底本 teihon [tay-hone] · the base text of an edition
Two panes over one document. Type in either and the other keeps up, and when the agent working alongside you rewrites the file, every line it touched is marked in both panes.
Mac and Windows
Change review
When a file changes on disk, the new text arrives in the open window and every altered line is marked in both panes, at the same time. Step through the changes one by one, reveal what a line used to say, and clear the marks when you have read them.
No diff view to open, no second window. The document you are reading is the document that changed.
Terminal
Several shells at once, as named tabs, opening in the folder you have open rather than wherever you happened to be. One for the agent, one for the dev server, one for git.
Real shells, with your own profile and your own aliases, not a command runner pretending to be one.
Markdown source on the left, a fully editable rendered view on the right. Edit either. The caret is mirrored in the pane you are not typing in, so you never lose your place.
Scroll either pane and the other follows to the same passage, matched by where you are in the text rather than by how far down the bar has travelled.
Open a folder and see every document in it, each marked with what git would say about it: modified, added, untracked. You can tell at a glance what is not committed yet.
A fenced mermaid block draws itself. Sequence diagrams,
flowcharts, state machines, all written in the document, so an agent
can revise the picture along with the paragraph that explains it.
Add one from the toolbar, or drag it straight onto the window. A picture from your machine is written as a path relative to the document, so the folder still works after it is moved.
Every heading in the open document is listed under the folder in the sidebar, so a spec that has grown long still shows its shape. Click one to jump, and both panes go there together.
Search across every document in the folder, follow links between them, and see which specs point at the one you are reading.
Autosave is on. There are no unsaved-changes dots and no dialog when you close a window, because there is nothing left to write.
No account, no telemetry, no cloud. Your documents are files in a folder, and they stay that way.
Updates arrive quietly and install when you say so.
Open a folder of specs and point an agent at it.