Skip to content

rsynthlabs/r402

BranchesTags

Repository files navigation

r402

verifier-as-service on x402. paid http calls return the on-chain signer of an execution proof — or anchor a signed payload to base mainnet without the producer holding any eth.

paid. signed. proven.

30-second quickstart

gate:

$ curl -i https://r402.rsynth.ai/verify/0x0b272a46e8528bff832488b88a05bd377ecaae682a62291d17cf67d8b159cae7
HTTP/2 402
payment-required: eyJ4NDAyVmVyc2lvbiI6Mi...   # base64(json)

{}

decoded payment-required:

{
  "x402Version": 2,
  "error": "Payment required",
  "resource": {
    "url": "https://r402.rsynth.ai/verify/0x0b272a46...",
    "description": "verify a $R execution proof anchored on Base",
    "mimeType": ""
  },
  "accepts": [{
    "scheme":  "exact",
    "network": "eip155:8453",
    "amount":  "1000000",
    "asset":   "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "payTo":   "0x132fA3855Dda4b2c085FCf3d79E9c3F15f78F15F",
    "maxTimeoutSeconds": 300,
    "extra":   { "name": "USD Coin", "version": "2" }
  }]
}

pay (signed EIP-3009 TransferWithAuthorization over accepts[0], base64 x402 envelope in the payment-signature header):

$ curl -H 'payment-signature: <base64 x402 envelope>' \
       https://r402.rsynth.ai/verify/0x0b272a46e8528bff832488b88a05bd377ecaae682a62291d17cf67d8b159cae7
HTTP/2 200

{
  "signer":      "0x156d727f372D06132526612b7D34CE1693365bf3",
  "payloadHash": "0x7dcea81eff042563b27f9f6e2347b09b52d976d6da95b25d1d78bc00a5cd8938",
  "signature":   "0xc25ee1f6...2903d41b",
  "timestamp":   "1779552625",
  "blockNumber": "46381639",
  "txHash":      "0x0b272a46e8528bff832488b88a05bd377ecaae682a62291d17cf67d8b159cae7"
}

examples/buyer.ts automates the envelope (see integration).

endpoints

route price what
GET /verify/:txHash $1 USDC canonical · verify an anchored execution proof
GET /api/verify/:txHash $1 USDC same handler, original path, kept live
POST /api/anchor $1 USDC anchor a signed payload to base via the relayer

read-only verify is the only route aliased to the root — /api/anchor is a write that burns relayer gas, so it keeps the /api prefix.

architecture

buyer
  |  GET /verify/<txHash>         first hit: 402 + payment-required envelope
  v                               buyer signs eip-3009, retries with payment-signature
x402 paywall                      @x402/express + openx402 facilitator, $1 USDC -> payTo
  |  paid
  v
verify handler                    tx receipt + ExecutionRecorded event + record() calldata
  |
  v
ExecutionLog on base mainnet      recover(payloadHash, signature) == indexed signer -> 200
  • seller paywall: @x402/express paymentMiddleware on /api/verify/:txHash and /api/anchor, base mainnet USDC
  • settlement: OpenX402 facilitator — permissionless, no-KYC, mainnet
  • relayer: self-hosted hot wallet via viem walletClient — pays gas only, never holds agent keys (ECDSA.recover extracts the producer's signer from the signature; tx.origin is irrelevant to attribution)
  • on-chain anchor: ExecutionLog at 0xd5A9DAF8F2134b61b73cEfaF5c9094EA162f1a1c
  • cross-language verify primitive: shared canonical encoder in python (sdk) and typescript (src/canonical.ts), byte-for-byte. sign once, verify anywhere.

response schema

every field of the 200 body:

  • signer — address recovered from the anchored signature. the producer.
  • payloadHash — keccak256 of the canonical payload bytes, as recorded on-chain
  • signature — EIP-191 signature, decoded back out of record() calldata
  • timestamp — uint256 from the ExecutionRecorded event
  • blockNumber — block of the anchor tx
  • txHash — the verified tx, echoed

there is no verified: true field — the status code is the verdict. a 200 means the address recovered from (payloadHash, signature) equals the event's indexed signer; a mismatch returns 422.

errors

status meaning
200 verified · recovered signer == on-chain signer
402 no or invalid payment · paywall runs before hash validation
400 bad_tx_hash · malformed tx hash (post-paywall)
404 tx not found or reverted
422 no ExecutionRecorded event in tx · signer mismatch
502 upstream rpc failure

verify errors are json: {"error":"<code>","detail":"<why>"}. the 402 body is {} — everything lives in the payment-required header.

organic adoption

48h since public ship, zero marketing:

metric count
anchors on base mainnet 8
external signers 3
paid usdc revenue ~$9
signups, invites, drops 0

receipts:

three strangers paid $1 USDC each within 48h of public endpoint going live. no founder ping, no airdrop, no waitlist. the endpoint speaks, somebody pays.

as of 2026-06-11: 14 anchors total · 3 non-team signers · zero marketing

integration

pnpm install
export BUYER_PRIVATE_KEY=0x...
npx tsx --env-file=.env examples/buyer.ts

the full buyer flow lives in examples/buyer.ts. x402 v2 EIP-3009 typed-data signing is hand-rolled there until x402-fetch ships a v2-compatible client; the public package still negotiates v1 against bare network names and body-encoded requirements.

full roundtrip via examples/buyer.ts (anchor + verify, ~$2 USDC):

r402 buyer roundtrip — base mainnet

  buyer:   0x156d727f372D06132526612b7D34CE1693365bf3
  payload: agent_id=1, episode_id=buyer-roundtrip-1716480000000
  hash:    0x7dcea81e...

  POST https://r402.rsynth.ai/api/anchor (paying $1.00 USDC via x402)
    → anchored: 0x0b272a46e8528bff832488b88a05bd377ecaae682a62291d17cf67d8b159cae7
    → block:    46381639
    → basescan: https://basescan.org/tx/0x0b272a46e8528bff832488b88a05bd377ecaae682a62291d17cf67d8b159cae7

  GET  https://r402.rsynth.ai/api/verify/0x0b272a46...9cae7 (paying $1.00 USDC via x402)
    → signer: 0x156d727f372D06132526612b7D34CE1693365bf3 (match: ok)
    → hash:   0x7dcea81e... (match: ok)

  roundtrip complete. total: $2.00 USDC.
  paid. signed. proven.

re-verify the genesis anchor against its pinned signer + hash ($1 USDC):

npx tsx --env-file=.env scripts/verify-genesis.ts

exit codes: 0 match · 1 bad env · 2 transport failure · 3 signer or hash mismatch.

sub-agent budgets

a main agent grants a sub-agent a $5.00 USDC spending cap via ERC-7710. the sub-agent burns through it in five $1.00 x402 calls. the sixth call's on-chain DelegationManager.redeemDelegations(...) reverts at the ERC20TransferAmountEnforcer — no balance check, no application logic, the chain refuses.

r402 sub-agent budget — base mainnet

  main:    0x<...>  (smart account, MetaMask Hybrid)
  sub:     0x<...>  (EOA, derived from main)
  cap:     5.00 USDC

  delegation granted (erc20TransferAmount, max 5.00 USDC)
    → manager:  0xdb9B1e94B5b69Df7e401DDbedE43491141047dB3
    → caveat:   ERC20TransferAmountEnforcer @ 0xf100b0819427117EcF76Ed94B358B1A5b5C6D2Fc
    → digest:   0x<...>

  → call 1/5 (paying $1.00 USDC via x402 → 0x132fA38...)
       redeem: 0x<...>
       verify: 0x156d72... (anchored signer)
  → call 2/5 ...
  → call 5/5 ...

  → call 6/5 (attempting beyond cap)
       redeem: reverted at caveat enforcer (ERC20TransferAmountEnforcer)

  budget exhausted. 5/5 used. ok.

total: ~$5.00 USDC + ~$2-3 base mainnet gas. full impl at examples/sub-agent-budget.ts. main agent is a MetaMask Hybrid smart account; sub-agent is an EOA derived deterministically from MAIN_PRIVATE_KEY so gas is funded once and the demo is replayable. @metamask/smart-accounts-kit v1.5+, DelegationManager v1.3.0 on base mainnet.

what's verified

a payload conforms to schema v0.1.0 → canonical_bytes (sorted keys, no whitespace, utf-8, .0-pinned floats) → keccak256 → EIP-191 personal_sign → ExecutionLog.record(payloadHash, signature) emits ExecutionRecorded. verification reads the event back from base mainnet, decodes the original signature from calldata, and runs recoverMessageAddress against the recorded payloadHash. recovered address must equal the indexed signer or the endpoint returns 422.

the canonical primitive is runtime-agnostic by construction: a signature produced by python (eth_account.messages.encode_defunct) recovers to the same address inside solidity (OZ MessageHashUtils.toEthSignedMessageHash + ECDSA.recover) and inside this typescript verifier (viem recoverMessageAddress). all three byte-equivalent, asserted by tests/verify.crosslang.test.ts.

run locally

pnpm install
cp .env.example .env   # fill BASE_RPC_URL, RELAYER_PRIVATE_KEY
pnpm dev

health: curl https://r402.rsynth.ai/health. env vars documented in .env.example.

cook-off

submitted to the MetaMask × 1Shot × Venice AI dev cook-off:

  • track 1 — best x402 + ERC-7710 ($3K) — primary. live base-mainnet roundtrip, USDC settlement, self-hosted permissionless relayer, sub-agent budget via ERC-7710 delegation (W4).
  • track 2 — 1Shot permissionless relayer — pivoted. 1Shot's free plan blocked smart-account creation, so the gas-relay role is filled by src/relayer.ts (self-hosted viem walletClient). same on-chain attribution semantics; ECDSA.recover recovers the producer signer regardless of tx.origin.
  • track 4 — best social media (#MetaMaskDev) — weekly build-in-public posts.

license

MIT. see LICENSE.

About

verifier-as-service on x402. verify execution proofs with ERC-7710 permission on base mainnet.

rsynth.ai/r402

Topics

typescript robotics base x402 erc-7710 erc-8004 verifiable-execution metamask-cookoff

Resources

Readme

License

MIT license
Activity

Stars

4 stars

Watchers

0 watching

Forks

1 fork
Report repository

Releases

No releases published

Packages

 
 
 

Contributors

Languages