> 2) If there's a form input at each step, the server needs to store that info and be aware that the user has an incomplete checkout. Now the user is at step=2 and presses the back button, or clicks on the step=1 link. In that case, the server should know the information stored in the point no. 2 above, and return an HTML form with the data pre-filled based on the last state.

The problem is that when you press back button in the browser, it doesn't make another request to the server. It reloads the page from browser memory. A link back can be made to work, but that's not what I was speaking to.

I tested the most trivial case, when you return a response, and push navigate to next step, then press browser back button, form state is not retained. Both chrome and firefox do not restore the form state on navigation back after a url push navigation.

I don't think that without some client side JS that saves/reloads prior form state this is a solvable problem because of browser behavior. Either that, or perhaps use different divs for each step then have js hide/show them which is what I will try next but involves writing js to do so.

EDIT: tried multiple divs on same page, same behavior so that will not work.

It's pretty clear that htmx hasn't considered back button much at all, it also clobbers the page titles in history as well (https://github.com/bigskysoftware/htmx/issues/746), but that's a fixable problem.