Which turns actually get a checkpoint

Only turns that were actually allowed to change something create a checkpoint. A turn that only read files and answered a question, with nothing written or edited, does not create one, since there is nothing that checkpoint would need to protect against.

/rewind is aware of this and skips straight past any purely read-only turns to the most recent one that genuinely touched your working tree.

This matters specifically when you pass a number: a run of a few read-only questions sitting in between two real edits does not throw off the counting, /rewind 2 still means the last two turns that actually changed something, not the last two turns of any kind.

This also means asking a question, getting an answer, and continuing to work never eats into your available rewind history the way an actual edit would. Investigating freely between real changes costs nothing in terms of what remains recoverable.

A turn that was declined at the permission prompt, nothing actually written or changed as a result, is treated the same as a purely read-only one for this purpose: no checkpoint, and /rewind skips past it the same way.