A2A interop

DARTC is the transport binding. A2A (Agent2Agent) is the semantic layer GemmaPod carries over that transport. Together they let a GemmaPod pod be discoverable and addressable by any A2A-compatible agent or platform.

What ships in v0.1

Agent Card discovery on a2a.discovery. The Host derives an A2AAgentCard from the signed pod manifest (pod name, persona, signed tools as skills, DARTC binding metadata, pod id, owner pubkey) and pushes it once at session start.
Type definitions for A2AAgentCard and A2ADiscoveryPayload in @gemmapod/dartc.

AgentCard shape (as we use it)

interface A2AAgentCard {
  protocolVersion?: string;
  name: string;
  description: string;
  url?: string;
  capabilities?: Record<string, unknown>;
  skills?: Array<{
    id: string;
    name: string;
    description: string;
    tags?: string[];
  }>;
  provider?: {
    organization: string;
    url?: string;
  };
  extensions?: Array<Record<string, unknown>>;
}

interface A2ADiscoveryPayload {
  kind: "AgentCard";
  card: A2AAgentCard;
}

Subscribing in your host

The browser runtime emits a2a.card on the typed bus when one arrives:

runtime.events.on("a2a.card", ({ card }) => {
  console.log("connected to", card.name);
  renderAgentInfo(card);
});

// or read after the fact:
runtime.a2a.card; // A2AAgentCard | undefined

On the wire

A2A objects ride the envelope's a2a field; DARTC delivery metadata (stream / ack / chunking) rides dartc:

{
  "version": "0.2",
  "topic": "a2a.discovery",
  "from": "pod:hello-pod:origin",
  "to": "visitor:session-pubkey",
  "a2a": {
    "kind": "AgentCard",
    "card": { "name": "Hello Pod", "description": "Friendly demo agent.", "skills": [] }
  },
  "dartc": { "stream": false },
  "payload": {
    "binding": "dartc",
    "topics": ["a2a.discovery", "a2a.message", "a2a.task"]
  },
  "signature": "…"
}

What's planned

a2a.message — send / stream A2A Message objects between pods.
a2a.task — task state, subscription, cancellation, artifacts.
a2a.capability — capability / extension advertisement.

These are reserved topics today; the message / task envelopes will use the same a2a field for their typed objects.

What ships in v0.1

AgentCard shape (as we use it)

Subscribing in your host

On the wire

What's planned

See also

On this page