feat: open position wrapper #14

kaze-cow · 2025-11-06T00:32:51Z

Description

Implements the CowEvcOpenPositionWrapper in order to satisfy a usecase for the Euler integration.

Context

Read up on notion

Considerations

While we call this flow "open positoin wrapper", it could also be used to grow an existing position, or take on a position without buying any Euler tokens (by setting collateralAmount to 0)
this should be compatible ewith CoW (if two users open opposite positions, for example)

Out of Scope

Every line of code in this PR should be considered in-scope.

Testing Instructions

Follow the test command instructions in the README

We want to make sure:

the flow works as expected for the established cases of Euler finance.
there are not security opportunities an arbitrary user on the open internet could take advantage of
there are not security opportunities that a solver could take advantage that would give access to a significant amount of funds

fixes https://linear.app/cowswap/issue/COW-65/initial-merge-contract-of-cowevcopenpositionwrapper

* check solver on internalSettle function * check only callable through EVC * prevent reentrancy

make settlement the gatekeeper why did I not do this before

This reverts commit e56eac3.

best way to ensure the expected flow is followed exactly

* check solver on internalSettle function * check only callable through EVC * prevent reentrancy

they shouldn't have been in the repository

feat: use new wrapper from upstream

feat: working security

we use the settlement contract, so it shouldn't be needed anymore also soljson.latest is still here

Co-authored-by: Federico Giacon <[email protected]>

…otocol/euler-integration-contracts into feat/open-position-wrapper

Co-authored-by: Federico Giacon <[email protected]>

…otocol/euler-integration-contracts into feat/open-position-wrapper

should be correct now

…ed by wrappedSettle

ensures that all params are included in the signed data (this should already be the case, but now we are extra sure)

…d signatures work as expected the `_consumePreApprovedHash` method was not actually reverting--instead returning a boolean, which broke the security guarentee of consume pre approved hash. And there was no test validating the negative case for pre approved hashes

src/CowEvcBaseWrapper.sol

Co-authored-by: Federico Giacon <[email protected]>

…ly certain of the evc behavior when a signature is invalid

…otocol/euler-integration-contracts into feat/open-position-wrapper

fedgiac · 2025-12-10T16:34:59Z

src/CowEvcOpenPositionWrapper.sol

+    function getSignedCalldata(OpenPositionParams memory params) external view returns (bytes memory) {
+        (IEVC.BatchItem[] memory items,) = _encodeBatchItemsBefore(memoryLocation(params));
+        return abi.encodePacked(
+            abi.encodeCall(IEVC.batch, items), _getApprovalHash(OPEN_POSITION_PARAMS_TYPE_HASH, memoryLocation(params))
+        );
+    }
+


Since (1) this logic needs to be repeated for each wrapper and (2) the same packing is also done in the base wrapper, I'd suggest moving this to the base wrapper.
Doing something like the following would also make immediately clear the link between this function and permit:

Suggested change

function getSignedCalldata(OpenPositionParams memory params) external view returns (bytes memory) {

(IEVC.BatchItem[] memory items,) = _encodeBatchItemsBefore(memoryLocation(params));

return abi.encodePacked(

abi.encodeCall(IEVC.batch, items), _getApprovalHash(OPEN_POSITION_PARAMS_TYPE_HASH, memoryLocation(params))

);

}

function getSignedCalldata(OpenPositionParams memory params) external view returns (bytes memory) {

(IEVC.BatchItem[] memory items,) = _encodeBatchItemsBefore(memoryLocation(params));

return _encodePermitData(items, params)

);

}

under the assumption that encodePermitData is also used in _addEvcBatchItems's permit encoding.

Then in a comment of _encodePermitData we can explain why this is done (right now this comes out of nowhere).

(Yeah this doesn't work as-is because of OPEN_POSITION_PARAMS_TYPE_HASH. I'd suggest trying to make it into an immutable so that the base contract can use it, if this makes things nicer.)

fedgiac · 2025-12-10T16:40:25Z

src/CowEvcOpenPositionWrapper.sol

+        );
+    }
+
+    function getSignedCalldata(OpenPositionParams memory params) external view returns (bytes memory) {


This external function is quite important to frontends since the easiest implementation is to call it to build the permit call that needs to be executed. My suggestions are:

Adding devdocs explaining what this is for (populating permit.data)

Renaming this function to something clearer. Maybe encodePermitData or preparePermitData?

fedgiac · 2025-12-10T16:47:11Z

src/CowEvcOpenPositionWrapper.sol

+        returns (IEVC.BatchItem[] memory items, bool needsPermission)
+    {
+        OpenPositionParams memory params = paramsFromMemory(paramsLocation);
+        items = new IEVC.BatchItem[](4);


Let's make the constant relationship explicit:

Suggested change

items = new IEVC.BatchItem[](4);

items = new IEVC.BatchItem[](MAX_BATCH_OPERATIONS - 1);

Ideally there would be a test that makes sure the output of this function is indeed an array of length MAX_BATCH_OPERATIONS - 1 and not more.

fedgiac · 2025-12-10T17:43:23Z

test/CowEvcOpenPositionWrapper.t.sol

+        deal(SUSDS, user, 10000e18);
+    }
+
+    struct SettlementData {


There's a lot of code I expect will be repeating in tests for other wrappers, like SettlementData, _setupUserSusdsApproval, part of setUp, _setupUserPreApprovedFlow, _verifyPositionOpened, getOpenPositionSettlement, part of _createPermitSignature, and probably more.
I don't see this as a problem for merging this PR, but it would be a blocker for merging the next ones. 😛
Something nice for reviewability would be an intermediate PR: main -> open position -> (new) make tests more modular but add nothing new -> close position -> collateral swap. The assumption here is that the helpers won't change much in this code review, otherwise since there are so many tests to backport that it would make it significantly hard to integrate changes.

fedgiac · 2025-12-10T17:52:37Z

test/CowEvcOpenPositionWrapper.t.sol

+    function test_OpenPositionWrapper_Success() external {
+        vm.skip(bytes(forkRpcUrl).length == 0);
+
+        address account = address(uint160(user) ^ 1);


(Not a code change, just a discussion point.)
Are we guaranteed that the account the order uses is "reserved" for our trade? And if so, how? Is it the Euler frontend managing which accounts to use?

fedgiac · 2025-12-10T19:08:27Z

test/helpers/CowBaseTest.sol

+        address[] memory targets = new address[](1);
+        bytes[] memory datas = new bytes[](1);
+        targets[0] = wrapper;
+        datas[0] = abi.encodeWithSignature("wrappedSettle(bytes,bytes)", settleData, wrapperData);
+        solver.runBatch(targets, datas);


I don't understand it, why the need to run this batching setup instead of just pranking an EOA solver and directly execute wrappedSettle? Do we ever need to execute more than one operation from the solvers?

fedgiac · 2025-12-10T19:10:12Z

test/CowEvcOpenPositionWrapper.t.sol

+        assertEq(debtBefore, 0, "User should start with no debt");
+        assertEq(susdsBalanceBefore, 0, "User should start with no eSUSDS");


I believe this should be moved to where debtBefore and susdsBalanceBefore are defined, and then there should be checks on the updated balances.

fedgiac · 2025-12-10T19:13:03Z

test/CowEvcOpenPositionWrapper.t.sol

+    function _verifyPositionOpened(
+        address account,
+        uint256 expectedCollateral,
+        uint256 expectedDebt,
+        uint256 allowedDelta
+    ) internal view {
+        assertApproxEqAbs(
+            IEVault(ESUSDS).convertToAssets(IERC20(ESUSDS).balanceOf(account)),
+            expectedCollateral,
+            allowedDelta,
+            "User should have collateral deposited"
+        );
+        assertEq(IEVault(EWETH).debtOf(account), expectedDebt, "User should have debt");


This function hardcodes the vaults to ESUSDS and EWETH but many other don't. The most important thing to me is consistency, but in general I think it makes more sense to make the vault generic since it's one of the tokens and we may want to change them in other tests.

fedgiac · 2025-12-10T19:17:09Z

test/CowEvcOpenPositionWrapper.t.sol

+        executeWrappedSettlement(address(openPositionWrapper), settleData, wrapperData);
+
+        // Verify position was created successfully
+        _verifyPositionOpened(account, DEFAULT_BUY_AMOUNT + SUSDS_MARGIN, DEFAULT_BORROW_AMOUNT, 1 ether);


This function is hard to read, mostly because it has too many similar parameters. Here it makes sense to make the parameters explicit.

Suggested change

_verifyPositionOpened(account, DEFAULT_BUY_AMOUNT + SUSDS_MARGIN, DEFAULT_BORROW_AMOUNT, 1 ether);

_verifyPositionOpened({

account: account,

expectedCollateral: DEFAULT_BUY_AMOUNT + SUSDS_MARGIN,

expectedDebt: DEFAULT_BORROW_AMOUNT,

allowedDelta: 1 ether

});

fedgiac · 2025-12-10T19:22:38Z

test/CowEvcOpenPositionWrapper.t.sol

+        executeWrappedSettlement(address(openPositionWrapper), settleData, wrapperData);
+
+        // Verify position was created successfully
+        _verifyPositionOpened(account, DEFAULT_BUY_AMOUNT + SUSDS_MARGIN, DEFAULT_BORROW_AMOUNT, 1 ether);


Why do we need approximate equality in the first place? Can't we make this an exact equality?
Also, it's unclear what the delta is for, is it the collateral or the debt?
Isn't there a way for us to estimate the error exactly? What creates confusion in the amounts?

Kaze and others added 30 commits September 11, 2025 21:44

feat: pull in from PoC and minify and adjust for easy integratoin

ee6eb57

remove unnecessary console logs

0172171

fix: some security lockdowns

3e72e99

* check solver on internalSettle function * check only callable through EVC * prevent reentrancy

it builds

453c007

fix: new strategy

0f635c7

make settlement the gatekeeper why did I not do this before

compiles

5ebd847

fix tests

b168d45

forge fmt

e56eac3

enable optimizer

2e7f051

setup secrets and fix build failure

de12e99

remove sizes for now

c3dc655

Revert "forge fmt"

217af04

This reverts commit e56eac3.

use a settle state instead of original sender

4f6c81e

best way to ensure the expected flow is followed exactly

feat: pull in required vendor dependencies

2c9704a

feat: pull in from PoC and minify and adjust for easy integratoin

8982db0

remove unnecessary console logs

e9afd40

fix: some security lockdowns

35cf23b

* check solver on internalSettle function * check only callable through EVC * prevent reentrancy

remove cannon things

938b8e9

they shouldn't have been in the repository

remove unnecessary file

5ca3ae5

update all pragmas

ec9d67d

undo undos

9b7a904

fix license

164efff

Merge pull request #3 from cowprotocol/feat/new-wrapper

2d7989b

feat: use new wrapper from upstream

Merge branch 'feat/initial' into feat/security

413d162

Merge pull request #2 from cowprotocol/feat/security

3ff8dc0

feat: working security

cleanup SwapVerifier

ca207e7

we use the settlement contract, so it shouldn't be needed anymore also soljson.latest is still here

begin adding test for closing position theoretical impl

b2a9cae

add close loan test/poc concept

d65ca1a

significant improvement--no more excess on swapping out

dad08de

add wrapper

70bb676

kaze-cow and others added 21 commits December 9, 2025 16:08

Update src/PreApprovedHashes.sol

fbbbb1a

Co-authored-by: Federico Giacon <[email protected]>

Update src/CowEvcOpenPositionWrapper.sol

55982e8

Co-authored-by: Federico Giacon <[email protected]>

fix most requests from gh review

cc2b525

remove soljson

ab4c4df

Merge branch 'feat/open-position-wrapper' of https://github.com/cowpr…

591ffbd

…otocol/euler-integration-contracts into feat/open-position-wrapper

Update src/CowEvcBaseWrapper.sol

2af6f96

Co-authored-by: Federico Giacon <[email protected]>

Update src/CowEvcBaseWrapper.sol

bf0da10

Co-authored-by: Federico Giacon <[email protected]>

Update src/CowEvcBaseWrapper.sol

a734485

Co-authored-by: Federico Giacon <[email protected]>

Update src/CowEvcBaseWrapper.sol

1ab5ab5

Co-authored-by: Federico Giacon <[email protected]>

Update src/CowEvcBaseWrapper.sol

6aaa9b8

Co-authored-by: Federico Giacon <[email protected]>

Update src/CowEvcOpenPositionWrapper.sol

6ee3f0d

Co-authored-by: Federico Giacon <[email protected]>

more misc changes

0dd20ae

Merge branch 'feat/open-position-wrapper' of https://github.com/cowpr…

7797141

…otocol/euler-integration-contracts into feat/open-position-wrapper

make MAX_BATCH_OPERATIONS and PARAMS_SIZE approximately the same

b1795d6

fix build

e0d03a5

generate correct hash for EIP712 and add a test

9c9a1c5

should be correct now

add some extra tests for extra security that the EVC couldn't be call…

8afe2b6

…ed by wrappedSettle

add a comment to clarify the signature flows

4a83485

add hash of params to the end for extra safety

77d0ce6

ensures that all params are included in the signed data (this should already be the case, but now we are extra sure)

make it pure

675beab

fedgiac reviewed Dec 10, 2025

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kaze-cow and others added 7 commits December 10, 2025 20:38

Update src/CowEvcBaseWrapper.sol

246a4a0

Co-authored-by: Federico Giacon <[email protected]>

Update src/CowEvcBaseWrapper.sol

0a2ad57

Co-authored-by: Federico Giacon <[email protected]>

Update src/CowEvcBaseWrapper.sol

ce128ba

Co-authored-by: Federico Giacon <[email protected]>

add additional clarifying comment, and add an e2e test to be absolute…

6ca7a2c

…ly certain of the evc behavior when a signature is invalid

Merge branch 'feat/open-position-wrapper' of https://github.com/cowpr…

98c191a

…otocol/euler-integration-contracts into feat/open-position-wrapper

remove GPv2 reference

7efeddf

remove superfluous test and fix 712 hashing issue

53319a3

fedgiac reviewed Dec 10, 2025

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feat: open position wrapper #14

feat: open position wrapper #14

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kaze-cow commented Nov 6, 2025 •

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	items = new IEVC.BatchItem[](4);
	items = new IEVC.BatchItem[](MAX_BATCH_OPERATIONS - 1);

		assertEq(debtBefore, 0, "User should start with no debt");
		assertEq(susdsBalanceBefore, 0, "User should start with no eSUSDS");

-        _verifyPositionOpened(account, DEFAULT_BUY_AMOUNT + SUSDS_MARGIN, DEFAULT_BORROW_AMOUNT, 1 ether);
+        _verifyPositionOpened({
+            account: account,
+            expectedCollateral: DEFAULT_BUY_AMOUNT + SUSDS_MARGIN,
+            expectedDebt: DEFAULT_BORROW_AMOUNT,
+            allowedDelta: 1 ether
+        });

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kaze-cow commented Nov 6, 2025 •

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