The manuscript

Files you can still read in ten years.

The book is a directory. Folders are parts, filename prefixes set reading order, and metadata is YAML frontmatter at the top of each file. Every change is an ordinary git commit. Nothing needs Byline to open it, and nothing about the record depends on us continuing to exist.

Working in it

Views for the whole book Write, outline, corkboard, focus and split. The outline is a table of status, word counts and targets you edit in place. Typewriter scrolling keeps the line you are typing near the middle without fighting you when you scroll by hand.
Structure you can move Drag a chapter or move it with a keystroke; siblings renumber and git records the rename. Notes and cut material live beside the manuscript and stay out of the compiled document.
Links between chapters Reference another chapter by name and it resolves. Each chapter shows what links to it. In the printed document a link becomes its label, because a printed page has nothing to click.
Search that crosses works Regex, scoped by folder, facet or work. Replace with a preview and an automatic snapshot. One search across every project in the repository.
A pinned reference Hold a chapter or a research note open, read-only, while the main pane moves. Read-only on purpose: a second editor invites editing the thing you are consulting.
History per file Every commit with its diff, and restore. The restore is itself snapshotted, so changing your mind again costs nothing.