I have individually addressable LEDs, so I created a domain specific language (DSL) to control the LEDs, meaning controlling the pattern of the LEDs is best done by sending a message to it.
Honestly the DSL really isn't that great. I've been meaning to redesign it using something like ANTLR rather than the mess that I made a few years ago.
I do eventually want to have a local-first way to send messages to the program, but creating that isn't worth my time at the moment.