Gas Sponsorship

Farmers and field agents cannot be expected to hold MNT for gas. AsiliChain sponsors gas for all farmer-initiated and agent-initiated transactions. Cooperative-initiated transactions are funded by cooperative wallets.

Who Pays Gas for What

Actor	Transaction type	Gas paid by	Annual cost estimate
Farmer (USSD)	BatchToken mint via DELIVERED	AsiliChain API wallet	~$0.10/batch
Field agent (agent app)	FarmerRegistry.registerFarmer	AsiliChain API wallet	~$0.05/farmer
Cooperative quality officer	TraceLog.updateStage (GRADED)	Cooperative wallet	~$0.001/batch
Cooperative manager	PurchaseOrder confirmation	Cooperative wallet	~$0.002/PO
Exporter	TraceLog.updateStage (EXPORTED)	Exporter wallet	~$0.001/export
LendingVault auto-exec	SETTLED stage, CreditScore update	LendingVault (self-funded from fees)	Covered by protocol fee

Total annual gas cost for a 500-batch cooperative: ~$7 (Mantle ZK rollup at $0.002 per proof).

Implementation: API Wallet as Gas Relayer

For farmer and agent transactions, the AsiliChain API wallet acts as a relayer — it submits the transaction and pays the gas on behalf of the farmer.

packages/api/lib/gasRelay.ts

import { walletClient, publicClient } from './mantle';
import { parseAbi } from 'viem';

export async function relayMintBatch(params: MintBatchParams) {
  // API wallet signs and pays gas — farmer has no wallet, no MNT
  const hash = await walletClient.writeContract({
    address: BATCH_TOKEN_ADDRESS,
    abi: batchTokenAbi,
    functionName: 'mintBatch',
    args: [
      params.cooperativeWallet,
      params.farmerId,
      params.weightKg,
      params.grade,
      params.moisturePct,
      params.collectionPointHash,
      params.weightSlipIpfsCid,
    ],
    account: API_RELAYER_WALLET, // AsiliChain API wallet pays gas
  });

  const receipt = await publicClient.waitForTransactionReceipt({ hash });
  return receipt;
}

API Wallet Funding

The AsiliChain API relayer wallet needs MNT for gas. At $0.002 per transaction and a Phase 1 volume of 500 batches per season:

Phase 1:  500 batches × $0.002 = $1.00/season in gas
Phase 2:  5,000 batches × $0.002 = $10.00/season in gas
Phase 3:  25,000 batches × $0.002 = $50.00/season in gas

Fund the API wallet with $50 MNT at deployment — sufficient for multiple seasons of Phase 1 volume. Set an alert at $5 remaining balance.

Mantle Native Gas Sponsorship (EIP-4337)

Mantle supports EIP-4337 (Account Abstraction). For Phase 2+, AsiliChain can implement a paymaster contract that:

• Accepts farmer USSD sessions as gas-free
• Reimburses the paymaster from the 4% protocol fee pool
• Removes the relayer wallet architecture entirely

This is a Phase 2 improvement — not required for Phase 1 pilot. Document as a planned upgrade in the protocol roadmap.

Gas Monitoring

// Alert if API wallet balance drops below threshold
export async function checkGasBalance() {
  const balance = await publicClient.getBalance({
    address: API_RELAYER_WALLET,
  });

  const balanceMNT = Number(balance) / 1e18;

  if (balanceMNT < 5) {
    // Send alert to cooperative dashboard + Slack/email
    await sendAlert({
      severity: 'warning',
      message: `API relayer wallet low: ${balanceMNT.toFixed(4)} MNT. Top up required.`,
    });
  }
}