cowswaprouter

TWAP order execution on CoW Protocol, in Solidity. Split a large sell order into N time-sliced parts to reduce price impact — settled through CoW's batch auction, where solvers compete and every order in a batch clears at a uniform price.

Two ways to do it, both here:

• CowTwapExecutor — a self-hosted executor. Escrow the full amount, then on a timer authorize each slice's CoW order via the PreSign scheme (setPreSignature). Solvers fill the slices; the vault relayer pulls funds during settlement.
• CowTwapHandler — the official-framework path: a ComposableCoW IConditionalOrder. Register one conditional order; CoW's watchtower calls getTradeableOrder() each block to get the part valid now, and the settlement contract calls verify() so a solver can only fill the part the handler currently authorizes — validated discretization, on-chain cancellation, no custom keeper.

How they relate, and why I rewrote the executor's CoW integration (it previously called mainnet-nonexistent deposit/settle functions): the write-up.

How CoW actually settles (the model these contracts target)

• Orders are intents, not swaps. You sign/authorize "sell ≤ X for ≥ Y by time T"; a solver settles a whole batch. There is no on-chain swap to front-run within a batch — everyone trading a pair clears at the same price (uniform clearing price = MEV protection at the batch level; each slice still sets minAmountOutPerSlice for its own limit).
• You approve the GPv2VaultRelayer (0xC92E…0110), not the settlement contract; the relayer pulls funds only as part of a settlement of an order you authorized.
• A contract authorizes an order via setPreSignature(orderUid, true) or ERC-1271 — settle() is onlySolver, so a normal contract never calls it. CowTwapExecutor presigns; it does not (and cannot) settle.

Stack

• Solidity ^0.8.20, Foundry.
• Optional: a Wake stateful fuzz suite under tests/ (kept consistent with the contracts; the Foundry suite in test/ is the executed one).

Build & test

forge build
forge test -vv     # 26 tests: executor (presign + simulated solver fill), handler, legacy

Deploy

# TWAP executor — pass the GPv2Settlement address; the vault relayer is read from it.
forge create src/CowTwapExecutor.sol:CowTwapExecutor \
  --constructor-args 0x9008D19f58AAbD9eD0D60971565AA8510560ab41   # mainnet GPv2Settlement

# ComposableCoW TWAP handler — stateless; register it as a conditional-order handler.
forge create src/CowTwapHandler.sol:CowTwapHandler

src/legacy/CowSwapRouter.sol is a deprecated single-shot deposit-and-settle sketch kept for reference (it targets a simplified interface, not the real protocol).

Security

Not audited; educational. The presign/handler logic is verified on-chain against faithful mocks (no live solver). See SECURITY.md for the threat model, the dust / in-flight-presign caveats, and the MEV protection's exact scope.