I have encountered the opposite of this. All of the latest pro tier models are still fighting for their lives to use powershell correctly, really basic things like quotes, escaping, heredocs. Doesn't matter what I put in agents.md or instruct it to do. You just have to accept the token tax of it stomping on rakes until it figures it out itself and then keep using that session.

It's bad enough that I've considered writing some sort of cursed bash->posh translation layer

Yet it has no issues at all implementing and then writing slopjective-c 3.0