xfuel-relay-proof-crosschain

XFuel: Relay Proof Cross-Chain

Take a settled proof and relay it to a destination domain through Hyperlane, verifying locally and dispatching the cross-chain message.

Prerequisites

• A completed task's proof (task_id) — fetch via xfuel-verify-proof.
• ZK_VERIFIER_ADDRESS and a Theta ETH-RPC URL (THETA_RPC_URL; public or a dedicated Theta node — not ZAN, which does not serve Theta RPC).
• Hyperlane must be configured server-side (setMailbox / configureDomain).

Parameters

Procedure

1. Fetch the proof and its public values:

   import { XFuelClient } from 'xfuel-sdk';
   const client = new XFuelClient({ baseUrl: process.env.XFUEL_API_URL, apiKey: process.env.XFUEL_API_KEY });
   const p = await client.getProof(task_id);
   const { proof, publicInputs: publicValues, nullifier } = p.sp1_proof;
   

2. Build the relay calldata (verified signature: relayProofCrossChain(bytes32 circuitId, bytes publicValues, bytes proofBytes, bytes32 nullifier, uint32 destDomain)):

   import { XFuelOnChain } from 'xfuel-sdk/onchain';
   const chain = new XFuelOnChain({
     rpcUrl: process.env.THETA_RPC_URL,
     zkVerifierAddress: process.env.ZK_VERIFIER_ADDRESS,
   });
   const call = chain.encodeRelayProofCrossChain(circuit_id, publicValues, proof, nullifier, dest_domain, fee_wei ?? '0');
   // -> { to, data, value }
   

3. Submit call via the server relayer or sign out-of-band. Return the resulting messageId / tx hash.

Failure modes

• NoMailbox revert → Hyperlane mailbox not configured on the verifier.
• Nullifier already spent → the proof was already relayed/settled.
• Underpaid fee_wei → dispatch reverts; quote the mailbox fee first.