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+/**
+ * ObjectUI
+ * Copyright (c) 2024-present ObjectStack Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import { describe, it, expect, vi, beforeAll, afterEach } from 'vitest';
+import { render, fireEvent, cleanup } from '@testing-library/react';
+import type { DetailViewSection } from '@object-ui/types';
+import { DetailSection } from '../DetailSection';
+
+/**
+ * objectstack#26329 — the read-mode copy-to-clipboard button on a copyable,
+ * non-editable field was revealed on HOVER only (`opacity-0
+ * group-hover:opacity-100`). It is a real `<button>`, so a keyboard Tab stop
+ * landed on it while it stayed fully transparent: the focus ring the shared
+ * `Button` draws was painted at opacity 0. The inline-edit pencil beside it had
+ * the same defect and was fixed the same way (objectstack#25883; its pin is
+ * `inlineEditPencil.focusReveal-25883.test.tsx`).
+ *
+ * The copy button must now also show while it, or anything else in its field
+ * (the field's own click-to-copy row is a Tab stop too), has keyboard focus.
+ * Hover behaves exactly as before.
+ *
+ * jsdom has no layout and no CSS engine, so "visible on focus" cannot be
+ * measured here. What these tests pin is the contract a browser turns into
+ * visibility: the copy button is a focusable button, it carries the
+ * focus-reveal utilities next to the unchanged hover reveal, the shared focus
+ * ring is still on it, and the `group` its `group-*` variants resolve against
+ * is its own field. Activation is asserted behaviourally.
+ *
+ * The copy button is found by its icon, not by its localized label, so the
+ * tests hold in every locale.
+ */
+
+const copyButtons = (root: HTMLElement): HTMLButtonElement[] =>
+  Array.from(root.querySelectorAll('svg.lucide-copy')).map(
+    (svg) => svg.closest('button') as HTMLButtonElement,
+  );
+
+function expectFocusRevealContract(copy: HTMLButtonElement) {
+  // A real, enabled, tabbable control: the Tab stop the defect is about.
+  expect(copy.tagName).toBe('BUTTON');
+  expect(copy).not.toBeDisabled();
+  expect(copy.getAttribute('tabindex')).not.toBe('-1');
+  copy.focus();
+  expect(copy).toHaveFocus();
+
+  const cls = copy.classList;
+  // Hidden at rest, revealed on hover: unchanged.
+  expect(cls.contains('opacity-0')).toBe(true);
+  expect(cls.contains('group-hover:opacity-100')).toBe(true);
+  // Revealed on keyboard focus of the copy button itself …
+  expect(cls.contains('focus-visible:opacity-100')).toBe(true);
+  // … and while focus is anywhere inside its field (e.g. its click-to-copy row).
+  expect(cls.contains('group-focus-within:opacity-100')).toBe(true);
+  // The shared Button's focus ring survives the className merge, so the
+  // revealed button also shows where focus is.
+  expect(cls.contains('focus-visible:ring-2')).toBe(true);
+
+  // `group-*` variants resolve against the nearest `.group` ancestor; it must
+  // be this field's own wrapper, so focus in one field reveals only its button.
+  const group = copy.closest('.group');
+  expect(group).not.toBeNull();
+  expect(copyButtons(group as HTMLElement)).toEqual([copy]);
+}
+
+describe('DetailSection read-mode copy button — keyboard focus reveal (#26329)', () => {
+  beforeAll(() => {
+    // useIsMobile() keys off window.innerWidth; the desktop row carries the button.
+    Object.defineProperty(window, 'innerWidth', { configurable: true, value: 1280 });
+  });
+
+  afterEach(() => {
+    cleanup();
+  });
+
+  const objectSchema = {
+    fields: {
+      title: { type: 'text' },
+      city: { type: 'text' },
+      notes: { type: 'text' },
+    },
+  };
+  const section: DetailViewSection = {
+    fields: [
+      { name: 'title', label: 'Title' },
+      { name: 'city', label: 'City' },
+      { name: 'notes', label: 'Notes' },
+    ],
+  } as DetailViewSection;
+  const data = { title: 'Hello', city: 'Paris', notes: '' };
+
+  it('draws one focus-revealed copy button per copyable field, none on an empty one', () => {
+    const { container } = render(
+      <DetailSection section={section} data={data} objectSchema={objectSchema} />,
+    );
+    const buttons = copyButtons(container);
+    expect(buttons).toHaveLength(2); // title + city; the empty `notes` offers no copy
+    buttons.forEach(expectFocusRevealContract);
+  });
+
+  it('focus on the field row sits inside the same group as its copy button', () => {
+    const { container } = render(
+      <DetailSection section={section} data={data} objectSchema={objectSchema} />,
+    );
+    const [titleCopy] = copyButtons(container);
+    const group = titleCopy.closest('.group') as HTMLElement;
+    // The click-to-copy row is itself a Tab stop; focusing it is what
+    // `group-focus-within` turns into the button's reveal.
+    const row = group.querySelector('[role="button"]') as HTMLElement;
+    expect(row).not.toBeNull();
+    expect(row.getAttribute('tabindex')).toBe('0');
+    row.focus();
+    expect(row).toHaveFocus();
+    expect(group.contains(document.activeElement)).toBe(true);
+  });
+
+  it('activating the focused copy button copies its own field', async () => {
+    const writeText = vi.fn().mockResolvedValue(undefined);
+    Object.defineProperty(navigator, 'clipboard', {
+      configurable: true,
+      value: { writeText },
+    });
+    const { container } = render(
+      <DetailSection section={section} data={data} objectSchema={objectSchema} />,
+    );
+    const [, cityCopy] = copyButtons(container);
+    cityCopy.focus();
+    // Enter / Space on a native <button> dispatch `click`.
+    fireEvent.click(cityCopy);
+    expect(writeText).toHaveBeenCalledTimes(1);
+    expect(writeText).toHaveBeenCalledWith('Paris');
+  });
+
+  it('draws no copy button on an editable field (the pencil takes its place)', () => {
+    const { container } = render(
+      <DetailSection
+        section={section}
+        data={data}
+        objectSchema={objectSchema}
+        onEnterInlineEdit={vi.fn()}
+      />,
+    );
+    expect(copyButtons(container)).toHaveLength(0);
+  });
+});