{
  "dataset": "glossary",
  "record": {
    "id": "markdown-twin",
    "term": "Markdown Twin",
    "category": "protocols",
    "short_def": "A clean markdown version of an HTML page, served from the same URL via content negotiation when a client requests text/markdown.",
    "long_def": "Markdown carries the meaning of a page in roughly a tenth of the tokens of the equivalent HTML. Agent fetchers (Claude Code's WebFetch, Cursor, Cloudflare's edge) request it with an Accept: text/markdown header; humans still get the styled HTML.",
    "see_also": [
      "content-negotiation",
      "llms-txt",
      "token-economics"
    ],
    "etymology_origin": {
      "value": null,
      "verify_status": "verify-against-primary-at-build",
      "source_hint": "https://datatracker.ietf.org/doc/html/rfc7763 — 'markdown twin' is an agentic-web practitioner term with no single coiner/standards body; text/markdown is registered in RFC 7763 (2016)"
    },
    "related_to": [
      "content-negotiation",
      "llms-txt",
      "token-economics",
      "rag"
    ],
    "contrast_with": "Unlike a separate /page.md URL, a markdown twin lives at the SAME URL as the HTML and is selected by the Accept header via content negotiation — one canonical URL, two representations.",
    "example": "Claude Code's WebFetch and Cursor request the markdown representation with an Accept: text/markdown header, receiving roughly a tenth of the tokens of the HTML.",
    "source": "https://datatracker.ietf.org/doc/html/rfc7763",
    "status": "emerging",
    "why_it_matters": "The markdown twin is the canonical way to serve agents a cheap, clean, low-token version of a page without maintaining a duplicate site.",
    "sameAs": [],
    "bridge_entity": "agent-readiness",
    "last_verified": "2026-06-15",
    "md_twin": "/glossary/markdown-twin.md"
  }
}