diff --git a/apps/storybook/stories/Review3935.stories.tsx b/apps/storybook/stories/Review3935.stories.tsx
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+// Temporary review harness for PR #3935. Not committed.
+import type {Meta, StoryObj} from '@storybook/react';
+import * as stylex from '@stylexjs/stylex';
+import {HStack, Stack, VStack} from '@astryxdesign/core/Layout';
+import {colorVars, spacingVars} from '@astryxdesign/core/theme/tokens.stylex';
+
+const styles = stylex.create({
+  page: {
+    display: 'grid',
+    gridTemplateColumns: 'repeat(2, minmax(0, 1fr))',
+    gap: spacingVars['--spacing-4'],
+    padding: spacingVars['--spacing-4'],
+    backgroundColor: colorVars['--color-background-body'],
+    color: colorVars['--color-text-primary'],
+  },
+  pane: {
+    height: 280,
+    overflow: 'auto',
+    borderWidth: 1,
+    borderStyle: 'solid',
+    borderColor: colorVars['--color-border'],
+    backgroundColor: colorVars['--color-background-card'],
+  },
+  columns: {
+    display: 'grid',
+    gridTemplateColumns: 'minmax(0, 1fr) 150px',
+    alignItems: 'stretch',
+    gap: spacingVars['--spacing-3'],
+    padding: spacingVars['--spacing-2'],
+  },
+  legacySticky: {
+    position: 'sticky',
+    insetBlockStart: spacingVars['--spacing-8'],
+    alignSelf: 'flex-start',
+  },
+  panel: {
+    backgroundColor: colorVars['--color-background-blue'],
+    color: colorVars['--color-text-blue'],
+    borderWidth: 1,
+    borderStyle: 'solid',
+    borderColor: colorVars['--color-border-blue'],
+    padding: spacingVars['--spacing-3'],
+  },
+  tall: {
+    minHeight: 760,
+  },
+  block: {
+    minHeight: 100,
+    borderBottomWidth: 1,
+    borderBottomStyle: 'solid',
+    borderBottomColor: colorVars['--color-border'],
+    padding: spacingVars['--spacing-2'],
+  },
+  columnPane: {
+    display: 'flex',
+    flexDirection: 'column',
+    alignItems: 'stretch',
+    inlineSize: 320,
+    height: 260,
+    overflow: 'auto',
+    borderWidth: 1,
+    borderStyle: 'solid',
+    borderColor: colorVars['--color-border'],
+    padding: spacingVars['--spacing-2'],
+  },
+  fullWidth: {
+    inlineSize: '100%',
+  },
+  stretchSelf: {
+    alignSelf: 'stretch',
+  },
+  zoom200: {
+    fontSize: '200%',
+  },
+});
+
+function TallContent() {
+  return (
+    <VStack xstyle={styles.tall}>
+      {Array.from({length: 7}, (_, index) => (
+        <div key={index} {...stylex.props(styles.block)}>Scrollable neighbour {index + 1}</div>
+      ))}
+    </VStack>
+  );
+}
+
+function Comparison({legacy}: {legacy: boolean}) {
+  const label = legacy ? 'legacy' : 'new';
+  return (
+    <div data-review-pr3935={label} data-scroll-pane {...stylex.props(styles.pane)}>
+      <div {...stylex.props(styles.columns)}>
+        <TallContent />
+        <VStack
+          data-sticky-subject
+          gap={2}
+          stickyOffset={legacy ? undefined : 8}
+          isSticky={legacy ? undefined : true}
+          xstyle={[styles.panel, legacy && styles.legacySticky]}>
+          <strong>Sticky product info</strong>
+          <button type="button">Focusable action</button>
+        </VStack>
+      </div>
+    </div>
+  );
+}
+
+const meta: Meta = {title: 'Review/PR3935'};
+export default meta;
+type Story = StoryObj;
+
+export const LegacyWorkaround: Story = {render: () => <Comparison legacy />};
+export const NewProps: Story = {render: () => <Comparison legacy={false} />};
+
+export const Zoom200: Story = {
+  render: () => (
+    <div {...stylex.props(styles.zoom200)}>
+      <Comparison legacy={false} />
+    </div>
+  ),
+};
+
+export const ColumnOverride: Story = {
+  render: () => (
+    <div data-review-pr3935="override" data-column-override-pane {...stylex.props(styles.columnPane)}>
+      <HStack
+        data-column-override-sticky
+        isSticky
+        stickyOffset={2}
+        xstyle={[styles.panel, styles.stretchSelf]}>
+        <button type="button">Full-width sticky header</button>
+      </HStack>
+      <TallContent />
+    </div>
+  ),
+};
+
+export const ConstrainedMatrix: Story = {
+  render: () => (
+    <div data-review-pr3935="matrix" {...stylex.props(styles.page)}>
+      <section>
+        <h3>Column flex parent</h3>
+        <div data-column-pane {...stylex.props(styles.columnPane)}>
+          <Stack data-column-baseline xstyle={styles.panel}>Baseline full-width header</Stack>
+          <HStack data-column-sticky isSticky stickyOffset={2} xstyle={styles.panel}>
+            <button type="button">Sticky header action</button>
+          </HStack>
+          <TallContent />
+        </div>
+      </section>
+      <section dir="rtl">
+        <h3>RTL grid rail</h3>
+        <div data-rtl-pane {...stylex.props(styles.pane)}>
+          <div {...stylex.props(styles.columns)}>
+            <TallContent />
+            <VStack data-rtl-sticky isSticky stickyOffset={2} xstyle={styles.panel}>
+              <button type="button">إجراء ثابت</button>
+            </VStack>
+          </div>
+        </div>
+      </section>
+    </div>
+  ),
+};