A great thing about working in California is that state law makes employment contract clauses that say the company "owns your brain" unenforceable. Among other

A great thing about working in California is that state law makes employment contract clauses that say the company "owns your brain" unenforceable. Among other things that puts a real damper on lock-in with non-compete clauses. Employment contracts typically have a "list of inventions" attachment, on which you can list everything you lay claim to having invented (whether you actually worked on an artifact or just designed something). I was at times extremely liberal in what I listed as inventions, and no employer ever balked. FWIW, that includes two FAANGs. All that said, if you intend to moonlight on a project that significantly overlaps with your employer's business, you're on shaky ground ethically and legally. For such projects it becomes difficult to claim you did all the work on your own time, with your own resources.