Ask HN: In the wake of Amazon suing, what can an employee do and not do?

I don't think you have to worry about side projects, generally, from a programmer's perspective. The guy in question, if I read the right link, was a "strategic partnerships manager", which is another way to say "sales guy". I'm oversimplifying, but the point is that his job was to develop relationships for his employer, on his employers dime and time. The relationships were his work product. In the sales world, those non-competes matter because relationships follow people, generally speaking. When a relationship manager goes to a competitor, he puts his first employer's business at risk. Directly.

This is not at all like programmers working on side projects. The equivalent thing for a programmer would be to run off with the source code you wrote for your employer and take it to another employer, which is an obvious no-no. The grey area for side projects is defined by how much your employer thinks it might be competing (or directly related to) your paid work. Some employers explicitly don't care, while others do. You need to consult your employment agreement first and the state law where you live second. If it's not clear after that, consult a lawyer. FYI: this is a good thing to do before taking a job.

Side projects can be a problem from a patent perspective. Some companies will want rights to anything that you think up during the time of your employ with them, whether it is directly work related or not.

The blue LED was invented by a Japanese engineer (Shuji Nakamura) on his own time, but his company claimed the rights, cue a long court battle. https://en.wikipedia.org/wiki/Shuji_Nakamura