This is all good, but I'm not a fan of my browser being remotely controlled by anyone to modify any of its expected behavior to do special/specific things on different websites without my informed consent.
Even the browser vendor has to be held to the same high standard (or even higher) of being completely open and transparent about what they and when they do it.
Your requirements are already not being met. All the major browsers self-update, employ lists of sites for special handling, and fail to ask you when those are updated.
Of course, you can disable auto-update, and then you're likely to be remote-controlled by someone you didn't choose.
Even the browser vendor has to be held to the same high standard (or even higher) of being completely open and transparent about what they and when they do it.