I use and love openspec and I'm against this session attribution by default setting.

But I do see the value in seeing the conversation that lead to the spec. I make sure that all product decisions go through me prior to the agent writing the spec and the questions I ask and decisions I make could definitely help understand retroactively why something is the way it is.

I guess with the default openspec schema you wouldn't have that but you could customize it or create your own in which the reasoning is encoded fully.