diff --git a/packages/core/src/card-text.ts b/packages/core/src/card-text.ts
index 0268423..c60f5b2 100644
--- a/packages/core/src/card-text.ts
+++ b/packages/core/src/card-text.ts
@@ -56,6 +56,7 @@ export function cardTextSlots(card: CardData): TextSlot[] {
     if (item) add(`/footer/${side}/text`, item.text, 'sans400', 12, half - (item.icon ? 13 + 6 : 0));
   }
 
-  add('/cta/label', card.cta?.label, 'sans500', 13, PANEL - 2 * 12 - 15); // px-3 link, 15px arrow
+  // px-3 tile; a linked CTA also shows a 15px arrow.
+  add('/cta/label', card.cta?.label, 'sans500', 13, PANEL - 2 * 12 - (card.cta?.href ? 15 : 0));
   return slots;
 }
diff --git a/packages/core/src/samples/index.ts b/packages/core/src/samples/index.ts
index bfe83f7..e2068b5 100644
--- a/packages/core/src/samples/index.ts
+++ b/packages/core/src/samples/index.ts
@@ -49,7 +49,7 @@ export const commerceApi: DiagramDraft = {
         ],
         statsNote: '2 replication links',
         footer: { left: { text: 'EU West', icon: 'region' }, right: { text: '3 members', icon: 'members' } },
-        cta: { label: 'Open cluster' },
+        cta: { label: 'Open cluster', href: 'https://console.example.com/clusters/orders' },
       },
     },
     {
@@ -65,7 +65,7 @@ export const commerceApi: DiagramDraft = {
         ],
         statsNote: '3 replication links',
         footer: { left: { text: 'EU West', icon: 'region' }, right: { text: '6 members', icon: 'members' } },
-        cta: { label: 'Open cluster' },
+        cta: { label: 'Open cluster', href: 'https://console.example.com/clusters/sessions' },
       },
     },
   ],
diff --git a/packages/core/test/card-text.test.ts b/packages/core/test/card-text.test.ts
index 825ebfe..868f763 100644
--- a/packages/core/test/card-text.test.ts
+++ b/packages/core/test/card-text.test.ts
@@ -44,7 +44,8 @@ describe('cardTextSlots', () => {
     expect(slot(card, '/footer/right/text')!.maxWidth).toBe(118);
   });
 
-  it('the CTA label leaves room for its arrow', () => {
-    expect(slot({ title: 't', cta: { label: 'Open cluster' } }, '/cta/label')).toMatchObject({ face: 'sans500', size: 13, maxWidth: 217 });
+  it('a linked CTA label leaves room for its arrow; an unlinked one (no arrow) gets it back', () => {
+    expect(slot({ title: 't', cta: { label: 'Open', href: 'https://x.dev' } }, '/cta/label')).toMatchObject({ face: 'sans500', size: 13, maxWidth: 217 });
+    expect(slot({ title: 't', cta: { label: 'Open' } }, '/cta/label')).toMatchObject({ maxWidth: 232 });
   });
 });
diff --git a/packages/schema/test/validate.test.ts b/packages/schema/test/validate.test.ts
index 27664a6..9f45c3a 100644
--- a/packages/schema/test/validate.test.ts
+++ b/packages/schema/test/validate.test.ts
@@ -115,6 +115,15 @@ describe('validateDiagram', () => {
       expect(id!.allowedFixes).toEqual([expect.stringMatching(/^remove "id"/)]);
     });
 
+    it('an edge label limit counts characters, not UTF-16 units (emoji)', () => {
+      const emoji = '🚀'.repeat(13); // 13 characters, 26 UTF-16 units
+      expect(diags(base({ edges: [{ id: 'ab', from: 'a', to: 'b', label: emoji }] }))).toEqual([]);
+      expect(diags(base({ edges: [{ id: 'ab', from: 'a', to: 'b', label: '🚀'.repeat(25) }] }))[0]).toMatchObject({
+        subject: '/edges/0/label',
+        allowedFixes: ['shorten "label" to at most 24 characters'],
+      });
+    });
+
     it('limits say how far to cut', () => {
       const stats = Array.from({ length: 4 }, (_, i) => ({ value: String(i), label: 'x' }));
       expect(diags(base({ nodes: [node('a', { card: { title: 'a', stats } })] }))[0]).toMatchObject({
diff --git a/packages/viewer/e2e/explore.spec.ts b/packages/viewer/e2e/explore.spec.ts
index 9abbb75..78354bc 100644
--- a/packages/viewer/e2e/explore.spec.ts
+++ b/packages/viewer/e2e/explore.spec.ts
@@ -303,3 +303,56 @@ test('a view fits its members clear of the toolbar and zoom bar', async ({ page
     }
   }
 });
+
+test('holding an arrow key pans the full distance for every repeat', async ({ page }) => {
+  const start = await viewportOf(page);
+  await page.locator('.sm-stage').focus();
+  await page.keyboard.down('ArrowRight');
+  for (let i = 0; i < 4; i++) await page.keyboard.down('ArrowRight'); // auto-repeat
+  await page.keyboard.up('ArrowRight');
+  await settle(page);
+  expect((await viewportOf(page)).x).toBeCloseTo(start.x - 5 * 80, 0);
+});
+
+test('dragging on the minimap pans the canvas with the pointer', async ({ page }) => {
+  await page.getByRole('button', { name: 'Toggle minimap' }).click();
+  const map = (await page.locator('svg.sm-minimap').boundingBox())!;
+  const before = await viewportOf(page);
+  await page.mouse.move(map.x + map.width * 0.3, map.y + map.height / 2);
+  await page.mouse.down();
+  await page.mouse.move(map.x + map.width * 0.7, map.y + map.height / 2, { steps: 6 });
+  const mid = await viewportOf(page);
+  await page.mouse.up();
+  expect(mid.x).toBeLessThan(before.x - 50); // moved during the drag, not only on release
+  expect(mid.k).toBeCloseTo(before.k, 5);
+});
+
+test('the canvas neither selects text nor scrolls the page on touch', async ({ page }) => {
+  const style = await page.locator('.sm-stage').evaluate((el) => {
+    const s = getComputedStyle(el);
+    return { select: s.userSelect, touch: s.touchAction };
+  });
+  expect(style).toEqual({ select: 'none', touch: 'none' });
+});
+
+test('a canvas that mounts at zero size fits once it gets one, without errors', async ({ page }) => {
+  const errors: string[] = [];
+  page.on('console', (m) => m.type() === 'error' && errors.push(m.text()));
+  // A constructed sheet survives document parsing (a <style> added this early doesn't).
+  await page.addInitScript(() => {
+    const sheet = new CSSStyleSheet();
+    sheet.replaceSync('section[aria-label="Diagram"] { height: 0 !important; flex: none !important; }');
+    document.adoptedStyleSheets = [sheet];
+  });
+  await page.goto('/?page=sample');
+  await expect(page.locator('.sm-card')).toHaveCount(6);
+  expect((await page.locator('.sm-stage').boundingBox())!.height).toBe(0);
+  await page.evaluate(() => (document.adoptedStyleSheets = []));
+  await settle(page);
+  const stage = (await page.locator('.sm-stage').boundingBox())!;
+  for (const id of ['edge', 'orders', 'commerce-api-3']) {
+    const c = (await card(page, id).boundingBox())!;
+    expect(c.x >= stage.x && c.y >= stage.y && c.x + c.width <= stage.x + stage.width && c.y + c.height <= stage.y + stage.height, id).toBe(true);
+  }
+  expect(errors).toEqual([]); // a zero-size zoom animation used to render NaN transforms
+});
diff --git a/packages/viewer/src/canvas/DiagramCanvas.tsx b/packages/viewer/src/canvas/DiagramCanvas.tsx
index bdd5325..8597b2b 100644
--- a/packages/viewer/src/canvas/DiagramCanvas.tsx
+++ b/packages/viewer/src/canvas/DiagramCanvas.tsx
@@ -21,19 +21,19 @@ function union(rects: Rect[]): Rect | null {
 }
 
 // Camera follows the explorer: a view fits its members (Overview fits everything, Q27); a revealing
-// selection (search, deep link) centres the node. Skips the first run for Overview so the initial fit stands.
+// selection (search, deep link) centres the node. The initial Overview needs nothing: useZoom already fit it.
 function useCameraEffects(scene: Scene, camera: Camera, restored: boolean) {
   const { draft, state } = useExplore();
   const rectOf = useMemo(() => new Map(scene.cards.map((c) => [c.node.id, c.rect])), [scene]);
-  const first = useRef(true);
+  // Compare against the previous view, not a "first run" flag: StrictMode re-runs effects on mount.
+  const shownView = useRef<string | null | undefined>(restored ? state.view : null);
   useEffect(() => {
-    // After a live reload the restored camera stands; later view changes move it as usual.
-    if (first.current && restored) return void (first.current = false);
+    if (shownView.current === state.view) return;
+    shownView.current = state.view;
     const members = state.view ? (draft.views?.find((v) => v.id === state.view)?.nodes ?? []) : [];
     const box = union(members.flatMap((id) => rectOf.get(id) ?? []));
     if (box) camera.fitRect(box);
-    else if (!first.current) camera.fit();
-    first.current = false;
+    else camera.fit();
   }, [state.view, draft, rectOf, camera]);
   // The reveal a live reload restores from the hash is already on screen.
   const restoredReveal = useRef(restored ? state.reveal : -1);
@@ -99,7 +99,7 @@ export function DiagramCanvas({ diagram, children }: { diagram: LaidOutDiagram;
       ArrowLeft: [PAN_STEP, 0],
       ArrowRight: [-PAN_STEP, 0],
     };
-    if (pan[e.key]) camera.panBy(...pan[e.key]!);
+    if (pan[e.key]) camera.panBy(...pan[e.key]!, { instant: e.repeat });
     else if (e.key === '+' || e.key === '=') camera.zoomIn();
     else if (e.key === '-') camera.zoomOut();
     else if (e.key === '0') camera.fit();
diff --git a/packages/viewer/src/canvas/Minimap.tsx b/packages/viewer/src/canvas/Minimap.tsx
index 222792c..77eb416 100644
--- a/packages/viewer/src/canvas/Minimap.tsx
+++ b/packages/viewer/src/canvas/Minimap.tsx
@@ -1,4 +1,4 @@
-import type { MouseEvent } from 'react';
+import { useRef, type PointerEvent } from 'react';
 import type { Rect } from '@stackmap/core';
 import { PANEL_CLASS, PANEL_STYLE } from '../chrome/ui';
 import type { Scene } from './scene';
@@ -26,24 +26,39 @@ export function Minimap({ scene }: { scene: Scene }) {
     height: Math.max(box.y + box.height, view.y + view.height) - y0,
   };
 
-  const onClick = (e: MouseEvent<SVGSVGElement>) => {
+  // Press to jump there; keep the button down and drag to steer the canvas live.
+  const dragging = useRef(false);
+  const toDiagram = (e: PointerEvent<SVGSVGElement>) => {
     const ctm = e.currentTarget.getScreenCTM();
-    if (!ctm) return;
-    const p = new DOMPoint(e.clientX, e.clientY).matrixTransform(ctm.inverse());
+    return ctm && new DOMPoint(e.clientX, e.clientY).matrixTransform(ctm.inverse());
+  };
+  const onPointerDown = (e: PointerEvent<SVGSVGElement>) => {
+    const p = toDiagram(e);
+    if (!p) return;
+    dragging.current = true;
+    e.currentTarget.setPointerCapture(e.pointerId);
     centerOn({ x: p.x, y: p.y });
   };
+  const onPointerMove = (e: PointerEvent<SVGSVGElement>) => {
+    const p = dragging.current && toDiagram(e);
+    if (p) centerOn({ x: p.x, y: p.y }, { instant: true });
+  };
+  const stop = () => void (dragging.current = false);
 
   return (
     <div className={`${PANEL_CLASS} p-1.5`} style={PANEL_STYLE}>
       <svg
         role="img"
         aria-label="Minimap"
-        className="sm-minimap block cursor-pointer overflow-visible"
+        className="sm-minimap block cursor-pointer overflow-visible touch-none select-none"
         width={WIDTH}
         height={height}
         viewBox={`${frame.x} ${frame.y} ${frame.width} ${frame.height}`}
         preserveAspectRatio="xMidYMid meet"
-        onClick={onClick}
+        onPointerDown={onPointerDown}
+        onPointerMove={onPointerMove}
+        onPointerUp={stop}
+        onPointerCancel={stop}
       >
         {scene.frames.map((f) => (
           <rect
diff --git a/packages/viewer/src/canvas/useZoom.ts b/packages/viewer/src/canvas/useZoom.ts
index 7d92ffc..2fd8975 100644
--- a/packages/viewer/src/canvas/useZoom.ts
+++ b/packages/viewer/src/canvas/useZoom.ts
@@ -7,14 +7,19 @@ import { clearStoredViewport, readStoredViewport } from '../live';
 import { CHROME_INSET, fitTransform, MAX_ZOOM, MIN_ZOOM, viewportRect, ZOOM_STEP, type Size, type Transform } from './viewport';
 
 /** Camera moves. Stable across renders, so consumers don't re-render on every pan/zoom frame. */
+/** `instant` skips the animation: drags and key auto-repeat would otherwise interrupt it every frame. */
+export interface MoveOptions {
+  instant?: boolean;
+}
+
 export interface Camera {
   zoomIn(): void;
   zoomOut(): void;
   fit(): void;
-  centerOn(p: Point): void;
+  centerOn(p: Point, opts?: MoveOptions): void;
   /** Fit an arbitrary diagram-space rect (e.g. a view's members), never zooming past 100%. */
   fitRect(r: Rect): void;
-  panBy(dx: number, dy: number): void;
+  panBy(dx: number, dy: number, opts?: MoveOptions): void;
   /** Pan the least distance that brings `r` fully on stage; no-op when it already is. */
   ensureVisible(r: Rect): void;
 }
@@ -27,13 +32,15 @@ export interface ViewportApi extends Camera {
   restored: boolean;
 }
 
-const duration = () => (matchMedia('(prefers-reduced-motion: reduce)').matches ? 0 : 150);
+const duration = (opts?: MoveOptions) => (opts?.instant || matchMedia('(prefers-reduced-motion: reduce)').matches ? 0 : 150);
 const toZoom = (t: Transform) => zoomIdentity.translate(t.x, t.y).scale(t.k);
 
 export function useZoom(stageRef: RefObject<HTMLDivElement | null>, content: Rect): ViewportApi {
   const [transform, setTransform] = useState<Transform>({ x: 0, y: 0, k: 1 });
   const current = useRef(transform);
   current.current = transform;
+  // Where an animated pan is heading, so a press during the animation adds to it instead of losing the rest.
+  const pending = useRef<Transform | null>(null);
   const [stage, setStage] = useState<Size>({ width: 0, height: 0 });
   const behavior = useRef<ZoomBehavior<HTMLDivElement, unknown> | null>(null);
   // Read once per mount; `stackmap serve` stores the camera right before it reloads the page.
@@ -46,6 +53,7 @@ export function useZoom(stageRef: RefObject<HTMLDivElement | null>, content: Rec
     const z = zoom<HTMLDivElement, unknown>()
       .scaleExtent([MIN_ZOOM, MAX_ZOOM])
       .on('zoom', (event: D3ZoomEvent<HTMLDivElement, unknown>) => {
+        if (event.sourceEvent) pending.current = null; // the user took over
         const { x, y, k } = event.transform;
         setTransform({ x, y, k });
       });
@@ -57,11 +65,20 @@ export function useZoom(stageRef: RefObject<HTMLDivElement | null>, content: Rec
     setStage(size);
     sel.call(z.transform, toZoom(stored ?? fitTransform(content, size, { inset: CHROME_INSET })));
     if (stored) clearStoredViewport();
+    // A stage that mounts hidden or collapsed has no size to fit to; fit on its first real one instead.
+    let fitted = stored !== null || (size.width > 0 && size.height > 0);
 
     const observer =
       typeof ResizeObserver === 'undefined'
         ? null
-        : new ResizeObserver(() => setStage({ width: el.clientWidth, height: el.clientHeight }));
+        : new ResizeObserver(() => {
+            const next = { width: el.clientWidth, height: el.clientHeight };
+            setStage(next);
+            if (!fitted && next.width > 0 && next.height > 0) {
+              fitted = true;
+              sel.call(z.transform, toZoom(fitTransform(content, next, { inset: CHROME_INSET })));
+            }
+          });
     observer?.observe(el);
     return () => {
       observer?.disconnect();
@@ -74,7 +91,8 @@ export function useZoom(stageRef: RefObject<HTMLDivElement | null>, content: Rec
     (apply: (z: ZoomBehavior<HTMLDivElement, unknown>, el: HTMLDivElement) => void) => {
       const el = stageRef.current;
       const z = behavior.current;
-      if (el && z) apply(z, el);
+      // A 0×0 stage has nothing to show, and d3's zoom interpolation divides by its size (NaN transform).
+      if (el && z && el.clientWidth > 0 && el.clientHeight > 0) apply(z, el);
     },
     [stageRef],
   );
@@ -99,10 +117,13 @@ export function useZoom(stageRef: RefObject<HTMLDivElement | null>, content: Rec
   );
   // Centre between the chrome bands, not on the raw stage, so the node doesn't sit under the toolbar.
   const centerOn = useCallback(
-    (p: Point) =>
+    (p: Point, opts?: MoveOptions) =>
       animate((z, el) => {
         const anchor: [number, number] = [el.clientWidth / 2, (el.clientHeight + CHROME_INSET.top - CHROME_INSET.bottom) / 2];
-        select(el).transition().duration(duration()).call(z.translateTo, p.x, p.y, anchor);
+        pending.current = null;
+        // A 0ms transition still lands a frame later, so rapid instant moves would cancel each other.
+        if (opts?.instant) select(el).interrupt().call(z.translateTo, p.x, p.y, anchor);
+        else select(el).transition().duration(duration()).call(z.translateTo, p.x, p.y, anchor);
       }),
     [animate],
   );
@@ -123,8 +144,24 @@ export function useZoom(stageRef: RefObject<HTMLDivElement | null>, content: Rec
     [animate],
   );
   const panBy = useCallback(
-    (dx: number, dy: number) =>
-      animate((z, el) => select(el).transition().duration(duration()).call(z.translateBy, dx / current.current.k, dy / current.current.k)),
+    (dx: number, dy: number, opts?: MoveOptions) =>
+      animate((z, el) => {
+        const base = pending.current ?? current.current;
+        const next = { x: base.x + dx, y: base.y + dy, k: base.k };
+        if (duration(opts) === 0) {
+          pending.current = null;
+          select(el).interrupt().call(z.transform, toZoom(next));
+          return;
+        }
+        pending.current = next;
+        select(el)
+          .transition()
+          .duration(duration())
+          .call(z.transform, toZoom(next))
+          .on('end', () => {
+            if (pending.current === next) pending.current = null;
+          });
+      }),
     [animate],
   );
   const ensureVisible = useCallback(
diff --git a/packages/viewer/src/card/NodeCard.test.tsx b/packages/viewer/src/card/NodeCard.test.tsx
index b5091a5..1d53d7a 100644
--- a/packages/viewer/src/card/NodeCard.test.tsx
+++ b/packages/viewer/src/card/NodeCard.test.tsx
@@ -91,4 +91,21 @@ describe('NodeCard', () => {
     expect(link).toHaveAttribute('target', '_blank');
     expect(link).toHaveAttribute('rel', 'noreferrer');
   });
+
+  it('a CTA without href is plain text, not a link-looking button', () => {
+    const { container } = render(<NodeCard node={{ id: 'n', type: 'database', card: { title: 'Orders', cta: { label: 'Open cluster' } } }} />);
+    const cta = container.querySelector('[data-testid="card-cta"]')!;
+    expect(cta.querySelector('a')).toBeNull();
+    expect(cta.querySelector('svg')).toBeNull(); // no arrow promising navigation
+    expect(cta.textContent).toBe('Open cluster');
+  });
+
+  it('a CTA with href is a link that opens in a new tab', () => {
+    const { container } = render(
+      <NodeCard node={{ id: 'n', type: 'database', card: { title: 'Orders', cta: { label: 'Open cluster', href: 'https://example.com' } } }} />,
+    );
+    const a = container.querySelector('[data-testid="card-cta"] a')!;
+    expect(a).toHaveAttribute('href', 'https://example.com');
+    expect(a).toHaveAttribute('rel', 'noreferrer');
+  });
 });
diff --git a/packages/viewer/src/card/NodeCard.tsx b/packages/viewer/src/card/NodeCard.tsx
index 394a430..cf99586 100644
--- a/packages/viewer/src/card/NodeCard.tsx
+++ b/packages/viewer/src/card/NodeCard.tsx
@@ -121,20 +121,29 @@ export function NodeCard({ node }: { node: DiagramNode }) {
 
       {card.cta && (
         <div data-testid="card-cta" className="shrink-0 px-3" style={{ height: CARD.cta }}>
-          <a
-            href={card.cta.href}
-            // Not a tab stop inside the card (nested interactive); the inspector repeats the link.
-            tabIndex={-1}
-            target="_blank"
-            rel="noreferrer"
-            className="flex h-9 items-center justify-between rounded-lg px-3 text-[13px] font-medium text-fg"
-            style={{ background: tint('tile') }}
-          >
-            <span className="truncate" title={card.cta.label}>
-              {card.cta.label}
-            </span>
-            <ArrowUpRight size={15} strokeWidth={1.75} aria-hidden="true" style={{ color: tint('accent') }} />
-          </a>
+          {card.cta.href ? (
+            <a
+              href={card.cta.href}
+              // Not a tab stop inside the card (nested interactive); the inspector repeats the link.
+              tabIndex={-1}
+              target="_blank"
+              rel="noreferrer"
+              className="flex h-9 items-center justify-between rounded-lg px-3 text-[13px] font-medium text-fg"
+              style={{ background: tint('tile') }}
+            >
+              <span className="truncate" title={card.cta.label}>
+                {card.cta.label}
+              </span>
+              <ArrowUpRight size={15} strokeWidth={1.75} aria-hidden="true" style={{ color: tint('accent') }} />
+            </a>
+          ) : (
+            // No link: same tile, but no arrow promising navigation that isn't there.
+            <div className="flex h-9 items-center rounded-lg px-3 text-[13px] font-medium text-fg" style={{ background: tint('tile') }}>
+              <span className="truncate" title={card.cta.label}>
+                {card.cta.label}
+              </span>
+            </div>
+          )}
         </div>
       )}
     </div>
diff --git a/packages/viewer/src/chrome/export.test.ts b/packages/viewer/src/chrome/export.test.ts
index f2951c5..909a8fb 100644
--- a/packages/viewer/src/chrome/export.test.ts
+++ b/packages/viewer/src/chrome/export.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest';
-import { CANVAS_MAX, effectiveScale, exportFileName } from './export';
+import { CANVAS_AREA_MAX, CANVAS_MAX, effectiveScale, exportFileName } from './export';
 
 describe('export', () => {
   it('keeps the requested scale while the canvas fits', () => {
@@ -8,9 +8,18 @@ describe('export', () => {
   });
 
   it('scales down so the longest side stays within the browser canvas limit', () => {
-    expect(effectiveScale(2344, 18636, 1)).toBeCloseTo(CANVAS_MAX / 18636, 6);
-    expect(effectiveScale(2344, 18636, 2)).toBeCloseTo(CANVAS_MAX / 18636, 6);
-    expect(effectiveScale(10000, 500, 2) * 10000).toBeLessThanOrEqual(CANVAS_MAX);
+    for (const [w, h, scale] of [[2344, 18636, 1], [2344, 18636, 2], [10000, 500, 2]] as const) {
+      const s = effectiveScale(w, h, scale);
+      expect(Math.max(w, h) * s).toBeLessThanOrEqual(CANVAS_MAX);
+      expect(w * s * h * s).toBeLessThanOrEqual(CANVAS_AREA_MAX + 1e-6);
+      expect(s).toBeLessThan(scale);
+    }
+  });
+
+  it("also stays within WebKit's canvas area limit (~16.7 Mpx)", () => {
+    const s = effectiveScale(6000, 6000, 2);
+    expect(6000 * s * (6000 * s)).toBeLessThanOrEqual(CANVAS_AREA_MAX);
+    expect(effectiveScale(1000, 800, 2)).toBe(2);
   });
 
   it('names files after the title', () => {
diff --git a/packages/viewer/src/chrome/export.ts b/packages/viewer/src/chrome/export.ts
index 1d51e0c..fef197a 100644
--- a/packages/viewer/src/chrome/export.ts
+++ b/packages/viewer/src/chrome/export.ts
@@ -14,9 +14,12 @@ export const exportFileName = (title: string, ext: string) =>
       .replace(/^-|-$/g, '') || 'diagram'
   }.${ext}`;
 
-/** The requested scale, or less when the canvas would pass CANVAS_MAX on its longest side. */
+/** Canvas area Safari/WebKit renders; past it the canvas silently comes out blank. */
+export const CANVAS_AREA_MAX = 16_777_216;
+
+/** The requested scale, or less when the canvas would pass either browser limit. */
 export const effectiveScale = (width: number, height: number, scale: number) =>
-  Math.min(scale, CANVAS_MAX / Math.max(width, height));
+  Math.min(scale, CANVAS_MAX / Math.max(width, height), Math.sqrt(CANVAS_AREA_MAX / (width * height)));
 
 // Only properties that change how a card, frame or edge looks. Copying every computed property
 // inline made a 6-card SVG 1.4 MB (a 500-node one ~90 MB).
diff --git a/packages/viewer/src/pages/gallery-nodes.ts b/packages/viewer/src/pages/gallery-nodes.ts
index 05a5542..b4eabd9 100644
--- a/packages/viewer/src/pages/gallery-nodes.ts
+++ b/packages/viewer/src/pages/gallery-nodes.ts
@@ -29,7 +29,7 @@ const rich = (type: NodeType): DiagramNode => {
         : undefined,
       statsNote: clustered ? '2 replication links' : undefined,
       footer: { left: { text: 'EU West', icon: 'region' }, right: { text: clustered ? '3 members' : 'Stateless' } },
-      cta: clustered ? { label: 'Open cluster' } : undefined,
+      cta: clustered ? { label: 'Open cluster', href: `https://console.example.com/clusters/${type}` } : undefined,
     },
   };
 };
diff --git a/packages/viewer/src/samples/commerce-api.layout.ts b/packages/viewer/src/samples/commerce-api.layout.ts
index 37d5114..500529d 100644
--- a/packages/viewer/src/samples/commerce-api.layout.ts
+++ b/packages/viewer/src/samples/commerce-api.layout.ts
@@ -147,7 +147,8 @@ export const commerceApiLayout: LaidOutDiagram = {
             }
           },
           "cta": {
-            "label": "Open cluster"
+            "label": "Open cluster",
+            "href": "https://console.example.com/clusters/orders"
           }
         }
       },
@@ -180,7 +181,8 @@ export const commerceApiLayout: LaidOutDiagram = {
             }
           },
           "cta": {
-            "label": "Open cluster"
+            "label": "Open cluster",
+            "href": "https://console.example.com/clusters/sessions"
           }
         }
       }
diff --git a/packages/viewer/src/styles.css b/packages/viewer/src/styles.css
index c885dbe..7fda241 100644
--- a/packages/viewer/src/styles.css
+++ b/packages/viewer/src/styles.css
@@ -37,6 +37,13 @@ body {
   border: 1.5px solid var(--sm-handle);
 }
 
+/* The canvas is a drag surface: no text selection on drag, no page scroll/zoom on touch (d3-zoom owns it). */
+.sm-stage {
+  user-select: none;
+  -webkit-user-select: none;
+  touch-action: none;
+}
+
 /* Explorer emphasis (M3). Opacity only: layout never changes in the viewer. */
 .sm-card,
 .sm-edge-path,