wip: buy with stable/cusd #291

sirpy · 2025-12-22T15:14:50Z

Description

about: #290

sourcery-ai

Hey - I've found 3 issues, and left some high level feedback:

In BuyGDCloneV2.swap, the Bought event emitted in the cUSD/stable branch still uses celo as the token address, which will mislead consumers of the event and should be updated to emit the correct token (likely CUSD or stable).
In swapCusd, gasCosts are carved out from the contract’s CUSD balance but the refund is paid in stable, which will fail or behave unexpectedly when stable != CUSD; consider refunding from the same token the gas was reserved in or explicitly ensuring sufficient stable balance for the refund.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- In `BuyGDCloneV2.swap`, the `Bought` event emitted in the cUSD/stable branch still uses `celo` as the token address, which will mislead consumers of the event and should be updated to emit the correct token (likely `CUSD` or `stable`).
- In `swapCusd`, `gasCosts` are carved out from the contract’s `CUSD` balance but the refund is paid in `stable`, which will fail or behave unexpectedly when `stable != CUSD`; consider refunding from the same token the gas was reserved in or explicitly ensuring sufficient `stable` balance for the refund.

## Individual Comments

### Comment 1
<location> `contracts/utils/BuyGDClone.sol:93-101` </location>
<code_context>
 		uint256 gasCosts;
+		uint24[] memory fees = new uint24[](1);
+		fees[0] = 100;
 		if (refundGas != owner) {
-			(gasCosts, ) = oracle.quoteAllAvailablePoolsWithTimePeriod(
+			(gasCosts, ) = oracle.quoteSpecificFeeTiersWithTimePeriod(
</code_context>

<issue_to_address>
**issue (bug_risk):** Gas refund is taken from CUSD balance but paid out in `stable`, which can mis-account funds when `stable != CUSD`.

`swapCusd` subtracts `gasCosts` from the CUSD balance (`amountIn = ERC20(CUSD).balanceOf(address(this)) - gasCosts;`) but sends the refund in `stable` (`ERC20(stable).transfer(refundGas, gasCosts)`). When `stable != CUSD`, this reduces CUSD while spending an unreserved amount of `stable`, which can desync balances and underfund future swaps. Consider either refunding in CUSD or charging gas costs from `stable` consistently.
</issue_to_address>

### Comment 2
<location> `contracts/utils/BuyGDClone.sol:72` </location>
<code_context>
 			return bought;
 		}
-		balance = ERC20(cusd).balanceOf(address(this));
+		balance = ERC20(CUSD).balanceOf(address(this));
 		if (balance > 0) {
 			bought = swapCusd(_minAmount, refundGas);
</code_context>

<issue_to_address>
**issue (bug_risk):** `swap` only checks CUSD balance, even though the contract now supports a generic `stable` token.

The second branch still checks `ERC20(CUSD).balanceOf(address(this))` and calls `swapCusd`, so if `stable` is set to a different token and only that token is funded, this path never runs and those funds are never swapped. Either restrict the docstring to CUSD only, or update this branch to work off `stable` (and a corresponding `swapStable`) when `stable != CUSD`.
</issue_to_address>

### Comment 3
<location> `contracts/utils/BuyGDClone.sol:34` </location>
<code_context>

 	constructor(
 		ISwapRouter _router,
-		address _cusd,
+		address _stable,
 		address _gd,
</code_context>

<issue_to_address>
**nitpick:** Constructor parameter name `_cusd` in `DonateGDClone` is now misleading since it represents a generic stable token.

The parameter is still named `_cusd` in `DonateGDClone` while it now represents a generic stable token and is passed through to `BuyGDCloneV2`. Please rename it to `_stable` to align with `BuyGDCloneV2` and avoid confusion when deploying with non-cUSD stablecoins.
</issue_to_address>

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contracts/utils/BuyGDClone.sol

openzeppelin-code · 2025-12-22T15:34:54Z

wip: buy with stable/cusd

Generated at commit: 6d50918c7561bb8029b7c81ae5690418e8f0f52e

🚨 Report Summary

	Severity Level	Results
Contracts	Critical High Medium Low Note Total	3 5 0 16 44 68
Dependencies	Critical High Medium Low Note Total	0 0 1 0 130 131

For more details view the full report in OpenZeppelin Code Inspector

…s for Celo fork

…d error handling

… in BuyGDClone tests

…etwork mismatch in BuyGDClone tests

blueogin · 2026-01-05T19:06:30Z

@sirpy
I’ve completed step 1 for BuyGDClone - the swap from cUSD to G$ works successfully via the cUSD -> GLO -> G$ path on Uniswap.

contracts/utils/BuyGDClone.sol

sirpy · 2026-01-06T11:14:34Z

test/utils/BuyGDClone.test.ts

+    console.log("✓ Factory stable token verified:", factoryStable);
+
+    // Impersonate a whale account to get cUSD
+    await ethers.provider.send("hardhat_impersonateAccount", [CUSD_WHALE]);


use ethers.getImpersonatedAccount

still not done

sirpy · 2026-01-06T11:17:10Z

test/utils/BuyGDClone.test.ts

+    console.log("✓ Received amount >= minAmount");
+  });
+
+  it("Should verify swap path: cUSD -> stable -> G$", async function () {


there's no swap test here

I think it's not required

then it shuold be called "verify swap" if it doesnt swap

test/utils/BuyGDClone.test.ts

sirpy · 2026-01-06T11:21:10Z

test/utils/BuyGDClone.test.ts

+    console.log("✓ Clone created successfully at:", cloneAddress);
+  });
+
+  it("Should swap cUSD -> GLOUSD -> G$ via clone", async function () {


add test for celo -> glousd -> G$

add a test to compare quote from oracle (mintwap) vs actual pool price

you dont need minamount = 95% in tests, since mintwap is 98%

add a test with minamount > 98%

Hardhat forking tests cannot verify this behavior because the CELO native token relies on the precompiled TRANSFER contract on Celo, and Hardhat’s forked EVM does not support or execute that precompile.

added

fixed it to use mintwap as minAmount

added

…ap methods and error handling

…ds and tests for expected return and error handling

…ional scenarios for expected returns and error handling

…ew methods for expected returns and enhanced error handling in tests

sirpy · 2026-01-07T15:33:09Z

test/utils/BuyGDClone.test.ts

+    console.log("✓ Factory stable token verified:", factoryStable);
+
+    // Impersonate a whale account to get cUSD
+    await ethers.provider.send("hardhat_impersonateAccount", [CUSD_WHALE]);


still not done

sirpy · 2026-01-07T15:35:12Z

test/utils/BuyGDClone.test.ts

+
+    // Min TWAP should be less than or equal to actual (98% buffer)
+    // But allow some tolerance for price movement
+    expect(minTwap).to.be.lte(actualPrice.mul(105).div(100)); // Allow 5% tolerance


you need to check both gt/lt to verify it is in an acceptable range, what if it is close to 0?

sirpy · 2026-01-07T15:35:55Z

test/utils/BuyGDClone.test.ts

+    const whaleBalance = await cusdToken.balanceOf(whale.address);
+
+    if (whaleBalance.lt(swapAmount)) {
+      console.log("⚠ Whale doesn't have enough cUSD, skipping test");


it should throw an error meaning we cant use the whale account

wip: buy with stable/cusd

d201e14

sourcery-ai bot reviewed Dec 22, 2025

View reviewed changes

contracts/utils/BuyGDClone.sol Show resolved Hide resolved

blueogin added 4 commits January 5, 2026 11:36

feat: enhance BuyGDClone with createAndSwap function and add E2E test…

bba0f75

…s for Celo fork

refactor: improve Celo forking logic in BuyGDClone tests with enhance…

ca35ebb

…d error handling

refactor: skip test on Celo fork failure instead of throwing an error…

fca8771

… in BuyGDClone tests

refactor: simplify Celo forking logic by directly skipping tests on n…

24ab3c7

…etwork mismatch in BuyGDClone tests

sirpy commented Jan 6, 2026

View reviewed changes

sirpy assigned blueogin Jan 6, 2026

blueogin added 5 commits January 6, 2026 08:03

feat: integrate Mento reserve functionality in BuyGDClone with new sw…

6fcefa9

…ap methods and error handling

feat: add Mento reserve integration in BuyGDClone with new swap metho…

a7170db

…ds and tests for expected return and error handling

feat: extend Mento reserve integration in BuyGDClone tests with addit…

b36221f

…ional scenarios for expected returns and error handling

feat: implement Mento reserve swap functionality in BuyGDClone with n…

9bad74d

…ew methods for expected returns and enhanced error handling in tests

refactor: use ethers.getImpersonatedSigner function

6d50918

sirpy commented Jan 7, 2026

View reviewed changes

wip: buy with stable/cusd #291

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wip: buy with stable/cusd #291

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sirpy commented Dec 22, 2025

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openzeppelin-code bot commented Dec 22, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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wip: buy with stable/cusd

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blueogin commented Jan 5, 2026

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openzeppelin-code bot commented Dec 22, 2025 •

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