Does Anthropic not actively ban people using oauth tokens in non-claude-code harnesses?

Yeah, for direct to Claude you need an API key. You can use other subscriptions like GitHub Copilot that expose Claude, but that path has been blocked.

Surely CC has a lower price? How much do you have to pay Cursor for equivalent to what's provided in a 20x Claude Max plan?

200$

https://cursor.com/pricing

If I was paying API costs, I'd be spending about $1700/mo to get what I use on Claude's 20x plan. My understanding was that Cursor would give me about 1/4 of that, on their 20x plan.

I don't know. My company pays for it.