For the core sim code (the C++) and source instruments (TS/JS/HTML), there are no plans to make those open source at this time.
However, from a tooling perspective, the JS/HTML debugger that we use will be coming soon, so nobody will be at a disadvantage. There are also plans to make the TS typings available, but I don’t have a timeline on that one yet. We worked just fine without them before, but it is always nice to get a little more intelligence into the IDE while developing.
-Matt | Working Title