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Markdown

Markdown is a first-class citizen: the same file gets tree-sitter highlighting in the editor — including fenced code blocks colored in their own language — and a live preview beside it.

The preview

Opening a Markdown document opens the preview pane automatically, to the right of the source. View → Toggle Markdown Preview (⌥⌘P) hides and shows it.

  • The preview updates as you type, patched in place — no reload, no flicker, no lost scroll position.
  • Scrolling either pane follows in the other.
  • A link goes to your browser when clicked; the pane stays on the document. A link into the document itself scrolls the preview to it.
  • Rendering supports CommonMark plus tables, strikethrough, task lists, and footnotes, and its styles follow the system (or configured) appearance.

Rendering happens in the core (the shell only owns the pane), so the exact same HTML will later feed other outputs.

Hugo

Blog posts written for Hugo are Markdown with two additions, and Textchum reads both without Hugo being installed.

Front matter — TOML between +++, YAML between --- — is highlighted as the language it actually is, kept out of the prose the spell checker reads (a slug is not a misspelling), and rendered in the preview as a small metadata block rather than a paragraph of fences.

Shortcodes — {{< figure src="…" >}} and {{% notice %}}…{{% /notice %}} — are highlighted as the calls they are, skipped by the spell checker, and shown in the preview as a labelled placeholder. They are never executed: running one needs Hugo's template engine and your site's own layouts, so a placeholder is the honest thing to show. The body of a paired {{% … %}} keeps rendering as Markdown, which is what Hugo does with it too.

The outline (⇧⌘O) lists a post's headings even with no language server running, nested by depth — a long article navigates like a source file. Headings inside fenced code and front matter are not mistaken for structure.

Finally, files under a layouts/ directory are treated as Go templates rather than plain HTML: the markup highlights as HTML and the {{ … }} actions stand out from it.

JSON front matter (the brace form) is not recognized yet; TOML and YAML cover what Hugo writes by default.

Not there yet

  • Precise scroll sync via source anchors (today's sync is proportional, which drifts on documents with very uneven block heights).
  • Syntax colors inside preview code blocks (the editor colors them; the preview shows them plain).
  • The hybrid/WYSIWYG editing mode — the preview pane is deliberately the first of the three Markdown tiers.