Coinbase, Stripe, Google, and Visa have launched competing AI-powered payment infrastructures, processing 176 million transactions worth $730 million. These developments mark a significant shift in payment systems, with traditional giants investing $8 billion in acquisitions to secure their positions. The new architectures include Coinbase's x402, Stripe's MPP, Google's AP2, and Visa's AI-ready tokenized credentials, forming a comprehensive payment stack. Stablecoins, particularly USDC, dominate the settlement layer, handling 98.6% of transactions. This reliance underscores both the strength and vulnerability of the ecosystem, as it hinges on a single stablecoin issuer. The payment stack's vertical integration is evident, with Coinbase and Stripe covering multiple layers, while traditional firms like Capital One and Mastercard make strategic acquisitions. The machine economy is evolving, with AI agents accounting for a significant portion of transactions. However, regulatory challenges loom, as upcoming laws like MiCA and the EU AI Act do not address autonomous machine transactions. The future of this ecosystem depends on developing a robust trust infrastructure to ensure secure and reliable agent commerce.