[wangkeyu-u]

Fix false-positive clipboard checks without changing the gallery implementation or dataset. The old single-card smoke test passed after both clipboard methods failed and the browser fell back to manual copying; the multi-card test accepted any three-line text.

• Compare the selected names/links and the full single-card prompt exactly against preview-data.json.
• Verify Clipboard API success, API rejection and absence followed by successful legacy copying, and both methods failing with a manual prompt rather than a false success state.
• Check temporary copy-field cleanup and browser errors; document that clipboard interfaces are mocked and these checks do not prove operating-system permissions or visual reproduction quality.

Independent validation: deterministic build with unchanged preview-gallery.html, functional checks over 230 cards, and all four copy branches passed. Two browser-memory mutations now exit nonzero: a no-op copyPrompt and incorrect three-line selected-card output. The auditor reproduced both original false-positive cases before the test changes.

GitHub Actions passed on Linux/Node.js 22 for head 6a00d1a, covering locked dependency installation, browser setup, deterministic build, functional checks and all four copy branches.