[weinzierl]

I'm also an engineer that had to study basic law and what you described matches what I learnt. A contract requires a statement of intent[1], where the bar for this is pretty low, e.g. a handshake. So, many things are considered a contract that a layman wouldn't think of. Of course not literally everything is a contract and the question regarding the GPL here is if this minimum threshold can be considered crossed.

[1] I think this is pretty universal across legal systems, but I could be wrong.