atriumatrium

Markdown editor pane

Rich Markdown editor with RTE and source modes.

The markdown editor pane opens .md files in a rich-text editor built on Lexical and MDXEditor, with a one-click toggle to a raw source view.

Opening

  • Drag a .md file from Finder or the sidebar file tree.
  • atrium path/to/file.md.
  • Click a .md file in the sidebar file tree.
Other Markdown files (.markdown, .mdx) open here too.

Two modes

Toggle the mode with the view-mode button in the pane header.

  • RTE (Rich Text) — WYSIWYG editing. The pane shows a floating toolbar when you select text with:
- Bold / italic / underline / strikethrough. - Inline code and code block insertion. - Heading level picker. - Ordered / unordered list. - Link insertion and editing. - Image insertion. - Table insertion and cell editing. - Blockquote and callout (directive) insertion.
  • Source — the raw Markdown in a Monaco-style editor with syntax highlighting, for people who prefer to type **bold** directly.
The current mode is persisted per pane and applied on reopen.

The pane header

  • Dirty indicator when there are unsaved changes.
  • View-mode toggle between RTE and source.
  • Outline / heading navigator — click a heading to jump, useful on long documents.
  • Book view toggle — wraps the content in a fixed-width centered column with configurable width and margin, for comfortable long-form writing.

Inline comments

Select any text in RTE mode and a floating 💬 button appears beside the selection. Click it to open the comment composer:

  • The composer anchors the comment to the exact text range you selected and shows that text as the anchor preview.
  • The composer respects atrium's UI scale, so its toolbar buttons and font size stay proportional under Cmd+= / Cmd+-.
  • Write the comment and submit with Cmd+Enter (or the Submit button).
  • Comments are saved in the Markdown source itself as MDAST directives, so they travel with the file — commit them to git, share the file, open it elsewhere, and the annotations come along.
A comments sidebar opens on the right of the pane when the document has any comments:
  • Header shows the total count.
  • ▲ / ▼ buttons jump to the previous / next comment; the anchored text highlights as you navigate.
  • Each comment shows the author, timestamp, anchored text snippet, and body.
  • Edit or delete a comment from its card.
  • Click a comment to scroll the editor to its anchor; click the anchor text to reopen the comment.
Because comments are stored as directives, the source view (raw Markdown) shows their textual form. Don't hand-edit that syntax — round-trip through the RTE sidebar to avoid corrupting the anchor ranges.

Keyboard

  • Cmd+S — save.
  • Cmd+F — find in file.
  • Cmd+B / Cmd+I — bold / italic (in RTE mode).
  • Cmd+K — insert link when text is selected.
  • Cmd+V — paste images directly into the editor (see below).
  • Cmd+Enter — submit a comment when the comment composer is focused.

Pasting images

Paste any image on the clipboard with Cmd+V to drop it into the document at the cursor. atrium saves the bytes alongside the open file (typically into an images/ folder next to the doc) and inserts a relative-path image reference, so the image travels with the document in git.

When you copy an image from inside your workspace (for example, via Finder → Copy on a file already tracked in your project), atrium recognises the source and reuses the existing file instead of saving a duplicate. The inserted reference points at the original path.

Customizing the editor

Settings → General → Markdown editor lets you set:
  • Default font family — any installed font, not just monospace.
  • Font size (default 14).
  • Text alignment — left / center / right / justify.
  • Book view — enabled flag, fixed width, side margin.
  • Default view mode — whether new Markdown panes open in RTE or source.
Changes apply to all Markdown panes on the next open. Existing panes keep their current per-pane state until reopened.

Persistent state

  • File path.
  • Dirty flag.
  • Current view mode (RTE vs source).
  • Scroll position and selection.

Constraints

  • Custom HTML inside Markdown is rendered as opaque blocks but not edited inline — HTML comments and inline raw HTML round-trip through both modes intact and are not mangled as stray text directives.
  • No live code execution in the document — code fences render as syntax-highlighted blocks only.
  • Very large Markdown documents (tens of thousands of lines) can slow RTE mode because of Lexical's reactive tree; switch to source mode for those.