Is it safe to let an AI agent or AI browser log in to my email, bank or shopping accounts?

The specific risk is prompt injection: instructions hidden in a web page, email or document tell the agent to do something you never asked, like forwarding your emails or entering your card details. Brave showed Perplexity's Comet browser could be tricked this way in 2025, and the makers say it is not solved: Anthropic reports 0.3% of strong attacks still getting through against Claude Fable 5 in Chrome with all its safeguards on. So give an agent only the accounts a task needs, keep it off banking unless you watch every step, ask for narrow jobs ('reply to these three emails', not 'handle my inbox'), and read each confirmation before approving. ChatGPT's Lockdown Mode (Settings, Security) turns off browsing, agent mode and connectors when you work with sensitive files.