r402

verifier-as-service for $R execution proofs. pay a few cents in USDC over x402, get back the on-chain signer of a robot execution anchored on base.

• v0.1 — W1 scaffolding shipped
• license: MIT
• verifies records emitted by ExecutionLog on base mainnet

why

buyers of robot execution data need a one-line check before paying. r402 wraps the rsynth verify flow behind an http endpoint and meters access with x402 — no custom signing, no rpc credentials, just a tx hash.

architecture

buyer agent (MM smart account + ERC-7710 delegation)
  │  GET /api/verify/:txHash
  ▼
x402 paymentMiddleware (USDC, MM facilitator)
  ▼
r402:
  → read ExecutionRecorded(signer, payloadHash) on base
  → fetch off-chain payload (agent-provided URL)
  → keccak256(canonical_bytes(payload)) == payloadHash
  → recover EIP-191 signer, == on-chain signer
  ▼
{ verified, agent_id, payload_hash, signer, block, tx_hash }

roadmap

• W1 (this commit) — scaffold, /health, canonical.ts byte-equivalent with sdk
• W2 — /api/verify/:txHash, x402 paymentMiddleware on @x402/express, MM facilitator
• W3 — buyer-side demo with @metamask/smart-accounts-kit and ERC-7710 sub-agent budget
• W4 — public deploy, demo video, submission

relation to sdk

• sdk defines the payload schema, canonical_bytes, EIP-191 signing, and the on-chain ExecutionLog contract.
• r402 ports canonical_bytes to typescript byte-for-byte (src/canonical.ts), validated against sdk/sdk/tests/test_payload.py::SCHEMA_EXAMPLE_HASH.
• the canonical schema mirrors sdk/SCHEMA.md v0.1.0 (sha1 471308f9). a drift test fails if the upstream changes.

install

pnpm install

scripts

pnpm dev        # tsx watch
pnpm build      # tsc -> dist/
pnpm start      # node dist/index.js
pnpm test       # vitest run
pnpm typecheck  # tsc --noEmit

deploy

vercel serverless. node 20 runtime. one function: api/index.ts re-exports the express app.

pnpm install
vercel --prod

env vars (set in vercel project settings):

var	required	notes
BASE_RPC_URL	yes	base MAINNET rpc (chain 8453). not sepolia.

public url: https://r402.rsynth.ai.

buyer flow

# gate
$ curl -i https://r402.rsynth.ai/api/verify/0xabc...
HTTP/2 402
content-type: application/json

{ "x402Version": 1, "accepts": [...], "error": "X-PAYMENT header is required" }

# pay
$ curl -i -H "X-PAYMENT: <signed-permit>" https://r402.rsynth.ai/api/verify/0xabc...
HTTP/2 200

{
  "verified": true,
  "agent_id": "10311",
  "payload_hash": "0xf4956c...",
  "signer": "0xe182BDa14ec3EfBAa72BC0fb6aad3145d9E64bAe",
  "anchor_tx": "0x713cf78...",
  "block": 46166628
}

@x402/client is the canonical buyer.

health

curl https://r402.rsynth.ai/health
# { "ok": true, "contract": "0xd5A9...", "chain": "base", "commit": "<sha7>" }

sanity-check after a deploy without burning usdc. commit is the 7-char VERCEL_GIT_COMMIT_SHA or "dev" locally.

license

MIT. see LICENSE.

---

robotics starts with $R.