Show HN: React Prompt Kit (github.com)

React Prompt Kit is a new TypeScript library that turns JSX/React into structured prompts (XML + Markdown) for LLMs, inspired by Claude’s XML-tag best practices. It provides 50+ composable components (Context, Task, Instructions, Examples, Code, etc.) so you can author prompts declaratively alongside your UI code, then reliably render them into clean <tag> XML blocks or Markdown. The package includes a prompt() function, full type definitions, and a runnable demo so teams can iterate prompts as code and ship consistent, readable prompt artifacts to any model that accepts structured inputs. Technically, the kit maps standard HTML elements inside components to Markdown (h1→#, p→paragraphs, ul/ol→lists) while wrapping higher-level pieces in XML tags (<context>, <instructions>, <examples>, …). It distinguishes block-level vs inline behavior: blocks preserve structure and newlines; inline elements strip XML tags and normalize whitespace to prevent XML injection (with <code> preserving tags as literal text). Code blocks are escaped intelligently by choosing longer backtick fences when needed. These features make prompts more maintainable, type-safe, and secure—helpful for reproducible prompt engineering, automated testing, and teams that need consistent structured inputs for LLM pipelines.