Fetching Purchase Fees | Agora Finance

The AgoraStableSwapPair contract stores the current purchase-fee rate (in 18-dec “fee precision” units) for each token direction:

token0PurchaseFee – fee charged when buying token0 (i.e., swapping into token0).
token1PurchaseFee – fee charged when buying token1.

1. Pick a pair address

1 // AUSD / CTK pair on Avalanche Fuji Testnet
2 const TESTNET_PAIR_AUSD_CTK = '0x237591AaF2FCCb34464Ceae9EeA1eb6f375843AF';

2. Helper to read the purchase fees

1 /**
2  * Returns raw purchase-fee rates (18-dec precision).
3  */
4 async function getPairPurchaseFees(
5   pair: `0x${string}`,
6 ): Promise<{ token0PurchaseFee: bigint; token1PurchaseFee: bigint }> {
7   const token0PurchaseFee = await client.readContract({
8     address: pair,
9     abi: stableSwapAbi,
10     functionName: "token0PurchaseFee",
11     args: [],
12   });
13 
14   const token1PurchaseFee = await client.readContract({
15     address: pair,
16     abi: stableSwapAbi,
17     functionName: "token1PurchaseFee",
18     args: [],
19   });
20 
21   return { token0PurchaseFee, token1PurchaseFee };
22 }

3. Run the query

1 (async () => {
2   const { token0PurchaseFee, token1PurchaseFee } = await getPairPurchaseFees(
3     TESTNET_PAIR_AUSD_CTK,
4   );
5 
6   console.log("Purchase fee (token0 → token1):", token0PurchaseFee);
7   console.log("Purchase fee (token1 → token0):", token1PurchaseFee);
8 })();

1 Purchase fee (token0 → token1): 100000000000000n   // 0.01% (1 bps)
2 Purchase fee (token1 → token0): 200000000000000n   // 0.02% (2 bps)

This is the value stored by the contract. In order to convert these units to human readable values, we’ll need to divide the output by the ERC20 token decimals.