AP2 Challenge and Step-Up Flows

Before writing code

Fetch live docs:

1. Fetch https://ap2-protocol.org/specification/ for challenge flow specification
2. Web-search site:github.com google-agentic-commerce AP2 challenge OTP 3DS step-up for implementation examples
3. Fetch https://ap2-protocol.org/topics/privacy-and-security/ for security context
4. Web-search ap2 protocol 3DS2 OTP challenge redirect for integration details

Conceptual Architecture

What Challenges Are

Challenges are additional authentication steps that any participant in the payment ecosystem can require during an AP2 transaction. They provide an extra layer of security beyond the mandate signatures.

When Challenges Occur