#Editor

A document — a file, a note, a diff, a commit, a pull request — opens as a pane, in the same split grid as the terminals. Fold's editor is a good editor, not an IDE: no language intelligence, ever.

#Document panes

• Open a file from the Files pane, from search (⌘P), or from a diff. The first one splits the focused terminal and takes 54% of it. Every later document opens into that same pane — one document pane by default, however many documents you have open.
• Open to the side makes a second one: ⌘-click any row that opens a document, or use Open to the Side in the explorer's file menu or a note card's menu.
• The dock's file group is the one listing of everything open — a tile per document, no tabs. A tile has three states: active (showing in the pane you used last), onstage (showing in another visible pane) and idle (open, not showing).
• A pane holding more than one document says so. Past one document its header wears a count beside the ✕. Click the count and the pane lists what it holds — what it shows, then what it has shown that is still open, each with its own ✕.
• A tile's click tucks its pane and brings it back — there is no minimize. ⌘E tucks every document pane and restores the set.
• ⌘⇧↩ zooms the focused pane to the whole stage; the same key puts the grid back.
• Drag a pane by its header to move it anywhere in the grid; drag any gutter to resize.
• ⌘⇧W closes the document in front — it asks first while the file has unsaved edits. ⌘S saves.

#What the editor does

• Syntax colour for the usual languages, through tree-sitter.
• A change gutter: what differs from git HEAD, live as you type.
• Files follow the disk. When an agent rewrites a file you have open, it reloads under you.
• Markdown preview — ⌘⇧M switches a markdown file between source and preview.
• Diffs with clickable line numbers that open the file at that line.

#Diffs, commits and pull requests

A change's diff, a commit and a pull request are each their own document, with their own tile. Several stand at once — the dock's file group grows to hold them, and scrolls past six. Opened to the side, they stand side by side. A markdown file inside a diff can be read as rendered writing in place: one toggle on that file's own row, and the code beside it never moves.

A followed diff whose changes are all staged away keeps its pane, showing its "nothing left" state, rather than collapsing the grid under you.

#Keys inside the editor

Key	Does
⌘C / ⌘X / ⌘V	copy, cut, paste
⌘A	select all
⌘Z / ⌘⇧Z	undo, redo — per file
⌘← / ⌘→	line start, line end — ⇧ extends the selection on every move
⌘↑ / ⌘↓	file start, file end
⌘⌫	delete to line start