diff --git a/tests/e2e/tool-preview.test.ts b/tests/e2e/tool-preview.test.ts
index 0a0672a..28c2c0d 100644
--- a/tests/e2e/tool-preview.test.ts
+++ b/tests/e2e/tool-preview.test.ts
@@ -13,6 +13,76 @@ let page: Page;
 let fixture: string;
 const errors: string[] = [];
 
+async function resizeWindow(width: number, height: number) {
+  const window = await app.browserWindow(page);
+  await window.evaluate(
+    (window, { width, height }) => window.setContentSize(width, height),
+    { width, height },
+  );
+  // macOS can clamp a requested window to the display's available work area.
+  const [actualWidth, actualHeight] = await window.evaluate((window) => window.getContentSize());
+  // Device-metrics emulation can make DOM bounds disagree with captured layers.
+  // Resize the real window and verify the renderer follows its content bounds.
+  await page.waitForFunction(
+    ({ width, height }) => innerWidth === width && innerHeight === height,
+    { width: actualWidth, height: actualHeight },
+  );
+  expect(actualWidth).toBeGreaterThanOrEqual(900);
+  expect(actualHeight).toBeGreaterThanOrEqual(600);
+}
+
+// DOM bounds alone cannot detect a stale compositor layer in a screenshot.
+// Inspect the captured pixels where the footer label is meant to be painted.
+async function footerPaint(screenshot: Buffer) {
+  const label = await page.getByRole('button', { name: 'Fork from here', exact: true }).evaluate((button) => {
+    const { x, y, width, height } = button.getBoundingClientRect();
+    return {
+      x, y, width, height, colour: getComputedStyle(button).color,
+      hitTarget: button.contains(document.elementFromPoint(x + width / 2, y + height / 2)),
+    };
+  });
+  return app.evaluate(({ nativeImage }, { png, label }) => {
+    const image = nativeImage.createFromBuffer(Buffer.from(png, 'base64'));
+    const size = image.getSize();
+    const bitmap = image.toBitmap();
+    const colour = label.colour.match(/[\d.]+/g)!.slice(0, 3).map(Number);
+    let textPixels = 0;
+    for (let y = Math.ceil(label.y + 5); y < Math.min(size.height, label.y + label.height - 5); y++) {
+      for (let x = Math.ceil(label.x + 20); x < Math.min(size.width, label.x + label.width - 20); x++) {
+        const offset = (y * size.width + x) * 4;
+        // Electron's bitmap is BGRA. Allow antialiasing at glyph edges.
+        if (colour.every((value, channel) => Math.abs(value - bitmap[offset + 2 - channel]) < 20)) textPixels++;
+      }
+    }
+    return { size, label, textPixels };
+  }, { png: screenshot.toString('base64'), label });
+}
+
+async function captureFooter(name: string) {
+  const footer = page.getByRole('button', { name: 'Fork from here', exact: true });
+  // Wait for virtual-row measurement after expansion, collapse or resizing.
+  await expect.poll(async () => {
+    const card = await page.locator('.wb-tool').boundingBox();
+    const button = await footer.boundingBox();
+    return !!card && !!button && button.y >= card.y + card.height;
+  }).toBe(true);
+  await footer.scrollIntoViewIfNeeded();
+  const screenshot = await page.screenshot({ scale: 'css' });
+  const paint = await footerPaint(screenshot);
+  const window = await app.browserWindow(page);
+  const nativeSize = await window.evaluate((window) => window.getContentSize());
+  const viewport = await page.evaluate(() => ({ width: innerWidth, height: innerHeight }));
+  await Promise.all([
+    fs.writeFile(path.join(root, '.tmp/proof', `${name}.png`), screenshot),
+    fs.writeFile(path.join(shots, `${name}.png`), screenshot),
+    fs.writeFile(path.join(shots, `${name}.json`), JSON.stringify({ ...paint, nativeSize, viewport }, null, 2)),
+  ]);
+  expect([viewport.width, viewport.height]).toEqual(nativeSize);
+  expect(paint.size).toEqual(viewport);
+  expect(paint.label.hitTarget).toBe(true);
+  expect(paint.textPixels, `Footer label is missing from ${name}.png`).toBeGreaterThan(8);
+}
+
 describe('bounded tool previews in Electron', () => {
   beforeAll(async () => {
     fixture = await fs.mkdtemp(path.join(os.tmpdir(), 'pidex-tool-preview-'));
@@ -61,7 +131,7 @@ describe('bounded tool previews in Electron', () => {
     page.setDefaultTimeout(10_000);
     page.on('pageerror', (error) => errors.push(error.message));
     await page.getByRole('heading', { name: 'Start a session', exact: true }).waitFor();
-    await page.setViewportSize({ width: 1280, height: 1100 });
+    await resizeWindow(1280, 1100);
     await page.evaluate(() => document.fonts.ready);
     await page.getByRole('button', { name: /^Sessions/ }).click();
   });
@@ -71,7 +141,7 @@ describe('bounded tool previews in Electron', () => {
     if (fixture) await fs.rm(fixture, { recursive: true, force: true });
   });
 
-  it.each(['write', 'edit'])('bounds a long %s line, copies the full input and expands on request', async (tool) => {
+  it.each(['write', 'edit'])('bounds a long %s line and keeps the footer painted through native window resizing', async (tool) => {
     await page.getByRole('tree', { name: 'Session archives', exact: true })
       .getByRole('treeitem', { name: new RegExp(`Inspect long ${tool} input`) }).click();
     const card = page.locator('.wb-tool');
@@ -94,26 +164,18 @@ describe('bounded tool previews in Electron', () => {
     await card.getByRole('button', { name: 'Show less' }).click();
     expect((await diff.textContent())?.length).toBe(2000);
     await card.locator('summary').scrollIntoViewIfNeeded();
-    // Expansion changes the virtual row height. Wait for measurement before
-    // capturing so the history footer has moved below the resized card.
-    await page.evaluate(() => new Promise<void>((resolve) => {
-      requestAnimationFrame(() => requestAnimationFrame(() => resolve()));
-    }));
-    await expect.poll(async () => {
-      const outputBounds = await card.getByRole('button', { name: 'Output details' }).boundingBox();
-      const footerBounds = await page.getByRole('button', { name: 'Fork from here', exact: true }).boundingBox();
-      return !!outputBounds && !!footerBounds && footerBounds.y >= outputBounds.y + outputBounds.height;
-    }).toBe(true);
-    const screenshot = `${tool}-bounded-preview.png`;
-    await page.screenshot({ path: path.join(root, '.tmp/proof', screenshot) });
-    await page.screenshot({ path: path.join(shots, screenshot) });
+    await captureFooter(`${tool}-bounded-preview`);
 
-    await page.setViewportSize({ width: 900, height: 600 });
+    await resizeWindow(900, 600);
     await card.getByRole('button', { name: 'Show more' }).scrollIntoViewIfNeeded();
     expect(await page.evaluate(() => document.body.scrollWidth <= window.innerWidth)).toBe(true);
-    await page.screenshot({ path: path.join(root, '.tmp/proof', `${tool}-bounded-narrow.png`) });
-    await page.screenshot({ path: path.join(shots, `${tool}-bounded-narrow.png`) });
-    await page.setViewportSize({ width: 1280, height: 1100 });
+    await page.screenshot({ scale: 'css', path: path.join(root, '.tmp/proof', `${tool}-bounded-narrow.png`) });
+    await page.screenshot({ scale: 'css', path: path.join(shots, `${tool}-bounded-narrow.png`) });
+    await captureFooter(`${tool}-footer-narrow`);
+    await resizeWindow(1280, 1100);
+    await captureFooter(`${tool}-footer-restored`);
+    await card.locator('summary').click();
+    await captureFooter(`${tool}-footer-collapsed`);
     expect(errors).toEqual([]);
   });
 });