Trusset Protocol - Infrastructure for Asset Tokenization

This page covers how to deploy, configure, and integrate with the CommodityCustody contract. It assumes you have deployed the Commodity Token suite and have a functioning identity registry and at least one CommodityTokenUpgradeable instance.

Prerequisites

Before deploying CommodityCustody, the following must be in place:

IdentityRegistryUpgradeable deployed and configured with KYC providers.
At least one CommodityTokenUpgradeable deployed via CommodityTokenFactoryUpgradeable.
USDC (or chosen settlement stablecoin) available on the target chain.
A LiquidationRouter deployed, or a placeholder address if liquidation is not yet needed.

Compiler Configuration

The batchSettleTrades function takes 9 calldata array parameters plus batchId, which exceeds the EVM’s 16-slot stack limit in the legacy compilation pipeline. The Solidity compiler must use viaIR: true.

// hardhat.config.js
module.exports = {
  solidity: {
    version: "0.8.24",
    settings: {
      optimizer: { enabled: true, runs: 200 },
      viaIR: true
    }
  }
};

Without this setting, compilation will fail with a stack-too-deep error.

Deployment Sequence

Deposit and Withdrawal

Users must deposit tokens into custody before they can place orders on the orderbook.

// Approve and deposit commodity tokens
await commodityToken.approve(custody.address, ethers.utils.parseEther("100"));
await custody.deposit(commodityToken.address, ethers.utils.parseEther("100"));

// Approve and deposit USDC
await usdc.approve(custody.address, ethers.utils.parseUnits("10000", 6));
await custody.deposit(usdc.address, ethers.utils.parseUnits("10000", 6));

There is no checkTransferability function on CommodityCustody. To pre-check whether a deposit or withdrawal will succeed, query the commodity token’s compliance state directly:

// Check whitelist status
const isWhitelisted = await commodityToken.whitelist(userAddress);

// Check if account is frozen on the token
const isFrozen = await commodityToken.frozenAccounts(userAddress);

// Check if token is paused
const isPaused = await commodityToken.paused();

// Check KYC status (if kycRequired is true on the token)
const isVerified = await identityRegistry.isVerified(userAddress);

Withdrawals work similarly. The user can only withdraw their available (unlocked) balance, and the commodity token enforces compliance during the on-chain transfer:

const available = await custody.getAvailableBalance(userAddress, commodityToken.address);
await custody.withdraw(commodityToken.address, available);

Trade Settlement Flow

The matching engine (operator) follows a lock-then-settle pattern. This is identical to the Stock Orderbook flow.

For high-throughput scenarios, use batchSettleTrades to settle multiple trades in one transaction. Size batches based on your target chain’s block gas limit. The gas guard stops processing if remaining gas drops below 80,000, so always check the BatchSettled event’s settledCount against totalSubmitted and retry any remaining settlements.

Liquidation Flows

Two paths exist for settling liquidated collateral received from a lending market.

Path A: Internal Buyer

The buyer already has USDC in custody. Tokens move between internal balances and USDC is transferred on-chain to the router.

await custody.settleLiquidationWithBuyer(
  liquidationId,
  buyerAddress,
  tokenAmount,
  usdcAmount
);

Partial fills are supported. The liquidation remains open until the full token amount is matched. Check getLiquidation(liquidationId) to see the remaining amount.

Path B: External Sale

The operator sells tokens through an external venue, then provides USDC proceeds. The commodity token enforces compliance during the on-chain transfer to the external buyer.

// Operator approves USDC to custody
await usdc.approve(custody.address, usdcReceived);

await custody.settleLiquidation(
  liquidationId,
  usdcReceived,
  externalBuyerAddress  // receives the commodity tokens
);

Both paths notify the lending market via ILendingMarket.receiveLiquidationProceeds. If the callback reverts, settlement still completes. Monitor LiquidationSettled and LiquidationSoldToBuyer events for reconciliation.

Priority Trade Flow

For liquidating tokens already held in a user’s custody balance (not received via the router):

// 1. Freeze user to prevent withdrawal front-running
await custody.freezeUser(liquidatedUser);

// 2. Lock the user's tokens
await custody.lockBalance(liquidatedUser, commodityToken.address, amount, lockId);

// 3. Settle with a buyer
await custody.settlePriorityTrade(
  settlementId,
  liquidatedUser,
  buyer,
  commodityToken.address,
  usdc.address,
  baseAmount,
  quoteAmount
);

// 4. Unfreeze the user
await custody.unfreezeUser(liquidatedUser);

On L1 Ethereum, front-running between these steps is possible. Deploy on an L2 or use a private mempool for liquidation transactions.

Listening to Events

Index these events for your backend, matching engine, and reporting systems:

// Custody operations
custody.on("Deposited", (user, token, amount, newBalance) => { /* ... */ });
custody.on("Withdrawn", (user, token, amount) => { /* ... */ });

// Trade lifecycle
custody.on("BalanceLocked", (user, token, amount, lockId) => { /* ... */ });
custody.on("TradeSettled", (settlementId, maker, taker, baseToken, quoteToken, baseAmount, quoteAmount) => { /* ... */ });
custody.on("BatchSettled", (batchId, settledCount, totalSubmitted) => { /* ... */ });

// Liquidation
custody.on("LiquidationReceived", (liquidationId, token, amount, debtOwed, borrower, lendingMarket) => { /* ... */ });
custody.on("LiquidationSettled", (liquidationId, usdcReceived, tokenRecipient) => { /* ... */ });
custody.on("LiquidationSoldToBuyer", (liquidationId, buyer, tokenAmount, usdcAmount, fullyFilled) => { /* ... */ });

// Emergency controls
custody.on("UserFrozen", (user, operator) => { /* ... */ });
custody.on("WithdrawalsPaused", (operator) => { /* ... */ });

// CRITICAL: also monitor commodity token compliance changes
commodityToken.on("TransferRestrictionModeUpdated", (oldMode, newMode) => {
  // Re-verify custody contract authorization under the new mode
});

API Integration

If you are using Trusset’s API layer, custody balances and settlements are managed through the Stock Trading API groups (which serve both stock and commodity orderbooks). The API handles deposit orchestration, settlement submission, and balance queries without direct contract interaction. For direct contract integration (self-hosted or custom deployment), use standard ethers.js or viem patterns with the contract ABIs included in the license package.

Overview

Commodity Token License

Stock Token License

Stock Orderbook License

Commodity Orderbook License

Integration

Prerequisites

Compiler Configuration

Deployment Sequence

Deposit and Withdrawal

Trade Settlement Flow

Liquidation Flows

Path A: Internal Buyer

Path B: External Sale

Priority Trade Flow

Listening to Events

API Integration

​Prerequisites

​Compiler Configuration

​Deployment Sequence

​Deposit and Withdrawal

​Trade Settlement Flow

​Liquidation Flows

​Path A: Internal Buyer

​Path B: External Sale

​Priority Trade Flow

​Listening to Events

​API Integration

Prerequisites

Compiler Configuration

Deployment Sequence

Deposit and Withdrawal

Trade Settlement Flow

Liquidation Flows

Path A: Internal Buyer

Path B: External Sale

Priority Trade Flow

Listening to Events

API Integration