feat(v1): add SafeERC20 support for USDT compatibility #11

shamardy · 2026-01-30T12:42:53Z

Summary

Add SafeERC20 to EtomicSwap V1 for USDT and non-standard ERC20 support
Remove NFT functionality (ERC721/ERC1155) from V1 contract - keep ETH/ERC20 only
Fix erc20Payment() payable modifier bug (function doesn't use msg.value)
Add tokenAddress zero-check validation
Update OpenZeppelin to 5.4.0
Add Hardhat Ignition + CREATE2 deployment infra for deterministic cross-chain addresses
Deploy and verify contract on Ethereum mainnet and Sepolia

Fixes GLEECBTC/komodo-defi-framework#408

Deployed Address (all chains)

0x61EEC68Cf64d1b31e41EA713356De2563fB6D3F1

Deployed via CreateX CREATE2 factory — same address on every EVM chain.

Chain	Explorer
Ethereum	etherscan.io
Sepolia	sepolia.etherscan.io

Changes

EtomicSwap.sol

Add OpenZeppelin SafeERC20 import and using SafeERC20 for IERC20
Replace require(token.transferFrom(...)) with safeTransferFrom
Replace require(token.transfer(...)) with safeTransfer
Remove payable modifier from erc20Payment() (prevents ETH being stuck)
Add require(tokenAddress != address(0)) check
Remove all NFT-related functions (ERC721/ERC1155)
Bump Solidity to 0.8.33 (latest stable)

Deployment Infrastructure

Add Hardhat Ignition module (ignition/modules/EtomicSwapV1.js) with CREATE2 strategy
Configure 17 mainnets and 5 testnets in hardhat.config.js
Add Etherscan V2 verification (single API key for all supported chains)
Add .env.example template
Add DEPLOYMENTS.md with deployment record and runbook for remaining chains

Dependencies

Update @openzeppelin/contracts from ^5.0.0 to ^5.4.0
Update hardhat to ^2.26.0, ethers to ^6.14.0, hardhat-ethers to ^3.1.0
Add hardhat-ignition, hardhat-verify, dotenv
Move test dependencies (chai, chai-as-promised, ripemd160) to devDependencies

Tests

Remove NFT tests from V1 test suite (9 tests removed)
Update ethers version in error message check

Why SafeERC20?

USDT's transfer/transferFrom don't return a boolean. The previous code used require(token.transferFrom(...)) which fails because Solidity tries to decode a non-existent return value. SafeERC20 handles this correctly.

Testing

All 80 Hardhat tests pass
Deployed and tested on Sepolia (ETH payment/spend, payment/refund, invalid secret rejection)
Deployed and verified on Ethereum mainnet

Future TODOs (for follow-up PRs)

Deploy to remaining 16 EVM chains (see DEPLOYMENTS.md)
Fix .transfer() deprecation (uses 2300 gas limit) to support smart contract wallets (Gnosis Safe, etc.)

Add OpenZeppelin's SafeERC20 to handle non-standard ERC20 tokens like USDT that don't return a boolean from transfer/transferFrom. Changes to EtomicSwap.sol: - Add SafeERC20 import and `using SafeERC20 for IERC20` - Replace transfer/transferFrom with safeTransfer/safeTransferFrom - Remove `payable` from erc20Payment() (function doesn't use msg.value) - Add tokenAddress != address(0) validation in erc20Payment() - Bump Solidity version to 0.8.33 (latest stable) Changes to hardhat.config.js: - Update compiler to 0.8.33 - Enable optimizer with 10000 runs Co-Authored-By: Claude Opus 4.5 <[email protected]>

Remove ERC721/ERC1155/ERC165 code from V1 contract since NFT swaps use separate V2 contracts. This results in a smaller, cleaner contract focused only on ETH and ERC20 atomic swaps. Changes: - Remove NFT imports and interface implementations - Remove receiverSpendErc721, receiverSpendErc1155 functions - Remove senderRefundErc721, senderRefundErc1155 functions - Remove onERC721Received, onERC1155Received, onERC1155BatchReceived - Remove supportsInterface and isContract helper - Keep SafeERC20 for USDT compatibility - Bump package version to 1.1.0 Bytecode reduced from ~13KB to ~5KB. Co-Authored-By: Claude Opus 4.5 <[email protected]>

- Update @openzeppelin/contracts from ^5.0.0 to ^5.4.0 - Move test deps (chai, chai-as-promised, ripemd160) to devDependencies - Remove NFT tests from V1 test suite (NFT code removed from contract) - Update ethers version in test error message - Regenerate yarn.lock Co-Authored-By: Claude Opus 4.5 <[email protected]>

mariocynicys

Thanks.
Only have those comments.

Q: we will re-deploy v1 contract for ETH for the sake of getting USDT-ERC20 working, but only for ETH? no?
since other chains already have a functioning USDT-EVM20 coin?

mariocynicys · 2026-01-30T20:12:17Z

hardhat.config.js

+        enabled: true,
+        runs: 10000


Q: what is runs: 10000

The runs parameter tells the optimizer how many times each opcode will execute over the contract's lifetime - it's a trade-off between deployment cost and execution cost.

10000 is a common choice for frequently-used contracts. Higher values have diminishing returns since most inlining decisions are already made.

Ref: Solidity Optimizer Docs

P.S. I favoured execution cost (what the users pay) vs the deployment cost which is what we will pay to deploy the contract.

mariocynicys · 2026-01-30T20:19:30Z

contracts/EtomicSwap.sol

+contract EtomicSwap {
+    using SafeERC20 for IERC20;

-contract EtomicSwap is ERC165, IERC1155Receiver, IERC721Receiver {


maybe we better keep erc165?

ERC165 is for interface detection - lets other contracts query "do you support interface X?".

We had it because the old contract implemented IERC721Receiver/IERC1155Receiver for NFT support. Standard ERC20 doesn't require ERC165 (it predates it), and ERC721/ERC1155 are the ones that mandate it for their receiver callbacks.

With NFTs removed, there's no interface to advertise. Our contract uses safeTransferFrom to pull tokens (not receive via callback), so no receiver interface is needed.

shamardy · 2026-02-03T03:19:31Z

Q: we will re-deploy v1 contract for ETH for the sake of getting USDT-ERC20 working, but only for ETH? no?
since other chains already have a functioning USDT-EVM20 coin?

No need to re-deploy the others as there are no changes in KDF but tests only, so same code works for both contracts old and new. For consistency we can re-deploy others later but it's not a priority. You will see for yourself once I open the KDF PR.

- Update swap_contract_bytes and ABI for SafeERC20 V1 contract (compiled with OpenZeppelin 5.4.0) - Add USDT contract bytecode and ABI for testing - Add docker tests for USDT swaps (taker spend, maker refund) - Add docker tests for ERC20 decimal handling (6, 8, 18 decimals) - Update test helpers for USDT deployment and funding The SafeERC20 changes enable USDT and other non-standard ERC20 tokens that don't return bool from transfer/transferFrom. Related: GLEECBTC/etomic-swap#11 Co-Authored-By: Claude Opus 4.5 <[email protected]>

shamardy · 2026-02-03T04:05:54Z

KDF PR opened: GLEECBTC/komodo-defi-framework#2711

Add Hardhat Ignition module with CREATE2 strategy via CreateX factory for deterministic cross-chain deployment. Configure 17 mainnets, 5 testnets, and Etherscan V2 verification. Deploy and verify EtomicSwap V1 (SafeERC20) to Ethereum mainnet and Sepolia at 0x61EEC68Cf64d1b31e41EA713356De2563fB6D3F1. Co-Authored-By: Claude Opus 4.5 <[email protected]>

mariocynicys

LGTM!

shamardy requested a review from mariocynicys January 30, 2026 12:46

shamardy force-pushed the feat/safeerc20-v1 branch from 52cd5e5 to d2974f1 Compare January 30, 2026 15:35

mariocynicys reviewed Jan 30, 2026

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shamardy mentioned this pull request Feb 3, 2026

test(eth): add SafeERC20 V1 USDT support and docker tests GLEECBTC/komodo-defi-framework#2711

Open

shamardy mentioned this pull request Feb 4, 2026

feat: update ETH swap contract to SafeERC20 and enable USDT trading GLEECBTC/coins#1675

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mariocynicys approved these changes Feb 4, 2026

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Summary

Deployed Address (all chains)

Changes

EtomicSwap.sol

Deployment Infrastructure

Dependencies

Tests

Why SafeERC20?

Testing

Future TODOs (for follow-up PRs)

Related

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shamardy commented Jan 30, 2026 •

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