Cool! How do you plan to deal with theft? Most bike lights are trivial to steal. I tend to avoid the fancy ones since in my experience lights disappear immediately as soon as the bike's parked (unless I remove them and put them in a bag every time I park, but that's a pain). Curious how you're addressing that.
That's something I only put a little bit of thought into, as I'm not very worried about my bike getting stolen.
It would be non-functional if someone stole it without stealing the magnet and reed switch as well, but they wouldn't know that.
There's a bit of a trade off, as you're going to want to remove the light to charge it up, in that if you want it to remove easy, it will be easy to steal, and if you want it to be hard to steal, it will be a pain to charge. I don't have any solutions for that yet.
