@opral/zettel-markdown

Canonical Markdown conversion for the Zettel 1 document model.

import { fromMarkdown, toMarkdown } from "@opral/zettel-markdown";

const document = fromMarkdown("# Hello\n\n- [x] done\n");
const markdown = toMarkdown(document);

The converter uses remark-parse and remark-gfm for CommonMark plus the formal GitHub Flavored Markdown extensions, and remark-stringify with remark-gfm for canonical output. The supported input and output corpus is the cmark-gfm 0.29 specification fixture pinned in fixtures/gfm; the package tests exercise all 672 upstream examples and independently compare representative output with micromark's GFM HTML implementation.

The Zettel AST has no footnote or other extension node in its core model. Footnote-looking syntax is disabled so formal GFM inputs such as [^a]\n\n[^a]: /url remain an ordinary reference link. Other remark syntax that produces an unsupported node is rejected with MarkdownConversionError so content is never silently discarded. Likewise, export rejects unregistered extension blocks and inline nodes, missing link definitions, invalid tables, and marks that Markdown cannot represent.

Markdown conversion creates fresh _key values. Link definitions are local to each text block or table cell, and raw HTML is retained as inert source in zettel_html or zettel_html_inline nodes.