What problem does it solve? APIs and web pages often need to share one URL, but browsers want HTML while API clients want JSON or XML. This Skill implements HTTP content negotiation in a Rango router so a single URL pattern dispatches to the correct handler based on the request's Accept header, with automatic Vary: Accept headers for correct CDN caching. ## Core Features & Use Cases - Negotiated Route Registration: Declare an RSC page plus JSON, text, XML, HTML, or Markdown variants on the same URL pattern; the trie merges them at build time. - Standards-Based Negotiation: Q-value priority, client-order tiebreakers, wildcard fallbacks, and explicit text/x-component opt-in for the RSC flight wire format. - Type-Safe Responses: Use RouteResponse or Rango.PathResponse types to get typed response payloads per negotiated variant. - Use Case: Expose /products/:id as an HTML page for browsers and a JSON endpoint for API consumers without maintaining separate route trees or manual Accept parsing. ## Quick Start Ask the AI to add a JSON variant to an existing Rango route so the same URL serves HTML to browsers and JSON to API clients based on the Accept header.