Some features:
- Multiple views into an independent repo of plain text notes (with [some line
  drawings](http://akkartik.name/lines.html)).
- Notes can have arbitrary named relationships (links) to each other,
  resulting in a graph.
- The primary visual metaphor is an infinite 2D surface of fixed-width,
  non-overlapping, notes that can be operated on with an extensible set of
  commands.
- Commands usually (but not always) create new columns of notes. Each column
  is an independent visualization of a subset of notes.
- App sources can be seamlessly edited from within the app (though packaging
  up modifications to share with others currently has some seams; see below)
- Notes can contain hyperlinks in [[wikiwords]] to other notes. Hyperlinks
  can't contain spaces. Clicking on a hyperlink opens the target in a new
  column.
- A few other things. Explore the command menu and palette along the top.
Some videos to help visualize these bullets (albeit with outdated UI):
  * https://archive.org/details/akkartik-pensieve-2022-07-27 (4.5 minutes)
  * https://merveilles.town/@akkartik/108766067153506592 (30 seconds)