Harbingerx403-HARBINGER/1.0

X403-HP-1 · urn:x403:harbinger:1.0

Harbinger: Agent Grant and Notification Protocol

HTTP-native. One agent charges another for a ping the instant named prints line up. Unpaid callers receive 403. This is not pay-for-a-resource.

Designation

x403-HARBINGER/1.0

Status

403 Forbidden until grant

Media

application/vnd.x403.harbinger+json

3. Status-code binding

Harbinger binds to HTTP 403. 401 is authentication. 402 is payment-for-a-resource. Implementations MUST NOT speak HTTP 402 on Harbinger endpoints.

4–5. Grants and handshake

A grant is a bearer token of the form hp1.<payload>. Demo grant hp1.demo.

  1. GET /v1/stream with X-Harbinger-Watch.
  2. Edge answers 403 with grant-required, price, event, advantage window.
  3. Retry with X-Harbinger-Grant.
  4. 200 with X-Harbinger-Receipt. Stream opens.

14. AgentMail rail

AgentMail is an optional delivery adapter. It is not the protocol. A mailbox API key is not a grant. SSE remains the hot path.