POC Borrow and lend callbacks by peyha · Pull Request #552 · morpho-org/midnight

peyha · 2026-03-23T14:06:10Z

The borrow callback supply collaterals on behalf of the user (maker or taker) while the lend callback withdraws the liquidity (either from another obligation or from a morpho vault) on behalf of the user.

Additional questions

Should the lend callback be separated into 2 contracts ? One for morpho vault and one for midnight

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chatgpt-codex-connector · 2026-03-23T14:14:22Z

+            IERC4626(vault).withdraw(buyerAssets, buyer, buyer);
+        } else if (withdrawType == WithdrawType.Midnight) {
+            address obligationDataAddress = address(uint160(uint256(withdrawData)));
+            Obligation memory otherObligation = abi.decode(obligationDataAddress.code, (Obligation));
+            Midnight(midnight).withdraw(otherObligation, buyerAssets, buyer, buyer);


Reject callback sources that use a different loan token

onBuy never checks that the selected source actually matches obligation.loanToken. If callbackData points to a vault or another Midnight obligation for a different asset and the buyer already has the traded loan token approved to Midnight, the callback will withdraw the wrong asset first and Midnight.take will still settle using the buyer's wallet balance. That turns a bad source configuration into an unintended extra withdrawal instead of a clean revert.

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not sure it should be required, could be a comment

chatgpt-codex-connector · 2026-03-23T14:14:22Z

+    function withdraw(uint256 assets, address receiver, address) external returns (uint256) {
+        ERC20(asset).transfer(receiver, assets);
+        return assets;


Make the vault mock enforce ERC4626 ownership rules

MockVault.withdraw ignores the owner argument and has no share or allowance accounting, so the new testOnBuyVaultV2* cases can pass even when LenderCallback.onBuy would revert against a compliant ERC4626. In particular, the callback currently calls withdraw(buyerAssets, buyer, buyer) as a third party, and this mock never exercises the approval check that a real vault would perform.

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will update the test with arbitrary vault v2 when the adapter is live

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chatgpt-codex-connector · 2026-04-01T12:57:24Z

+    {
+        require(msg.sender == MIDNIGHT, "unauthorized");
+        address vault = abi.decode(data, (address));
+        IERC4626(vault).withdraw(buyerAssets, buyer, buyer);


Validate vault asset before withdrawing

onBuy withdraws from any vault address in data but never checks that IERC4626(vault).asset() matches the offer’s obligation.loanToken. When the source vault holds a different asset and the buyer already has/approved the obligation loan token, take still succeeds by pulling the loan token from the wallet while also draining the unrelated vault asset, turning a bad callback config into unintended extra withdrawal. Fresh evidence after the callback split: this new VaultLenderCallback path ignores the Obligation token fields entirely.

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same as before, it could be a comment

chatgpt-codex-connector · 2026-04-01T12:57:24Z

+        require(msg.sender == MIDNIGHT, "unauthorized");
+        bytes32 otherObligationId = abi.decode(data, (bytes32));
+        Obligation memory otherObligation = abi.decode(address(uint160(uint256(otherObligationId))).code, (Obligation));
+        Midnight(MIDNIGHT).withdraw(otherObligation, buyerAssets, buyer, buyer);


Validate source obligation token before withdrawing

onBuy decodes an arbitrary source obligation from data and immediately calls Midnight.withdraw without verifying that otherObligation.loanToken equals the traded obligation.loanToken. If data points to a different-token obligation and the buyer has approved the traded token, settlement can still complete from wallet balance while withdrawing unrelated funds from the source obligation, so a misconfigured callback does not fail closed. Fresh evidence after the split: the new ObligationLenderCallback still ignores the destination obligation’s token in this path.

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same as before, it could be a comment

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Co-authored-by: prd-carapulse[bot] <264278285+prd-carapulse[bot]@users.noreply.github.com> Co-authored-by: Quentin Garchery <garchery.quentin@gmail.com>

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chatgpt-codex-connector · 2026-04-28T09:24:16Z

+        require(msg.sender == MIDNIGHT, "unauthorized");
+        CollateralData[] memory collateralData = abi.decode(data, (CollateralData[]));
+        for (uint256 i = 0; i < collateralData.length; i++) {
+            Midnight(MIDNIGHT)


Add allowance setup for collateral transfers

BorrowerCallback.onSell calls Midnight.supplyCollateral from the callback address, but this contract never grants MIDNIGHT an allowance for collateral tokens and exposes no function to do so. On-chain, a regular ERC20 collateral therefore reverts on first use when supplyCollateral reaches safeTransferFrom with allowance(callback, MIDNIGHT) == 0. The new tests pass only because they impersonate the callback address with vm.prank(...) to call approve, which is not possible in production.

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chatgpt-codex-connector · 2026-05-19T07:51:15Z

+        require(msg.sender == MIDNIGHT, "unauthorized");
+        bytes32 otherMarketId = abi.decode(data, (bytes32));
+        Market memory otherMarket = abi.decode(address(uint160(uint256(otherMarketId))).code, (Market));
+        Midnight(MIDNIGHT).withdraw(otherMarket, buyerAssets, buyer, address(this));


Reject withdrawing from the market being filled

When data points to the same market as the active take, this withdraw can burn the buyer's just-booked credit before the callback payment is collected, because Midnight.take updates credit/debt and then invokes the buy callback before the loan-token transfers. If the market already has withdrawable liquidity, a lender can fund a new borrow from existing repaid funds without bringing external assets, leaving the new debt unmatched by lender credit. Keep the id callback parameter and reject a source market whose decoded/recomputed id equals it, e.g. require(Midnight(MIDNIGHT).toId(otherMarket) != id, "same market");.

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feat: first version

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peyha added 5 commits March 23, 2026 15:16

lint

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test

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refactor: separate lend callback

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Merge branch 'main' into feat/callbacks

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chore: lint

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peyha added 4 commits April 7, 2026 16:14

Merge branch 'main' into feat/callbacks

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feat: update callback

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test

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chore: lint

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Comment thread test/LenderCallbackTest.sol Outdated

MathisGD and others added 17 commits April 21, 2026 18:27

check size in ci (#680)

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test: fix testReturnJumps (#683)

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Allow ApprovalRatifier approvals to be delegated (#686)

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[Certora] onlyAuthorizedCanChange liquidate (#492)

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Missing tests for full coverage (#687)

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naming: is ratified (#695)

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cvl context (#698)

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update position returns more values (#690)

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use IMidnight interface (#691)

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Small tweaks (#703)

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[Certora] Refactor division by zero (#702)

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test with an old version of foundry (#696)

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minor naming changes (#697)

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Rename fee -> trading fee (#705)

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separate callbacks (#704)

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no solc metadata (#706)

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MathisGD and others added 4 commits April 21, 2026 18:28

refactor take bundler (#710)

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arbitrary callback targets (#688)

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test: cover missing require sites for ObligationNotCreated (#708)

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Merge branch 'main' into feat/callbacks

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MathisGD changed the title ~~Borrow and lend callbacks~~ POC Borrow and lend callbacks May 13, 2026

peyha self-assigned this May 13, 2026

peyha added 2 commits May 18, 2026 18:53

test: fix for weird erc20

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Merge branch 'main' into feat/callbacks

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Comment thread src/periphery/BorrowerCallback.sol Outdated

peyha added 2 commits May 19, 2026 09:46

refactor: obligation -> market

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chore: fmt

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refactor: custom error

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test: custom error

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peyha commented Mar 23, 2026 •

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