Europe 2026
Building safe Payment Infrastructure for the autonomous economy — Steve Kaliski, Stripe
Overview
This talk addresses the critical need for secure payment infrastructure in an increasingly autonomous economy, where AI agents will act as economic actors. It highlights the inherent risks of agents transacting online, such as purchasing from incorrect vendors, selecting the wrong items, or spending unintended amounts. The core thesis is that while discovery and exploration benefit from non-determinism, financial transactions require strict determinism to ensure safety and prevent fraud.
Who should watch
- AI Engineers building agentic systems
- Product Managers defining agent capabilities
- Builders integrating payments into autonomous workflows
- Anyone concerned with the security and reliability of automated financial transactions
Key takeaways
- Agents are already economic actors, often spending money indirectly through API calls or tokens.
- Key risks in agent payments include buying from the wrong place, the wrong thing, the wrong amount, or using the wrong credential.
- Stripe's approach separates discovery (non-deterministic) from payments and checkout (deterministic).
- Shared payment tokens allow agents to provision payment credentials with specific limits (amount, time, seller) that are enforced by Stripe.
- The Machine Payments Protocol (MPP) uses HTTP 402 status codes to signal payment needs for tool calls, associating payment with specific resources.
- The Agent-to-Commerce Protocol (ACP) provides structured APIs for expressing product catalogs and managing checkout states, enabling programmatic commerce flows.
- API-driven commerce flows, supported by protocols like ACP, are essential for maximizing deterministic interactions between agents and businesses.
- *Discovery should remain non-deterministic; payments and checkout require strict determinism.*
Notable quotes
Steve Kaliski: *Discovery and exploration benefit from non-determinism. But credentials, payments, and checkout require determinism.*
Steve Kaliski: *Agents are already economic actors. They have their own currency and tokens.*
Steve Kaliski: *Discovery we should keep with non-determinism that's perfect. Payments and checkout and credentials we want to shift towards exclusively deterministic.*
Unofficial community note. Prefer the recording for nuance.