or {}
     # estimated_run_time recomputes server-side (ticks up while RUNNING);
diff --git a/app/web/static/compare.js b/app/web/static/compare.js
index b5fdbdf..ceb1814 100644
--- a/app/web/static/compare.js
+++ b/app/web/static/compare.js
@@ -1,733 +1,11 @@
-// compare.js — side-by-side animated scatter for two embedding runs.
-//
-// Reads ?a=<stemA>&b=<stemB> from the URL, fetches /api/runs/<stem>/frames.json
-// for each, and renders them into two linked three.js panels with a shared
-// play/scrub/speed control strip. Linked hover: cursor on a point in one
-// panel highlights the same point_id in the other.
+// compare.js — thin shim that parses ?a=&b= and hands off to panel-grid.js.
 
-import * as THREE from 'three';
-
-// -------- URL / DOM wiring ------------------------------------------------
+import { mountPanels } from './panel-grid.js?v=1';
 
 const params = new URLSearchParams(window.location.search);
-const STEM_A = params.get('a') || '';
-const STEM_B = params.get('b') || '';
+const stems = [params.get('a') || '', params.get('b') || ''].filter(Boolean);
 
-const layout = document.getElementById('compare-layout');
-const panelElA = layout.querySelector('.compare-panel[data-slot="a"]');
-const panelElB = layout.querySelector('.compare-panel[data-slot="b"]');
+const host = document.getElementById('panel-host');
+const controls = document.getElementById('compare-controls');
 
-const playBtn = document.getElementById('cc-play');
-const scrub = document.getElementById('cc-scrub');
-const speedSel = document.getElementById('cc-speed');
-const syncSel = document.getElementById('cc-sync');
-const motionSel = document.getElementById('cc-motion');
-const colorSel = document.getElementById('cc-color');
-const timeAEl = document.getElementById('cc-time').querySelector('[data-role="time-a"]');
-const timeBEl = document.getElementById('cc-time').querySelector('[data-role="time-b"]');
-
-// -------- small helpers ---------------------------------------------------
-
-// Build a soft-edged circular sprite for THREE.Points. A plain texture with
-// radial alpha gives anti-aliased round dots without fragment-shader work.
-function makeDiskTexture(size = 64) {
-  const c = document.createElement('canvas');
-  c.width = c.height = size;
-  const g = c.getContext('2d');
-  const r = size / 2;
-  const grd = g.createRadialGradient(r, r, 0, r, r, r);
-  grd.addColorStop(0.0, 'rgba(255,255,255,1)');
-  grd.addColorStop(0.55, 'rgba(255,255,255,1)');
-  grd.addColorStop(0.85, 'rgba(255,255,255,0.35)');
-  grd.addColorStop(1.0, 'rgba(255,255,255,0)');
-  g.fillStyle = grd;
-  g.fillRect(0, 0, size, size);
-  const tex = new THREE.CanvasTexture(c);
-  tex.needsUpdate = true;
-  return tex;
-}
-
-const DISK_TEX = makeDiskTexture();
-
-// Continuous ramp (blue → orange), matching dataset-picker.js exactly.
-function rampContinuous(t, out) {
-  const hue = (1 - t) * 215 + t * 28;
-  const sat = 0.62;
-  const lit = 0.50 + (t - 0.5) * 0.08;
-  return (out || new THREE.Color()).setHSL(hue / 360, sat, lit);
-}
-
-// 8-color categorical palette — same hex list as dataset-picker.js.
-const CATEGORICAL_HEX = [
-  '#1f4e5f', '#c97b3f', '#8b5a9f', '#5a8560',
-  '#c74a5e', '#6b7d8f', '#b89f51', '#4a6fa5',
-];
-const CATEGORICAL = CATEGORICAL_HEX.map(h => new THREE.Color(h));
-
-// Precompute per-point RGB, indexed by position in data.point_ids.
-// If the server attached labels + label_kind, color by that (ramp for
-// continuous, palette for categorical) to match the dataset picker. Points
-// with null labels (jitter-added, id >= num_points) stay (0,0,0) = black.
-// Falls back to a frame-0-present ordinal ramp when no labels are present.
-function buildIdColorsRGB(data) {
-  const n = data.point_ids.length;
-  const rgb = new Float32Array(n * 3);
-  const labels = data.labels || [];
-  const kind = data.label_kind || null;
-  const hasRealLabels = kind && labels.some(v => v != null && v !== '');
-
-  if (hasRealLabels) {
-    const tmp = new THREE.Color();
-    if (kind === 'categorical') {
-      for (let i = 0; i < n; i++) {
-        const v = labels[i];
-        if (v == null) continue;
-        const c = CATEGORICAL[((v | 0) % CATEGORICAL.length + CATEGORICAL.length) % CATEGORICAL.length];
-        rgb[i * 3 + 0] = c.r;
-        rgb[i * 3 + 1] = c.g;
-        rgb[i * 3 + 2] = c.b;
-      }
-    } else {
-      let lo = Infinity, hi = -Infinity;
-      for (const v of labels) { if (v == null) continue; if (v < lo) lo = v; if (v > hi) hi = v; }
-      const range = (hi - lo) || 1;
-      for (let i = 0; i < n; i++) {
-        const v = labels[i];
-        if (v == null) continue;
-        rampContinuous((v - lo) / range, tmp);
-        rgb[i * 3 + 0] = tmp.r;
-        rgb[i * 3 + 1] = tmp.g;
-        rgb[i * 3 + 2] = tmp.b;
-      }
-    }
-    return rgb;
-  }
-
-  // Fallback: rainbow-by-ordinal over frame-0-present points.
-  const frame0 = data.frames[0];
-  if (!frame0) return rgb;
-  const originalPositions = [];
-  for (let i = 0; i < n; i++) {
-    if (frame0.x[i] != null && frame0.y[i] != null
-        && !Number.isNaN(frame0.x[i]) && !Number.isNaN(frame0.y[i])) {
-      originalPositions.push(i);
-    }
-  }
-  originalPositions.sort((a, b) => data.point_ids[a] - data.point_ids[b]);
-  const nOrig = originalPositions.length;
-  const tmp = new THREE.Color();
-  for (let k = 0; k < nOrig; k++) {
-    const t = nOrig > 1 ? k / (nOrig - 1) : 0.5;
-    rampContinuous(t, tmp);
-    const idx = originalPositions[k];
-    rgb[idx * 3 + 0] = tmp.r;
-    rgb[idx * 3 + 1] = tmp.g;
-    rgb[idx * 3 + 2] = tmp.b;
-  }
-  return rgb;
-}
-
-function readVar(name, fallback) {
-  const v = getComputedStyle(document.documentElement).getPropertyValue(name).trim();
-  return v || fallback;
-}
-
-function readPanelBg(el) {
-  const v = getComputedStyle(el).getPropertyValue('--picker-panel').trim();
-  return v || readVar('--panel', '#ffffff');
-}
-
-// Panel accent colors keyed by slot. Resolved from CSS vars so they flip
-// with the theme via 'themechange'.
-function panelAccent(slot) {
-  return slot === 'a' ? readVar('--accent', '#1f4e5f') : readVar('--warm', '#a77a2c');
-}
-
-function highlightColor() {
-  return readVar('--alarm', '#8a3a2a');
-}
-
-// -------- Panel factory ---------------------------------------------------
-
-// Returns { setFrame, setBounds, setHighlight, onHover, resize, dispose, state }
-function createPanel({ slotId, panelEl, data }) {
-  const canvasEl = panelEl.querySelector('[data-role="canvas"]');
-  const statusEl = panelEl.querySelector('[data-role="status"]');
-
-  const scene = new THREE.Scene();
-  scene.background = new THREE.Color(readPanelBg(panelEl));
-
-  const camera = new THREE.OrthographicCamera(-1, 1, 1, -1, -10, 10);
-  const renderer = new THREE.WebGLRenderer({ antialias: true, alpha: false });
-  renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2));
-  canvasEl.appendChild(renderer.domElement);
-
-  // Pre-allocate a buffer sized for num_points. Each frame we repack the
-  // non-null points into the prefix and call setDrawRange(0, count).
-  const maxN = data.point_ids.length;
-  const positions = new Float32Array(maxN * 3);
-  const colors = new Float32Array(maxN * 3);
-  const ids = new Int32Array(maxN); // packed point_id per drawn vertex
-  const idColorRGB = buildIdColorsRGB(data);
-
-  const geo = new THREE.BufferGeometry();
-  geo.setAttribute('position', new THREE.BufferAttribute(positions, 3));
-  geo.setAttribute('color', new THREE.BufferAttribute(colors, 3));
-  geo.setDrawRange(0, 0);
-
-  const matMono = new THREE.PointsMaterial({
-    size: 6.0,
-    sizeAttenuation: false,
-    map: DISK_TEX,
-    transparent: true,
-    alphaTest: 0.2,
-    depthWrite: false,
-    color: new THREE.Color(panelAccent(slotId)),
-  });
-  const matRainbow = new THREE.PointsMaterial({
-    size: 6.0,
-    sizeAttenuation: false,
-    map: DISK_TEX,
-    // Opaque + alpha cutoff rather than alpha blending: with a ramp, many
-    // overlapping translucent points average out to the middle of the ramp
-    // (blue + orange → green), washing out the whole cloud. Hard edges keep
-    // each point's true color visible.
-    transparent: false,
-    alphaTest: 0.5,
-    vertexColors: true,
-  });
-  let mat = matMono;
-  const points = new THREE.Points(geo, mat);
-  scene.add(points);
-
-  // Highlight overlay — a second 1-vertex Points object drawn on top.
-  const hiPos = new Float32Array(3);
-  const hiGeo = new THREE.BufferGeometry();
-  hiGeo.setAttribute('position', new THREE.BufferAttribute(hiPos, 3));
-  hiGeo.setDrawRange(0, 0);
-  const hiMat = new THREE.PointsMaterial({
-    size: 14.0,
-    sizeAttenuation: false,
-    map: DISK_TEX,
-    transparent: true,
-    alphaTest: 0.05,
-    depthWrite: false,
-    color: new THREE.Color(highlightColor()),
-    opacity: 0.9,
-  });
-  const hiPoints = new THREE.Points(hiGeo, hiMat);
-  // Ensure highlight renders above base points
-  hiPoints.renderOrder = 1;
-  scene.add(hiPoints);
-
-  // ---- current-frame packed state (kept in closure for hover picking) ----
-  // packedX/packedY/packedId of length = current draw count.
-  let packedN = 0;
-  const packedX = new Float32Array(maxN);
-  const packedY = new Float32Array(maxN);
-  const packedId = new Int32Array(maxN);
-
-  // Camera frame rectangle (world coords) currently applied.
-  const camRect = { xmin: -1, xmax: 1, ymin: -1, ymax: 1 };
-
-  function applyCamRect(rect) {
-    const pad = 0.05;
-    const dx = rect.xmax - rect.xmin || 1;
-    const dy = rect.ymax - rect.ymin || 1;
-    const cx = (rect.xmin + rect.xmax) / 2;
-    const cy = (rect.ymin + rect.ymax) / 2;
-    const rx = dx * (0.5 + pad);
-    const ry = dy * (0.5 + pad);
-    // Fit-to-larger-axis so points never get squashed when the panel aspect
-    // doesn't match the bounds aspect. We compute the viewport aspect here
-    // so the ortho frustum covers the data and then some.
-    const rect2 = canvasEl.getBoundingClientRect();
-    const vw = Math.max(1, rect2.width);
-    const vh = Math.max(1, rect2.height);
-    const aspect = vw / vh;
-    const dataAspect = (rx * 2) / (ry * 2);
-    let halfW, halfH;
-    if (aspect > dataAspect) {
-      // viewport wider than data: expand X to fit
-      halfH = ry;
-      halfW = ry * aspect;
-    } else {
-      halfW = rx;
-      halfH = rx / aspect;
-    }
-    camera.left = cx - halfW;
-    camera.right = cx + halfW;
-    camera.top = cy + halfH;
-    camera.bottom = cy - halfH;
-    camera.updateProjectionMatrix();
-    camRect.xmin = rect.xmin;
-    camRect.xmax = rect.xmax;
-    camRect.ymin = rect.ymin;
-    camRect.ymax = rect.ymax;
-  }
-
-  function resize() {
-    const rect = canvasEl.getBoundingClientRect();
-    const w = Math.max(1, Math.floor(rect.width));
-    const h = Math.max(1, Math.floor(rect.height));
-    renderer.setSize(w, h, false);
-    // Re-apply the current cam rect so the aspect fit recomputes.
-    applyCamRect(camRect);
-  }
-
-  function setBounds(b) {
-    applyCamRect({ xmin: b.x[0], xmax: b.x[1], ymin: b.y[0], ymax: b.y[1] });
-  }
-
-  function applyColorsFromTheme() {
-    matMono.color.set(panelAccent(slotId));
-    hiMat.color.set(highlightColor());
-    scene.background = new THREE.Color(readPanelBg(panelEl));
-  }
-
-  function setColorMode(mode) {
-    const next = mode === 'mono' ? matMono : matRainbow;
-    if (points.material !== next) {
-      points.material = next;
-      mat = next;
-    }
-  }
-
-  // Copy the precomputed per-id RGB into the packed position `j`.
-  function writePackedColor(j, i) {
-    colors[j * 3 + 0] = idColorRGB[i * 3 + 0];
-    colors[j * 3 + 1] = idColorRGB[i * 3 + 1];
-    colors[j * 3 + 2] = idColorRGB[i * 3 + 2];
-  }
-
-  // Pack frame `f` into the geometry buffer, skipping null x/y.
-  function setFrame(f) {
-    const frame = data.frames[f];
-    if (!frame) return;
-    const xs = frame.x, ys = frame.y;
-    const ptIds = data.point_ids;
-    let j = 0;
-    for (let i = 0; i < xs.length; i++) {
-      const x = xs[i], y = ys[i];
-      if (x === null || y === null || x === undefined || y === undefined
-          || Number.isNaN(x) || Number.isNaN(y)) continue;
-      positions[j * 3 + 0] = x;
-      positions[j * 3 + 1] = y;
-      positions[j * 3 + 2] = 0;
-      writePackedColor(j, i);
-      packedX[j] = x;
-      packedY[j] = y;
-      packedId[j] = ptIds[i];
-      j++;
-    }
-    packedN = j;
-    geo.attributes.position.needsUpdate = true;
-    geo.attributes.color.needsUpdate = true;
-    geo.setDrawRange(0, packedN);
-    applyHighlightForCurrentFrame();
-  }
-
-  // Pack an interpolated frame. uLocal is a continuous index in [0, T-1].
-  // Points missing in either adjacent frame are skipped for the duration of
-  // that transition (no connect-back to the last-known position).
-  function setFrameInterpolated(uLocal) {
-    const T = data.frames.length;
-    if (T === 0) return;
-    if (uLocal <= 0)        return setFrame(0);
-    if (uLocal >= T - 1)    return setFrame(T - 1);
-    const f0 = Math.floor(uLocal);
-    const f1 = f0 + 1;
-    const t  = uLocal - f0;
-    const fr0 = data.frames[f0], fr1 = data.frames[f1];
-    const x0 = fr0.x, y0 = fr0.y, x1 = fr1.x, y1 = fr1.y;
-    const ptIds = data.point_ids;
-    let j = 0;
-    for (let i = 0; i < x0.length; i++) {
-      const a = x0[i], b = x1[i], c = y0[i], d = y1[i];
-      if (a === null || a === undefined || Number.isNaN(a)
-          || b === null || b === undefined || Number.isNaN(b)
-          || c === null || c === undefined || Number.isNaN(c)
-          || d === null || d === undefined || Number.isNaN(d)) continue;
-      const xi = a + (b - a) * t;
-      const yi = c + (d - c) * t;
-      positions[j * 3 + 0] = xi;
-      positions[j * 3 + 1] = yi;
-      positions[j * 3 + 2] = 0;
-      writePackedColor(j, i);
-      packedX[j] = xi;
-      packedY[j] = yi;
-      packedId[j] = ptIds[i];
-      j++;
-    }
-    packedN = j;
-    geo.attributes.position.needsUpdate = true;
-    geo.attributes.color.needsUpdate = true;
-    geo.setDrawRange(0, packedN);
-    applyHighlightForCurrentFrame();
-  }
-
-  // ---- highlight by point_id ---------------------------------------------
-  let currentHighlightId = -1;
-
-  function applyHighlightForCurrentFrame() {
-    if (currentHighlightId < 0) {
-      hiGeo.setDrawRange(0, 0);
-      return;
-    }
-    // Linear scan — packedN <= 5000 and this only runs on hover.
-    for (let i = 0; i < packedN; i++) {
-      if (packedId[i] === currentHighlightId) {
-        hiPos[0] = packedX[i];
-        hiPos[1] = packedY[i];
-        hiPos[2] = 0.01;
-        hiGeo.attributes.position.needsUpdate = true;
-        hiGeo.setDrawRange(0, 1);
-        return;
-      }
-    }
-    // Not present this frame.
-    hiGeo.setDrawRange(0, 0);
-  }
-
-  function setHighlight(pointId) {
-    currentHighlightId = (pointId === null || pointId === undefined) ? -1 : pointId;
-    applyHighlightForCurrentFrame();
-  }
-
-  // Convert clientX/Y to world coords (ortho, no rotation).
-  function clientToWorld(clientX, clientY) {
-    const rect = canvasEl.getBoundingClientRect();
-    const u = (clientX - rect.left) / Math.max(1, rect.width);
-    const v = (clientY - rect.top) / Math.max(1, rect.height);
-    const wx = camera.left + u * (camera.right - camera.left);
-    const wy = camera.top - v * (camera.top - camera.bottom);
-    return { wx, wy };
-  }
-
-  // Nearest-point pick with a screen-space radius cap. Returns point_id or -1.
-  function pickAt(clientX, clientY) {
-    if (packedN === 0) return -1;
-    const { wx, wy } = clientToWorld(clientX, clientY);
-    // Screen-pixel radius -> world radius
-    const rect = canvasEl.getBoundingClientRect();
-    const worldPerPx = (camera.right - camera.left) / Math.max(1, rect.width);
-    const pickPx = 14;
-    const maxR = pickPx * worldPerPx;
-    const maxR2 = maxR * maxR;
-    let bestI = -1;
-    let bestD2 = Infinity;
-    for (let i = 0; i < packedN; i++) {
-      const dx = packedX[i] - wx;
-      const dy = packedY[i] - wy;
-      const d2 = dx * dx + dy * dy;
-      if (d2 < bestD2 && d2 < maxR2) {
-        bestD2 = d2;
-        bestI = i;
-      }
-    }
-    return bestI < 0 ? -1 : packedId[bestI];
-  }
-
-  function render() {
-    renderer.render(scene, camera);
-  }
-
-  function dispose() {
-    geo.dispose();
-    hiGeo.dispose();
-    matMono.dispose();
-    matRainbow.dispose();
-    hiMat.dispose();
-    renderer.dispose();
-    if (renderer.domElement.parentNode) {
-      renderer.domElement.parentNode.removeChild(renderer.domElement);
-    }
-  }
-
-  // Hide the status overlay once we have data.
-  statusEl.style.display = 'none';
-
-  return {
-    slotId,
-    canvasEl,
-    panelEl,
-    data,
-    setFrame,
-    setFrameInterpolated,
-    setColorMode,
-    setBounds,
-    setHighlight,
-    resize,
-    render,
-    pickAt,
-    applyColorsFromTheme,
-    dispose,
-    get packedN() { return packedN; },
-    get camRect() { return camRect; },
-    applyCamRect,
-  };
-}
-
-// -------- error rendering -------------------------------------------------
-
-function renderError(panelEl, stem, msg) {
-  const statusEl = panelEl.querySelector('[data-role="status"]');
-  statusEl.style.display = '';
-  statusEl.classList.add('is-error');
-  statusEl.textContent = `could not load ${stem}: ${msg}`;
-  // Keep header readable
-  panelEl.querySelector('[data-role="embedder"]').textContent = '—';
-  panelEl.querySelector('[data-role="generator"]').textContent = '—';
-  panelEl.querySelector('[data-role="params"]').textContent = '(error)';
-}
-
-const PARAM_FIELDS = [
-  { key: 'num_points',    prefix: 'N' },
-  { key: 'num_timesteps', prefix: 'T' },
-  { key: 'jitter_scale',  prefix: 'J' },
-  { key: 'seed',          prefix: 's' },
-];
-
-function renderHeader(panelEl, data) {
-  const m = data.meta || {};
-  panelEl.querySelector('[data-role="embedder"]').textContent = m.embedder || '—';
-  panelEl.querySelector('[data-role="generator"]').textContent = m.generator || '—';
-  const host = panelEl.querySelector('[data-role="params"]');
-  host.textContent = '';
-  PARAM_FIELDS.forEach(({ key, prefix }, i) => {
-    if (i > 0) host.appendChild(document.createTextNode(' / '));
-    const span = document.createElement('span');
-    span.className = 'param';
-    span.dataset.key = key;
-    span.textContent = `${prefix}${m[key] ?? '?'}`;
-    host.appendChild(span);
-  });
-}
-
-// Toggle .diff on header spans where the two panels disagree.
-function markParamDiffs(metaA, metaB) {
-  if (!metaA || !metaB) return;
-  for (const { key } of PARAM_FIELDS) {
-    const differs = metaA[key] !== metaB[key];
-    for (const panelEl of [panelElA, panelElB]) {
-      const span = panelEl.querySelector(`[data-role="params"] .param[data-key="${key}"]`);
-      if (span) span.classList.toggle('diff', differs);
-    }
-  }
-  for (const role of ['embedder', 'generator']) {
-    const differs = metaA[role] !== metaB[role];
-    for (const panelEl of [panelElA, panelElB]) {
-      const span = panelEl.querySelector(`[data-role="${role}"]`);
-      if (span) span.classList.toggle('diff', differs);
-    }
-  }
-}
-
-// -------- main ------------------------------------------------------------
-
-async function fetchFrames(stem) {
-  const res = await fetch(`/api/runs/${encodeURIComponent(stem)}/frames.json`, { cache: 'no-store' });
-  if (!res.ok) {
-    throw new Error(`${res.status} ${res.statusText}`);
-  }
-  return res.json();
-}
-
-async function main() {
-  if (!STEM_A || !STEM_B) {
-    renderError(panelElA, STEM_A || '(missing)', 'no stem in ?a=');
-    renderError(panelElB, STEM_B || '(missing)', 'no stem in ?b=');
-    return;
-  }
-
-  // Fetch in parallel; each panel's failure is independent.
-  const [resA, resB] = await Promise.allSettled([
-    fetchFrames(STEM_A),
-    fetchFrames(STEM_B),
-  ]);
-
-  const panels = { a: null, b: null };
-
-  if (resA.status === 'fulfilled') {
-    renderHeader(panelElA, resA.value);
-    panels.a = createPanel({ slotId: 'a', panelEl: panelElA, data: resA.value });
-  } else {
-    renderError(panelElA, STEM_A, resA.reason?.message || String(resA.reason));
-  }
-  if (resB.status === 'fulfilled') {
-    renderHeader(panelElB, resB.value);
-    panels.b = createPanel({ slotId: 'b', panelEl: panelElB, data: resB.value });
-  } else {
-    renderError(panelElB, STEM_B, resB.reason?.message || String(resB.reason));
-  }
-
-  if (panels.a && panels.b) markParamDiffs(panels.a.data.meta, panels.b.data.meta);
-
-  // Nothing loaded — no animation loop to start.
-  if (!panels.a && !panels.b) return;
-
-  // Initial bounds + first frame for each panel.
-  for (const p of Object.values(panels)) {
-    if (!p) continue;
-    p.setBounds(p.data.bounds);
-    p.resize();
-    p.setFrame(0);
-  }
-
-  // ---- time mapping -----------------------------------------------------
-  // Scrubber is 0..1000, mapped to a shared global frame index uGlobal in
-  // [0, maxT-1]. Each panel clamps uGlobal to its own (T-1) — so a shorter
-  // timeline pads its last frame until the longer timeline finishes, and
-  // both panels advance at the same wall-clock tempo.
-  const SCRUB_MAX = 1000;
-
-  function framesOf(p) { return p ? p.data.frames.length : 0; }
-
-  function timeLabelForAtLocal(p, uLocal) {
-    if (!p) return '—';
-    const T = framesOf(p);
-    if (T <= 0) return '—';
-    const idx = Math.max(0, Math.min(T - 1, Math.round(uLocal)));
-    return p.data.times?.[idx] ?? String(idx);
-  }
-
-  function applyU(u) {
-    u = Math.max(0, Math.min(1, u));
-    const smooth = motionSel.value === 'smooth';
-    const tMax = maxT();
-    const uGlobal = u * (tMax - 1);
-    let uLocalA = 0, uLocalB = 0;
-    for (const [slot, p] of Object.entries(panels)) {
-      if (!p) continue;
-      const T = framesOf(p);
-      if (T <= 0) continue;
-      const uLocal = Math.min(uGlobal, T - 1);
-      if (slot === 'a') uLocalA = uLocal; else uLocalB = uLocal;
-      if (smooth) {
-        p.setFrameInterpolated(uLocal);
-      } else {
-        const idx = Math.max(0, Math.min(T - 1, Math.round(uLocal)));
-        p.setFrame(idx);
-      }
-    }
-    timeAEl.textContent = timeLabelForAtLocal(panels.a, uLocalA);
-    timeBEl.textContent = timeLabelForAtLocal(panels.b, uLocalB);
-  }
-
-  // ---- axes sync mode ---------------------------------------------------
-  function applySync() {
-    const mode = syncSel.value;
-    if (mode === 'locked' && panels.a && panels.b) {
-      const ba = panels.a.data.bounds, bb = panels.b.data.bounds;
-      const union = {
-        x: [Math.min(ba.x[0], bb.x[0]), Math.max(ba.x[1], bb.x[1])],
-        y: [Math.min(ba.y[0], bb.y[0]), Math.max(ba.y[1], bb.y[1])],
-      };
-      panels.a.setBounds(union);
-      panels.b.setBounds(union);
-    } else {
-      if (panels.a) panels.a.setBounds(panels.a.data.bounds);
-      if (panels.b) panels.b.setBounds(panels.b.data.bounds);
-    }
-  }
-  syncSel.addEventListener('change', applySync);
-  applySync();
-
-  // ---- play loop --------------------------------------------------------
-  // Base step: 400ms per frame at 1x, divided by speed. The loop advances
-  // the scrub by (1 / maxT) per step so both panels traverse their whole
-  // timeline in the same wall-clock duration when T differs.
-  let playing = false;
-  let lastTs = 0;
-  function maxT() {
-    const ta = framesOf(panels.a);
-    const tb = framesOf(panels.b);
-    return Math.max(ta, tb, 2);
-  }
-  function baseMsPerFrame() { return 1600 / parseFloat(speedSel.value || '1'); }
-
-  // u is the authoritative playhead (float in [0, 1]). The scrubber mirrors
-  // it for display; reading u back from the scrubber would quantize to the
-  // scrubber's integer step and stall the loop at small du.
-  let u = 0;
-
-  function tick(ts) {
-    requestAnimationFrame(tick);
-    for (const p of Object.values(panels)) p?.render();
-    if (!playing) { lastTs = ts; return; }
-    if (!lastTs) { lastTs = ts; return; }
-    const dt = ts - lastTs;
-    lastTs = ts;
-    if (dt <= 0) return;
-    const perFrame = baseMsPerFrame();
-    const T = maxT();
-    u += dt / (perFrame * (T - 1));
-    if (u >= 1) u -= Math.floor(u); // wrap 0..1
-    scrub.value = String(Math.round(u * SCRUB_MAX));
-    applyU(u);
-  }
-  requestAnimationFrame(tick);
-
-  function setPlaying(v) {
-    playing = v;
-    lastTs = 0;
-    playBtn.textContent = playing ? '▮▮' : '▶';
-    playBtn.setAttribute('aria-label', playing ? 'pause' : 'play');
-  }
-  playBtn.addEventListener('click', () => setPlaying(!playing));
-
-  scrub.addEventListener('input', () => {
-    u = parseFloat(scrub.value) / SCRUB_MAX;
-    applyU(u);
-  });
-
-  speedSel.addEventListener('change', () => { lastTs = 0; });
-
-  motionSel.addEventListener('change', () => {
-    applyU(parseFloat(scrub.value) / SCRUB_MAX);
-  });
-
-  function applyColorMode() {
-    const mode = colorSel.value;
-    for (const p of Object.values(panels)) p?.setColorMode(mode);
-  }
-  colorSel.addEventListener('change', applyColorMode);
-  applyColorMode();
-
-  // ---- linked hover -----------------------------------------------------
-  function wireHover(pA, pB) {
-    if (!pA) return;
-    const el = pA.canvasEl;
-    el.addEventListener('mousemove', (ev) => {
-      const id = pA.pickAt(ev.clientX, ev.clientY);
-      pA.setHighlight(id >= 0 ? id : null);
-      if (pB) pB.setHighlight(id >= 0 ? id : null);
-    });
-    el.addEventListener('mouseleave', () => {
-      pA.setHighlight(null);
-      if (pB) pB.setHighlight(null);
-    });
-  }
-  wireHover(panels.a, panels.b);
-  wireHover(panels.b, panels.a);
-
-  // ---- resize + theme ---------------------------------------------------
-  const ro = new ResizeObserver(() => {
-    for (const p of Object.values(panels)) p?.resize();
-  });
-  if (panels.a) ro.observe(panels.a.canvasEl);
-  if (panels.b) ro.observe(panels.b.canvasEl);
-
-  document.addEventListener('themechange', () => {
-    for (const p of Object.values(panels)) p?.applyColorsFromTheme();
-  });
-
-  // Initialise the label + scrub at 0.
-  applyU(0);
-}
-
-main().catch((err) => {
-  console.error(err);
-  renderError(panelElA, STEM_A, 'init failed: ' + err.message);
-  renderError(panelElB, STEM_B, 'init failed: ' + err.message);
-});
+mountPanels({ host, controls, stems });
diff --git a/app/web/static/panel-grid.js b/app/web/static/panel-grid.js
new file mode 100644
index 0000000..22e5124
--- /dev/null
+++ b/app/web/static/panel-grid.js
@@ -0,0 +1,756 @@
+// panel-grid.js — reusable N-panel animated-scatter grid.
+//
+// Single public export: mountPanels({ host, controls, stems }) mounts one
+// three.js panel per stem inside `host`, and wires the shared control strip
+// in `controls` to drive all of them (play/scrub, speed, motion, axes, color,
+// linked hover). Works identically for 1, 2, or N stems.
+
+import * as THREE from 'three';
+
+// ---- viridis (8-stop, RGB lerp) -----------------------------------------
+
+const VIRIDIS_HEX = [
+  '#440154', '#482878', '#3E4989', '#31688E',
+  '#26828E', '#1F9E89', '#6DCD59', '#FDE725',
+];
+
+const VIRIDIS_RGB = VIRIDIS_HEX.map(h => [
+  parseInt(h.slice(1, 3), 16),
+  parseInt(h.slice(3, 5), 16),
+  parseInt(h.slice(5, 7), 16),
+]);
+
+function lerpStops(t) {
+  const n = VIRIDIS_RGB.length;
+  if (t <= 0) return VIRIDIS_RGB[0];
+  if (t >= 1) return VIRIDIS_RGB[n - 1];
+  const x = t * (n - 1);
+  const i = Math.floor(x);
+  const f = x - i;
+  const a = VIRIDIS_RGB[i];
+  const b = VIRIDIS_RGB[i + 1];
+  return [
+    Math.round(a[0] + (b[0] - a[0]) * f),
+    Math.round(a[1] + (b[1] - a[1]) * f),
+    Math.round(a[2] + (b[2] - a[2]) * f),
+  ];
+}
+
+function rgbToHex([r, g, b]) {
+  const h = (v) => v.toString(16).padStart(2, '0');
+  return `#${h(r)}${h(g)}${h(b)}`;
+}
+
+function viridisColor(i, total) {
+  if (total >= 9) return VIRIDIS_HEX[i % VIRIDIS_HEX.length];
+  if (total <= 1) return rgbToHex(lerpStops(0.5));
+  return rgbToHex(lerpStops(i / (total - 1)));
+}
+
+// ---- tiny helpers -------------------------------------------------------
+
+function makeDiskTexture(size = 64) {
+  const c = document.createElement('canvas');
+  c.width = c.height = size;
+  const g = c.getContext('2d');
+  const r = size / 2;
+  const grd = g.createRadialGradient(r, r, 0, r, r, r);
+  grd.addColorStop(0.0, 'rgba(255,255,255,1)');
+  grd.addColorStop(0.55, 'rgba(255,255,255,1)');
+  grd.addColorStop(0.85, 'rgba(255,255,255,0.35)');
+  grd.addColorStop(1.0, 'rgba(255,255,255,0)');
+  g.fillStyle = grd;
+  g.fillRect(0, 0, size, size);
+  const tex = new THREE.CanvasTexture(c);
+  tex.needsUpdate = true;
+  return tex;
+}
+
+function rampContinuous(t, out) {
+  const hue = (1 - t) * 215 + t * 28;
+  const sat = 0.62;
+  const lit = 0.50 + (t - 0.5) * 0.08;
+  return (out || new THREE.Color()).setHSL(hue / 360, sat, lit);
+}
+
+const CATEGORICAL_HEX = [
+  '#1f4e5f', '#c97b3f', '#8b5a9f', '#5a8560',
+  '#c74a5e', '#6b7d8f', '#b89f51', '#4a6fa5',
+];
+const CATEGORICAL = CATEGORICAL_HEX.map(h => new THREE.Color(h));
+
+function buildIdColorsRGB(data) {
+  const n = data.point_ids.length;
+  const rgb = new Float32Array(n * 3);
+  const labels = data.labels || [];
+  const kind = data.label_kind || null;
+  const hasRealLabels = kind && labels.some(v => v != null && v !== '');
+
+  if (hasRealLabels) {
+    const tmp = new THREE.Color();
+    if (kind === 'categorical') {
+      for (let i = 0; i < n; i++) {
+        const v = labels[i];
+        if (v == null) continue;
+        const c = CATEGORICAL[((v | 0) % CATEGORICAL.length + CATEGORICAL.length) % CATEGORICAL.length];
+        rgb[i * 3 + 0] = c.r;
+        rgb[i * 3 + 1] = c.g;
+        rgb[i * 3 + 2] = c.b;
+      }
+    } else {
+      let lo = Infinity, hi = -Infinity;
+      for (const v of labels) { if (v == null) continue; if (v < lo) lo = v; if (v > hi) hi = v; }
+      const range = (hi - lo) || 1;
+      for (let i = 0; i < n; i++) {
+        const v = labels[i];
+        if (v == null) continue;
+        rampContinuous((v - lo) / range, tmp);
+        rgb[i * 3 + 0] = tmp.r;
+        rgb[i * 3 + 1] = tmp.g;
+        rgb[i * 3 + 2] = tmp.b;
+      }
+    }
+    return rgb;
+  }
+
+  const frame0 = data.frames[0];
+  if (!frame0) return rgb;
+  const originalPositions = [];
+  for (let i = 0; i < n; i++) {
+    if (frame0.x[i] != null && frame0.y[i] != null
+        && !Number.isNaN(frame0.x[i]) && !Number.isNaN(frame0.y[i])) {
+      originalPositions.push(i);
+    }
+  }
+  originalPositions.sort((a, b) => data.point_ids[a] - data.point_ids[b]);
+  const nOrig = originalPositions.length;
+  const tmp = new THREE.Color();
+  for (let k = 0; k < nOrig; k++) {
+    const t = nOrig > 1 ? k / (nOrig - 1) : 0.5;
+    rampContinuous(t, tmp);
+    const idx = originalPositions[k];
+    rgb[idx * 3 + 0] = tmp.r;
+    rgb[idx * 3 + 1] = tmp.g;
+    rgb[idx * 3 + 2] = tmp.b;
+  }
+  return rgb;
+}
+
+function readVar(name, fallback) {
+  const v = getComputedStyle(document.documentElement).getPropertyValue(name).trim();
+  return v || fallback;
+}
+
+function readPanelBg(el) {
+  const v = getComputedStyle(el).getPropertyValue('--picker-panel').trim();
+  return v || readVar('--panel', '#ffffff');
+}
+
+function readPanelColor(el, fallback) {
+  const v = getComputedStyle(el).getPropertyValue('--panel-color').trim();
+  return v || fallback;
+}
+
+function highlightColor() {
+  return readVar('--alarm', '#8a3a2a');
+}
+
+const PARAM_FIELDS = [
+  { key: 'num_points',    prefix: 'N' },
+  { key: 'num_timesteps', prefix: 'T' },
+  { key: 'jitter_scale',  prefix: 'J' },
+  { key: 'seed',          prefix: 's' },
+];
+
+function renderHeader(panelEl, data) {
+  const m = data.meta || {};
+  panelEl.querySelector('[data-role="embedder"]').textContent = m.embedder || '—';
+  panelEl.querySelector('[data-role="generator"]').textContent = m.generator || '—';
+  const host = panelEl.querySelector('[data-role="params"]');
+  host.textContent = '';
+  PARAM_FIELDS.forEach(({ key, prefix }, i) => {
+    if (i > 0) host.appendChild(document.createTextNode(' / '));
+    const span = document.createElement('span');
+    span.className = 'param';
+    span.dataset.key = key;
+    span.textContent = `${prefix}${m[key] ?? '?'}`;
+    host.appendChild(span);
+  });
+  const stemLink = panelEl.querySelector('[data-role="stem-link"]');
+  if (stemLink && panelEl.dataset.stem) {
+    stemLink.href = `/api/runs/${encodeURIComponent(panelEl.dataset.stem)}/frames.json`;
+  }
+}
+
+function renderError(panelEl, stem, msg) {
+  const statusEl = panelEl.querySelector('[data-role="status"]');
+  statusEl.style.display = '';
+  statusEl.classList.add('is-error');
+  statusEl.textContent = `could not load ${stem}: ${msg}`;
+  panelEl.querySelector('[data-role="embedder"]').textContent = '—';
+  panelEl.querySelector('[data-role="generator"]').textContent = '—';
+  panelEl.querySelector('[data-role="params"]').textContent = '(error)';
+}
+
+function markParamDiffs(panels) {
+  if (panels.length < 2) return;
+  const metas = panels.map(p => p.data.meta || {});
+  for (const { key } of PARAM_FIELDS) {
+    const vals = metas.map(m => m[key]);
+    const differs = vals.some(v => v !== vals[0]);
+    for (const p of panels) {
+      const span = p.panelEl.querySelector(`[data-role="params"] .param[data-key="${key}"]`);
+      if (span) span.classList.toggle('diff', differs);
+    }
+  }
+  for (const role of ['embedder', 'generator']) {
+    const vals = metas.map(m => m[role]);
+    const differs = vals.some(v => v !== vals[0]);
+    for (const p of panels) {
+      const span = p.panelEl.querySelector(`[data-role="${role}"]`);
+      if (span) span.classList.toggle('diff', differs);
+    }
+  }
+}
+
+// ---- Panel factory ------------------------------------------------------
+
+const DISK_TEX = makeDiskTexture();
+
+function createPanel({ panelEl, data }) {
+  const canvasEl = panelEl.querySelector('[data-role="canvas"]');
+  const statusEl = panelEl.querySelector('[data-role="status"]');
+
+  const scene = new THREE.Scene();
+  scene.background = new THREE.Color(readPanelBg(panelEl));
+
+  const camera = new THREE.OrthographicCamera(-1, 1, 1, -1, -10, 10);
+  const renderer = new THREE.WebGLRenderer({ antialias: true, alpha: false });
+  renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2));
+  canvasEl.appendChild(renderer.domElement);
+
+  const maxN = data.point_ids.length;
+  const positions = new Float32Array(maxN * 3);
+  const colors = new Float32Array(maxN * 3);
+  const idColorRGB = buildIdColorsRGB(data);
+
+  const geo = new THREE.BufferGeometry();
+  geo.setAttribute('position', new THREE.BufferAttribute(positions, 3));
+  geo.setAttribute('color', new THREE.BufferAttribute(colors, 3));
+  geo.setDrawRange(0, 0);
+
+  const matMono = new THREE.PointsMaterial({
+    size: 6.0,
+    sizeAttenuation: false,
+    map: DISK_TEX,
+    transparent: true,
+    alphaTest: 0.2,
+    depthWrite: false,
+    color: new THREE.Color(readPanelColor(panelEl, '#26828E')),
+  });
+  const matRainbow = new THREE.PointsMaterial({
+    size: 6.0,
+    sizeAttenuation: false,
+    map: DISK_TEX,
+    transparent: false,
+    alphaTest: 0.5,
+    vertexColors: true,
+  });
+  let mat = matMono;
+  const points = new THREE.Points(geo, mat);
+  scene.add(points);
+
+  const hiPos = new Float32Array(3);
+  const hiGeo = new THREE.BufferGeometry();
+  hiGeo.setAttribute('position', new THREE.BufferAttribute(hiPos, 3));
+  hiGeo.setDrawRange(0, 0);
+  const hiMat = new THREE.PointsMaterial({
+    size: 14.0,
+    sizeAttenuation: false,
+    map: DISK_TEX,
+    transparent: true,
+    alphaTest: 0.05,
+    depthWrite: false,
+    color: new THREE.Color(highlightColor()),
+    opacity: 0.9,
+  });
+  const hiPoints = new THREE.Points(hiGeo, hiMat);
+  hiPoints.renderOrder = 1;
+  scene.add(hiPoints);
+
+  let packedN = 0;
+  const packedX = new Float32Array(maxN);
+  const packedY = new Float32Array(maxN);
+  const packedId = new Int32Array(maxN);
+
+  const camRect = { xmin: -1, xmax: 1, ymin: -1, ymax: 1 };
+
+  function applyCamRect(rect) {
+    const pad = 0.05;
+    const dx = rect.xmax - rect.xmin || 1;
+    const dy = rect.ymax - rect.ymin || 1;
+    const cx = (rect.xmin + rect.xmax) / 2;
+    const cy = (rect.ymin + rect.ymax) / 2;
+    const rx = dx * (0.5 + pad);
+    const ry = dy * (0.5 + pad);
+    const rect2 = canvasEl.getBoundingClientRect();
+    const vw = Math.max(1, rect2.width);
+    const vh = Math.max(1, rect2.height);
+    const aspect = vw / vh;
+    const dataAspect = (rx * 2) / (ry * 2);
+    let halfW, halfH;
+    if (aspect > dataAspect) {
+      halfH = ry;
+      halfW = ry * aspect;
+    } else {
+      halfW = rx;
+      halfH = rx / aspect;
+    }
+    camera.left = cx - halfW;
+    camera.right = cx + halfW;
+    camera.top = cy + halfH;
+    camera.bottom = cy - halfH;
+    camera.updateProjectionMatrix();
+    camRect.xmin = rect.xmin;
+    camRect.xmax = rect.xmax;
+    camRect.ymin = rect.ymin;
+    camRect.ymax = rect.ymax;
+  }
+
+  function resize() {
+    const rect = canvasEl.getBoundingClientRect();
+    const w = Math.max(1, Math.floor(rect.width));
+    const h = Math.max(1, Math.floor(rect.height));
+    renderer.setSize(w, h, false);
+    applyCamRect(camRect);
+  }
+
+  function setBounds(b) {
+    applyCamRect({ xmin: b.x[0], xmax: b.x[1], ymin: b.y[0], ymax: b.y[1] });
+  }
+
+  function applyColorsFromTheme() {
+    matMono.color.set(readPanelColor(panelEl, '#26828E'));
+    hiMat.color.set(highlightColor());
+    scene.background = new THREE.Color(readPanelBg(panelEl));
+  }
+
+  function setColorMode(mode) {
+    const next = mode === 'mono' ? matMono : matRainbow;
+    if (points.material !== next) {
+      points.material = next;
+      mat = next;
+    }
+  }
+
+  function writePackedColor(j, i) {
+    colors[j * 3 + 0] = idColorRGB[i * 3 + 0];
+    colors[j * 3 + 1] = idColorRGB[i * 3 + 1];
+    colors[j * 3 + 2] = idColorRGB[i * 3 + 2];
+  }
+
+  function setFrame(f) {
+    const frame = data.frames[f];
+    if (!frame) return;
+    const xs = frame.x, ys = frame.y;
+    const ptIds = data.point_ids;
+    let j = 0;
+    for (let i = 0; i < xs.length; i++) {
+      const x = xs[i], y = ys[i];
+      if (x === null || y === null || x === undefined || y === undefined
+          || Number.isNaN(x) || Number.isNaN(y)) continue;
+      positions[j * 3 + 0] = x;
+      positions[j * 3 + 1] = y;
+      positions[j * 3 + 2] = 0;
+      writePackedColor(j, i);
+      packedX[j] = x;
+      packedY[j] = y;
+      packedId[j] = ptIds[i];
+      j++;
+    }
+    packedN = j;
+    geo.attributes.position.needsUpdate = true;
+    geo.attributes.color.needsUpdate = true;
+    geo.setDrawRange(0, packedN);
+    applyHighlightForCurrentFrame();
+  }
+
+  function setFrameInterpolated(uLocal) {
+    const T = data.frames.length;
+    if (T === 0) return;
+    if (uLocal <= 0)        return setFrame(0);
+    if (uLocal >= T - 1)    return setFrame(T - 1);
+    const f0 = Math.floor(uLocal);
+    const f1 = f0 + 1;
+    const t  = uLocal - f0;
+    const fr0 = data.frames[f0], fr1 = data.frames[f1];
+    const x0 = fr0.x, y0 = fr0.y, x1 = fr1.x, y1 = fr1.y;
+    const ptIds = data.point_ids;
+    let j = 0;
+    for (let i = 0; i < x0.length; i++) {
+      const a = x0[i], b = x1[i], c = y0[i], d = y1[i];
+      if (a === null || a === undefined || Number.isNaN(a)
+          || b === null || b === undefined || Number.isNaN(b)
+          || c === null || c === undefined || Number.isNaN(c)
+          || d === null || d === undefined || Number.isNaN(d)) continue;
+      const xi = a + (b - a) * t;
+      const yi = c + (d - c) * t;
+      positions[j * 3 + 0] = xi;
+      positions[j * 3 + 1] = yi;
+      positions[j * 3 + 2] = 0;
+      writePackedColor(j, i);
+      packedX[j] = xi;
+      packedY[j] = yi;
+      packedId[j] = ptIds[i];
+      j++;
+    }
+    packedN = j;
+    geo.attributes.position.needsUpdate = true;
+    geo.attributes.color.needsUpdate = true;
+    geo.setDrawRange(0, packedN);
+    applyHighlightForCurrentFrame();
+  }
+
+  let currentHighlightId = -1;
+
+  function applyHighlightForCurrentFrame() {
+    if (currentHighlightId < 0) {
+      hiGeo.setDrawRange(0, 0);
+      return;
+    }
+    for (let i = 0; i < packedN; i++) {
+      if (packedId[i] === currentHighlightId) {
+        hiPos[0] = packedX[i];
+        hiPos[1] = packedY[i];
+        hiPos[2] = 0.01;
+        hiGeo.attributes.position.needsUpdate = true;
+        hiGeo.setDrawRange(0, 1);
+        return;
+      }
+    }
+    hiGeo.setDrawRange(0, 0);
+  }
+
+  function setHighlight(pointId) {
+    currentHighlightId = (pointId === null || pointId === undefined) ? -1 : pointId;
+    applyHighlightForCurrentFrame();
+  }
+
+  function clientToWorld(clientX, clientY) {
+    const rect = canvasEl.getBoundingClientRect();
+    const u = (clientX - rect.left) / Math.max(1, rect.width);
+    const v = (clientY - rect.top) / Math.max(1, rect.height);
+    const wx = camera.left + u * (camera.right - camera.left);
+    const wy = camera.top - v * (camera.top - camera.bottom);
+    return { wx, wy };
+  }
+
+  function pickAt(clientX, clientY) {
+    if (packedN === 0) return -1;
+    const { wx, wy } = clientToWorld(clientX, clientY);
+    const rect = canvasEl.getBoundingClientRect();
+    const worldPerPx = (camera.right - camera.left) / Math.max(1, rect.width);
+    const pickPx = 14;
+    const maxR = pickPx * worldPerPx;
+    const maxR2 = maxR * maxR;
+    let bestI = -1;
+    let bestD2 = Infinity;
+    for (let i = 0; i < packedN; i++) {
+      const dx = packedX[i] - wx;
+      const dy = packedY[i] - wy;
+      const d2 = dx * dx + dy * dy;
+      if (d2 < bestD2 && d2 < maxR2) {
+        bestD2 = d2;
+        bestI = i;
+      }
+    }
+    return bestI < 0 ? -1 : packedId[bestI];
+  }
+
+  function render() {
+    renderer.render(scene, camera);
+  }
+
+  function dispose() {
+    geo.dispose();
+    hiGeo.dispose();
+    matMono.dispose();
+    matRainbow.dispose();
+    hiMat.dispose();
+    renderer.dispose();
+    if (renderer.domElement.parentNode) {
+      renderer.domElement.parentNode.removeChild(renderer.domElement);
+    }
+  }
+
+  statusEl.style.display = 'none';
+
+  return {
+    canvasEl,
+    panelEl,
+    data,
+    setFrame,
+    setFrameInterpolated,
+    setColorMode,
+    setBounds,
+    setHighlight,
+    resize,
+    render,
+    pickAt,
+    applyColorsFromTheme,
+    dispose,
+    applyCamRect,
+    get packedN() { return packedN; },
+    get camRect() { return camRect; },
+  };
+}
+
+// ---- frames.json fetch --------------------------------------------------
+
+async function fetchFrames(stem) {
+  const res = await fetch(`/api/runs/${encodeURIComponent(stem)}/frames.json`, { cache: 'no-store' });
+  if (!res.ok) throw new Error(`${res.status} ${res.statusText}`);
+  return res.json();
+}
+
+// ---- public API ---------------------------------------------------------
+
+/**
+ * Mount one three.js panel per stem into `host`, driven by the control strip
+ * at `controls`. Returns `{ destroy }` for teardown (disposes every WebGL
+ * context and removes the panel DOM nodes).
+ */
+export function mountPanels({ host, controls, stems }) {
+  const tpl = document.getElementById('compare-panel-tpl');
+  if (!tpl) throw new Error('panel-grid: #compare-panel-tpl not found');
+
+  host.innerHTML = '';
+  const total = stems.length;
+
+  const slots = stems.map((stem, i) => {
+    const frag = tpl.content.cloneNode(true);
+    const panelEl = frag.querySelector('.compare-panel');
+    const color = viridisColor(i, total);
+    panelEl.style.setProperty('--panel-color', color);
+    panelEl.dataset.stem = stem;
+    host.appendChild(panelEl);
+    return { stem, panelEl, color, panel: null };
+  });
+
+  // Build the per-panel time segments inside #cc-times.
+  const timesHost = controls.querySelector('#cc-times');
+  if (timesHost) {
+    timesHost.innerHTML = '';
+    slots.forEach((s, i) => {
+      if (i > 0) {
+        const sep = document.createElement('span');
+        sep.className = 'cc-time-sep';
+        sep.textContent = '/';
+        timesHost.appendChild(sep);
+      }
+      const seg = document.createElement('span');
+      seg.className = 'cc-time-seg';
+      seg.style.setProperty('--panel-color', s.color);
+      seg.textContent = '—';
+      timesHost.appendChild(seg);
+      s.timeEl = seg;
+    });
+  }
+
+  const playBtn  = controls.querySelector('#cc-play');
+  const scrub    = controls.querySelector('#cc-scrub');
+  const speedSel = controls.querySelector('#cc-speed');
+  const syncSel  = controls.querySelector('#cc-sync');
+  const motionSel= controls.querySelector('#cc-motion');
+  const colorSel = controls.querySelector('#cc-color');
+
+  // Reset controls to a clean state (they may be reused across opens).
+  if (scrub)   scrub.value = '0';
+  if (playBtn) { playBtn.textContent = '▶'; playBtn.setAttribute('aria-label', 'play'); }
+
+  // Parallel fetch; each panel's error is independent.
+  const ready = Promise.allSettled(stems.map(fetchFrames)).then((results) => {
+    results.forEach((res, i) => {
+      const slot = slots[i];
+      if (res.status === 'fulfilled') {
+        renderHeader(slot.panelEl, res.value);
+        slot.panel = createPanel({ panelEl: slot.panelEl, data: res.value });
+      } else {
+        renderError(slot.panelEl, slot.stem, res.reason?.message || String(res.reason));
+      }
+    });
+
+    const live = slots.filter(s => s.panel);
+    markParamDiffs(live.map(s => s.panel));
+    if (!live.length) return;
+
+    for (const s of live) {
+      s.panel.setBounds(s.panel.data.bounds);
+      s.panel.resize();
+      s.panel.setFrame(0);
+    }
+
+    wireDrivers(live);
+  });
+
+  function wireDrivers(live) {
+    const SCRUB_MAX = 1000;
+
+    function framesOf(p) { return p ? p.data.frames.length : 0; }
+    function maxT() {
+      let m = 2;
+      for (const s of live) m = Math.max(m, framesOf(s.panel));
+      return m;
+    }
+    function timeLabelFor(p, uLocal) {
+      const T = framesOf(p);
+      if (T <= 0) return '—';
+      const idx = Math.max(0, Math.min(T - 1, Math.round(uLocal)));
+      return p.data.times?.[idx] ?? String(idx);
+    }
+
+    function applyU(u) {
+      u = Math.max(0, Math.min(1, u));
+      const smooth = motionSel.value === 'smooth';
+      const tMax = maxT();
+      const uGlobal = u * (tMax - 1);
+      for (const s of live) {
+        const p = s.panel;
+        const T = framesOf(p);
+        if (T <= 0) continue;
+        const uLocal = Math.min(uGlobal, T - 1);
+        if (smooth) p.setFrameInterpolated(uLocal);
+        else {
+          const idx = Math.max(0, Math.min(T - 1, Math.round(uLocal)));
+          p.setFrame(idx);
+        }
+        if (s.timeEl) s.timeEl.textContent = timeLabelFor(p, uLocal);
+      }
+    }
+
+    function applySync() {
+      const mode = syncSel ? syncSel.value : 'independent';
+      if (mode === 'locked' && live.length > 1) {
+        let xmin = +Infinity, xmax = -Infinity, ymin = +Infinity, ymax = -Infinity;
+        for (const s of live) {
+          const b = s.panel.data.bounds;
+          if (b.x[0] < xmin) xmin = b.x[0];
+          if (b.x[1] > xmax) xmax = b.x[1];
+          if (b.y[0] < ymin) ymin = b.y[0];
+          if (b.y[1] > ymax) ymax = b.y[1];
+        }
+        const union = { x: [xmin, xmax], y: [ymin, ymax] };
+        for (const s of live) s.panel.setBounds(union);
+      } else {
+        for (const s of live) s.panel.setBounds(s.panel.data.bounds);
+      }
+    }
+    if (syncSel) onCtl(syncSel, 'change', applySync);
+    applySync();
+
+    let playing = false;
+    let lastTs = 0;
+    let u = 0;
+    function baseMsPerFrame() { return 1600 / parseFloat(speedSel?.value || '1'); }
+
+    function tick(ts) {
+      if (stopped) return;
+      rafId = requestAnimationFrame(tick);
+      for (const s of live) s.panel.render();
+      if (!playing) { lastTs = ts; return; }
+      if (!lastTs) { lastTs = ts; return; }
+      const dt = ts - lastTs;
+      lastTs = ts;
+      if (dt <= 0) return;
+      const perFrame = baseMsPerFrame();
+      const T = maxT();
+      u += dt / (perFrame * (T - 1));
+      if (u >= 1) u -= Math.floor(u);
+      if (scrub) scrub.value = String(Math.round(u * SCRUB_MAX));
+      applyU(u);
+    }
+    rafId = requestAnimationFrame(tick);
+
+    function setPlaying(v) {
+      playing = v;
+      lastTs = 0;
+      if (playBtn) {
+        playBtn.textContent = playing ? '▮▮' : '▶';
+        playBtn.setAttribute('aria-label', playing ? 'pause' : 'play');
+      }
+    }
+    if (playBtn) onCtl(playBtn, 'click', () => setPlaying(!playing));
+
+    if (scrub) onCtl(scrub, 'input', () => {
+      u = parseFloat(scrub.value) / SCRUB_MAX;
+      applyU(u);
+    });
+
+    if (speedSel) onCtl(speedSel, 'change', () => { lastTs = 0; });
+
+    if (motionSel) onCtl(motionSel, 'change', () => {
+      applyU(parseFloat(scrub?.value || '0') / SCRUB_MAX);
+    });
+
+    function applyColorMode() {
+      const mode = colorSel ? colorSel.value : 'original';
+      for (const s of live) s.panel.setColorMode(mode);
+    }
+    if (colorSel) onCtl(colorSel, 'change', applyColorMode);
+    applyColorMode();
+
+    // Linked hover across every panel.
+    for (const s of live) {
+      const mm = (ev) => {
+        const id = s.panel.pickAt(ev.clientX, ev.clientY);
+        const hid = id >= 0 ? id : null;
+        for (const t of live) t.panel.setHighlight(hid);
+      };
+      const ml = () => { for (const t of live) t.panel.setHighlight(null); };
+      s.panel.canvasEl.addEventListener('mousemove', mm);
+      s.panel.canvasEl.addEventListener('mouseleave', ml);
+      listeners.push({ el: s.panel.canvasEl, ev: 'mousemove', fn: mm });
+      listeners.push({ el: s.panel.canvasEl, ev: 'mouseleave', fn: ml });
+    }
+
+    // Resize + theme observers.
+    ro = new ResizeObserver(() => { for (const s of live) s.panel.resize(); });
+    for (const s of live) ro.observe(s.panel.canvasEl);
+
+    themeFn = () => { for (const s of live) s.panel.applyColorsFromTheme(); };
+    document.addEventListener('themechange', themeFn);
+
+    applyU(0);
+  }
+
+  // ---- teardown bookkeeping ---------------------------------------------
+  const listeners = [];
+  const ctlListeners = [];
+  let rafId = 0;
+  let stopped = false;
+  let ro = null;
+  let themeFn = null;
+
+  function onCtl(el, ev, fn) {
+    el.addEventListener(ev, fn);
+    ctlListeners.push({ el, ev, fn });
+  }
+
+  function destroy() {
+    stopped = true;
+    if (rafId) cancelAnimationFrame(rafId);
+    if (ro) ro.disconnect();
+    if (themeFn) document.removeEventListener('themechange', themeFn);
+    for (const { el, ev, fn } of listeners) el.removeEventListener(ev, fn);
+    for (const { el, ev, fn } of ctlListeners) el.removeEventListener(ev, fn);
+    for (const s of slots) {
+      if (s.panel) s.panel.dispose();
+      if (s.panelEl.parentNode) s.panelEl.parentNode.removeChild(s.panelEl);
+    }
+    host.innerHTML = '';
+    const timesHost2 = controls.querySelector('#cc-times');
+    if (timesHost2) timesHost2.innerHTML = '';
+  }
+
+  return { destroy, ready };
+}
diff --git a/app/web/static/run-modal.js b/app/web/static/run-modal.js
new file mode 100644
index 0000000..4764c88
--- /dev/null
+++ b/app/web/static/run-modal.js
@@ -0,0 +1,69 @@
+// run-modal.js — homepage click-hijack for embedding links. Opens a
+// <dialog id="run-modal"> that renders the run's embedding via panel-grid.js.
+
+import { mountPanels } from './panel-grid.js?v=1';
+
+const dialog = document.getElementById('run-modal');
+const host = document.getElementById('modal-panel-host');
+const controls = document.getElementById('modal-compare-controls');
+const closeBtn = document.getElementById('run-modal-close');
+const runsSlot = document.getElementById('runs-slot');
+
+let active = null; // { destroy } returned by mountPanels
+
+function openFor(stem) {
+  if (!dialog || !host || !controls) return;
+  if (active) { try { active.destroy(); } catch (_) {} active = null; }
+  active = mountPanels({ host, controls, stems: [stem] });
+  if (typeof dialog.showModal === 'function') dialog.showModal();
+  else dialog.setAttribute('open', '');
+}
+
+function closeModal() {
+  if (!dialog) return;
+  if (dialog.open) dialog.close();
+  if (active) { try { active.destroy(); } catch (_) {} active = null; }
+}
+
+function onRunsClick(ev) {
+  if (ev.defaultPrevented) return;
+  if (ev.button !== undefined && ev.button !== 0) return;
+  if (ev.metaKey || ev.ctrlKey || ev.shiftKey || ev.altKey) return;
+  const a = ev.target.closest('a[data-role="embedding-link"]');
+  if (!a) return;
+  if (!runsSlot || !runsSlot.contains(a)) return;
+  const stem = a.dataset.stem;
+  if (!stem) return;
+  ev.preventDefault();
+  openFor(stem);
+}
+
+function wire() {
+  if (!dialog) return;
+  if (runsSlot) runsSlot.addEventListener('click', onRunsClick);
+  if (closeBtn) closeBtn.addEventListener('click', closeModal);
+  dialog.addEventListener('close', () => {
+    if (active) { try { active.destroy(); } catch (_) {} active = null; }
+  });
+  // Clicking the backdrop (native behavior fires a click on the dialog
+  // itself, with target === dialog) closes the modal.
+  dialog.addEventListener('click', (ev) => {
+    if (ev.target === dialog) closeModal();
+  });
+}
+
+if (document.readyState === 'loading') {
+  document.addEventListener('DOMContentLoaded', wire);
+} else {
+  wire();
+}
+
+// htmx re-renders #runs-slot every 3s. Delegation on #runs-slot survives the
+// swap (the slot element itself is stable), so we don't need to re-bind —
+// but we keep the hook in case a consumer ever replaces the slot wholesale.
+document.body.addEventListener('htmx:afterSwap', (ev) => {
+  if (ev.detail?.target?.id === 'runs-slot' && runsSlot && !runsSlot._runModalWired) {
+    runsSlot.addEventListener('click', onRunsClick);
+    runsSlot._runModalWired = true;
+  }
+});
diff --git a/app/web/static/style.css b/app/web/static/style.css
index f6072ef..62dca48 100644
--- a/app/web/static/style.css
+++ b/app/web/static/style.css
@@ -1473,11 +1473,12 @@ button.submit:disabled { background: var(--faint); border-color: var(--faint); c
 
 .compare-grid {
   display: grid;
-  grid-template-columns: 1fr 1fr;
+  grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
   gap: 1rem;
 }
 
 .compare-panel {
+  --panel-color: var(--accent);
   display: flex;
   flex-direction: column;
   border: 1px solid var(--rule);
@@ -1505,19 +1506,14 @@ button.submit:disabled { background: var(--faint); border-color: var(--faint); c
   min-width: 1.2em;
   padding: 0 0.35rem;
   border-radius: 2px;
-  background: var(--accent-tint);
-  color: var(--accent);
+  background: color-mix(in srgb, var(--panel-color) 14%, transparent);
+  color: var(--panel-color);
   font-weight: 600;
   text-align: center;
   font-size: 0.72rem;
   letter-spacing: 0.04em;
 }
 
-.compare-panel[data-slot="b"] .compare-panel-head .panel-tag {
-  color: var(--warm);
-  background: color-mix(in srgb, var(--warm) 14%, transparent);
-}
-
 .compare-panel-head .panel-embedder {
   color: var(--ink);
   font-weight: 600;
@@ -1639,8 +1635,7 @@ button.submit:disabled { background: var(--faint); border-color: var(--faint); c
   font-variant-numeric: tabular-nums;
 }
 .compare-controls .cc-time-sep { color: var(--faint); }
-.compare-controls .cc-time-a { color: var(--accent); }
-.compare-controls .cc-time-b { color: var(--warm); }
+.compare-controls .cc-time-seg { color: var(--panel-color, var(--ink)); }
 
 .compare-controls .cc-speed-wrap,
 .compare-controls .cc-sync-wrap,
@@ -1679,5 +1674,60 @@ button.submit:disabled { background: var(--faint); border-color: var(--faint); c
 
 @media (max-width: 900px) {
   .compare-layout { --panel-h: 45vh; padding: 1rem 0.9rem 1.2rem; }
-  .compare-grid { grid-template-columns: 1fr; }
+}
+
+/* ---------- run modal --------------------------------------------------- */
+
+#run-modal {
+  width: min(1200px, 94vw);
+  max-width: 94vw;
+  height: min(820px, 88vh);
+  max-height: 88vh;
+  padding: 0;
+  border: 1px solid var(--rule);
+  border-radius: 4px;
+  background: var(--panel);
+  color: var(--ink);
+}
+#run-modal::backdrop {
+  background: color-mix(in srgb, #000 48%, transparent);
+}
+.run-modal-body {
+  display: flex;
+  flex-direction: column;
+  gap: 0.8rem;
+  height: 100%;
+  padding: 0.8rem 1rem 1rem;
+  box-sizing: border-box;
+  --panel-h: 62vh;
+}
+.run-modal-head {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 0.5rem;
+  font-family: var(--mono);
+  font-size: 0.82rem;
+  color: var(--mute);
+}
+.run-modal-close {
+  appearance: none;
+  border: 1px solid var(--rule-2);
+  background: var(--panel);
+  color: var(--ink);
+  width: 1.9rem;
+  height: 1.9rem;
+  border-radius: 2px;
+  cursor: pointer;
+  font-size: 1rem;
+  line-height: 1;
+}
+.run-modal-close:hover {
+  background: var(--accent-tint);
+  border-color: var(--accent);
+  color: var(--accent);
+}
+#run-modal .compare-grid {
+  flex: 1 1 auto;
+  min-height: 0;
 }
diff --git a/app/web/templates/_runs.html b/app/web/templates/_runs.html
index 2254f6e..91712c4 100644
--- a/app/web/templates/_runs.html
+++ b/app/web/templates/_runs.html
@@ -60,7 +60,8 @@
 
             {% if r.emb_file %}
               {% if r.emb_exists %}
-                <a href="/figs/{{ r.emb_file }}" target="_blank" rel="noopener">embedding</a>
+                <a href="/figs/{{ r.emb_file }}" data-role="embedding-link"
+                   data-stem="{{ r.emb_file[:-5] }}" target="_blank" rel="noopener">embedding</a>
               {% else %}
                 <a aria-disabled="true">embedding</a>
               {% endif %}
diff --git a/app/web/templates/compare.html b/app/web/templates/compare.html
index 2df62da..6414340 100644
--- a/app/web/templates/compare.html
+++ b/app/web/templates/compare.html
@@ -4,7 +4,7 @@
   <meta charset="utf-8" />
   <meta name="viewport" content="width=device-width,initial-scale=1" />
   <title>embedding notebook &middot; compare</title>
-  <link rel="stylesheet" href="/static/style.css?v=27" />
+  <link rel="stylesheet" href="/static/style.css?v=28" />
   <script type="importmap">
   {
     "imports": {
@@ -43,11 +43,7 @@
     <input class="cc-scrub" id="cc-scrub" type="range"
            min="0" max="1000" step="1" value="0" aria-label="time scrubber" />
 
-    <div class="cc-time" id="cc-time">
-      <span class="cc-time-a" data-role="time-a">&mdash;</span>
-      <span class="cc-time-sep">/</span>
-      <span class="cc-time-b" data-role="time-b">&mdash;</span>
-    </div>
+    <div class="cc-time" id="cc-times"></div>
 
     <label class="cc-speed-wrap">
       <span class="cc-lbl">speed</span>
@@ -84,40 +80,26 @@
     </label>
   </div>
 
-  <div class="compare-grid">
-    <article class="compare-panel" data-slot="a">
-      <header class="compare-panel-head">
-        <span class="panel-tag" data-role="label">A</span>
-        <span class="panel-embedder" data-role="embedder">&hellip;</span>
-        <span class="panel-sep">&middot;</span>
-        <span class="panel-generator" data-role="generator">&hellip;</span>
-        <a class="panel-stem" data-role="stem-link"
-           href="/api/runs/{{ stem_a }}/frames.json" target="_blank">&#x2197;</a>
-        <span class="panel-params" data-role="params">loading&hellip;</span>
-      </header>
-      <div class="compare-canvas" data-role="canvas">
-        <div class="compare-status" data-role="status">loading&hellip;</div>
-      </div>
-    </article>
-
-    <article class="compare-panel" data-slot="b">
-      <header class="compare-panel-head">
-        <span class="panel-tag" data-role="label">B</span>
-        <span class="panel-embedder" data-role="embedder">&hellip;</span>
-        <span class="panel-sep">&middot;</span>
-        <span class="panel-generator" data-role="generator">&hellip;</span>
-        <a class="panel-stem" data-role="stem-link"
-           href="/api/runs/{{ stem_b }}/frames.json" target="_blank">&#x2197;</a>
-        <span class="panel-params" data-role="params">loading&hellip;</span>
-      </header>
-      <div class="compare-canvas" data-role="canvas">
-        <div class="compare-status" data-role="status">loading&hellip;</div>
-      </div>
-    </article>
-  </div>
+  <div class="compare-grid" id="panel-host"></div>
 
 </section>
 
+<template id="compare-panel-tpl">
+  <article class="compare-panel">
+    <header class="compare-panel-head">
+      <span class="panel-tag" data-role="label">&#9679;</span>
+      <span class="panel-embedder" data-role="embedder">&hellip;</span>
+      <span class="panel-sep">&middot;</span>
+      <span class="panel-generator" data-role="generator">&hellip;</span>
+      <a class="panel-stem" data-role="stem-link" href="#" target="_blank">&#x2197;</a>
+      <span class="panel-params" data-role="params">loading&hellip;</span>
+    </header>
+    <div class="compare-canvas" data-role="canvas">
+      <div class="compare-status" data-role="status">loading&hellip;</div>
+    </div>
+  </article>
+</template>
+
 <script src="/static/theme.js?v=11"></script>
 <script type="module" src="/static/compare.js?v=11"></script>
 </body>
diff --git a/app/web/templates/index.html b/app/web/templates/index.html
index a04e1db..0de1435 100644
--- a/app/web/templates/index.html
+++ b/app/web/templates/index.html
@@ -4,7 +4,7 @@
   <meta charset="utf-8" />
   <meta name="viewport" content="width=device-width,initial-scale=1" />
   <title>embedding notebook</title>
-  <link rel="stylesheet" href="/static/style.css?v=27" />
+  <link rel="stylesheet" href="/static/style.css?v=28" />
   <script src="https://unpkg.com/htmx.org@2.0.4"></script>
   <script type="importmap">
   {
@@ -396,6 +396,70 @@
   </div>
 </details>
 
+<dialog id="run-modal" aria-label="run embedding">
+  <div class="run-modal-body">
+    <div class="run-modal-head">
+      <span>embedding</span>
+      <button type="button" class="run-modal-close" id="run-modal-close" aria-label="close">&times;</button>
+    </div>
+
+    <div class="compare-controls" id="modal-compare-controls">
+      <button type="button" class="cc-play" id="cc-play" aria-label="play / pause">&#9654;</button>
+      <input class="cc-scrub" id="cc-scrub" type="range"
+             min="0" max="1000" step="1" value="0" aria-label="time scrubber" />
+      <div class="cc-time" id="cc-times"></div>
+      <label class="cc-speed-wrap">
+        <span class="cc-lbl">speed</span>
+        <select class="cc-speed" id="cc-speed">
+          <option value="0.5">0.5&times;</option>
+          <option value="1" selected>1&times;</option>
+          <option value="2">2&times;</option>
+          <option value="4">4&times;</option>
+        </select>
+      </label>
+      <label class="cc-motion-wrap">
+        <span class="cc-lbl">motion</span>
+        <select class="cc-motion" id="cc-motion">
+          <option value="smooth" selected>smooth</option>
+          <option value="step">step</option>
+        </select>
+      </label>
+      <label class="cc-color-wrap">
+        <span class="cc-lbl">color</span>
+        <select class="cc-color" id="cc-color">
+          <option value="mono">mono</option>
+          <option value="original" selected>original</option>
+        </select>
+      </label>
+      <label class="cc-sync-wrap">
+        <span class="cc-lbl">axes</span>
+        <select class="cc-sync" id="cc-sync">
+          <option value="independent" selected>independent</option>
+          <option value="locked">locked</option>
+        </select>
+      </label>
+    </div>
+
+    <div class="compare-grid" id="modal-panel-host"></div>
+  </div>
+</dialog>
+
+<template id="compare-panel-tpl">
+  <article class="compare-panel">
+    <header class="compare-panel-head">
+      <span class="panel-tag" data-role="label">&#9679;</span>
+      <span class="panel-embedder" data-role="embedder">&hellip;</span>
+      <span class="panel-sep">&middot;</span>
+      <span class="panel-generator" data-role="generator">&hellip;</span>
+      <a class="panel-stem" data-role="stem-link" href="#" target="_blank">&#x2197;</a>
+      <span class="panel-params" data-role="params">loading&hellip;</span>
+    </header>
+    <div class="compare-canvas" data-role="canvas">
+      <div class="compare-status" data-role="status">loading&hellip;</div>
+    </div>
+  </article>
+</template>
+
 <footer class="colophon">
   <span>&copy; 2026 Mind the Math LLC</span>
   <span class="prefect-badge">
@@ -408,6 +472,7 @@
 <script type="module" src="/static/dataset-picker.js?v=11"></script>
 <script type="module" src="/static/metrics.js?v=11"></script>
 <script src="/static/compare-select.js?v=1"></script>
+<script type="module" src="/static/run-modal.js?v=1"></script>
 <script>
   // Anchor-links alone don't expand <details>; force it.
   document.querySelector('a[href="#metrics"]')?.addEventListener('click', () => {