This demonstrates the problem:

ie. we do a submit, click a link, then try to go back.

expected: contents of Users index (url being /Users)

got: same contents for /ShowUser and /Users

Code is at https://github.com/unhammer/ihp-back-button-repro – I just did ihp-new, created a users table with a name column, a users controller and ran it. Nothing out of the ordinary there.
That repo is using newest ihp master, but the problem was there at least as far back as 1.0.1 and I think earlier versions too.
Happens in both firefox and chrome.

A workaround is to use formForWithoutJavascript, but that loses the "interactive" feel (downgrades to web 1.0 🖳). I'd love to be able to have both the js form submission and a working back button.

Possibly related:

• Series of things that leads to a GET/POST error - ideas for fixing it #1893
• redirectTo / redirectToPath / redirectToUrl mutes JS in destination page #451