Gasless Settlement

Sweepster enables users who hold only ERC-20 tokens — no native gas — to move those tokens across chains or within a chain. The user never touches native gas at any point. The whole point: a wallet holding only ERC-20s and zero native token can still sweep.

How it works

The product is EIP-7702-only. The user signs two messages off-chain — no gas, no on-chain approval, no allowance:

User signs TWO things off-chain (no gas):
  1. EIP-712 signTypedData of the SweepDelegate SweepOrder → the `bytes signature`
  2. EIP-7702 authorization delegating the EOA to the
     per-chain SweepDelegate implementation             → the `authorization`
        │
        ▼
Client submits { quoteId, signature, authorization } to POST /intents
        │
        ▼
Relayer (Kryard) broadcasts the EIP-7702 type-4 ("set-code") tx and PAYS THE GAS
        │
        ▼
The user's EOA — now temporarily running SweepDelegate code — executes
the settlement (single atomic tx, as address(this) == the user's EOA):
  1. Pull tokenIn from the EOA (self-pull; no Permit2, no approval)
  2. Swap tokenIn → canonical asset (e.g. USDC)
  3. Skim protocol fee + builder fee
  4. Hand off to delivery engine
        │
        ▼
Delivery engine:
  • Same-chain: swap/send to destination
  • Cross-chain: bridge via LI.FI / Across
        │
        ▼
Destination delivery (relayer covers destination gas)

The two off-chain signatures

Signature	What	How
Order signature	EIP-712 typed-data signature over the SweepDelegate SweepOrder. Becomes the bytes signature argument to sweep().	signTypedData({ account, ...buildDelegateTypedData(order, chainId) }) — see the Signing guide.
EIP-7702 authorization	Authorizes the user's EOA to temporarily run the per-chain SweepDelegate implementation.	walletClient.signAuthorization({ contractAddress: sweepDelegate, chainId }).

Both are produced off-chain with no gas. The authorization is required — POST /intents returns 422 if it is absent (there is no fallback path). Chains that do not support EIP-7702 are rejected at quote time.

Gas sponsorship

The Sweepster relayer (Kryard):

1. Fronts source-chain gas — broadcasts the EIP-7702 set-code transaction using its own treasury on the source chain.
2. Fronts destination-chain gas — for cross-chain sweeps, sponsors the final delivery on the destination chain.

Gas costs are recovered from the swept tokens in the same atomic settlement transaction. This is the key invariant: repayment is never separable from the transfer.

Why not Permit2?

The on-chain SweepRouter / Permit2 contracts are retained but unused by the product. Permit2 requires an on-chain approve of the Permit2 contract before the first sweep — and an approval costs gas, which defeats the zero-native-gas use case. EIP-7702 lets the EOA pull its own tokens as part of the delegated execution, so no allowance and no prior on-chain transaction are needed. The settlement contract's shared SweepSettlementBase logic (_skimFees → delivery dispatch) is the same one the SweepDelegate path runs.

Delivery modes

• Local (_deliverLocal) — same-chain swap + send to destination; enforces minAmountOut slippage.
• Cross-chain (_deliverCrossChain) — signs destChainId != block.chainid; hands the swept value to an allowlisted bridge. minAmountOut must be 0 cross-chain — slippage lives in the bridge calldata.

ERC-4337 paymaster (planned)

A verifying + ERC-20 paymaster is planned (Phase 6) as an additional gas-abstraction option alongside the current EIP-7702 path.

Related

• Source-Side Atomicity
• Token Risk Engine