feat: event_feed capability and agent_hints on fulfillment events

[hemanth]

Right now agents have no standard way to know what commerce events a business emits or how to receive them, leaving integrations wired up outside the protocol. Pairing discoverable feeds with per-event hints closes that gap and makes UCP events first-class for agentic workflows, without touching any required fields or existing transports.

event_feed on the business profile lets a business advertise a typed event stream (order updates, price changes, low stock). Agents read the profile, pick a transport (webhook / sse / poll), and subscribe.

agent_hints on fulfillment_event lets a business attach advisory action suggestions to shipment events (e.g. notify_user on delay, escalate on undeliverable). Non-normative — the agent decides whether to act.

Example

{
  "event_feed": {
    "url": "https://store.example.com/ucp/events",
    "event_types": ["dev.ucp.order.shipped", "dev.ucp.order.status_changed"],
    "transports": ["sse", "poll"]
  }
}

{
  "type": "failed_attempt",
  "agent_hints": [
    { "action": "notify_user", "priority": "high" },
    { "action": "escalate", "condition": "attempts > 2" }
  ]
}

Category

• Core Protocol
• Capability
• Documentation