The redline moved to where you ask for it

Opening a document used to mean opening a review of it. Every markdown page rendered its recent history as a redline — insertions underlined, deletions struck through, cards down the side — whether you had come to read the document or to review it.

Reading is not reviewing. A document page now shows the document.

Where the redline went

Versions. The redline is now what a version comparison looks like, and a comparison only exists once you have said which two versions it is between.

The version list is the picker — there is no separate dialog to fill in and nothing to remember between clicks:

• Compare with current sits on every version's row. That is the question most people arrive with — what has happened since? — and it costs one click. It is absent on the current version's own row, where it would compare a version with itself.
• From and To claim any two versions as the ends of a comparison. The bar at the top says what will be compared; Compare stays inert, and says why, until both ends are named.
• Claiming an end that would invert the pair releases the other one instead of offering a backwards comparison. The picker cannot be put into a state that Compare would have to refuse.

What a comparison shows

Prose renders as the redline you already know: every change between the two versions marked up inline, with a card naming who made it and when. Show the source diff switches to the side-by-side view when you want to see the raw markdown — front matter, link syntax — and other content types go there directly.

Comparing against the current document stays live: further edits appear as they land, and each change can still be reverted with ↩. Comparing two past versions pins the view to the document as it stood then — there is nothing on screen to revert into, so revert is not offered.

Comments are unaffected: they live on the document's page, which is where the conversation about a document belongs.