You can use the harness sdks instead of the model APIs directly. Eg if you use Claude agent sdk you still can have plan mode, questions, todo lists, sub agents,

You can use the harness sdks instead of the model APIs directly. Eg if you use Claude agent sdk you still can have plan mode, questions, todo lists, sub agents, background tasks, workflows, nearly everything that Claude code has and taking advantage of how it + anthropic models are complementary.