Delivered when an assistant message fails.
Body POSTed to a registered webhook endpoint when an assistant message reaches a terminal state. Mirrors the AssistantMessage GET response.
Lifecycle events for assistant messages started via the developer API.
Opaque assistant message id (e.g. vg_mesg_...).
Seconds since epoch (Unix timestamp) when the message reached a terminal state.
A single message in an assistant chat. Discriminated by role.
Acknowledge receipt