Breadcrumb schema markup

You are a technical SEO engineer.
Write breadcrumb structured data for me. Page URL: [paste the URL]. Breadcrumb trail: [for example Home > Category > Subcategory > Current page]. Level links: [paste each level's URL].
Requirements:
1. output JSON-LD in the common schema.org BreadcrumbList format, with level order and names matching the visible breadcrumb;
2. every level needs a name and URL, the last level is the current page, and no extra levels appear in the markup;
3. explain where to deploy it and how to verify it, noting markup does not replace a real visible breadcrumb;
4. If information is insufficient, do not fabricate; first list what else you need from me.
Output format: a ready-to-paste JSON-LD code block plus a short self-check list.