A2A lab
Halden's support agent asks the Payments agent to refund a duplicate charge. It reads the Payments agent's Agent Card, sends a message, and follows the task until it ends; when the Payments agent needs a confirmation, the support lead answers inside the same task. Both sides are the official A2A JavaScript SDK (protocol 1.0) running in this page, each agent's decisions come from a LangChain model, and the payments themselves are simulated. Turn on Intercept to hold messages on the wire and tamper with them.