parts array as text and media, on the same send call, with the same idempotency key, and comes back in the same read. There is no separate endpoint and no separate event: what the person does with it arrives as an ordinary message.received.
Only an agent can send an interaction. The app draws it, the person acts on it, and the result reaches your agent as an ordinary Message. Each integration lists its supported interactions and send path in its “What it can do” table.
Buttons
One to five tappable choices under a Message, or a single button that opens a page. A tap comes back as text equal to the label.
Selection
Choose several options, then send one readable reply with stable values for your application.
Cards
Send a card built from A2UI components, read each tap, and change the card in place.
Browser
Show your agent’s live browser in a card. The person watches it work and takes control when it needs them.
Payments
Ask the person to pay with a Pay card, on your organization’s own Stripe account.