Even if your company works on a direct competitor to Linux?

This. I have it in my contracts or a rider if they don't like amending the contract itself. I write code, when I stop working for you for the day I still write code. Yes it's lucky that I can get paid to do the main thing I enjoy, but you aren't paying me for the stuff I do off the clock. I will let you know about any major pieces of software I write (not like twenty line Python scripts for managing my music) and if you detect a conflict that's the moment to object, if you do then I'll work on something else, otherwise I own it outright and that's fair.

Good employers don't want to abuse you, and in turn don't want to get abused, drawing a line is something they can understand and their lawyers can get their heads around. "This is mine, this is yours".

Right, but once the devs release something valuable into the wild, well, the cat is out of the bag. The implications can be seriously damaging to the company. It can be as severe as invalidating patents or infinging patents belonging to other companies. Can be evenvia a dependency. I can’t believe devs make those decisions without any supervision.

However, if that is the case, I’d love to know how so one can implement similar processes internally!