Published on Fri Aug 14 2026 00:00:00 GMT+0000 (Coordinated Universal Time) by Jacob Cavazos
The Difference Between Quote and Execution
You request a swap quote. You receive an expected output amount. The swap executes. You receive an actual output amount. These two numbers are not always the same. The difference is called surplus. What happens to that surplus determines your real cost.
Surplus arises for several reasons. The routing engine may find a better path than the initial quote suggested. A pool that was not queried at quote time may have better reserves by execution time. A multi-hop route through an intermediate token may produce a better effective price than the direct route. Price impact may be lower than estimated if the swap is split across multiple pools. An RFQ market maker may offer a firm quote that beats the AMM price. The market may move in your favor between quote and execution.
On Base, block times are 2 seconds. The window between quote and execution is small. But it is not zero. Within that window, conditions change. Surplus is the positive difference. Slippage is the negative difference. Both are real. Both affect what you actually receive.
Who Keeps the Surplus
This is where aggregators differ. This is not always transparent.
Some aggregators keep the surplus. The user receives the quoted amount. Or the minimum received after slippage tolerance. The aggregator retains any excess as additional revenue. This is common with aggregators that charge 0% or low advertised fees. The surplus is how they actually make money. The headline fee looks low. The effective cost is higher. The aggregator is capturing value the user could have received.
Some aggregators return the surplus to the user. The user receives the actual executed output. The executed output may be higher than the quoted amount. The aggregator’s revenue is limited to the stated platform fee. This is less common. It requires the aggregator to forgo a revenue source. It is more transparent. The fee you see is the fee you pay.
The difficulty for users is that surplus retention is invisible. The swap interface shows quoted: 3.33 WETH, received: 3.33 WETH. But if the execution actually produced 3.35 WETH and the aggregator kept 0.02 WETH, the user has no way to know. The received amount matches the quote. Everything looks correct. The surplus extraction is hidden in the gap between execution and display. The construct hides the cost. The territory shows the cost.
How to Tell the Difference
The only reliable way to know whether an aggregator returns surplus is to compare the actual executed output against the received amount. The actual executed output is visible on the block explorer. The received amount is visible in your wallet. If the block explorer shows the swap produced 3.35 WETH but you received 3.33 WETH, the aggregator kept 0.02 WETH. If the block explorer shows 3.35 WETH and you received 3.35 WETH, the aggregator returned the surplus.
This requires checking every swap on a block explorer. Most users do not do this. For institutional users doing large swaps, the difference is material. A 0.2% surplus on a $100,000 swap is $200. Whether the aggregator keeps it or returns it is a $200 question that most users never know they are asking.
The TVMExecutor Design
TVMExecutor is the contract we deployed on Base mainnet. It is designed to be transparent about this. The contract takes a fixed 9 bps fee from the output. The contract forwards the remainder to the user. The fee is deducted on-chain. The fee is visible in the transaction events. The fee is verifiable on Basescan.
Whatever the execution produces, the user receives the output minus 9 bps. There is no hidden surplus retention. The contract’s fee logic is in the verified source code. Anyone can trace the exact flow of tokens through the transaction. Anyone can verify that the user received the executed output minus 9 bps. Anyone can verify that the aggregator did not keep the surplus.
This does not mean every swap produces surplus. Most swaps execute close to the quoted price. Slippage is more common than positive surplus during volatile periods. But when surplus does occur, it goes to the user. Not to the aggregator. The 9 bps fee is the total platform cost. There is no second layer of value extraction hidden in the execution. There is no dynamic fee. There is no surplus retention. There is one fee. It is fixed. It is on-chain. It is verifiable.
Why This Matters for Cost Comparison
When comparing aggregator costs, the advertised fee is only part of the picture. The total cost is: pool fees plus platform fee plus gas plus MEV exposure minus surplus returned. An aggregator that charges 0% platform fee but keeps surplus may have a higher effective cost than an aggregator that charges 9 bps but returns surplus. The only way to know is to measure the actual received amounts. Not the quoted amounts. The actual received amounts.
We have written before about how performance is the new trust layer in DeFi infrastructure. Surplus handling is part of that. A system that claims 0% fees but silently retains surplus is not actually cheaper. It is less transparent about what it costs. A system that charges a fixed, verifiable fee and returns surplus to the user is more expensive on paper. It is potentially cheaper in practice.
The construct says free. The territory says 9 bps. The construct hides the surplus. The territory returns the surplus. The construct says trust the interface. The territory says check the block explorer. The construct says the fee is zero. The territory says the fee is what you actually paid, not what the interface displayed.
The contract is public. The fee is fixed. The source code is verified. That is the level of transparency that lets users verify their actual costs. Not the quoted costs. The actual costs. The costs that leave your wallet. The costs that the construct hides. The costs that the territory shows.
Related: TVMExecutor: Nine Basis Points, No Exceptions · Performance Is The New Trust Layer · Why Base’s Liquidity Graph Leaks Value
Written by Jacob Cavazos
← Back to blog
