It looks like this will re-render the the preview on every keystroke. That might be a bit expensive. The outline view re-renders on every file save. We do that automatically 1 second after the user stops typing. We may need a bit more architecture around the editors, to make it easier to periodically update something after the content has changed. Can you either:

- add a TODO: so we can track this, or
- look at instead resetting a short timer here, and have the timer cause the preview to re-render