Not sure if this can work. We played around with something similar too for computer use, but comparing embeddings to cache validate the starting position is super gray, no clear threshold. For example, the datetime on the bottom right changes. Or if it's an app with a database etc, it can change the embeddings arbitrarily. Also, you must do this in every step, because as you said, things might break at any point. I just don't see how you can reliably validate. If anything, if models are cheap, you could use another cheaper llm call to compare screenshots, or adjust the playwright/api script on the fly. We ended up writing up a quite different approach that worked surprisingly well.

There are definitely a lot of potential solutions, I'm curious where this goes. IMO an embeddings approach won't be enough. I'm more than happy to discuss what we did internally to achieve a decent rate though, the space is super promising for sure.