('because they said so, isn't a good answer)
If you don't like those terms you can use the API.
Using Claude Code's auth flow with OpenCode is no different than using a custom client to abuse Gmail/Google Photos free tier as blob storage.
You get a loss leading product under certain good faith terms, if you break those terms you're abusing the product.
What is the upside to Anthropic if we use ClaudeCode but not OpenCode? If it is such a loss leader, why would they even offer it? By using it, even within their terms, you are still abusing their good will. No?
(You also said the alternative to not liking the terms is to use their API. There is another alternative, which is to keep using it against their ToS and risk a ban. Or use a different provider. So the situation is more nuanced than "this" or "that")
Yes. That is all that matters. That is the contract you've signed with the business, end of story.
They have their reasons (3P clients suck at caching, this is a subsidized tier to create subscription lock in, etc) but that's besides the point. If you sign a contract, you abide by its restrictions or you categorically abusing the offering.
> There is another alternative, which is to keep using it against their ToS and risk a ban.
No one working on a project of value and no sane business would do this. The people doing this are not serious/mature people. Frankly any dev that intentionally does this at a real company would be fired.