Great question. Here's one way to do it:
The first is how clunky the process of going from X to flashcard feels to the end user. One way to deal with the fact that we are crossing software border is to add an extra step where highlighting something allows you to go into an "inbox" before any cards are made. It is clear what the user has to do. They read something interesting, and add it to the inbox. When they are ready, they can head over and only then use some sort of automation (either via custom prompt for an AI or otherwise) to make the cards. This gives them another step, or interface, at which they can decide whether or not the thing they highlighted (since highlighting is easy) is actually worth something. It segments the process into clear easy sections: highlighting, deciding which highlights to flashcardify (and therefore keep), and flashcard review.
It definitely is an open-ended process, and I appreciate that apps need to have a strong opinion on how to direct users from start to finish; but I feel this is definitely possible now with cheap and quick AI.
I didn't answer every question but hopefully that helps somewhat.
I like the idea of an inbox where you just toss things you think are worth remembering and maybe having a browser plugin or OS shortcut to save highlighted bits of info, but not necessarily creating a flashcard immediately from it. There's definitely some concrete things I can prototype here to try to make that workflow easier. And I can see how taking those tidbits of info and passing them to AI to create flashcards is doable too.
I'm glad this has resonated, good luck with the prototypes. Let me know if you ever want more feedback.
The hardest part of any system is making it a habit.
EDIT: This comment further down mentions asbplayer. https://news.ycombinator.com/item?id=44023159
The easiest thing, which I believe I suggested, was highlight->action to create a new card front, and highlight->action to creat the back or a new front. It needs to work well casually in general, and easy when focused.
I’m sure AI could theoretically help but not sure it’s necessary. Part of the benefits of most cards is creating them yourself.
Like I said in the other comment, I'm going to play around with some ideas regarding an inbox. I think that on its own would help a ton for just recording things to be converted to flashcards later. There's probably a good in-app UI that can be made to go through the inbox and easily convert the notes created into the front and back sides as well.
From a user standpoint, would it be an interactive process where you highlight things and then click a button to say "turn this into a flashcard", or would it be an automated tool that would scan the content and come up with a list of questions and answers t hat would test the material for you? What criteria would be used to determine what's worth turning into a question and answer? And how granular should the question be? I've seen demos of things that pick out specific facts, like dates or names, from the text to turn into questions, but that might not be that useful to quiz for some material. It seems like a very open-ended process to me, so it would be hard to get right for everyone's needs.