kubbiai

A2A payload side-channel

A2A (Agent2Agent Protocol) handles agent-to-agent message routing: typing, addressing, ordering. Useful for control flow. Not designed to carry large or sensitive payloads inline.

Pair A2A with kubbi: the A2A message carries metadata and a claim URL; kubbi carries the bytes. The pattern works across organizational boundaries because neither side has to share storage credentials.

How it works

  1. Producer creates a kubbi with the payload. Receives a claim URL.
  2. The A2A message references the claim URL (as a payload reference or task input).
  3. Consumer agent receives the A2A message, follows the claim URL, retrieves the payload.

The A2A bus stays clean: small messages, no sensitive bodies, no size constraints from the payload itself.

Example A2A message

The A2A message body carries the claim URL as a reference. The consumer agent dereferences it to fetch the actual payload.

A2A message with claim URL reference· json
{
  "task": "summarize-findings",
  "from": "research-agent-vendor-a",
  "to": "summariser-vendor-b",
  "payload": {
    "type": "kubbi_claim_url",
    "url": "https://api.kubbi.ai/r/abc123xyz"
  }
}

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