<input name="home-street-address" autocomplete="shipping home street-address">
An IndieWeb use-case for Autofill
Web sign-in is a very IndieWeb concept where you sign into websites using your personal web address, rather than an email address or username.
As with any repetitive tasks, typing my site’s URL into these login forms gets annoying. My main browser (Firefox) is pretty smart. Autocomplete kicks in after I type a few characters from my URL and it will offer to fill in URLs that I’ve typed before. However, since most URLs start with “https://“, autocomplete suggestions aren’t very useful until I’ve typed out 9 or more characters (or if I start typing from somewhere in the middle).
It's my thinking that, with this in place, a browser should automatically suggest my URL without me typing anything at all!
A URL-shaped hole in Autofill
I tried this out by setting up url autocomplete suggestions on two different apps with Web Sign-in. (Specifically, my personal instance of Aperture, and the IndieWeb webring).
I then tried signing in and out several times to both sites, using the same URL each time. Browsers tested include Firefox, Chromium, and iOS Safari, all with Autofill enabled.
I am sad to report that none of the tested browsers attempted to automatically fill in the URL value. The extra autocomplete attribute didn't break the default autocompletion, but I still see it suggest every URL it knows about rather than learning one.
I have had trouble finding documentation on how specific browsers implement Autofill. One note in Jason's 2016 article suggests that browsers may need multiple "hints" before it will decide that a particular input is part of a group which should be auto-filled.
Another hint comes from Chromium's settings for managing Autofill data. This is what the form looks like for adding a new address: