One document, three responsibilities
The native Mac project reads a local Markdown file, turns its structure into a rendered page, and keeps navigation linked to the source folder. Its reader uses a WebKit view, but the rendering resources for syntax highlighting, Mermaid and KaTeX are bundled with the app. That architectural choice lets those features work without fetching a public CDN during reading.
The app also supplies an asset handler for local images and a separate Finder Quick Look extension. These are different surfaces with different access boundaries; a successful preview of one file does not prove an entire folder is available to every extension. The file watcher observes the open document, not an entire project directory for newly created files.
Export is another step
The source includes commands for rendered PDF and HTML export. A save panel chooses the destination, and the page is captured or written from the rendered view. That tells us the command exists; it does not prove every asset remains portable in every exported file. The PDF checklist and HTML handoff guide therefore ask readers to inspect the actual output.
Do not confuse the web demo with the app
The free online reader parses a single local file in a browser tab. It deliberately refuses document images and active HTML, does not open local document links, and leaves Mermaid and math source visible. This reduces web-tool scope and avoids silently sending document resources elsewhere.
These observations come from the current project source, not a tested public release build. Aero Markdown’s Mac app and checkout are not publicly available yet. The rendering corpus provides files for future release testing.