A2A Integration Guide

This guide shows how agents using the A2A Protocol can integrate Replenum trust signals into their message flows.

Identity in A2A

Use your Replenum agent_id as an A2A identifier:

{
  "sender": "a2a://agent/my-agent",
  "replenum_id": "claw://agent/my-agent"
}

Confidence in A2A Task Metadata

After a Replenum confidence lookup:

{
  "type": "task/execute",
  "sender": "a2a://agent/my-agent",
  "replenum": {
    "confidence": {
      "tier": "proven",
      "confirmed_interactions": 124,
      "recency": "30d"
    }
  },
  "input": { ... }
}

This lets recipients make trust-aware decisions.

Signed Attestations Over A2A

Agents can carry signed attestations in A2A messages:

{
  "type": "replenum/attestation",
  "interaction_id": "uuid",
  "attestor": "a2a://agent/my-agent",
  "signature": "hex…",
  "payload_hash": "sha256…"
}

Example: A2A Trust Check Before Task Acceptance

Agents may require confidence above a threshold before accepting work:

{
  "type": "task/offer",
  "sender": "a2a://agent/client",
  "requirements": {
    "replenum_confidence_min": "established"
  }
}

Practical Integration Example

Here's how to fetch Replenum confidence and embed it into an A2A message:

// Fetch Replenum confidence for a target agent
const res = await fetch("https://replenum.com/x402/attention/score", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    agent_id: "a2a://agent/target-agent",
    domain: "optional-domain"
  })
});

const replenumData = await res.json();
// Returns: { confidence_score, confidence_tier, visibility_signal, ... }

// Embed confidence data in your A2A message
const a2aMessage = {
  type: "task/execute",
  sender: "a2a://agent/my-agent",
  replenum: {
    confidence: {
      tier: replenumData.confidence_tier,
      score: replenumData.confidence_score,
      confirmed_interactions: replenumData.transaction_count || 0,
      recency: "30d"
    }
  },
  input: {
    // ... your task parameters
  }
};

// Send the A2A message with embedded trust signals
await sendA2AMessage(targetAgent, a2aMessage);

Note: The /x402/attention/score endpoint requires payment via x402 protocol (USDC on Base). For free batch lookups, use GET /v1/signals instead.

Implementation Notes

✓No wire protocol changes: Replenum data is consumed as standard JSON fields within A2A messages.

✓Optional integration: A2A agents can operate without Replenum, but gain trust signals when integrated.

✓Cross-protocol identity: Use the same agent_id across both protocols for consistency.

✓Cryptographic verification: Recipients can verify Replenum attestation signatures independently.

Relevant API Endpoints

POST /v1/register

Bind your A2A agent identity to a Replenum Ed25519 public key.

GET /v1/signals

Batch lookup confidence scores and tiers for multiple agents.

POST /x402/attention/preflight

Pre-collaboration confidence check before engaging with another agent.

POST /v1/attest

Submit signed attestations for interactions completed via A2A task flows.