Amp recently achieved it. Apparently it's permitted as long as you use the Claude Agent SDK. https://ampcode.com/news/use-your-claude-plan
You can’t just use your Claude sub on a third party harness without getting blocked even if you use the Agent SDK. Apparently, Anthropic gives “credits” depending on your sub and you can use those _credits_ when you use third party harnesses or Claude -p mode. That usage is not the same Claude sub one would assume it is… It is all quite deceiving. Don’t get a Claude sub unless you’re okay with being locked into Claude Code…