This repository is the remark markdown ecosystem monorepo. It ships four npm packages: remark-parse (markdown to mdast AST), remark-stringify (mdast AST to markdown), remark (a preconfigured unified processor with both), and remark-cli (a terminal interface). In practice, these packages are thin adapter plugins for unified: they attach parser/compiler functions to a unified processor, merge user settings from processor data, and expose extension hooks that other plugins use to add syntax support. The heavy CommonMark parsing and serialization is delegated to mdast-util-from-markdown and mdast-util-to-markdown, so the code here is intentionally small and focused on clean integration rather than reimplementation. The architecture is a workspace-based monorepo of ESM-only packages. Entry points are `remark()`, `unified().use(remarkParse)`, `unified().use(remarkStringify)`, and the `remark` CLI binary. The primary data flow is: markdown text -> unified parse -> mdast tree -> plugin transformations -> unified compile -> markdown text. Extension mechanisms use processor data fields (`micromarkExtensions`, `fromMarkdownExtensions`, `toMarkdownExtensions`), which keeps core packages stable while allowing the plugin ecosystem to grow without coupling. Maintenance is active: CI runs against multiple Node versions, tests downstream packages as canaries, and the codebase enforces strict TypeScript coverage. Technical drift is low: the packages target maintained Node versions, use current unified/micromark-based dependencies, and follow modern ESM conventions. The design is a strong example of building a stable, plugin-driven toolchain around an AST-processing core.