Is anyone actually using agentic payment protocols (x402) in production?

x402 allows AI agents to autonomously pay for services, while ERC 8004 gives agents a form of an on chain reputation. This feels like it could be a major innovation for Web3, but most of these protocols rely heavily on crypto infrastructure, which makes me question their security.

How should we design payment currencies and wallets for agents?

Pertransaction spending limits?

Dedicated wallets or user controlled wallets?

How can we audit critical fees to ensure transaction security?

From what I’ve seen with projects like Stripe's payment infrastructure and Anvita flow's A2A ecosystem, we’re still far from finding a solution that is truly secure, reliable, and auditable.

What do you think is the biggest bottleneck preventing autonomous AI payments from going mainstream?