When I type A and last used was amazon/order it will fill amazon/order, and when I hit backspace even once it goes back to just a not amazon. What I suggested was when typing A it autocompletes only to the main magicword item before a / such as amazon, and then only if you hit tab it should then add the / and autocomplete whatever last used sub magicword under that you have (Hitting A + TAB for example). At that point the functionality would be the same such as hitting s to change from amazon/order to amazon/subscribe. But also if you have amazon/order, hitting tab or backspace should go to just the main magicword amazon without the /. The magicwords for this example I use are amazon to my smile.amazon.com
main order page that donates to charity but otherwise the same as using amazon, amazon/order showing my orders, amazon/profile showing my profile, amazon/review showing items to review, amazon/search to do a general search, amazon/subscribe to see my subscribe and save and could add other categories like amazon/dvd such as to search only dvd category, amazon/music. I also have two amazon credit cards I have to add, one is their store card and the other is the amazon visa. I also have netflix launching my queue of netflix and netflix/search to search it because using dvd alone for several sites for example. Again, if it showed note line when the magicword doesnt use $w$, then I could have amazon/sd for search dvd instead of amazon/searchdvd and wont have to remember them since it will show a single line note what it is, or even just use asd then or amo for amazon order. I do that now with the google search bar but cant remember all the short terms for the dozens I use such as yt to search youtube.
Again it would be good to be able to map the hotkey to bring up the directory like you have for alt-m and if you hit the alt-m with a blank bar it should show all the magicwords. I'd rather use down arrow to bring that up and right/left arrow to cycle the past autocomplete for example. And somepoint being able to add selectable hotkeys to individual magicwords, that is the fastest without even launching the bar if hidden but likely many would just use 5 or so and why you made the program.