Can I deposit straight into an AI agent, or only to my balance?

You can do either. A plain deposit simply tops up your euro balance, which you can then use for trading or to start an AI-agent investment whenever you like. Alternatively, when you make a crypto deposit you can attach an AI agent and an investment plan to it — in that case the deposit must meet that plan's minimum, and it's treated as funding for that specific investment. If you just want flexibility, deposit to your balance first and start an investment separately from the Invest page. Either way the money is only credited after your deposit is approved.